Principal Financial (PFG) 10-K 8 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2016	Feb. 01, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	PRINCIPAL FINANCIAL GROUP INC
Entity Central Index Key	1,126,328
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 11.8
Entity Common Stock, Shares Outstanding		287,476,821
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Assets
Fixed maturities, available-for-sale (2016 and 2015 include $232.5 million and $257.4 million related to consolidated variable interest entities)	$ 54,846.1	$ 49,966.5
Fixed maturities, trading (2016 and 2015 include $82.4 million and $100.4 million related to consolidated variable interest entities)	398.4	686.8
Equity securities, available-for-sale	98.9	104.5
Equity securities, trading (2016 and 2015 include $721.9 million and $640.9 million related to consolidated variable interest entities)	1,413.4	1,202.7
Mortgage loans	13,230.2	12,339.4
Real estate (2016 and 2015 include $305.7 million and $354.5 million related to consolidated variable interest entities)	1,368.8	1,451.8
Policy loans	823.8	817.1
Other investments (2016 and 2015 include $89.8 million and $29.5 million related to consolidated variable interest entities and $86.2 million and $53.4 million measured at fair value under the fair value option)	3,655.9	3,251.7
Total investments	75,835.5	69,820.5
Cash and cash equivalents	2,719.6	2,564.8
Accrued investment income	580.6	545.6
Premiums due and other receivables	1,361.9	1,429.3
Deferred acquisition costs	3,380.2	3,276.1
Property and equipment	699	633.8
Goodwill	1,020.8	1,009
Other intangibles	1,325.3	1,359.2
Separate account assets (2016 and 2015 include $35,884.1 million and $33,300.4 million related to consolidated variable interest entities)	139,832.6	136,978.9
Other assets	1,258.8	1,043.1
Total assets	228,014.3	218,660.3
Liabilities
Contractholder funds (2016 and 2015 include $358.7 million and $338.9 million related to consolidated variable interest entities)	37,953.6	35,716.1
Future policy benefits and claims	29,000.7	25,856.5
Other policyholder funds	890.4	805.4
Short-term debt	51.4	181.1
Long-term debt (2016 and 2015 include $0.0 million and $42.8 million related to consolidated variable interest entities)	3,125.7	3,265.2
Income taxes currently payable	12.9	18.4
Deferred income taxes	972.4	697.2
Separate account liabilities (2016 and 2015 include $35,844.1 million and $33,300.4 million related to consolidated variable interest entities)	139,832.6	136,978.9
Other liabilities (2016 and 2015 include $284.1 million and $345.9 million related to consolidated variable interest entities, of which $59.9 million and $68.1 million are measured at fair value under the fair value option)	5,783.3	5,678.4
Total liabilities	217,623	209,197.2
Redeemable noncontrolling interest (2016 includes $58.8 million related to consolidated variable interest entities)	97.5	85.7
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 469.2 million and 466.2 million shares issued, and 287.7 million and 291.4 million shares outstanding in 2016 and 2015	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost (181.5 million and 174.8 million shares in 2016 and 2015)	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Noncontrolling interest	66.5	65.8
Total stockholders' equity	10,293.8	9,377.4
Total liabilities and stockholders' equity	$ 228,014.3	$ 218,660.3

Consolidated Statements of Fin3

Consolidated Statements of Financial Position (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fixed maturities, available-for-sale	$ 54,846.1	$ 49,966.5
Fixed maturities, trading	398.4	686.8
Equity securities, trading	1,413.4	1,202.7
Real estate	1,368.8	1,451.8
Other investments	3,655.9	3,251.7
Other investments measured at fair value under fair value option	86.2	53.4
Separate account assets	139,832.6	136,978.9
Contractholder funds	37,953.6	35,716.1
Long-term debt	3,125.7	3,265.2
Separate account liabilities	139,832.6	136,978.9
Other liabilities	5,783.3	5,678.4
Redeemable noncontrolling interest	$ 97.5	$ 85.7
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	2,500	2,500
Common stock, issued (in shares)	469.2	466.2
Common stock, outstanding (in shares)	287.7	291.4
Treasury stock (in shares)	181.5	174.8
Aggregate consolidated variable interest entities
Fixed maturities, available-for-sale	$ 232.5	$ 257.4
Fixed maturities, trading	82.4	100.4
Equity securities, trading	721.9	640.9
Real estate	305.7	354.5
Other investments	89.8	29.5
Separate account assets	35,844.1	33,300.4
Contractholder funds	358.7	338.9
Long-term debt	0	42.8
Separate account liabilities	35,844.1	33,300.4
Other liabilities	284.1	345.9
Other liabilities measured at fair value under fair value option	59.9	$ 68.1
Redeemable noncontrolling interest	$ 58.8

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Premiums and other considerations	$ 5,299.1	$ 5,310.3	$ 3,722.9
Fees and other revenues	3,627.4	3,653.1	3,482.1
Net investment income (loss)	3,296.5	3,052.1	3,257.9
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities	269.5	(20.9)	92.7
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	(98.8)	(0.8)	23.8
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income	0.4	(29.4)	(101.8)
Net impairment (losses) recoveries on available-for-sale securities	(98.4)	(30.2)	(78)
Net realized capital gains (losses)	171.1	(51.1)	14.7
Total revenues	12,394.1	11,964.4	10,477.6
Expenses
Benefits, claims and settlement expenses	6,913.2	6,697.7	5,231
Dividends to policyholders	156.6	163.5	177.4
Operating expenses	3,732.6	3,672.4	3,574.3
Total expenses	10,802.4	10,533.6	8,982.7
Income (loss) before income taxes	1,591.7	1,430.8	1,494.9
Income taxes (benefits)	229.9	177.6	318.5
Net income (loss)	1,361.8	1,253.2	1,176.4
Net income (loss) attributable to noncontrolling interest	45.3	19.2	32.3
Net income (loss) attributable to Principal Financial Group, Inc.	1,316.5	1,234	1,144.1
Preferred stock dividends		16.5	33
Excess of redemption value over carrying value of preferred shares redeemed		8.2
Net income (loss) available to common stockholders	$ 1,316.5	$ 1,209.3	$ 1,111.1
Earnings per common share
Basic earnings per common share (in dollars per share)	$ 4.55	$ 4.11	$ 3.70
Diluted earnings per common share (in dollars per share)	4.50	4.06	3.65
Dividends declared per common share (in dollars per share)	$ 1.61	$ 1.50	$ 1.28

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Comprehensive Income
Net income (loss)	$ 1,361.8	$ 1,253.2	$ 1,176.4
Other comprehensive income (loss), net:
Net unrealized gains (losses) on available-for-sale securities	99.1	(470.7)	324.7
Noncredit component of impairment losses on fixed maturities, available-for-sale	(3.5)	19.1	61.9
Net unrealized gains (losses) on derivative instruments	15.5	19.2	61.1
Foreign currency translation adjustment	68.1	(471.6)	(336.6)
Net unrecognized postretirement benefit obligation	41.8	(39.1)	(255.2)
Other comprehensive income (loss)	221	(943.1)	(144.1)
Comprehensive income (loss)	1,582.8	310.1	1,032.3
Comprehensive income (loss) attributable to noncontrolling interest	49.7	(1.3)	21
Comprehensive income (loss) attributable to Principal Financial Group, Inc.	$ 1,533.1	$ 311.4	$ 1,011.3

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions		Series APreferred stock	Series BPreferred stock	Common stock	Additional paid-in capital	Retained earnings (accumulated deficit)	Accumulated other comprehensive income (loss)	Treasury stock	Noncontrolling interest	Total
Balances at Dec. 31, 2013		$ 0	$ 0.1	$ 4.6	$ 9,798.9	$ 5,405.4	$ 183.2	$ (5,708)	$ 92.8	$ 9,777
Increase (decrease) in stockholders' equity
Common stock issued					77.5					77.5
Stock-based compensation and additional related tax benefits					80.3	(6.1)				74.2
Treasury stock acquired, common								(222.7)		(222.7)
Dividends to common stockholders						(376.6)				(376.6)
Dividends to preferred stockholders						(33)				(33)
Distributions to noncontrolling interest									(23.9)	(23.9)
Contributions from noncontrolling interest									7.4	7.4
Purchase of subsidiary shares from noncontrolling interest	[1]				(2)				(45.6)	(47.6)
Adjustments to redemption amount of redeemable noncontrolling interest					(9.2)	(19.7)				(28.9)
Net income (loss)	[1]					1,144.1			23.3	1,167.4
Other comprehensive income (loss)	[1]						(132.8)		(6)	(138.8)
Balances at Dec. 31, 2014		0	0.1	4.6	9,945.5	6,114.1	50.4	(5,930.7)	48	10,232
Increase (decrease) in stockholders' equity
Common stock issued				0.1	76					76.1
Stock-based compensation and additional related tax benefits					90.6	(6.5)			0.1	84.2
Treasury stock acquired, common								(300.6)		(300.6)
Dividends to common stockholders						(441)				(441)
Dividends to preferred stockholders						(16.5)				(16.5)
Preferred stock redemption			(0.1)		(541.7)	(8.2)				(550)
Distributions to noncontrolling interest									(15.4)	(15.4)
Contributions from noncontrolling interest									7.7	7.7
Purchase of subsidiary shares from noncontrolling interest	[1]				(19)		(10.3)		12.8	(16.5)
Adjustments to redemption amount of redeemable noncontrolling interest					(6.6)					(6.6)
Net income (loss)	[1]					1,234			14.3	1,248.3
Other comprehensive income (loss)	[1]						(922.6)		(1.7)	(924.3)
Balances at Dec. 31, 2015		0	0	4.7	9,544.8	6,875.9	(882.5)	(6,231.3)	65.8	9,377.4
Increase (decrease) in stockholders' equity
Common stock issued					37.8					37.8
Stock-based compensation and additional related tax benefits					92.5	(7.1)			0.4	85.8
Treasury stock acquired, common								(277.3)		(277.3)
Dividends to common stockholders						(464.9)				(464.9)
Distributions to noncontrolling interest									(34.8)	(34.8)
Contributions from noncontrolling interest									5.5	5.5
Purchase of subsidiary shares from noncontrolling interest	[1]				15.1		(9.3)			5.8
Adjustments to redemption amount of redeemable noncontrolling interest					(4.2)					(4.2)
Net income (loss)	[1]					1,316.5			28.5	1,345
Other comprehensive income (loss)	[1]						216.6		1.1	217.7
Balances at Dec. 31, 2016		$ 0	$ 0	$ 4.7	$ 9,686	$ 7,720.4	$ (675.2)	$ (6,508.6)	$ 66.5	$ 10,293.8
[1]	Excludes amounts attributable to redeemable noncontrolling interest. See Note 13, Stockholders’ Equity, for further details.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income (loss)	$ 1,361.8	$ 1,253.2	$ 1,176.4
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of deferred acquisition costs	285.1	270.8	367.2
Additions to deferred acquisition costs	(402.3)	(390.3)	(404.1)
Accrued investment income	(35)	(39.7)	26.2
Net cash flows for trading securities	166.5	(201.9)	(93.4)
Premiums due and other receivables	98.7	(211.5)	26.9
Contractholder and policyholder liabilities and dividends	2,140.3	3,283.6	1,634
Current and deferred income taxes (benefits)	45.8	(66.5)	175.9
Net realized capital (gains) losses	(171.1)	51.1	(14.7)
Depreciation and amortization expense	186.6	193	169.5
Mortgage loans held for sale, sold or repaid, net of gain			43.3
Real estate acquired through operating activities	(58.2)	(44.1)	(49.4)
Real estate sold through operating activities	229	53.7	158.9
Stock-based compensation	84.4	84.5	75.3
Other	(73.8)	141.2	(189.1)
Net adjustments	2,496	3,123.9	1,926.5
Net cash provided by (used in) operating activities	3,857.8	4,377.1	3,102.9
Investing activities
Available-for-sale securities: Purchases	(13,763.8)	(9,920.3)	(9,054)
Available-for-sale securities: Sales	1,890.5	1,563	2,512
Available-for-sale securities: Maturities	7,742.8	6,625.9	6,244.7
Mortgage loans acquired or originated	(2,889)	(2,275.1)	(2,169.6)
Mortgage loans sold or repaid	2,068.7	1,687.3	1,793.6
Real estate acquired	(109.7)	(322)	(281.7)
Net (purchases) sales of property and equipment	(154.9)	(136.4)	(136)
Purchase of interests in subsidiaries, net of cash acquired		(291.2)
Net change in other investments	61.5	(98.8)	(81.7)
Net cash provided by (used in) investing activities	(5,153.9)	(3,167.6)	(1,172.7)
Financing activities
Issuance of common stock	37.8	76.1	77.5
Acquisition of treasury stock	(277.3)	(300.6)	(222.7)
Proceeds from financing element derivatives	0.4	0.3	15.1
Payments for financing element derivatives	(87.7)	(82)	(58)
Excess tax benefits from share-based payment arrangements	12	15.7	9.7
Purchase of subsidiary shares from noncontrolling interest	(2.4)	(22.5)	(227)
Dividends to common stockholders	(464.9)	(441)	(376.6)
Dividends to preferred stockholders		(16.5)	(33)
Preferred stock redemption		(550)
Issuance of long-term debt	656.1	804.9	38.5
Principal repayments of long-term debt	(799.3)	(52.6)	(100.3)
Net proceeds from (repayments of) short-term borrowings	(131.4)	157	(118.3)
Investment contract deposits	10,770.9	6,492.3	5,638.4
Investment contract withdrawals	(8,392.7)	(6,666.8)	(7,099.2)
Net increase (decrease) in banking operation deposits	129	91.1	30.7
Other	0.4	(14)	(12.9)
Net cash provided by (used in) financing activities	1,450.9	(508.6)	(2,438.1)
Net increase (decrease) in cash and cash equivalents	154.8	700.9	(507.9)
Cash and cash equivalents at beginning of period	2,564.8	1,863.9	2,371.8
Cash and cash equivalents at end of period	2,719.6	2,564.8	1,863.9
Supplemental information:
Cash paid for interest	162	149.6	137.6
Cash paid for income taxes	178.8	$ 129.6	$ 73.8
Supplemental disclosure of non-cash activities:
Assets received in kind for pension risk transfer transactions	$ 594.3

Nature of Operations and Signif

Nature of Operations and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Nature of Operations and Significant Accounting Policies
Nature of Operations and Significant Accounting Policies	1. Nature of Operations and Significant Accounting Policies Description of Business Principal Financial Group, Inc. ("PFG") is a leader in global investment management offering businesses, individuals and institutional clients a wide range of financial products and services, including retirement, asset management and insurance through our diverse family of financial services companies. Basis of Presentation The accompanying consolidated financial statements include the accounts of PFG and all other entities in which we directly or indirectly have a controlling financial interest as well as those variable interest entities ("VIEs") in which we are the primary beneficiary. The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("U.S. GAAP"). All significant intercompany accounts and transactions have been eliminated. Consolidation We have relationships with various special purpose entities and other legal entities that must be evaluated to determine if the entities meet the criteria of a VIE or a voting interest entity ("VOE"). This assessment is performed by reviewing contractual, ownership and other rights, including involvement of related parties, and requires use of judgment. First, we determine if we hold a variable interest in an entity by assessing if we have the right to receive expected losses and expected residual returns of the entity. If we hold a variable interest, then the entity is assessed to determine if it is a VIE. An entity is a VIE if the equity at risk is not sufficient to support its activities, if the equity holders lack a controlling financial interest or if the entity is structured with non-substantive voting rights. In addition to the previous criteria, if the entity is a limited partnership or similar entity, it is a VIE if the limited partners do not have the power to direct the entity's most significant activities through substantive kick-out rights or participating rights. A VIE is evaluated to determine the primary beneficiary. The primary beneficiary of a VIE is the enterprise with (1) the power to direct the activities of a VIE that most significantly impact the entity's economic performance and (2) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE. When we are the primary beneficiary, we are required to consolidate the entity in our financial statements. We reassess our involvement with VIEs on a quarterly basis. For further information about VIEs, refer to Note 3, Variable Interest Entities. If an entity is not a VIE, it is considered a VOE. VOEs are generally consolidated if we own a greater than 50% voting interest. If we determine our involvement in an entity no longer meets the requirements for consolidation under either the VIE or VOE models, the entity is deconsolidated. Entities in which we have significant management influence over the operating and financing decisions but are not required to consolidate, other than investments accounted for at fair value under the fair value option, are reported using the equity method. Recent Accounting Pronouncements ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Description Date of Effect on our consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Standards not yet adopted: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Goodwill impairment testing This authoritative guidance is to simplify how an entity is required to test goodwill for impairment by eliminating Step 2 (which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill) from the goodwill impairment test. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. Early adoption is permitted. January 1, 2020 We are currently evaluating the impact this guidance will have on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Description Date of Effect on our consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Credit losses This authoritative guidance requires entities to use a current expected credit loss ("CECL") model to measure impairment for most financial assets that are not recorded at fair value through net income. Under the CECL model, an entity will estimate lifetime expected credit losses considering available relevant information about historical events, current conditions and reasonable and supportable forecasts. The CECL model does not apply to available-for-sale debt securities. This guidance also expands the required credit loss disclosures and will be applied using a modified retrospective approach by recording a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. Early adoption is permitted. January 1, 2020 We are currently evaluating the impact this guidance will have on our consolidated financial statements. We believe estimated credit losses under the CECL model will generally result in earlier loss recognition for loans and other receivables. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Leases This authoritative guidance requires lessee recognition of lease assets and lease liabilities on the balance sheet. The concept of an operating lease, where the lease assets and liabilities are off balance sheet, is eliminated under the new guidance. For lessors, the guidance modifies lease classification criteria and accounting for certain types of leases. Other key aspects of the guidance relate to the removal of the current real estate-specific guidance and new presentation and disclosure requirements. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach, which includes certain optional practical expedients that may be elected. Early adoption is permitted. January 1, 2019 This guidance will require us to add our operating leases to the balance sheet. We are currently evaluating other impacts this guidance will have on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Definition of a business This authoritative guidance clarifies the definition of a business to assist with evaluating when transactions involving an integrated set of assets and activities (a "set") should be accounted for as acquisitions or disposals of assets or businesses. The guidance requires that when substantially all of the fair value of the gross assets acquired or disposed of is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The guidance also requires a set to include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output to be considered a business. Lastly, the guidance removes the evaluation of whether a market participant could replace missing elements and narrows the definition of outputs by more closely aligning it with how outputs are described in the revenue recognition guidance. The guidance will be applied prospectively. Early application is permitted in certain circumstances. January 1, 2018 We are currently evaluating the impact this guidance will have on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Description Date of Effect on our consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Financial instruments — recognition and measurement This authoritative guidance addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. The primary focus of this guidance is to supersede the guidance to classify equity securities with readily determinable fair values into different categories (trading or available-for-sale) and requires equity securities to be measured at fair value with changes in the fair value recognized through net income. This guidance requires adoption through a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. January 1, 2018 We are currently evaluating the impact this guidance will have on our consolidated financial statements. As of December 31, 2016, we do not hold material equity securities accounted for at fair value through other comprehensive income that will be accounted for at fair value through net income under the updated guidance. This change is not expected to have a material impact on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue recognition This authoritative guidance replaces all general and most industry specific revenue recognition guidance (excluding insurance) currently prescribed by U.S. GAAP. The core principle is that an entity recognizes revenue to reflect the transfer of a promised good or service to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for that good or service. This guidance also provides clarification on when an entity is a principal or an agent in a transaction. The guidance may be applied using one of the following two methods: (1) retrospectively to each prior reporting period presented, or (2) retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application. January 1, 2018 We are currently evaluating the impact this guidance will have on our consolidated financial statements. Only a portion of our revenues are impacted by this guidance because the guidance does not apply to revenue on contracts accounted for under the financial instruments or insurance contracts standards. Our evaluation process includes, but is not limited to, identifying contracts within the scope of the guidance, reviewing and documenting our accounting for these contracts, and identifying and determining the accounting for any related contract costs. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income tax — intra-entity transfers of assets This authoritative guidance requires entities to recognize current and deferred income tax resulting from an intra-entity asset transfer when the transfer occurs. Prior to issuance of this guidance, U.S. GAAP did not allow recognition of income tax consequences until the asset had been sold to a third party. This guidance requires adoption through a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption with early adoption permitted. January 1, 2018 We are currently evaluating the impact this guidance will have on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee share-based payment accounting This authoritative guidance changes certain aspects of accounting for and reporting share-based payments to employees including changes related to the income tax effects of share-based payments, tax withholding requirements and accounting for forfeitures. Various transition methods will apply depending on the situation being addressed. January 1, 2017 The guidance will be adopted prospectively as indicated by the guidance for each area of change and will not have a material impact on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Description Date of Effect on our consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Standards adopted: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short-duration insurance contracts This authoritative guidance requires additional disclosures related to short-duration insurance contracts. December 31, 2016 The disclosure requirements of this guidance were adopted retrospectively. See Note 8, Insurance Liabilities, for further details. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net asset value per share as a practical expedient for fair value This authoritative guidance removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. January 1, 2016 The guidance was adopted retrospectively and did not have a material impact on our consolidated financial statements. See Note 14, Fair Value Measurements, for further details. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Simplifying the presentation of debt issuance costs This authoritative guidance requires debt issuance costs related to a recognized debt liability to be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. January 1, 2016 The guidance was adopted retrospectively and did not have a material impact on our consolidated financial statements. See Note 9, Debt, for further details. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consolidations This authoritative guidance makes changes to both the variable interest and voting interest consolidation models and eliminates the investment company deferral for portions of the variable interest model. The amendments in the standard impact the consolidation analysis for interests in investment companies and limited partnerships and similar entities. January 1, 2016 The guidance was adopted using the modified retrospective approach. See Note 3, Variable Interest Entities, for further details. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Discontinued operations This authoritative guidance amends the definition of discontinued operations and requires entities to provide additional disclosures associated with discontinued operations, as well as disposal transactions that do not meet the discontinued operations criteria. The guidance requires discontinued operations treatment for disposals of a component or group of components of an entity that represents a strategic shift that has or will have a major impact on an entity's operations or financial results. The guidance also expands the scope to disposals of equity method investments and businesses that, upon initial acquisition, qualify as held for sale. January 1, 2015 This guidance was adopted prospectively and did not have a material impact on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of financial assets and liabilities of a consolidated collateralized financing entity This authoritative guidance provides a measurement alternative for a reporting entity to measure both the financial assets and financial liabilities of consolidated collateralized financing entities ("CCFEs") using the more observable of the fair value of the financial assets or of the financial liabilities for both the financial assets and financial liabilities. January 1, 2015 This guidance was adopted using a modified retrospective approach and did not have a material impact on our consolidated financial statements. See Note 14, Fair Value Measurements, for further details. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Description Date of Effect on our consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency cumulative translation adjustment This authoritative guidance clarifies how the cumulative translation adjustment related to a parent's investment in a foreign entity should be released when certain transactions related to the foreign entity occur. January 1, 2014 The guidance was adopted prospectively and did not have a material impact on our consolidated financial statements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ When we adopt new accounting standards, we have a process in place to perform a thorough review of the pronouncement, identify the financial statement and system impacts and create an implementation plan among our impacted business units to ensure we are compliant with the pronouncement on the date of adoption. This includes having effective processes and controls in place to support the reported amounts. Each of the standards listed above is in varying stages in our implementation process based on its issuance and adoption dates. We are on track to implement guidance by the respective effective dates. Use of Estimates in the Preparation of Financial Statements The preparation of our consolidated financial statements and accompanying notes requires management to make estimates and assumptions that affect the amounts reported and disclosed. These estimates and assumptions could change in the future as more information becomes known, which could impact the amounts reported and disclosed in the consolidated financial statements and accompanying notes. The most critical estimates include those used in determining: • the fair value of investments in the absence of quoted market values; • investment impairments and valuation allowances; • the fair value of and accounting for derivatives; • the deferred acquisition costs ("DAC") and other actuarial balances where the amortization is based on estimated gross profits; • the measurement of goodwill, indefinite lived intangible assets, finite lived intangible assets and related impairments or amortization, if any; • the liability for future policy benefits and claims; • the value of our pension and other postretirement benefit obligations and • accounting for income taxes and the valuation of deferred tax assets. A description of such critical estimates is incorporated within the discussion of the related accounting policies that follow. In applying these policies, management makes subjective and complex judgments that frequently require estimates about matters that are inherently uncertain. Many of these policies, estimates and related judgments are common in the insurance and financial services industries; others are specific to our businesses and operations. Actual results could differ from these estimates. Closed Block Principal Life Insurance Company ("Principal Life") operates a closed block ("Closed Block") for the benefit of individual participating dividend-paying policies in force at the time of the 1998 mutual insurance holding company ("MIHC") formation. See Note 6, Closed Block, for further details. Cash and Cash Equivalents Cash and cash equivalents include cash on hand, money market instruments and other debt issues with a maturity date of three months or less when purchased. Investments Fixed maturities include bonds, asset-backed securities ("ABS"), redeemable preferred stock and certain non-redeemable preferred securities. Equity securities include mutual funds, common stock, non-redeemable preferred stock and required regulatory investments. We classify fixed maturities and equity securities as either available-for-sale or trading at the time of the purchase and, accordingly, carry them at fair value. See Note 14, Fair Value Measurements, for methodologies related to the determination of fair value. Unrealized gains and losses related to available-for-sale securities, excluding those in fair value hedging relationships, are reflected in stockholders' equity, net of adjustments associated with DAC and related actuarial balances, derivatives in cash flow hedge relationships and applicable income taxes. Unrealized gains and losses related to hedged portions of available-for-sale securities in fair value hedging relationships and mark-to-market adjustments on certain trading securities are reflected in net realized capital gains (losses). Mark-to-market adjustments related to certain securities carried at fair value with an investment objective to realize economic value through mark-to-market changes are reflected in net investment income. The cost of fixed maturities is adjusted for amortization of premiums and accrual of discounts, both computed using the interest method. The cost of fixed maturities and equity securities classified as available-for-sale is adjusted for declines in value that are other than temporary. Impairments in value deemed to be other than temporary are primarily reported in net income as a component of net realized capital gains (losses), with noncredit impairment losses for certain fixed maturities, available-for-sale reported in other comprehensive income ("OCI"). Interest income, as well as prepayment fees and the amortization of the related premium or discount, is reported in net investment income. For loan-backed and structured securities, we recognize income using a constant effective yield based on currently anticipated cash flows. Real estate investments are reported at cost less accumulated depreciation. The initial cost bases of properties acquired through loan foreclosures are the lower of the fair market values of the properties at the time of foreclosure or the outstanding loan balance. Buildings and land improvements are generally depreciated on the straight-line method over the estimated useful life of improvements and tenant improvement costs are depreciated on the straight-line method over the term of the related lease. We recognize impairment losses for properties when indicators of impairment are present and a property's expected undiscounted cash flows are not sufficient to recover the property's carrying value. In such cases, the cost basis of the properties are reduced to fair value. Real estate expected to be disposed is carried at the lower of cost or fair value, less cost to sell, with valuation allowances established accordingly and depreciation no longer recognized. The carrying amount of real estate held for sale was $130.7 million and $169.7 million as of December 31, 2016 and 2015, respectively. Any impairment losses and any changes in valuation allowances are reported in net income. Commercial and residential mortgage loans are generally reported at cost adjusted for amortization of premiums and accrual of discounts, computed using the interest method and net of valuation allowances. Interest income is accrued on the principal amount of the loan based on the loan's contractual interest rate. Interest income, as well as prepayment of fees and the amortization of the related premium or discount, is reported in net investment income. Any changes in the valuation allowances are reported in net income as net realized capital gains (losses). We measure impairment based upon the difference between carrying value and estimated value less cost to sell. Estimated value is based on either the present value of expected cash flows discounted at the loan's effective interest rate, the loan's observable market price or the fair value of the collateral. If foreclosure is probable, the measurement of any valuation allowance is based upon the fair value of the collateral. Net realized capital gains and losses on sales of investments are determined on the basis of specific identification. In general, in addition to realized capital gains and losses on investment sales and periodic settlements on derivatives not designated as hedges, we report gains and losses related to the following in net realized capital gains (losses): other-than-temporary impairments of securities and subsequent realized recoveries, mark-to-market adjustments on certain trading securities, mark-to-market adjustments on sponsored investment funds, fair value hedge and cash flow hedge ineffectiveness, mark-to-market adjustments on derivatives not designated as hedges, changes in the mortgage loan valuation allowance provision, impairments of real estate held for investment and impairments of equity method investments. Investment gains and losses on sales of certain real estate held for sale due to investment strategy and mark-to-market adjustments on certain securities carried at fair value with an investment objective to realize economic value through mark-to-market changes are reported as net investment income and are excluded from net realized capital gains (losses). Policy loans and certain other investments are reported at cost. Interests in unconsolidated entities, joint ventures and partnerships are generally accounted for using the equity method. We have other investments reported at fair value or for which the fair value option has been elected. See Note 14, Fair Value Measurements, for detail on these investments. Derivatives Overview Derivatives are financial instruments whose values are derived from interest rates, foreign exchange rates, financial indices or the values of securities. Derivatives generally used by us include interest rate swaps, interest rate options, swaptions, currency swaps, currency forwards, equity options, futures, credit default swaps and total return swaps. Derivative positions are either assets or liabilities in the consolidated statements of financial position and are measured at fair value, generally by obtaining quoted market prices or through the use of pricing models. See Note 14, Fair Value Measurements, for policies related to the determination of fair value. Fair values can be affected by changes in interest rates, foreign exchange rates, financial indices, values of securities, credit spreads, and market volatility and liquidity. Accounting and Financial Statement Presentation We designate derivatives as either: (a) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, including those denominated in a foreign currency ("fair value hedge"); (b) a hedge of a forecasted transaction or the exposure to variability of cash flows to be received or paid related to a recognized asset or liability, including those denominated in a foreign currency ("cash flow hedge"); (c) a hedge of a net investment in a foreign operation or (d) a derivative not designated as a hedging instrument. Our accounting for the ongoing changes in fair value of a derivative depends on the intended use of the derivative and the designation, as described above, and is determined when the derivative contract is entered into or at the time of redesignation. Hedge accounting is used for derivatives that are specifically designated in advance as hedges and that reduce our exposure to an indicated risk by having a high correlation between changes in the value of the derivatives and the items being hedged at both the inception of the hedge and throughout the hedge period. Fair Value Hedges. When a derivative is designated as a fair value hedge and is determined to be highly effective, changes in its fair value, along with changes in the fair value of the hedged asset, liability or firm commitment attributable to the hedged risk, are reported in net realized capital gains (losses). Any difference between the net change in fair value of the derivative and the hedged item represents hedge ineffectiveness. Cash Flow Hedges. When a derivative is designated as a cash flow hedge and is determined to be highly effective, changes in its fair value are recorded as a component of OCI. Any hedge ineffectiveness is recorded immediately in net income. At the time the variability of cash flows being hedged impacts net income, the related portion of deferred gains or losses on the derivative instrument is reclassified and reported in net income. Net Investment in a Foreign Operation Hedge. When a derivative is used as a hedge of a net investment in a foreign operation, its change in fair value, to the extent effective as a hedge, is recorded as a component of OCI. Any hedge ineffectiveness is recorded immediately in net income. If the foreign operation is sold or upon complete or substantially complete liquidation, the deferred gains or losses on the derivative instrument are reclassified into net income. Non-Hedge Derivatives. If a derivative does not qualify or is not designated for hedge accounting, all changes in fair value are reported in net income without considering the changes in the fair value of the economically associated assets or liabilities. Hedge Documentation and Effectiveness Testing. At inception, we formally document all relationships between hedging instruments and hedged items, as well as our risk management objective and strategy for undertaking various hedge transactions. This process includes associating all derivatives designated as fair value or cash flow hedges with specific assets or liabilities on the consolidated statements of financial position or with specific firm commitments or forecasted transactions. Effectiveness of the hedge is formally assessed at inception and throughout the life of the hedging relationship. Even if a derivative is highly effective and qualifies for hedge accounting treatment, the hedge might have some ineffectiveness. We use qualitative and quantitative methods to assess hedge effectiveness. Qualitative methods may include monitoring changes to terms and conditions and counterparty credit ratings. Quantitative methods may include statistical tests including regression analysis and minimum variance and dollar offset techniques. Termination of Hedge Accounting. We prospectively discontinue hedge accounting when (1) the criteria to qualify for hedge accounting is no longer met, e.g., a derivative is determined to no longer be highly effective in offsetting the change in fair value or cash flows of a hedged item; (2) the derivative expires, is sold, terminated or exercised or (3) we remove the designation of the derivative being the hedging instrument for a fair value or cash flow hedge. If it is determined that a derivative no longer qualifies as an effective hedge, the derivative will continue to be carried on the consolidated statements of financial position at its fair value, with changes in fair value recognized prospectively in net realized capital gains (losses). The asset or liability under a fair value hedge will no longer be adjusted for changes in fair value pursuant to hedging rules and the existing basis adjustment is amortized to the consolidated statements of operations line associated with the asset or liability. The component of accumulated other comprehensive income ("AOCI") related to discontinued cash flow hedges that are no longer highly effective is amortized to the consolidated statements of operations consistent with the net income impacts of the original hedged cash flows. If a cash flow hedge is discontinued because it is probable the hedged forecasted transaction will not occur, the deferred gain or loss is immediately reclassified from AOCI into net income. Embedded Derivatives. We purchase and issue certain financial instruments and products that contain a derivative that is embedded in the financial instrument or product. We assess whether this embedded derivative is clearly and closely related to the asset or liability that serves as its host contract. If we deem that the embedded derivative's terms are not clearly and closely related to the host contract, and a separate instrument with the same terms would qualify as a derivative instrument, the derivative is bifurcated from that contract and held at fair value on the consolidated statements of financial position, with changes in fair value reported in net income. Contractholder and Policyholder Liabilities Contractholder and policyholder liabilities (contractholder funds, future policy benefits and claims and other policyholder funds) include reserves for investment contracts, individual and group annuities that provide periodic income payments, universal life, term life insurance, participating traditional individual life insurance, group life insurance, health insurance and disability income policies, as well as a provision for dividends on participating policies. Investment contracts are contractholders' funds on deposit with us and generally include reserves for pension and annuity contracts. Reserves on investment contracts are equal to the cumulative deposits less any applicable charges and withdrawals plus credited interest. Reserves for universal life insurance contracts are equal to cumulative deposits less charges plus credited interest, which represents the account balances that accrue to the benefit of the policyholders. We hold additional reserves on certain long-duration contracts where benefit features result in gains in early years followed by losses in later years, universal life/variable universal life contracts that contain no lapse guarantee features, or annuities with guaranteed minimum death benefits. Reserves for individual and group annuities that provide periodic income payments, nonparticipating term life insurance and disability income contracts are computed on a basis of assumed investment yield, mortality, morbidity and expenses, including a provision for adverse deviation, which generally varies by plan, year of issue and policy duration. Investment yield is based on our experience. Mortality, morbidity and withdrawal rate assumptions are based on our experience and are periodically reviewed against both industry st

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill and Other Intangible Assets
Goodwill and Other Intangible Assets	2. Goodwill and Other Intangible Assets Goodwill The changes in the carrying amount of goodwill reported in our segments were as follows: Retirement Principal Principal U.S. Corporate Consolidated (in millions) Balance as of January 1, 2015 $ $ $ $ $ — $ Goodwill from acquisitions — — — Foreign currency — ) ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of December 31, 2015 — Foreign currency — ) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of December 31, 2016 $ $ $ $ $ — $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ On September 1, 2015, we completed our purchase of AXA's Mandatory Provident Fund ("MPF") and Occupational Retirement Schemes Ordinance ("ORSO") pension business in Hong Kong for $335.5 million. As part of the transaction, we entered into an exclusive 15-year distribution agreement with AXA to provide co-branded pension products through AXA's extensive agency network in Hong Kong. AXA's MPF and ORSO pension business is consolidated within our Principal International segment with a portion of the goodwill and identifiable intangible assets allocated to our Principal Global Investors segment. Of the acquired intangible assets, $104.8 million was assigned to goodwill and is not subject to amortization. The goodwill is largely related to future sales anticipated from our internal workforce and entity-specific revenue synergies that will be generated by combining AXA's MPF and ORSO pension business with our existing businesses. This goodwill will be tested annually as part of the Principal International Hong Kong reporting unit and the Principal Global Investors Equity Investments and Fixed Income Investments reporting units. Of the remaining acquired intangible assets, $138.0 million was assigned to customer relationships, which are subject to amortization over a 30-year useful life, and $53.0 million was assigned to the distribution agreement, which is subject to amortization over a 15-year useful life based on its contractual term. Finite Lived Intangible Assets Amortized intangible assets that continue to be subject to amortization over a weighted average remaining expected life of 16 years were as follows: December 31, 2016 2015 (in millions) Gross carrying value $ $ Accumulated amortization ​ ​ ​ ​ ​ ​ ​ ​ Net carrying value $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ During 2015, we recorded an $8.3 million pre-tax impairment loss in operating expenses related to finite lived intangible assets that originated from the acquisition of our mutual fund company in Brazil with a gross carrying amount of $11.5 million and $3.2 million of accumulated amortization at the time of impairment. During 2016, 2015 and 2014, we fully amortized other finite lived intangible assets of $2.2 million, $0.5 million and $118.6 million, respectively. The amortization expense for intangible assets with finite useful lives was $44.5 million, $42.5 million and $49.9 million for 2016, 2015 and 2014, respectively. As of December 31, 2016, the estimated amortization expense for the next five years is as follows (in millions): Year ending December 31: 2017 $ 2018 2019 2020 2021 Indefinite Lived Intangible Assets The 2015 net impact of impairments of indefinite lived intangibles of our mutual fund company in Brazil resulted in a pre-tax loss of $14.7 million that was recorded in operating expenses. The net carrying amount of unamortized indefinite lived intangible assets was $797.8 million and $790.6 million as of December 31, 2016 and 2015, respectively. As of both December 31, 2016 and 2015, $608.0 million relates to investment management contracts associated with our acquisition of WM Advisors, Inc. in 2006. The remaining balance primarily relates to the trade name intangible associated with our acquisition of Administradora de Fondos de Pensiones Cuprum S.A. in 2013.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2016
Variable Interest Entities
Variable Interest Entities	3. Variable Interest Entities We have relationships with various types of entities which may be VIEs. Certain VIEs are consolidated in our financial results. See Note 1, Nature of Operations and Significant Accounting Policies, under the caption "Consolidation" for further details of our consolidation accounting policies. We did not provide financial or other support to investees designated as VIEs for the periods ended December 31, 2016 and December 31, 2015. Adoption of New Consolidation Guidance Both the variable interest and voting interest consolidation models were changed under authoritative guidance effective January 1, 2016. The guidance eliminated the investment company deferral for portions of the variable interest model. Prior to January 1, 2016, the primary beneficiary of an investment company VIE was the enterprise who absorbed the majority of the entity's expected losses, received a majority of the expected residual returns or both. The new guidance requires all VIEs to be assessed under one method to determine the primary beneficiary. The determination of whether interests in limited partnerships and similar entities are VIEs or VOEs has also changed under the pronouncement, by requiring evaluation of the equity holders' rights to determine if they have the power to direct the entity's most significant activities through substantive kick-out rights or participating rights. Limited partnerships and similar entities without these rights are VIEs. We adopted the guidance using the modified retrospective approach effective January 1, 2016. Under the modified retrospective approach, the cumulative effect of initially applying the new guidance is recognized as of the date of initial application, and comparative periods are not restated. The changes resulting from the adoption were: • The adoption resulted in the deconsolidation of $8.6 billion of both assets and liabilities of certain mandatory privatized social security funds in which we provide asset management services. Prior to January 1, 2016, the funds were consolidated as VOEs and the funds were presented in separate account assets and liabilities in the consolidated statements of financial position. The deconsolidation did not have a material impact to our consolidated statements of operations and did not result in a cumulative effect of the change on retained earnings. • The adoption of the guidance resulted in consolidation of certain sponsored investment funds in which we provide asset management services. We consolidated $180.1 million of assets and $0.6 million of liabilities. Additionally, we recorded $179.5 million of redeemable noncontrolling interest related to these funds. The consolidation of these funds did not have a material impact to our consolidated statements of operations and did not result in a cumulative effect of the change on retained earnings. • We invest in partnerships and other funds. Prior to new accounting guidance certain of these investments were VOEs. Upon adoption of new accounting guidance, some of these investments are now considered VIEs. We are not the primary beneficiary of these VIEs. • We provide asset management and other services to certain investment structures for which we earn performance-based management fees. These structures were considered VIEs prior to new accounting guidance, and we had a variable interest. We were not the primary beneficiary of these entities as we did not have the obligation to absorb losses or the right to receive benefits of the entities that could be potentially significant to the VIE. Subsequent to new accounting guidance, we no longer consider our fees a variable interest for those investment structures where our fees are deemed to be commensurate with the services provided, consistent with fees for similar services negotiated at arms-length, and we do not have additional interests in the entity that would absorb a significant amount of the entity's expected losses and expected residual returns of the entity. Consolidated Variable Interest Entities Grantor Trusts We contributed undated subordinated floating rate notes to three grantor trusts. The trusts separated their cash flows by issuing an interest-only certificate and a residual certificate related to each note contributed. Each interest-only certificate entitles the holder to interest on the stated note for a specified term, while the residual certificate entitles the holder to interest payments subsequent to the term of the interest-only certificate and to all principal payments. We retained the interest-only certificates and the residual certificates were subsequently sold to third parties. We have determined these grantor trusts are VIEs due to insufficient equity to sustain them. We determined we are the primary beneficiary as a result of our contribution of securities into the trusts and our significant continuing interest in the trusts. Collateralized Private Investment Vehicles We invest in cash and synthetic collateralized debt obligations, collateralized bond obligations, collateralized loan obligations and other collateralized structures, which are VIEs due to insufficient equity to sustain the entities (collectively known as "collateralized private investment vehicles"). The performance of the notes of these synthetic structures is primarily linked to a synthetic portfolio by derivatives; each note has a specific loss attachment and detachment point. The notes and related derivatives are collateralized by a pool of permitted investments. The investments are held by a trustee and can only be liquidated to settle obligations of the trusts. These obligations primarily include derivatives and the notes due at maturity or termination of the trusts. We determined we are the primary beneficiary for one of these synthetic entities because we act as the investment manager of the underlying portfolio and we have the power to make decisions and to receive benefits and the obligation to absorb losses that could be potentially significant to the VIE. Commercial Mortgage-Backed Securities We sold commercial mortgage loans to a real estate mortgage investment conduit trust. The trust issued various commercial mortgage-backed securities ("CMBS") certificates using the cash flows of the underlying commercial mortgages it purchased. This is considered a VIE due to insufficient equity to sustain itself. We have determined we are the primary beneficiary as we retained the special servicing role for the assets within the trust as well as the ownership of the bond class that controls the unilateral kick-out rights of the special servicer. Mandatory Retirement Savings Funds We hold an equity interest in Chilean mandatory privatized social security funds in which we provide asset management services. We determined that the mandatory privatized social security funds, which also include contributions for voluntary pension savings, voluntary non-pension savings and compensation savings accounts, are VIEs. This is because the equity holders as a group lack the power, due to voting rights or similar rights, to direct the activities of the entity that most significantly impact the entity's economic performance and also because equity investors are protected from below-average market investment returns relative to the industry's return, due to a regulatory guarantee that we provide. Further we concluded that we are the primary beneficiary through our power to make decisions and our significant variable interest in the funds. The purpose of the funds, which reside in legally segregated entities, is to provide long-term retirement savings. The obligation to the customer is directly related to the assets held in the funds and, as such, we present the assets as separate account assets and the obligation as separate account liabilities within our consolidated statements of financial position. Principal International Hong Kong offers retirement pension schemes in which we provide trustee, administration and asset management services to employers and employees under the Hong Kong MPF and ORSO pension schemes. Each pension scheme has various guaranteed and non-guaranteed constituent funds, or investment options, in which customers can invest their money. The guaranteed funds provide either a guaranteed rate of return to the customer or a minimum guarantee on withdrawals under certain qualifying events. We have determined the guaranteed funds are VIEs due to the fact the equity holders, as a group, lack the obligation to absorb expected losses due to the guarantee we provide. We concluded that we are the primary beneficiary because we have the power to make decisions and to receive benefits and the obligation to absorb losses that could be potentially significant to the VIE. Therefore, we consolidate the underlying assets and liabilities of the funds and present as separate accounts or within the general account, depending on the terms of the guarantee. Real Estate We invest in several real estate limited partnerships and limited liability companies. The entities invest in real estate properties. Certain of these entities are VIEs based on the combination of our significant economic interest and related voting rights. We determined we are the primary beneficiary as a result of our power to control the entities through our significant ownership. Due to the nature of these real estate investments, the investment balance will fluctuate as we purchase and sell interests in the entities and as capital expenditures are made to improve the underlying real estate. Sponsored Investment Funds We sponsor and invest in certain investment funds for which we provide asset management services. Although our asset management fee is commensurate with the services provided and consistent with fees for similar services negotiated at arms-length, we have a variable interest for funds where our other interests are more than insignificant. The funds are VIEs as the equity holders lack power through voting rights to direct the activities of the entity that most significantly impact its economic performance. We determined we are the primary beneficiary of the VIEs where our interest in the entity is more than insignificant and we are the asset manager. Assets and Liabilities of Consolidated Variable Interest Entities The carrying amounts of our consolidated VIE assets, which can only be used to settle obligations of consolidated VIEs, and liabilities of consolidated VIEs for which creditors do not have recourse were as follows: December 31, 2016 December 31, 2015 Total Total Total Total (in millions) Grantor trusts (1) $ $ $ $ Collateralized private investment vehicles (2) CMBS — — Mandatory retirement savings funds (3) Real estate (4) Sponsored investment funds (5) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The assets of grantor trusts are primarily fixed maturities, available-for-sale. The liabilities are primarily other liabilities that reflect an embedded derivative of the forecasted transaction to deliver the underlying securities. (2) The assets of the collateralized private investment vehicles are primarily fixed maturities, trading. The liabilities include derivative liabilities and an obligation to redeem notes at maturity or termination of the trusts, which are reported in other liabilities. (3) The assets of the mandatory retirement savings funds include separate account assets and equity securities, trading. The liabilities include separate account liabilities and contractholder funds. (4) The assets of the real estate VIEs primarily include real estate, other investments and cash. Liabilities primarily include other liabilities. Liabilities also included long-term debt as of December 31, 2015. (5) The assets of sponsored investment funds are primarily fixed maturities and equity securities reported in other investments and cash. The consolidated statements of financial position included a $58.8 million redeemable noncontrolling interest for sponsored investment funds as of December 31, 2016. Unconsolidated Variable Interest Entities Invested Securities We hold a variable interest in a number of VIEs where we are not the primary beneficiary. Our investments in these VIEs are reported in fixed maturities, available-for-sale; fixed maturities, trading; equity securities, trading and other investments in the consolidated statements of financial position and are described below. Unconsolidated VIEs include certain CMBS, residential mortgage-backed pass-through securities ("RMBS") and other ABS. All of these entities were deemed VIEs because the equity within these entities is insufficient to sustain them. We determined we are not the primary beneficiary in the entities within these categories of investments. This determination was based primarily on the fact we do not own the class of security that controls the unilateral right to replace the special servicer or equivalent function. As previously discussed, we invest in several types of collateralized private investment vehicles, which are VIEs. These include cash and synthetic structures that we do not manage. We have determined we are not the primary beneficiary of these collateralized private investment vehicles primarily because we do not control the economic performance of the entities and were not involved with the design of the entities. We have invested in various VIE trusts as a debt holder. All of these entities are classified as VIEs due to insufficient equity to sustain them. We have determined we are not the primary beneficiary primarily because we do not control the economic performance of the entities and were not involved with the design of the entities. We have invested in partnerships and other funds, which are classified as VIEs. The entities are VIEs as equity holders lack the power to control the most significant activities of the entities because the equity holders do not have either the ability by a simple majority to exercise substantive kick-out rights or substantive participating rights. We have determined we are not the primary beneficiary because we do not have the power to direct the most significant activities of the entities. We hold an equity interest in Mexican mandatory privatized social security funds in which we provide asset management services. Our equity interest in the funds is considered a variable interest. We concluded the funds are VIEs because the equity holders as a group lack decision-making ability through their voting rights. We are not the primary beneficiary of the VIEs because although we, as the asset manager, have the power to direct the activities of the VIEs, we do not have a potentially significant variable interest in the funds. The carrying value and maximum loss exposure for our unconsolidated VIEs were as follows: Asset carrying value Maximum exposure to (in millions) December 31, 2016 Fixed maturities, available-for-sale: Corporate $ $ Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations Fixed maturities, trading: Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Equity securities, trading Other investments: Other limited partnership and fund interests December 31, 2015 Fixed maturities, available-for-sale: Corporate $ $ Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations Fixed maturities, trading: Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other investments: Other limited partnership and fund interests (1) Our risk of loss is limited to our initial investment measured at amortized cost for fixed maturities, available-for-sale. Our risk of loss is limited to our investment measured at fair value for our fixed maturities, trading and equity securities, trading. Our risk of loss is limited to our carrying value plus any unfunded commitments and/or guarantees for our other investments. Unfunded commitments are not liabilities on our consolidated statements of financial position because we are only required to fund additional equity when called upon to do so by the general partner or investment manager. Money Market Funds We are the investment manager for certain money market mutual funds. Prior to new accounting guidance effective January 1, 2016, these funds were deemed to be VIEs. Under the prior guidance we were not considered the primary beneficiary of these VIEs since our involvement is limited primarily to being a service provider, and our variable interest does not absorb the majority of the variability of the entities' net assets. Effective January 1, 2016, new accounting guidance provides a scope exception for money market funds registered under Rule 2a-7 of the Investment Company Act of 1940 or similar funds. The scope exception eliminates the requirement to assess money market mutual funds under any consolidation model. As of December 31, 2016 and December 31, 2015, these funds held $0.8 billion and $1.3 billion in total assets, respectively. We have no contractual obligation to contribute to the funds; however, we provided support to these money market mutual funds through the waiver of fees and expense reimbursements. The amount of fees waived and expenses reimbursed was insignificant.

Investments

Investments	12 Months Ended
	Dec. 31, 2016
Investments
Investments	4. Investments Fixed Maturities and Equity Securities The amortized cost, gross unrealized gains and losses, other-than-temporary impairments in AOCI and fair value of fixed maturities and equity securities available-for-sale were as follows: Amortized Gross Gross Fair value Other-than- (in millions) December 31, 2016 Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ $ — Non-U.S. governments — States and political subdivisions Corporate Residential mortgage-backed pass-through securities — Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ $ — Non-U.S. governments — States and political subdivisions — Corporate Residential mortgage-backed pass-through securities — Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Excludes $120.9 million and $131.5 million as of December 31, 2016 and December 31, 2015, respectively, of net unrealized gains on impaired fixed maturities, available-for-sale related to changes in fair value subsequent to the impairment date, which are included in gross unrealized gains and gross unrealized losses. The amortized cost and fair value of fixed maturities available-for-sale as of December 31, 2016, by expected maturity, were as follows: Amortized Fair (in millions) Due in one year or less $ $ Due after one year through five years Due after five years through ten years Due after ten years ​ ​ ​ ​ ​ ​ ​ ​ Subtotal Mortgage-backed and other asset-backed securities ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Actual maturities may differ because borrowers may have the right to call or prepay obligations. Our portfolio is diversified by industry, issuer and asset class. Credit concentrations are managed to established limits. Net Investment Income Major components of net investment income were as follows: For the year ended 2016 2015 2014 (in millions) Fixed maturities, available-for-sale $ $ $ Fixed maturities, trading Equity securities, available-for-sale Equity securities, trading Mortgage loans Real estate Policy loans Cash and cash equivalents Derivatives (1) ) ) ) Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Investment expenses ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net investment income $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Relates to periodic settlements of derivatives used in fair value and cash flow hedges of fixed maturities, available-for-sale. See Note 5, Derivative Financial Instruments, for further details. Net Realized Capital Gains and Losses Major components of net realized capital gains (losses) on investments were as follows: For the year ended 2016 2015 2014 (in millions) Fixed maturities, available-for-sale: Gross gains $ $ $ Gross losses ) ) ) Net impairment losses ) ) ) Hedging, net ) ) ) Fixed maturities, trading ) Equity securities, available-for-sale: Gross gains — Gross losses — ) ) Net impairment (losses) recoveries ) Equity securities, trading ) Mortgage loans ) ) Derivatives Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Proceeds from sales of investments (excluding call and maturity proceeds) in fixed maturities, available-for-sale were $1,916.9 million, $1,537.5 million and $2,251.2 million in 2016, 2015 and 2014, respectively. Other-Than-Temporary Impairments We have a process in place to identify fixed maturity and equity securities that could potentially have an impairment that is other than temporary. This process involves monitoring market events that could impact issuers' credit ratings, business climate, management changes, litigation and government actions and other similar factors. This process also involves monitoring late payments, pricing levels, downgrades by rating agencies, key financial ratios, financial statements, revenue forecasts and cash flow projections as indicators of credit issues. Each reporting period, all securities are reviewed to determine whether an other-than-temporary decline in value exists and whether losses should be recognized. We consider relevant facts and circumstances in evaluating whether a credit or interest rate-related impairment of a security is other than temporary. Relevant facts and circumstances considered include: (1) the extent and length of time the fair value has been below cost; (2) the reasons for the decline in value; (3) the financial position and access to capital of the issuer, including the current and future impact of any specific events; (4) for structured securities, the adequacy of the expected cash flows; (5) for fixed maturities, our intent to sell a security or whether it is more likely than not we will be required to sell the security before the recovery of its amortized cost which, in some cases, may extend to maturity and (6) for equity securities, our ability and intent to hold the security for a period of time that allows for the recovery in value. To the extent we determine a security is deemed to be other than temporarily impaired, an impairment loss is recognized. Impairment losses on equity securities are recognized in net income and are measured as the difference between amortized cost and fair value. The way in which impairment losses on fixed maturities are recognized in the financial statements is dependent on the facts and circumstances related to the specific security. If we intend to sell a security or it is more likely than not that we would be required to sell a security before the recovery of its amortized cost, we recognize an other-than-temporary impairment in net income for the difference between amortized cost and fair value. If we do not expect to recover the amortized cost basis, we do not plan to sell the security and if it is not more likely than not that we would be required to sell a security before the recovery of its amortized cost, the recognition of the other-than-temporary impairment is bifurcated. We recognize the credit loss portion in net income and the noncredit loss portion in OCI ("bifurcated OTTI"). Total other-than-temporary impairment losses, net of recoveries from the sale of previously impaired securities, were as follows: For the year ended 2016 2015 2014 (in millions) Fixed maturities, available-for-sale $ ) $ ) $ Equity securities, available-for-sale ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other-than-temporary impairment losses, net of recoveries from the sale of previously impaired securities ) ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) OCI (1) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Represents the net impact of (a) gains resulting from reclassification of noncredit impairment losses for fixed maturities with bifurcated OTTI from net realized capital gains (losses) to OCI and (b) losses resulting from reclassification of previously recognized noncredit impairment losses from OCI to net realized capital gains (losses) for fixed maturities with bifurcated OTTI that had additional credit losses or fixed maturities that previously had bifurcated OTTI that have now been sold or are intended to be sold. We estimate the amount of the credit loss component of a fixed maturity security impairment as the difference between amortized cost and the present value of the expected cash flows of the security. The present value is determined using the best estimate cash flows discounted at the effective interest rate implicit to the security at the date of purchase or the current yield to accrete an asset-backed or floating rate security. The methodology and assumptions for establishing the best estimate cash flows vary depending on the type of security. The ABS cash flow estimates are based on security specific facts and circumstances that may include collateral characteristics, expectations of delinquency and default rates, loss severity and prepayment speeds and structural support, including subordination and guarantees. The corporate security cash flow estimates are derived from scenario-based outcomes of expected corporate restructurings or liquidations using bond specific facts and circumstances including timing, security interests and loss severity. The following table provides a rollforward of accumulated credit losses for fixed maturities with bifurcated credit losses. The purpose of the table is to provide detail of (1) additions to the bifurcated credit loss amounts recognized in net realized capital gains (losses) during the period and (2) decrements for previously recognized bifurcated credit losses where the loss is no longer bifurcated and/or there has been a positive change in expected cash flows or accretion of the bifurcated credit loss amount. For the year ended 2016 2015 2014 (in millions) Beginning balance $ ) $ ) $ ) Credit losses for which an other-than-temporary impairment was not previously recognized ) ) ) Credit losses for which an other-than-temporary impairment was previously recognized ) ) ) Reduction for credit losses previously recognized on fixed maturities now sold, paid down or intended to be sold Net reduction for positive changes in cash flows expected to be collected and amortization (1) Foreign currency translation adjustment ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Amounts are recognized in net investment income. Gross Unrealized Losses for Fixed Maturities and Equity Securities For fixed maturities and equity securities available-for-sale with unrealized losses, including other-than-temporary impairment losses reported in OCI, the gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position were as follows: December 31, 2016 Less than twelve Greater than or Total Fair Gross Fair Gross Fair Gross (in millions) Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ — $ $ Non-U.S. governments States and political subdivisions Corporate Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Of the total amounts, Principal Life's consolidated portfolio represented $16,918.9 million in available-for-sale fixed maturities with gross unrealized losses of $615.1 million. Of those fixed maturity securities in Principal Life's consolidated portfolio with a gross unrealized loss position, 94% were investment grade (rated AAA through BBB-) with an average price of 96 (carrying value/amortized cost) as of December 31, 2016. Gross unrealized losses in our fixed maturities portfolio decreased during the year ended December 31, 2016, primarily due to tightening of credit spreads, partially offset by an increase in interest rates. For those securities that had been in a continuous unrealized loss position for less than twelve months, Principal Life's consolidated portfolio held 1,911 securities with a carrying value of $14,549.4 million and unrealized losses of $384.6 million reflecting an average price of 97 as of December 31, 2016. Of this portfolio, 98% was investment grade (rated AAA through BBB–) as of December 31, 2016, with associated unrealized losses of $374.1 million. The unrealized losses on these securities can primarily be attributed to changes in market interest rates and changes in credit spreads since the securities were acquired. For those securities that had been in a continuous unrealized loss position greater than or equal to twelve months, Principal Life's consolidated portfolio held 453 securities with a carrying value of $2,369.5 million and unrealized losses of $230.5 million. The average credit rating of this portfolio was A– with an average price of 91 as of December 31, 2016. Of the $230.5 million in unrealized losses, the corporate sector accounts for $141.9 million in unrealized losses with an average price of 89 and an average credit rating of BBB–. The remaining unrealized losses consist primarily of $46.9 million within the commercial mortgage-backed securities sector with an average price of 93 and an average credit rating of AA–. The unrealized losses on these securities can primarily be attributed to changes in market interest rates and changes in credit spreads since the securities were acquired. Because we expected to recover our amortized cost, it was not our intent to sell the fixed maturity available-for-sale securities with unrealized losses and it was not more likely than not that we would be required to sell these securities before recovery of the amortized cost, which may be maturity, we did not consider these investments to be other-than-temporarily impaired as of December 31, 2016. December 31, 2015 Less than twelve Greater than or Total Fair Gross Fair Gross Fair Gross (in millions) Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ $ $ Non-U.S. governments States and political subdivisions Corporate Residential mortgage-backed pass- through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Of the total amounts, Principal Life's consolidated portfolio represented $15,980.0 million in available-for-sale fixed maturities with gross unrealized losses of $777.0 million. Of those fixed maturity securities in Principal Life's consolidated portfolio with a gross unrealized loss position, 87% were investment grade (rated AAA through BBB–) with an average price of 95 (carrying value/amortized cost) as of December 31, 2015. Gross unrealized losses in our fixed maturities portfolio increased during the year ended December 31, 2015, primarily due to an increase in interest rates and widening of credit spreads. For those securities that had been in a continuous unrealized loss position for less than twelve months, Principal Life's consolidated portfolio held 1,725 securities with a carrying value of $13,673.9 million and unrealized losses of $376.3 million reflecting an average price of 97 as of December 31, 2015. Of this portfolio, 90% was investment grade (rated AAA through BBB–) as of December 31, 2015, with associated unrealized losses of $298.1 million. The unrealized losses on these securities can primarily be attributed to changes in market interest rates and changes in credit spreads since the securities were acquired. For those securities that had been in a continuous unrealized loss position greater than or equal to twelve months, Principal Life's consolidated portfolio held 404 securities with a carrying value of $2,306.1 million and unrealized losses of $400.7 million. The average credit rating of this portfolio was BBB+ with an average price of 85 as of December 31, 2015. Of the $400.7 million in unrealized losses, the corporate sector accounts for $304.2 million in unrealized losses with an average price of 80 and an average credit rating of BBB–. The remaining unrealized losses consist primarily of $50.7 million within the commercial mortgage-backed securities sector with an average price of 86 and an average credit rating of BBB+. The unrealized losses on these securities can primarily be attributed to changes in market interest rates and changes in credit spreads since the securities were acquired. Because we expected to recover our amortized cost, it was not our intent to sell the fixed maturity available-for-sale securities with unrealized losses and it was not more likely than not that we would be required to sell these securities before recovery of the amortized cost, which may be maturity, we did not consider these investments to be other-than-temporarily impaired as of December 31, 2015. Net Unrealized Gains and Losses on Available-for-Sale Securities and Derivative Instruments The net unrealized gains and losses on investments in available-for-sale securities, the noncredit component of impairment losses on fixed maturities available-for-sale and the net unrealized gains and losses on derivative instruments in cash flow hedge relationships are reported as separate components of stockholders' equity. The cumulative amount of net unrealized gains and losses on available-for-sale securities and derivative instruments in cash flow hedge relationships net of adjustments related to DAC and related actuarial balances and applicable income taxes was as follows: December 31, 2016 December 31, 2015 (in millions) Net unrealized gains on fixed maturities, available-for-sale (1) $ $ Noncredit component of impairment losses on fixed maturities, available-for-sale ) ) Net unrealized losses on equity securities, available-for-sale ) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ) Net unrealized gains on derivative instruments Net unrealized gains on equity method subsidiaries and noncontrolling interest adjustments Provision for deferred income taxes ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on available-for-sale securities and derivative instruments $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Excludes net unrealized gains (losses) on fixed maturities, available-for-sale included in fair value hedging relationships. Mortgage Loans Mortgage loans consist of commercial and residential mortgage loans. We evaluate risks inherent in our commercial mortgage loans in two classes: (1) brick and mortar property loans, including mezzanine loans, where we analyze the property's rent payments as support for the loan, and (2) credit tenant loans ("CTL"), where we rely on the credit analysis of the tenant for the repayment of the loan. We evaluate risks inherent in our residential mortgage loan portfolio in two classes: (1) home equity mortgages and (2) first lien mortgages. The carrying amount of our mortgage loan portfolio was as follows: December 31, 2016 December 31, 2015 (in millions) Commercial mortgage loans $ $ Residential mortgage loans ​ ​ ​ ​ ​ ​ ​ ​ Total amortized cost Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total carrying value $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ We periodically purchase mortgage loans as well as sell mortgage loans we have originated. Mortgage loans purchased and sold were as follows: For the year ended 2016 2015 2014 (in millions) Commercial mortgage loans: Purchased $ $ $ Sold Residential mortgage loans: Purchased Sold Our commercial mortgage loan portfolio consists primarily of non-recourse, fixed rate mortgages on stabilized properties. Our commercial mortgage loan portfolio is diversified by geographic region and specific collateral property type as follows: December 31, 2016 December 31, 2015 Amortized Percent Amortized Percent ($ in millions) Geographic distribution New England $ % $ % Middle Atlantic East North Central West North Central South Atlantic East South Central West South Central Mountain Pacific International ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ % $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Property type distribution Office $ % $ % Retail Industrial Apartments Hotel Mixed use/other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ % $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Our residential mortgage loan portfolio is composed of home equity mortgages with an amortized cost of $165.6 million and $218.8 million and first lien mortgages with an amortized cost of $1,054.3 million and $906.9 million as of December 31, 2016 and December 31, 2015, respectively. Our residential home equity mortgages are concentrated in the United States and are generally second lien mortgages comprised of closed-end loans and lines of credit. Our first lien loans are concentrated in Chile and the United States. Mortgage Loan Credit Monitoring Commercial Credit Risk Profile Based on Internal Rating We actively monitor and manage our commercial mortgage loan portfolio. All commercial mortgage loans are analyzed regularly and substantially all are internally rated, based on a proprietary risk rating cash flow model, in order to monitor the financial quality of these assets. The model stresses expected cash flows at various levels and at different points in time depending on the durability of the income stream, which includes our assessment of factors such as location (macro and micro markets), tenant quality and lease expirations. Our internal rating analysis presents expected losses in terms of an S&P Global ("S&P") bond equivalent rating. As the credit risk for commercial mortgage loans increases, we adjust our internal ratings downward with loans in the category "B+ and below" having the highest risk for credit loss. Internal ratings on commercial mortgage loans are updated at least annually and potentially more often for certain loans with material changes in collateral value or occupancy and for loans on an internal "watch list". Commercial mortgage loans that require more frequent and detailed attention than other loans in our portfolio are identified and placed on an internal "watch list". Among the criteria that would indicate a potential problem are significant negative changes in ratios of loan to value or contract rents to debt service, major tenant vacancies or bankruptcies, borrower sponsorship problems, late payments, delinquent taxes and loan relief/restructuring requests. The amortized cost of our commercial mortgage loan portfolio by credit risk, as determined by our internal rating system expressed in terms of an S&P bond equivalent rating, was as follows: December 31, 2016 Brick and mortar CTL Total (in millions) A– and above $ $ $ BBB+ thru BBB– BB+ thru BB– — B+ and below ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Brick and mortar CTL Total (in millions) A– and above $ $ $ BBB+ thru BBB– BB+ thru BB– B+ and below ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Residential Credit Risk Profile Based on Performance Status Our residential mortgage loan portfolio is monitored based on performance of the loans. Monitoring on a residential mortgage loan increases when the loan is delinquent or earlier if there is an indication of potential impairment. We define non-performing residential mortgage loans as loans 90 days or greater delinquent or on non-accrual status. The amortized cost of our performing and non-performing residential mortgage loans was as follows: December 31, 2016 Home equity First liens Total (in millions) Performing $ $ $ Non-performing ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Home equity First liens Total (in millions) Performing $ $ $ Non-performing ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-Accrual Mortgage Loans Commercial and residential mortgage loans are placed on non-accrual status if we have concern regarding the collectability of future payments or if a loan has matured without being paid off or extended. Factors considered may include conversations with the borrower, loss of major tenant, bankruptcy of borrower or major tenant, decreased property cash flow for commercial mortgage loans or number of days past due and other circumstances for residential mortgage loans. Based on an assessment as to the collectability of the principal, a determination is made to apply any payments received either against the principal or according to the contractual terms of the loan. When a loan is placed on non-accrual status, the accrued unpaid interest receivable is reversed against interest income. Accrual of interest resumes after factors resulting in doubts about collectability have improved. Residential first lien mortgages in the Chilean market are carried on accrual for a longer period of delinquency than domestic loans, as assessment of collectability is based on the nature of the loans and collection practices in that market. The amortized cost of mortgage loans on non-accrual status was as follows: December 31, 2016 December 31, 2015 (in millions) Residential: Home equity $ $ First liens ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The aging of our mortgage loans, based on amortized cost, was as follows: December 31, 2016 30 - 59 days 60 - 89 days 90 days or Total Current Total Recorded (in millions) Commercial-brick and mortar $ — $ — $ — $ — $ $ $ — Commercial-CTL — — — — — Residential-home equity — Residential-first liens ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 30 - 59 days 60 - 89 days 90 days or Total Current Total Recorded (in millions) Commercial-brick and mortar $ — $ — $ — $ — $ $ $ — Commercial-CTL — — — — — Residential-home equity — Residential-first liens ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mortgage Loan Valuation Allowance We establish a valuation allowance to provide for the risk of credit losses inherent in our portfolio. The valuation allowance includes loan specific reserves for loans that are deemed to be impaired as well as reserves for pools of loans with similar risk characteristics where a property risk or market specific risk has not been identified but for which we anticipate a loss may occur. Mortgage loans on real estate are considered impaired when, based on current information and events, it is probable we will be unable to collect all amounts due according to contractual terms of the loan agreement. When we determine a loan is impaired, a valuation allowance is established equal to the difference between the carrying amount of the mortgage loan and the estimated value reduced by the cost to sell. Estimated value is based on either the present value of the expected future cash flows discounted at the loan's effective interest rate, the loan's observable market price or fair value of the collateral. Subsequent changes in the estimated value are reflected in the valuation allowance. Amounts on loans deemed to be uncollectible are charged off and removed from the valuation allowance. The change in the valuation allowance provision is included in net realized capital gains (losses) on our consolidated statements of operations. The valuation allowance is maintained at a level believed adequate by management to absorb estimated probable credit losses. Management's periodic evaluation and assessment of the valuation allowance adequacy is based on known and inherent risks in the portfolio, adverse situations that may affect a borrower's ability to repay, the estimated value of the underlying collateral, composition of the loan portfolio, portfolio delinquency information, underwriting standards, peer group information, current economic conditions, loss experience and other relevant factors. The evaluation of our impaired loan component is subjective, as it requires the estimation of timing and amount of future cash flows expected to be received on impaired loans. We review our commercial mortgage loan portfolio and analyze the need for a valuation allowance for any loan that is delinquent for 60 days or more, in process of foreclosure, restructured, on the internal "watch list" or that currently has a valuation allowance. In addition to establishing allowance levels for specifically identified impaired commercial mortgage loans, management determines an allowance for all other loans in the portfolio for which historical experience and current economic conditions indicate certain losses exist. These loans are segregated by risk rating level with an estimated loss ratio applied against each risk rating level. The loss ratio is generally based upon historical loss experience for each risk rating level as adjusted for certain current environmental factors management believes to be relevant. For our residential mortgage loan portfolio, we separate the loans into several homogeneous pools, each of which consist of loans of a similar nature including but not limited to loans similar in collateral, term and structure and loan purpose or type. We evaluate loan pools based on aggregated risk ratings, estimated specific loss potential in the different classes of credits, and historical loss experience by pool type. We adjust these quantitative factors for qualitative factors of present conditions. Qualitative factors include items such as economic and business conditions, changes in the portfolio, value of underlying collateral and concentrations. Residential mortgage loan pools exclude loans that have been restructured or impaired, as those loans are evaluated individually. A rollforward of our valuation allowance and ending balances of the allowance and loan balance by basis of impairment method was as follows: Commercial Residential Total (in millions) For the year ended December 31, 2016 Beginning balance $ $ $ Provision ) ) Charge-offs ) ) ) Recoveries — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2015 Beginning balance $ $ $ Provision — Charge-offs ) ) ) Recoveries Effect of exchange rates — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2014 Beginning balance $ $ $ Provision ) Charge-offs ) ) ) Recoveries — Effect of exchange rates — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan balance by basis of impairment method: Individually evaluated for impairment $ $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Impaired Mortgage Loans Impaired mortgage loans are loans with a related specific valuation allowance, loans whose carrying amount has been reduced to the expected collectible amount because the impairment has been considered other than temporary or a loan modification has been classified as a troubled debt restructuring ("TDR"). Based on an assessment as to the collectability of the principal, a determination is made to apply any payments received either against the principal or according to th

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2016
Derivative Financial Instruments
Derivative Financial Instruments	5. Derivative Financial Instruments Derivatives are generally used to hedge or reduce exposure to market risks associated with assets held or expected to be purchased or sold and liabilities incurred or expected to be incurred. Derivatives are used to change the characteristics of our asset/liability mix consistent with our risk management activities. Derivatives are also used in asset replication strategies. Types of Derivative Instruments Interest Rate Contracts Interest rate risk is the risk we will incur economic losses due to adverse changes in interest rates. Sources of interest rate risk include the difference between the maturity and interest rate changes of assets with the liabilities they support, timing differences between the pricing of liabilities and the purchase or procurement of assets and changing cash flow profiles from original projections due to prepayment options embedded within asset and liability contracts. We use various derivatives to manage our exposure to fluctuations in interest rates. Interest rate swaps are contracts in which we agree with other parties to exchange, at specified intervals, the difference between fixed rate and floating rate interest amounts based upon designated market rates or rate indices and an agreed upon notional principal amount. Generally, no cash is exchanged at the outset of the contract and no principal payments are made by any party. Cash is paid or received based on the terms of the swap. We use interest rate swaps primarily to more closely match the interest rate characteristics of assets and liabilities and to mitigate the risks arising from timing mismatches between assets and liabilities (including duration mismatches). We also use interest rate swaps to hedge against changes in the value of assets we anticipate acquiring and other anticipated transactions and commitments. Interest rate swaps are used to hedge against changes in the value of the guaranteed minimum withdrawal benefit ("GMWB") liability. The GMWB rider on our variable annuity products provides for guaranteed minimum withdrawal benefits regardless of the actual performance of various equity and/or fixed income funds available with the product. Interest rate options, including interest rate caps and interest rate floors, which can be combined to form interest rate collars, are contracts that entitle the purchaser to pay or receive the amounts, if any, by which a specified market rate exceeds a cap strike interest rate, or falls below a floor strike interest rate, respectively, at specified dates. We use interest rate collars to manage interest rate risk related to guaranteed minimum interest rate liabilities in our individual annuities contracts and lapse risk associated with higher interest rates. A swaption is an option to enter into an interest rate swap at a future date. We purchase swaptions to offset or modify existing exposures. Swaptions provide us the benefit of the agreed-upon strike rate if the market rates for liabilities are higher, with the flexibility to enter into the current market rate swap if the market rates for liabilities are lower. Swaptions not only hedge against the downside risk, but also allow us to take advantage of any upside benefits. In exchange-traded futures transactions, we agree to purchase or sell a specified number of contracts, the values of which are determined by the values of designated classes of securities, and to post variation margin on a daily basis in an amount equal to the difference in the daily market values of those contracts. We enter into exchange-traded futures with regulated futures commissions merchants who are members of a trading exchange. We have used exchange-traded futures to reduce market risks from changes in interest rates and to alter mismatches between the assets in a portfolio and the liabilities supported by those assets. Foreign Exchange Contracts Foreign currency risk is the risk we will incur economic losses due to adverse fluctuations in foreign currency exchange rates. This risk arises from foreign currency-denominated funding agreements we issue, foreign currency-denominated fixed maturity and equity securities we invest in, capital transactions with our international operations and the financial results of our international operations. We use various derivatives to manage our exposure to fluctuations in foreign currency exchange rates. Currency swaps are contracts in which we agree with other parties to exchange, at specified intervals, a series of principal and interest payments in one currency for that of another currency. Generally, the principal amount of each currency is exchanged at the beginning and termination of the currency swap by each party. The interest payments are primarily fixed-to-fixed rate; however, they may also be fixed-to-floating rate or floating-to-fixed rate. These transactions are entered into pursuant to master agreements that provide for a single net payment to be made by one counterparty for payments made in the same currency at each due date. We use currency swaps to reduce market risks from changes in currency exchange rates with respect to investments or liabilities denominated in foreign currencies that we either hold or intend to acquire or sell. Currency forwards are contracts in which we agree with other parties to deliver or receive a specified amount of an identified currency at a specified future date. Typically, the price is agreed upon at the time of the contract and payment for such a contract is made at the specified future date. We use currency forwards to reduce market risks from changes in currency exchange rates with respect to investments or liabilities denominated in foreign currencies that we either hold or intend to acquire or sell. We sometimes use currency forwards to hedge the currency risk associated with a business combination or to hedge certain net equity investments in or expected cash flows from our foreign operations. Equity Contracts Equity risk is the risk that we will incur economic losses due to adverse fluctuations in common stock prices. We use various derivatives to manage our exposure to equity risk, which arises from products in which the interest we credit is tied to an external equity index as well as products subject to minimum contractual guarantees. We purchase equity call spreads to hedge the equity participation rates promised to contractholders in conjunction with our fixed deferred annuity and universal life products that credit interest based on changes in an external equity index. We use exchange-traded futures and equity put options to hedge against changes in the value of the GMWB liability related to the GMWB rider on our variable annuity product, as previously explained. The premium associated with certain options is paid quarterly over the life of the option contract. Credit Contracts Credit risk relates to the uncertainty associated with the continued ability of a given obligor to make timely payments of principal and interest. We use credit default swaps to enhance the return on our investment portfolio by providing comparable exposure to fixed income securities that might not be available in the primary market. They are also used to hedge credit exposures in our investment portfolio. Credit derivatives are used to sell or buy credit protection on an identified name or names on an unfunded or synthetic basis in return for receiving or paying a quarterly premium. The premium generally corresponds to a referenced name's credit spread at the time the agreement is executed. In cases where we sell protection, we also buy a quality cash bond to match against the credit default swap, thereby entering into a synthetic transaction replicating a cash security. When selling protection, if there is an event of default by the referenced name, as defined by the agreement, we are obligated to pay the counterparty the referenced amount of the contract and receive in return the referenced security in a principal amount equal to the notional value of the credit default swap. Total return swaps are contracts in which we agree with other parties to exchange, at specified intervals, an amount determined by the difference between the previous price and the current price of a reference asset based upon an agreed upon notional principal amount plus an additional amount determined by the financing spread. We currently use futures traded on an exchange ("exchange-traded") and total return swaps referencing equity indices to hedge our portfolio from potential credit losses related to systemic events. Other Contracts Embedded Derivatives. We purchase or issue certain financial instruments or products that contain a derivative instrument that is embedded in the financial instrument or product. When it is determined that the embedded derivative possesses economic characteristics that are not clearly or closely related to the economic characteristics of the host contract and a separate instrument with the same terms would qualify as a derivative instrument, the embedded derivative is bifurcated from the host instrument for measurement purposes. The embedded derivative, which is reported with the host instrument in the consolidated statements of financial position, is carried at fair value. We have investment contracts in which the return is tied to a leveraged inflation index. We economically hedge the risk associated with these investment contracts. We offer group annuity contracts that have guaranteed separate accounts as an investment option. We also offer funds with embedded fixed-rate guarantees as investment options in our defined contribution plans in Hong Kong. We have structured investment relationships with trusts we have determined to be VIEs, which are consolidated in our financial statements. The notes issued by these trusts include obligations to deliver an underlying security to residual interest holders and the obligations contain an embedded derivative of the forecasted transaction to deliver the underlying security. We have fixed deferred annuities and universal life contracts that credit interest based on changes in an external equity index. We also have certain variable annuity products with a GMWB rider, which allows the customer to make withdrawals of a specified annual amount, either for a fixed number of years or for the lifetime of the customer, even if the account value is fully exhausted. Declines in the equity markets may increase our exposure to benefits under contracts with the GMWB. We economically hedge the exposure in these contracts, as previously explained. Exposure Our risk of loss is typically limited to the fair value of our derivative instruments and not to the notional or contractual amounts of these derivatives. We are also exposed to credit losses in the event of nonperformance of the counterparties. Our current credit exposure is limited to the value of derivatives that have become favorable to us. This credit risk is minimized by purchasing such agreements from financial institutions with high credit ratings and by establishing and monitoring exposure limits. We also utilize various credit enhancements, including collateral and credit triggers to reduce the credit exposure to our derivative instruments. Derivatives may be exchange-traded or they may be privately negotiated contracts, which are usually referred to as over-the-counter ("OTC") derivatives. Certain of our OTC derivatives are cleared and settled through central clearing counterparties ("OTC cleared"), while others are bilateral contracts between two counterparties ("bilateral OTC"). Our derivative transactions are generally documented under International Swaps and Derivatives Association, Inc. ("ISDA") Master Agreements. Management believes that such agreements provide for legally enforceable set-off and close-out netting of exposures to specific counterparties. Under such agreements, in connection with an early termination of a transaction, we are permitted to set off our receivable from a counterparty against our payables to the same counterparty arising out of all included transactions. For reporting purposes, we do not offset fair value amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral against fair value amounts recognized for derivative instruments executed with the same counterparties under master netting agreements. We posted $322.4 million and $342.7 million in cash and securities under collateral arrangements as of December 31, 2016 and December 31, 2015, respectively, to satisfy collateral requirements associated with our derivative credit support agreements and FCM agreements. These amounts include initial margin requirements. Certain of our derivative instruments contain provisions that require us to maintain an investment grade rating from each of the major credit rating agencies on our debt. If the ratings on our debt were to fall below investment grade, it would be in violation of these provisions and the counterparties to the derivative instruments could request immediate payment or demand immediate and ongoing full overnight collateralization on derivative instruments in net liability positions. The aggregate fair value, inclusive of accrued interest, of all derivative instruments with credit-risk-related contingent features that were in a liability position without regard to netting under derivative credit support annex agreements as of December 31, 2016 and December 31, 2015, was $454.7 million and $606.5 million, respectively. Cleared derivatives have contingent features that require us to post excess margin as required by the FCM. The terms surrounding excess margin vary by FCM agreement. With respect to derivatives containing collateral triggers, we posted collateral and initial margin of $322.4 million and $342.7 million as of December 31, 2016 and December 31, 2015, respectively, in the normal course of business, which reflects netting under derivative agreements. If the credit-risk-related contingent features underlying these agreements were triggered on December 31, 2016, we would be required to post an additional $42.0 million of collateral to our counterparties. As of December 31, 2016 and December 31, 2015, we had received $576.3 million and $217.5 million, respectively, of cash collateral associated with our derivative credit support annex agreements and FCM agreements, for which we recorded a corresponding liability reflecting our obligation to return the collateral. Notional amounts are used to express the extent of our involvement in derivative transactions and represent a standard measurement of the volume of our derivative activity. Notional amounts represent those amounts used to calculate contractual flows to be exchanged and are not paid or received, except for contracts such as currency swaps. Credit exposure represents the gross amount owed to us under derivative contracts as of the valuation date. The notional amounts and credit exposure of our derivative financial instruments by type were as follows: December 31, 2016 December 31, 2015 (in millions) Notional amounts of derivative instruments Interest rate contracts: Interest rate swaps $ $ Interest rate options Interest rate futures Swaptions Foreign exchange contracts: Currency swaps Currency forwards Equity contracts: Equity options Equity futures Credit contracts: Credit default swaps Total return swaps Futures Other contracts: Embedded derivatives ​ ​ ​ ​ ​ ​ ​ ​ Total notional amounts at end of period $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Credit exposure of derivative instruments Interest rate contracts: Interest rate swaps $ $ Interest rate options Foreign exchange contracts: Currency swaps Currency forwards Equity contracts: Equity options Credit contracts: Credit default swaps Total return swaps ​ ​ ​ ​ ​ ​ ​ ​ Total gross credit exposure Less: collateral received ​ ​ ​ ​ ​ ​ ​ ​ Net credit exposure $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The fair value of our derivative instruments classified as assets and liabilities was as follows: Derivative assets (1) Derivative liabilities (2) December 31, 2016 December 31, 2015 December 31, 2016 December 31, 2015 (in millions) Derivatives designated as hedging instruments Interest rate contracts $ $ $ $ Foreign exchange contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total derivatives designated as hedging instruments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives not designated as hedging instruments Interest rate contracts $ $ $ $ Foreign exchange contracts Equity contracts Credit contracts Other contracts — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total derivatives not designated as hedging instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total derivative instruments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value of derivative assets is reported with other investments on the consolidated statements of financial position. (2) The fair value of derivative liabilities is reported with other liabilities on the consolidated statements of financial position, with the exception of certain embedded derivative liabilities. Embedded derivative liabilities with a fair value of $176.5 million and $177.4 million as of December 31, 2016 and December 31, 2015, respectively, are reported with contractholder funds on the consolidated statements of financial position. Credit Derivatives Sold When we sell credit protection, we are exposed to the underlying credit risk similar to purchasing a fixed maturity security instrument. The majority of our credit derivative contracts sold reference a single name or reference security (referred to as "single name credit default swaps"). The remainder of our credit derivatives reference either a basket or index of securities. These instruments are either referenced in an OTC credit derivative transaction or embedded within an investment structure that has been fully consolidated into our financial statements. These credit derivative transactions are subject to events of default defined within the terms of the contract, which normally consist of bankruptcy, failure to pay, or modified restructuring of the reference entity and/or issue. If a default event occurs for a reference name or security, we are obligated to pay the counterparty an amount equal to the notional amount of the credit derivative transaction. As a result, our maximum future payment is equal to the notional amount of the credit derivative. In certain cases, we also have purchased credit protection with identical underlyings to certain of our sold protection transactions. As of December 31, 2016 and December 31, 2015, we did not purchase credit protection relating to our sold protection transactions. In certain circumstances, our potential loss could also be reduced by any amount recovered in the default proceedings of the underlying credit name. We purchased an investment structure with embedded credit features that is fully consolidated into our financial statements. This consolidation results in recognition of the underlying credit derivatives and collateral within the structure, typically high quality fixed maturities that are owned by a special purpose vehicle. These credit derivatives reference several names in a basket structure. In the event of default, the collateral within the structure would typically be liquidated to pay the claims of the credit derivative counterparty. The following tables show our credit default swap protection sold by types of contract, types of referenced/underlying asset class and external agency rating for the underlying reference security. The maximum future payments are undiscounted and have not been reduced by the effect of any offsetting transactions, collateral or recourse features described above. December 31, 2016 Notional Fair Maximum Weighted (in millions) Single name credit default swaps Corporate debt AAA $ $ $ AA A BBB B ) Near default Government/municipalities AA Sovereign AA BBB ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total single name credit default swaps Basket and index credit default swaps Corporate debt Near default (1) ) Government/municipalities AA ) Structured finance AA — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total basket and index credit default swaps ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total credit default swap protection sold $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Notional Fair Maximum Weighted (in millions) Single name credit default swaps Corporate debt AAA $ $ $ AA A BBB ) BB ) CCC ) Government/municipalities AA Sovereign AA — BBB ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total single name credit default swaps ) Basket and index credit default swaps Corporate debt Near default (1) ) Government/municipalities AA ) Structured finance AAA — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total basket and index credit default swaps ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total credit default swap protection sold $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes $60.0 million and $78.0 million as of December 31, 2016 and December 31, 2015, respectively, notional of derivatives in consolidated collateralized private investment vehicle VIEs where the credit risk is borne by third party investors. We also have invested in fixed maturities classified as trading that contain credit default swaps. These securities are subject to the credit risk of the issuer, normally a special purpose vehicle, which consists of the underlying credit default swaps and high quality fixed maturities that serve as collateral. A default event occurs if the cumulative losses exceed a specified attachment point, which is typically not the first loss of the portfolio. If a default event occurs that exceeds the specified attachment point, our investment may not be fully returned. We would have no future potential payments under these investments. The following tables show, by the types of referenced/underlying asset class and external rating, our fixed maturities with embedded credit derivatives. December 31, 2016 Amortized Carrying Weighted (in millions) Structured finance AA $ $ BBB BB CCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total structured finance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities with credit derivatives $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Amortized Carrying Weighted (in millions) Corporate debt A $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total corporate debt Structured finance A BBB BB CCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total structured finance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities with credit derivatives $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Hedges We use fixed-to-floating rate interest rate swaps to more closely align the interest rate characteristics of certain assets and liabilities. In general, these swaps are used in asset and liability management to modify duration, which is a measure of sensitivity to interest rate changes. We enter into currency exchange swap agreements to convert certain foreign denominated assets and liabilities into U.S. dollar floating-rate denominated instruments to eliminate the exposure to future currency volatility on those items. The net interest effect of interest rate swap and currency swap transactions for derivatives in fair value hedges is recorded as an adjustment to income or expense of the underlying hedged item in our consolidated statements of operations. Hedge effectiveness testing for fair value relationships is performed utilizing a regression analysis approach for both prospective and retrospective evaluations. This regression analysis will consider multiple data points for the assessment that the hedge continues to be highly effective in achieving offsetting changes in fair value. In certain periods, the comparison of the change in value of the derivative and the change in the value of the hedged item may not be offsetting at a specific period in time due to small movements in value. However, any amounts recorded as fair value hedges have shown to be highly effective in achieving offsetting changes in fair value both for present and future periods. The following table shows the effect of derivatives in fair value hedging relationships and the related hedged items on the consolidated statements of operations. All gains or losses on derivatives were included in the assessment of hedge effectiveness. Amount of gain Amount of gain Derivatives in fair value Hedged items in fair value 2016 2015 2014 2016 2015 2014 (in millions) (in millions) Interest rate contracts $ $ $ Fixed maturities, available-for-sale $ ) $ ) $ ) Interest rate contracts ) Investment contracts ) ) Foreign exchange contracts — Fixed maturities, available-for-sale — ) ) Foreign exchange contracts — — Investment contracts — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ Total $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The gain (loss) on both derivatives and hedged items in fair value relationships is reported in net realized capital gains (losses) on the consolidated statements of operations. The net amount represents the ineffective portion of our fair value hedges. The following table shows the periodic settlements on interest rate contracts and foreign exchange contracts in fair value hedging relationships. Amount of gain (loss) Hedged Item 2016 2015 2014 (in millions) Fixed maturities, available-for-sale (1) $ ) $ ) $ ) Investment contracts (2) (1) Reported in net investment income on the consolidated statements of operations. (2) Reported in benefits, claims and settlement expenses on the consolidated statements of operations. Cash Flow Hedges We utilize floating-to-fixed rate interest rate swaps to eliminate the variability in cash flows of recognized financial assets and liabilities and forecasted transactions. We enter into currency exchange swap agreements to convert both principal and interest payments of certain foreign denominated assets and liabilities into U.S. dollar denominated fixed-rate instruments to eliminate the exposure to future currency volatility on those items. The net interest effect of interest rate swap and currency swap transactions for derivatives in cash flow hedges is recorded as an adjustment to income or expense of the underlying hedged item in our consolidated statements of operations. The maximum length of time we are hedging our exposure to the variability in future cash flows for forecasted transactions, excluding those related to the payments of variable interest on existing financial assets and liabilities, is 3.5 years. As of December 31, 2016, we had $16.2 million of net gains reported in AOCI on the consolidated statements of financial position related to active hedges of forecasted transactions. If a hedged forecasted transaction is no longer probable of occurring, cash flow hedge accounting is discontinued. If it is probable that the hedged forecasted transaction will not occur, the deferred gain or loss is immediately reclassified from AOCI into net income. During 2016 and 2015, we did not have any reclassifications from AOCI into net realized capital gains (losses) as a result of the determination that hedged cash flows were probable of not occurring. The following table shows the effect of derivatives in cash flow hedging relationships on the consolidated statements of operations and consolidated statements of financial position. All gains or losses on derivatives were included in the assessment of hedge effectiveness. Amount of gain Amount of gain Location of gain (loss) Derivatives in cash flow Related hedged item 2016 2015 2014 2016 2015 2014 (in millions) (in millions) Interest rate contracts Fixed maturities, available-for-sale $ ) $ $ Net investment income $ $ $ Net realized capital gains — — Interest rate contracts Investment contracts Benefits, claims and settlement expenses — — — Interest rate contracts Debt — — — Operating expense ) ) ) Foreign exchange contracts Fixed maturities, available-for-sale Net realized capital gains (losses) ) Foreign exchange contracts Investment contracts Benefits, claims and settlement expenses — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ $ Total $ $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table shows the periodic settlements on interest rate contracts and foreign exchange contracts in cash flow hedging relationships. Amount of gain (loss) Hedged item 2016 2015 2014 (in millions) Fixed maturities, available-for-sale (1) $ $ $ Investment contracts (2) ) ) ) (1) Reported in net investment income on the consolidated statements of operations. (2) Reported in benefits, claims and settlement expenses on the consolidated statements of operations. The ineffective portion of our cash flow hedges is reported in net realized capital gains (losses) on the consolidated statements of operations. The net gain resulting from the ineffective portion of foreign currency contracts in cash flow hedging relationships was $0.3 million, $0.0 million and $0.0 million for the years ended December 31, 2016, 2015 and 2014, respectively. We expect to reclassify net gains of $3.7 million from AOCI into net income in the next 12 months, which includes both net deferred gains on discontinued hedges and net losses on periodic settlements of active hedges. Actual amounts may vary from this amount as a result of market conditions. Net Investment Hedges We may take measures to hedge our net equity investments in our foreign operations from currency risk. This is accomplished with the use of currency forwards. Gains and losses associated with net investment hedges are recorded in AOCI and will be released into earnings if our investment in the foreign operation is sold or substantially liquidated. The amount of gain recognized in AOCI on derivatives was $0.0 million, $1.7 million and $0.0 million for the years ended December 31, 2016, 2015 and 2014, respectively. We did not have any ineffectiveness and did not reclassify any gains or losses from AOCI into net income related to our net investment hedges for the years ended December 31, 2016, 2015 and 2014. Derivatives Not Designated as Hedging Instruments Our use of futures, certain swaptions and swaps, collars, options and forwards are effective from an economic standpoint, but they have not been designated as hedges for financial reporting purposes. As such, periodic changes in the market value of these instruments, which includes mark-to-market gains and losses as well as periodic and final settlements, primarily flow directly into net realized capital gains (losses) on the consolidated statements of operations. The following table shows the effect of derivatives not designated as hedging instruments, including fair value changes of embedded derivatives that have been bifurcated from the host contract, on the consolidated statements of operations. Amount of gain (loss) Derivatives not designated as hedging instruments 2016 2015 2014 (in millions) Interest rate contracts $ $ $ Foreign exchange contracts ) ) Equity contracts ) ) Credit contracts ) Other contracts ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Closed Block

Closed Block	12 Months Ended
	Dec. 31, 2016
Closed Block
Closed Block	6. Closed Block In connection with the 1998 MIHC formation, Principal Life formed a Closed Block to provide reasonable assurance to policyholders included therein that, after the formation of the MIHC, assets would be available to maintain dividends in aggregate in accordance with the 1997 policy dividend scales, if the experience underlying such scales continued. Assets of Principal Life were allocated to the Closed Block in an amount that produces cash flows which, together with anticipated revenue from policies and contracts included in the Closed Block, were expected to be sufficient to support the Closed Block policies. This includes, but is not limited to, provisions for payment of claims, certain expenses, charges and taxes, and to provide for continuation of policy and contract dividends in aggregate in accordance with the 1997 dividend scales, if the experience underlying such scales continues, and to allow for appropriate adjustments in such scales, if such experience changes. Due to adjustable life policies being included in the Closed Block, the Closed Block is charged with amounts necessary to properly fund for certain adjustments, such as face amount and premium increases, that are made to these policies after the Closed Block inception date. These amounts are referred to as Funding Adjustment Charges and are treated as capital transfers from the Closed Block. Assets allocated to the Closed Block inure solely to the benefit of the holders of policies included in the Closed Block. Closed Block assets and liabilities are carried on the same basis as other similar assets and liabilities. Principal Life will continue to pay guaranteed benefits under all policies, including the policies within the Closed Block, in accordance with their terms. If the assets allocated to the Closed Block, the investment cash flows from those assets and the revenues from the policies included in the Closed Block, including investment income thereon, prove to be insufficient to pay the benefits guaranteed under the policies included in the Closed Block, Principal Life will be required to make such payments from its general funds. No additional policies were added to the Closed Block, nor was the Closed Block affected in any other way, as a result of the demutualization. A policyholder dividend obligation ("PDO") is required to be established for earnings in the Closed Block that are not available to stockholders. A model of the Closed Block was established to produce the pattern of expected earnings in the Closed Block, adjusted to eliminate the impact of related amounts in AOCI. If actual cumulative earnings of the Closed Block are greater than the expected cumulative earnings of the Closed Block, only the expected cumulative earnings will be recognized in income with the excess recorded as a PDO. This PDO represents undistributed accumulated earnings that will be paid to Closed Block policyholders as dividends unless offset by future performance of the Closed Block that is less favorable than originally expected. If actual cumulative performance is less favorable than expected, only actual earnings will be recognized in income. As of December 31, 2016, cumulative actual earnings were greater than cumulative expected earnings. Therefore, we established an additional $8.2 million liability, which was recorded within policyholder dividends obligation. As of December 31, 2015, cumulative actual earnings were less than cumulative expected earnings. However, cumulative net unrealized gains were greater than expected, resulting in the recognition of a PDO of $117.9 million and $88.7 million as of December 31, 2016 and 2015, respectively. Closed Block liabilities and assets designated to the Closed Block were as follows: December 31, 2016 December 31, 2015 (in millions) Closed Block liabilities Future policy benefits and claims $ $ Other policyholder funds Policyholder dividends payable Policyholder dividends obligation Other liabilities ​ ​ ​ ​ ​ ​ ​ ​ Total Closed Block liabilities Assets designated to the Closed Block Fixed maturities, available-for-sale Fixed maturities, trading Equity securities, available-for-sale Mortgage loans Policy loans Other investments ​ ​ ​ ​ ​ ​ ​ ​ Total investments Cash and cash equivalents Accrued investment income Premiums due and other receivables Deferred tax asset Other assets — ​ ​ ​ ​ ​ ​ ​ ​ Total assets designated to the Closed Block ​ ​ ​ ​ ​ ​ ​ ​ Excess of Closed Block liabilities over assets designated to the Closed Block Amounts included in accumulated other comprehensive income ​ ​ ​ ​ ​ ​ ​ ​ Maximum future earnings to be recognized from Closed Block assets and liabilities $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues and expenses were as follows: For the year ended 2016 2015 2014 (in millions) Revenues Premiums and other considerations $ $ $ Net investment income Net realized capital losses ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Benefits, claims and settlement expenses Dividends to policyholders Operating expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues, net of Closed Block expenses, before income taxes Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues, net of Closed Block expenses and income taxes Funding adjustment charges ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues, net of Closed Block expenses, income taxes and funding adjustment charges $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The change in maximum future earnings of the Closed Block was as follows: For the year ended 2016 2015 2014 (in millions) Beginning of year $ $ $ End of year ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in maximum future earnings $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Principal Life charges the Closed Block with federal income taxes, payroll taxes, state and local premium taxes and other state or local taxes, licenses and fees as provided in the plan of reorganization.

Deferred Acquisition Costs

Deferred Acquisition Costs	12 Months Ended
	Dec. 31, 2016
Deferred Acquisition Costs
Deferred Acquisition Costs	7. Deferred Acquisition Costs Acquisition costs deferred and amortized were as follows: For the year ended 2016 2015 2014 (in millions) Balance at beginning of year $ $ $ Costs deferred during the year Amortized to expense during the year (1) ) ) ) Adjustment related to unrealized (gains) losses on available-for-sale securities and derivative instruments ) ) Other — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes adjustments for revisions to estimated gross profits.

Insurance Liabilities

Insurance Liabilities	12 Months Ended
	Dec. 31, 2016
Insurance Liabilities
Insurance Liabilities	8. Insurance Liabilities Contractholder Funds Major components of contractholder funds in the consolidated statements of financial position were as follows: December 31, 2016 2015 (in millions) Liabilities for investment contracts: Liabilities for individual annuities $ $ GICs Funding agreements Other investment contracts ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities for investment contracts Universal life and other reserves ​ ​ ​ ​ ​ ​ ​ ​ Total contractholder funds $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Our GICs and funding agreements contain provisions limiting or prohibiting early surrenders, which typically include penalties for early surrenders, minimum notice requirements or, in the case of funding agreements with survivor options, minimum pre-death holding periods and specific maximum amounts. Funding agreements include those issued directly to nonqualified institutional investors, as well as under five separate programs where the funding agreements have been issued directly or indirectly to unconsolidated special purpose entities. Claims for principal and interest under funding agreements are afforded equal priority to claims of life insurance and annuity policyholders under insolvency provisions of Iowa Insurance Laws. Principal Life was authorized to issue up to $4.0 billion of funding agreements under a program established in 1998 to support the prospective issuance of medium term notes by an unaffiliated entity in non-U.S. markets. As of December 31, 2016 and 2015, $106.7 million and $107.5 million, respectively, of liabilities were outstanding with respect to the issuance outstanding under this program. Principal Life was also authorized to issue up to Euro 4.0 billion (approximately USD$5.3 billion) of funding agreements under a program established in 2006 to support the prospective issuance of medium term notes by an unaffiliated entity in non-U.S. markets. The unaffiliated entity is an unconsolidated special purpose vehicle. As of December 31, 2016 and 2015, $702.0 million and $1,021.0 million, respectively, of liabilities were outstanding with respect to issuances outstanding under this program. Principal Life does not anticipate any new issuance activity under either of these programs due to the existence of the program established in 2011 described below. In addition, Principal Life was authorized to issue up to $7.0 billion of funding agreements under a program established in 2001 to support the prospective issuance of medium term notes by an unaffiliated entity in both domestic and international markets. The unaffiliated entity is an unconsolidated special purpose entity. As of December 31, 2016 and 2015, $201.5 million and $201.4 million, respectively, of liabilities were being held with respect to issuances outstanding under this program. Principal Life does not anticipate any new issuance activity under this program, given our December 2005 termination of the dealership agreement for this program and the availability of the program established in 2011 described below. Additionally, Principal Life was authorized to issue up to $9.0 billion of funding agreements under a program that was originally established in March 2004 to support the prospective issuance of medium term notes by unaffiliated entities in both domestic and international markets. Under this program, both the notes and the supporting funding agreements were registered with the United States Securities and Exchange Commission ("SEC"). As of December 31, 2016 and 2015, $119.8 million and $246.0 million, respectively, of liabilities were being held with respect to issuances outstanding under this program. In contrast with direct funding agreements, GIC issuances and the other three funding agreement-backed medium term note programs described above, Principal Life's payment obligations on each funding agreement issued under this SEC-registered program are guaranteed by PFG. Principal Life does not anticipate any new issuance activity under this program due to the existence of the program established in 2011 described below. Principal Life was authorized to issue up to $5.0 billion of funding agreements under a program that was originally established in 2011 to support the prospective issuance of medium term notes by an unaffiliated entity in both domestic and international markets. The unaffiliated entity is an unconsolidated special purpose entity. In June 2015, this program was amended to authorize issuance of up to an additional $4.0 billion in recognition of the use of nearly all $5.0 billion of existing issuance authorization. As of December 31, 2016 and 2015, $4,389.4 million and $3,537.0 million, respectively, of liabilities were being held with respect to issuances outstanding under this program. Similar to the SEC-registered program, Principal Life's payment obligations on each funding agreement issued under this program are guaranteed by PFG. The program established in 2011 is not registered with the SEC. Liability for Unpaid Claims The liability for unpaid claims is reported in future policy benefits and claims within our consolidated statements of financial position. Activity associated with unpaid claims was as follows: December 31, 2016 2015 2014 (in millions) Balance at beginning of year $ $ $ Less: reinsurance recoverable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net balance at beginning of year Incurred: Current year Prior years ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total incurred Payments: Current year Prior years ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total payments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net balance at end of year Plus: reinsurance recoverable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts not included in the rollforward above: Claim adjustment expense liabilities $ $ $ Incurred liability adjustments relating to prior years, which affected current operations during 2016, 2015 and 2014, resulted in part from developed claims for prior years being different than were anticipated when the liabilities for unpaid claims were originally estimated. These trends have been considered in establishing the current year liability for unpaid claims. Short-Duration Contracts Claims Development The following tables present undiscounted information about claims development by incurral year, including separate information about incurred claims and paid claims net of reinsurance for the periods indicated. The tables also include information on incurred but not reported claims and the cumulative number of reported claims. The tables present information for the number of years for which claims incurred typically remain outstanding, but do not exceed ten years. The data is disaggregated into groupings of claims with similar characteristics, such as duration of the claim payment period and average claim amount, and with consideration to the overall size of the groupings. Outstanding liabilities equal total net incurred claims less total net paid claims plus outstanding liabilities for net unpaid claims of prior years. LTD and Group Life Waiver Claims Net incurred claims (1) Incurred Cumulative December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2016 2016 ($ in millions) Incurral year 2007 $ $ $ $ $ $ $ $ $ $ $ 2008 2009 2010 2011 2012 2013 2014 2015 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net incurred claims $ Net cumulative paid claims (1) December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 (in millions) Incurral year 2007 $ $ $ $ $ $ $ $ $ $ 2008 2009 2010 2011 2012 2013 2014 2015 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net paid claims All outstanding liabilities for unpaid claims prior to 2007 net of reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total outstanding liabilities for unpaid claims net of reinsurance $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) 2007 - 2015 unaudited. Dental, Vision and STD Claims Net incurred Incurred Cumulative December 31, 2015 2016 2016 2016 ($ in millions) Incurral year 2015 $ $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net incurred claims $ Net cumulative December 31, 2015 2016 (in millions) Incurral year 2015 $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net paid claims All outstanding liabilities for unpaid claims prior to 2015 net of reinsurance — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total outstanding liabilities for unpaid claims net of reinsurance $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) 2015 unaudited. Group Life Claims Net incurred Incurred Cumulative December 31, 2015 2016 2016 2016 ($ in millions) Incurral year 2015 $ $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net incurred claims $ Net cumulative December 31, 2015 2016 (in millions) Incurral year 2015 $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net paid claims All outstanding liabilities for unpaid claims prior to 2015 net of reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total outstanding liabilities for unpaid claims net of reinsurance $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) 2015 unaudited. Reconciliation of Unpaid Claims to Liability for Unpaid Claims Our reconciliation of net outstanding liabilities for unpaid claims of short-duration contracts to the liability for unpaid claims follows: December 31, 2016 LTD and Dental, Group Consolidated (in millions) Net outstanding liabilities for unpaid claims $ $ $ $ Reconciling items: Reinsurance recoverable on unpaid claims — Impact of discounting ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liability for unpaid claims — short-duration contracts $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Insurance contracts other than short-duration ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liability for unpaid claims $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Claim Duration and Payout Our historical average percentage of claims paid in each year from incurral was as follows: December 31, 2016 Year LTD and Dental, Group 1 % % % 2 3 4 5 6 7 8 9 10 Discounting The following table provides the carrying amount of liabilities reported at present value for short-duration contract unpaid claims. We use a range of discount rates to derive the present value of the unpaid claims. The ranges of discount rates as well as the aggregate amount of discount deducted to derive the liabilities for unpaid claims and interest accretion recognized are also disclosed. Interest accretion is included in benefits, claims and settlement expenses within our consolidated statements of operations. LTD and Group Dental, Vision Group Life ($ in millions) Carrying amount of liabilities for unpaid claims December 31, 2016 $ $ $ December 31, 2015 Range of discount rates December 31, 2016 3.3 - 7.0 % — - — % — - — % December 31, 2015 3.3 - 7.0 — - — — - — Aggregate amount of discount December 31, 2016 $ $ — $ — December 31, 2015 — — Interest accretion For the year ended: December 31, 2016 $ $ — $ — December 31, 2015 — — December 31, 2014 — —

Debt

Debt	12 Months Ended
	Dec. 31, 2016
Debt
Debt	9. Debt Short-Term Debt The components of short-term debt were as follows: December 31, 2016 2015 (in millions) Line of credit $ $ Other recourse short-term debt — ​ ​ ​ ​ ​ ​ ​ ​ Total short-term debt $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of both December 31, 2016 and 2015, we had short-term credit facilities with various financial institutions in an aggregate amount of $1,005.0 million. As of December 31, 2016 and 2015, we had $51.4 million and $181.1 million, respectively, of outstanding borrowings, with no assets pledged as support. Our credit facilities include a $400.0 million 5-year facility that matures in March 2021, with Principal Financial Services, Inc., Principal Life and us as co-borrowers, a $300.0 million 364-day facility with Principal Life as borrower that matures in March 2017, and a $200.0 million 5-year facility with Principal Financial Services, Inc., Principal Life, Principal Financial Services V (UK) LTD and us as the co-borrowers that matures in March 2021. These facilities may be used for general corporate purposes, including commercial paper back-stop. In addition to the revolving credit facilities, Principal International Chile has the capacity to access up to $60.0 million in unsecured lines of credit offered by Chilean financial institutions and Principal Life has a $45.0 million unsecured line of credit. Our commercial paper programs require 100% back-stop support, of which we had no outstanding balances as of December 31, 2016 and 2015. The weighted-average interest rate on short-term borrowings as of December 31, 2016 and 2015, was 4.4% and 4.2%, respectively. Long-Term Debt The components of long-term debt were as follows: December 31, 2016 Principal Net unamortized Carrying (in millions) 3.3% notes payable, due 2022 $ $ ) $ 3.125% notes payable, due 2023 ) 3.4% notes payable, due 2025 ) 3.1% notes payable, due 2026 ) 6.05% notes payable, due 2036 ) 4.625% notes payable, due 2042 ) 4.35% notes payable, due 2043 ) 4.3% notes payable, due 2046 ) 4.7% notes payable, due 2055 ) Non-recourse mortgages and notes payable (1) — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total long-term debt $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Principal Net unamortized Carrying (in millions) 1.85% notes payable, due 2017 $ $ ) $ 8.875% notes payable, due 2019 ) 3.3% notes payable, due 2022 ) 3.125% notes payable, due 2023 ) 3.4% notes payable, due 2025 ) 6.05% notes payable, due 2036 ) 4.625% notes payable, due 2042 ) 4.35% notes payable, due 2043 ) 4.7% notes payable, due 2055 ) Non-recourse mortgages and notes payable (1) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total long-term debt $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes external debt issuance costs incurred for long-term affiliated debt issued in a foreign jurisdiction. Net discount, premium and issuance costs associated with issuing these notes are amortized to expense over the respective terms using the interest method. On November 10, 2016, we issued $650.0 million of senior notes. We issued a $350.0 million series of notes that bear interest at 3.1% and will mature in 2026 and a $300.0 million series of notes that bear interest at 4.3% and will mature in 2046. Interest on the notes is payable semi-annually on May 15 and November 15 each year, beginning on May 15, 2017. The proceeds from these notes were used to redeem our notes payable due in 2017 and 2019. We incurred a one-time cost to extinguish this debt before the scheduled maturity date. On May 7, 2015, we issued $400.0 million of senior notes. The notes bear interest at 3.4% and will mature in 2025. Interest on the notes is payable semi-annually on May 15 and November 15 each year, beginning on November 15, 2015. In addition, on May 7, 2015, we issued $400.0 million of junior subordinated notes, which are subordinated to all our senior debt. The notes are callable in 2020 and have a maturity date in 2055. The notes initially bear a fixed rate of interest at 4.7% and convert to a floating rate at the date the notes become callable. Interest on the notes is payable semi-annually on May 15 and November 15 each year. After the call date the notes will bear interest at 3-month LIBOR plus 3.044%, reset quarterly and payable in arrears in February, May, August and November each year. We have the right to defer interest payments on the junior subordinated notes for up to 5 years without resulting in a default, during which time interest will be compounded. The proceeds from these notes were used to redeem our series A and series B preferred stock with the remainder available for general corporate purposes. On November 16, 2012, we issued $900.0 million of senior notes. We issued a $300.0 million series of notes that bore interest at 1.85% and were to mature in 2017. These notes were repaid following our November 2016 debt issuance. We issued a $300.0 million series of notes that bear interest at 3.125% and will mature in 2023 and a $300.0 million series of notes that bear interest at 4.35% and will mature in 2043. Interest on the notes is payable semi-annually on May 15 and November 15 each year, beginning on May 15, 2013. The proceeds were used to fund our acquisition of Cuprum. On September 5, 2012, we issued $600.0 million of senior notes. We issued a $300.0 million series of notes that bear interest at 3.3% and will mature in 2022 and a $300.0 million series of notes that bear interest at 4.625% and will mature in 2042. Interest on the notes is payable semi-annually on March 15 and September 15 each year, beginning on March 15, 2013. The proceeds were used for the repayment of the $400.0 million aggregate principal amount of notes due in 2014 and to partially fund our acquisition of Cuprum. On May 18, 2009, we issued $750.0 million of senior notes. We issued a $400.0 million series of notes that bore interest at 7.875% and were to mature on May 15, 2014. These notes were repaid following our November 2012 debt issuance. We issued a $350.0 million series of notes that bore interest at 8.875% and were to mature on May 15, 2019. These notes were repaid following our November 2016 debt issuance. Interest on the notes was payable semi-annually on May 15 and November 15 each year, beginning on November 15, 2009. The proceeds were primarily used to refinance $440.9 million of notes that matured on August 15, 2009, with the remaining proceeds being used for general corporate purposes. On October 16 and December 5, 2006, we issued $500.0 million and $100.0 million, respectively, of senior notes. The notes bear interest at a rate of 6.05% per year. Interest on the notes is payable semi-annually on April 15 and October 15 each year and began on April 15, 2007. The notes will mature on October 15, 2036. A portion of the proceeds were used to fund the 2006 acquisition of WM Advisors, Inc., with the remaining proceeds being used for general corporate purposes. A tender offer in the fourth quarter of 2016 resulted in redemption of $94.4 million of the senior notes. We incurred a one-time cost to extinguish this debt before the scheduled maturity date. The non-recourse mortgages and notes payable are primarily financings for real estate developments. Outstanding principal balances as of December 31, 2016, were $0.0 million due to outstanding debt maturing in 2016. Outstanding principal balances as of December 31, 2015, ranged from $1.8 million to $41.1 million per development with interest rates being variable. Outstanding debt is secured by the underlying real estate properties, which were reported as real estate on our consolidated statements of financial position with a carrying value of $79.5 million as of December 31, 2015. As of December 31, 2016, future annual maturities of long-term debt were as follows (in millions): Year ending December 31: 2017 $ — 2018 — 2019 — 2020 — 2021 — Thereafter ​ ​ ​ ​ ​ Total future maturities of long-term debt $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Taxes
Income Taxes	10. Income Taxes Income Tax Expense Our income tax expense was as follows: For the year ended 2016 2015 2014 (in millions) Current income taxes: U.S. federal $ $ $ State ) Foreign Tax benefit of operating loss carryforward ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total current income taxes Deferred income taxes (benefits): U.S. federal State ) ) ) Foreign ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total deferred income taxes (benefits) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income taxes $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective Income Tax Rate Our provision for income taxes may not have the customary relationship of taxes to income. A reconciliation between the U.S. corporate income tax rate and the effective income tax rate was as follows: For the year ended 2016 2015 2014 U.S. corporate income tax rate % % % Dividends received deduction ) ) ) Impact of equity method presentation ) ) ) Tax credits ) ) ) Interest exclusion from taxable income ) ) ) Foreign country permanent tax adjustments ) — — Impact of noncontrolling interest presentation ) — — Merger of Chilean legal entities — ) — Foreign tax rate differential — — ) Impact of court ruling on some uncertain tax positions — — Impact of enactment of tax legislation — — Other ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective income tax rate % % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Our income before income taxes was as follows: For the year ended 2016 2015 2014 (in millions) Domestic $ $ $ Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income before income taxes $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized Tax Benefits Our changes in unrecognized tax benefits were as follows: For the year 2016 2015 (in millions) Balance at beginning of period $ $ Additions based on tax positions related to the current year Additions for tax positions of prior years Reductions for tax positions related to the current year ) ) Reductions for tax positions of prior years ) ) ​ ​ ​ ​ ​ ​ ​ ​ Balance at end of period (1) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Of this amount, $81.0 million, if recognized, would reduce the 2016 effective income tax rate. We recognize interest and penalties related to uncertain tax positions in operating expenses within the consolidated statements of operations. As of December 31, 2016 and 2015, we had recognized $142.4 million and $137.9 million of accumulated pre-tax interest and penalties related to unrecognized tax benefits, respectively. Net Deferred Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Our significant components of net deferred income taxes were as follows: December 31, 2016 2015 (in millions) Deferred income tax assets: Insurance liabilities $ $ Investments, including derivatives Net operating and capital loss carryforwards Tax credit carryforwards Employee benefits Foreign currency translation Other deferred income tax assets ​ ​ ​ ​ ​ ​ ​ ​ Gross deferred income tax assets Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred income tax assets Deferred income tax liabilities: Deferred acquisition costs ) ) Investments, including derivatives ) ) Net unrealized gains on available-for-sale securities ) ) Real estate ) ) Intangible assets ) ) Other deferred income tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred income tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total net deferred income tax liabilities $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Our net deferred income taxes by jurisdiction were as follows: December 31, 2016 2015 (in millions) Deferred income tax assets: State $ $ Foreign ​ ​ ​ ​ ​ ​ ​ ​ Net deferred income tax assets Deferred income tax liabilities: U.S. federal ) ) Foreign ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred income tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total net deferred income tax liabilities $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In management's judgment, total deferred income tax assets are more likely than not to be realized. Included in the deferred income tax asset are tax carryforwards available to offset future taxable income or income taxes. As of December 31, 2016 and 2015, we had tax credit carryforwards for U.S. federal income tax purposes of $275.7 million and $227.4 million, respectively. Alternative minimum, foreign and general business tax credit carryovers were generated during the period we utilized net operating losses, primarily attributable to our captive reinsurance companies that joined our consolidated U.S. federal income tax return beginning in 2012 and 2013. Some of these tax credit carryforwards will expire in 2023 while others never expire. As of December 31, 2016, all accumulated U.S. federal tax credit carryforwards are anticipated to be utilized before expiration; therefore, no valuation allowance has been provided for the related deferred income tax assets. As of December 31, 2016 and 2015, domestic state net operating and capital loss carryforwards were $587.7 million and $387.7 million, respectively, and expired or will expire between 2021 and 2035. As of December 31, 2016 and 2015, foreign net operating loss carryforwards were $151.6 million and $197.1 million, respectively, with some expiring in 2017 while others never expire. We maintain valuation allowances by jurisdiction against the deferred income tax assets related to certain of these carryforwards and other items, as utilization of these income tax benefits fail the more likely than not criteria in certain jurisdictions. As of December 31, 2016 and 2015, valuation allowances of $7.3 million and $11.9 million, respectively, had been recorded against the income tax benefits associated primarily with foreign net operating loss carryforwards. Adjustments to the valuation allowance will be made if there is a change in management's assessment of the amount of the deferred income tax assets that are more likely than not to be realized. Tax legislation increasing the Brazilian tax rate was enacted in September 2015. The three-year rate increase did not have a material impact on our consolidated results. Tax legislation transitioning an increase in the Chilean tax rate over five years was enacted in September 2014. Our net deferred tax liabilities increased $58.1 million in the third quarter of 2014 as a result of the legislation in Chile. Deferred tax liabilities are recognized for taxes payable on the unremitted earnings from foreign operations of our subsidiaries, except where it is our intention to indefinitely reinvest a portion or all of these undistributed earnings. As of December 31, 2016 and 2015, U.S. federal and state deferred income taxes were not provided on approximately $1,088.4 million and $1,004.6 million, respectively, of such accumulated but undistributed earnings from operations of foreign subsidiaries. We currently do not intend to repatriate these unremitted earnings because we have several liquidity options to fund our domestic operations and obligations. These options include investing and financing activities, such as issuing debt, as well as cash-flow and dividends from domestic operations. It is not practicable to determine the amount of the unrecognized deferred tax liability that would arise if foreign earnings were remitted due to the complexity of our international holding company structure, the availability of foreign tax credits, the rules governing the utilization of foreign tax credits, and the interplay between utilization of such foreign tax credits and other significant tax attributes. As of December 31, 2016, deferred taxes were also not provided on the approximately $106.2 million of excess book carrying value over tax basis with respect to the original investment in our foreign subsidiaries. A tax liability will be recognized when we no longer plan to indefinitely reinvest a portion or all of these earnings or when we plan to sell a portion or all of our ownership interest. Other Tax Information Income tax returns are filed in the U.S. federal jurisdiction as well as various states and foreign jurisdictions where we and one or more of our subsidiaries conduct business. Although determined by jurisdiction, with few exceptions our tax uncertainties relate primarily to the U.S. federal jurisdiction. The Internal Revenue Service ("IRS") has completed examination of our consolidated U.S. federal income tax returns for years prior to 2009. We are contesting certain issues and have filed suit in the Court of Federal Claims, requesting refunds for the years 1995-2003. We believe there is a reasonable possibility this litigation can be resolved within the next twelve months. As of December 31, 2016 and 2015, we had $242.9 million and $229.9 million, respectively, of current income tax receivables associated with outstanding audit issues reported as other assets in our consolidated statements of financial position. We filed claims for refund for tax years 2006 through 2008 in 2015 and tax year 2012 in 2016. The IRS commenced audit of our U.S. federal income tax return for 2009 in the fourth quarter of 2011, 2010 in the first quarter of 2012, 2011 in the first quarter of 2013, and 2012 in the third quarter of 2015. We do not expect the results of these audits or developments in other tax areas for all open tax years to significantly change the possible increase in the amount of unrecognized tax benefits, but the outcome of tax reviews is uncertain and unforeseen results can occur. The U.S. Court of Federal Claims denied cross-motions for partial summary judgment on February 4, 2015, and ordered a trial on the previously taxed income issue in the case of Principal Life Insurance Company and Subsidiaries v. the United States. Previously, in the same case, on May 9, 2014, the court ruled against Principal Life's tax treatment of transactions involving the purchase and sale of principal-only certificates. These recent events caused the re-evaluation of all our pending uncertain tax positions, which resulted in a $30.3 million reduction in net income in the first quarter of 2015 and a $47.5 million reduction in net income in the second quarter of 2014. We believe we have adequate defenses against, or sufficient provisions for, the contested issues, but final resolution could take several years while legal remedies are pursued. Consequently, we do not expect the ultimate resolution of issues from tax years 1995-2003 or those that might arise in tax years subsequent to 2003 to have a material impact on our net income. We do not believe there is a reasonable possibility the total amount of uncertain tax benefits will significantly increase or decrease in the next twelve months.

Employee and Agent Benefits

Employee and Agent Benefits	12 Months Ended
	Dec. 31, 2016
Employee and Agent Benefits
Employee and Agent Benefits	11. Employee and Agent Benefits We have defined benefit pension plans covering substantially all of our U.S. employees and certain agents. Some of these plans provide supplemental pension benefits to employees and agents with salaries and/or pension benefits in excess of the qualified plan limits imposed by federal tax law. The employees and agents are generally first eligible for the pension plans when they reach age 21. For plan participants employed prior to January 1, 2002, the pension benefits are based on the greater of a final average pay benefit or a cash balance benefit. The final average pay benefit is based on the years of service and generally the employee's or agent's average annual compensation during the last five years of employment. Partial benefit accrual of final average pay benefits is recognized from first eligibility until retirement based on attained service divided by potential service to age 65 with a minimum of 35 years of potential service. The cash balance portion of the plan started on January 1, 2002. An employee's account is credited with an amount based on the employee's salary, age and service. These credits accrue with interest. For plan participants hired on and after January 1, 2002, only the cash balance plan applies. Our policy is to fund the cost of providing pension benefits in the years that the employees and agents are providing service to us. Our funding policy for the qualified defined benefit plan is to contribute an amount annually at least equal to the minimum annual contribution required under the Employee Retirement Income Security Act ("ERISA"), and, generally, not greater than the maximum amount that can be deducted for federal income tax purposes. Our funding policy for the nonqualified benefit plan is to fund the plan in the years the employees are providing service, taking into account the funded status of the trust. While we designate assets to cover the computed liability of the nonqualified plan, the assets are not included as part of the asset balances presented in this footnote as they do not qualify as plan assets in accordance with U.S. GAAP. We also provide certain health care, life insurance and long-term care benefits for retired employees. Subsidized retiree health benefits are provided for employees hired prior to January 1, 2002 and who retire prior to January 1, 2020. Employees hired on or after January 1, 2002, or hired prior to January 1, 2002, and who retire on or after January 1, 2020, have access to retiree health benefits but it is intended that they pay for the full cost of the coverage. The health care plans are contributory with participants' contributions adjusted annually. The contributions are based on the number of years of service and age at retirement for those hired prior to January 1, 2002, and who retired prior to January 1, 2011. For employees hired prior to January 1, 2002, and who retire on or after January 1, 2011, but prior to January 1, 2020, the contributions are 60% of the expected cost. As part of the substantive plan, the retiree health contributions are assumed to be adjusted in the future as claim levels change. The life insurance plans are contributory for a small group of previously grandfathered participants that have elected supplemental coverage and dependent coverage. The retiree group term life coverage is not subsidized for those who retire on or after January 1, 2020. Covered employees are first eligible for the health and life postretirement benefits when they reach age 57 and have completed ten years of service with us. Retiree long-term care benefits are provided for employees whose retirement was effective prior to July 1, 2000. Our policy is to fund the cost of providing retiree benefits in the years the employees are providing service, taking into account the funded status of the trust. Obligations and Funded Status The plans' combined funded status, reconciled to amounts recognized in the consolidated statements of financial position, was as follows: Pension benefits Other December 31, December 31, 2016 2015 2016 2015 (in millions) Change in benefit obligation Benefit obligation at beginning of year $ ) $ ) $ ) $ ) Service cost ) ) ) ) Interest cost ) ) ) ) Actuarial gain (loss) ) ) Participant contribution — — ) ) Benefits paid Plan amendments — — Other — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at end of year $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in plan assets Fair value of plan assets at beginning of year $ $ $ $ Actual return on plan assets ) ) Employer contribution Participant contributions — — Benefits paid ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount recognized in statement of financial position Other assets $ — $ — $ $ Other liabilities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ ) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount recognized in accumulated other comprehensive (income) loss Total net actuarial (gain) loss $ $ $ $ ) Prior service benefit ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax accumulated other comprehensive (income) loss $ $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The accumulated benefit obligation for all defined benefit pension plans was $2,821.1 million and $2,799.2 million as of December 31, 2016 and 2015, respectively. Employer contributions to the pension plans include contributions made directly to the qualified pension plan assets and contributions from corporate assets to pay nonqualified pension benefits. Benefits paid from the pension plans include both qualified and nonqualified plan benefits. Nonqualified pension plan assets are not included as part of the asset balances presented in this footnote. The nonqualified pension plan assets are held in Rabbi trusts for the benefit of all nonqualified plan participants. The assets held in a Rabbi trust are available to satisfy the claims of general creditors only in the event of bankruptcy. Therefore, these assets are fully consolidated in our consolidated statements of financial position and are not reflected in our funded status as they do not qualify as plan assets under U.S. GAAP. The market value of assets held in these trusts was $341.0 million and $330.8 million as of December 31, 2016 and 2015, respectively. Pension Plan Changes and Plan Gains/Losses On January 1, 2010, benefits under the Principal Pension Plan were frozen for certain participants. For the year ended December 31, 2016, the pension plans had an actuarial loss primarily due to assumption changes, including the decrease in the discount rate. For the year ended December 31, 2015, the pension plans had an actuarial gain primarily due to the increase in discount rate offset by less than expected investment returns. Other Postretirement Plan Changes and Plan Gains/Losses The Medicare Prescription Drug, Improvement and Modernization Act of 2003 (the "Medicare Modernization Act") provides a prescription drug benefit under Medicare ("Medicare Part D") as well as a federal subsidy to sponsors of retiree medical benefit plans. During each of the years ended December 31, 2016, 2015 and 2014, the Medicare subsidies we received and accrued for were $0.1 million, $0.7 million and $0.7 million, respectively. Effective October 31, 2016, subsidies were eliminated for pre-65 retiree medical, retiree dental, and retiree group term life coverage for employees and agents who retire on or after January 1, 2020. The amendment to the OPEB plan resulted in a remeasurement, which resulted in a change in discount rate. This plan amendment reduced our accumulated postretirement benefit obligation by $51.6 million. Effective January 1, 2016, post-65 medical coverage for employees who retired from January 1, 1992, to December 31, 2010, transitioned from a traditional medical plan to a stipend health reimbursement arrangement. This plan change reduced our accumulated postretirement benefit obligation by $15.5 million as of December 31, 2015. Offsetting this reduction is an adjustment in accumulated postretirement benefit obligation (recognized in fourth quarter 2015 expense) of $5.8 million related to dental plan benefits. For the year ended December 31, 2016, the other postretirement benefit plans had an actuarial gain primarily due to actual and projected medical claims costs being lower than previously expected offset by a decrease in the discount rate. For the year ended December 31, 2015, the other postretirement benefit plans had an actuarial loss primarily due to a greater than expected increase in claim costs and a longer trend rate for participants under age 65. Information for Pension Plans With an Accumulated Benefit Obligation in Excess of Plan Assets For 2016 and 2015, both the qualified and nonqualified plans had accumulated benefit obligations in excess of plan assets. As noted previously, the nonqualified plans have assets that are deposited in trusts that fail to meet the U.S. GAAP requirements to be included in plan assets; however, these assets are included in our consolidated statements of financial position. December 31, 2016 2015 (in millions) Projected benefit obligation $ $ Accumulated benefit obligation Fair value of plan assets Information for Other Postretirement Benefit Plans With an Accumulated Postretirement Benefit Obligation in Excess of Plan Assets December 31, 2016 2015 (in millions) Accumulated postretirement benefit obligation $ $ Fair value of plan assets Components of Net Periodic Benefit Cost Pension benefits Other postretirement For the year ended December 31, 2016 2015 2014 2016 2015 2014 (in millions) Service cost $ $ $ $ $ $ Interest cost Expected return on plan assets ) ) ) ) ) ) Amortization of prior service benefit ) ) ) ) ) ) Recognized net actuarial (gain) loss ) ) Plan amendments — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net periodic benefit cost (income) $ $ $ $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The pension plans' actuarial gains and losses are amortized using a straight-line amortization method over the average remaining service period of plan participants. For the qualified pension plan, gains and losses are amortized without use of the 10% allowable corridor. For the nonqualified pension plans and other postretirement benefit plans, the corridors allowed are used. Pension Other For the year ended December 31, 2016 2015 2016 2015 (in millions) Other changes recognized in accumulated other comprehensive (income) loss Net actuarial loss $ $ $ $ Amortization of gain (loss) ) ) ) Amortization of prior service benefit Plan amendments — — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in pre-tax accumulated other comprehensive (income) loss $ ) $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial (gain) loss and net prior service cost benefit have been recognized in AOCI. The estimated net actuarial (gain) loss and prior service cost (benefit) that will be amortized from AOCI into net periodic benefit cost for the pension benefits during the 2017 fiscal year are $68.0 million and $(2.3) million, respectively. The estimated net actuarial (gain) loss and prior service cost (benefit) for the postretirement benefits that will be amortized from AOCI into net periodic benefit cost during the 2017 fiscal year are $0.0 million and $(34.6) million, respectively. Assumptions Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section Pension benefits For the year ended 2016 2015 Discount rate % % Rate of compensation increase: Cash balance benefit % % Traditional benefit % % Other For the year ended 2016 2015 Discount rate % % Rate of compensation increase % % Weighted average assumptions used to determine net periodic benefit cost Pension benefits For the year ended 2016 2015 2014 Discount rate % % % Expected long-term return on plan assets % % % Rate of compensation increase: Cash balance benefit % % % Traditional benefit % % % Other For the year ended 2016 2015 2014 Discount rate (1) % % % Expected long-term return on plan assets % % % Rate of compensation increase % % % (1) The funded statuses of the affected plans were remeasured as of October 31, 2016, and a portion of the impact was reflected in the 2016 net periodic postretirement benefit cost. A discount rate of 4.15% was used until the remeasurement date at which time a discount rate of 3.35% was used. The assumed salary growth rates used to project benefits for the projected benefit obligation are age-based for home office employees. The rate labeled cash balance benefit (relative to employees accruing a cash balance) is the lifecount-weighted average rate of salary growth in the coming year only, as the impact of salary assumption for cash balance benefits are limited to the upcoming year service cost. The rate labeled traditional benefit (relative to employees still accruing a final average pay benefit) is the lifecount-weighted average (at each age) of the single annual growth rate at the age that is equivalent to applying the scale from that age to age 65. For the pension benefits, the discount rate is determined by projecting future benefit payments inherent in the projected benefit obligation and discounting those cash flows using a spot yield curve for high quality corporate bonds. The plans' expected benefit payments are discounted to determine a present value using the yield curve and the discount rate is the level rate that produces the same present value. The expected return on plan assets is the long-term rate we expect to be earned based on the plans' investment strategy. Historical and expected future returns of multiple asset classes were analyzed to develop a risk free rate of return and risk premiums for each asset class. The overall rate for each asset class was developed by combining a long-term inflation component, the risk free real rate of return and the associated risk premium. A weighted average rate was developed based on those overall rates and the target asset allocation of the plans. For other postretirement benefits, the discount rate is determined by projecting future benefit payments inherent in the accumulated postretirement benefit obligation, and discounting those cash flows using a spot yield curve for high quality corporate bonds. The plans' expected benefit payments are discounted to determine a present value using the yield curve and the discount rate is the level rate that produces the same present value. The 5.24% expected long-term return on plan assets for 2016 was based on the weighted average expected long-term asset returns for the medical, life and long-term care plans. The expected long-term rates for the medical under age 65, medical age 65 and over, life and long-term care plans were 5.20%, 5.10%, 5.70% and 4.25%, respectively. Assumed Health Care Cost Trend Rates December 31, 2016 2015 Health care cost trend rate assumed for next year under age 65 % % Health care cost trend rate assumed for next year age 65 and over % % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) % % Year that the rate reaches the ultimate trend rate (under age 65) Year that the rate reaches the ultimate trend rate (65 and older) Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. A one-percentage-point change in assumed health care cost trend rates would have the following effects: 1-percentage 1-percentage (in millions) Effect on total of service cost and interest cost components $ $ ) Effect on accumulated postretirement benefit obligation ) Pension Plan and Other Postretirement Benefit Plan Assets Fair value is defined as the price that would be received to sell an asset in an orderly transaction between market participants at the measurement date (an exit price). The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels. • Level 1 — Fair values are based on unadjusted quoted prices in active markets for identical assets. Our Level 1 assets include cash, fixed income investment funds, exchange traded equity securities and alternative mutual fund investments. • Level 2 — Fair values are based on inputs other than quoted prices within Level 1 that are observable for the asset, either directly or indirectly. Our Level 2 assets primarily include fixed income and equity investment funds and real estate investments. • Level 3 — Fair values are based on significant unobservable inputs for the asset. Our Level 3 assets include a Principal Life general account investment. Our pension plan assets consist of investments in separate accounts. Net asset value ("NAV") of the separate accounts is calculated in a manner consistent with U.S. GAAP for investment companies and is determinative of their fair value. Several of the separate accounts invest in publicly quoted mutual funds or actively managed stocks. The fair value of the underlying mutual funds or stock is used to determine the NAV of the separate account, which is not publicly quoted. Some of the separate accounts also invest in fixed income securities. The fair value of the underlying securities is based on quoted prices of similar assets and used to determine the NAV of the separate account. Some of the separate accounts invest in real estate properties. The fair value is based on discounted cash flow valuation models that utilize public real estate market data inputs such as transaction prices, market rent growth, vacancy levels, leasing absorption, market capitalization rates and discount rates. Our other postretirement benefit plan assets consist of cash, investments in fixed income security portfolios, investments in equity security portfolios, investments in alternative mutual fund portfolios and investment in a real estate mutual fund. Because of the nature of cash, its carrying amount approximates fair value. The fair value of fixed income investment funds, U.S. equity portfolios and international equity portfolios is based on quoted prices in active markets for identical assets. The fair value of the alternative mutual fund portfolios and the real estate mutual fund are based on quoted market prices, which represent NAV of shares held by the other postretirement benefit plan. The fair value of the Principal Life general account investment is the amount the plan would receive if withdrawing funds from this participating contract. The amount that would be received is calculated using a cash-out factor based on an associated pool of general account fixed income securities. The cash-out factor is a ratio of the asset investment value of these securities to asset book value. As the investment values change, the cash-out factor is adjusted, impacting the amount the plan receives at measurement date. To determine investment value for each category of assets, we project cash flows. This is done using contractual provisions for the assets, with adjustment for expected prepayments and call provisions. Projected cash flows are discounted to present value for each asset category. Interest rates for discounting are based on current rates on similar new assets in the general account based on asset strategy. Pension Plan Assets The fair value of the qualified pension plan's assets by asset category as of the most recent measurement date was as follows: December 31, 2016 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category U.S. large cap equity portfolios (1) $ $ — $ $ — U.S. small/mid cap equity portfolios (2) — — Balanced asset portfolios (3) — — International equity portfolios (4) — — Fixed income security portfolios (5) — — Real estate investment portfolios (6) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ — $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category U.S. large cap equity portfolios (1) $ $ — $ $ — U.S. small/mid cap equity portfolios (2) — — Balanced asset portfolios (3) — — International equity portfolios (4) — — Fixed income security portfolios (5) — — Real estate investment portfolios (6) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ — $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The portfolios invest primarily in publicly traded equity securities of large U.S. companies. (2) The portfolios invest primarily in publicly traded equity securities of mid-sized and small U.S. companies. (3) The portfolios are a combination of underlying fixed income and equity investment options. These investment options may include balanced, asset allocation, target-date and target-risk investment options. Although typically lower risk than investment options that invest solely in equities, all investment options in this category have the potential to lose value. (4) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies. (5) The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations. (6) The portfolio invests primarily in U.S. commercial real estate properties through a separate account. We had no Level 3 assets in 2016, 2015 and 2014. We have established an investment policy that provides the investment objectives and guidelines for the pension plan. Our investment strategy is to achieve the following: • Obtain a reasonable long-term return consistent with the level of risk assumed and at a cost of operation within prudent levels. Performance benchmarks are monitored. • Ensure sufficient liquidity to meet the emerging benefit liabilities for the plan. • Provide for diversification of assets in an effort to avoid the risk of large losses and maximize the investment return to the pension plan consistent with market and economic risk. In administering the qualified pension plan's asset allocation strategy, we consider the projected liability stream of benefit payments, the relationship between current and projected assets of the plan and the projected actuarial liabilities streams, the historical performance of capital markets adjusted for the perception of future short- and long-term capital market performance and the perception of future economic conditions. According to our investment policy, the target asset allocation for the qualified plan is: Asset category Target allocation U.S. equity portfolios 0% - 45% International equity portfolios 0% - 15% Fixed income security portfolios 30% - 100% Real estate investment portfolios 0% - 10% Other Postretirement Benefit Plan Assets The fair value of the other postretirement benefit plans' assets by asset category as of the most recent measurement date was as follows: December 31, 2016 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category Cash and cash equivalents $ $ $ — $ — Fixed income security portfolios: Fixed income investment funds (1) — U.S. equity portfolios (3) — International equity portfolios (4) — Alternative mutual fund portfolios (5) — — Real estate mutual fund (6) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category Cash and cash equivalents $ $ $ — $ — Fixed income security portfolios: Fixed income investment funds (1) — Principal Life general account investment (2) — — U.S. equity portfolios (3) — International equity portfolios (4) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations. (2) The general account is invested in various fixed income securities. (3) The portfolios invest primarily in publicly traded equity securities of large U.S. companies. (4) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies. (5) The portfolios invest primarily in equities, corporate bonds, foreign currencies, convertible securities and derivatives. (6) The mutual fund invests primarily in U.S. commercial real estate properties. As of December 31, 2016 and 2015, respectively, $81.8 million and $81.2 million of assets in the U.S. equity and international equity portfolios were included in a trust owned life insurance contract. The reconciliation for all assets measured at fair value using significant unobservable inputs (Level 3) is as follows: For the year ended December 31, 2016 Actual return gains Ending Beginning Relating to Relating to Net Transfers Transfers (in millions) Asset category Principal Life general account investment $ $ ) $ ) $ $ — $ — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2015 Actual return gains Ending Beginning Relating to Relating to Net Transfers Transfers (in millions) Asset category Principal Life general account investment $ $ $ — $ ) $ — $ — $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2014 Actual return gains Ending Beginning Relating to Relating to Net Transfers Transfers (in millions) Asset category Principal Life general account investment $ $ $ — $ ) $ — $ — $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The investment strategies and policies for the other postretirement benefit plans are similar to those employed by the qualified pension plan. According to our investment policy, the target asset allocation for the other postretirement benefit plans is: Asset category Target allocation U.S. equity portfolios % International equity portfolios % Fixed income security portfolios % Alternatives % Real estate % Contributions Our funding policy for the qualified pension plan is to fund the plan annually in an amount at least equal to the minimum annual contribution required under ERISA and, generally, not greater than the maximum amount that can be deducted for federal income tax purposes. We do not anticipate contributions will be needed to satisfy the minimum funding requirements of ERISA for our qualified plan. We are unable to estimate the amount that may be contributed, but it is possible that we may fund the plans in 2017 up to $125 million. This includes funding for both our qualified and nonqualified pension plans. While we designate assets to cover the computed liability of the nonqualified plan, the assets are not included as part of the asset balances presented in this footnote as they do not qualify as plan assets in accordance with U.S. GAAP. We may contribute to our other postretirement benefit plans in 2017 pending future analysis. Estimated Future Benefit Payments The estimated future benefit payments, which reflect expected future service, and the expected amount of subsidy receipts under Medicare Part D are: Pension benefits Other postretirement Amount of Medicare (in millions) Year ending December 31: 2017 $ $ $ 2018 2019 2020 2021 2022-2026 The above table reflects the total estimated future benefits to be paid from the plan, including both our share of the benefit cost and the participants' share of the cost, which is funded by their contributions to the plan. The assumptions used in calculating the estimated future benefit payments are the same as those used to measure the benefit obligation for the year ended December 31, 2016. Defined Benefit Pension Plans Supplemental Information Certain key summary data is shown below separately for qualified and nonqualified plans. For the year ended December 31, 2016 2015 Qualified Nonqualified Total Qualified Nonqualified Total (in millions) Amount recognized in statement of financial position Other assets $ — $ — $ — $ — $ — $ — Other liabilities ) ) ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ ) $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount recognized in accumulated other comprehensive loss Total net actuarial loss $ $ $ $ $ $ Prior service benefit ) ) ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax accumulated other comprehensive loss $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Components of net periodic benefit cost Service cost $ $ $ $ $ $ Interest cost Expected return on plan assets ) — ) ) — ) Amortization of prior service benefit ) ) ) ) ) ) Recognized net actuarial loss ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net periodic benefit cost $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other changes recognized in accumulated other comprehensive (income) loss Net actuarial (gain) loss $ ) $ $ $ $ ) $ Amortization of net loss ) ) ) ) ) ) Amortization of prior service benefit ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in pre-tax accumulated other comprehensive (income) loss $ ) $ $ ) $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss $ $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Defined Contribution and Deferred Compensation Plans In addition, we have defined contribution plans that are generally available to all U.S. employees and agents. Eligible participants could not contribute more than $18,000 of their compensation to the plans in 2016. Effective January 1, 2006, we made several changes to the retirement programs. In general, the pension and supplemental executive retirement plan benefit formulas were reduced, and the 401(k) matching contribution was increased. Employees who were ages 47 or older with at least ten years of service on December 31, 2005, could elect to retain the prior benefit provisions and forgo receipt of the additional matching contributions. The employees who elected to retain the prior benefit provisions are referred to as "Grandfathered Choice Participants." We match the Grandfathered Choice Participant's contribution at a 50% contribution rate up to a maximum matching contribution of 3% of the participant's compensation. For all other participants, we match the participant's contributions at a 75% contribution rate up to a maximum matching contribution of 6% of the participant's compensation. The defined contribution plans allow employees to choose among various investment options, including our common stock, which is available through our Employee Stock Ownership Plan ("ESOP"). We contributed $46.6 million, $45.7 million and $41.7 million in 2016, 2015 and 2014, respectively, to our qualified defined contribution plans. The number of shares of our common stock allocated to participants in the ESOP was 2.4 million as of both December 31, 2016 and 2015. As of December 31, 2016 and 2015, the fair value of the ESOP, which includes earned and unearned common stock, was $137.9 million and $108.4 million, respectively. The ESOP's total assets include our common stock and cash. The ESOP purchases our common stock on the open market. The number of shares of our common stock held within the ESOP is treated as outstanding in both our basic and diluted earnings per share calculations. We also have nonqualified deferred compensation plans available to select employees and agents that allow them to defer compensation amounts in excess of limits imposed by federal tax law with respect to the qualified plans. For certain nonqualified deferred compensation plans that include an employer matching contribution, in 2016 we matched the Grandfathered Choice Participant's deferral at a 50% match deferral rate up to a maximum matching deferral of 3% of the participant's compensation. For all

Contingencies, Guarantees and I

Contingencies, Guarantees and Indemnifications	12 Months Ended
	Dec. 31, 2016
Contingencies, Guarantees and Indemnifications
Contingencies, Guarantees and Indemnifications	12. Contingencies, Guarantees and Indemnifications Litigation and Regulatory Contingencies We are regularly involved in litigation, both as a defendant and as a plaintiff, but primarily as a defendant. Litigation naming us as a defendant ordinarily arises out of our business operations as a provider of asset management and accumulation products and services; individual life insurance, specialty benefits insurance and our investment activities. Some of the lawsuits may be class actions, or purport to be, and some may include claims for unspecified or substantial punitive and treble damages. We may discuss such litigation in one of three ways. We accrue a charge to income and disclose legal matters for which the chance of loss is probable and for which the amount of loss can be reasonably estimated. We may disclose contingencies for which the chance of loss is reasonably possible and provide an estimate of the possible loss or range of loss or a statement that such an estimate cannot be made. Finally, we may voluntarily disclose loss contingencies for which the chance of loss is remote in order to provide information concerning matters that potentially expose us to possible losses. In addition, regulatory bodies such as state insurance departments, the SEC, the Financial Industry Regulatory Authority, the Department of Labor and other regulatory agencies regularly make inquiries and conduct examinations or investigations concerning our compliance with, among other things, insurance laws, securities laws, ERISA and laws governing the activities of broker-dealers. We receive requests from regulators and other governmental authorities relating to industry issues and may receive additional requests, including subpoenas and interrogatories, in the future. On December 30, 2015, Mary Ventura, William Littlejohn and Ryan Kadota filed a lawsuit in the United States District Court for the Southern District of Iowa against Principal Management Corporation ("PMC"). The lawsuit alleges PMC breached its fiduciary duty under Section 36(b) of the Investment Company Act by charging excessive fees on the LargeCap Growth I Fund, SmallCap Growth I Fund, SmallCap Fund, High Yield Fund, MidCap Fund and the MidCap Value III Fund. PMC is aggressively defending the lawsuit. On August 29, 2013, American Chemicals & Equipment, Inc. 401(k) Retirement Plan ("ACE") filed a lawsuit in the United States District Court for the Northern District of Alabama against PMC and Principal Global Investors, LLC (the "ACE Defendants"). The lawsuit alleges the ACE Defendants breached their fiduciary duty under Section 36(b) of the Investment Company Act by charging excessive fees on certain of the LifeTime series target date funds. On January 24, 2014, the court granted the motion filed by the ACE Defendants to transfer the case to the Southern District of Iowa. The ACE Defendants were granted summary judgment and the case was dismissed. ACE has appealed that grant of summary judgment and subsequent dismissal to the Eighth Circuit Court of Appeals. The ACE Defendants continue to aggressively defend the lawsuit. In 2008, Principal Life received approximately $440.0 million in connection with the termination of certain structured transactions and the resulting prepayment of Principal Life's investment in those transactions. The transactions involved Lehman Brothers Special Financing Inc. and Lehman Brothers Holdings Inc. (collectively, "Lehman") in various capacities. Subsequent to Lehman's 2008 bankruptcy filing, its bankruptcy estate initiated several lawsuits seeking to recover from numerous sources significant amounts to which it claims entitlement under various theories. We are one of a large group of defendants to this action. The estate's claim against Principal Life, including interest, was approximately $600.0 million. On June 28, 2016, the bankruptcy court granted the Defendants' motion to dismiss directed at common issues and dismissed with prejudice all claims against Principal Life. Defendants, including Principal Life, have requested that the bankruptcy court issue an order directing entry of final judgment consistent with its June 28, 2016, decision. Lehman has the right to appeal an order of final judgment. While the outcome of any pending or future litigation or regulatory matter cannot be predicted, management does not believe any such matter will have a material adverse effect on our business or financial position. As of December 31, 2016, we had no estimated losses accrued related to the legal matters discussed above because we believe the chance of loss from these matters is not probable and the amount of loss cannot be reasonably estimated. We believe all of the litigation contingencies discussed above involve a chance of loss that is either remote or reasonably possible. Unless otherwise noted, all of these matters involve unspecified claim amounts, in which the respective plaintiffs seek an indeterminate amount of damages. To the extent such matters present a reasonably possible chance of loss, we are generally not able to estimate the possible loss or range of loss associated therewith. The outcome of such matters is always uncertain, and unforeseen results can occur. It is possible such outcomes could require us to pay damages or make other expenditures or establish accruals in amounts we could not estimate as of December 31, 2016. Guarantees and Indemnifications In the normal course of business, we have provided guarantees to third parties primarily related to former subsidiaries and joint ventures. The terms of these agreements range in duration and often are not explicitly defined. The maximum exposure under these agreements as of December 31, 2016, was approximately $172.0 million. At inception, the fair value of such guarantees was insignificant. In addition, we believe the likelihood is remote that material payments will be required. Therefore, any liability accrued within our consolidated statements of financial position is insignificant. Should we be required to perform under these guarantees, we generally could recover a portion of the loss from third parties through recourse provisions included in agreements with such parties, the sale of assets held as collateral that can be liquidated in the event performance is required under the guarantees or other recourse generally available to us; therefore, such guarantees would not result in a material adverse effect on our business or financial position. While the likelihood is remote, such outcomes could materially affect net income in a particular quarter or annual period. We manage mandatory privatized social security funds in Chile. By regulation, we have a required minimum guarantee on the funds' relative return. Because the guarantee has no limitation with respect to duration or amount, the maximum exposure of the guarantee in the future is indeterminable. We are also subject to various other indemnification obligations issued in conjunction with divestitures, acquisitions and financing transactions whose terms range in duration and often are not explicitly defined. Certain portions of these indemnifications may be capped, while other portions are not subject to such limitations; therefore, the overall maximum amount of the obligation under the indemnifications cannot be reasonably estimated. At inception, the fair value of such indemnifications was insignificant. In addition, we believe the likelihood is remote that material payments will be required. Therefore, any liability accrued within our consolidated statements of financial position is insignificant. While we are unable to estimate with certainty the ultimate legal and financial liability with respect to these indemnifications, we believe that performance under these indemnifications would not result in a material adverse effect on our business or financial position. While the likelihood is remote, performance under these indemnifications could materially affect net income in a particular quarter or annual period. Guaranty Funds Under state insurance guaranty fund laws, insurers doing business in a state can be assessed, up to prescribed limits, for certain obligations of insolvent insurance companies to policyholders and claimants. A state's fund assesses its members based on their pro rata market share of written premiums in the state for the classes of insurance for which the insolvent insurer was engaged. Some states permit member insurers to recover assessments paid through full or partial premium tax offsets. We accrue liabilities for guaranty fund assessments when an assessment is probable, can be reasonably estimated and when the event obligating us to pay has occurred. While we cannot predict the amount and timing of any future assessments, we have established reserves we believe are adequate for assessments relating to insurance companies that are currently subject to insolvency proceedings. As of December 31, 2016 and 2015, the liability balance for guaranty fund assessments, which is not discounted, was $14.9 million and $15.1 million, respectively, and was reported within other liabilities in the consolidated statements of financial position. As of both December 31, 2016 and 2015, $5.7 million related to premium tax offsets were included in premiums due and other receivables in the consolidated statements of financial position. Operating Leases As a lessee, we lease office space, data processing equipment, office furniture and office equipment under various operating leases. Rental expense for the years ended December 31, 2016, 2015 and 2014, was $40.4 million, $38.0 million and $37.3 million, respectively. The following represents payments due by period for operating lease obligations (in millions): Year ending December 31: 2017 $ 2018 2019 2020 2021 2022 and thereafter ​ ​ ​ ​ ​ Total operating lease obligations Less: Future sublease rental income on noncancelable leases ​ ​ ​ ​ ​ Total future minimum lease payments $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Capital Leases We lease buildings and hardware storage equipment under capital leases. As of December 31, 2016 and 2015, these leases had a gross asset balance of $61.3 million and $63.6 million and accumulated depreciation of $29.9 million and $29.9 million, respectively. Depreciation expense for the years ended December 31, 2016, 2015 and 2014 was $14.8 million, $14.1 million and $14.0 million, respectively. The following represents future minimum lease payments due by period for capital lease obligations (in millions). Year ending December 31: 2017 $ 2018 2019 2020 2021 2022 and thereafter ​ ​ ​ ​ ​ Total Less: Amounts representing interest ​ ​ ​ ​ ​ Net present value of minimum lease payments $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2016
Stockholders' Equity
Stockholders' Equity	13. Stockholders' Equity Preferred Stock On June 30, 2015 we redeemed our 3.0 million shares of series A preferred stock for $300.0 million and our 10.0 million shares of series B preferred stock for $250.0 million. At redemption, we recognized $8.2 million excess redemption value over carrying value of the preferred shares redeemed as an adjustment to determine net income available to common stockholders. Dividend Payments On March 30, 2015 and June 30, 2015, we paid a dividend of $8.2 million and $8.3 million, respectively, equal to $1.39 per share on Series A non-cumulative perpetual preferred stock and equal to $0.41 per share on Series B non-cumulative perpetual preferred stock. Dividends were paid to stockholders of record as of March 12, 2015 and June 11, 2015, respectively. On April 1, 2014; June 30, 2014; September 30, 2014 and December 30, 2014, we paid a dividend of $8.2 million, $8.3 million, $8.2 million and $8.3 million, respectively, equal to $1.39 per share on Series A non-cumulative perpetual preferred stock and equal to $0.41 per share on Series B non-cumulative perpetual preferred stock. Dividends were paid to stockholders of record as of March 13, 2014; June 12, 2014; September 11, 2014 and December 11, 2014, respectively. Reconciliation of Outstanding Shares Series A Series B Common (in millions) Outstanding shares as of January 1, 2014 Shares issued — — Treasury stock acquired — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding shares as of December 31, 2014 Shares issued — — Treasury stock acquired — — ) Preferred stock redemption ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding shares as of December 31, 2015 — — Shares issued — — Treasury stock acquired — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding shares as of December 31, 2016 — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In February 2014, our Board of Directors authorized a share repurchase program of up to $200.0 million of our outstanding common stock, which was completed in March 2015. In February 2015, our Board of Directors authorized a share repurchase program of up to $150.0 million of our outstanding common stock, which was completed in October 2015. In October 2015, our Board of Directors authorized a share repurchase program of up to $150.0 million of our outstanding common stock, which was completed in March 2016. In February 2016, our Board of Directors authorized a share repurchase program of up to $400.0 million of our outstanding common stock. Shares repurchased under these programs are accounted for as treasury stock, carried at cost and reflected as a reduction to stockholders' equity. Other Comprehensive Income (Loss) For the year ended Pre-Tax Tax After-Tax (in millions) Net unrealized gains on available-for-sale securities during the period $ $ ) $ Reclassification adjustment for losses included in net income (1) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on available-for-sale securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale during the period ) ) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale (2) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments during the period ) Reclassification adjustment for gains included in net income (3) ) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized postretirement benefit obligation during the period ) Amortization of prior service cost and actuarial loss included in net periodic benefit cost (4) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrecognized postretirement benefit obligation ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended Pre-Tax Tax After-Tax (in millions) Net unrealized losses on available-for-sale securities during the period $ ) $ $ ) Reclassification adjustment for losses included in net income (1) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized losses on available-for-sale securities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale during the period ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale (2) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments during the period ) Reclassification adjustment for gains included in net income (3) ) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized postretirement benefit obligation during the period ) ) Amortization of prior service cost and actuarial loss included in net periodic benefit cost (4) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrecognized postretirement benefit obligation ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss $ ) $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended Pre-Tax Tax After-Tax (in millions) Net unrealized gains on available-for-sale securities during the period $ $ ) $ Reclassification adjustment for gains included in net income (1) ) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on available-for-sale securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale during the period ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale (2) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments during the period ) Reclassification adjustment for losses included in net income (3) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized postretirement benefit obligation during the period ) ) Amortization of prior service cost and actuarial loss included in net periodic benefit cost (4) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrecognized postretirement benefit obligation ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Pre-tax reclassification adjustments relating to available-for-sale securities are reported in net realized capital gains (losses) on the consolidated statements of operations. (2) Represents the net impact of (1) unrealized gains resulting from reclassification of previously recognized noncredit impairment losses from OCI to net realized capital gains (losses) for fixed maturities with bifurcated OTTI that had additional credit losses or fixed maturities that previously had bifurcated OTTI that have now been sold or are intended to be sold and (2) unrealized losses resulting from reclassification of noncredit impairment losses for fixed maturities with bifurcated OTTI from net realized capital gains (losses) to OCI. (3) See Note 5, Derivative Financial Instruments — Cash Flow Hedges, for further details. (4) Pre-tax amortization of prior service cost and actuarial loss included in net periodic benefit cost, which is comprised of amortization of prior service cost (benefit) and recognized net actuarial (gain) loss, is reported in operating expenses on the consolidated statements of operations. See Note 11, Employee and Agent Benefits — Components of Net Periodic Benefit Cost, for further details. Accumulated Other Comprehensive Income (Loss) Net unrealized Noncredit Net unrealized Foreign Unrecognized Accumulated (in millions) Balances as of January 1, 2014 $ $ ) $ ) $ ) $ ) $ Other comprehensive loss during the period, net of adjustments — ) ) ) Amounts reclassified from AOCI ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balances as of December 31, 2014 ) ) ) Other comprehensive loss during the period, net of adjustments ) — ) ) ) Amounts reclassified from AOCI ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss ) ) ) ) Purchase of subsidiary shares from noncontrolling interest — — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balances as of December 31, 2015 ) ) ) ) Other comprehensive income during the period, net of adjustments ) Amounts reclassified from AOCI — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income ) Purchase of subsidiary shares from noncontrolling interest — — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balances as of December 31, 2016 $ $ ) $ $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncontrolling Interest Interests held by unaffiliated parties in consolidated entities are reflected in noncontrolling interest, which represents the noncontrolling partners' share of the underlying net assets of our consolidated subsidiaries. Noncontrolling interest that is not redeemable is reported in the equity section of the consolidated statements of financial position. The noncontrolling interest holders in certain of our consolidated entities maintain an equity interest that is redeemable at the option of the holder, which may be exercised on varying dates. Since redemption of the noncontrolling interest is outside of our control, this interest is presented on the consolidated statements of financial position line item titled "Redeemable noncontrolling interest." Our redeemable noncontrolling interest primarily relates to consolidated sponsored investment funds for which interests are redeemed at fair value from the net assets of the funds. For our redeemable noncontrolling interest related to other consolidated subsidiaries, redemptions are required to be purchased at fair value or a value based on a formula that management intended to reasonably approximate fair value based on a fixed multiple of earnings over a measurement period. The carrying value of the redeemable noncontrolling interest is compared to the redemption value at each reporting period. Any adjustments to the carrying amount of the redeemable noncontrolling interest for changes in redemption value prior to exercise of the redemption option are determined after the attribution of net income or loss of the subsidiary and are recognized in the redemption value as they occur. Adjustments to the carrying value of redeemable noncontrolling interest result in adjustments to additional paid-in capital and/or retained earnings. Adjustments are recorded in retained earnings to the extent the redemption value of the redeemable noncontrolling interest exceeds its fair value and will impact the numerator in our earnings per share calculations. All other adjustments to the redeemable noncontrolling interest are recorded in additional paid-in capital. Following is a reconciliation of the changes in the redeemable noncontrolling interest (in millions): Balance as of January 1, 2014 $ Net income attributable to redeemable noncontrolling interest Contributions from redeemable noncontrolling interest Distributions to redeemable noncontrolling interest ) Purchase of subsidiary shares from redeemable noncontrolling interest (1) ) Change in redemption value of redeemable noncontrolling interest Other comprehensive income attributable to redeemable noncontrolling interest ) ​ ​ ​ ​ ​ Balance as of December 31, 2014 Net income attributable to redeemable noncontrolling interest Contributions from redeemable noncontrolling interest Distributions to redeemable noncontrolling interest ) Purchase of subsidiary shares from redeemable noncontrolling interest ) Change in redemption value of redeemable noncontrolling interest Other comprehensive income attributable to redeemable noncontrolling interest ) ​ ​ ​ ​ ​ Balance as of December 31, 2015 Net income attributable to redeemable noncontrolling interest Redeemable noncontrolling interest of newly consolidated entities (2) Redeemable noncontrolling interest of deconsolidated entities (3) ) Contributions from redeemable noncontrolling interest Distributions to redeemable noncontrolling interest ) Purchase of subsidiary shares from redeemable noncontrolling interest ) Change in redemption value of redeemable noncontrolling interest Other comprehensive income attributable to redeemable noncontrolling interest ​ ​ ​ ​ ​ Balance as of December 31, 2016 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) During the third quarter of 2014, we increased our ownership stake in Columbus Circle Investors. (2) Effective January 1, 2016, certain sponsored investment funds were consolidated as a result of the implementation of new accounting guidance. See Note 3, Variable Interest Entities, for further details. (3) We deconsolidated certain sponsored investment funds as they no longer met the requirements for consolidation. Dividend Limitations The declaration and payment of our common stock dividends is subject to the discretion of our Board of Directors and will depend on our overall financial condition, results of operations, capital levels, cash requirements, future prospects, receipt of dividends from Principal Life (as described below), risk management considerations and other factors deemed relevant by the Board. No significant restrictions limit the payment of dividends by us, except those generally applicable to corporations incorporated in Delaware. Under Iowa law, Principal Life may pay stockholder dividends only from the earned surplus arising from its business and must receive the prior approval of the Commissioner of Insurance of the State of Iowa (the "Commissioner") to pay a stockholder dividend if such a stockholder dividend would exceed certain statutory limitations. In general, the current statutory limitation is the greater of 10% of Principal Life's policyholder surplus as of the preceding year-end or the net gain from operations from the previous calendar year. Based on this limitation and 2016 statutory results, Principal Life could pay approximately $1,143.3 million in stockholder dividends in 2017 without exceeding the statutory limitation.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Measurements
Fair Value Measurements	14. Fair Value Measurements We use fair value measurements to record fair value of certain assets and liabilities and to estimate fair value of financial instruments not recorded at fair value but required to be disclosed at fair value. Certain financial instruments, particularly policyholder liabilities other than investment contracts, are excluded from these fair value disclosure requirements. Valuation Hierarchy Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (an exit price). The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels. The level in the fair value hierarchy within which the fair value measurement in its entirety falls is determined based on the lowest level input that is significant to the fair value measurement in its entirety considering factors specific to the asset or liability. • Level 1 — Fair values are based on unadjusted quoted prices in active markets for identical assets or liabilities. Our Level 1 assets and liabilities primarily include exchange traded equity securities, mutual funds and U.S. Treasury bonds. • Level 2 — Fair values are based on inputs other than quoted prices within Level 1 that are observable for the asset or liability, either directly or indirectly. Our Level 2 assets and liabilities primarily include fixed maturities (including public and private bonds), equity securities, cash equivalents, derivatives and other investments. • Level 3 — Fair values are based on at least one significant unobservable input for the asset or liability. Our Level 3 assets and liabilities primarily include fixed maturities, real estate and commercial mortgage loan investments of our separate accounts, complex derivatives and embedded derivatives. Determination of Fair Value The following discussion describes the valuation methodologies and inputs used for assets and liabilities measured at fair value on a recurring basis or disclosed at fair value. The techniques utilized in estimating the fair value of financial instruments are reliant on the assumptions used. Care should be exercised in deriving conclusions about our business, its value or financial position based on the fair value information of financial instruments presented below. Fair value estimates are made based on available market information and judgments about the financial instrument at a specific point in time. Such estimates do not consider the tax impact of the realization of unrealized gains or losses. In addition, the disclosed fair value may not be realized in the immediate settlement of the financial instrument. We validate prices through an investment analyst review process, which includes validation through direct interaction with external sources, review of recent trade activity or use of internal models. In circumstances where broker quotes are used to value an instrument, we generally receive one non-binding quote. Broker quotes are validated through an investment analyst review process, which includes validation through direct interaction with external sources and use of internal models or other relevant information. We did not make any significant changes to our valuation processes during 2016. Fixed Maturities Fixed maturities include bonds, ABS, redeemable preferred stock and certain non-redeemable preferred securities. When available, the fair value of fixed maturities is based on quoted prices of identical assets in active markets. These are reflected in Level 1 and primarily include U.S. Treasury bonds and actively traded redeemable corporate preferred securities. When quoted prices of identical assets in active markets are not available, our first priority is to obtain prices from third party pricing vendors. We have regular interaction with these vendors to ensure we understand their pricing methodologies and to confirm they are utilizing observable market information. Their methodologies vary by asset class and include inputs such as estimated cash flows, benchmark yields, reported trades, broker quotes, credit quality, industry events and economic events. Fixed maturities with validated prices from pricing services, which includes the majority of our public fixed maturities in all asset classes, are generally reflected in Level 2. Also included in Level 2 are corporate bonds where quoted market prices are not available, for which an internal model using substantially all observable inputs or a matrix pricing valuation approach is used. In the matrix approach, securities are grouped into pricing categories that vary by sector, rating and average life. Each pricing category is assigned a risk spread based on studies of observable public market data from the investment professionals assigned to specific security classes. The expected cash flows of the security are then discounted back at the current Treasury curve plus the appropriate risk spread. Although the matrix valuation approach provides a fair valuation of each pricing category, the valuation of an individual security within each pricing category may actually be impacted by company specific factors. If we are unable to price a fixed maturity security using prices from third party pricing vendors or other sources specific to the asset class, we may obtain a broker quote or utilize an internal pricing model specific to the asset utilizing relevant market information, to the extent available and where at least one significant unobservable input is utilized. These are reflected in Level 3 in the fair value hierarchy and can include fixed maturities across all asset classes. As of December 31, 2016, less than 1% of our total fixed maturities were Level 3 securities valued using internal pricing models. The primary inputs, by asset class, for valuations of the majority of our Level 2 investments from third party pricing vendors or our internal pricing valuation approach are described below. U.S. Government and Agencies/Non-U.S. Governments. Inputs include recently executed market transactions, interest rate yield curves, maturity dates, market price quotations and credit spreads relating to similar instruments. States and Political Subdivisions. Inputs include Municipal Securities Rulemaking Board reported trades, U.S. Treasury and other benchmark curves, material event notices, new issue data and obligor credit ratings. Corporate. Inputs include recently executed transactions, market price quotations, benchmark yields, issuer spreads and observations of equity and credit default swap curves related to the issuer. For private placement corporate securities valued through the matrix valuation approach inputs include the current Treasury curve and risk spreads based on sector, rating and average life of the issuance. RMBS, CMBS, Collateralized Debt Obligations and Other Debt Obligations. Inputs include cash flows, priority of the tranche in the capital structure, expected time to maturity for the specific tranche, reinvestment period remaining and performance of the underlying collateral including prepayments, defaults, deferrals, loss severity of defaulted collateral and, for RMBS, prepayment speed assumptions. Other inputs include market indices and recently executed market transactions. Equity Securities Equity securities include mutual funds, common stock, non-redeemable preferred stock and required regulatory investments. Fair values of equity securities are determined using quoted prices in active markets for identical assets when available, which are reflected in Level 1. When quoted prices are not available, we may utilize internal valuation methodologies appropriate for the specific asset that use observable inputs such as underlying share prices or the NAV, which are reflected in Level 2. Fair values might also be determined using broker quotes or through the use of internal models or analysis that incorporate significant assumptions deemed appropriate given the circumstances and consistent with what other market participants would use when pricing such securities, which are reflected in Level 3. Derivatives The fair values of exchange-traded derivatives are determined through quoted market prices, which are reflected in Level 1. Exchange-traded derivatives include futures that are settled daily such that their fair value is not reflected in the consolidated statements of financial position. The fair values of derivative instruments cleared through centralized clearinghouses are determined through market prices published by the clearinghouses, which are reflected in Level 2. The clearinghouses may utilize the overnight indexed swap ("OIS") curve in their valuation. The fair values of bilateral OTC derivative instruments are determined using either pricing valuation models that utilize market observable inputs or broker quotes. The majority of our bilateral OTC derivatives are valued with models that use market observable inputs, which are reflected in Level 2. Significant inputs include contractual terms, interest rates, currency exchange rates, credit spread curves, equity prices and volatilities. These valuation models consider projected discounted cash flows, relevant swap curves and appropriate implied volatilities. Certain bilateral OTC derivatives utilize unobservable market data, primarily independent broker quotes that are nonbinding quotes based on models that do not reflect the result of market transactions, which are reflected in Level 3. Our non-cleared derivative contracts are generally documented under ISDA Master Agreements, which provide for legally enforceable set-off and close-out netting of exposures to specific counterparties. Collateral arrangements are bilateral and based on current ratings of each entity. We utilize the LIBOR interest rate curve to value our positions, which includes a credit spread. This credit spread incorporates an appropriate level of nonperformance risk into our valuations given the current ratings of our counterparties, as well as the collateral agreements in place. Counterparty credit risk is routinely monitored to ensure our adjustment for non-performance risk is appropriate. Our centrally cleared derivative contracts are conducted with regulated centralized clearinghouses, which provide for daily exchange of cash collateral equal to the difference in the daily market values of those contracts that eliminates the non-performance risk on these trades. Interest Rate Contracts. For non-cleared contracts we use discounted cash flow valuation techniques to determine the fair value of interest rate swaps using observable swap curves as the inputs. These are reflected in Level 2. For centrally cleared contracts we use published prices from clearinghouses. These are reflected in Level 2. In addition, we have a limited number of complex inflation-linked interest rate swaps, interest rate collars and swaptions that are valued using broker quotes. These are reflected in Level 3. Foreign Exchange Contracts. We use discounted cash flow valuation techniques that utilize observable swap curves and exchange rates as the inputs to determine the fair value of foreign currency swaps. These are reflected in Level 2. Currency forwards are valued using observable market inputs, including forward currency exchange rates. These are reflected in Level 2. In addition, we have a limited number of non-standard currency swaps that are valued using broker quotes. These are reflected within Level 3. Equity Contracts. We use an option pricing model using observable implied volatilities, dividend yields, index prices and swap curves as the inputs to determine the fair value of equity options. These are reflected in Level 2. Credit Contracts. We use either the ISDA Credit Default Swap Standard discounted cash flow model that utilizes observable default probabilities and recovery rates as inputs or broker prices to determine the fair value of credit default swaps. These are reflected in Level 3. In addition, we have a limited number of total return swaps that are valued based on the observable quoted price of underlying equity indices. These are reflected in Level 2. Other Investments Other investments reported at fair value include invested assets of consolidated sponsored investment funds, unconsolidated sponsored investment funds, other investment funds reported at fair value or for which the fair value option was elected, commercial mortgage loans of consolidated VIEs for which the fair value option was elected and equity method real estate investments for which the fair value option was elected. Invested assets of consolidated sponsored investment funds include equity securities, fixed maturities and other investments, for which fair values are determined as previously described, and are reflected in Level 1 and Level 2. The fair value of unconsolidated sponsored investment funds and other investment funds is determined using the NAV of the fund. The NAV of the fund represents the price at which we feel we would be able to initiate a transaction. Investments for which the NAV represents a quoted price in an active market for identical assets are reflected in Level 1. Investments that do not have a quoted price in an active market are reflected in Level 2. Commercial mortgage loans of consolidated VIEs valued using the measurement alternative for CCFEs are reflected in Level 2. These investments are based on the more observable fair value of the liabilities of the consolidated VIEs. The liabilities are affiliated so are not reflected in our consolidated results. Equity method real estate investments for which the fair value option was elected are reflected in Level 3. The equity method real estate investments consist of underlying real estate and debt. The real estate fair value is estimated using a discounted cash flow valuation model that utilizes public real estate market data inputs such as transaction prices, market rents, vacancy levels, leasing absorption, market cap rates and discount rates. The debt fair value is estimated using a discounted cash flow analysis based on our incremental borrowing rate for similar borrowing arrangements. Cash Equivalents Certain cash equivalents are reported at fair value on a recurring basis and include money market instruments and other short-term investments with maturities of three months or less. Fair values of these cash equivalents may be determined using public quotations, when available, which are reflected in Level 1. When public quotations are not available, because of the highly liquid nature of these assets, carrying amounts may be used to approximate fair values, which are reflected in Level 2. Separate Account Assets Separate account assets include equity securities, debt securities and derivative instruments, for which fair values are determined as previously described, and are reflected in Level 1, Level 2 and Level 3. Separate account assets also include commercial mortgage loans, for which the fair value is estimated by discounting the expected total cash flows using market rates that are applicable to the yield, credit quality and maturity of the loans. The market clearing spreads vary based on mortgage type, weighted average life, rating and liquidity. These are reflected in Level 3. Finally, separate account assets include real estate, for which the fair value is estimated using discounted cash flow valuation models that utilize various public real estate market data inputs. In addition, each property is appraised annually by an independent appraiser. The real estate included in separate account assets is recorded net of related mortgage encumbrances for which the fair value is estimated using discounted cash flow analysis based on our incremental borrowing rate for similar borrowing arrangements. The real estate within the separate accounts is reflected in Level 3. Investment Contracts Certain annuity contracts and other investment contracts include embedded derivatives that have been bifurcated from the host contract and are measured at fair value on a recurring basis, which are reflected in Level 3. The key assumptions for calculating the fair value of the embedded derivative liabilities are market assumptions (such as equity market returns, interest rate levels, market volatility and correlations) and policyholder behavior assumptions (such as lapse, mortality, utilization and withdrawal patterns). Risk margins are included in the policyholder behavior assumptions. The assumptions are based on a combination of historical data and actuarial judgment. The embedded derivative liabilities are valued using stochastic models that incorporate a spread reflecting our own creditworthiness. The assumption for our own non-performance risk for investment contracts and any embedded derivatives bifurcated from certain annuity and investment contracts is based on the current market credit spreads for debt-like instruments we have issued and are available in the market. Other Liabilities Certain obligations reported in other liabilities include embedded derivatives to deliver underlying securities of structured investments to third parties. The fair value of the embedded derivatives is calculated based on the value of the underlying securities that are valued based on prices obtained from third party pricing vendors as utilized and described in our discussion of how fair value is determined for fixed maturities, which are reflected in Level 2. Additionally, obligations of consolidated VIEs for which the fair value option was elected are included in other liabilities. The VIEs' unaffiliated obligations are valued utilizing internal pricing models, which are reflected in Level 3. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and liabilities measured at fair value on a recurring basis were as follows: December 31, 2016 Assets/ Amount Fair value hierarchy level Level 1 Level 2 Level 3 (in millions) Assets Fixed maturities, available-for-sale: U.S. government and agencies $ $ — $ $ $ — Non-U.S. governments — States and political subdivisions — — — Corporate — Residential mortgage-backed securities — — — Commercial mortgage-backed securities — — Collateralized debt obligations — — Other debt obligations — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — Fixed maturities, trading — — Equity securities, available-for-sale — Equity securities, trading — — Derivative assets (1) — — Other investments (2) Cash equivalents (3) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sub-total excluding separate account assets Separate account assets — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Investment contracts (4) $ ) $ — $ — $ — $ ) Derivative liabilities (1) ) — — ) ) Other liabilities (4) ) — — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities $ ) $ — $ — $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Assets/ Amount Fair value hierarchy level Level 1 Level 2 Level 3 (in millions) Assets Fixed maturities, available-for-sale: U.S. government and agencies $ $ — $ $ $ — Non-U.S. governments — States and political subdivisions — — — Corporate — Residential mortgage-backed securities — — — Commercial mortgage-backed securities — — Collateralized debt obligations — — Other debt obligations — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — Fixed maturities, trading — Equity securities, available-for-sale — Equity securities, trading — — Derivative assets (1) — — Other investments (2) Cash equivalents (3) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sub-total excluding separate account assets Separate account assets — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Investment contracts (4) $ ) $ — $ — $ — $ ) Derivative liabilities (1) ) — — ) ) Other liabilities (4) ) — — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities $ ) $ — $ — $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Within the consolidated statements of financial position, derivative assets are reported with other investments and derivative liabilities are reported with other liabilities. Refer to Note 5, Derivative Financial Instruments, for further information on fair value by class of derivative instruments. Our derivatives are primarily Level 2, with the exception of certain credit default swaps and other swaps that are Level 3. (2) Primarily includes sponsored investment funds, other investment funds, equity method investments reported at fair value and commercial mortgage loans of consolidated VIEs. (3) Includes money market instruments and short-term investments with a maturity date of three months or less when purchased. (4) Includes bifurcated embedded derivatives that are reported at fair value within the same line item in the consolidated statements of financial position in which the host contract is reported. Other liabilities also include obligations of consolidated VIEs reported at fair value. (5) Certain investments are measured at fair value using the NAV per share (or its equivalent) practical expedient and have not been classified in the fair value hierarchy. These consist of certain fund interests that are restricted until maturity with unfunded commitments totaling $57.6 million and $7.3 million as of December 31, 2016 and December 31, 2015, respectively. Changes in Level 3 Fair Value Measurements The reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) was as follows: For the year ended December 31, 2016 Total realized/unrealized Changes in Beginning Ending Net purchases, Included Included Transfers Transfers (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ $ $ — $ ) $ $ ) Corporate ) ) ) ) Commercial mortgage-backed securities ) ) ) Collateralized debt obligations — ) — — — Other debt obligations — — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) ) ) Fixed maturities, trading — ) — — Equity securities, available-for-sale ) ) — — — ) Derivative assets ) — — — ) Other investments — — — Separate account assets (2) — ) ) Liabilities Investment contracts ) ) — — — ) ) Derivative liabilities ) — — ) Other liabilities ) ) — — — ) ) For the year ended December 31, 2015 Total realized/unrealized Changes in Beginning Ending Net purchases, Included Included Transfers Transfers (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ ) $ $ — $ — $ $ ) Corporate ) ) ) ) Commercial mortgage-backed securities — — — ) — Collateralized debt obligations — ) ) — — — Other debt obligations — — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) ) ) ) Fixed maturities, trading ) — ) — — ) Equity securities, available-for-sale — — — — — — Derivative assets ) — — — ) Other investments — ) — ) Separate account assets (2) — ) Liabilities Investment contracts ) ) — — — ) ) Derivative liabilities ) ) — — ) ) Other liabilities ) ) — — — — ) ) For the year ended December 31, 2014 Changes in Total realized/unrealized Beginning Ending Net purchases, Included Included Transfers Transfers (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ — $ — $ $ ) States and political subdivisions — — ) — ) — — Corporate ) ) ) ) Commercial mortgage-backed securities ) ) ) — — Collateralized debt obligations — ) — Other debt obligations — — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) ) ) Fixed maturities, trading — ) — — Equity securities, available-for-sale ) — ) Derivative assets ) — — — ) Other investments — ) — — Separate account assets (2) — ) ) Liabilities Investment contracts ) ) — — — ) ) Derivative liabilities ) ) — — ) ) Other liabilities ) ) — — — ) ) (1) Both realized gains (losses) and mark-to-market unrealized gains (losses) are generally reported in net realized capital gains (losses) within the consolidated statements of operations. Realized and unrealized gains (losses) on certain fixed maturities, trading and certain derivatives used in relation to certain trading portfolios are reported in net investment income within the consolidated statements of operations. (2) Gains and losses for separate account assets do not impact net income as the change in value of separate account assets is offset by a change in value of separate account liabilities. Foreign currency translation adjustments related to the Principal International segment separate account assets are recorded in AOCI and are offset by foreign currency translation adjustments of the corresponding separate account liabilities. (3) Gross purchases, sales, issuances and settlements were: For the year ended December 31, 2016 Purchases Sales Issuances Settlements Net purchases, (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ Corporate ) — ) Commercial mortgage-backed securities — — ) Collateralized debt obligations — — — ) ) Other debt obligations ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) — ) Fixed maturities, trading — ) — ) ) Derivative assets — — Other investments ) — — Separate account assets (4) ) ) ) Liabilities Investment contracts — — Derivative liabilities — — — Other liabilities — — — For the year ended December 31, 2015 Purchases Sales Issuances Settlements Net purchases, (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ Corporate ) — ) Commercial mortgage-backed securities — — ) Collateralized debt obligations — — — ) ) Other debt obligations — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) — ) Fixed maturities, trading — ) — — ) Derivative assets ) — — Other investments ) — — ) Separate account assets (4) ) ) Liabilities Investment contracts — — Derivative liabilities — — — For the year ended December 31, 2014 Purchases Sales Issuances Settlements Net purchases, (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ ) States and political subdivisions — — — ) ) Corporate ) — ) Commercial mortgage-backed securities — ) — ) ) Collateralized debt obligations — — ) Other debt obligations — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) — ) Fixed maturities, trading — ) — ) ) Equity securities, available-for-sale — ) — — ) Derivative assets ) — — Other investments — — ) ) Separate account assets (4) ) ) ) Liabilities Investment contracts — — Derivative liabilities ) — — Other liabilities — — — (4) Issuances and settlements include amounts related to mortgage encumbrances associated with real estate in our separate accounts. Transfers Transfers of assets and liabilities measured at fair value on a recurring basis between fair value hierarchy levels were as follows: For the year ended December 31, 2016 Transfers out Transfers out Transfers out Transfers out Transfers out Transfers out (in millions) Assets Fixed maturities, available-for- sale: Non-U.S. governments $ — $ — $ — $ — $ — $ Corporate — — — — Commercial mortgage-backed securities — — — — Other debt obligations — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — — — — Separate account assets — — For the year ended December 31, 2015 Transfers out Transfers out Transfers out Transfers out Transfers out Transfers out (in millions) Assets Fixed maturities, available-for- sale: Corporate $ — $ — $ — $ $ — $ Commercial mortgage-backed securities — — — — — Other debt obligations — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — — — — Other investments — — — — Separate account assets — — For the year ended December 31, 2014 Transfers out Transfers out Transfers out Transfers out Transfers out Transfers out (in millions) Assets Fixed maturities, available-for- sale: States and political subdivisions $ — $ — $ — $ — $ — $ Corporate — — — — Commercial mortgage-backed securities — — — — Collateralized debt obligations — — — — Other debt obligations — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — — — — Equity securities, available-for- sale — — — — — Separate account assets — — Transfers between fair value hierarchy levels are recognized at the beginning of the reporting period. Separate account assets transferred between Level 1 and Level 2 during 2016, 2015 and 2014, primarily related to foreign equity securities. When these securities are valued at the close price of the local exchange where the assets traded, they are reflected in Level 1. When events materially affecting the value occur between the close of the local exchange and the New York Stock Exchange, we use adjusted prices determined by a third party pricing vendor to update the foreign market closing prices and the fair value is reflected in Level 2. Other investments transferred from Level 2 into Level 1 during 2015, primarily included assets valued using a NAV with a quoted price in an active market for identical assets as a result of additional analysis to clarify the source of the quoted price. Assets transferred into Level 3 during 2016, 2015 and 2014, primarily included those assets for which we are now unable to obtain pricing from a recognized third party pricing vendor as well as assets that were previously priced using a matrix valuation approach that may no longer be relevant when applied to asset-specific situations. Assets transferred out of Level 3 during 2016, 2015 and 2014, included those for which we are now able to obtain pricing from a recognized third party pricing vendor or from internal models using substantially all market observable information. Additionally, for the year ended December 31, 2015, assets transferred out of Level 3 included assets valued using the measurement alternative for CCFEs for which the corresponding liabilities have the more observable fair value and are reflected in Level 2. Quantitative Information about Level 3 Fair Value Measurements The following table provides quantitative information about the significant unobservable inputs used for recurring fair value measurements categorized within Level 3, excluding assets and liabilities for which significant quantitative unobservable inputs are not developed internally, which primarily consists of those valued using broker quotes or the measurement alternative for CCFEs. Refer to "Assets and liabilities measured at fair value on a recurring basis" for a complete valuation hierarchy summary. December 31, 2016 Assets / Valuation Unobservable Input/range of Weighted (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ Discounted cash flow Discount rate (1) Illiquidity premium 50 basis points ("bps") 50bps Comparability adjustment (25)bps (25)bps Corporate Discounted cash flow Discount rate (1) 1.5% - 7.6% Illiquidity premium 0bps - 60bps 27bps Comparability adjustment 0bps - 20bps 6bps Commercial mortgage-backed securities Discounted cash flow Discount rate (1) 3.1% - 12.8% Probability of default 0.0% - 10.0% Potential loss severity 0.0% - 99.5% Collateralized debt obligations Discounted cash flow Discount rate (1) Probability of default Potential loss severity Other debt obligations Discounted cash flow Discount rate (1) Illiquidity premium 500bps 500bps Fixed maturities, trading Discounted cash flow Discount rate (1) 2.3% - 9.0% Illiquidity premium 0bps - 300bps 240bps Other investments Discounted cash flow — equity method real estate investments Discount rate (1) Terminal capitalization rate Average market rent growth rate Discounted cash flow — equity method real estate investments — debt Loan to value Credit spread rate Separate account assets Discounted cash flow — mortgage loans Discount rate (1) 1.4% - 5.3% Illiquidity premium 0bps - 60bps 13bps Credit spread rate 83bps - 472bps 227bps Discounted cash flow — real estate Discount rate (1) 5.8% - 16.2% Terminal capitalization rate 4.3% - 9.3% Average market rent growth rate 1

Statutory Insurance Financial I

Statutory Insurance Financial Information	12 Months Ended
	Dec. 31, 2016
Statutory Insurance Financial Information
Statutory Insurance Financial Information	15. Statutory Insurance Financial Information Principal Life, the largest indirect subsidiary of PFG, prepares statutory financial statements in accordance with the accounting practices prescribed or permitted by the Insurance Division of the Department of Commerce of the State of Iowa (the "State of Iowa"). The State of Iowa recognizes only statutory accounting practices prescribed or permitted by the State of Iowa for determining and reporting the financial condition and results of operations of an insurance company to determine its solvency under the Iowa Insurance Law. The National Association of Insurance Commissioners' ("NAIC") Accounting Practices and Procedures Manual has been adopted as a component of prescribed practices by the State of Iowa. The Commissioner has the right to permit other specific practices that deviate from prescribed practices. For the years ended, December 31, 2016, 2015 and 2014, Principal Life's use of prescribed statutory accounting practices resulted in higher (lower) statutory net income of $3.8 million, $(2.1) million and $6.4 million, respectively, relative to the accounting practices and procedures of the NAIC due to its accounting for derivatives that hedge some of its equity indexed products. In addition, as of December 31, 2016 and 2015, Principal Life's permitted statutory accounting practice relating to variable annuities with a guaranteed living benefit rider resulted in lower statutory surplus of $180.5 million and $158.1 million, respectively, relative to carrying certain interest rate swaps at book value rather than fair value, as if they received hedge accounting treatment for statutory. Statutory accounting practices differ from U.S. GAAP primarily due to charging policy acquisition costs to expense as incurred, establishing reserves using different actuarial assumptions, valuing investments on a different basis and not admitting certain assets, including certain net deferred income tax assets. Principal Life cedes certain term and universal life insurance statutory reserves to our affiliated reinsurance subsidiaries on a funds withheld coinsurance basis. The reserves are secured by cash, invested assets and financing provided by highly rated third parties. As of December 31, 2016 and 2015, our affiliated reinsurance subsidiaries assumed statutory reserves of $4,734.0 million and $3,934.2 million from Principal Life, respectively. In the states of Vermont and Delaware, the affiliated reinsurers had permitted and prescribed practices allowing for the admissibility of certain assets backing these reserves. As of December 31, 2016 and 2015, assets admitted under these practices totaled $1,809.0 million and $1,447.0 million, respectively. Life and health insurance companies are subject to certain risk-based capital ("RBC") requirements as specified by the NAIC. Under those requirements, the amount of capital and surplus maintained by a life and health insurance company is to be determined based on the various risk factors related to it. As of December 31, 2016, Principal Life met the minimum RBC requirements. Statutory net income and statutory capital and surplus of Principal Life were as follows: As of or for the year 2016 2015 2014 (in millions) Statutory net income $ $ $ Statutory capital and surplus

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2016
Segment Information
Segment Information	16. Segment Information We provide financial products and services through the following segments: Retirement and Income Solutions, Principal Global Investors, Principal International and U.S. Insurance Solutions. In addition, we have a Corporate segment. The segments are managed and reported separately because they provide different products and services, have different strategies or have different markets and distribution channels. During fourth quarter 2016, we decided to move long-term care, a business we exited and fully reinsured in 1997, from the U.S. Insurance Solutions segment to the Corporate segment to align it with the management of other exited businesses in the Corporate segment. This change has been applied retrospectively to our segment financial information but did not impact our consolidated financial statements. The Retirement and Income Solutions segment provides retirement and related financial products and services primarily to businesses, their employees and other individuals. The Principal Global Investors segment provides asset management services to our asset accumulation business, our insurance operations, the Corporate segment and third party clients. This segment also includes our mutual fund business. The Principal International segment has operations in Latin America (Brazil, Chile and Mexico) and Asia (China, Hong Kong Special Administrative Region, India and Southeast Asia). We focus on locations with large middle classes, favorable demographics and growing long-term savings, ideally with voluntary or mandatory pension markets. We entered these locations through acquisitions, start-up operations and joint ventures. The U.S. Insurance Solutions segment provides specialty benefits insurance, which consists of group dental and vision insurance, individual and group disability insurance, group life insurance and non-medical fee-for-service claims administration, and individual life insurance throughout the United States. Our Corporate segment manages the assets representing capital that has not been allocated to any other segment. Financial results of the Corporate segment primarily reflect our financing activities (including financing costs and preferred stock dividends), income on capital not allocated to other segments, inter-segment eliminations, income tax risks and certain income, expenses and other adjustments not allocated to the segments based on the nature of such items. Results of Principal Securities, Inc., our retail broker-dealer and registered investment advisor, and our exited group medical and long-term care insurance businesses are reported in this segment. Management uses segment pre-tax operating earnings in evaluating performance, which is consistent with the financial results provided to and discussed with securities analysts. We determine segment pre-tax operating earnings by adjusting U.S. GAAP income before income taxes for pre-tax net realized capital gains (losses), as adjusted, pre-tax other adjustments that management believes are not indicative of overall operating trends and certain adjustments related to equity method investments and noncontrolling interest. Pre-tax net realized capital gains (losses), as adjusted, are net of related changes in the amortization pattern of DAC and related actuarial balances, recognition of deferred front-end fee revenues for sales charges on retirement and life insurance products and services, amortization of hedge accounting book value adjustments for certain discontinued hedges, net realized capital gains and losses distributed, certain adjustments related to equity method investments, certain adjustments related to sponsored investment funds and certain market value adjustments to fee revenues. Pre-tax net realized capital gains (losses), as adjusted, exclude periodic settlements and accruals on derivative instruments not designated as hedging instruments and exclude certain market value adjustments of embedded derivatives and realized capital gains (losses) associated with our exited group medical insurance business. Segment operating revenues exclude net realized capital gains (losses) (except periodic settlements and accruals on derivatives not designated as hedging instruments), including their impact on recognition of front-end fee revenues, certain market value adjustments to fee revenues, certain adjustments related to equity method investments, certain adjustments related to sponsored investment funds and amortization of hedge accounting book value adjustments for certain discontinued hedges; certain adjustments related to equity method investments, pre-tax other adjustments management believes are not indicative of overall operating trends and revenue from our exited group medical insurance business. While these items may be significant components in understanding and assessing the consolidated financial performance, management believes the presentation of segment pre-tax operating earnings enhances the understanding of our results of operations by highlighting pre-tax earnings attributable to the normal, ongoing operations of the business. The accounting policies of the segments are consistent with the accounting policies for the consolidated financial statements, with the exception of: (1) pension and other postretirement employee benefit cost allocations and (2) income tax allocations. For purposes of determining operating earnings, the segments are allocated the service component of pension and other postretirement benefit costs. The Corporate segment reflects the non-service components of pension and other postretirement benefit costs as assumptions are established and funding decisions are managed from a company-wide perspective. The Corporate segment functions to absorb the risk inherent in interpreting and applying tax law. For purposes of determining operating earnings, the segments are allocated tax adjustments consistent with the positions we took on tax returns. The Corporate segment results reflect any differences between the tax returns and the estimated resolution of any disputes. The following tables summarize select financial information by segment, including operating revenues for our products and services, and reconcile segment totals to those reported in the consolidated financial statements: December 31, 2016 December 31, 2015 (in millions) Assets: Retirement and Income Solutions $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated assets $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2016 2015 2014 (in millions) Operating revenues by segment: Retirement and Income Solutions: Retirement and Income Solutions — Fee $ $ $ Retirement and Income Solutions — Spread ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Retirement and Income Solutions (1) Principal Global Investors (2) Principal International U.S. Insurance Solutions: Specialty benefits insurance Individual life insurance Eliminations ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total U.S. Insurance Solutions Corporate ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total segment operating revenues Net realized capital gains (losses), net of related revenue adjustments ) ) Certain adjustments related to equity method investments ) ) ) Other income on a tax indemnification — — Exited group medical insurance business — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues per consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax operating earnings (losses) by segment: Retirement and Income Solutions $ $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total segment pre-tax operating earnings Pre-tax net realized capital gains (losses), as adjusted (3) ) ) Pre-tax other adjustments (4) ) ) Certain adjustments related to equity method investments and noncontrolling interest ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes per consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Reflects inter-segment revenues of $373.3 million, $424.5 million and $440.1 million for the years ended December 31, 2016, 2015 and 2014, respectively. (2) Reflects inter-segment revenues of $235.7 million, $220.6 million and $206.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. (3) Pre-tax net realized capital gains (losses), as adjusted, is derived as follows: For the year ended 2016 2015 2014 (in millions) Net realized capital gains (losses) $ $ ) $ Certain derivative and hedging-related adjustments ) ) ) Certain market value adjustments to fee revenues ) ) — Certain adjustments related to equity method investments — — Certain adjustments related to sponsored investment funds — Recognition of front-end fee revenue ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses), net of related revenue adjustments ) ) Amortization of deferred acquisition costs and other actuarial balances ) ) ) Capital (gains) losses distributed ) ) Certain market value adjustments of embedded derivatives ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax net realized capital gains (losses), as adjusted (a) $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (a) As adjusted before noncontrolling interest capital gains (losses) and net realized capital gains (losses) associated with exited group medical insurance business. (4) For the year ended December 31, 2016, pre-tax other adjustments included the negative effect of one-time costs incurred to extinguish long-term debt. For the year ended December 31, 2015, pre-tax other adjustments included the positive effect of the impact of a court ruling on some uncertain tax positions ($15.1 million) and the negative effect of losses associated with our exited group medical insurance business that did not qualify for discontinued operations accounting treatment under U.S. GAAP ($3.4 million). For the year ended December 31, 2014, pre-tax other adjustments included the negative effect of the impact of (a) a court ruling on some uncertain tax positions ($62.2 million) and (b) the effect of losses associated with our exited group medical insurance business that did not qualify for discontinued operations accounting treatment under U.S. GAAP ($0.9 million). The following is a summary of income tax expense (benefit) allocated to our segments for purposes of determining operating earnings. Segment income taxes are reconciled to income taxes reported on our consolidated statements of operations. For the year ended 2016 2015 2014 (in millions) Income tax expense (benefit) by segment: Retirement and Income Solutions $ $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total segment income taxes from operating earnings Tax benefit related to net realized capital losses, as adjusted ) ) ) Tax expense (benefit) related to other after-tax adjustments ) ) Certain adjustments related to equity method investments and noncontrolling interest ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income taxes per consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following is a summary of depreciation and amortization expense allocated to our segments for purposes of determining pre-tax operating earnings. Segment depreciation and amortization is reconciled to depreciation and amortization included in operating expenses in our consolidated statements of operations. For the year ended 2016 2015 2014 (in millions) Depreciation and amortization expense by segment: Retirement and Income Solutions $ $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total depreciation and amortization expense included in our consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2016
Stock-Based Compensation Plans
Stock-Based Compensation Plans	17. Stock-Based Compensation Plans As of December 31, 2016, we had the 2014 Stock Incentive Plan, the Employee Stock Purchase Plan, the 2014 Directors Stock Plan, the Long-Term Performance Plan, the Amended and Restated 2010 Stock Incentive Plan, the 2005 Directors Stock Plan, the Stock Incentive Plan and the Directors Stock Plan ("Stock-Based Compensation Plans"). As of May 20, 2014, no new grants will be made under the Amended and Restated 2010 Stock Incentive Plan or the 2005 Directors Stock Plan. No grants have been made under the Stock Incentive Plan, the Directors Stock Plan or the Long-Term Performance Plan since at least 2005. Under the terms of the 2014 Stock Incentive Plan, grants may be nonqualified stock options, incentive stock options qualifying under Section 422 of the Internal Revenue Code, restricted stock, restricted stock units, stock appreciation rights, performance shares, performance units or other stock-based awards. The 2014 Directors Stock Plan provides for the grant of nonqualified stock options, restricted stock, restricted stock units or other stock-based awards to our nonemployee directors. To date, we have not granted any incentive stock options, restricted stock or performance units under any plans. As of December 31, 2016, the maximum number of new shares of common stock available for grant under the 2014 Stock Incentive Plan and the 2014 Directors Stock Plan was 9.9 million. For awards with graded vesting, we use an accelerated expense attribution method. The compensation cost that was charged against income for stock-based awards granted under the Stock-Based Compensation Plans was as follows: For the year ended 2016 2015 2014 (in millions) Compensation cost $ $ $ Related income tax benefit Capitalized as part of an asset Nonqualified Stock Options Nonqualified stock options were granted to certain employees under the 2014 Stock Incentive Plan, the Amended and Restated 2010 Stock Incentive Plan and the Stock Incentive Plan. Options outstanding were granted at an exercise price equal to the fair market value of our common stock on the date of grant, and expire ten years after the grant date. These options have graded vesting over a three-year period, except in the case of specific types of terminations. Total options granted were 1.1 million, 0.6 million and 0.6 million during 2016, 2015 and 2014, respectively. The following is a summary of the status of all of our stock option plans: Number of options Weighted- Intrinsic value (in millions) (in millions) Options outstanding as of January 1, 2016 $ Granted Exercised Expired ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding as of December 31, 2016 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options vested or expected to vest as of December 31, 2016 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable as of December 31, 2016 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The total intrinsic value of stock options exercised was $25.7 million, $17.4 million and $25.4 million during 2016, 2015, and 2014, respectively. The following is a summary of weighted-average remaining contractual lives for stock options outstanding and the range of exercise prices on the stock options as of December 31, 2016: Range of exercise prices Number of options Weighted- (in millions) $11.07 - $21.69 $21.70 - $32.32 $32.33 - $42.95 $42.96 - $53.58 $53.59 - $64.22 ​ ​ ​ ​ ​ ​ ​ ​ $11.07 - $64.22 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The weighted-average remaining contractual lives for stock options exercisable is approximately 3.0 years as of December 31, 2016. The fair value of stock options is estimated using the Black-Scholes option pricing model. The following is a summary of the assumptions used in this model for the stock options granted during the period: For the year ended Options 2016 2015 2014 Expected volatility % % % Expected term (in years) Risk-free interest rate % % % Expected dividend yield % % % Weighted average estimated fair value $ $ $ We determine expected volatility based on a combination of historical volatility using daily price observations and implied volatility from traded options on our common stock. We believe that incorporating both historical and implied volatility into our expected volatility assumption calculation better reflects market expectations. The expected term represents the period of time that options granted are expected to be outstanding. We determine expected term using historical exercise and employee termination data. The risk-free rate for periods within the expected term of the option is based on the U.S. Treasury risk-free interest rate in effect at the time of grant. The dividend yield is based on historical dividend distributions compared to the closing price of our common shares on the grant date. As of December 31, 2016, we had $2.9 million of total unrecognized compensation costs related to nonvested stock options. The cost is expected to be recognized over a weighted-average service period of approximately 1.7 years. Cash received from stock options exercised under these share-based payment arrangements during 2016, 2015 and 2014 was $15.3 million, $52.7 million and $56.1 million, respectively. The actual tax benefits realized for the tax deductions for options exercised under these share-based payment arrangements during 2016, 2015 and 2014 was $9.0 million, $6.0 million and $8.6 million, respectively. Performance Share Awards We granted performance share awards to certain employees under the 2014 Stock Incentive Plan and the Amended and Restated 2010 Stock Incentive Plan. The performance share awards are treated as an equity award and are paid in shares. Whether the performance shares are earned depends upon the participant's continued employment through the performance period (except in the case of specific types of terminations) and our performance against three-year goals set at the beginning of the performance period. Performance goals based on various factors must be achieved for any of the performance shares to be earned. If the performance requirements are not met, the performance shares will be forfeited, no compensation cost will be recognized and any previously recognized compensation cost will be reversed. These awards have no maximum contractual term. Dividend equivalents are credited on performance shares outstanding as of the record date. These dividend equivalents are only paid on the shares released. Total performance share awards granted were 0.3 million, 0.3 million and 0.3 million in 2016, 2015 and 2014, respectively. The following is a summary of activity for the nonvested performance share awards: Number of Weighted- (in millions) Nonvested performance share awards as of January 1, 2016 $ Granted Vested ​ ​ ​ ​ ​ ​ ​ ​ Nonvested performance share awards as of December 31, 2016 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The total intrinsic value of performance share awards vested was $18.1 million, $20.1 million and $11.4 million during 2016, 2015 and 2014, respectively. Performance share awards above represent initial target awards and do not reflect potential increases or decreases resulting from the final performance objectives to be determined at the end of the respective performance period. The actual number of shares to be awarded at the end of each performance period will range between 0% and 150% of the initial target awards. The fair value of performance share awards is determined based on the closing stock price of our common shares on the grant date. The weighted-average grant-date fair value of performance share awards granted during 2016, 2015 and 2014 was $37.38, $51.33 and $44.88, respectively. As of December 31, 2016, we had $4.5 million of total unrecognized compensation cost related to nonvested performance share awards granted. The cost is expected to be recognized over a weighted-average service period of approximately 1.5 years. Actual tax benefits realized for the tax deductions for performance share awards paid out under these share-based payment arrangements for 2016, 2015 and 2014 was $4.8 million, $7.4 million and $4.0 million, respectively. Restricted Stock Units We issue restricted stock units under the 2014 Stock Incentive Plan, the 2014 Directors Stock Plan, the Amended and Restated 2010 Stock Incentive Plan, the 2005 Directors Stock Plan, the Stock Incentive Plan, and the Directors Stock Plan. Restricted stock units are treated as an equity award and are paid in shares. These awards have no maximum contractual term. Dividend equivalents are credited on restricted stock units outstanding as of the record date. These dividend equivalents are only paid on the shares released. Restricted stock units granted were 1.3 million, 0.9 million and 0.9 million in 2016, 2015 and 2014, respectively. Restricted stock units were issued to certain employees and agents pursuant to the 2014 Stock Incentive Plan, the Amended and Restated 2010 Stock Incentive Plan and Stock Incentive Plan. Under these plans, awards have graded or cliff vesting over a three-year service period. When service for PFG ceases (except in the case of specific types of terminations), all vesting stops and unvested units are forfeited. Pursuant to the 2014 Directors Stock Plan and the 2005 Directors Stock Plan, restricted stock units are granted to each non-employee director in office immediately following each annual meeting of stockholders and, at the discretion of the Nominating and Governance Committee, to each person who becomes a member of the Board other than on the date of the annual meeting of stockholders. Under these plans, awards are granted on an annual basis and cliff vest after a one-year service period. When service to PFG ceases, all vesting stops and unvested units are forfeited. The following is a summary of activity for the nonvested restricted stock units: Number of Weighted- (in millions) Nonvested restricted stock units as of January 1, 2016 $ Granted Vested ​ ​ ​ ​ ​ ​ ​ ​ Nonvested restricted stock units as of December 31, 2016 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The total intrinsic value of restricted stock units vested was $46.2 million, $53.6 million and $38.5 during 2016, 2015 and 2014, respectively. The fair value of restricted stock units is determined based on the closing stock price of our common shares on the grant date. The weighted-average grant-date fair value of restricted stock units granted during 2016, 2015 and 2014 was $37.59, $51.35 and $45.03, respectively. As of December 31, 2016, we had $45.0 million of total unrecognized compensation cost related to nonvested restricted stock unit awards granted under these plans. The cost is expected to be recognized over a weighted-average period of approximately 1.7 years. The actual tax benefits realized for the tax deductions for restricted stock unit payouts under these share-based payment arrangements for 2016, 2015 and 2014 was $16.1 million, $18.8 million and $12.8 million, respectively. Employee Stock Purchase Plan Under our Employee Stock Purchase Plan, participating employees have the opportunity to purchase shares of our common stock on a semi-annual basis. Employees may purchase up to $25,000 worth of company stock each year. Employees may purchase shares of our common stock at a price equal to 85% of the shares' fair market value as of the beginning or end of the purchase period, whichever is lower. Under the Employee Stock Purchase Plan, employees purchased 0.7 million, 0.6 million and 0.5 million shares during 2016, 2015 and 2014, respectively. We recognize compensation expense for the fair value of the discount granted to employees participating in the employee stock purchase plan in the period of grant. Shares of the Employee Stock Purchase Plan are treated as an equity award. The weighted-average fair value of the discount on the stock purchased was $14.00, $7.29 and $8.94 during 2016, 2015 and 2014, respectively. The total intrinsic value of the Employee Stock Purchase Plan shares settled was $10.2 million, $4.1 million and $4.7 million during 2016, 2015 and 2014, respectively. Cash received from shares issued under these share-based payment arrangements for 2016, 2015 and 2014 was $25.5 million, $23.4 million and $22.2 million, respectively. The actual tax benefit realized for the tax deductions for the settlement of the share-based payment arrangements for 2016, 2015 and 2014 was $0.6 million, $0.6 million and $1.1 million, respectively. As of December 31, 2016, a total of 3.4 million of new shares were available to be made issuable by us for this plan.

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Common Share
Earnings Per Common Share	18. Earnings Per Common Share The computations of the basic and diluted per share amounts were as follows: For the year ended 2016 2015 2014 (in millions, except per Net income $ $ $ Subtract: Net income attributable to noncontrolling interest Preferred stock dividends — Excess of redemption value over carrying value of preferred shares redeemed — — Adjustments to redemption amounts of redeemable noncontrolling interests — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares outstanding: Basic Dilutive effects: Stock options Restricted stock units Performance share awards ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per common share: Basic $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The calculation of diluted earnings per share for the years ended December 31, 2016, 2015 and 2014, excludes the incremental effect related to certain outstanding stock-based compensation grants due to their anti-dilutive effect.

Quarterly Results of Operations

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Results of Operations (Unaudited)
Quarterly Results of Operations (Unaudited)	19. Quarterly Results of Operations (Unaudited) The following is a summary of unaudited quarterly results of operations. For the three months ended, December 31 September 30 June 30 March 31 (in millions, except per share data) 2016 Total revenues $ $ $ $ Total expenses Net income Net income available to common stockholders Basic earnings per common share for net income available to common stockholders Diluted earnings per common share for net income available to common stockholders 2015 Total revenues $ $ $ $ Total expenses Net income Net income available to common stockholders Basic earnings per common share for net income available to common stockholders Diluted earnings per common share for net income available to common stockholders

Condensed Consolidating Financi

Condensed Consolidating Financial Information	12 Months Ended
	Dec. 31, 2016
Condensed Consolidating Financial Information
Condensed Consolidating Financial Information	20. Condensed Consolidating Financial Information Principal Life has established special purpose entities to issue secured medium-term notes. Under the program, the payment obligations of principal and interest on the notes are secured by funding agreements issued by Principal Life. Principal Life's payment obligations on the funding agreements are fully and unconditionally guaranteed by PFG. All of the outstanding stock of Principal Life is indirectly owned by PFG and PFG is the only guarantor of the payment obligations of the funding agreements. The following tables set forth condensed consolidating financial information of (i) PFG, (ii) Principal Life, (iii) Principal Financial Services, Inc. ("PFS") and all other direct and indirect subsidiaries of PFG on a combined basis and (iv) the eliminations necessary to arrive at the information for PFG on a consolidated basis as of December 31, 2016 and December 31, 2015, and for the years ended December 31, 2016, 2015 and 2014. In presenting the condensed consolidating financial statements, the equity method of accounting has been applied to (i) PFG's interest in all direct subsidiaries of PFG, (ii) Principal Life's interest in all direct subsidiaries of Principal Life and (iii) PFS's interest in Principal Life even though all such subsidiaries meet the requirements to be consolidated under U.S. GAAP. Earnings of subsidiaries are, therefore, reflected in the parent's investment and earnings. All intercompany balances and transactions, including elimination of the parent's investment in subsidiaries, between PFG, Principal Life and PFS and all other subsidiaries have been eliminated, as shown in the column "Eliminations." These condensed consolidating financial statements should be read in conjunction with the consolidated financial statements. The financial information may not necessarily be indicative of results of operations, cash flows or financial position had the subsidiaries operated as independent entities. Condensed Consolidating Statements of Financial Position Principal Principal Life Principal Financial Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ $ $ ) $ Fixed maturities, trading — — Equity securities, available-for-sale — — Equity securities, trading — — Mortgage loans — ) Real estate — — Policy loans — — Investment in unconsolidated entities ) Other investments ) Cash and cash equivalents ) Accrued investment income — ) Premiums due and other receivables — ) Deferred acquisition costs — — Property and equipment — — Goodwill — — Other intangibles — — Separate account assets — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ $ $ ) $ Future policy benefits and claims — ) Other policyholder funds — ) Short-term debt — — — Long-term debt — ) Income taxes currently payable — — ) Deferred income taxes — ) Separate account liabilities — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive income (loss) ) ) ) ) Treasury stock, at cost ) — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Financial Position Principal Principal Life Principal Financial Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ $ $ ) $ Fixed maturities, trading — — Equity securities, available-for-sale — — Equity securities, trading — — Mortgage loans — ) Real estate — — Policy loans — — Investment in unconsolidated entities ) Other investments ) Cash and cash equivalents ) Accrued investment income — ) Premiums due and other receivables — ) Deferred acquisition costs — — Property and equipment — — Goodwill — — Other intangibles — — Separate account assets — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ $ $ ) $ Future policy benefits and claims — ) Other policyholder funds — ) Short-term debt — — — Long-term debt — ) Income taxes currently payable — — ) Deferred income taxes — ) Separate account liabilities — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive income (loss) ) ) ) ) Treasury stock, at cost ) — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Life Principal Financial Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains, excluding impairment losses on available-for-sale securities — Net other-than-temporary impairment losses on available-for-sale securities — ) ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — ) Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) Income taxes (benefits) ) ) Equity in the net income (loss) of subsidiaries ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Life Principal Financial Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains (losses), excluding impairment losses on available-for-sale securities — ) — ) Net other-than-temporary impairment losses on available-for-sale securities — ) ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified from other comprehensive income — ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — ) Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) Income taxes (benefits) ) ) Equity in the net income of subsidiaries ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — Excess of redemption value over carrying value of preferred shares redeemed — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive loss ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Life Principal Financial Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains (losses), excluding impairment losses on available-for-sale securities — ) — Net other-than-temporary impairment (losses) recoveries on available-for-sale securities — ) — Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — ) Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) Income taxes (benefits) ) ) ) Equity in the net income (loss) of subsidiaries ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income (loss) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Life Principal Financial Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — ) ) ) Sales — — Maturities — — Mortgage loans acquired or originated — ) ) ) Mortgage loans sold or repaid — ) Real estate acquired — — ) — ) Net purchases of property and equipment ) ) ) — ) Dividends and returns of capital received from unconsolidated entities ) — Net change in other investments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — ) — — ) Excess tax benefits from share-based payment arrangements — Purchase of subsidiary shares from noncontrolling interest — — ) ) Sale of subsidiary shares to noncontrolling interest — — ) — Dividends to common stockholders ) — — — ) Issuance of long-term debt — Principal repayments of long-term debt ) — ) ) ) Net repayments of short-term borrowings — — ) — ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — Investment contract withdrawals — ) ) — ) Net increase in banking operation deposits — — — Other — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) financing activities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Life Principal Financial Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ $ Investing activities Available-for-sale securities: Purchases — ) ) — ) Sales — ) Maturities — — Mortgage loans acquired or originated — ) ) ) Mortgage loans sold or repaid — ) Real estate acquired — ) ) — ) Net purchases of property and equipment — ) ) — ) Purchase of interests in subsidiaries, net of cash acquired — — ) — ) Dividends and returns of capital received from (contributed to) unconsolidated entities ) ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — ) — — ) Excess tax benefits from share-based payment arrangements — Purchase of subsidiary shares from noncontrolling interest — — ) ) Sale of subsidiary shares to noncontrolling interest — — ) — Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Preferred stock redemption ) — — — ) Issuance of long-term debt — ) Principal repayments of long-term debt — — ) ) Net proceeds from short-term borrowings — — — Dividends and capital paid to parent — ) ) — Investment contract deposits — — Investment contract withdrawals — ) ) — ) Net increase in banking operation deposits — — — Other — ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase in cash and cash equivalents Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Life Principal Financial Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — ) ) ) Sales — — Maturities — — Mortgage loans acquired or originated — ) ) ) Mortgage loans sold or repaid — ) Real estate acquired — ) ) — ) Net purchases of property and equipment — ) ) — ) Dividends and returns of capital received from unconsolidated entities ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — ) — — ) Excess tax benefits from share-based payment arrangements — Purchase of subsidiary shares from noncontrolling interest — — ) ) Sale of subsidiary shares to noncontrolling interest — — ) — Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Issuance of long-term debt — — ) Principal repayments of long-term debt — ) ) ) Net repayments of short-term borrowings — — ) — ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — Investment contract withdrawals — ) ) — ) Net increase in banking operation deposits — — — Other — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) ) Cash and cash equivalents at beginning of period ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ On May 7, 2014, our shelf registration statement was filed with the SEC and became effective, replacing the shelf registration that had been in effect since May 2011. Under our current shelf registration, we have the ability to issue, in unlimited amounts, unsecured senior debt securities or subordinated debt securities, junior subordinated debt, preferred stock, common stock, warrants, depository shares, stock purchase contracts and stock purchase units of PFG, trust preferred securities of three subsidiary trusts and guarantees by PFG of these trust preferred securities. Our wholly owned subsidiary, PFS, may guarantee, fully and unconditionally or otherwise, our obligations with respect to any non-convertible securities, other than common stock, described in the shelf registration. The following tables set forth condensed consolidating financial information of (i) PFG, (ii) PFS, (iii) Principal Life and all other direct and indirect subsidiaries of PFG on a combined basis and (iv) the eliminations necessary to arrive at the information for PFG on a consolidated basis as of December 31, 2016 and December 31, 2015, and for the years ended December 31, 2016, 2015 and 2014. In presenting the condensed consolidating financial statements, the equity method of accounting has been applied to (i) PFG's interest in all direct subsidiaries of PFG and (ii) PFS's interest in Principal Life and all other subsidiaries, where applicable, even though all such subsidiaries meet the requirements to be consolidated under U.S. GAAP. Earnings of subsidiaries are, therefore, reflected in the parent's investment and earnings. All intercompany balances and transactions, including elimination of the parent's investment in subsidiaries, between PFG, PFS and Principal Life and all other subsidiaries have been eliminated, as shown in the column "Eliminations." These condensed consolidating financial statements should be read in conjunction with the consolidated financial statements. The financial information may not necessarily be indicative of results of operations, cash flows or financial position had the subsidiaries operated as independent entities. Condensed Consolidating Statements of Financial Position Principal Principal Principal Life Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ — $ $ — $ Fixed maturities, trading — — — Equity securities, available-for-sale — — — Equity securities, trading — — — Mortgage loans — — — Real estate — — — Policy loans — — — Investment in unconsolidated entities ) Other investments — Cash and cash equivalents ) Accrued investment income — — Premiums due and other receivables — ) Deferred acquisition costs — — — Property and equipment — — — Goodwill — — — Other intangibles — — — Separate account assets — — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ — $ $ — $ Future policy benefits and claims — — — Other policyholder funds — — — Short-term debt — — ) Long-term debt ) ) Income taxes currently payable — — ) Deferred income taxes — — ) Separate account liabilities — — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive loss ) ) ) ) Treasury stock, at cost ) — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Financial Position Principal Principal Principal Life Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ — $ $ — $ Fixed maturities, trading — — — Equity securities, available-for-sale — — — Equity securities, trading — — — Mortgage loans — — — Real estate — — — Policy loans — — — Investment in unconsolidated entities ) Other investments — Cash and cash equivalents ) Accrued investment income — — — Premiums due and other receivables — ) Deferred acquisition costs — — — Property and equipment — — — Goodwill — — — Other intangibles — — — Separate account assets — — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ — $ $ — $ Future policy benefits and claims — — — Other policyholder funds — — — Short-term debt — — ) Long-term debt ) Income taxes currently payable — ) Deferred income taxes — — ) Separate account liabilities — — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive loss ) ) ) ) Treasury stock, at cost ) — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Principal Life Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ — $ $ — $ Fees and other revenues — ) Net investment income Net realized capital gains (losses), excluding impairment losses on available-for-sale securities — ) Net other-than-temporary impairment losses on available-for-sale securities — — ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to other comprehensive income — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Benefits, claims and settlement expenses — — — Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) Income taxes (benefits) ) ) — Equity in the net income of subsidiaries — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Principal Life Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ — $ $ — $ Fees and other revenues — ) Net investment income Net realized capital losses, excluding impairment losses on available-for-sale securities — ) ) — ) Net other-than-temporary impairment losses on available-for-sale securities — — ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified from other comprehensive income — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital losses — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Benefits, claims and settlement expenses — — — Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) Income taxes (benefits) ) ) — Equity in the net income of subsidiaries — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — Excess of redemption value over carrying value of preferred shares redeemed — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive loss ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Principal Life Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ — $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains, excluding impairment losses on available-for-sale securities — ) Net other-than-temporary impairment recoveries on available-for-sale securities — — — Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified from other comprehensive income — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — — — Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) ) Income taxes (benefits) ) ) — Equity in the net income of subsidiaries — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income (loss) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Principal Life Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — — ) — ) Sales — — — Maturities — — — Mortgage loans acquired or originated — — ) — ) Mortgage loans sold or repaid — — — Real estate acquired — — ) — ) Net purchases of property and equipment ) — ) — ) Dividends and returns of capital received from unconsolidated entities — ) — Net change in other investments ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — — ) — ) Excess tax benefits from share-based payment arrangements — — Purchase of subsidiary shares from noncontrolling interest — — ) — ) Dividends to common stockholders ) — — — ) Issuance of long-term debt ) Principal repayments of long-term debt ) ) ) ) Net repayments of short-term borrowings — — ) ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — — Investment contract withdrawals — — ) — ) Net increase in banking operation deposits — — — Other — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) financing activities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Principal Life Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — — ) — ) Sales — — — Maturities — — — Mortgage loans acquired or originated — — ) — ) Mortgage loans sold or repaid — — — Real estate acquired — — ) — ) Net purchases of property and equipment — — ) — ) Purchase of interests in subsidiaries, net of cash acquired — — ) — ) Dividends and returns of capital received from unconsolidated entities — ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — — ) — ) Excess tax benefits from share-based payment arrangements — — Purchase of subsidiary shares from noncontrolling interest — — ) — ) Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Preferred stock redemption ) — — — ) Issuance of long-term debt ) Principal repayments of long-term debt — — ) ) Net proceeds from short-term borrowings — — Dividends and capital paid to parent — ) ) — Investment contract deposits — — — Investment contract withdrawals — — ) — ) Net increase in banking operation deposits — — — Other — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Principal Life Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ ) $ $ ) $ Investing activities Available-for-sale securities: Purchases — — ) — ) Sales — — — Maturities — — — Mortgage loans acquired or originated — — ) — ) Mortgage loans sold or repaid — — — Real estate acquired — — ) — ) Net purchases of property and equipment — — ) — ) Dividends and returns of capital received from unconsolidated entities — ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — — ) — ) Excess tax benefits from share-based payment arrangements — — Purchase of subsidiary shares from noncontrolling interest — — ) — ) Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Issuance of long-term debt — — — Principal repayments of long-term debt — — ) — ) Net repayments of short-term borrowings — — ) ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — — Investment contract withdrawals — — ) — ) Net increase in banking operation deposits — — — Other — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Schedule I - Summary of Investm

Schedule I - Summary of Investments - Other Than Investments in Related Parties	12 Months Ended
	Dec. 31, 2016
Schedule I - Summary of Investments - Other Than Investments in Related Parties
Schedule I - Summary of Investments - Other Than Investments in Related Parties	Schedule I — Summary of Investments — Other Than Investments in Related Parties Type of Investment Cost Fair Amount as (in millions) Fixed maturities, available-for-sale: U.S. Treasury securities and obligations of U.S. government corporations and agencies $ $ $ States, municipalities and political subdivisions Foreign governments Public utilities Redeemable preferred stock All other corporate bonds Residential mortgage-backed securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale Fixed maturities, trading Equity securities, available-for-sale: Banks, trust and insurance companies Industrial, miscellaneous and all other Non-redeemable preferred stock ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale Equity securities, trading Mortgage loans XXXX Real estate, net: Real estate acquired in satisfaction of debt XXXX Other real estate XXXX Policy loans XXXX Other investments XXXX ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments $ XXXX $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Schedule II - Condensed Financi

Schedule II - Condensed Financial Information of Registrant (Parent Only)	12 Months Ended
	Dec. 31, 2016
Schedule II - Condensed Financial Information of Registrant (Parent Only)
Schedule II - Condensed Financial Information of Registrant (Parent Only)	Schedule II — Condensed Financial Information of Registrant (Parent Only) December 31, 2016 2015 (in millions) Assets Cash and cash equivalents $ $ Other investments Income taxes receivable Deferred income taxes Amounts receivable from subsidiaries Other assets Investment in subsidiaries ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Long-term debt $ $ Accrued investment payable Pension liability Other liabilities — ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities Stockholders' equity Common stock, par value $.01 per share — 2,500 million shares authorized, 469.2 million and 466.2 million shares issued, and 287.7 million and 291.4 million shares outstanding in 2016 and 2015 Additional paid-in capital Retained earnings Accumulated other comprehensive loss ) ) Treasury stock, at cost (181.5 million and 174.8 million shares in 2016 and 2015) ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to Principal Financial Group, Inc. ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ See accompanying notes. Statements of Operations For the year ended 2016 2015 2014 (in millions) Revenues Net investment income $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Other operating costs and expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Losses before income taxes ) ) ) Income tax benefits ) ) ) Equity in the net income of subsidiaries ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to Principal Financial Group, Inc. Less: Preferred stock dividends — Excess of redemption value over carrying value of preferred shares redeemed — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ See accompanying notes. Statements of Cash Flows For the year ended 2016 2015 2014 (in millions) Operating activities Net income $ $ $ Adjustments to reconcile net income to net cash used in operating activities: Equity in the net income of subsidiaries ) ) ) Current and deferred income tax benefits ) ) ) Stock-based compensation Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in operating activities ) ) ) Investing activities Net purchases of property and equipment ) — — Net change in other investments ) Dividends and returns of capital received from unconsolidated entity ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by investing activities Financing activities Issuance of common stock Acquisition of treasury stock ) ) ) Excess tax benefits from share-based payment arrangements Dividends to common stockholders ) ) ) Dividends to preferred stockholders — ) ) Preferred stock redemption — ) — Principal repayments of long-term debt ) — — Issuance of long-term debt — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase in cash and cash equivalents Cash and cash equivalents at beginning of year ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ See accompanying notes. (1) Basis of Presentation The accompanying condensed financial information should be read in conjunction with the consolidated financial statements and notes thereto of Principal Financial Group, Inc. In the parent company only financial statements, our investments in subsidiaries are stated as cost plus equity in undistributed earnings of subsidiaries. During November 2016, the parent company became the sponsor of the defined contribution plans and deferred compensation plans discussed in Item 8. "Financial Statements and Supplementary Data, Notes to Consolidated Financial Statements, Note 11, Employee and Agent Benefits." Prior to November 2016, Principal Life Insurance Company, an indirect wholly owned subsidiary of the parent company, was the sponsor of these plans. (2) Dividends and Returns of Capital Received from (Contributions to) Unconsolidated Entity The parent company received cash dividends and returns of capital totaling $1,295.3 million, $685.5 million and $917.7 million from subsidiaries in 2016, 2015 and 2014, respectively. (3) Supplemental Disclosures of Non-Cash Investing Activity The parent company's assumption of the deferred income tax asset and net plan assets associated with the defined contribution plans and deferred compensation plans previously sponsored by Principal Life Insurance Company resulted in a non-cash increase in the parent company's investment in subsidiary of $74.6 million in 2016.

Schedule III - Supplementary In

Schedule III - Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2016
Schedule III - Supplementary Insurance Information
Schedule III - Supplementary Insurance Information	Schedule III — Supplementary Insurance Information Segment Deferred Future policy Contractholder (in millions) 2016: Retirement and Income Solutions $ $ $ Principal Global Investors — — — Principal International U.S. Insurance Solutions Corporate — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2015: Retirement and Income Solutions $ $ $ Principal Global Investors — — — Principal International U.S. Insurance Solutions Corporate — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Schedule III — Supplementary Insurance Information — (continued) Segment Premiums and Net Benefits, claims Amortization of Other (in millions) 2016: Retirement and Income Solutions $ $ $ $ $ Principal Global Investors — — — Principal International U.S. Insurance Solutions Corporate — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2015: Retirement and Income Solutions $ $ $ $ $ Principal Global Investors — — — Principal International U.S. Insurance Solutions Corporate — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014: Retirement and Income Solutions $ $ $ $ $ Principal Global Investors — — — Principal International U.S. Insurance Solutions Corporate ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Allocations of net investment income and certain operating expenses are based on a number of assumptions and estimates, and reported operating results would change by segment if different methods were applied.

Schedule IV - Reinsurance

Schedule IV - Reinsurance	12 Months Ended
	Dec. 31, 2016
Schedule IV - Reinsurance
Schedule IV - Reinsurance	Schedule IV — Reinsurance Gross Ceded to Assumed Net amount Percentage ($ in millions) 2016: Life insurance in force $ $ $ $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Premiums: Life insurance and annuities $ $ $ $ — % Accident and health insurance — — % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ — % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2015: Life insurance in force $ $ $ $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Premiums: Life insurance and annuities $ $ $ $ — % Accident and health insurance — — % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ — % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014: Life insurance in force $ $ $ $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Premiums: Life insurance and annuities $ $ $ $ % Accident and health insurance — — % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Nature of Operations and Sign32

Nature of Operations and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Nature of Operations and Significant Accounting Policies
Cash and Cash Equivalents - Policy	Cash and Cash Equivalents Cash and cash equivalents include cash on hand, money market instruments and other debt issues with a maturity date of three months or less when purchased.
Investments - Policy	Investments Fixed maturities include bonds, asset-backed securities ("ABS"), redeemable preferred stock and certain non-redeemable preferred securities. Equity securities include mutual funds, common stock, non-redeemable preferred stock and required regulatory investments. We classify fixed maturities and equity securities as either available-for-sale or trading at the time of the purchase and, accordingly, carry them at fair value. See Note 14, Fair Value Measurements, for methodologies related to the determination of fair value. Unrealized gains and losses related to available-for-sale securities, excluding those in fair value hedging relationships, are reflected in stockholders' equity, net of adjustments associated with DAC and related actuarial balances, derivatives in cash flow hedge relationships and applicable income taxes. Unrealized gains and losses related to hedged portions of available-for-sale securities in fair value hedging relationships and mark-to-market adjustments on certain trading securities are reflected in net realized capital gains (losses). Mark-to-market adjustments related to certain securities carried at fair value with an investment objective to realize economic value through mark-to-market changes are reflected in net investment income. The cost of fixed maturities is adjusted for amortization of premiums and accrual of discounts, both computed using the interest method. The cost of fixed maturities and equity securities classified as available-for-sale is adjusted for declines in value that are other than temporary. Impairments in value deemed to be other than temporary are primarily reported in net income as a component of net realized capital gains (losses), with noncredit impairment losses for certain fixed maturities, available-for-sale reported in other comprehensive income ("OCI"). Interest income, as well as prepayment fees and the amortization of the related premium or discount, is reported in net investment income. For loan-backed and structured securities, we recognize income using a constant effective yield based on currently anticipated cash flows. Real estate investments are reported at cost less accumulated depreciation. The initial cost bases of properties acquired through loan foreclosures are the lower of the fair market values of the properties at the time of foreclosure or the outstanding loan balance. Buildings and land improvements are generally depreciated on the straight-line method over the estimated useful life of improvements and tenant improvement costs are depreciated on the straight-line method over the term of the related lease. We recognize impairment losses for properties when indicators of impairment are present and a property's expected undiscounted cash flows are not sufficient to recover the property's carrying value. In such cases, the cost basis of the properties are reduced to fair value. Real estate expected to be disposed is carried at the lower of cost or fair value, less cost to sell, with valuation allowances established accordingly and depreciation no longer recognized. The carrying amount of real estate held for sale was $130.7 million and $169.7 million as of December 31, 2016 and 2015, respectively. Any impairment losses and any changes in valuation allowances are reported in net income. Commercial and residential mortgage loans are generally reported at cost adjusted for amortization of premiums and accrual of discounts, computed using the interest method and net of valuation allowances. Interest income is accrued on the principal amount of the loan based on the loan's contractual interest rate. Interest income, as well as prepayment of fees and the amortization of the related premium or discount, is reported in net investment income. Any changes in the valuation allowances are reported in net income as net realized capital gains (losses). We measure impairment based upon the difference between carrying value and estimated value less cost to sell. Estimated value is based on either the present value of expected cash flows discounted at the loan's effective interest rate, the loan's observable market price or the fair value of the collateral. If foreclosure is probable, the measurement of any valuation allowance is based upon the fair value of the collateral. Net realized capital gains and losses on sales of investments are determined on the basis of specific identification. In general, in addition to realized capital gains and losses on investment sales and periodic settlements on derivatives not designated as hedges, we report gains and losses related to the following in net realized capital gains (losses): other-than-temporary impairments of securities and subsequent realized recoveries, mark-to-market adjustments on certain trading securities, mark-to-market adjustments on sponsored investment funds, fair value hedge and cash flow hedge ineffectiveness, mark-to-market adjustments on derivatives not designated as hedges, changes in the mortgage loan valuation allowance provision, impairments of real estate held for investment and impairments of equity method investments. Investment gains and losses on sales of certain real estate held for sale due to investment strategy and mark-to-market adjustments on certain securities carried at fair value with an investment objective to realize economic value through mark-to-market changes are reported as net investment income and are excluded from net realized capital gains (losses). Policy loans and certain other investments are reported at cost. Interests in unconsolidated entities, joint ventures and partnerships are generally accounted for using the equity method. We have other investments reported at fair value or for which the fair value option has been elected. See Note 14, Fair Value Measurements, for detail on these investments.
Derivatives - Policy	Derivatives Overview Derivatives are financial instruments whose values are derived from interest rates, foreign exchange rates, financial indices or the values of securities. Derivatives generally used by us include interest rate swaps, interest rate options, swaptions, currency swaps, currency forwards, equity options, futures, credit default swaps and total return swaps. Derivative positions are either assets or liabilities in the consolidated statements of financial position and are measured at fair value, generally by obtaining quoted market prices or through the use of pricing models. See Note 14, Fair Value Measurements, for policies related to the determination of fair value. Fair values can be affected by changes in interest rates, foreign exchange rates, financial indices, values of securities, credit spreads, and market volatility and liquidity. Accounting and Financial Statement Presentation We designate derivatives as either: (a) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, including those denominated in a foreign currency ("fair value hedge"); (b) a hedge of a forecasted transaction or the exposure to variability of cash flows to be received or paid related to a recognized asset or liability, including those denominated in a foreign currency ("cash flow hedge"); (c) a hedge of a net investment in a foreign operation or (d) a derivative not designated as a hedging instrument. Our accounting for the ongoing changes in fair value of a derivative depends on the intended use of the derivative and the designation, as described above, and is determined when the derivative contract is entered into or at the time of redesignation. Hedge accounting is used for derivatives that are specifically designated in advance as hedges and that reduce our exposure to an indicated risk by having a high correlation between changes in the value of the derivatives and the items being hedged at both the inception of the hedge and throughout the hedge period. Fair Value Hedges. When a derivative is designated as a fair value hedge and is determined to be highly effective, changes in its fair value, along with changes in the fair value of the hedged asset, liability or firm commitment attributable to the hedged risk, are reported in net realized capital gains (losses). Any difference between the net change in fair value of the derivative and the hedged item represents hedge ineffectiveness. Cash Flow Hedges. When a derivative is designated as a cash flow hedge and is determined to be highly effective, changes in its fair value are recorded as a component of OCI. Any hedge ineffectiveness is recorded immediately in net income. At the time the variability of cash flows being hedged impacts net income, the related portion of deferred gains or losses on the derivative instrument is reclassified and reported in net income. Net Investment in a Foreign Operation Hedge. When a derivative is used as a hedge of a net investment in a foreign operation, its change in fair value, to the extent effective as a hedge, is recorded as a component of OCI. Any hedge ineffectiveness is recorded immediately in net income. If the foreign operation is sold or upon complete or substantially complete liquidation, the deferred gains or losses on the derivative instrument are reclassified into net income. Non-Hedge Derivatives. If a derivative does not qualify or is not designated for hedge accounting, all changes in fair value are reported in net income without considering the changes in the fair value of the economically associated assets or liabilities. Hedge Documentation and Effectiveness Testing. At inception, we formally document all relationships between hedging instruments and hedged items, as well as our risk management objective and strategy for undertaking various hedge transactions. This process includes associating all derivatives designated as fair value or cash flow hedges with specific assets or liabilities on the consolidated statements of financial position or with specific firm commitments or forecasted transactions. Effectiveness of the hedge is formally assessed at inception and throughout the life of the hedging relationship. Even if a derivative is highly effective and qualifies for hedge accounting treatment, the hedge might have some ineffectiveness. We use qualitative and quantitative methods to assess hedge effectiveness. Qualitative methods may include monitoring changes to terms and conditions and counterparty credit ratings. Quantitative methods may include statistical tests including regression analysis and minimum variance and dollar offset techniques. Termination of Hedge Accounting. We prospectively discontinue hedge accounting when (1) the criteria to qualify for hedge accounting is no longer met, e.g., a derivative is determined to no longer be highly effective in offsetting the change in fair value or cash flows of a hedged item; (2) the derivative expires, is sold, terminated or exercised or (3) we remove the designation of the derivative being the hedging instrument for a fair value or cash flow hedge. If it is determined that a derivative no longer qualifies as an effective hedge, the derivative will continue to be carried on the consolidated statements of financial position at its fair value, with changes in fair value recognized prospectively in net realized capital gains (losses). The asset or liability under a fair value hedge will no longer be adjusted for changes in fair value pursuant to hedging rules and the existing basis adjustment is amortized to the consolidated statements of operations line associated with the asset or liability. The component of accumulated other comprehensive income ("AOCI") related to discontinued cash flow hedges that are no longer highly effective is amortized to the consolidated statements of operations consistent with the net income impacts of the original hedged cash flows. If a cash flow hedge is discontinued because it is probable the hedged forecasted transaction will not occur, the deferred gain or loss is immediately reclassified from AOCI into net income. Embedded Derivatives. We purchase and issue certain financial instruments and products that contain a derivative that is embedded in the financial instrument or product. We assess whether this embedded derivative is clearly and closely related to the asset or liability that serves as its host contract. If we deem that the embedded derivative's terms are not clearly and closely related to the host contract, and a separate instrument with the same terms would qualify as a derivative instrument, the derivative is bifurcated from that contract and held at fair value on the consolidated statements of financial position, with changes in fair value reported in net income.
Contractholder and Policyholder Liabilities - Policy	Contractholder and Policyholder Liabilities Contractholder and policyholder liabilities (contractholder funds, future policy benefits and claims and other policyholder funds) include reserves for investment contracts, individual and group annuities that provide periodic income payments, universal life, term life insurance, participating traditional individual life insurance, group life insurance, health insurance and disability income policies, as well as a provision for dividends on participating policies. Investment contracts are contractholders' funds on deposit with us and generally include reserves for pension and annuity contracts. Reserves on investment contracts are equal to the cumulative deposits less any applicable charges and withdrawals plus credited interest. Reserves for universal life insurance contracts are equal to cumulative deposits less charges plus credited interest, which represents the account balances that accrue to the benefit of the policyholders. We hold additional reserves on certain long-duration contracts where benefit features result in gains in early years followed by losses in later years, universal life/variable universal life contracts that contain no lapse guarantee features, or annuities with guaranteed minimum death benefits. Reserves for individual and group annuities that provide periodic income payments, nonparticipating term life insurance and disability income contracts are computed on a basis of assumed investment yield, mortality, morbidity and expenses, including a provision for adverse deviation, which generally varies by plan, year of issue and policy duration. Investment yield is based on our experience. Mortality, morbidity and withdrawal rate assumptions are based on our experience and are periodically reviewed against both industry standards and experience. Reserves for participating life insurance contracts are based on the net level premium reserve for death and endowment policy benefits. This net level premium reserve is calculated based on dividend fund interest rates and mortality rates guaranteed in calculating the cash surrender values described in the contract. Participating business represented approximately 8%, 9% and 11% of our life insurance in force and 33%, 36% and 40% of the number of life insurance policies in force as of December 31, 2016, 2015 and 2014, respectively. Participating business represented approximately 31%, 36% and 40% of life insurance premiums for the years ended December 31, 2016, 2015 and 2014, respectively. The amount of dividends to policyholders is declared annually by Principal Life's Board of Directors. The amount of dividends to be paid to policyholders is determined after consideration of several factors including interest, mortality, morbidity and other expense experience for the year and judgment as to the appropriate level of statutory surplus to be retained by Principal Life. At the end of the reporting period, Principal Life establishes a dividend liability for the pro rata portion of the dividends expected to be paid on or before the next policy anniversary date. Some of our policies and contracts require payment of fees or other policyholder assessments in advance for services that will be rendered over the estimated lives of the policies and contracts. These payments are established as unearned revenue liabilities upon receipt and included in other policyholder funds in the consolidated statements of financial position. These unearned revenue reserves are amortized to operations over the estimated lives of these policies and contracts in relation to the emergence of estimated gross profits ("EGPs"). The liability for unpaid claims for both long-duration and short-duration contracts is an estimate of the ultimate net cost of reported and unreported losses not yet settled. This liability is estimated using actuarial analyses and case basis evaluations. Although considerable variability is inherent in such estimates, we believe the liability for unpaid claims is adequate. These estimates are continually reviewed and, as adjustments to this liability become necessary, such adjustments are reflected in net income. Our liability for unpaid claims does not include any allocated claim adjustment expenses. We incur claim adjustment expenses for both long-duration and short-duration contracts that cannot be allocated to a specific claim. Our claim adjustment expense liability is estimated using actuarial analyses based on historical trends of expenses and expected claim runout patterns. Short-Duration Contracts We include the following group products in our short-duration insurance contracts disclosures: long-term disability ("LTD"), group life waiver, dental, vision, short-term disability ("STD") and group life. Future policy benefits and claims include reserves for group life and disability insurance that provide periodic income payments. These reserves are computed using assumptions of mortality, morbidity and investment performance. These assumptions are based on our experience, industry results, emerging trends and future expectations. Future policy benefits and claims also include reserves for incurred but unreported group disability, dental, vision and life insurance claims. We recognize claims costs in the period the service was provided to our policyholders. However, claims costs incurred in a particular period are not known with certainty until after we receive, process and pay the claims. We determine the amount of this liability using actuarial methods based on historical claim payment patterns as well as emerging cost trends, where applicable, to determine our estimate of claim liabilities. We have defined claim frequency as follows for each short-duration product: • LTD: Claim frequency is based on submitted reserve claim counts. • Group Life Waiver: Claim frequency is based on submitted reserve claim counts, consistent with LTD. • Dental and Vision: Claim frequency is based on the claim form, which may include one or more procedures. • STD: Claim frequency is based on submitted claims. • Group Life: Claim frequency is based on submitted life claims (lives, not coverages). We did not make any significant changes to our methodologies or assumptions used to calculate the liability for unpaid claims for short-duration contracts during 2016.
Recognition of Premiums and Other Considerations, Fees and Other Revenues and Benefits - Policy	Recognition of Premiums and Other Considerations, Fees and Other Revenues and Benefits Traditional individual life insurance products include those products with fixed and guaranteed premiums and benefits and consist principally of whole life and term life insurance policies. Premiums from these products are recognized as premium revenue when due. Related policy benefits and expenses for individual life products are associated with earned premiums and result in the recognition of profits over the expected term of the policies and contracts. Immediate annuities with life contingencies include products with fixed and guaranteed annuity considerations and benefits and consist principally of group and individual single premium annuities with life contingencies. Annuity considerations from these products are recognized as premium revenue. However, the collection of these annuity considerations does not represent the completion of the earnings process, as we establish annuity reserves using estimates for mortality and investment assumptions, which include provision for adverse deviation as required by U.S. GAAP. We anticipate profits to emerge over the life of the annuity products as we earn investment income, pay benefits and release reserves. Group life and health insurance premiums are generally recorded as premium revenue over the term of the coverage. Certain group contracts contain experience premium refund provisions based on a pre-defined formula that reflects their claim experience. Experience premium refunds reduce revenue over the term of the coverage and are adjusted to reflect current experience. Related policy benefits and expenses for group life and health insurance products are associated with earned premiums and result in the recognition of profits over the term of the policies and contracts. Fees for contracts providing claim processing or other administrative services are recorded as revenue over the period the service is provided. Universal life-type policies are insurance contracts with terms that are not fixed. Amounts received as payments for such contracts are not reported as premium revenues. Revenues for universal life-type insurance contracts consist of policy charges for the cost of insurance, policy initiation and administration, surrender charges and other fees that have been assessed against policy account values and investment income. Policy benefits and claims that are charged to expense include interest credited to contracts and benefit claims incurred in the period in excess of related policy account balances. Investment contracts do not subject us to significant risks arising from policyholder mortality or morbidity and consist primarily of guaranteed investment contracts ("GICs"), funding agreements and certain deferred annuities. Amounts received as payments for investment contracts are established as investment contract liability balances and are not reported as premium revenues. Revenues for investment contracts consist of investment income and policy administration charges. Investment contract benefits that are charged to expense include benefit claims incurred in the period in excess of related investment contract liability balances and interest credited to investment contract liability balances. Fees and other revenues are earned for asset management services provided to retail and institutional clients based largely upon contractual rates applied to the market value of the client's portfolio. Additionally, fees and other revenues are earned for administrative services performed including recordkeeping and reporting services for retirement savings plans. Fees and other revenues received for performance of asset management and administrative services are recognized as revenue when earned, typically when the service is performed. Fees for managing customers' mandatory retirement savings accounts in Chile are collected with each monthly deposit made by our customers. If a customer stops contributing before retirement age, we collect no fees but services are still provided. We recognize revenue from these long-term service contracts as services are performed over the life of the contract.
Deferred Acquisition Costs - Policy	Deferred Acquisition Costs Incremental direct costs of contract acquisition as well as certain costs directly related to acquisition activities (underwriting, policy issuance and processing, medical and inspection and sales force contract selling) for the successful acquisition of new and renewal insurance policies and investment contract business are capitalized to the extent recoverable. Commissions and other incremental direct costs for the acquisition of long-term service contracts are also capitalized to the extent recoverable. Maintenance costs and acquisition costs that are not deferrable are charged to net income as incurred. DAC for universal life-type insurance contracts and certain investment contracts are amortized over the lives of the contracts in relation to EGPs or, in certain circumstances, estimated gross revenues. This amortization is adjusted in the current period when EGPs or estimated gross revenues are revised. For individual variable life insurance, individual variable annuities and group annuities that have separate account U.S. equity investment options, we utilize a mean reversion methodology (reversion to the mean assumption), a common industry practice, to determine the future domestic equity market growth rate assumption used for the calculation of EGPs. DAC for participating life insurance policies are amortized in proportion to estimated gross margins. DAC for non-participating term life insurance and individual disability policies are amortized over the premium-paying period of the related policies using assumptions consistent with those used in computing policyholder liabilities. DAC on insurance policies and investment contracts are subject to recoverability testing at the time of policy issue and loss recognition testing on an annual basis, or when an event occurs that may warrant loss recognition. If loss recognition or impairment is necessary, DAC would be written off to the extent it is determined that future policy premiums and investment income or gross profits are not adequate to cover related losses and expenses. DAC for long-term service contracts are amortized in proportion to the revenue recognized or straight-line if no pattern of revenue recognition can be reasonably predicted. We amortize capitalized costs of long-term service contracts on a straight-line basis, reflecting lapses as they are incurred, over the expected contract life.
Deferred Acquisition Costs on Internal Replacements - Policy	Deferred Acquisition Costs on Internal Replacements All insurance and investment contract modifications and replacements are reviewed to determine if the internal replacement results in a substantially changed contract. If so, the acquisition costs, sales inducements and unearned revenue associated with the new contract are deferred and amortized over the lifetime of the new contract. In addition, the existing DAC, sales inducement costs and unearned revenue balances associated with the replaced contract are written off. If an internal replacement results in a substantially unchanged contract, the acquisition costs, sales inducements and unearned revenue associated with the new contract are immediately recognized in the period incurred. In addition, the existing DAC, sales inducement costs or unearned revenue balance associated with the replaced contract is not written off, but instead is carried over to the new contract.
Long-Term Debt - Policy	Long-Term Debt Long-term debt includes notes payable, nonrecourse mortgages and other debt with a maturity date greater than one year at the date of issuance. Current maturities of long-term debt are classified as long-term debt in our consolidated statements of financial position.
Reinsurance - Policy	Reinsurance We enter into reinsurance agreements with other companies in the normal course of business in order to limit losses and minimize exposure to significant risks. We may assume reinsurance from or cede reinsurance to other companies. Assets and liabilities related to reinsurance ceded are reported on a gross basis. Premiums and expenses are reported net of reinsurance ceded. The cost of reinsurance related to long-duration contracts is accounted for over the life of the underlying reinsured policies using assumptions consistent with those used to account for the underlying policies. We are contingently liable with respect to reinsurance ceded to other companies in the event the reinsurer is unable to meet the obligations it has assumed. As of December 31, 2016 and 2015, we had $412.8 million and $397.5 million of net ceded reinsurance recoverables related to claims that have been received, respectively. As of December 31, 2016 and 2015, $390.5 million, or 95%, and $379.4 million, or 95%, were with our five largest ceded reinsurers, respectively. Our total amount recoverable from reinsurers includes net ceded reinsurance recoverables related to claims that have been received and reserves ceded to reinsurers; however, it does not reflect potentially offsetting impacts of collateral. As of December 31, 2016 and 2015, the total amount recoverable from reinsurers was $837.1 million and $857.3 million, respectively. The effects of reinsurance on premiums and other considerations and policy and contract benefits were as follows: For the year ended 2016 2015 2014 (in millions) Premiums and other considerations: Direct $ $ $ Assumed Ceded ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net premiums and other considerations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefits, claims and settlement expenses: Direct $ $ $ Assumed Ceded ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net benefits, claims and settlement expenses $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Separate Accounts - Policy	Separate Accounts The separate accounts are legally segregated and are not subject to the claims that arise out of any of our other business. The client, rather than us, directs the investments and bears the investment risk of these funds. The separate account assets represent the fair value of funds that are separately administered by us for contracts with equity, real estate and fixed income investments and are presented as a summary total within the consolidated statements of financial position. An equivalent amount is reported as separate account liabilities, which represent the obligation to return the monies to the client. We receive fees for mortality, withdrawal and expense risks, as well as administrative, maintenance and investment advisory services that are included in the consolidated statements of operations. Net deposits, net investment income and realized and unrealized capital gains and losses of the separate accounts are not reflected in the consolidated statements of operations. Separate account assets and separate account liabilities include certain international retirement accumulation products where the segregated funds and associated obligation to the client are consolidated within our financial statements. We have determined that summary totals are the most meaningful presentation for these funds. As of December 31, 2016 and December 31, 2015, the separate accounts included a separate account valued at $158.4 million and $158.2 million, respectively, which primarily included shares of our stock that were allocated and issued to eligible participants of qualified employee benefit plans administered by us as part of the policy credits issued under our 2001 demutualization. These shares are included in both basic and diluted earnings per share calculations. In the consolidated statements of financial position, the separate account shares are recorded at fair value and are reported as separate account assets with a corresponding separate account liability to eligible participants of the qualified plan. Changes in fair value of the separate account shares are reflected in both the separate account assets and separate account liabilities and do not impact our results of operations.
Income Taxes - Policy	Income Taxes We file a U.S. consolidated income tax return that includes all of our qualifying subsidiaries. In addition, we file income tax returns in all states and foreign jurisdictions in which we conduct business. Our policy of allocating income tax expenses and benefits to companies in the group is generally based upon pro rata contribution of taxable income or operating losses. We are taxed at corporate rates on taxable income based on existing tax laws. Current income taxes are charged or credited to net income based upon amounts estimated to be payable or recoverable as a result of taxable operations for the current year. Deferred income taxes are provided for the tax effect of temporary differences in the financial reporting and income tax bases of assets and liabilities, net operating loss carryforwards and tax credit carryforwards using enacted income tax rates and laws. The effect on deferred income tax assets and deferred income tax liabilities of a change in tax rates is recognized in net income in the period in which the change is enacted.
Foreign Exchange - Policy	Foreign Exchange Assets and liabilities of our foreign subsidiaries and affiliates denominated in non-U.S. dollars, where the U.S. dollar is not the functional currency, are translated into U.S. dollar equivalents at the year-end spot foreign exchange rates. Resulting translation adjustments are reported as a component of stockholders' equity, along with any related hedge and tax effects. Revenues and expenses for these entities are translated at the average exchange rates. Revenue, expense and other foreign currency transaction and translation adjustments that affect cash flows are reported in net income, along with related hedge and tax effects.
Goodwill and Other Intangibles - Policy	Goodwill and Other Intangibles Goodwill and other intangible assets include the cost of acquired subsidiaries in excess of the fair value of the net tangible assets recorded in connection with acquisitions. Goodwill and indefinite-lived intangible assets are not amortized. Rather, they are tested for impairment during the third quarter each year, or more frequently if events or changes in circumstances indicate that the asset might be impaired. Goodwill is tested at the reporting unit level, which is a business one level below the operating segment, if financial information is prepared and regularly reviewed by management at that level. Once goodwill has been assigned to a reporting unit, it is no longer associated with a particular acquisition; therefore, all of the activities within a reporting unit, whether acquired or organically grown, are available to support the goodwill value. Impairment testing for indefinite-lived intangible assets consists of a comparison of the fair value of the intangible asset with its carrying value. Intangible assets with a finite useful life are amortized as related benefits emerge and are reviewed periodically for indicators of impairment in value. If facts and circumstances suggest possible impairment, the sum of the estimated undiscounted future cash flows expected to result from the use of the asset is compared to the current carrying value of the asset. If the undiscounted future cash flows are less than the carrying value, an impairment loss is recognized for the excess of the carrying amount of assets over their fair value.
Earnings Per Common Share - Policy	Earnings Per Common Share Basic earnings per common share is calculated by dividing income available to common stockholders by the weighted-average number of common shares outstanding for the period and excludes the dilutive effect of equity awards. Diluted earnings per common share reflects the potential dilution that could occur if dilutive securities, such as options and non-vested stock grants, were exercised or resulted in the issuance of common stock.

Nature of Operations and Sign33

Nature of Operations and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Nature of Operations and Significant Accounting Policies
Effects of Reinsurance on Premiums and Other Considerations and Policy and Contract Benefits (Table)	For the year ended 2016 2015 2014 (in millions) Premiums and other considerations: Direct $ $ $ Assumed Ceded ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net premiums and other considerations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefits, claims and settlement expenses: Direct $ $ $ Assumed Ceded ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net benefits, claims and settlement expenses $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Goodwill and Other Intangible34

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill and Other Intangible Assets
Goodwill (Table)	Retirement Principal Principal U.S. Corporate Consolidated (in millions) Balance as of January 1, 2015 $ $ $ $ $ — $ Goodwill from acquisitions — — — Foreign currency — ) ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of December 31, 2015 — Foreign currency — ) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of December 31, 2016 $ $ $ $ $ — $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Finite Lived Intangible Assets (Table)	December 31, 2016 2015 (in millions) Gross carrying value $ $ Accumulated amortization ​ ​ ​ ​ ​ ​ ​ ​ Net carrying value $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Other Finite Lived Intangible Assets Estimated Amortization Expense (Table)	As of December 31, 2016, the estimated amortization expense for the next five years is as follows (in millions): Year ending December 31: 2017 $ 2018 2019 2020 2021

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2016
Variable Interest Entities
Carrying Amounts of Assets and Liabilities of Consolidated Variable Interest Entities (Table)	December 31, 2016 December 31, 2015 Total Total Total Total (in millions) Grantor trusts (1) $ $ $ $ Collateralized private investment vehicles (2) CMBS — — Mandatory retirement savings funds (3) Real estate (4) Sponsored investment funds (5) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The assets of grantor trusts are primarily fixed maturities, available-for-sale. The liabilities are primarily other liabilities that reflect an embedded derivative of the forecasted transaction to deliver the underlying securities. (2) The assets of the collateralized private investment vehicles are primarily fixed maturities, trading. The liabilities include derivative liabilities and an obligation to redeem notes at maturity or termination of the trusts, which are reported in other liabilities. (3) The assets of the mandatory retirement savings funds include separate account assets and equity securities, trading. The liabilities include separate account liabilities and contractholder funds. (4) The assets of the real estate VIEs primarily include real estate, other investments and cash. Liabilities primarily include other liabilities. Liabilities also included long-term debt as of December 31, 2015. (5) The assets of sponsored investment funds are primarily fixed maturities and equity securities reported in other investments and cash. The consolidated statements of financial position included a $58.8 million redeemable noncontrolling interest for sponsored investment funds as of December 31, 2016.
Asset Carrying Value and Maximum Loss Exposure of Unconsolidated Variable Interest Entities (Table)	Asset carrying value Maximum exposure to (in millions) December 31, 2016 Fixed maturities, available-for-sale: Corporate $ $ Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations Fixed maturities, trading: Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Equity securities, trading Other investments: Other limited partnership and fund interests December 31, 2015 Fixed maturities, available-for-sale: Corporate $ $ Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations Fixed maturities, trading: Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other investments: Other limited partnership and fund interests (1) Our risk of loss is limited to our initial investment measured at amortized cost for fixed maturities, available-for-sale. Our risk of loss is limited to our investment measured at fair value for our fixed maturities, trading and equity securities, trading. Our risk of loss is limited to our carrying value plus any unfunded commitments and/or guarantees for our other investments. Unfunded commitments are not liabilities on our consolidated statements of financial position because we are only required to fund additional equity when called upon to do so by the general partner or investment manager.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Investments
Fixed Maturities and Equity Securities Available-for-Sale (Table)	Amortized Gross Gross Fair value Other-than- (in millions) December 31, 2016 Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ $ — Non-U.S. governments — States and political subdivisions Corporate Residential mortgage-backed pass-through securities — Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ $ — Non-U.S. governments — States and political subdivisions — Corporate Residential mortgage-backed pass-through securities — Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Excludes $120.9 million and $131.5 million as of December 31, 2016 and December 31, 2015, respectively, of net unrealized gains on impaired fixed maturities, available-for-sale related to changes in fair value subsequent to the impairment date, which are included in gross unrealized gains and gross unrealized losses.
Fixed Maturities Available-for-Sale by Contractual Maturity (Table)	Amortized Fair (in millions) Due in one year or less $ $ Due after one year through five years Due after five years through ten years Due after ten years ​ ​ ​ ​ ​ ​ ​ ​ Subtotal Mortgage-backed and other asset-backed securities ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Net Investment Income (Table)	For the year ended 2016 2015 2014 (in millions) Fixed maturities, available-for-sale $ $ $ Fixed maturities, trading Equity securities, available-for-sale Equity securities, trading Mortgage loans Real estate Policy loans Cash and cash equivalents Derivatives (1) ) ) ) Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Investment expenses ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net investment income $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Relates to periodic settlements of derivatives used in fair value and cash flow hedges of fixed maturities, available-for-sale. See Note 5, Derivative Financial Instruments, for further details.
Net Realized Capital Gains and Losses (Table)	For the year ended 2016 2015 2014 (in millions) Fixed maturities, available-for-sale: Gross gains $ $ $ Gross losses ) ) ) Net impairment losses ) ) ) Hedging, net ) ) ) Fixed maturities, trading ) Equity securities, available-for-sale: Gross gains — Gross losses — ) ) Net impairment (losses) recoveries ) Equity securities, trading ) Mortgage loans ) ) Derivatives Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Other-Than-Temporary Impairment Losses, Net of Recoveries (Table)	For the year ended 2016 2015 2014 (in millions) Fixed maturities, available-for-sale $ ) $ ) $ Equity securities, available-for-sale ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other-than-temporary impairment losses, net of recoveries from the sale of previously impaired securities ) ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) OCI (1) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Represents the net impact of (a) gains resulting from reclassification of noncredit impairment losses for fixed maturities with bifurcated OTTI from net realized capital gains (losses) to OCI and (b) losses resulting from reclassification of previously recognized noncredit impairment losses from OCI to net realized capital gains (losses) for fixed maturities with bifurcated OTTI that had additional credit losses or fixed maturities that previously had bifurcated OTTI that have now been sold or are intended to be sold.
Other-Than-Temporary Impairment, Credit Losses Recognized in Earnings (Table)	For the year ended 2016 2015 2014 (in millions) Beginning balance $ ) $ ) $ ) Credit losses for which an other-than-temporary impairment was not previously recognized ) ) ) Credit losses for which an other-than-temporary impairment was previously recognized ) ) ) Reduction for credit losses previously recognized on fixed maturities now sold, paid down or intended to be sold Net reduction for positive changes in cash flows expected to be collected and amortization (1) Foreign currency translation adjustment ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Amounts are recognized in net investment income.
Gross Unrealized Losses for Fixed Maturities and Equity Securities (Table)	December 31, 2016 Less than twelve Greater than or Total Fair Gross Fair Gross Fair Gross (in millions) Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ — $ $ Non-U.S. governments States and political subdivisions Corporate Residential mortgage-backed pass-through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Less than twelve Greater than or Total Fair Gross Fair Gross Fair Gross (in millions) Fixed maturities, available-for-sale: U.S. government and agencies $ $ $ $ $ $ Non-U.S. governments States and political subdivisions Corporate Residential mortgage-backed pass- through securities Commercial mortgage-backed securities Collateralized debt obligations Other debt obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total equity securities, available-for-sale $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Net Unrealized Gains and Losses on Available-for-Sale Securities and Derivative Instruments (Table)	December 31, 2016 December 31, 2015 (in millions) Net unrealized gains on fixed maturities, available-for-sale (1) $ $ Noncredit component of impairment losses on fixed maturities, available-for-sale ) ) Net unrealized losses on equity securities, available-for-sale ) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ) Net unrealized gains on derivative instruments Net unrealized gains on equity method subsidiaries and noncontrolling interest adjustments Provision for deferred income taxes ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on available-for-sale securities and derivative instruments $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Excludes net unrealized gains (losses) on fixed maturities, available-for-sale included in fair value hedging relationships.
Mortgage Loans (Table)	December 31, 2016 December 31, 2015 (in millions) Commercial mortgage loans $ $ Residential mortgage loans ​ ​ ​ ​ ​ ​ ​ ​ Total amortized cost Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total carrying value $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Mortgage Loans Purchased and Sold (Table)	For the year ended 2016 2015 2014 (in millions) Commercial mortgage loans: Purchased $ $ $ Sold Residential mortgage loans: Purchased Sold
Commercial Mortgage Loans by Geographic Distribution and Property Type Distribution (Table)	December 31, 2016 December 31, 2015 Amortized Percent Amortized Percent ($ in millions) Geographic distribution New England $ % $ % Middle Atlantic East North Central West North Central South Atlantic East South Central West South Central Mountain Pacific International ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ % $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Property type distribution Office $ % $ % Retail Industrial Apartments Hotel Mixed use/other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ % $ % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Commercial Mortgage Loan Portfolio by Credit Risk (Table)	December 31, 2016 Brick and mortar CTL Total (in millions) A– and above $ $ $ BBB+ thru BBB– BB+ thru BB– — B+ and below ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Brick and mortar CTL Total (in millions) A– and above $ $ $ BBB+ thru BBB– BB+ thru BB– B+ and below ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Performing and Non-Performing Residential Mortgage Loans (Table)	December 31, 2016 Home equity First liens Total (in millions) Performing $ $ $ Non-performing ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Home equity First liens Total (in millions) Performing $ $ $ Non-performing ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Non-Accrual Mortgage Loans (Table)	December 31, 2016 December 31, 2015 (in millions) Residential: Home equity $ $ First liens ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Mortgage Loans Aging (Table)	December 31, 2016 30 - 59 days 60 - 89 days 90 days or Total Current Total Recorded (in millions) Commercial-brick and mortar $ — $ — $ — $ — $ $ $ — Commercial-CTL — — — — — Residential-home equity — Residential-first liens ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 30 - 59 days 60 - 89 days 90 days or Total Current Total Recorded (in millions) Commercial-brick and mortar $ — $ — $ — $ — $ $ $ — Commercial-CTL — — — — — Residential-home equity — Residential-first liens ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Mortgage Loan Valuation Allowance (Table)	Commercial Residential Total (in millions) For the year ended December 31, 2016 Beginning balance $ $ $ Provision ) ) Charge-offs ) ) ) Recoveries — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2015 Beginning balance $ $ $ Provision — Charge-offs ) ) ) Recoveries Effect of exchange rates — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan balance by basis of impairment method: Individually evaluated for impairment $ — $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2014 Beginning balance $ $ $ Provision ) Charge-offs ) ) ) Recoveries — Effect of exchange rates — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance by basis of impairment method: Individually evaluated for impairment $ $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Allowance ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan balance by basis of impairment method: Individually evaluated for impairment $ $ $ Collectively evaluated for impairment ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loan ending balance $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Impaired Mortgage Loans (Table)	December 31, 2016 Recorded Unpaid Related (in millions) With no related allowance recorded: Residential-first liens $ $ $ — With an allowance recorded: Residential-home equity Residential-first liens Total: Residential $ $ $ December 31, 2015 Recorded Unpaid Related (in millions) With no related allowance recorded: Residential-first liens $ $ $ — With an allowance recorded: Residential-home equity Residential-first liens Total: Residential $ $ $ Average Interest income (in millions) For the year ended December 31, 2016 With no related allowance recorded: Residential-first liens $ $ — With an allowance recorded: Residential-home equity Residential-first liens Total: Residential $ $ For the year ended December 31, 2015 With no related allowance recorded: Commercial-brick and mortar $ $ — Residential-first liens — With an allowance recorded: Commercial-brick and mortar Residential-home equity Residential-first liens Total: Commercial $ $ Residential $ $ For the year ended December 31, 2014 With no related allowance recorded: Commercial-brick and mortar $ $ — Residential-first liens — With an allowance recorded: Commercial-brick and mortar Residential-home equity Residential-first liens Total: Commercial $ $ Residential $ $
Mortgage Loans Modified as a Troubled Debt Restructuring (Table)	For the year ended December 31, 2016 TDRs TDRs in payment default Number of Recorded Number of Recorded (in millions) (in millions) Residential-home equity $ — $ — Residential-first liens — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2015 TDRs TDRs in payment default Number of Recorded Number of Recorded (in millions) (in millions) Residential-home equity $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2014 TDRs TDRs in payment default Number of Recorded Number of Recorded (in millions) (in millions) Commercial-brick and mortar $ $ Residential-home equity — Residential-first liens — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Minority Interests in Unconsolidated Entities-Balance Sheet (Table)	December 31, 2016 2015 (in millions) Total assets $ $ Total liabilities ​ ​ ​ ​ ​ ​ ​ ​ Total equity $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net investment in unconsolidated entities (1) $ $
Minority Interests in Unconsolidated Entities-Income Statement (Table)	For the year ended December 31, 2016 2015 2014 (in millions) Total revenues $ $ $ Net income Our share of net income of unconsolidated entities (1) (1) Our most significant equity investee is Brasilprev Seguros e Previdencia, a co-managed joint venture in Brazil.
Financial Assets Subject to Netting Agreements (Table)	Gross amounts not offset in Gross amount Financial Collateral Net amount (in millions) December 31, 2016 Derivative assets $ $ ) $ ) $ Reverse repurchase agreements — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Derivative assets $ $ ) $ ) $ Reverse repurchase agreements — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The gross amount of recognized derivative and reverse repurchase agreement assets are reported with other investments and cash and cash equivalents, respectively, on the consolidated statements of financial position. The above excludes $6.4 million and $1.2 million of derivative assets as of December 31, 2016 and December 31, 2015, respectively, that are not subject to master netting agreements or similar agreements. The gross amounts of derivative and reverse repurchase agreement assets are not netted against offsetting liabilities for presentation on the consolidated statements of financial position. (2) Represents amount of offsetting derivative liabilities that are subject to an enforceable master netting agreement or similar agreement that are not netted against the gross derivative assets for presentation on the consolidated statements of financial position.
Financial Liabilities Subject to Netting Agreements (Table)	Gross amounts not offset in Gross amount Financial Collateral Net amount (in millions) December 31, 2016 Derivative liabilities $ $ ) $ ) $ Repurchase agreements — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Derivative liabilities $ $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The gross amount of recognized derivative liabilities are reported with other liabilities on the consolidated statements of financial position. The above excludes $394.3 million and $421.5 million of derivative liabilities as of December 31, 2016 and December 31, 2015, respectively, which are primarily embedded derivatives that are not subject to master netting agreements or similar agreements. The gross amount of recognized repurchase agreement liabilities are reported with short-term debt on the consolidated statements of financial position. The gross amounts of derivative and repurchase agreement liabilities are not netted against offsetting assets for presentation on the consolidated statements of financial position. (2) Represents amount of offsetting derivative assets that are subject to an enforceable master netting agreement or similar agreement that are not netted against the gross derivative liabilities for presentation on the consolidated statements of financial position.

Derivative Financial Instrume37

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Financial Instruments
Derivative Financial Instruments, Exposure (Table)	December 31, 2016 December 31, 2015 (in millions) Notional amounts of derivative instruments Interest rate contracts: Interest rate swaps $ $ Interest rate options Interest rate futures Swaptions Foreign exchange contracts: Currency swaps Currency forwards Equity contracts: Equity options Equity futures Credit contracts: Credit default swaps Total return swaps Futures Other contracts: Embedded derivatives ​ ​ ​ ​ ​ ​ ​ ​ Total notional amounts at end of period $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Credit exposure of derivative instruments Interest rate contracts: Interest rate swaps $ $ Interest rate options Foreign exchange contracts: Currency swaps Currency forwards Equity contracts: Equity options Credit contracts: Credit default swaps Total return swaps ​ ​ ​ ​ ​ ​ ​ ​ Total gross credit exposure Less: collateral received ​ ​ ​ ​ ​ ​ ​ ​ Net credit exposure $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Derivative Financial Instruments, Fair Value Disclosures (Table)	Derivative assets (1) Derivative liabilities (2) December 31, 2016 December 31, 2015 December 31, 2016 December 31, 2015 (in millions) Derivatives designated as hedging instruments Interest rate contracts $ $ $ $ Foreign exchange contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total derivatives designated as hedging instruments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivatives not designated as hedging instruments Interest rate contracts $ $ $ $ Foreign exchange contracts Equity contracts Credit contracts Other contracts — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total derivatives not designated as hedging instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total derivative instruments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value of derivative assets is reported with other investments on the consolidated statements of financial position. (2) The fair value of derivative liabilities is reported with other liabilities on the consolidated statements of financial position, with the exception of certain embedded derivative liabilities. Embedded derivative liabilities with a fair value of $176.5 million and $177.4 million as of December 31, 2016 and December 31, 2015, respectively, are reported with contractholder funds on the consolidated statements of financial position.
Credit Derivatives Sold (Table)	December 31, 2016 Notional Fair Maximum Weighted (in millions) Single name credit default swaps Corporate debt AAA $ $ $ AA A BBB B ) Near default Government/municipalities AA Sovereign AA BBB ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total single name credit default swaps Basket and index credit default swaps Corporate debt Near default (1) ) Government/municipalities AA ) Structured finance AA — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total basket and index credit default swaps ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total credit default swap protection sold $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Notional Fair Maximum Weighted (in millions) Single name credit default swaps Corporate debt AAA $ $ $ AA A BBB ) BB ) CCC ) Government/municipalities AA Sovereign AA — BBB ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total single name credit default swaps ) Basket and index credit default swaps Corporate debt Near default (1) ) Government/municipalities AA ) Structured finance AAA — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total basket and index credit default swaps ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total credit default swap protection sold $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes $60.0 million and $78.0 million as of December 31, 2016 and December 31, 2015, respectively, notional of derivatives in consolidated collateralized private investment vehicle VIEs where the credit risk is borne by third party investors.
Hybrid Instruments (Table)	December 31, 2016 Amortized Carrying Weighted (in millions) Structured finance AA $ $ BBB BB CCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total structured finance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities with credit derivatives $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Amortized Carrying Weighted (in millions) Corporate debt A $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total corporate debt Structured finance A BBB BB CCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total structured finance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities with credit derivatives $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Fair Value Hedges (Table)	Amount of gain Amount of gain Derivatives in fair value Hedged items in fair value 2016 2015 2014 2016 2015 2014 (in millions) (in millions) Interest rate contracts $ $ $ Fixed maturities, available-for-sale $ ) $ ) $ ) Interest rate contracts ) Investment contracts ) ) Foreign exchange contracts — Fixed maturities, available-for-sale — ) ) Foreign exchange contracts — — Investment contracts — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ Total $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The gain (loss) on both derivatives and hedged items in fair value relationships is reported in net realized capital gains (losses) on the consolidated statements of operations. The net amount represents the ineffective portion of our fair value hedges.
Fair Value Hedges, Periodic Settlements Disclosures (Table)	Amount of gain (loss) Hedged Item 2016 2015 2014 (in millions) Fixed maturities, available-for-sale (1) $ ) $ ) $ ) Investment contracts (2) (1) Reported in net investment income on the consolidated statements of operations. (2) Reported in benefits, claims and settlement expenses on the consolidated statements of operations.
Cash Flow Hedges (Table)	Amount of gain Amount of gain Location of gain (loss) Derivatives in cash flow Related hedged item 2016 2015 2014 2016 2015 2014 (in millions) (in millions) Interest rate contracts Fixed maturities, available-for-sale $ ) $ $ Net investment income $ $ $ Net realized capital gains — — Interest rate contracts Investment contracts Benefits, claims and settlement expenses — — — Interest rate contracts Debt — — — Operating expense ) ) ) Foreign exchange contracts Fixed maturities, available-for-sale Net realized capital gains (losses) ) Foreign exchange contracts Investment contracts Benefits, claims and settlement expenses — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ $ Total $ $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Cash Flow Hedges, Periodic Settlements Disclosures (Table)	Amount of gain (loss) Hedged item 2016 2015 2014 (in millions) Fixed maturities, available-for-sale (1) $ $ $ Investment contracts (2) ) ) ) (1) Reported in net investment income on the consolidated statements of operations. (2) Reported in benefits, claims and settlement expenses on the consolidated statements of operations.
Derivatives Not Designated as Hedging Instruments (Table)	Amount of gain (loss) Derivatives not designated as hedging instruments 2016 2015 2014 (in millions) Interest rate contracts $ $ $ Foreign exchange contracts ) ) Equity contracts ) ) Credit contracts ) Other contracts ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Closed Block (Tables)

Closed Block (Tables)	12 Months Ended
	Dec. 31, 2016
Closed Block
Closed Block Liabilities and Assets Designated to the Closed Block (Table)	December 31, 2016 December 31, 2015 (in millions) Closed Block liabilities Future policy benefits and claims $ $ Other policyholder funds Policyholder dividends payable Policyholder dividends obligation Other liabilities ​ ​ ​ ​ ​ ​ ​ ​ Total Closed Block liabilities Assets designated to the Closed Block Fixed maturities, available-for-sale Fixed maturities, trading Equity securities, available-for-sale Mortgage loans Policy loans Other investments ​ ​ ​ ​ ​ ​ ​ ​ Total investments Cash and cash equivalents Accrued investment income Premiums due and other receivables Deferred tax asset Other assets — ​ ​ ​ ​ ​ ​ ​ ​ Total assets designated to the Closed Block ​ ​ ​ ​ ​ ​ ​ ​ Excess of Closed Block liabilities over assets designated to the Closed Block Amounts included in accumulated other comprehensive income ​ ​ ​ ​ ​ ​ ​ ​ Maximum future earnings to be recognized from Closed Block assets and liabilities $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Closed Block Revenues and Expenses (Table)	For the year ended 2016 2015 2014 (in millions) Revenues Premiums and other considerations $ $ $ Net investment income Net realized capital losses ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Benefits, claims and settlement expenses Dividends to policyholders Operating expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues, net of Closed Block expenses, before income taxes Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues, net of Closed Block expenses and income taxes Funding adjustment charges ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Closed Block revenues, net of Closed Block expenses, income taxes and funding adjustment charges $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Change in Maximum Future Earnings of the Closed Block (Table)	For the year ended 2016 2015 2014 (in millions) Beginning of year $ $ $ End of year ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in maximum future earnings $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Deferred Acquisition Costs (Tab

Deferred Acquisition Costs (Tables)	12 Months Ended
	Dec. 31, 2016
Deferred Acquisition Costs
Deferred Acquisition Costs Rollforward (Table)	For the year ended 2016 2015 2014 (in millions) Balance at beginning of year $ $ $ Costs deferred during the year Amortized to expense during the year (1) ) ) ) Adjustment related to unrealized (gains) losses on available-for-sale securities and derivative instruments ) ) Other — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes adjustments for revisions to estimated gross profits.

Insurance Liabilities (Tables)

Insurance Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Contractholder Funds (Table)	December 31, 2016 2015 (in millions) Liabilities for investment contracts: Liabilities for individual annuities $ $ GICs Funding agreements Other investment contracts ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities for investment contracts Universal life and other reserves ​ ​ ​ ​ ​ ​ ​ ​ Total contractholder funds $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Liability for Unpaid Claims (Table)	December 31, 2016 2015 2014 (in millions) Balance at beginning of year $ $ $ Less: reinsurance recoverable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net balance at beginning of year Incurred: Current year Prior years ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total incurred Payments: Current year Prior years ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total payments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net balance at end of year Plus: reinsurance recoverable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts not included in the rollforward above: Claim adjustment expense liabilities $ $ $
Reconciliation of unpaid claims to liability for unpaid claims (Table)	December 31, 2016 LTD and Dental, Group Consolidated (in millions) Net outstanding liabilities for unpaid claims $ $ $ $ Reconciling items: Reinsurance recoverable on unpaid claims — Impact of discounting ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liability for unpaid claims — short-duration contracts $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Insurance contracts other than short-duration ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liability for unpaid claims $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Claim Duration and Payout (Table)	December 31, 2016 Year LTD and Dental, Group 1 % % % 2 3 4 5 6 7 8 9 10
Discounting (Table)	LTD and Group Dental, Vision Group Life ($ in millions) Carrying amount of liabilities for unpaid claims December 31, 2016 $ $ $ December 31, 2015 Range of discount rates December 31, 2016 3.3 - 7.0 % — - — % — - — % December 31, 2015 3.3 - 7.0 — - — — - — Aggregate amount of discount December 31, 2016 $ $ — $ — December 31, 2015 — — Interest accretion For the year ended: December 31, 2016 $ $ — $ — December 31, 2015 — — December 31, 2014 — —
Long-Term Disability/Group Life Waiver
Claims Development (Table)	Net incurred claims (1) Incurred Cumulative December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2016 2016 ($ in millions) Incurral year 2007 $ $ $ $ $ $ $ $ $ $ $ 2008 2009 2010 2011 2012 2013 2014 2015 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net incurred claims $ Net cumulative paid claims (1) December 31, 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 (in millions) Incurral year 2007 $ $ $ $ $ $ $ $ $ $ 2008 2009 2010 2011 2012 2013 2014 2015 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net paid claims All outstanding liabilities for unpaid claims prior to 2007 net of reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total outstanding liabilities for unpaid claims net of reinsurance $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) 2007 - 2015 unaudited.
Dental/Vision/Short-Term Disability
Claims Development (Table)	Net incurred Incurred Cumulative December 31, 2015 2016 2016 2016 ($ in millions) Incurral year 2015 $ $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net incurred claims $ Net cumulative December 31, 2015 2016 (in millions) Incurral year 2015 $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net paid claims All outstanding liabilities for unpaid claims prior to 2015 net of reinsurance — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total outstanding liabilities for unpaid claims net of reinsurance $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) 2015 unaudited.
Group Life
Claims Development (Table)	Net incurred Incurred Cumulative December 31, 2015 2016 2016 2016 ($ in millions) Incurral year 2015 $ $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net incurred claims $ Net cumulative December 31, 2015 2016 (in millions) Incurral year 2015 $ $ 2016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total net paid claims All outstanding liabilities for unpaid claims prior to 2015 net of reinsurance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total outstanding liabilities for unpaid claims net of reinsurance $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) 2015 unaudited.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2016
Debt
Short-Term Debt (Table)	December 31, 2016 2015 (in millions) Line of credit $ $ Other recourse short-term debt — ​ ​ ​ ​ ​ ​ ​ ​ Total short-term debt $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Long-Term Debt (Table)	December 31, 2016 Principal Net unamortized Carrying (in millions) 3.3% notes payable, due 2022 $ $ ) $ 3.125% notes payable, due 2023 ) 3.4% notes payable, due 2025 ) 3.1% notes payable, due 2026 ) 6.05% notes payable, due 2036 ) 4.625% notes payable, due 2042 ) 4.35% notes payable, due 2043 ) 4.3% notes payable, due 2046 ) 4.7% notes payable, due 2055 ) Non-recourse mortgages and notes payable (1) — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total long-term debt $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Principal Net unamortized Carrying (in millions) 1.85% notes payable, due 2017 $ $ ) $ 8.875% notes payable, due 2019 ) 3.3% notes payable, due 2022 ) 3.125% notes payable, due 2023 ) 3.4% notes payable, due 2025 ) 6.05% notes payable, due 2036 ) 4.625% notes payable, due 2042 ) 4.35% notes payable, due 2043 ) 4.7% notes payable, due 2055 ) Non-recourse mortgages and notes payable (1) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total long-term debt $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Includes external debt issuance costs incurred for long-term affiliated debt issued in a foreign jurisdiction.
Future Annual Maturities of Long-Term Debt (Table)	As of December 31, 2016, future annual maturities of long-term debt were as follows (in millions): Year ending December 31: 2017 $ — 2018 — 2019 — 2020 — 2021 — Thereafter ​ ​ ​ ​ ​ Total future maturities of long-term debt $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Taxes
Income Tax Expense (Benefit) from Continuing Operations (Table)	For the year ended 2016 2015 2014 (in millions) Current income taxes: U.S. federal $ $ $ State ) Foreign Tax benefit of operating loss carryforward ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total current income taxes Deferred income taxes (benefits): U.S. federal State ) ) ) Foreign ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total deferred income taxes (benefits) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income taxes $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Reconciliation Between U.S. Corporate Income Tax Rate and Effective Income Tax Rate from Continuing Operations (Table)	For the year ended 2016 2015 2014 U.S. corporate income tax rate % % % Dividends received deduction ) ) ) Impact of equity method presentation ) ) ) Tax credits ) ) ) Interest exclusion from taxable income ) ) ) Foreign country permanent tax adjustments ) — — Impact of noncontrolling interest presentation ) — — Merger of Chilean legal entities — ) — Foreign tax rate differential — — ) Impact of court ruling on some uncertain tax positions — — Impact of enactment of tax legislation — — Other ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective income tax rate % % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Income Before Income Taxes, Domestic and Foreign (Table)	For the year ended 2016 2015 2014 (in millions) Domestic $ $ $ Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income before income taxes $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Changes in Unrecognized Tax Benefits (Table)	For the year 2016 2015 (in millions) Balance at beginning of period $ $ Additions based on tax positions related to the current year Additions for tax positions of prior years Reductions for tax positions related to the current year ) ) Reductions for tax positions of prior years ) ) ​ ​ ​ ​ ​ ​ ​ ​ Balance at end of period (1) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Of this amount, $81.0 million, if recognized, would reduce the 2016 effective income tax rate. We recognize interest and penalties related to uncertain tax positions in operating expenses within the consolidated statements of operations.
Components of Net Deferred Income Taxes (Table)	December 31, 2016 2015 (in millions) Deferred income tax assets: Insurance liabilities $ $ Investments, including derivatives Net operating and capital loss carryforwards Tax credit carryforwards Employee benefits Foreign currency translation Other deferred income tax assets ​ ​ ​ ​ ​ ​ ​ ​ Gross deferred income tax assets Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred income tax assets Deferred income tax liabilities: Deferred acquisition costs ) ) Investments, including derivatives ) ) Net unrealized gains on available-for-sale securities ) ) Real estate ) ) Intangible assets ) ) Other deferred income tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred income tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total net deferred income tax liabilities $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Net Deferred Income Taxes by Jurisdiction (Table)	December 31, 2016 2015 (in millions) Deferred income tax assets: State $ $ Foreign ​ ​ ​ ​ ​ ​ ​ ​ Net deferred income tax assets Deferred income tax liabilities: U.S. federal ) ) Foreign ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred income tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total net deferred income tax liabilities $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Employee and Agent Benefits (Ta

Employee and Agent Benefits (Tables)	12 Months Ended
	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans
Obligations and Funded Status (Table)	Pension benefits Other December 31, December 31, 2016 2015 2016 2015 (in millions) Change in benefit obligation Benefit obligation at beginning of year $ ) $ ) $ ) $ ) Service cost ) ) ) ) Interest cost ) ) ) ) Actuarial gain (loss) ) ) Participant contribution — — ) ) Benefits paid Plan amendments — — Other — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at end of year $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in plan assets Fair value of plan assets at beginning of year $ $ $ $ Actual return on plan assets ) ) Employer contribution Participant contributions — — Benefits paid ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount recognized in statement of financial position Other assets $ — $ — $ $ Other liabilities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ ) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount recognized in accumulated other comprehensive (income) loss Total net actuarial (gain) loss $ $ $ $ ) Prior service benefit ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax accumulated other comprehensive (income) loss $ $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Components of Net Periodic Benefit Cost (Income) (Table)	Pension benefits Other postretirement For the year ended December 31, 2016 2015 2014 2016 2015 2014 (in millions) Service cost $ $ $ $ $ $ Interest cost Expected return on plan assets ) ) ) ) ) ) Amortization of prior service benefit ) ) ) ) ) ) Recognized net actuarial (gain) loss ) ) Plan amendments — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net periodic benefit cost (income) $ $ $ $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Amounts Recognized in Net Periodic Benefit Cost and Accumulated Other Comprehensive (Income) Loss (Table)	Pension Other For the year ended December 31, 2016 2015 2016 2015 (in millions) Other changes recognized in accumulated other comprehensive (income) loss Net actuarial loss $ $ $ $ Amortization of gain (loss) ) ) ) Amortization of prior service benefit Plan amendments — — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in pre-tax accumulated other comprehensive (income) loss $ ) $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Weighted-Average Assumptions Used to Determine Benefit Obligations (Table)	Pension benefits For the year ended 2016 2015 Discount rate % % Rate of compensation increase: Cash balance benefit % % Traditional benefit % % Other For the year ended 2016 2015 Discount rate % % Rate of compensation increase % %
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Table)	Pension benefits For the year ended 2016 2015 2014 Discount rate % % % Expected long-term return on plan assets % % % Rate of compensation increase: Cash balance benefit % % % Traditional benefit % % % Other For the year ended 2016 2015 2014 Discount rate (1) % % % Expected long-term return on plan assets % % % Rate of compensation increase % % % (1) The funded statuses of the affected plans were remeasured as of October 31, 2016, and a portion of the impact was reflected in the 2016 net periodic postretirement benefit cost. A discount rate of 4.15% was used until the remeasurement date at which time a discount rate of 3.35% was used.
Assumed Health Care Cost Trend Rates (Table)	December 31, 2016 2015 Health care cost trend rate assumed for next year under age 65 % % Health care cost trend rate assumed for next year age 65 and over % % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) % % Year that the rate reaches the ultimate trend rate (under age 65) Year that the rate reaches the ultimate trend rate (65 and older)
Effects of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Table)	1-percentage 1-percentage (in millions) Effect on total of service cost and interest cost components $ $ ) Effect on accumulated postretirement benefit obligation )
Estimated Future Benefit Payments (Table)	Pension benefits Other postretirement Amount of Medicare (in millions) Year ending December 31: 2017 $ $ $ 2018 2019 2020 2021 2022-2026
Defined Benefit Pension Plans Supplemental Information (Table)	For the year ended December 31, 2016 2015 Qualified Nonqualified Total Qualified Nonqualified Total (in millions) Amount recognized in statement of financial position Other assets $ — $ — $ — $ — $ — $ — Other liabilities ) ) ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ ) $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount recognized in accumulated other comprehensive loss Total net actuarial loss $ $ $ $ $ $ Prior service benefit ) ) ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax accumulated other comprehensive loss $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Components of net periodic benefit cost Service cost $ $ $ $ $ $ Interest cost Expected return on plan assets ) — ) ) — ) Amortization of prior service benefit ) ) ) ) ) ) Recognized net actuarial loss ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net periodic benefit cost $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other changes recognized in accumulated other comprehensive (income) loss Net actuarial (gain) loss $ ) $ $ $ $ ) $ Amortization of net loss ) ) ) ) ) ) Amortization of prior service benefit ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in pre-tax accumulated other comprehensive (income) loss $ ) $ $ ) $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss $ $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Pension benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Accumulated Benefit Obligation in Excess of Plan Assets (Table)	December 31, 2016 2015 (in millions) Projected benefit obligation $ $ Accumulated benefit obligation Fair value of plan assets
Fair Value of Plan Assets (Table)	December 31, 2016 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category U.S. large cap equity portfolios (1) $ $ — $ $ — U.S. small/mid cap equity portfolios (2) — — Balanced asset portfolios (3) — — International equity portfolios (4) — — Fixed income security portfolios (5) — — Real estate investment portfolios (6) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ — $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category U.S. large cap equity portfolios (1) $ $ — $ $ — U.S. small/mid cap equity portfolios (2) — — Balanced asset portfolios (3) — — International equity portfolios (4) — — Fixed income security portfolios (5) — — Real estate investment portfolios (6) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ — $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The portfolios invest primarily in publicly traded equity securities of large U.S. companies. (2) The portfolios invest primarily in publicly traded equity securities of mid-sized and small U.S. companies. (3) The portfolios are a combination of underlying fixed income and equity investment options. These investment options may include balanced, asset allocation, target-date and target-risk investment options. Although typically lower risk than investment options that invest solely in equities, all investment options in this category have the potential to lose value. (4) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies. (5) The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations. (6) The portfolio invests primarily in U.S. commercial real estate properties through a separate account.
Target Asset Allocation (Table)	Asset category Target allocation U.S. equity portfolios 0% - 45% International equity portfolios 0% - 15% Fixed income security portfolios 30% - 100% Real estate investment portfolios 0% - 10%
Other postretirement benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Accumulated Benefit Obligation in Excess of Plan Assets (Table)	December 31, 2016 2015 (in millions) Accumulated postretirement benefit obligation $ $ Fair value of plan assets
Fair Value of Plan Assets (Table)	December 31, 2016 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category Cash and cash equivalents $ $ $ — $ — Fixed income security portfolios: Fixed income investment funds (1) — U.S. equity portfolios (3) — International equity portfolios (4) — Alternative mutual fund portfolios (5) — — Real estate mutual fund (6) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Fair value hierarchy level Assets Level 1 Level 2 Level 3 (in millions) Asset category Cash and cash equivalents $ $ $ — $ — Fixed income security portfolios: Fixed income investment funds (1) — Principal Life general account investment (2) — — U.S. equity portfolios (3) — International equity portfolios (4) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations. (2) The general account is invested in various fixed income securities. (3) The portfolios invest primarily in publicly traded equity securities of large U.S. companies. (4) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies. (5) The portfolios invest primarily in equities, corporate bonds, foreign currencies, convertible securities and derivatives. (6) The mutual fund invests primarily in U.S. commercial real estate properties.
Target Asset Allocation (Table)	Asset category Target allocation U.S. equity portfolios % International equity portfolios % Fixed income security portfolios % Alternatives % Real estate %
Reconciliation of Plan Assets Measured at Fair Value Using Significant Unobservable Inputs (Table)	For the year ended December 31, 2016 Actual return gains Ending Beginning Relating to Relating to Net Transfers Transfers (in millions) Asset category Principal Life general account investment $ $ ) $ ) $ $ — $ — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2015 Actual return gains Ending Beginning Relating to Relating to Net Transfers Transfers (in millions) Asset category Principal Life general account investment $ $ $ — $ ) $ — $ — $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2014 Actual return gains Ending Beginning Relating to Relating to Net Transfers Transfers (in millions) Asset category Principal Life general account investment $ $ $ — $ ) $ — $ — $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Contingencies, Guarantees and44

Contingencies, Guarantees and Indemnifications (Tables)	12 Months Ended
	Dec. 31, 2016
Contingencies, Guarantees and Indemnifications
Operating Lease Obligations (Table)	The following represents payments due by period for operating lease obligations (in millions): Year ending December 31: 2017 $ 2018 2019 2020 2021 2022 and thereafter ​ ​ ​ ​ ​ Total operating lease obligations Less: Future sublease rental income on noncancelable leases ​ ​ ​ ​ ​ Total future minimum lease payments $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Capital Leases Future Minimum Lease Payments (Table)	The following represents future minimum lease payments due by period for capital lease obligations (in millions). Year ending December 31: 2017 $ 2018 2019 2020 2021 2022 and thereafter ​ ​ ​ ​ ​ Total Less: Amounts representing interest ​ ​ ​ ​ ​ Net present value of minimum lease payments $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2016
Stockholders' Equity
Reconciliation of Outstanding Shares (Table)	Series A Series B Common (in millions) Outstanding shares as of January 1, 2014 Shares issued — — Treasury stock acquired — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding shares as of December 31, 2014 Shares issued — — Treasury stock acquired — — ) Preferred stock redemption ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding shares as of December 31, 2015 — — Shares issued — — Treasury stock acquired — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding shares as of December 31, 2016 — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Other Comprehensive Income (Loss) (Table)	For the year ended Pre-Tax Tax After-Tax (in millions) Net unrealized gains on available-for-sale securities during the period $ $ ) $ Reclassification adjustment for losses included in net income (1) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on available-for-sale securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale during the period ) ) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale (2) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments during the period ) Reclassification adjustment for gains included in net income (3) ) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized postretirement benefit obligation during the period ) Amortization of prior service cost and actuarial loss included in net periodic benefit cost (4) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrecognized postretirement benefit obligation ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended Pre-Tax Tax After-Tax (in millions) Net unrealized losses on available-for-sale securities during the period $ ) $ $ ) Reclassification adjustment for losses included in net income (1) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized losses on available-for-sale securities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale during the period ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale (2) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments during the period ) Reclassification adjustment for gains included in net income (3) ) ) Adjustments for assumed changes in amortization patterns ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized postretirement benefit obligation during the period ) ) Amortization of prior service cost and actuarial loss included in net periodic benefit cost (4) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrecognized postretirement benefit obligation ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss $ ) $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended Pre-Tax Tax After-Tax (in millions) Net unrealized gains on available-for-sale securities during the period $ $ ) $ Reclassification adjustment for gains included in net income (1) ) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on available-for-sale securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale during the period ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncredit component of impairment losses on fixed maturities, available-for-sale (2) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments during the period ) Reclassification adjustment for losses included in net income (3) ) Adjustments for assumed changes in amortization patterns ) ) Adjustments for assumed changes in policyholder liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrealized gains on derivative instruments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrecognized postretirement benefit obligation during the period ) ) Amortization of prior service cost and actuarial loss included in net periodic benefit cost (4) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net unrecognized postretirement benefit obligation ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Pre-tax reclassification adjustments relating to available-for-sale securities are reported in net realized capital gains (losses) on the consolidated statements of operations. (2) Represents the net impact of (1) unrealized gains resulting from reclassification of previously recognized noncredit impairment losses from OCI to net realized capital gains (losses) for fixed maturities with bifurcated OTTI that had additional credit losses or fixed maturities that previously had bifurcated OTTI that have now been sold or are intended to be sold and (2) unrealized losses resulting from reclassification of noncredit impairment losses for fixed maturities with bifurcated OTTI from net realized capital gains (losses) to OCI. (3) See Note 5, Derivative Financial Instruments — Cash Flow Hedges, for further details. (4) Pre-tax amortization of prior service cost and actuarial loss included in net periodic benefit cost, which is comprised of amortization of prior service cost (benefit) and recognized net actuarial (gain) loss, is reported in operating expenses on the consolidated statements of operations. See Note 11, Employee and Agent Benefits — Components of Net Periodic Benefit Cost, for further details.
Accumulated Other Comprehensive Income (Loss) (Table)	Net unrealized Noncredit Net unrealized Foreign Unrecognized Accumulated (in millions) Balances as of January 1, 2014 $ $ ) $ ) $ ) $ ) $ Other comprehensive loss during the period, net of adjustments — ) ) ) Amounts reclassified from AOCI ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balances as of December 31, 2014 ) ) ) Other comprehensive loss during the period, net of adjustments ) — ) ) ) Amounts reclassified from AOCI ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive loss ) ) ) ) Purchase of subsidiary shares from noncontrolling interest — — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balances as of December 31, 2015 ) ) ) ) Other comprehensive income during the period, net of adjustments ) Amounts reclassified from AOCI — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income ) Purchase of subsidiary shares from noncontrolling interest — — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balances as of December 31, 2016 $ $ ) $ $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Redeemable Noncontrolling Interest (Table)	Following is a reconciliation of the changes in the redeemable noncontrolling interest (in millions): Balance as of January 1, 2014 $ Net income attributable to redeemable noncontrolling interest Contributions from redeemable noncontrolling interest Distributions to redeemable noncontrolling interest ) Purchase of subsidiary shares from redeemable noncontrolling interest (1) ) Change in redemption value of redeemable noncontrolling interest Other comprehensive income attributable to redeemable noncontrolling interest ) ​ ​ ​ ​ ​ Balance as of December 31, 2014 Net income attributable to redeemable noncontrolling interest Contributions from redeemable noncontrolling interest Distributions to redeemable noncontrolling interest ) Purchase of subsidiary shares from redeemable noncontrolling interest ) Change in redemption value of redeemable noncontrolling interest Other comprehensive income attributable to redeemable noncontrolling interest ) ​ ​ ​ ​ ​ Balance as of December 31, 2015 Net income attributable to redeemable noncontrolling interest Redeemable noncontrolling interest of newly consolidated entities (2) Redeemable noncontrolling interest of deconsolidated entities (3) ) Contributions from redeemable noncontrolling interest Distributions to redeemable noncontrolling interest ) Purchase of subsidiary shares from redeemable noncontrolling interest ) Change in redemption value of redeemable noncontrolling interest Other comprehensive income attributable to redeemable noncontrolling interest ​ ​ ​ ​ ​ Balance as of December 31, 2016 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) During the third quarter of 2014, we increased our ownership stake in Columbus Circle Investors. (2) Effective January 1, 2016, certain sponsored investment funds were consolidated as a result of the implementation of new accounting guidance. See Note 3, Variable Interest Entities, for further details. (3) We deconsolidated certain sponsored investment funds as they no longer met the requirements for consolidation.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Measurements
Fair Value (Table)	December 31, 2016 Assets/ Amount Fair value hierarchy level Level 1 Level 2 Level 3 (in millions) Assets Fixed maturities, available-for-sale: U.S. government and agencies $ $ — $ $ $ — Non-U.S. governments — States and political subdivisions — — — Corporate — Residential mortgage-backed securities — — — Commercial mortgage-backed securities — — Collateralized debt obligations — — Other debt obligations — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — Fixed maturities, trading — — Equity securities, available-for-sale — Equity securities, trading — — Derivative assets (1) — — Other investments (2) Cash equivalents (3) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sub-total excluding separate account assets Separate account assets — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Investment contracts (4) $ ) $ — $ — $ — $ ) Derivative liabilities (1) ) — — ) ) Other liabilities (4) ) — — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities $ ) $ — $ — $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2015 Assets/ Amount Fair value hierarchy level Level 1 Level 2 Level 3 (in millions) Assets Fixed maturities, available-for-sale: U.S. government and agencies $ $ — $ $ $ — Non-U.S. governments — States and political subdivisions — — — Corporate — Residential mortgage-backed securities — — — Commercial mortgage-backed securities — — Collateralized debt obligations — — Other debt obligations — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — Fixed maturities, trading — Equity securities, available-for-sale — Equity securities, trading — — Derivative assets (1) — — Other investments (2) Cash equivalents (3) — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sub-total excluding separate account assets Separate account assets — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Investment contracts (4) $ ) $ — $ — $ — $ ) Derivative liabilities (1) ) — — ) ) Other liabilities (4) ) — — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities $ ) $ — $ — $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net assets $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Within the consolidated statements of financial position, derivative assets are reported with other investments and derivative liabilities are reported with other liabilities. Refer to Note 5, Derivative Financial Instruments, for further information on fair value by class of derivative instruments. Our derivatives are primarily Level 2, with the exception of certain credit default swaps and other swaps that are Level 3. (2) Primarily includes sponsored investment funds, other investment funds, equity method investments reported at fair value and commercial mortgage loans of consolidated VIEs. (3) Includes money market instruments and short-term investments with a maturity date of three months or less when purchased. (4) Includes bifurcated embedded derivatives that are reported at fair value within the same line item in the consolidated statements of financial position in which the host contract is reported. Other liabilities also include obligations of consolidated VIEs reported at fair value. (5) Certain investments are measured at fair value using the NAV per share (or its equivalent) practical expedient and have not been classified in the fair value hierarchy. These consist of certain fund interests that are restricted until maturity with unfunded commitments totaling $57.6 million and $7.3 million as of December 31, 2016 and December 31, 2015, respectively.
Reconciliation for All Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Table)	For the year ended December 31, 2016 Total realized/unrealized Changes in Beginning Ending Net purchases, Included Included Transfers Transfers (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ $ $ — $ ) $ $ ) Corporate ) ) ) ) Commercial mortgage-backed securities ) ) ) Collateralized debt obligations — ) — — — Other debt obligations — — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) ) ) Fixed maturities, trading — ) — — Equity securities, available-for-sale ) ) — — — ) Derivative assets ) — — — ) Other investments — — — Separate account assets (2) — ) ) Liabilities Investment contracts ) ) — — — ) ) Derivative liabilities ) — — ) Other liabilities ) ) — — — ) ) For the year ended December 31, 2015 Total realized/unrealized Changes in Beginning Ending Net purchases, Included Included Transfers Transfers (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ ) $ $ — $ — $ $ ) Corporate ) ) ) ) Commercial mortgage-backed securities — — — ) — Collateralized debt obligations — ) ) — — — Other debt obligations — — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) ) ) ) Fixed maturities, trading ) — ) — — ) Equity securities, available-for-sale — — — — — — Derivative assets ) — — — ) Other investments — ) — ) Separate account assets (2) — ) Liabilities Investment contracts ) ) — — — ) ) Derivative liabilities ) ) — — ) ) Other liabilities ) ) — — — — ) ) For the year ended December 31, 2014 Changes in Total realized/unrealized Beginning Ending Net purchases, Included Included Transfers Transfers (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ — $ — $ $ ) States and political subdivisions — — ) — ) — — Corporate ) ) ) ) Commercial mortgage-backed securities ) ) ) — — Collateralized debt obligations — ) — Other debt obligations — — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) ) ) Fixed maturities, trading — ) — — Equity securities, available-for-sale ) — ) Derivative assets ) — — — ) Other investments — ) — — Separate account assets (2) — ) ) Liabilities Investment contracts ) ) — — — ) ) Derivative liabilities ) ) — — ) ) Other liabilities ) ) — — — ) ) (1) Both realized gains (losses) and mark-to-market unrealized gains (losses) are generally reported in net realized capital gains (losses) within the consolidated statements of operations. Realized and unrealized gains (losses) on certain fixed maturities, trading and certain derivatives used in relation to certain trading portfolios are reported in net investment income within the consolidated statements of operations. (2) Gains and losses for separate account assets do not impact net income as the change in value of separate account assets is offset by a change in value of separate account liabilities. Foreign currency translation adjustments related to the Principal International segment separate account assets are recorded in AOCI and are offset by foreign currency translation adjustments of the corresponding separate account liabilities. (3) Gross purchases, sales, issuances and settlements were: For the year ended December 31, 2016 Purchases Sales Issuances Settlements Net purchases, (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ Corporate ) — ) Commercial mortgage-backed securities — — ) Collateralized debt obligations — — — ) ) Other debt obligations ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) — ) Fixed maturities, trading — ) — ) ) Derivative assets — — Other investments ) — — Separate account assets (4) ) ) ) Liabilities Investment contracts — — Derivative liabilities — — — Other liabilities — — — For the year ended December 31, 2015 Purchases Sales Issuances Settlements Net purchases, (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ Corporate ) — ) Commercial mortgage-backed securities — — ) Collateralized debt obligations — — — ) ) Other debt obligations — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) — ) Fixed maturities, trading — ) — — ) Derivative assets ) — — Other investments ) — — ) Separate account assets (4) ) ) Liabilities Investment contracts — — Derivative liabilities — — — For the year ended December 31, 2014 Purchases Sales Issuances Settlements Net purchases, (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ $ ) $ — $ ) $ ) States and political subdivisions — — — ) ) Corporate ) — ) Commercial mortgage-backed securities — ) — ) ) Collateralized debt obligations — — ) Other debt obligations — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale ) — ) Fixed maturities, trading — ) — ) ) Equity securities, available-for-sale — ) — — ) Derivative assets ) — — Other investments — — ) ) Separate account assets (4) ) ) ) Liabilities Investment contracts — — Derivative liabilities ) — — Other liabilities — — — (4) Issuances and settlements include amounts related to mortgage encumbrances associated with real estate in our separate accounts.
Transfers (Table)	For the year ended December 31, 2016 Transfers out Transfers out Transfers out Transfers out Transfers out Transfers out (in millions) Assets Fixed maturities, available-for- sale: Non-U.S. governments $ — $ — $ — $ — $ — $ Corporate — — — — Commercial mortgage-backed securities — — — — Other debt obligations — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — — — — Separate account assets — — For the year ended December 31, 2015 Transfers out Transfers out Transfers out Transfers out Transfers out Transfers out (in millions) Assets Fixed maturities, available-for- sale: Corporate $ — $ — $ — $ $ — $ Commercial mortgage-backed securities — — — — — Other debt obligations — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — — — — Other investments — — — — Separate account assets — — For the year ended December 31, 2014 Transfers out Transfers out Transfers out Transfers out Transfers out Transfers out (in millions) Assets Fixed maturities, available-for- sale: States and political subdivisions $ — $ — $ — $ — $ — $ Corporate — — — — Commercial mortgage-backed securities — — — — Collateralized debt obligations — — — — Other debt obligations — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total fixed maturities, available-for-sale — — — — Equity securities, available-for- sale — — — — — Separate account assets — —
Quantitative Information about Level 3 Fair Value Measurements (Table)	December 31, 2016 Assets / Valuation Unobservable Input/range of Weighted (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ Discounted cash flow Discount rate (1) Illiquidity premium 50 basis points ("bps") 50bps Comparability adjustment (25)bps (25)bps Corporate Discounted cash flow Discount rate (1) 1.5% - 7.6% Illiquidity premium 0bps - 60bps 27bps Comparability adjustment 0bps - 20bps 6bps Commercial mortgage-backed securities Discounted cash flow Discount rate (1) 3.1% - 12.8% Probability of default 0.0% - 10.0% Potential loss severity 0.0% - 99.5% Collateralized debt obligations Discounted cash flow Discount rate (1) Probability of default Potential loss severity Other debt obligations Discounted cash flow Discount rate (1) Illiquidity premium 500bps 500bps Fixed maturities, trading Discounted cash flow Discount rate (1) 2.3% - 9.0% Illiquidity premium 0bps - 300bps 240bps Other investments Discounted cash flow — equity method real estate investments Discount rate (1) Terminal capitalization rate Average market rent growth rate Discounted cash flow — equity method real estate investments — debt Loan to value Credit spread rate Separate account assets Discounted cash flow — mortgage loans Discount rate (1) 1.4% - 5.3% Illiquidity premium 0bps - 60bps 13bps Credit spread rate 83bps - 472bps 227bps Discounted cash flow — real estate Discount rate (1) 5.8% - 16.2% Terminal capitalization rate 4.3% - 9.3% Average market rent growth rate 1.8% - 4.3% Discounted cash flow — real estate debt Loan to value 6.3% - 69.7% Credit spread rate 3.3% - 4.6% Liabilities Investment contracts ) Discounted cash flow Long duration interest rate 2.6% - 2.7% (2) Long-term equity market volatility 16.0% - 45.9% Non-performance risk 0.3% - 1.7% Utilization rate See note (3) Lapse rate 0.5% - 14.1% Mortality rate See note (4) December 31, 2015 Assets / Valuation Unobservable Input/range of Weighted (in millions) Assets Fixed maturities, available-for-sale: Non-U.S. governments $ Discounted cash flow Discount rate (1) Illiquidity premium 50bps 50bps Corporate Discounted cash flow Discount rate (1) 0.0% - 7.5% Comparability adjustment (4)bps - 7bps 0bps Illiquidity premium 0bps - 60bps 33bps Collateralized debt obligations Discounted cash flow Discount rate (1) Probability of default Potential loss severity Other debt obligations Discounted cash flow Discount rate (1) Illiquidity premium 750bps 750bps Fixed maturities, trading Discounted cash flow Discount rate (1) 1.1% - 2.7% Illiquidity premium 0bps - 300bps 240bps Other investments Discounted cash flow — equity method real estate investments Discount rate (1) Terminal capitalization rate Average market rent growth rate Discounted cash flow — equity method real estate investments — debt Loan to value Credit spread rate Separate account assets Discounted cash flow — mortgage loans Discount rate (1) 1.4% - 8.2% Illiquidity premium 0bps - 60bps 7bps Credit spread rate 81bps - 750bps 241bps Discounted cash flow — real estate Discount rate (1) 5.3% - 16.4% Terminal capitalization rate 4.3% - 9.8% Average market rent growth rate 2.0% - 4.3% Discounted cash flow — real estate debt Loan to value 7.8% - 63.1% Credit spread rate 1.4% - 4.6% Liabilities Investment contracts ) Discounted cash flow Long duration interest rate 2.5% - 2.6% (2) Long-term equity market volatility 14.9% - 44.4% Non-performance risk 0.4% - 1.9% Utilization rate See note (3) Lapse rate 0.5% - 14.1% Mortality rate See note (4) (1) Represents market comparable interest rate or an index adjusted rate used as the base rate in the discounted cash flow analysis prior to any credit spread, illiquidity or other adjustments, where applicable. (2) Represents the range of rate curves used in the valuation analysis that we have determined market participants would use when pricing the instrument. Derived from interpolation between various observable swap rates. (3) This input factor is the number of contractholders taking withdrawals as well as the amount and timing of the withdrawals and a range does not provide a meaningful presentation. (4) This input is based on an appropriate industry mortality table and a range does not provide a meaningful presentation.
Fair Value Option (Table)	December 31, 2016 December 31, 2015 (in millions) Commercial mortgage loans of consolidated VIEs (1)(2) Fair value $ $ Aggregate contractual principal Obligations of consolidated VIEs (3) Fair value Aggregate unpaid principal Real estate ventures (1) Fair value Investment funds (1)(4) Fair value — (1) Reported with other investments in the consolidated statements of financial position. (2) None of the loans were more than 90 days past due or in non-accrual status. (3) Reported with other liabilities in the consolidated statements of financial position. (4) We did not have any material investment funds for which we elected the fair value option for the year ended December 31, 2015. For the year ended 2016 2015 2014 Commercial mortgage loans of consolidated VIEs Change in fair value pre-tax loss (1)(2) $ ) $ ) $ ) Interest income (3) Obligations of consolidated VIEs Change in fair value pre-tax loss — instrument specific credit risk (2)(4) ) ) ) Change in fair value pre-tax loss (2) ) ) ) Interest expense (5) Real estate Change in fair value pre-tax gain (6) Investment funds Change in fair value pre-tax gain (6)(7) — — Dividend income (6) — — (1) None of the change in fair value related to instrument-specific credit risk. (2) Reported in net realized capital gains (losses) on the consolidated statements of operations. (3) Reported in net investment income on the consolidated statements of operations and recorded based on the effective interest rates as determined at the closing of the loan. (4) Estimated based on credit spreads and quality ratings. (5) Reported in operating expenses on the consolidated statements of operations. (6) Reported in net investment income on the consolidated statements of operations. (7) Absent the fair value election, the change in fair value on the investments would be reported in OCI.
Financial Instruments Not Reported at Fair Value (Table)	December 31, 2016 Fair value hierarchy level Carrying amount Fair value Level 1 Level 2 Level 3 (in millions) Assets (liabilities) Mortgage loans $ $ $ — $ — $ Policy loans — — Other investments — Cash and cash equivalents — Investment contracts ) ) — ) ) Short-term debt ) ) — ) — Long-term debt ) ) — ) — Separate account liabilities ) ) — — ) Bank deposits ) ) ) ) — Cash collateral payable ) ) ) — — December 31, 2015 Fair value hierarchy level Carrying amount Fair value Level 1 Level 2 Level 3 (in millions) Assets (liabilities) Mortgage loans $ $ $ — $ — $ Policy loans — — Other investments — Cash and cash equivalents — — Investment contracts ) ) — ) ) Short-term debt ) ) — ) — Long-term debt ) ) — ) ) Separate account liabilities ) ) — — ) Bank deposits ) ) ) ) — Cash collateral payable ) ) ) — —

Statutory Insurance Financial47

Statutory Insurance Financial Information (Tables)	12 Months Ended
	Dec. 31, 2016
Statutory Insurance Financial Information
Statutory Net Income and Statutory Capital and Surplus of Principal Life (Table)	As of or for the year 2016 2015 2014 (in millions) Statutory net income $ $ $ Statutory capital and surplus

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2016
Segment Information
Reconciliation of Assets from Segment to Consolidated (Table)	December 31, 2016 December 31, 2015 (in millions) Assets: Retirement and Income Solutions $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ​ ​ ​ ​ ​ ​ ​ ​ Total consolidated assets $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Reconciliation of Operating Revenues and Pre-tax Operating Earnings (Losses) by Segment (Table)	For the year ended December 31, 2016 2015 2014 (in millions) Operating revenues by segment: Retirement and Income Solutions: Retirement and Income Solutions — Fee $ $ $ Retirement and Income Solutions — Spread ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Retirement and Income Solutions (1) Principal Global Investors (2) Principal International U.S. Insurance Solutions: Specialty benefits insurance Individual life insurance Eliminations ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total U.S. Insurance Solutions Corporate ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total segment operating revenues Net realized capital gains (losses), net of related revenue adjustments ) ) Certain adjustments related to equity method investments ) ) ) Other income on a tax indemnification — — Exited group medical insurance business — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues per consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax operating earnings (losses) by segment: Retirement and Income Solutions $ $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total segment pre-tax operating earnings Pre-tax net realized capital gains (losses), as adjusted (3) ) ) Pre-tax other adjustments (4) ) ) Certain adjustments related to equity method investments and noncontrolling interest ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes per consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Reflects inter-segment revenues of $373.3 million, $424.5 million and $440.1 million for the years ended December 31, 2016, 2015 and 2014, respectively. (2) Reflects inter-segment revenues of $235.7 million, $220.6 million and $206.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. (3) Pre-tax net realized capital gains (losses), as adjusted, is derived as follows: For the year ended 2016 2015 2014 (in millions) Net realized capital gains (losses) $ $ ) $ Certain derivative and hedging-related adjustments ) ) ) Certain market value adjustments to fee revenues ) ) — Certain adjustments related to equity method investments — — Certain adjustments related to sponsored investment funds — Recognition of front-end fee revenue ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses), net of related revenue adjustments ) ) Amortization of deferred acquisition costs and other actuarial balances ) ) ) Capital (gains) losses distributed ) ) Certain market value adjustments of embedded derivatives ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-tax net realized capital gains (losses), as adjusted (a) $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (a) As adjusted before noncontrolling interest capital gains (losses) and net realized capital gains (losses) associated with exited group medical insurance business. (4) For the year ended December 31, 2016, pre-tax other adjustments included the negative effect of one-time costs incurred to extinguish long-term debt. For the year ended December 31, 2015, pre-tax other adjustments included the positive effect of the impact of a court ruling on some uncertain tax positions ($15.1 million) and the negative effect of losses associated with our exited group medical insurance business that did not qualify for discontinued operations accounting treatment under U.S. GAAP ($3.4 million). For the year ended December 31, 2014, pre-tax other adjustments included the negative effect of the impact of (a) a court ruling on some uncertain tax positions ($62.2 million) and (b) the effect of losses accociated with our exited group medical insurance business that did not qualify for discontinued operations accounting treatment under U.S. GAAP ($0.9 million).
Reconciliation of Other Significant Reconciling Items from Segments to Consolidated (Table)	For the year ended 2016 2015 2014 (in millions) Income tax expense (benefit) by segment: Retirement and Income Solutions $ $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total segment income taxes from operating earnings Tax benefit related to net realized capital losses, as adjusted ) ) ) Tax expense (benefit) related to other after-tax adjustments ) ) Certain adjustments related to equity method investments and noncontrolling interest ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total income taxes per consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Reconciliation of Depreciation and Amortization Expense from Segments to Consolidated (Table)	For the year ended 2016 2015 2014 (in millions) Depreciation and amortization expense by segment: Retirement and Income Solutions $ $ $ Principal Global Investors Principal International U.S. Insurance Solutions Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total depreciation and amortization expense included in our consolidated statements of operations $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Stock-Based Compensation Plans
Stock-Based Compensation Disclosures (Table)	For the year ended 2016 2015 2014 (in millions) Compensation cost $ $ $ Related income tax benefit Capitalized as part of an asset
Nonqualified Stock Options Status (Table)	Number of options Weighted- Intrinsic value (in millions) (in millions) Options outstanding as of January 1, 2016 $ Granted Exercised Expired ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding as of December 31, 2016 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options vested or expected to vest as of December 31, 2016 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable as of December 31, 2016 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Nonqualified Stock Options Remaining Contractual Lives and Range of Exercise Prices (Table)	The following is a summary of weighted-average remaining contractual lives for stock options outstanding and the range of exercise prices on the stock options as of December 31, 2016: Range of exercise prices Number of options Weighted- (in millions) $11.07 - $21.69 $21.70 - $32.32 $32.33 - $42.95 $42.96 - $53.58 $53.59 - $64.22 ​ ​ ​ ​ ​ ​ ​ ​ $11.07 - $64.22 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Nonqualified Stock Options Fair Value (Table)	For the year ended Options 2016 2015 2014 Expected volatility % % % Expected term (in years) Risk-free interest rate % % % Expected dividend yield % % % Weighted average estimated fair value $ $ $
Nonvested Performance Share Awards Activity (Table)	Number of Weighted- (in millions) Nonvested performance share awards as of January 1, 2016 $ Granted Vested ​ ​ ​ ​ ​ ​ ​ ​ Nonvested performance share awards as of December 31, 2016 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Nonvested Restricted Stock Units Activity (Table)	Number of Weighted- (in millions) Nonvested restricted stock units as of January 1, 2016 $ Granted Vested ​ ​ ​ ​ ​ ​ ​ ​ Nonvested restricted stock units as of December 31, 2016 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Common Share
Earnings Per Common Share (Table)	For the year ended 2016 2015 2014 (in millions, except per Net income $ $ $ Subtract: Net income attributable to noncontrolling interest Preferred stock dividends — Excess of redemption value over carrying value of preferred shares redeemed — — Adjustments to redemption amounts of redeemable noncontrolling interests — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares outstanding: Basic Dilutive effects: Stock options Restricted stock units Performance share awards ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per common share: Basic $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Quarterly Results of Operatio51

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Results of Operations (Unaudited)
Quarterly Results of Operations (Table)	For the three months ended, December 31 September 30 June 30 March 31 (in millions, except per share data) 2016 Total revenues $ $ $ $ Total expenses Net income Net income available to common stockholders Basic earnings per common share for net income available to common stockholders Diluted earnings per common share for net income available to common stockholders 2015 Total revenues $ $ $ $ Total expenses Net income Net income available to common stockholders Basic earnings per common share for net income available to common stockholders Diluted earnings per common share for net income available to common stockholders

Condensed Consolidating Finan52

Condensed Consolidating Financial Information (Tables)	12 Months Ended
	Dec. 31, 2016
Condensed Consolidating Financial Information
Condensed Consolidating Financial Information, Notes Guarantor (Table)	Condensed Consolidating Statements of Financial Position Principal Principal Life Principal Financial Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ $ $ ) $ Fixed maturities, trading — — Equity securities, available-for-sale — — Equity securities, trading — — Mortgage loans — ) Real estate — — Policy loans — — Investment in unconsolidated entities ) Other investments ) Cash and cash equivalents ) Accrued investment income — ) Premiums due and other receivables — ) Deferred acquisition costs — — Property and equipment — — Goodwill — — Other intangibles — — Separate account assets — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ $ $ ) $ Future policy benefits and claims — ) Other policyholder funds — ) Short-term debt — — — Long-term debt — ) Income taxes currently payable — — ) Deferred income taxes — ) Separate account liabilities — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive income (loss) ) ) ) ) Treasury stock, at cost ) — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Financial Position Principal Principal Life Principal Financial Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ $ $ ) $ Fixed maturities, trading — — Equity securities, available-for-sale — — Equity securities, trading — — Mortgage loans — ) Real estate — — Policy loans — — Investment in unconsolidated entities ) Other investments ) Cash and cash equivalents ) Accrued investment income — ) Premiums due and other receivables — ) Deferred acquisition costs — — Property and equipment — — Goodwill — — Other intangibles — — Separate account assets — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ $ $ ) $ Future policy benefits and claims — ) Other policyholder funds — ) Short-term debt — — — Long-term debt — ) Income taxes currently payable — — ) Deferred income taxes — ) Separate account liabilities — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive income (loss) ) ) ) ) Treasury stock, at cost ) — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Life Principal Financial Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains, excluding impairment losses on available-for-sale securities — Net other-than-temporary impairment losses on available-for-sale securities — ) ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — ) Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) Income taxes (benefits) ) ) Equity in the net income (loss) of subsidiaries ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Life Principal Financial Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains (losses), excluding impairment losses on available-for-sale securities — ) — ) Net other-than-temporary impairment losses on available-for-sale securities — ) ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified from other comprehensive income — ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — ) Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) Income taxes (benefits) ) ) Equity in the net income of subsidiaries ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — Excess of redemption value over carrying value of preferred shares redeemed — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive loss ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Life Principal Financial Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains (losses), excluding impairment losses on available-for-sale securities — ) — Net other-than-temporary impairment (losses) recoveries on available-for-sale securities — ) — Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — ) Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) Income taxes (benefits) ) ) ) Equity in the net income (loss) of subsidiaries ) ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income (loss) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Life Principal Financial Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — ) ) ) Sales — — Maturities — — Mortgage loans acquired or originated — ) ) ) Mortgage loans sold or repaid — ) Real estate acquired — — ) — ) Net purchases of property and equipment ) ) ) — ) Dividends and returns of capital received from unconsolidated entities ) — Net change in other investments ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — ) — — ) Excess tax benefits from share-based payment arrangements — Purchase of subsidiary shares from noncontrolling interest — — ) ) Sale of subsidiary shares to noncontrolling interest — — ) — Dividends to common stockholders ) — — — ) Issuance of long-term debt — Principal repayments of long-term debt ) — ) ) ) Net repayments of short-term borrowings — — ) — ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — Investment contract withdrawals — ) ) — ) Net increase in banking operation deposits — — — Other — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) financing activities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Life Principal Financial Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ $ Investing activities Available-for-sale securities: Purchases — ) ) — ) Sales — ) Maturities — — Mortgage loans acquired or originated — ) ) ) Mortgage loans sold or repaid — ) Real estate acquired — ) ) — ) Net purchases of property and equipment — ) ) — ) Purchase of interests in subsidiaries, net of cash acquired — — ) — ) Dividends and returns of capital received from (contributed to) unconsolidated entities ) ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — ) — — ) Excess tax benefits from share-based payment arrangements — Purchase of subsidiary shares from noncontrolling interest — — ) ) Sale of subsidiary shares to noncontrolling interest — — ) — Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Preferred stock redemption ) — — — ) Issuance of long-term debt — ) Principal repayments of long-term debt — — ) ) Net proceeds from short-term borrowings — — — Dividends and capital paid to parent — ) ) — Investment contract deposits — — Investment contract withdrawals — ) ) — ) Net increase in banking operation deposits — — — Other — ) — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase in cash and cash equivalents Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Life Principal Financial Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — ) ) ) Sales — — Maturities — — Mortgage loans acquired or originated — ) ) ) Mortgage loans sold or repaid — ) Real estate acquired — ) ) — ) Net purchases of property and equipment — ) ) — ) Dividends and returns of capital received from unconsolidated entities ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — ) — — ) Excess tax benefits from share-based payment arrangements — Purchase of subsidiary shares from noncontrolling interest — — ) ) Sale of subsidiary shares to noncontrolling interest — — ) — Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Issuance of long-term debt — — ) Principal repayments of long-term debt — ) ) ) Net repayments of short-term borrowings — — ) — ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — Investment contract withdrawals — ) ) — ) Net increase in banking operation deposits — — — Other — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) ) Cash and cash equivalents at beginning of period ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Condensed Consolidating Financial Information, Shelf Registration Guarantor (Table)	Condensed Consolidating Statements of Financial Position Principal Principal Principal Life Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ — $ $ — $ Fixed maturities, trading — — — Equity securities, available-for-sale — — — Equity securities, trading — — — Mortgage loans — — — Real estate — — — Policy loans — — — Investment in unconsolidated entities ) Other investments — Cash and cash equivalents ) Accrued investment income — — Premiums due and other receivables — ) Deferred acquisition costs — — — Property and equipment — — — Goodwill — — — Other intangibles — — — Separate account assets — — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ — $ $ — $ Future policy benefits and claims — — — Other policyholder funds — — — Short-term debt — — ) Long-term debt ) ) Income taxes currently payable — — ) Deferred income taxes — — ) Separate account liabilities — — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive loss ) ) ) ) Treasury stock, at cost ) — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Financial Position Principal Principal Principal Life Eliminations Principal (in millions) Assets Fixed maturities, available-for-sale $ — $ — $ $ — $ Fixed maturities, trading — — — Equity securities, available-for-sale — — — Equity securities, trading — — — Mortgage loans — — — Real estate — — — Policy loans — — — Investment in unconsolidated entities ) Other investments — Cash and cash equivalents ) Accrued investment income — — — Premiums due and other receivables — ) Deferred acquisition costs — — — Property and equipment — — — Goodwill — — — Other intangibles — — — Separate account assets — — — Other assets ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total assets $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities Contractholder funds $ — $ — $ $ — $ Future policy benefits and claims — — — Other policyholder funds — — — Short-term debt — — ) Long-term debt ) Income taxes currently payable — ) Deferred income taxes — — ) Separate account liabilities — — — Other liabilities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities ) Redeemable noncontrolling interest — — — Stockholders' equity Common stock — ) Additional paid-in capital ) Retained earnings ) Accumulated other comprehensive loss ) ) ) ) Treasury stock, at cost ) — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity attributable to PFG ) Noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stockholders' equity ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities and stockholders' equity $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Principal Life Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ — $ $ — $ Fees and other revenues — ) Net investment income Net realized capital gains (losses), excluding impairment losses on available-for-sale securities — ) Net other-than-temporary impairment losses on available-for-sale securities — — ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to other comprehensive income — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains (losses) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Benefits, claims and settlement expenses — — — Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) Income taxes (benefits) ) ) — Equity in the net income of subsidiaries — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Principal Life Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ — $ $ — $ Fees and other revenues — ) Net investment income Net realized capital losses, excluding impairment losses on available-for-sale securities — ) ) — ) Net other-than-temporary impairment losses on available-for-sale securities — — ) — ) Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified from other comprehensive income — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital losses — ) ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues Expenses Benefits, claims and settlement expenses — — — Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) Income taxes (benefits) ) ) — Equity in the net income of subsidiaries — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — Excess of redemption value over carrying value of preferred shares redeemed — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive loss ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Operations Principal Principal Principal Life Eliminations Principal (in millions) Revenues Premiums and other considerations $ — $ — $ $ — $ Fees and other revenues — ) Net investment income ) Net realized capital gains, excluding impairment losses on available-for-sale securities — ) Net other-than-temporary impairment recoveries on available-for-sale securities — — — Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified from other comprehensive income — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net impairment losses on available-for-sale securities — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net realized capital gains — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ) Expenses Benefits, claims and settlement expenses — — — Dividends to policyholders — — — Operating expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before income taxes ) ) ) Income taxes (benefits) ) ) — Equity in the net income of subsidiaries — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ) Net income attributable to noncontrolling interest — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to PFG ) Preferred stock dividends — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income available to common stockholders $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income $ $ $ $ ) $ Other comprehensive income (loss) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Comprehensive income $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Principal Life Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — — ) — ) Sales — — — Maturities — — — Mortgage loans acquired or originated — — ) — ) Mortgage loans sold or repaid — — — Real estate acquired — — ) — ) Net purchases of property and equipment ) — ) — ) Dividends and returns of capital received from unconsolidated entities — ) — Net change in other investments ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — — ) — ) Excess tax benefits from share-based payment arrangements — — Purchase of subsidiary shares from noncontrolling interest — — ) — ) Dividends to common stockholders ) — — — ) Issuance of long-term debt ) Principal repayments of long-term debt ) ) ) ) Net repayments of short-term borrowings — — ) ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — — Investment contract withdrawals — — ) — ) Net increase in banking operation deposits — — — Other — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) financing activities ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Principal Life Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ $ $ ) $ Investing activities Available-for-sale securities: Purchases — — ) — ) Sales — — — Maturities — — — Mortgage loans acquired or originated — — ) — ) Mortgage loans sold or repaid — — — Real estate acquired — — ) — ) Net purchases of property and equipment — — ) — ) Purchase of interests in subsidiaries, net of cash acquired — — ) — ) Dividends and returns of capital received from unconsolidated entities — ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — — ) — ) Excess tax benefits from share-based payment arrangements — — Purchase of subsidiary shares from noncontrolling interest — — ) — ) Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Preferred stock redemption ) — — — ) Issuance of long-term debt ) Principal repayments of long-term debt — — ) ) Net proceeds from short-term borrowings — — Dividends and capital paid to parent — ) ) — Investment contract deposits — — — Investment contract withdrawals — — ) — ) Net increase in banking operation deposits — — — Other — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Condensed Consolidating Statements of Cash Flows Principal Principal Principal Life Eliminations Principal (in millions) Operating activities Net cash provided by (used in) operating activities $ ) $ ) $ $ ) $ Investing activities Available-for-sale securities: Purchases — — ) — ) Sales — — — Maturities — — — Mortgage loans acquired or originated — — ) — ) Mortgage loans sold or repaid — — — Real estate acquired — — ) — ) Net purchases of property and equipment — — ) — ) Dividends and returns of capital received from unconsolidated entities — ) — Net change in other investments ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash provided by (used in) investing activities ) ) ) Financing activities Issuance of common stock — — — Acquisition of treasury stock ) — — — ) Proceeds from financing element derivatives — — — Payments for financing element derivatives — — ) — ) Excess tax benefits from share-based payment arrangements — — Purchase of subsidiary shares from noncontrolling interest — — ) — ) Dividends to common stockholders ) — — — ) Dividends to preferred stockholders ) — — — ) Issuance of long-term debt — — — Principal repayments of long-term debt — — ) — ) Net repayments of short-term borrowings — — ) ) Dividends and capital paid to parent — ) ) — Investment contract deposits — — — Investment contract withdrawals — — ) — ) Net increase in banking operation deposits — — — Other — — ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net cash used in financing activities ) ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash and cash equivalents ) ) ) Cash and cash equivalents at beginning of period ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents at end of period $ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Nature of Operations and Sign53

Nature of Operations and Significant Accounting Policies - Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)Counterparty	Dec. 31, 2015USD ($)Counterparty	Dec. 31, 2014USD ($)
Cash and Cash Equivalents
Maximum maturity period when purchased for investments to be included in cash and cash equivalents	3 months
Investments
Real estate held for sale	$ 130.7	$ 169.7
Contractholder and Policyholder Liabilities
Participating business as a percentage of life insurance in force (as a percent)	8.00%	9.00%	11.00%
Participating business as a percentage of life insurance policies in force (as a percent)	33.00%	36.00%	40.00%
Participating business as a percentage of life insurance premiums (as a percent)	31.00%	36.00%	40.00%
Long-Term Debt
Minimum maturity period at date of issuance for debt to be classified as long-term	1 year
Reinsurance
Net ceded reinsurance recoverables related to claims received	$ 412.8	$ 397.5
Amount of net ceded reinsurance recoverables related to claims received with five largest ceded reinsurers	$ 390.5	$ 379.4
Percentage of net ceded reinsurance recoverables related to claims received with five largest ceded reinsurers (as a percent)	95.00%	95.00%
Number of largest ceded reinsurers | Counterparty	5	5
Total amount recoverable from reinsurers	$ 837.1	$ 857.3
Premiums and other considerations:
Premiums and other considerations, Direct	5,753.8	5,710.8	$ 4,123.7
Premiums and other considerations, Assumed	1.7	1.9	2.1
Premiums and other considerations, Ceded	(456.4)	(402.4)	(402.9)
Premiums and other considerations	5,299.1	5,310.3	3,722.9
Benefits, claims and settlement expenses:
Benefits, claims and settlement expenses, Direct	7,202.5	7,196.7	5,532.5
Benefits, claims and settlement expenses, Assumed	28.1	28.7	30.7
Benefits, claims and settlement expenses, Ceded	(317.4)	(527.7)	(332.2)
Benefits, claims and settlement expenses	6,913.2	6,697.7	$ 5,231
Separate Accounts
Separate account that primarily includes shares of Principal Financial Group, Inc. stock that were allocated and issued to eligible participants of qualified employee benefit plans as part of the 2001 demutualization	$ 158.4	$ 158.2

Goodwill and Other Intangible54

Goodwill and Other Intangible Assets - Changes in Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Changes in Goodwill
Beginning balance, Goodwill	$ 1,009	$ 1,007.4
Goodwill from acquisitions		104.8
Foreign currency, Goodwill	11.8	(103.2)
Ending balance, Goodwill	1,020.8	1,009
Retirement and Income Solutions
Changes in Goodwill
Beginning balance, Goodwill	57.4	57.4
Ending balance, Goodwill	57.4	57.4
Principal Global Investors
Changes in Goodwill
Beginning balance, Goodwill	252.1	252.4
Goodwill from acquisitions		3.1
Foreign currency, Goodwill	(9.6)	(3.4)
Ending balance, Goodwill	242.5	252.1
Principal International
Changes in Goodwill
Beginning balance, Goodwill	642.9	641
Goodwill from acquisitions		101.7
Foreign currency, Goodwill	21.4	(99.8)
Ending balance, Goodwill	664.3	642.9
U.S. Insurance Solutions
Changes in Goodwill
Beginning balance, Goodwill	56.6	56.6
Ending balance, Goodwill	$ 56.6	$ 56.6

Goodwill and Other Intangible55

Goodwill and Other Intangible Assets - Goodwill Acquired (Details) - USD ($) $ in Millions	Sep. 01, 2015	Dec. 31, 2015
Goodwill and Other Intangible Assets
Goodwill from acquisitions		$ 104.8
AXA pension business
Goodwill and Other Intangible Assets
Purchase price of acquired business	$ 335.5
Goodwill from acquisitions	$ 104.8
Distribution agreements | AXA pension business
Goodwill and Other Intangible Assets
Exclusive distribution agreement period	15 years
Finite lived intangible assets acquired	$ 53
Finite lived intangible asset, useful life	15 years
Customer relationships | AXA pension business
Goodwill and Other Intangible Assets
Finite lived intangible assets acquired	$ 138
Finite lived intangible asset, useful life	30 years

Goodwill and Other Intangible56

Goodwill and Other Intangible Assets - Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite Lived Intangible Asset Disclosures
Weighted average remaining expected life of finite lived intangible assets	16 years
Gross carrying amount	$ 756.2	$ 766.7
Accumulated amortization	228.7	198.1
Net carrying amount	527.5	568.6
Finite lived intangible assets fully amortized during the period	2.2	0.5	$ 118.6
Other Finite Lived Intangible Assets
Amortization expense for intangible assets with finite useful lives	44.5	42.5	$ 49.9
Estimated amortization expense for the next five years
Year 1: Finite lived intangible assets amortization	44.7
Year 2: Finite lived intangible assets amortization	44.1
Year 3: Finite lived intangible assets amortization	43
Year 4: Finite lived intangible assets amortization	42.3
Year 5: Finite lived intangible assets amortization	$ 39.6
Brazil mutual fund company
Finite Lived Intangible Asset Disclosures
Gross carrying amount		11.5
Accumulated amortization		3.2
Brazil mutual fund company | Operating expense
Finite Lived Intangible Asset Disclosures
Other finite lived intangible assets impairment		$ 8.3

Goodwill and Other Intangible57

Goodwill and Other Intangible Assets - Indefinite-Lived Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016
Indefinite Lived Intangible Assets
Net carrying amount of unamortized indefinite lived intangible assets	$ 790.6	$ 797.8
WM Advisors, Inc.
Indefinite Lived Intangible Assets
Net carrying amount of unamortized indefinite lived intangible assets	608	$ 608
Operating expense | Brazil mutual fund company
Indefinite Lived Intangible Assets
Indefinite lived intangible asset impairment	$ 14.7

Variable Interest Entities - Re

Variable Interest Entities - Recent Accounting Pronouncement (Details) - USD ($) $ in Millions	Jan. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Consolidated assets		$ 228,014.3	$ 218,660.3
Consolidated liabilities		217,623	209,197.2
Redeemable noncontrolling interest		$ 97.5	$ 85.7	$ 58	$ 247.2
New Accounting Pronouncement | Accounting Standards Update 2015-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deconsolidated assets	$ 8,600
Deconsolidated liabilities	8,600
Cumulative effect on retained earnings	0
Consolidated assets	180.1
Consolidated liabilities	0.6
Redeemable noncontrolling interest	$ 179.5

Variable Interest Entities - Co

Variable Interest Entities - Consolidated VIEs (Details) $ in Millions	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 37,298.4	$ 34,702.2
Total liabilities	$ 36,504.3	34,028.3
Grantor trusts
Consolidated Variable Interest Entity disclosures
Number of consolidated variable interest entities | item	3
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 233.3	257.9
Total liabilities	$ 212.3	231.8
Collateralized private investment vehicle
Consolidated Variable Interest Entity disclosures
Number of entities for which the reporting entity acts as primary beneficiary | item	1
Carrying amounts of consolidated VIE assets and liabilities
Total assets	$ 82.4	100.4
Total liabilities	61.5	85.9
Commercial mortgage-backed securities VIE
Carrying amounts of consolidated VIE assets and liabilities
Total assets	12.5	18.4
Mandatory retirement savings
Carrying amounts of consolidated VIE assets and liabilities
Total assets	36,526.7	33,941.3
Total liabilities	36,202.8	33,639.3
Real estate VIE
Carrying amounts of consolidated VIE assets and liabilities
Total assets	329.2	384.2
Total liabilities	26.8	$ 71.3
Sponsored investment funds
Carrying amounts of consolidated VIE assets and liabilities
Total assets	114.3
Total liabilities	0.9
Redeemable noncontrolling interest	$ 58.8

Variable Interest Entities - Un

Variable Interest Entities - Unconsolidated VIEs (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Money Market Funds
Total assets of unconsolidated money market mutual funds	$ 800	$ 1,300
Other investments: Other limited partnership and fund interests
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	654.6	255.6
Maximum exposure to loss	1,127.8	255.6
Available-for-sale | Corporate debt securities
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	368.4	453.4
Maximum exposure to loss	298.6	359.8
Available-for-sale | Residential mortgage-backed pass-through securities
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	2,834.7	2,627.5
Maximum exposure to loss	2,798	2,549.4
Available-for-sale | Commercial mortgage-backed securities
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	4,096.5	3,919.8
Maximum exposure to loss	4,153.2	3,932.5
Available-for-sale | Collateralized debt obligations
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	758.6	667.5
Maximum exposure to loss	780.1	692.7
Available-for-sale | Other debt obligations
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	5,036.1	4,530.8
Maximum exposure to loss	5,048.9	4,527.3
Trading | Residential mortgage-backed pass-through securities
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	19.9	25.9
Maximum exposure to loss	19.9	25.9
Trading | Commercial mortgage-backed securities
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	1.9	2.3
Maximum exposure to loss	1.9	2.3
Trading | Collateralized debt obligations
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	10.6	35.1
Maximum exposure to loss	10.6	$ 35.1
Trading | Equity securities
Unconsolidated Variable Interest Entity disclosures
Asset carrying value	68.3
Maximum exposure to loss	$ 68.3

Investments - Fixed Maturities

Investments - Fixed Maturities and Equity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fixed maturities
Available-for-sale securities disclosures
Amortized cost	$ 53,184.2	$ 48,674.3
Gross unrealized gains	2,310.7	2,115.4
Gross unrealized losses	648.8	823.2
Fair value	54,846.1	49,966.5
Other-than-temporary impairments in AOCI	146.4	146.1
Net unrealized gains (losses) on impaired fixed maturities, available-for-sale related to changes in fair value subsequent to the impairment date	120.9	131.5
U.S. government and agencies
Available-for-sale securities disclosures
Amortized cost	1,426.7	1,488.4
Gross unrealized gains	17.2	23.4
Gross unrealized losses	10.9	8.3
Fair value	1,433	1,503.5
Non-U.S. governments
Available-for-sale securities disclosures
Amortized cost	781.7	669.8
Gross unrealized gains	119.3	128.5
Gross unrealized losses	7.4	5
Fair value	893.6	793.3
States and political subdivisions
Available-for-sale securities disclosures
Amortized cost	5,463.9	4,501.8
Gross unrealized gains	192.4	234.7
Gross unrealized losses	87.1	19.4
Fair value	5,569.2	4,717.1
Other-than-temporary impairments in AOCI	1.1
Corporate debt securities
Available-for-sale securities disclosures
Amortized cost	32,699.7	30,245.5
Gross unrealized gains	1,843.5	1,532.9
Gross unrealized losses	350.8	638.2
Fair value	34,192.4	31,140.2
Other-than-temporary impairments in AOCI	17.2	5.9
Residential mortgage-backed pass-through securities
Available-for-sale securities disclosures
Amortized cost	2,798	2,549.4
Gross unrealized gains	67.3	90
Gross unrealized losses	30.6	11.9
Fair value	2,834.7	2,627.5
Commercial mortgage-backed securities
Available-for-sale securities disclosures
Amortized cost	4,153.2	3,932.5
Gross unrealized gains	31.2	65.3
Gross unrealized losses	87.9	78
Fair value	4,096.5	3,919.8
Other-than-temporary impairments in AOCI	77.5	80.7
Collateralized debt obligations
Available-for-sale securities disclosures
Amortized cost	780.1	692.7
Gross unrealized gains	2.8	1.4
Gross unrealized losses	24.3	26.6
Fair value	758.6	667.5
Other-than-temporary impairments in AOCI	0.3	1.3
Other debt obligations
Available-for-sale securities disclosures
Amortized cost	5,080.9	4,594.2
Gross unrealized gains	37	39.2
Gross unrealized losses	49.8	35.8
Fair value	5,068.1	4,597.6
Other-than-temporary impairments in AOCI	50.3	58.2
Equity securities
Available-for-sale securities disclosures
Amortized cost	104.9	111.2
Gross unrealized gains	4.9	7.5
Gross unrealized losses	10.9	14.2
Fair value	$ 98.9	$ 104.5

Investments - Amortization by E

Investments - Amortization by Expected Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Amortized cost of fixed maturities available-for-sale
Due in one year or less	$ 3,216.1
Due after one year through five years	12,286.4
Due after five years through ten years	8,572.8
Due after ten years	16,296.7
Subtotal	40,372
Mortgage-backed and other asset-backed securities	12,812.2
Total	53,184.2
Fair value of fixed maturities available-for-sale
Due in one year or less	3,230.2
Due after one year through five years	12,677.4
Due after five years through ten years	8,788.4
Due after ten years	17,392.2
Subtotal	42,088.2
Mortgage-backed and other asset-backed securities	12,757.9
Total	$ 54,846.1	$ 49,966.5

Investments - Net Investment In

Investments - Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Major categories of net investment income
Gross investment income (loss)	$ 3,380.9	$ 3,129.1	$ 3,334.8
Investment expenses	(84.4)	(77)	(76.9)
Net investment income (loss)	3,296.5	3,052.1	3,257.9
Mortgage loans
Major categories of net investment income
Gross investment income (loss)	573.9	575.1	630.9
Real estate
Major categories of net investment income
Gross investment income (loss)	127.9	97.1	103.8
Policy loans
Major categories of net investment income
Gross investment income (loss)	46.3	46.3	49.4
Cash and cash equivalents
Major categories of net investment income
Gross investment income (loss)	14.2	8.5	6.5
Derivatives
Major categories of net investment income
Gross investment income (loss)	(36.1)	(66.6)	(88)
Other investment types
Major categories of net investment income
Gross investment income (loss)	329.2	265.3	252.1
Available-for-sale | Fixed maturities
Major categories of net investment income
Gross investment income (loss)	2,253.8	2,131.8	2,283.8
Available-for-sale | Equity securities
Major categories of net investment income
Gross investment income (loss)	20.1	15	7
Trading | Fixed maturities
Major categories of net investment income
Gross investment income (loss)	20.2	21.4	27.9
Trading | Equity securities
Major categories of net investment income
Gross investment income (loss)	$ 31.4	$ 35.2	$ 61.4

Investments - Net Realized Capi

Investments - Net Realized Capital Gains and Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Major components of net realized capital gains (losses) on investments
Net impairment (losses) recoveries on available-for-sale securities	$ (98.4)	$ (30.2)	$ (78)
Net realized capital gains (losses)	171.1	(51.1)	14.7
Proceeds from sales of investments
Proceeds from sales of investments in fixed maturities, available-for-sale	1,916.9	1,537.5	2,251.2
Mortgage loans
Major components of net realized capital gains (losses) on investments
Realized capital gains (losses)	4.5	(0.1)	(9.4)
Derivatives
Major components of net realized capital gains (losses) on investments
Realized capital gains (losses)	210.1	38.1	13.1
Other investment types
Major components of net realized capital gains (losses) on investments
Realized capital gains (losses)	35.9	1.5	20.4
Available-for-sale | Fixed maturities
Major components of net realized capital gains (losses) on investments
Gross gains	74.6	20.9	61.3
Gross losses	(28.6)	(6.7)	(24.1)
Net impairment (losses) recoveries on available-for-sale securities	(96.7)	(30.5)	(88)
Hedging, net	(37.9)	(58.3)	(21.5)
Available-for-sale | Equity securities
Major components of net realized capital gains (losses) on investments
Gross gains		1.2	0.2
Gross losses		(1.8)	(0.2)
Net impairment (losses) recoveries on available-for-sale securities	(1.7)	0.3	10
Trading | Fixed maturities
Major components of net realized capital gains (losses) on investments
Realized gains (losses) on trading securities	4.1	(12.3)	31.2
Trading | Equity securities
Major components of net realized capital gains (losses) on investments
Realized gains (losses) on trading securities	$ 6.8	$ (3.4)	$ 21.7

Investments - Other-Than-Tempor

Investments - Other-Than-Temporary Impairments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other-than-temporary impairment losses, net of recoveries
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	$ (98.8)	$ (0.8)	$ 23.8
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income	0.4	(29.4)	(101.8)
Net impairment (losses) recoveries on available-for-sale securities	(98.4)	(30.2)	(78)
Fixed maturities
Other-than-temporary impairment losses, net of recoveries
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	(97.1)	(1.1)	13.8
Equity securities
Other-than-temporary impairment losses, net of recoveries
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	$ (1.7)	$ 0.3	$ 10

Investments - Accumulated Credi

Investments - Accumulated Credit Losses for Fixed Maturities with Bifurcated Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other-Than-Temporary Impairment Credit Losses Recognized in Net Income - Rollforward
Beginning balance	$ (131.5)	$ (144.4)	$ (235.4)
Credit losses for which an other-than-temporary impairment was not previously recognized	(43.4)	(6.1)	(11.3)
Credit losses for which an other-than-temporary impairment was previously recognized	(31.7)	(13.8)	(67.4)
Reduction for credit losses previously recognized on fixed maturities now sold, paid down or intended to be sold	60.5	24.7	163.1
Net reduction (increase) for positive changes in cash flows expected to be collected and amortization	6.4	7.5	6.6
Foreign currency translation adjustment	(0.2)	0.6
Ending balance	$ (139.9)	$ (131.5)	$ (144.4)

Investments - Gross Unrealized

Investments - Gross Unrealized Losses for Fixed Maturities and Equity Securities (Details) $ in Millions	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)item
Fixed maturities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	$ 14,955.3	$ 14,421.5
Less than twelve months, Gross unrealized losses	396.6	395.9
Greater than or equal to twelve months, Fair value	2,511.1	2,453
Greater than or equal to twelve months, Gross unrealized losses	252.2	427.3
Total, Fair value	17,466.4	16,874.5
Total, Gross unrealized losses	648.8	823.2
U.S. government and agencies
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	570.3	590.4
Less than twelve months, Gross unrealized losses	10.9	7.6
Greater than or equal to twelve months, Fair value	8.2	40.5
Greater than or equal to twelve months, Gross unrealized losses		0.7
Total, Fair value	578.5	630.9
Total, Gross unrealized losses	10.9	8.3
Non-U.S. governments
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	198	86.3
Less than twelve months, Gross unrealized losses	5.4	3.1
Greater than or equal to twelve months, Fair value	12.2	16.1
Greater than or equal to twelve months, Gross unrealized losses	2	1.9
Total, Fair value	210.2	102.4
Total, Gross unrealized losses	7.4	5
States and political subdivisions
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	2,229.4	692
Less than twelve months, Gross unrealized losses	86.6	19
Greater than or equal to twelve months, Fair value	4.8	6.5
Greater than or equal to twelve months, Gross unrealized losses	0.5	0.4
Total, Fair value	2,234.2	698.5
Total, Gross unrealized losses	87.1	19.4
Corporate debt securities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	6,559.7	7,975.7
Less than twelve months, Gross unrealized losses	189.2	309.3
Greater than or equal to twelve months, Fair value	1,285.6	1,375
Greater than or equal to twelve months, Gross unrealized losses	161.6	328.9
Total, Fair value	7,845.3	9,350.7
Total, Gross unrealized losses	350.8	638.2
Residential mortgage-backed pass-through securities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	1,265.6	656.7
Less than twelve months, Gross unrealized losses	29.8	6.7
Greater than or equal to twelve months, Fair value	16	147.9
Greater than or equal to twelve months, Gross unrealized losses	0.8	5.2
Total, Fair value	1,281.6	804.6
Total, Gross unrealized losses	30.6	11.9
Commercial mortgage-backed securities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	1,637.2	1,480.8
Less than twelve months, Gross unrealized losses	41	27.3
Greater than or equal to twelve months, Fair value	612.5	299.5
Greater than or equal to twelve months, Gross unrealized losses	46.9	50.7
Total, Fair value	2,249.7	1,780.3
Total, Gross unrealized losses	87.9	78
Collateralized debt obligations
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	265.7	426.9
Less than twelve months, Gross unrealized losses	0.9	3.8
Greater than or equal to twelve months, Fair value	195.6	164
Greater than or equal to twelve months, Gross unrealized losses	23.4	22.8
Total, Fair value	461.3	590.9
Total, Gross unrealized losses	24.3	26.6
Other debt obligations
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	2,229.4	2,512.7
Less than twelve months, Gross unrealized losses	32.8	19.1
Greater than or equal to twelve months, Fair value	376.2	403.5
Greater than or equal to twelve months, Gross unrealized losses	17	16.7
Total, Fair value	2,605.6	2,916.2
Total, Gross unrealized losses	49.8	35.8
Equity securities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	18.2	0.8
Less than twelve months, Gross unrealized losses	0.4	1
Greater than or equal to twelve months, Fair value	35.4	32.7
Greater than or equal to twelve months, Gross unrealized losses	10.5	13.2
Total, Fair value	53.6	33.5
Total, Gross unrealized losses	10.9	14.2
Principal Life Insurance Company | Fixed maturities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Less than twelve months, Fair value	14,549.4	13,673.9
Less than twelve months, Gross unrealized losses	384.6	376.3
Greater than or equal to twelve months, Fair value	2,369.5	2,306.1
Greater than or equal to twelve months, Gross unrealized losses	230.5	400.7
Total, Fair value	16,918.9	15,980
Total, Gross unrealized losses	$ 615.1	$ 777
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure
Available-for-sale Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less Than Twelve Months | item	1,911	1,725
Available-for-sale Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Twelve Months or Longer | item	453	404
Available-for-sale Securities in Unrealized Loss Position, Aggregate Losses On Investment Grade Investments, Less Than Twelve Months	$ 374.1	$ 298.1
Available-for-sale Securities in Unrealized Loss Positions, Qualitative Disclosure, Percent Investment Grade (as a percent)	94.00%	87.00%
Available-for-sale Securities in Unrealized Loss Positions, Qualitative Disclosure, Average Price (percent of carrying value to amortized cost) | item	96	95
Available-for-sale Securities in Unrealized Loss Positions, Percent Investment Grade, Less Than Twelve Months (as a percent)	98.00%	90.00%
Available-for-sale Securities in Unrealized Loss Positions, Average Price, Less Than Twelve Months (percent of carrying value to amortized cost) | item	97	97
Available-for-sale Securities in Unrealized Loss Positions, Average Price, Twelve Months or Longer (percent of carrying value to amortized cost) | item	91	85
Principal Life Insurance Company | Corporate debt securities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Greater than or equal to twelve months, Gross unrealized losses	$ 141.9	$ 304.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure
Available-for-sale Securities in Unrealized Loss Positions, Average Price, Twelve Months or Longer (percent of carrying value to amortized cost) | item	89	80
Principal Life Insurance Company | Commercial mortgage-backed securities
Gross Unrealized Losses for Fixed Maturities and Equity Securities
Greater than or equal to twelve months, Gross unrealized losses	$ 46.9	$ 50.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure
Available-for-sale Securities in Unrealized Loss Positions, Average Price, Twelve Months or Longer (percent of carrying value to amortized cost) | item	93	86

Investments - Net Unrealized Ga

Investments - Net Unrealized Gains and Losses on Available-for-Sale Securities and Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Net Unrealized Gains and Losses on Available-for-Sale Securities and Derivative Instruments
Net unrealized gains (losses) on fixed maturities, available-for-sale	$ 1,727.8	$ 1,376
Noncredit component of impairment losses on fixed maturities, available-for-sale	(146.4)	(146.1)
Net unrealized gains (losses) on equity securities, available-for-sale	(6)	(6.7)
Adjustments for assumed changes in amortization patterns	(121.9)	(127)
Adjustments for assumed changes in policyholder liabilities	(469.2)	(309.7)
Net unrealized gains (losses) on derivative instruments	186.5	181.6
Net unrealized gains (losses) on equity method subsidiaries and noncontrolling interest adjustments	68	98
Provision for deferred income tax benefits (taxes)	(411.8)	(350.2)
Net unrealized gains (losses) on available-for-sale securities and derivative instruments	$ 827	$ 715.9

Investments - Mortgage Loans (D

Investments - Mortgage Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 13,275.1	$ 12,391	$ 11,868.1
Mortgage loan valuation allowance	(44.9)	(51.6)	(56.5)	$ (69.8)
Mortgage loans, Total carrying value	13,230.2	12,339.4
Commercial mortgage loans
Mortgage loan disclosures
Mortgage loans, Total amortized cost	12,055.2	11,265.3	10,723.8
Mortgage loan valuation allowance	(27.4)	(27.5)	(26.9)	(28.7)
Mortgage loans, purchased	163.3	223.4	59.5
Mortgage loans, sold	$ 0.3	$ 21.6	2.3
Percent of mortgage loans (as a percent)	100.00%	100.00%
Commercial mortgage loans | Office
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 4,417.6	$ 4,010
Percent of mortgage loans (as a percent)	36.60%	35.60%
Commercial mortgage loans | Retail
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 2,671.1	$ 2,521.6
Percent of mortgage loans (as a percent)	22.20%	22.40%
Commercial mortgage loans | Industrial
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 1,802.4	$ 1,840.9
Percent of mortgage loans (as a percent)	15.00%	16.30%
Commercial mortgage loans | Apartments
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 2,741.4	$ 2,474.2
Percent of mortgage loans (as a percent)	22.70%	22.00%
Commercial mortgage loans | Hotel
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 260.7	$ 320.5
Percent of mortgage loans (as a percent)	2.20%	2.70%
Commercial mortgage loans | Mixed use/other
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 162	$ 98.1
Percent of mortgage loans (as a percent)	1.30%	1.00%
Commercial mortgage loans | New England
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 532.1	$ 509.4
Percent of mortgage loans (as a percent)	4.40%	4.50%
Commercial mortgage loans | Middle Atlantic
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 3,317.3	$ 3,075.6
Percent of mortgage loans (as a percent)	27.50%	27.30%
Commercial mortgage loans | East North Central
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 652.6	$ 451.8
Percent of mortgage loans (as a percent)	5.40%	4.00%
Commercial mortgage loans | West North Central
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 185.6	$ 264.3
Percent of mortgage loans (as a percent)	1.50%	2.30%
Commercial mortgage loans | South Atlantic
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 2,189.5	$ 2,072.7
Percent of mortgage loans (as a percent)	18.20%	18.40%
Commercial mortgage loans | East South Central
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 239.3	$ 215.1
Percent of mortgage loans (as a percent)	2.00%	1.90%
Commercial mortgage loans | West South Central
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 1,211.7	$ 1,120.6
Percent of mortgage loans (as a percent)	10.10%	9.90%
Commercial mortgage loans | Mountain
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 932.6	$ 898.8
Percent of mortgage loans (as a percent)	7.70%	8.00%
Commercial mortgage loans | Pacific
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 2,707.2	$ 2,614.1
Percent of mortgage loans (as a percent)	22.50%	23.20%
Commercial mortgage loans | International
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 87.3	$ 42.9
Percent of mortgage loans (as a percent)	0.70%	0.50%
Residential mortgage loans
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 1,219.9	$ 1,125.7	1,144.3
Mortgage loan valuation allowance	(17.5)	(24.1)	(29.6)	$ (41.1)
Mortgage loans, purchased	290.3	295.3	184.8
Mortgage loans, sold	48.4	79.3	$ 95.9
Home equity
Mortgage loan disclosures
Mortgage loans, Total amortized cost	165.6	218.8
First liens
Mortgage loan disclosures
Mortgage loans, Total amortized cost	$ 1,054.3	$ 906.9

Investments - Mortgage Loan Cre

Investments - Mortgage Loan Credit Monitoring (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	$ 13,275.1	$ 12,391	$ 11,868.1
Commercial mortgage loans
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	12,055.2	11,265.3	10,723.8
Commercial mortgage loans | A- and above
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	10,771.3	10,068.2
Commercial mortgage loans | BBB+ thru BBB-
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	1,110.4	1,011.9
Commercial mortgage loans | BB+ thru BB-
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	160.5	159.7
Commercial mortgage loans | B+ and below
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	13	25.5
Brick and mortar
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	11,795.2	10,921
Brick and mortar | A- and above
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	10,612.8	9,844.2
Brick and mortar | BBB+ thru BBB-
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	1,009.8	892.4
Brick and mortar | BB+ thru BB-
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	160.5	159.6
Brick and mortar | B+ and below
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	12.1	24.8
Credit tenant loans
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	260	344.3
Credit tenant loans | A- and above
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	158.5	224
Credit tenant loans | BBB+ thru BBB-
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	100.6	119.5
Credit tenant loans | BB+ thru BB-
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost		0.1
Credit tenant loans | B+ and below
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	0.9	0.7
Residential mortgage loans
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	1,219.9	1,125.7	$ 1,144.3
Residential mortgage loans | Performing
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	1,199.9	1,103.6
Residential mortgage loans | Non-performing
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	$ 20	$ 22.1
Mortgage loans, Days delinquent to be considered nonperforming	90 days	90 days
Home equity
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	$ 165.6	$ 218.8
Home equity | Performing
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	156.8	208
Home equity | Non-performing
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	8.8	10.8
First liens
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	1,054.3	906.9
First liens | Performing
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	1,043.1	895.6
First liens | Non-performing
Mortgage loan credit quality disclosures
Mortgage loans, Total amortized cost	$ 11.2	$ 11.3

Investments - Non-Accrual Mortg

Investments - Non-Accrual Mortgage Loans (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	$ 14.4	$ 18.7
Past due	65.8	39.6
Current	13,209.3	12,351.4
Mortgage loans, Total amortized cost	13,275.1	12,391	$ 11,868.1
Recorded investment 90 days or more past due and accruing	5.6	3.4
30 to 59 Days Past Due
Mortgage loan non-accrual and aging disclosures
Past due	42	22.5
60 to 89 Days Past Due
Mortgage loan non-accrual and aging disclosures
Past due	12.4	6.5
90 Days or More Past Due
Mortgage loan non-accrual and aging disclosures
Past due	11.4	10.6
Commercial mortgage loans
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Total amortized cost	12,055.2	11,265.3	10,723.8
Brick and mortar
Mortgage loan non-accrual and aging disclosures
Current	11,795.2	10,921
Mortgage loans, Total amortized cost	11,795.2	10,921
Credit tenant loans
Mortgage loan non-accrual and aging disclosures
Current	260	344.3
Mortgage loans, Total amortized cost	260	344.3
Residential mortgage loans
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Total amortized cost	1,219.9	1,125.7	$ 1,144.3
Home equity
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	8.8	10.8
Past due	4.4	3.6
Current	161.2	215.2
Mortgage loans, Total amortized cost	165.6	218.8
Home equity | 30 to 59 Days Past Due
Mortgage loan non-accrual and aging disclosures
Past due	1.9	2
Home equity | 60 to 89 Days Past Due
Mortgage loan non-accrual and aging disclosures
Past due	1.1	1
Home equity | 90 Days or More Past Due
Mortgage loan non-accrual and aging disclosures
Past due	1.4	0.6
First liens
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	5.6	7.9
Past due	61.4	36
Current	992.9	870.9
Mortgage loans, Total amortized cost	1,054.3	906.9
Recorded investment 90 days or more past due and accruing	5.6	3.4
First liens | 30 to 59 Days Past Due
Mortgage loan non-accrual and aging disclosures
Past due	40.1	20.5
First liens | 60 to 89 Days Past Due
Mortgage loan non-accrual and aging disclosures
Past due	11.3	5.5
First liens | 90 Days or More Past Due
Mortgage loan non-accrual and aging disclosures
Past due	$ 10	$ 10

Investments - Mortgage Loan Val

Investments - Mortgage Loan Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in mortgage loan valuation allowance
Beginning balance, Mortgage loan valuation allowance	$ 51.6	$ 56.5	$ 69.8
Provision: Mortgage loan valuation allowance	(4.2)	3.9	6.8
Charge-offs: Mortgage loan valuation allowance	(6.1)	(12.4)	(23.6)
Recoveries: Mortgage loan valuation allowance	3.6	3.7	3.6
Effect of exchange rates: Mortgage loan valuation allowance		(0.1)	(0.1)
Ending balance, Mortgage loan valuation allowance	44.9	51.6	56.5
Individually evaluated for impairment, Mortgage loan valuation allowance	5.9	7.5	11.4
Collectively evaluated for impairment, Mortgage loan valuation allowance	39	44.1	45.1
Individually evaluated for impairment, Mortgage loans	19.2	23.2	31.5
Collectively evaluated for impairment, Mortgage loans	13,255.9	12,367.8	11,836.6
Mortgage loans, Total amortized cost	$ 13,275.1	12,391	11,868.1
Commercial mortgage loans
Mortgage loan valuation allowance disclosures
Mortgage loans, Days delinquent to be analyzed for valuation allowance	60 days
Changes in mortgage loan valuation allowance
Beginning balance, Mortgage loan valuation allowance	$ 27.5	26.9	28.7
Provision: Mortgage loan valuation allowance	1.4	3.9	(0.9)
Charge-offs: Mortgage loan valuation allowance	(1.5)	(3.4)	(0.9)
Recoveries: Mortgage loan valuation allowance		0.1
Ending balance, Mortgage loan valuation allowance	27.4	27.5	26.9
Individually evaluated for impairment, Mortgage loan valuation allowance			2.4
Collectively evaluated for impairment, Mortgage loan valuation allowance	27.4	27.5	24.5
Individually evaluated for impairment, Mortgage loans			4.4
Collectively evaluated for impairment, Mortgage loans	12,055.2	11,265.3	10,719.4
Mortgage loans, Total amortized cost	12,055.2	11,265.3	10,723.8
Residential mortgage loans
Changes in mortgage loan valuation allowance
Beginning balance, Mortgage loan valuation allowance	24.1	29.6	41.1
Provision: Mortgage loan valuation allowance	(5.6)		7.7
Charge-offs: Mortgage loan valuation allowance	(4.6)	(9)	(22.7)
Recoveries: Mortgage loan valuation allowance	3.6	3.6	3.6
Effect of exchange rates: Mortgage loan valuation allowance		(0.1)	(0.1)
Ending balance, Mortgage loan valuation allowance	17.5	24.1	29.6
Individually evaluated for impairment, Mortgage loan valuation allowance	5.9	7.5	9
Collectively evaluated for impairment, Mortgage loan valuation allowance	11.6	16.6	20.6
Individually evaluated for impairment, Mortgage loans	19.2	23.2	27.1
Collectively evaluated for impairment, Mortgage loans	1,200.7	1,102.5	1,117.2
Mortgage loans, Total amortized cost	$ 1,219.9	$ 1,125.7	$ 1,144.3

Investments - Impaired Mortgage

Investments - Impaired Mortgage Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commercial mortgage loans
Impaired mortgage loans
Average investment in impaired mortgage loans		$ 4.8	$ 17.8
Interest income recognized on impaired mortgage loans		0.2	0.2
Brick and mortar
Impaired mortgage loans
Average investment in impaired mortgage loans with no related allowance		2.6	13.4
Average investment in impaired mortgage loans with related allowance		2.2	4.4
Interest income recognized on impaired mortgage loans with related allowance		0.2	0.2
Residential mortgage loans
Impaired mortgage loans
Recorded investment in impaired mortgage loans	$ 19.2	23.2
Unpaid principal balance of impaired mortgage loans	20.2	24.2
Related allowance for impaired mortgage loans	5.9	7.5
Average investment in impaired mortgage loans	21.3	25.2	30.1
Interest income recognized on impaired mortgage loans	0.4	0.6	0.8
Home equity
Impaired mortgage loans
Recorded investment in impaired mortgage loans with related allowance	13	13.7
Unpaid principal balance of impaired mortgage loans with related allowance	14.1	14.8
Related allowance for impaired mortgage loans	5.5	7
Average investment in impaired mortgage loans with related allowance	13.4	15.1	18
Interest income recognized on impaired mortgage loans with related allowance	0.3	0.4	0.6
First liens
Impaired mortgage loans
Recorded investment in impaired mortgage loans with no related allowance	1.5	3.6
Recorded investment in impaired mortgage loans with related allowance	4.7	5.9
Unpaid principal balance of impaired mortgage loans with no related allowance	1.5	3.6
Unpaid principal balance of impaired mortgage loans with related allowance	4.6	5.8
Related allowance for impaired mortgage loans	0.4	0.5
Average investment in impaired mortgage loans with no related allowance	2.6	3.5	4
Average investment in impaired mortgage loans with related allowance	5.3	6.6	8.1
Interest income recognized on impaired mortgage loans with related allowance	$ 0.1	$ 0.2	$ 0.2

Investments - Mortgage Loan Mod

Investments - Mortgage Loan Modifications (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)item
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	10	14	78
Recorded investment of mortgage loans modified as a troubled debt restructuring | $	$ 0.6	$ 0.6	$ 8.2
Number of mortgage loans modified as a troubled debt restructuring in payment default		2	4
Recorded investment of mortgage loans modified as a troubled debt restructuring in payment default | $			$ 0.7
Brick and mortar
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring			2
Recorded investment of mortgage loans modified as a troubled debt restructuring | $			$ 5.1
Number of mortgage loans modified as a troubled debt restructuring in payment default			1
Recorded investment of mortgage loans modified as a troubled debt restructuring in payment default | $			$ 0.7
Home equity
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	9	14	75
Recorded investment of mortgage loans modified as a troubled debt restructuring | $	$ 0.5	$ 0.6	$ 3
Number of mortgage loans modified as a troubled debt restructuring in payment default		2	3
First liens
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	1		1
Recorded investment of mortgage loans modified as a troubled debt restructuring | $	$ 0.1		$ 0.1

Investments - Real Estate and O

Investments - Real Estate and Other Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Real estate
Depreciation expense on invested real estate	$ 52	$ 49.3	$ 46.5
Accumulated depreciation on invested real estate	450.4	405.7
Summarized financial information of unconsolidated entities
Total assets, unconsolidated entities	123,621.2	101,099
Total liabilities, unconsolidated entities	73,688.8	52,839.3
Total equity, unconsolidated entities	49,932.4	48,259.7
Net investment in unconsolidated entities	1,223.8	1,098.3
Total revenues, unconsolidated entities	14,376.4	13,171	6,297
Net income, unconsolidated entities	3,455.3	4,866	1,152.7
Our share of net income of unconsolidated entities	232.7	165.3	$ 148.4
Other Types of Investments
Direct financing leases	$ 875.2	$ 819.3

Investments - Securities Posted

Investments - Securities Posted as Collateral (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Securities Posted as Collateral
Commercial mortgage loans and home equity mortgages posted as collateral associated with obligation under funding agreements with the Federal Home Loan Bank of Des Moines	$ 2,562.8	$ 2,705.5
Fixed maturity securities posted as collateral for a reinsurance arrangement, derivative credit support annex (collateral) agreements, Futures Commission Merchant agreements, a lending arrangement and an obligation under funding agreements with Federal Home Loan Bank of Des Moines	2,233.2	935.7
Securities posted as collateral eligible to be sold or repledged	$ 272.8	$ 295.2

Investments - Balance Sheet Off

Investments - Balance Sheet Offsetting, Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Financial Asset Offsetting
Gross amount of recognized assets subject to netting agreements	$ 928.3	$ 745.1
Amount of liabilities that offset the gross amount of assets subject to netting agreements not offset in statement of financial position	(294.2)	(409.7)
Collateral received, financial assets	(623.1)	(313.3)
Net amount of assets subject to netting agreements	11	22.1
Derivative assets
Financial Asset Offsetting
Gross amount of recognized assets subject to netting agreements	887.2	665.4
Amount of liabilities that offset the gross amount of assets subject to netting agreements not offset in statement of financial position	(294.2)	(409.7)
Collateral received, financial assets	(582)	(233.6)
Net amount of assets subject to netting agreements	11	22.1
Gross amount of assets not subject to netting agreements	6.4	1.2
Reverse repurchase agreements
Financial Asset Offsetting
Gross amount of recognized assets subject to netting agreements	41.1	79.7
Collateral received, financial assets	$ (41.1)	$ (79.7)

Investments - Balance Sheet O78

Investments - Balance Sheet Offsetting, Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Financial Liability Offsetting
Gross amount of recognized liabilities subject to netting agreements	$ 577.2
Amount of assets that offset the gross amount of liabilities subject to netting agreements not offset in statement of financial position	(294.2)
Collateral pledged, financial liabilities	(243.9)
Net amount of liabilities subject to netting agreements	39.1
Derivative liabilities
Financial Liability Offsetting
Gross amount of recognized liabilities subject to netting agreements	567.5	$ 758.6
Amount of assets that offset the gross amount of liabilities subject to netting agreements not offset in statement of financial position	(294.2)	(409.7)
Collateral pledged, financial liabilities	(243.9)	(253.9)
Net amount of liabilities subject to netting agreements	29.4	95
Gross amount of liabilities not subject to netting agreements	394.3	$ 421.5
Repurchase agreements
Financial Liability Offsetting
Gross amount of recognized liabilities subject to netting agreements	9.7
Net amount of liabilities subject to netting agreements	$ 9.7

Derivative Financial Instrume79

Derivative Financial Instruments - Notional Amounts and Credit Exposure (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Derivative Financial Instruments, exposure
Cash and securities posted under collateral arrangements associated with derivative credit support agreements and Futures Commission Merchant agreements	$ 322.4	$ 342.7
Aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a liability position	454.7	606.5
Collateral and initial margin posted supporting derivatives with credit-risk-related contingent features that were in a liability position	322.4	342.7
Additional collateral required to be posted if derivative credit-risk-related contingent features were triggered	42
Cash collateral received associated with derivative credit support annex agreements and Futures Commission Merchant agreements	576.3	217.5
Notional amount	46,370.8	45,028.4
Gross credit exposure	908.9	703.4
Less: collateral received	586.8	234.2
Net credit exposure	322.1	469.2
Interest rate swaps
Derivative Financial Instruments, exposure
Cash exchanged under contract	0
Principal payments made under contract	0
Notional amount	23,520.4	21,704.2
Gross credit exposure	733.1	505.5
Interest rate options
Derivative Financial Instruments, exposure
Notional amount	4,950.5	4,900
Gross credit exposure	27.3	34.1
Interest rate futures
Derivative Financial Instruments, exposure
Notional amount	96	162
Swaptions
Derivative Financial Instruments, exposure
Notional amount	77	259
Currency swaps
Derivative Financial Instruments, exposure
Notional amount	1,552	1,751
Gross credit exposure	106.2	105.6
Currency forwards
Derivative Financial Instruments, exposure
Notional amount	851.3	1,040.6
Gross credit exposure	6.4	4.4
Equity options
Derivative Financial Instruments, exposure
Notional amount	3,505.8	3,604.8
Gross credit exposure	28.2	39.9
Equity futures
Derivative Financial Instruments, exposure
Notional amount	545.1	514.2
Credit default swaps
Derivative Financial Instruments, exposure
Notional amount	961.3	1,084.5
Gross credit exposure	7	13.4
Total return swaps
Derivative Financial Instruments, exposure
Notional amount	90	90
Gross credit exposure	0.7	0.5
Credit Futures
Derivative Financial Instruments, exposure
Notional amount	11.9	13.1
Embedded derivative financial instruments
Derivative Financial Instruments, exposure
Notional amount	$ 10,209.5	$ 9,905

Derivative Financial Instrume80

Derivative Financial Instruments - Fair Value of Derivatives (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivatives, fair value disclosures
Derivative instruments, assets	$ 893.6	$ 666.6
Derivative instruments, liabilities	961.8	1,180.1
Fair value of embedded derivative liabilities reported with contractholder funds	176.5	177.4
Derivatives designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	91.2	103.5
Derivative instruments, liabilities	214.7	296.4
Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	802.4	563.1
Derivative instruments, liabilities	747.1	883.7
Interest rate contracts | Derivatives designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	4.4	9.4
Derivative instruments, liabilities	71.3	132.2
Interest rate contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	739.3	493
Derivative instruments, liabilities	200.6	255.8
Foreign exchange contracts | Derivatives designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	86.8	94.1
Derivative instruments, liabilities	143.4	164.2
Foreign exchange contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	27.2	16.4
Derivative instruments, liabilities	56.2	68.1
Equity contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	28.2	39.8
Derivative instruments, liabilities	95.9	112.3
Credit contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, assets	7.7	13.9
Derivative instruments, liabilities	5.7	39.7
Other contracts | Derivatives not designated as hedging instrument
Derivatives, fair value disclosures
Derivative instruments, liabilities	$ 388.7	$ 407.8

Derivative Financial Instrume81

Derivative Financial Instruments - Credit Derivatives Sold (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Credit default swaps
Credit derivatives sold disclosures
Notional amount	$ 784.8	$ 871.3
Fair value	2.1	(27.3)
Maximum future payments	$ 784.8	$ 871.3
Weighted average expected life	1 year 8 months 12 days	2 years 6 months
Single name credit default swaps
Credit derivatives sold disclosures
Notional amount	$ 669	$ 729
Fair value	4.1	(8.5)
Maximum future payments	$ 669	$ 729
Weighted average expected life	1 year 10 months 24 days	2 years 9 months 18 days
Single name credit default swaps | Corporate debt securities | AAA
Credit derivatives sold disclosures
Notional amount	$ 30	$ 30
Fair value	0.6	0.8
Maximum future payments	$ 30	$ 30
Weighted average expected life	2 years 2 months 12 days	3 years 2 months 12 days
Single name credit default swaps | Corporate debt securities | AA
Credit derivatives sold disclosures
Notional amount	$ 94	$ 74
Fair value	0.8	1.1
Maximum future payments	$ 94	$ 74
Weighted average expected life	1 year 2 months 12 days	2 years 3 months 18 days
Single name credit default swaps | Corporate debt securities | A
Credit derivatives sold disclosures
Notional amount	$ 145	$ 195
Fair value	1.2	2.2
Maximum future payments	$ 145	$ 195
Weighted average expected life	1 year 3 months 18 days	2 years 2 months 12 days
Single name credit default swaps | Corporate debt securities | BBB
Credit derivatives sold disclosures
Notional amount	$ 290	$ 310
Fair value	2.3	(0.9)
Maximum future payments	$ 290	$ 310
Weighted average expected life	2 years 1 month 6 days	2 years 10 months 24 days
Single name credit default swaps | Corporate debt securities | BB
Credit derivatives sold disclosures
Notional amount		$ 30
Fair value		(4.6)
Maximum future payments		$ 30
Weighted average expected life		3 years 1 month 6 days
Single name credit default swaps | Corporate debt securities | B
Credit derivatives sold disclosures
Notional amount	$ 20
Fair value	(1.8)
Maximum future payments	$ 20
Weighted average expected life	2 years 9 months 18 days
Single name credit default swaps | Corporate debt securities | CCC
Credit derivatives sold disclosures
Notional amount		$ 10
Fair value		(6.8)
Maximum future payments		$ 10
Weighted average expected life		4 years
Single name credit default swaps | Corporate debt securities | Near default
Credit derivatives sold disclosures
Notional amount	$ 10
Fair value	0.2
Maximum future payments	$ 10
Weighted average expected life	3 years
Single name credit default swaps | Government/municipalities | AA
Credit derivatives sold disclosures
Notional amount	$ 30	$ 30
Fair value	0.4	0.6
Maximum future payments	$ 30	$ 30
Weighted average expected life	2 years 3 months 18 days	3 years 3 months 18 days
Single name credit default swaps | Sovereign | AA
Credit derivatives sold disclosures
Notional amount	$ 10	$ 10
Fair value	0.1
Maximum future payments	$ 10	$ 10
Weighted average expected life	2 years 8 months 12 days	3 years 8 months 12 days
Single name credit default swaps | Sovereign | BBB
Credit derivatives sold disclosures
Notional amount	$ 40	$ 40
Fair value	0.3	(0.9)
Maximum future payments	$ 40	$ 40
Weighted average expected life	2 years 8 months 12 days	3 years 8 months 12 days
Basket and index credit default swaps
Credit derivatives sold disclosures
Notional amount	$ 115.8	$ 142.3
Fair value	(2)	(18.8)
Maximum future payments	$ 115.8	$ 142.3
Weighted average expected life	4 months 24 days	1 year 3 months 18 days
Basket and index credit default swaps | Corporate debt securities | Near default
Credit derivatives sold disclosures
Notional amount	$ 82.3	$ 100.4
Fair value	(1.6)	(17.7)
Maximum future payments	$ 82.3	$ 100.4
Weighted average expected life	2 months 12 days	1 year 2 months 12 days
Notional amount of derivative whose credit risk is borne by third party investors	$ 60	$ 78
Basket and index credit default swaps | Government/municipalities | AA
Credit derivatives sold disclosures
Notional amount	30	30
Fair value	(0.4)	(1.1)
Maximum future payments	$ 30	$ 30
Weighted average expected life	8 months 12 days	1 year 8 months 12 days
Basket and index credit default swaps | Structured finance | AAA
Credit derivatives sold disclosures
Notional amount		$ 11.9
Maximum future payments		$ 11.9
Weighted average expected life		7 months 6 days
Basket and index credit default swaps | Structured finance | AA
Credit derivatives sold disclosures
Notional amount	$ 3.5
Maximum future payments	$ 3.5
Weighted average expected life	9 months 18 days

Derivative Financial Instrume82

Derivative Financial Instruments - Fixed Maturities with Embedded Credit Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Derivative Financial Instruments
Future potential payments in the event of default of an investment in fixed maturity securities that contain embedded credit derivatives	$ 0
Hybrid instruments disclosures
Amortized cost	24.6	$ 87.3
Carrying value	$ 24.6	$ 87.3
Weighted average expected life	9 months 18 days	1 year 1 month 6 days
Corporate debt securities
Hybrid instruments disclosures
Amortized cost		$ 24.6
Carrying value		$ 24.6
Weighted average expected life		1 year
Corporate debt securities | A
Hybrid instruments disclosures
Amortized cost		$ 24.6
Carrying value		$ 24.6
Weighted average expected life		1 year
Structured finance
Hybrid instruments disclosures
Amortized cost	$ 24.6	$ 62.7
Carrying value	$ 24.6	$ 62.7
Weighted average expected life	9 months 18 days	1 year 2 months 12 days
Structured finance | AA
Hybrid instruments disclosures
Amortized cost	$ 14.1
Carrying value	$ 14.1
Weighted average expected life	7 months 6 days
Structured finance | A
Hybrid instruments disclosures
Amortized cost		$ 52.2
Carrying value		$ 52.2
Weighted average expected life		1 year 1 month 6 days
Structured finance | BBB
Hybrid instruments disclosures
Amortized cost	$ 3.5	$ 3.4
Carrying value	$ 3.5	$ 3.4
Weighted average expected life	9 months 18 days	1 year 7 months 6 days
Structured finance | BB
Hybrid instruments disclosures
Amortized cost	$ 2.3	$ 2.3
Carrying value	$ 2.3	$ 2.3
Weighted average expected life	9 months 18 days	1 year 7 months 6 days
Structured finance | CCC
Hybrid instruments disclosures
Amortized cost	$ 4.7	$ 4.8
Carrying value	$ 4.7	$ 4.8
Weighted average expected life	1 year 2 months 12 days	1 year 10 months 24 days

Derivative Financial Instrume83

Derivative Financial Instruments - Fair Value Hedges (Details) - Fair Value Hedges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	$ 18.6	$ 31	$ 33.1
Amount of gain (loss) recognized in net income on related hedged item	(18.2)	(30.6)	(35.2)
Fixed maturities, available-for-sale
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Gain (loss) on periodic settlements on interest rate and foreign exchange contracts in fair value hedge of fixed maturities, available-for-sale reported in net investment income	(41.9)	(72.8)	(93)
Investment contracts
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Gain (loss) on periodic settlements on interest rate and foreign exchange contracts in fair value hedge of investment contracts reported in benefits, claims and settlement expenses	2.6	3.7	4.3
Interest rate contracts | Fixed maturities, available-for-sale
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	19.5	26.4	25.4
Amount of gain (loss) recognized in net income on related hedged item	(19.2)	(26.1)	(27.7)
Interest rate contracts | Investment contracts
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	(0.9)	0.8	2
Amount of gain (loss) recognized in net income on related hedged item	$ 1	(0.7)	(1.9)
Foreign exchange contracts | Fixed maturities, available-for-sale
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives		3.8	5.5
Amount of gain (loss) recognized in net income on related hedged item		$ (3.8)	(5.4)
Foreign exchange contracts | Investment contracts
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives			0.2
Amount of gain (loss) recognized in net income on related hedged item			$ (0.2)

Derivative Financial Instrume84

Derivative Financial Instruments - Cash Flow Hedges (Details) - Cash Flow Hedges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Maximum length of time hedging exposure to variability in future cash flows for forecasted transactions	3 years 6 months
Gross unrealized gains (losses) reported in accumulated OCI related to active hedges of forecasted transactions	$ 16.2
Gross unrealized gains (losses) reclassified from accumulated OCI into net income due to forecasted transaction probable of not occurring	0	$ 0
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	(21.5)	57.1	$ 106.9
Amount of gain (loss) reclassified from accumulated OCI on derivatives (effective portion)	27.7	36.9	(3.8)
Net gains (losses) expected to be reclassified from accumulated OCI into net income in the next 12 months	3.7
Fixed maturities, available-for-sale
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Gain (loss) on periodic settlements on interest rate and foreign exchange contracts in cash flow hedge of fixed maturities, available-for-sale reported in net investment income	5.8	6.1	5.1
Investment contracts
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Gain (loss) on periodic settlements on interest rate and foreign exchange contracts in cash flow hedge of investment contracts reported in benefits, claims and settlement expenses	(15.7)	(18.3)	(11.1)
Interest rate contracts | Fixed maturities, available-for-sale | Net investment income
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	(33.1)	33.1	29
Amount of gain (loss) reclassified from accumulated OCI on derivatives (effective portion)	19.3	16.6	13.8
Interest rate contracts | Fixed maturities, available-for-sale | Net realized capital gains (losses)
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) reclassified from accumulated OCI on derivatives (effective portion)	11.2
Interest rate contracts | Investment contracts | Benefits, claims and settlement expenses
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	1.6	4.7	2
Interest rate contracts | Hedged debt | Operating expense
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) reclassified from accumulated OCI on derivatives (effective portion)	(9.2)	(8.2)	(7.4)
Foreign exchange contracts | Net realized capital gains (losses)
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Gain (loss) resulting from the ineffective portion in cash flow hedging relationships	0.3	0	0
Foreign exchange contracts | Fixed maturities, available-for-sale | Net realized capital gains (losses)
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	4	16.9	68.7
Amount of gain (loss) reclassified from accumulated OCI on derivatives (effective portion)	6.4	28.5	(10.2)
Foreign exchange contracts | Investment contracts | Benefits, claims and settlement expenses
Effect of derivatives in hedging relationships and the related hedged items on the consolidated statements of operations
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	$ 6	$ 2.4	$ 7.2

Derivative Financial Instrume85

Derivative Financial Instruments - Net Investment Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net investment hedges
Effect of derivatives on the consolidated financial statements
Amount of gain (loss) recognized in accumulated OCI on derivatives (effective portion)	$ 0	$ 1.7	$ 0

Derivative Financial Instrume86

Derivative Financial Instruments - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effect of derivatives not designated as hedging instruments on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	$ 172.5	$ (34.4)	$ (35.7)
Interest rate contracts
Effect of derivatives not designated as hedging instruments on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	243.3	73.8	246
Foreign exchange contracts
Effect of derivatives not designated as hedging instruments on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	20.1	(49.8)	(74.6)
Equity contracts
Effect of derivatives not designated as hedging instruments on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	(123.5)	(50.5)	21.9
Credit contracts
Effect of derivatives not designated as hedging instruments on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	37.4	3.5	(34.7)
Other contracts
Effect of derivatives not designated as hedging instruments on the consolidated statements of operations
Amount of gain (loss) recognized in net income on derivatives	$ (4.8)	$ (11.4)	$ (194.3)

Closed Block - Assets and Liabi

Closed Block - Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Closed Block liabilities and assets designated to the Closed Block
Closed Block liabilities: Policyholder dividend obligation related to earnings	$ 8.2
Closed Block liabilities: Policyholder dividend obligation related to net unrealized gains	117.9	$ 88.7
Closed Block liabilities
Closed Block liabilities: Future policy benefits and claims	4,068.4	4,229.2
Closed Block liabilities: Other policyholder funds	8.1	9.2
Closed Block liabilities: Policyholder dividends payable	232.5	246.4
Closed Block liabilities: Policyholder dividend obligation	126.1	88.7
Closed Block liabilities: Other liabilities	7.7	8.2
Total Closed Block liabilities	4,442.8	4,581.7
Assets designated to the Closed Block
Closed Block assets: Fixed maturities, available-for-sale	2,218.9	2,211.5
Closed Block assets: Fixed maturities, trading	6.7	10.3
Closed Block assets: Equity securities, available-for-sale	3	3.8
Closed Block assets: Mortgage loans	842.2	899.1
Closed Block assets: Policy loans	566.7	587.2
Closed Block assets: Other investments	62.4	81.9
Closed Block assets: Total investments	3,699.9	3,793.8
Closed Block assets: Cash and cash equivalents	76.2	88.8
Closed Block assets: Accrued investment income	43.6	45.3
Closed Block assets: Premiums due and other receivables	11.7	11.3
Closed Block assets: Deferred income tax asset	62.3	55.2
Closed Block assets: Other assets		0.2
Total assets designated to the Closed Block	3,893.7	3,994.6
Excess of Closed Block liabilities over assets designated to the Closed Block	549.1	587.1
Amounts included in accumulated other comprehensive income (loss)	0.7	9.3
Maximum future earnings to be recognized from Closed Block assets and liabilities	$ 549.8	$ 596.4	$ 648.9	$ 685.3

Closed Block - Revenues and Exp

Closed Block - Revenues and Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Closed Block: Premiums and other considerations	$ 298	$ 325.6	$ 351.9
Closed Block: Net investment income (loss)	181.6	187	201.9
Closed Block: Net realized capital gains (losses)	(1)	(0.2)	(2.3)
Closed Block: Total revenues	478.6	512.4	551.5
Expenses
Closed Block: Benefits, claims and settlement expenses	267.1	283.2	313.3
Closed Block: Dividends to policyholders	153.5	160.4	173.2
Closed Block: Operating expenses	3.6	3.9	4.3
Closed Block: Total expenses	424.2	447.5	490.8
Closed Block revenues, net of Closed Block expenses, before income taxes	54.4	64.9	60.7
Closed Block: Income taxes (benefits)	17.1	20.7	19.5
Closed Block revenues, net of Closed Block expenses and income taxes	37.3	44.2	41.2
Funding adjustment charges	9.3	8.3	(4.8)
Closed Block revenues, net of Closed Block expenses, income taxes and funding adjustment charges	$ 46.6	$ 52.5	$ 36.4

Closed Block - Change in Maximu

Closed Block - Change in Maximum Future Earnings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in maximum future earnings of the Closed Block
Maximum future earnings to be recognized from Closed Block assets and liabilities, Beginning of year	$ 596.4	$ 648.9	$ 685.3
Maximum future earnings to be recognized from Closed Block assets and liabilities, End of year	549.8	596.4	648.9
Closed Block revenues, net of Closed Block expenses, income taxes and funding adjustment charges	$ (46.6)	$ (52.5)	$ (36.4)

Deferred Acquisition Costs (Det

Deferred Acquisition Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in deferred acquisition costs
Balance at beginning of year, deferred acquisition costs	$ 3,276.1	$ 2,993	$ 3,077
Costs deferred during the year	402.3	390.3	404.1
Amortization of deferred acquisition costs	(285.1)	(270.8)	(367.2)
Adjustment related to unrealized (gains) losses on available-for-sale securities and derivative instruments	(13.1)	164.5	(120.9)
Other		(0.9)
Balance at end of year, deferred acquisition costs	$ 3,380.2	$ 3,276.1	$ 2,993

Insurance Liabilities - Compone

Insurance Liabilities - Components of Contractholder Funds (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Liabilities for investment contracts:
Liabilities for individual annuities	$ 10,864.9	$ 10,147.4
GICs	10,290.7	10,222.8
Funding agreements	8,270.3	6,863.4
Other investment contracts	1,840	2,007.4
Total liabilities for investment contracts	31,265.9	29,241
Universal life and other reserves	6,687.7	6,475.1
Contractholder funds	$ 37,953.6	$ 35,716.1

Insurance Liabilities - Contrac

Insurance Liabilities - Contractholder Funding Agreements (Details) $ in Millions, € in Billions	12 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2006EUR (€)	Dec. 31, 2006USD ($)	Mar. 31, 2004USD ($)	Dec. 31, 2001USD ($)	Dec. 31, 1998USD ($)
Funding agreement disclosures
Funding agreements	$ 8,270.3	$ 6,863.4
Principal Life Insurance Company
Funding agreement disclosures
Number of separate funding agreement programs | item	5
Number of funding agreement programs not guaranteed by PFG | item	3
Principal Life Insurance Company | 1998 Funding agreement program
Funding agreement disclosures
Maximum authorized amount of funding agreements to be issued									$ 4,000
Funding agreements	$ 106.7	107.5
Principal Life Insurance Company | 2001 Funding agreement program
Funding agreement disclosures
Maximum authorized amount of funding agreements to be issued								$ 7,000
Funding agreements	201.5	201.4
Principal Life Insurance Company | 2004 Funding agreement program
Funding agreement disclosures
Maximum authorized amount of funding agreements to be issued							$ 9,000
Funding agreements	119.8	246
Principal Life Insurance Company | 2006 Funding agreement program
Funding agreement disclosures
Maximum authorized amount of funding agreements to be issued					€ 4	$ 5,300
Funding agreements	702	1,021
Principal Life Insurance Company | 2011 Funding agreement program
Funding agreement disclosures
Maximum authorized amount of funding agreements to be issued				$ 5,000
Funding agreements	$ 4,389.4	$ 3,537
Additional maximum authorized amount of funding agreements to be issued			$ 4,000
Amount of funding agreement authorization used at time additional amount authorized			$ 5,000

Insurance Liabilities - Liabili

Insurance Liabilities - Liability for Unpaid Claims (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in unpaid claims
Balance at beginning of year, unpaid claims	$ 1,872.2	$ 1,771.4	$ 1,662.2
Balance at beginning of year, reinsurance recoverables for unpaid claims	314.1	284.6	254.9
Net balance at beginning of year, unpaid claims	1,558.1	1,486.8	1,407.3
Incurred:
Incurred: Current year	1,103.5	1,037	994.2
Incurred: Prior years	24.4	(18.1)	(17.8)
Total incurred	1,127.9	1,018.9	976.4
Payments:
Payments: Current year	701.9	646.7	614.2
Payments: Prior years	323.1	300.9	282.7
Total payments	1,025	947.6	896.9
Net balance at end of year, unpaid claims	1,661	1,558.1	1,486.8
Balance at end of year, reinsurance recoverables for unpaid claims	340.3	314.1	284.6
Balance at end of year, unpaid claims	2,001.3	1,872.2	1,771.4
Amount not included in the rollforward above:
Claim adjustment expense liabilities	$ 49.3	$ 58.9	$ 55.1

Insurance Liabilities - Claims

Insurance Liabilities - Claims Development Tables (Details) $ in Millions	Dec. 31, 2016USD ($)claim	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2010USD ($)	Dec. 31, 2009USD ($)	Dec. 31, 2008USD ($)	Dec. 31, 2007USD ($)
Claims Development [Line Items]
Total outstanding liabilities for unpaid claims net of reinsurance	$ 1,244.2
Long-Term Disability/Group Life Waiver
Claims Development [Line Items]
Net incurred claims	1,972.7
Net cumulative paid claims	1,026.4
Liability for unpaid claims net, not separately presented	203.7
Total outstanding liabilities for unpaid claims net of reinsurance	1,150
Long-Term Disability/Group Life Waiver | 2007
Claims Development [Line Items]
Net incurred claims	196.8	$ 198	$ 200.5	$ 203.4	$ 206.6	$ 211.4	$ 220.7	$ 216.3	$ 218	$ 228.1
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	8,721
Net cumulative paid claims	$ 151	145.1	139.1	131.5	123.7	113.1	101.5	85.9	57.3	$ 14.2
Long-Term Disability/Group Life Waiver | 2008
Claims Development [Line Items]
Net incurred claims	199.8	201.6	205.5	209.5	218.5	225.9	226.3	222.3	227.7
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	7,728
Net cumulative paid claims	$ 146.4	139.4	131.7	123.2	113.3	99.4	84	58.1	$ 15.1
Long-Term Disability/Group Life Waiver | 2009
Claims Development [Line Items]
Net incurred claims	205.8	208.5	214.1	217.7	224.8	224.2	224.4	218.6
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	6,553
Net cumulative paid claims	$ 141.8	133.1	124.6	113.8	101	82.6	55.2	$ 13.4
Long-Term Disability/Group Life Waiver | 2010
Claims Development [Line Items]
Net incurred claims	154.1	155.7	162.7	172	176.2	176.7	184.1
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	5,644
Net cumulative paid claims	$ 100.9	94.2	85.9	78.4	67.1	46.5	$ 10.4
Long-Term Disability/Group Life Waiver | 2011
Claims Development [Line Items]
Net incurred claims	172.3	178.4	184.8	185.4	192.6	203.7
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	6,282
Net cumulative paid claims	$ 105.2	95.4	85.7	72.5	50	$ 11.2
Long-Term Disability/Group Life Waiver | 2012
Claims Development [Line Items]
Net incurred claims	181.8	189.5	191.1	200	217.9
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	6,441
Net cumulative paid claims	$ 104.6	93.7	80.8	55.1	$ 13.8
Long-Term Disability/Group Life Waiver | 2013
Claims Development [Line Items]
Net incurred claims	190.7	188.4	203.3	219.3
Incurred but not reported claims	$ 1.6
Cumulative number of reported claims | claim	7,041
Net cumulative paid claims	$ 97	81.4	55	$ 12.5
Long-Term Disability/Group Life Waiver | 2014
Claims Development [Line Items]
Net incurred claims	214.4	231.4	242.2
Incurred but not reported claims	$ 3.8
Cumulative number of reported claims | claim	7,560
Net cumulative paid claims	$ 96.3	66	$ 16.1
Long-Term Disability/Group Life Waiver | 2015
Claims Development [Line Items]
Net incurred claims	227.2	231
Incurred but not reported claims	$ 6.3
Cumulative number of reported claims | claim	7,075
Net cumulative paid claims	$ 67	16.9
Long-Term Disability/Group Life Waiver | 2016
Claims Development [Line Items]
Net incurred claims	229.8
Incurred but not reported claims	$ 83
Cumulative number of reported claims | claim	3,936
Net cumulative paid claims	$ 16.2
Dental/Vision/Short-Term Disability
Claims Development [Line Items]
Net incurred claims	1,045.8
Net cumulative paid claims	997
Total outstanding liabilities for unpaid claims net of reinsurance	48.8
Dental/Vision/Short-Term Disability | 2015
Claims Development [Line Items]
Net incurred claims	501.6	508.7
Incurred but not reported claims	$ 0.1
Cumulative number of reported claims | claim	2,390,598
Net cumulative paid claims	$ 501.6	461
Dental/Vision/Short-Term Disability | 2016
Claims Development [Line Items]
Net incurred claims	544.2
Incurred but not reported claims	$ 29.5
Cumulative number of reported claims | claim	2,429,004
Net cumulative paid claims	$ 495.4
Group Life
Claims Development [Line Items]
Net incurred claims	417.6
Net cumulative paid claims	372.8
Liability for unpaid claims net, not separately presented	0.6
Total outstanding liabilities for unpaid claims net of reinsurance	45.4
Group Life | 2015
Claims Development [Line Items]
Net incurred claims	195	194.4
Incurred but not reported claims	$ 0.4
Cumulative number of reported claims | claim	4,718
Net cumulative paid claims	$ 193.8	$ 159.3
Group Life | 2016
Claims Development [Line Items]
Net incurred claims	222.6
Incurred but not reported claims	$ 21
Cumulative number of reported claims | claim	4,634
Net cumulative paid claims	$ 179

Insurance Liabilities - Reconci

Insurance Liabilities - Reconciliation of Unpaid Claims to Liability for Unpaid Claims Table (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net outstanding liabilities for unpaid claims	$ 1,244.2
Reconciling items
Reinsurance recoverable on unpaid claims	77.3
Impact of discounting	(234.1)
Liability for unpaid claims - short duration contracts	1,087.4
Insurance lines other than short duration	913.9
Liability for unpaid claims	2,001.3	$ 1,872.2	$ 1,771.4	$ 1,662.2
Long-Term Disability/Group Life Waiver
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net outstanding liabilities for unpaid claims	1,150
Reconciling items
Reinsurance recoverable on unpaid claims	76.8
Impact of discounting	(234.1)	(246.1)
Liability for unpaid claims - short duration contracts	992.7	984.4
Dental/Vision/Short-Term Disability
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net outstanding liabilities for unpaid claims	48.8
Reconciling items
Liability for unpaid claims - short duration contracts	48.8	47.8
Group Life
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net outstanding liabilities for unpaid claims	45.4
Reconciling items
Reinsurance recoverable on unpaid claims	0.5
Liability for unpaid claims - short duration contracts	$ 45.9	$ 36.4

Insurance Liabilities - Claim D

Insurance Liabilities - Claim Duration and Payout Table (Details)	Dec. 31, 2016
Long-Term Disability/Group Life Waiver
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	7.10%
Year 2	22.20%
Year 3	13.70%
Year 4	7.90%
Year 5	6.00%
Year 6	5.30%
Year 7	4.20%
Year 8	4.00%
Year 9	3.30%
Year 10	3.00%
Dental/Vision/Short-Term Disability
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	91.80%
Year 2	8.00%
Group Life
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	81.70%
Year 2	17.40%

Insurance Liabilities - Discoun

Insurance Liabilities - Discounting Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	$ 1,087.4
Aggregate amount of discount	234.1
Long-Term Disability/Group Life Waiver
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	992.7	$ 984.4
Aggregate amount of discount	234.1	246.1
Interest accretion	$ 36.3	$ 37.6	$ 38.1
Long-Term Disability/Group Life Waiver | Minimum
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Discount rate	3.30%	3.30%
Long-Term Disability/Group Life Waiver | Maximum
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Discount rate	7.00%	7.00%
Dental/Vision/Short-Term Disability
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	$ 48.8	$ 47.8
Group Life
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	$ 45.9	$ 36.4

Debt - Short-Term Debt (Details

Debt - Short-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Short-Term Debt
Short-term debt	$ 51.4	$ 181.1
Credit facilities	1,005	1,005
Outstanding borrowings related to credit facilities	51.4	181.1
Assets pledged as support for credit facilities	$ 0	$ 0
Weighted-average interest rates on short-term borrowings (as a percent)	4.40%	4.20%
Principal Life Insurance Company
Short-Term Debt
Credit facilities	$ 45
Principal International Chile
Short-Term Debt
Credit facilities	60
Line of credit
Short-Term Debt
Short-term debt	51.4	$ 157.2
Line of credit | Principal Financial Services, Inc., Principal Life Insurance Company, and Principal Financial Group, co-borrowers
Short-Term Debt
Credit facilities	$ 400
Term of credit facility	5 years
Line of credit | Principal Life Insurance Company
Short-Term Debt
Credit facilities	$ 300
Term of credit facility	364 days
Line of credit | Principal Financial Services, Inc., Principal Life Insurance Company, Principal Financial Services V (UK) LTD, and Principal Financial Group, co-borrowers
Short-Term Debt
Credit facilities	$ 200
Term of credit facility	5 years
Other recourse short-term debt
Short-Term Debt
Short-term debt		$ 23.9
Commercial paper
Short-Term Debt
Support provided by back-stop facility for commercial paper program (as a percent)	100.00%	100.00%
Back-stop facility outstanding balances	$ 0	$ 0

Debt - Components of Long-Term

Debt - Components of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Long-Term Debt
Long-term debt principal	$ 3,155.6	$ 3,292.8
Net unamortized discount, premium and debt issuance costs	(29.9)	(27.6)
Long-term debt carrying amount	$ 3,125.7	$ 3,265.2
1.85% notes payable, due 2017
Long-Term Debt
Long-term debt interest rate (as a percent)		1.85%
Long-term debt principal		$ 300
Net unamortized discount, premium and debt issuance costs		(0.9)
Long-term debt carrying amount		$ 299.1
8.875% notes payable, due 2019
Long-Term Debt
Long-term debt interest rate (as a percent)		8.875%
Long-term debt principal		$ 350
Net unamortized discount, premium and debt issuance costs		(1.2)
Long-term debt carrying amount		$ 348.8
3.3% notes payable, due 2022
Long-Term Debt
Long-term debt interest rate (as a percent)	3.30%	3.30%
Long-term debt principal	$ 300	$ 300
Net unamortized discount, premium and debt issuance costs	(2.2)	(2.5)
Long-term debt carrying amount	$ 297.8	$ 297.5
3.125% notes payable, due 2023
Long-Term Debt
Long-term debt interest rate (as a percent)	3.125%	3.125%
Long-term debt principal	$ 300	$ 300
Net unamortized discount, premium and debt issuance costs	(1.8)	(2)
Long-term debt carrying amount	$ 298.2	$ 298
3.4% notes payable, due 2025
Long-Term Debt
Long-term debt interest rate (as a percent)	3.40%	3.40%
Long-term debt principal	$ 400	$ 400
Net unamortized discount, premium and debt issuance costs	(3.9)	(4.3)
Long-term debt carrying amount	$ 396.1	$ 395.7
3.1% notes payable, due 2026
Long-Term Debt
Long-term debt interest rate (as a percent)	3.10%
Long-term debt principal	$ 350
Net unamortized discount, premium and debt issuance costs	(3.3)
Long-term debt carrying amount	$ 346.7
6.05% notes payable, due 2036
Long-Term Debt
Long-term debt interest rate (as a percent)	6.05%	6.05%
Long-term debt principal	$ 505.6	$ 600
Net unamortized discount, premium and debt issuance costs	(2.7)	(3.3)
Long-term debt carrying amount	$ 502.9	$ 596.7
4.625% notes payable, due 2042
Long-Term Debt
Long-term debt interest rate (as a percent)	4.625%	4.625%
Long-term debt principal	$ 300	$ 300
Net unamortized discount, premium and debt issuance costs	(3.4)	(3.5)
Long-term debt carrying amount	$ 296.6	$ 296.5
4.35% notes payable, due 2043
Long-Term Debt
Long-term debt interest rate (as a percent)	4.35%	4.35%
Long-term debt principal	$ 300	$ 300
Net unamortized discount, premium and debt issuance costs	(3.4)	(3.5)
Long-term debt carrying amount	$ 296.6	$ 296.5
4.3% notes payable, due 2046
Long-Term Debt
Long-term debt interest rate (as a percent)	4.30%
Long-term debt principal	$ 300
Net unamortized discount, premium and debt issuance costs	(3.5)
Long-term debt carrying amount	$ 296.5
4.7% notes payable, due 2055
Long-Term Debt
Long-term debt interest rate (as a percent)	4.70%	4.70%
Long-term debt principal	$ 400	$ 400
Net unamortized discount, premium and debt issuance costs	(5)	(5)
Long-term debt carrying amount	395	395
Non-recourse mortgages and notes payable
Long-Term Debt
Long-term debt principal	0	42.8
Net unamortized discount, premium and debt issuance costs	(0.7)	(1.4)
Long-term debt carrying amount	$ (0.7)	$ 41.4

Debt - Senior notes (Details)

Debt - Senior notes (Details) - USD ($) $ in Millions

May 07, 2015

Sep. 05, 2012

Aug. 15, 2009

Dec. 31, 2016

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Nov. 10, 2016

Nov. 16, 2012

May 18, 2009

Dec. 05, 2006

Oct. 16, 2006

Long-Term Debt

Principal repayments of long-term debt

$ 799.3

$ 52.6

$ 100.3

Maximum | Junior subordinated notes

Long-Term Debt

Years interest payments on debt can be deferred

5 years

3.1% notes payable, due 2026 and 4.3% notes payable, due 2046 | Senior notes

Long-Term Debt

Long-term debt issued

$ 650

3.1% notes payable, due 2026

Long-Term Debt

Long-term debt interest rate (as a percent)

3.10%

3.10%

3.1% notes payable, due 2026 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

3.10%

Long-term debt issued

$ 350

4.3% notes payable, due 2046

Long-Term Debt

Long-term debt interest rate (as a percent)

4.30%

4.30%

4.3% notes payable, due 2046 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

4.30%

Long-term debt issued

$ 300

3.4% notes payable, due 2025

Long-Term Debt

Long-term debt interest rate (as a percent)

3.40%

3.40%

3.40%

3.4% notes payable, due 2025 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

3.40%

Long-term debt issued

$ 400

4.7% notes payable, due 2055

Long-Term Debt

Long-term debt interest rate (as a percent)

4.70%

4.70%

4.70%

4.7% notes payable, due 2055 | Junior subordinated notes

Long-Term Debt

Long-term debt interest rate (as a percent)

4.70%

Long-term debt issued

$ 400

Reference rate for floating rate of debt instrument

3-month LIBOR

Spread added to floating reference interest rate (as a percent)

3.044%

1.85% notes payable, due 2017; 3.125% notes payable, due 2023; and 4.35% notes payable, due 2043 | Senior notes

Long-Term Debt

Long-term debt issued

$ 900

1.85% notes payable, due 2017

Long-Term Debt

Long-term debt interest rate (as a percent)

1.85%

1.85% notes payable, due 2017 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

1.85%

Long-term debt issued

$ 300

3.125% notes payable, due 2023

Long-Term Debt

Long-term debt interest rate (as a percent)

3.125%

3.125%

3.125%

3.125% notes payable, due 2023 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

3.125%

Long-term debt issued

$ 300

4.35% notes payable, due 2043

Long-Term Debt

Long-term debt interest rate (as a percent)

4.35%

4.35%

4.35%

4.35% notes payable, due 2043 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

4.35%

Long-term debt issued

$ 300

3.3% notes payable, due 2022 and 4.625% notes payable, due 2042 | Senior notes

Long-Term Debt

Long-term debt issued

$ 600

3.3% notes payable, due 2022

Long-Term Debt

Long-term debt interest rate (as a percent)

3.30%

3.30%

3.30%

3.3% notes payable, due 2022 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

3.30%

Long-term debt issued

$ 300

4.625% notes payable, due 2042

Long-Term Debt

Long-term debt interest rate (as a percent)

4.625%

4.625%

4.625%

4.625% notes payable, due 2042 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

4.625%

Long-term debt issued

$ 300

7.875% notes payable, due 2014 and 8.875% notes payable, due 2019 | Senior notes

Long-Term Debt

Long-term debt issued

$ 750

7.875% notes payable, due 2014 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

7.875%

Long-term debt issued

$ 400

Principal repayments of long-term debt

$ 400

8.875% notes payable, due 2019

Long-Term Debt

Long-term debt interest rate (as a percent)

8.875%

8.875% notes payable, due 2019 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

8.875%

Long-term debt issued

$ 350

8.2% notes payable, due 2009 | Senior notes

Long-Term Debt

Principal repayments of long-term debt

$ 440.9

6.05% notes payable, due 2036

Long-Term Debt

Long-term debt interest rate (as a percent)

6.05%

6.05%

6.05%

6.05% notes payable, due 2036 | Senior notes

Long-Term Debt

Long-term debt interest rate (as a percent)

6.05%

6.05%

Long-term debt issued

$ 100

$ 500

Principal repayments of long-term debt

$ 94.4

Debt - Non-Recourse Mortgages a

Debt - Non-Recourse Mortgages and Notes Payable (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Long-Term Debt
Outstanding principal balances	$ 3,155.6	$ 3,292.8
Non-recourse mortgages and notes payable
Long-Term Debt
Outstanding principal balances	$ 0	42.8
Outstanding principal balances per real estate development, low end of range		1.8
Outstanding principal balances per real estate development, high end of range		41.1
Real estate		$ 79.5

Debt - Future Maturities of Lon

Debt - Future Maturities of Long-Term (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Future maturities of long-term debt
Year 6 and thereafter: Long-term debt maturities	$ 3,125.7
Long-term debt carrying amount	$ 3,125.7	$ 3,265.2

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes
Current income taxes (benefits): U.S. federal	$ 38.6	$ 225.9	$ 242.1
Current income taxes (benefits): State	(1.9)	12.3	4.7
Current income taxes (benefits): Foreign	36.6	32.6	67.6
Current income taxes (benefits): Tax benefit of operating loss carryforwards	(17.5)	(52)	(163)
Total current income taxes (benefits)	55.8	218.8	151.4
Deferred income taxes (benefits): U.S. federal	171.7	79.1	148
Deferred income taxes (benefits): State	(20.6)	(1)	(32.8)
Deferred income taxes (benefits): Foreign	23	(119.3)	51.9
Deferred income taxes (benefits)	174.1	(41.2)	167.1
Income taxes (benefits)	$ 229.9	$ 177.6	$ 318.5

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate and Income Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation between the U.S. corporate income tax rate and the effective income tax rate from continuing operations
U.S. corporate statutory income tax rate (as a percent)	35.00%	35.00%	35.00%
Dividends received deduction (as a percent)	(10.00%)	(11.00%)	(10.00%)
Impact of equity method presentation (as a percent)	(3.00%)	(3.00%)	(2.00%)
Tax credits (as a percent)	(2.00%)	(2.00%)	(2.00%)
Interest exclusion from taxable income (as a percent)	(1.00%)	(1.00%)	(1.00%)
Foreign country permanent tax adjustments	(1.00%)
Impact of noncontrolling interest presentation	(1.00%)
Merger of Chilean legal entities (as a percent)		(7.00%)
Foreign tax rate differential (as a percent)			(2.00%)
Impact of court ruling on some uncertain tax positions (as a percent)		3.00%
Impact of enactment of tax legislation (as a percent)			4.00%
Other income tax rate impacts (as a percent)	(3.00%)	(2.00%)	(1.00%)
Effective income tax rate (as a percent)	14.00%	12.00%	21.00%
Income (loss) before income taxes
Income (loss) before income taxes - domestic	$ 1,261.4	$ 1,195.3	$ 1,203.7
Income (loss) before income taxes - foreign	330.3	235.5	291.2
Income (loss) before income taxes	$ 1,591.7	$ 1,430.8	$ 1,494.9

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits and Deferred Income Taxes (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended			12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
Net deferred income tax assets						$ 103.9	$ 96
Net deferred income tax liabilities						(972.4)	(697.2)
Total net deferred income tax liabilities						(868.5)	(601.2)
Changes in Unrecognized Tax Benefits
Beginning balance, Unrecognized tax benefits			$ 172.4			219	172.4
Additions based on tax positions related to the current year						0.8	12.9
Additions for tax positions of prior years						0.8	45.9
Reductions for tax positions related to the current year						(12.6)	(8.7)
Reductions for tax positions of prior years						(0.2)	(3.5)
Ending balance, Unrecognized tax benefits						207.8	219
Amount of unrecognized tax benefits that would reduce the effective income tax rate, if recognized						81
Accumulated pre-tax interest and penalties related to unrecognized tax benefits						142.4	137.9
Deferred income tax assets:
Insurance liabilities						100.8	85.8
Investments, including derivative liabilities						352.7	368.8
Net operating and capital loss carryforwards						78.7	80.9
Tax credit carryforwards						275.7	227.4
Employee benefits						500.8	534.8
Foreign currency translation						105	123.4
Other deferred income tax assets						49.1	64.3
Gross deferred income tax assets						1,462.8	1,485.4
Valuation allowance						(7.3)	(11.9)
Total deferred income tax assets						1,455.5	1,473.5
Deferred income tax liabilities:
Deferred acquisition costs						(899.7)	(866.1)
Investments, including derivative assets						(460.4)	(379.6)
Net unrealized gains on available-for-sale securities						(536.7)	(431.2)
Deferred income tax liabilities: Real estate						(117.5)	(123.1)
Intangible assets						(256)	(235.4)
Other deferred income tax liabilities						(53.7)	(39.3)
Total deferred income tax liabilities						(2,324)	(2,074.7)
Total net deferred income tax liabilities						(868.5)	(601.2)
Deferred income tax disclosures
Accumulated but undistributed earnings from operations of foreign subsidiaries for which U.S. federal and state deferred income taxes have not been provided						1,088.4	1,004.6
Excess book carrying value over tax basis with respect to the original investment of foreign subsidiaries for which U.S. federal and state deferred income taxes have not been provided						106.2
Current income tax receivables associated with outstanding audit issues
Current income tax (receivables) payables associated with outstanding audit issues						(242.9)	(229.9)
Tax return examinations and court rulings
Impact of court ruling on uncertain tax positions			$ (30.3)		$ (47.5)
Brazil
Deferred income tax disclosures
Transition period for tax increases per enacted tax legislation	3 years
Chile
Deferred income tax disclosures
Transition period for tax increases per enacted tax legislation		5 years
Increase in net deferred tax liabilities resulting from enactment of tax legislation				$ 58.1
U.S. Federal
Income Taxes
Net deferred income tax liabilities						(733.3)	(459.5)
Deferred income tax assets:
Tax credit carryforwards						275.7	227.4
State
Income Taxes
Net deferred income tax assets						67.8	53.3
Deferred income tax disclosures-operating loss carryforwards
Net operating and capital loss carryforwards						587.7	387.7
Foreign
Income Taxes
Net deferred income tax assets						36.1	42.7
Net deferred income tax liabilities						(239.1)	(237.7)
Deferred income tax disclosures-operating loss carryforwards
Net operating loss carryforwards						151.6	197.1
Valuation allowances on income tax benefits primarily associated with foreign net operating loss carryforwards						$ 7.3	$ 11.9

Employee and Agent Benefits - B

Employee and Agent Benefits - Benefit Obligation, Funded Status, and Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 31, 2016
Pension benefits
Defined Benefit Plan Disclosures
Eligibility age		21 years
Period of employment used to calculate average annual compensation for the final average pay benefit		5 years
Maximum age used to calculate a partial benefit accrual of final average pay benefits		65 years
Minimum years of potential service used to calculate a partial benefit accrual of final average pay benefits		35 years
Change in benefit obligation
Benefit obligation at beginning of year		$ (3,052.2)	$ (3,060)
Service cost		65	63.2	$ 54
Interest cost		134.9	120.3	117.1
Actuarial gain (loss)		(39.3)	96.3
Benefits paid		235.2	95
Benefit obligation at end of year	$ (3,052.2)	(3,056.2)	(3,052.2)	(3,060)
Change in plan assets
Fair value of plan assets at beginning of year		2,166.3	2,218.3
Actual return on plan assets		181.6	(50)
Employer contribution		78.1	93
Benefits paid		235.2	95
Fair value of plan assets at end of year	2,166.3	2,190.8	2,166.3	2,218.3
Amount recognized in statement of financial position
Amount recognized in other liabilities	(885.9)	(865.4)	(885.9)
Total assets (liabilities) recognized in statement of financial position	(885.9)	(865.4)	(885.9)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	771.2	706.9	771.2
Prior service (benefit) cost	(5.1)	(2.9)	(5.1)
Pre-tax accumulated other comprehensive (income) loss	766.1	704	766.1
Additional defined benefit plan disclosures
Accumulated benefit obligation	2,799.2	2,821.1	2,799.2
Information for Defined Benefit Plans With an Accumulated Benefit Obligation in Excess of Plan Assets
Projected benefit obligation for defined benefit plans with an accumulated benefit obligation in excess of plan assets	3,052.2	3,056.2	3,052.2
Accumulated benefit obligation for defined benefit plans with an accumulated benefit obligation in excess of plan assets	2,799.2	2,821.1	2,799.2
Fair value of plan assets for defined benefit plans with an accumulated benefit obligation in excess of plan assets	2,166.3	2,190.8	2,166.3
Components of Net Periodic Benefit Cost (Income)
Service cost		65	63.2	54
Interest cost		134.9	120.3	117.1
Expected return on plan assets		(155)	(160.6)	(131.9)
Amortization of prior service (benefit) cost		(2.2)	(1.9)	(4.7)
Recognized net actuarial (gain) loss		77	102.4	50.5
Net periodic benefit cost (income)		119.7	123.4	85
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss		12.7	114.3
Amortization of net gain (loss)		(77)	(102.4)
Amortization of prior service benefit (cost)		2.2	1.9
Total recognized in pre-tax accumulated other comprehensive (income) loss		(62.1)	13.8
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss		57.6	137.2
Estimated amounts that will be amortized from accumulated other comprehensive income into net periodic benefit cost during the next fiscal year
Estimated net actuarial (gain) loss that will be amortized from accumulated other comprehensive income into net periodic benefit cost during the next fiscal year		68
Estimated prior service cost (benefit) that will be amortized from accumulated other comprehensive income into net periodic benefit cost during the next fiscal year		(2.3)
Qualified defined benefit pension plans
Change in benefit obligation
Service cost		58.1	54.8
Interest cost		115.9	102.3
Change in plan assets
Fair value of plan assets at beginning of year		2,166.3
Fair value of plan assets at end of year	2,166.3	2,190.8	2,166.3
Amount recognized in statement of financial position
Amount recognized in other liabilities	(453)	(410)	(453)
Total assets (liabilities) recognized in statement of financial position	(453)	(410)	(453)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	659	587.5	659
Prior service (benefit) cost	(2.6)	(1.6)	(2.6)
Pre-tax accumulated other comprehensive (income) loss	656.4	585.9	656.4
Components of Net Periodic Benefit Cost (Income)
Service cost		58.1	54.8
Interest cost		115.9	102.3
Expected return on plan assets		(155)	(160.6)
Amortization of prior service (benefit) cost		(1.1)	(0.8)
Recognized net actuarial (gain) loss		69.5	86.3
Net periodic benefit cost (income)		$ 87.4	82
Plan actuarial gain and loss amortization disclosures
Allowable corridor not used for amortization of actuarial gains and losses of qualified pension plan (as a percent)		10.00%
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss		$ (2)	142.1
Amortization of net gain (loss)		(69.5)	(86.3)
Amortization of prior service benefit (cost)		1.1	0.8
Total recognized in pre-tax accumulated other comprehensive (income) loss		(70.4)	56.6
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss		17	138.6
Nonqualified defined benefit pension plans
Change in benefit obligation
Service cost		6.9	8.4
Interest cost		19	18
Amount recognized in statement of financial position
Amount recognized in other liabilities	(432.9)	(455.4)	(432.9)
Total assets (liabilities) recognized in statement of financial position	(432.9)	(455.4)	(432.9)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	112.2	119.4	112.2
Prior service (benefit) cost	(2.5)	(1.3)	(2.5)
Pre-tax accumulated other comprehensive (income) loss	109.7	118.1	109.7
Additional defined benefit plan disclosures
Market value of assets held in Rabbi trusts for benefit of nonqualified pension plan participants	330.8	341	330.8
Components of Net Periodic Benefit Cost (Income)
Service cost		6.9	8.4
Interest cost		19	18
Amortization of prior service (benefit) cost		(1.1)	(1.1)
Recognized net actuarial (gain) loss		7.5	16.1
Net periodic benefit cost (income)		32.3	41.4
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss		14.7	(27.8)
Amortization of net gain (loss)		(7.5)	(16.1)
Amortization of prior service benefit (cost)		1.1	1.1
Total recognized in pre-tax accumulated other comprehensive (income) loss		8.3	(42.8)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss		$ 40.6	(1.4)
Other postretirement benefits
Defined Benefit Plan Disclosures
Eligibility age		57 years
Eligibility service period		10 years
Change in benefit obligation
Benefit obligation at beginning of year		$ (165.7)	(169.7)
Service cost		2.1	2	1.4
Interest cost		6.2	6.6	6.6
Actuarial gain (loss)		5.8	(2.7)
Participant contributions		(3.9)	(6.4)
Benefits paid		10.7	12.7
Plan amendments		51.6	9.7
Other changes in benefit obligation			(0.7)
Benefit obligation at end of year	(165.7)	(109.8)	(165.7)	(169.7)
Change in plan assets
Fair value of plan assets at beginning of year		627	639.7
Actual return on plan assets		8	(6.9)
Employer contribution		0.4	0.5
Participant contributions		(3.9)	(6.4)
Benefits paid		10.7	12.7
Fair value of plan assets at end of year	627	628.6	627	639.7
Amount recognized in statement of financial position
Amount recognized in other assets	461.9	520.8	461.9
Amount recognized in other liabilities	(0.6)	(2)	(0.6)
Total assets (liabilities) recognized in statement of financial position	461.3	518.8	461.3
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	(8.6)	10	(8.6)
Prior service (benefit) cost	(33)	(58.7)	(33)
Pre-tax accumulated other comprehensive (income) loss	(41.6)	(48.7)	(41.6)
Additional defined benefit plan disclosures
Medicare subsidies received, accrued and included in service cost		0.1	0.7	0.7
Reduction of accumulated postretirement benefit obligation due to elimination of subsidies for pre-65 employees and agents					$ 51.6
Reduction of accumulated postretirement benefit obligation due to change in post-65 medical plan			15.5
Adjustment to accumulated post-retirement benefit obligation related to dental plan benefits	5.8
Information for Defined Benefit Plans With an Accumulated Benefit Obligation in Excess of Plan Assets
Accumulated benefit obligation for defined benefit plans with an accumulated benefit obligation in excess of plan assets	1.3	2.6	1.3
Fair value of plan assets for defined benefit plans with an accumulated benefit obligation in excess of plan assets	$ 0.7	0.6	0.7
Components of Net Periodic Benefit Cost (Income)
Service cost		2.1	2	1.4
Interest cost		6.2	6.6	6.6
Expected return on plan assets		(32.6)	(33.9)	(32.6)
Amortization of prior service (benefit) cost		(25.9)	(18.5)	(20.3)
Recognized net actuarial (gain) loss		0.2	(0.8)	(3.4)
Plan amendments			5.8
Net periodic benefit cost (income)		(50)	(38.8)	$ (48.3)
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss		18.8	43.5
Amortization of net gain (loss)		(0.2)	0.8
Amortization of prior service benefit (cost)		25.9	18.5
Plan amendments		(51.6)	(15.5)
Total recognized in pre-tax accumulated other comprehensive (income) loss		(7.1)	47.3
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss		(57.1)	$ 8.5
Estimated amounts that will be amortized from accumulated other comprehensive income into net periodic benefit cost during the next fiscal year
Estimated net actuarial (gain) loss that will be amortized from accumulated other comprehensive income into net periodic benefit cost during the next fiscal year		0
Estimated prior service cost (benefit) that will be amortized from accumulated other comprehensive income into net periodic benefit cost during the next fiscal year		$ (34.6)
Retiree health benefits
Defined Benefit Plan Disclosures
Participant contributions as a percent of expected cost of coverage for employees hired prior to January 1, 2002, and who retired on or after January 1, 2011 (as a percent)		60.00%

Employee and Agent Benefits - W

Employee and Agent Benefits - Weighted Average Assumptions (Details) - USD ($) $ in Millions	2 Months Ended	10 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension benefits
Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section
Discount rate: Benefit obligation (as a percent)	4.15%		4.15%	4.50%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate: Net periodic benefit cost (as a percent)			4.50%	4.00%	4.90%
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)			7.20%	7.20%	6.75%
Pension benefits, Cash balance benefit
Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section
Rate of compensation increase: Benefit obligation (as a percent)	5.02%		5.02%	5.24%
Weighted-average assumptions used to determine net periodic benefit cost
Rate of compensation increase: Net periodic benefit cost (as a percent)			5.24%	5.25%	5.29%
Pension benefits, Traditional benefit
Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section
Rate of compensation increase: Benefit obligation (as a percent)	2.70%		2.70%	2.98%
Weighted-average assumptions used to determine net periodic benefit cost
Rate of compensation increase: Net periodic benefit cost (as a percent)			2.98%	3.02%	3.06%
Other postretirement benefits
Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section
Discount rate: Benefit obligation (as a percent)	3.75%		3.75%	4.15%
Rate of compensation increase: Benefit obligation (as a percent)	2.44%		2.44%	4.82%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate: Net periodic benefit cost (as a percent)	3.35%	4.15%		4.00%	4.90%
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)			5.24%	5.36%	5.36%
Rate of compensation increase: Net periodic benefit cost (as a percent)			4.82%	4.82%	4.83%
Assumed Health Care Cost Trend Rates
Health care cost trend rate assumed for next year under age 65 (as a percent)			7.00%	7.00%
Health care cost trend rate assumed for next year age 65 and over (as a percent)			6.00%	6.00%
Rate to which the health care cost trend rate is assumed to decline (the ultimate trend rate) (as a percent)			4.50%	4.50%
Year that the health care cost trend rate reaches the ultimate trend rate under age 65 (calendar year)			2,023	2,019
Year that the health care cost trend rate reaches the ultimate trend rate age 65 and over (calendar year)			2,021	2,020
Effect of one-percentage-point change in assumed health care cost trend rates
Effect on total of service cost and interest cost components of a one-percentage-point increase in assumed health care cost trend rates			$ 0.5
Effect on total of service cost and interest cost components of a one-percentage-point decrease in assumed health care cost trend rates			(0.4)
Effect on accumulated postretirement benefit obligation of a one-percentage-point increase in assumed health care cost trend rates			(1.6)
Effect on accumulated postretirement benefit obligation of a one-percentage-point decrease in assumed health care cost trend rates			$ 1.5
Medical plans
Weighted-average assumptions used to determine net periodic benefit cost
Expected long-term return on plan assets: Net periodic benefit cost, under age 65 (as a percent)			5.20%
Expected long-term return on plan assets: Net periodic benefit cost, age 65 and over (as a percent)			5.10%
Life plans
Weighted-average assumptions used to determine net periodic benefit cost
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)			5.70%
Long-term care plans
Weighted-average assumptions used to determine net periodic benefit cost
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)			4.25%

Employee and Agent Benefits - F

Employee and Agent Benefits - Fair Value of Plan Assets by Asset Category (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension benefits
Defined benefit plan, fair value of plan assets
Fair value of plan assets	$ 2,190.8	$ 2,166.3	$ 2,218.3
Qualified defined benefit pension plans
Defined benefit plan, fair value of plan assets
Fair value of plan assets	2,190.8	2,166.3
Qualified defined benefit pension plans | U.S. large cap equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	772.7	591.2
Qualified defined benefit pension plans | U.S. small/mid cap equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	153	138
Qualified defined benefit pension plans | Balanced asset allocation portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	123	119.9
Qualified defined benefit pension plans | International equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	294.3	201.7
Qualified defined benefit pension plans | Fixed income security portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	718.4	997
Qualified defined benefit pension plans | Real estate investment portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	129.4	118.5
Qualified defined benefit pension plans | Fair value hierarchy Level 2
Defined benefit plan, fair value of plan assets
Fair value of plan assets	2,190.8	2,166.3
Qualified defined benefit pension plans | Fair value hierarchy Level 2 | U.S. large cap equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	772.7	591.2
Qualified defined benefit pension plans | Fair value hierarchy Level 2 | U.S. small/mid cap equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	153	138
Qualified defined benefit pension plans | Fair value hierarchy Level 2 | Balanced asset allocation portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	123	119.9
Qualified defined benefit pension plans | Fair value hierarchy Level 2 | International equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	294.3	201.7
Qualified defined benefit pension plans | Fair value hierarchy Level 2 | Fixed income security portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	718.4	997
Qualified defined benefit pension plans | Fair value hierarchy Level 2 | Real estate investment portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	129.4	118.5
Qualified defined benefit pension plans | Fair value hierarchy Level 3
Defined benefit plan, fair value of plan assets
Fair value of plan assets	0	0	0
Other postretirement benefits
Defined benefit plan, fair value of plan assets
Fair value of plan assets	628.6	627	639.7
Fair value of plan assets included in trust owned life insurance contract	81.8	81.2
Other postretirement benefits | Cash and cash equivalents
Defined benefit plan, fair value of plan assets
Fair value of plan assets	1.2	5.9
Other postretirement benefits | U.S. equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	145.5	339.6
Other postretirement benefits | International equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	51.2	66.3
Other postretirement benefits | Fixed income investment funds
Defined benefit plan, fair value of plan assets
Fair value of plan assets	195.5	181.7
Other postretirement benefits | Principal Life general account investment
Defined benefit plan, fair value of plan assets
Fair value of plan assets		33.5
Other postretirement benefits | Alternative mutual fund portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	227.5
Other postretirement benefits | Real estate mutual fund
Defined benefit plan, fair value of plan assets
Fair value of plan assets	7.7
Other postretirement benefits | Fair value hierarchy Level 1
Defined benefit plan, fair value of plan assets
Fair value of plan assets	547.1	512.3
Other postretirement benefits | Fair value hierarchy Level 1 | Cash and cash equivalents
Defined benefit plan, fair value of plan assets
Fair value of plan assets	1.2	5.9
Other postretirement benefits | Fair value hierarchy Level 1 | U.S. equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	103.2	278.8
Other postretirement benefits | Fair value hierarchy Level 1 | International equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	43.2	54.4
Other postretirement benefits | Fair value hierarchy Level 1 | Fixed income investment funds
Defined benefit plan, fair value of plan assets
Fair value of plan assets	164.3	173.2
Other postretirement benefits | Fair value hierarchy Level 1 | Alternative mutual fund portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	227.5
Other postretirement benefits | Fair value hierarchy Level 1 | Real estate mutual fund
Defined benefit plan, fair value of plan assets
Fair value of plan assets	7.7
Other postretirement benefits | Fair value hierarchy Level 2
Defined benefit plan, fair value of plan assets
Fair value of plan assets	81.5	81.2
Other postretirement benefits | Fair value hierarchy Level 2 | U.S. equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	42.3	60.8
Other postretirement benefits | Fair value hierarchy Level 2 | International equity portfolios
Defined benefit plan, fair value of plan assets
Fair value of plan assets	8	11.9
Other postretirement benefits | Fair value hierarchy Level 2 | Fixed income investment funds
Defined benefit plan, fair value of plan assets
Fair value of plan assets	$ 31.2	8.5
Other postretirement benefits | Fair value hierarchy Level 3
Defined benefit plan, fair value of plan assets
Fair value of plan assets		33.5
Other postretirement benefits | Fair value hierarchy Level 3 | Principal Life general account investment
Defined benefit plan, fair value of plan assets
Fair value of plan assets		$ 33.5	$ 36.3	$ 38.8

Employee and Agent Benefits - R

Employee and Agent Benefits - Reconciliation of Fair Value of Plan Assets using Level 3 Inputs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension benefits
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	$ 2,166.3	$ 2,218.3
Fair value of plan assets at end of year	2,190.8	2,166.3	$ 2,218.3
Qualified defined benefit pension plans
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	2,166.3
Fair value of plan assets at end of year	2,190.8	2,166.3
Qualified defined benefit pension plans | Fixed income security portfolios
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	997
Fair value of plan assets at end of year	718.4	997
Qualified defined benefit pension plans | Real estate investment portfolios
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	118.5
Fair value of plan assets at end of year	129.4	118.5
Qualified defined benefit pension plans | Fair value hierarchy Level 3
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	0	0
Fair value of plan assets at end of year	0	0	0
Other postretirement benefits
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	627	639.7
Fair value of plan assets at end of year	628.6	627	639.7
Other postretirement benefits | Principal Life general account investment
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	33.5
Fair value of plan assets at end of year		33.5
Other postretirement benefits | Fair value hierarchy Level 3
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	33.5
Fair value of plan assets at end of year		33.5
Other postretirement benefits | Fair value hierarchy Level 3 | Principal Life general account investment
Change in Level 3 fair value measurement rollforward, plan assets
Fair value of plan assets at beginning of year	33.5	36.3	38.8
Actual return gains (losses) on plan assets relating to assets still held at the reporting date	(1.7)	0.2	0.8
Actual return gains (losses) on plan assets relating to assets sold during the period	(33.6)
Net purchases, sales and settlements	$ 1.8	(3)	(3.3)
Fair value of plan assets at end of year		$ 33.5	$ 36.3

Employee and Agent Benefits - T

Employee and Agent Benefits - Target Plan Asset Allocation (Details)	12 Months Ended
	Dec. 31, 2016
Qualified defined benefit pension plans | U.S. equity portfolios | Minimum
Asset category target allocation
Asset category target allocation	0
Qualified defined benefit pension plans | U.S. equity portfolios | Maximum
Asset category target allocation
Asset category target allocation	45
Qualified defined benefit pension plans | International equity portfolios | Minimum
Asset category target allocation
Asset category target allocation	0
Qualified defined benefit pension plans | International equity portfolios | Maximum
Asset category target allocation
Asset category target allocation	15
Qualified defined benefit pension plans | Fixed income security portfolios | Minimum
Asset category target allocation
Asset category target allocation	30
Qualified defined benefit pension plans | Fixed income security portfolios | Maximum
Asset category target allocation
Asset category target allocation	100
Qualified defined benefit pension plans | Real estate investment portfolios | Minimum
Asset category target allocation
Asset category target allocation	0
Qualified defined benefit pension plans | Real estate investment portfolios | Maximum
Asset category target allocation
Asset category target allocation	10
Other postretirement benefits | U.S. equity portfolios
Asset category target allocation
Asset category target allocation	24
Other postretirement benefits | International equity portfolios
Asset category target allocation
Asset category target allocation	15
Other postretirement benefits | Fixed income security portfolios
Asset category target allocation
Asset category target allocation	32
Other postretirement benefits | Alternative mutual fund portfolios
Asset category target allocation
Asset category target allocation	24
Other postretirement benefits | Real estate investment portfolios
Asset category target allocation
Asset category target allocation	5

Employee and Agent Benefits - E

Employee and Agent Benefits - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2016USD ($)
Pension benefits
Contributions
The high end of the range of possible contributions to be made during the next fiscal year to the qualified and nonqualified pension plans combined	$ 125
Estimated Future Benefit Payments
Estimated future benefit payments, Year 1	115.1
Estimated future benefit payments, Year 2	125.2
Estimated future benefit payments, Year 3	128.2
Estimated future benefit payments, Year 4	137.7
Estimated future benefit payments, Year 5	143.5
Estimated future benefit payments, Years 6-10	832.2
Other postretirement benefits
Estimated Future Benefit Payments
Estimated future benefit payments, Year 1	12.8
Estimated future benefit payments, Year 2	13.2
Estimated future benefit payments, Year 3	13.6
Estimated future benefit payments, Year 4	12.6
Estimated future benefit payments, Year 5	11.5
Estimated future benefit payments, Years 6-10	10.7
Amount of Medicare Part D subsidy receipts
Medicare Part D subsidy receipts, Year 1	0.1
Medicare Part D subsidy receipts, Year 2	0.1
Medicare Part D subsidy receipts, Year 3	0.1
Medicare Part D subsidy receipts, Year 4	0.1
Medicare Part D subsidy receipts, Year 5	0.1
Medicare Part D subsidy receipts, Years 6-10	$ 0.1

Employee and Agent Benefits - S

Employee and Agent Benefits - Supplemental Information, Qualified and Nonqualified Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension benefits
Amount recognized in statement of financial position
Amount recognized in other liabilities	$ (865.4)	$ (885.9)
Total assets (liabilities) recognized in statement of financial position	(865.4)	(885.9)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	706.9	771.2
Prior service (benefit) cost	(2.9)	(5.1)
Pre-tax accumulated other comprehensive (income) loss	704	766.1
Components of Net Periodic Benefit Cost (Income)
Service cost	65	63.2	$ 54
Interest cost	134.9	120.3	117.1
Expected return on plan assets	(155)	(160.6)	(131.9)
Amortization of prior service (benefit) cost	(2.2)	(1.9)	(4.7)
Recognized net actuarial (gain) loss	77	102.4	50.5
Net periodic benefit cost (income)	119.7	123.4	$ 85
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	12.7	114.3
Amortization of net gain (loss)	(77)	(102.4)
Amortization of prior service benefit (cost)	2.2	1.9
Total recognized in pre-tax accumulated other comprehensive (income) loss	(62.1)	13.8
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	57.6	137.2
Qualified defined benefit pension plans
Amount recognized in statement of financial position
Amount recognized in other liabilities	(410)	(453)
Total assets (liabilities) recognized in statement of financial position	(410)	(453)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	587.5	659
Prior service (benefit) cost	(1.6)	(2.6)
Pre-tax accumulated other comprehensive (income) loss	585.9	656.4
Components of Net Periodic Benefit Cost (Income)
Service cost	58.1	54.8
Interest cost	115.9	102.3
Expected return on plan assets	(155)	(160.6)
Amortization of prior service (benefit) cost	(1.1)	(0.8)
Recognized net actuarial (gain) loss	69.5	86.3
Net periodic benefit cost (income)	87.4	82
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	(2)	142.1
Amortization of net gain (loss)	(69.5)	(86.3)
Amortization of prior service benefit (cost)	1.1	0.8
Total recognized in pre-tax accumulated other comprehensive (income) loss	(70.4)	56.6
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	17	138.6
Nonqualified defined benefit pension plans
Amount recognized in statement of financial position
Amount recognized in other liabilities	(455.4)	(432.9)
Total assets (liabilities) recognized in statement of financial position	(455.4)	(432.9)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	119.4	112.2
Prior service (benefit) cost	(1.3)	(2.5)
Pre-tax accumulated other comprehensive (income) loss	118.1	109.7
Components of Net Periodic Benefit Cost (Income)
Service cost	6.9	8.4
Interest cost	19	18
Amortization of prior service (benefit) cost	(1.1)	(1.1)
Recognized net actuarial (gain) loss	7.5	16.1
Net periodic benefit cost (income)	32.3	41.4
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	14.7	(27.8)
Amortization of net gain (loss)	(7.5)	(16.1)
Amortization of prior service benefit (cost)	1.1	1.1
Total recognized in pre-tax accumulated other comprehensive (income) loss	8.3	(42.8)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$ 40.6	$ (1.4)

Employee and Agent Benefits - P

Employee and Agent Benefits - Plan Eligibility and Contribution Information (Details) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Plan Disclosures
Number of common stock shares allocated participants in the employee stock ownership plan	2.4	2.4
Fair value of employee stock ownership plan	$ 137,900,000	$ 108,400,000
Qualified defined contribution plan
Defined Contribution Plan Disclosures
Maximum amount of compensation eligible participants could contribute to defined contribution plans	18,000
Amount contributed by the employer to defined contribution plans	$ 46,600,000	45,700,000	$ 41,700,000
Qualified defined contribution plan | Grandfathered Choice Participant
Defined Contribution Plan Disclosures
Eligibility age to be able to elect to retain benefits in defined contribution plan	47 years
Minimum years of service to be able to elect to retain benefits in defined contribution plan	10 years
Contribution rate of employer to match participant's contributions (as a percent)	50.00%
Maximum percent of participant's compensation matched by employer (as a percent)	3.00%
Qualified defined contribution plan | All other participants
Defined Contribution Plan Disclosures
Contribution rate of employer to match participant's contributions (as a percent)	75.00%
Maximum percent of participant's compensation matched by employer (as a percent)	6.00%
Nonqualified deferred compensation plan
Defined Contribution Plan Disclosures
Amount contributed by the employer to defined contribution plans	$ 3,300,000	$ 4,500,000	$ 4,100,000
Nonqualified deferred compensation plan | Grandfathered Choice Participant
Defined Contribution Plan Disclosures
Contribution rate of employer to match participant's contributions (as a percent)	50.00%
Maximum percent of participant's compensation matched by employer (as a percent)	3.00%
Nonqualified deferred compensation plan | All other participants
Defined Contribution Plan Disclosures
Contribution rate of employer to match participant's contributions (as a percent)	75.00%
Maximum percent of participant's compensation matched by employer (as a percent)	6.00%

Contingencies, Guarantees an114

Contingencies, Guarantees and Indemnifications - Litigation and Regulatory Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2008
Loss contingencies - disclosures
Proceeds from termination of certain structured transactions and the resulting prepayment			$ 440
Amount, including interest, attempted to be recovered	$ 600
Estimated losses accrued related to legal matters	0
Maximum exposure under guarantees	172
Guaranty Funds
Undiscounted liability balance for guaranty fund assessments	14.9	$ 15.1
Premium tax offsets	$ 5.7	$ 5.7

Contingencies, Guarantees an115

Contingencies, Guarantees and Indemnifications - Operating and Capital Lease Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating leases
Operating lease rental expense	$ 40.4	$ 38	$ 37.3
Operating lease obligations
Year 1: Operating lease obligations	45.2
Year 2: Operating lease obligations	32.4
Year 3: Operating lease obligations	22.3
Year 4: Operating lease obligations	15.6
Year 5: Operating lease obligations	11.3
Year 6 and thereafter: Operating lease obligations	37.6
Total operating lease obligations	164.4
Less: Future sublease rental income on noncancelable leases	2.3
Total future minimum lease payments	162.1
Capital leases
Capital lease gross asset balance	61.3	63.6
Capital lease accumulated depreciation	29.9	29.9
Capital lease depreciation expense	14.8	$ 14.1	$ 14
Capital lease future minimum lease payments
Year 1: Capital lease future minimum lease payments	3
Year 2: Capital lease future minimum lease payments	2.1
Year 3: Capital lease future minimum lease payments	0.9
Year 4: Capital lease future minimum lease payments	0.4
Year 5: Capital lease future minimum lease payments	0.1
Year 6 and thereafter: Capital lease future minimum lease payments	0.2
Total capital lease future minimum lease payments	6.7
Less: Amounts representing interest	0.2
Net present value of minimum lease payments	$ 6.5

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock and Dividend Payments (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jun. 30, 2015	Mar. 30, 2015	Dec. 30, 2014	Sep. 30, 2014	Jun. 30, 2014	Apr. 01, 2014	Feb. 29, 2016	Oct. 31, 2015	Feb. 28, 2015	Feb. 28, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Preferred Stock
Preferred stock redemption												$ 550
Excess of redemption value over carrying value of preferred shares redeemed												8.2
Dividends to preferred stockholders												$ 16.5	$ 33
Preferred stock
Preferred Stock
Excess of redemption value over carrying value of preferred shares redeemed	$ 8.2
Dividends to preferred stockholders	$ 8.3	$ 8.2	$ 8.3	$ 8.2	$ 8.3	$ 8.2
Common stock
Reconciliation of Outstanding Shares
Outstanding shares at beginning of period											291.4	293.9	295.2
Shares issued											3	3.5	3.4
Treasury stock acquired											(6.7)	(6)	(4.7)
Outstanding shares at end of period											287.7	291.4	293.9
Common stock share repurchase disclosures
Share repurchase program, maximum authorized amount (in dollars)							$ 400	$ 150	$ 150	$ 200
Series A | Preferred stock
Preferred Stock
Preferred stock redemption (in shares)	3											3
Preferred stock redemption	$ 300
Preferred stock dividend (in dollars per share)	$ 1.39	$ 1.39	$ 1.39	$ 1.39	$ 1.39	$ 1.39
Reconciliation of Outstanding Shares
Outstanding shares at beginning of period												3	3
Preferred stock redemption	(3)											(3)
Outstanding shares at end of period													3
Series B | Preferred stock
Preferred Stock
Preferred stock redemption (in shares)	10											10
Preferred stock redemption	$ 250											$ 0.1
Preferred stock dividend (in dollars per share)	$ 0.41	$ 0.41	$ 0.41	$ 0.41	$ 0.41	$ 0.41
Reconciliation of Outstanding Shares
Outstanding shares at beginning of period												10	10
Preferred stock redemption	(10)											(10)
Outstanding shares at end of period													10

Stockholders' Equity - Other Co

Stockholders' Equity - Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income (Loss)
Other comprehensive income (loss), pre-tax	$ 317.6	$ (1,263.9)	$ (115.6)
Other comprehensive income (loss), tax	(96.6)	320.8	(28.5)
Other comprehensive income (loss)	221	(943.1)	(144.1)
Net unrealized gains (losses) on available-for-sale securities including NCI
Other Comprehensive Income (Loss)
Other comprehensive income (loss) before reclassifications, pre-tax	254.6	(1,713.7)	1,087.9
Adjustments for assumed changes in amortization patterns, pre-tax	5.6	201.2	(63.4)
Adjustments for assumed changes in policyholder liabilities, pre-tax	(177.2)	779	(458.4)
Other comprehensive income (loss), pre-tax	150.9	(718.4)	492.9
Other comprehensive income (loss) before reclassifications, tax	(78.1)	589	(425.2)
Reclassification from accumulated other comprehensive income, tax	(23.5)	(5.4)	24.4
Adjustments for assumed changes in amortization patterns, tax	(2)	(70.4)	22.2
Adjustments for assumed changes in policyholder liabilities, tax	51.8	(265.5)	210.4
Other comprehensive income (loss), tax	(51.8)	247.7	(168.2)
Other comprehensive income (loss) before reclassifications, after-tax	176.5	(1,124.7)	662.7
Reclassification from accumulated other comprehensive income, after-tax	44.4	9.7	(48.8)
Adjustments for assumed changes in amortization patterns, after-tax	3.6	130.8	(41.2)
Adjustments for assumed changes in policyholder liabilities, after-tax	(125.4)	513.5	(248)
Other comprehensive income (loss)	99.1	(470.7)	324.7
Net unrealized gains (losses) on available-for-sale securities including NCI | Net realized capital gains (losses)
Other Comprehensive Income (Loss)
Reclassification from accumulated other comprehensive income, pre-tax	67.9	15.1	(73.2)
Noncredit component of impairment losses on fixed maturities available-for-sale including NCI
Other Comprehensive Income (Loss)
Other comprehensive income (loss) before reclassifications, pre-tax	(0.3)	29.4	102
Adjustments for assumed changes in amortization patterns, pre-tax	(3.4)	(0.9)	(4.7)
Adjustments for assumed changes in policyholder liabilities, pre-tax	0.8	0.7	(2.2)
Other comprehensive income (loss), pre-tax	(2.9)	29.2	95.1
Other comprehensive income (loss) before reclassifications, tax	(1.5)	(10.2)	(35.6)
Adjustments for assumed changes in amortization patterns, tax	1.2	0.3	1.7
Adjustments for assumed changes in policyholder liabilities, tax	(0.3)	(0.2)	0.7
Other comprehensive income (loss), tax	(0.6)	(10.1)	(33.2)
Other comprehensive income (loss) before reclassifications, after-tax	(1.8)	19.2	66.4
Adjustments for assumed changes in amortization patterns, after-tax	(2.2)	(0.6)	(3)
Adjustments for assumed changes in policyholder liabilities, after-tax	0.5	0.5	(1.5)
Other comprehensive income (loss)	(3.5)	19.1	61.9
Net unrealized gains (losses) on derivative instruments including NCI
Other Comprehensive Income (Loss)
Other comprehensive income (loss) before reclassifications, pre-tax	32.6	58.4	100.3
Reclassification from accumulated other comprehensive income, pre-tax	(27.7)	(36.9)	3.8
Adjustments for assumed changes in amortization patterns, pre-tax	2.9	19.5	(12.8)
Adjustments for assumed changes in policyholder liabilities, pre-tax	16.9	(10.8)	3.2
Other comprehensive income (loss), pre-tax	24.7	30.2	94.5
Other comprehensive income (loss) before reclassifications, tax	(7.6)	(20.4)	(35.1)
Reclassification from accumulated other comprehensive income, tax	5.4	12.5	(1.7)
Adjustments for assumed changes in amortization patterns, tax	(1)	(6.9)	4.5
Adjustments for assumed changes in policyholder liabilities, tax	(6)	3.8	(1.1)
Other comprehensive income (loss), tax	(9.2)	(11)	(33.4)
Other comprehensive income (loss) before reclassifications, after-tax	25	38	65.2
Reclassification from accumulated other comprehensive income, after-tax	(22.3)	(24.4)	2.1
Adjustments for assumed changes in amortization patterns, after-tax	1.9	12.6	(8.3)
Adjustments for assumed changes in policyholder liabilities, after-tax	10.9	(7)	2.1
Other comprehensive income (loss)	15.5	19.2	61.1
Foreign currency translation adjustment including NCI
Other Comprehensive Income (Loss)
Other comprehensive income (loss), pre-tax	75.6	(543.6)	(374.7)
Other comprehensive income (loss), tax	(7.5)	72	38.1
Other comprehensive income (loss)	68.1	(471.6)	(336.6)
Unrecognized postretirement benefit obligation including NCI
Other Comprehensive Income (Loss)
Other comprehensive income (loss) before reclassifications, pre-tax	20.2	(142.5)	(445.5)
Other comprehensive income (loss), pre-tax	69.3	(61.3)	(423.4)
Other comprehensive income (loss) before reclassifications, tax	(6.8)	55.5	176.3
Reclassification from accumulated other comprehensive income, tax	(20.7)	(33.3)	(8.1)
Other comprehensive income (loss), tax	(27.5)	22.2	168.2
Other comprehensive income (loss) before reclassifications, after-tax	13.4	(87)	(269.2)
Reclassification from accumulated other comprehensive income, after-tax	28.4	47.9	14
Other comprehensive income (loss)	41.8	(39.1)	(255.2)
Unrecognized postretirement benefit obligation including NCI | Operating expense
Other Comprehensive Income (Loss)
Reclassification from accumulated other comprehensive income, pre-tax	$ 49.1	$ 81.2	$ 22.1

Stockholders' Equity - AOCI and

Stockholders' Equity - AOCI and Noncontrolling Interest (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in accumulated other comprehensive income (loss) rollforward
Balances		$ 9,311.6
Purchase of subsidiary shares from noncontrolling interest	[1]	5.8	$ (16.5)	$ (47.6)
Balances		10,227.3	9,311.6
Change in redeemable noncontrolling interest rollforward
Redeemable noncontrolling interest, balance at beginning of period		85.7	58	247.2
Net income (loss) attributable to redeemable noncontrolling interest		16.8	4.9	9
Redeemable noncontrolling interest of newly consolidated entities		179.5
Redeemable noncontrolling interest of deconsolidated entities		(261.5)
Contributions from redeemable noncontrolling interest		135.1	56.1	9.5
Distributions to redeemable noncontrolling interest		(57.4)	(15.1)	(16.1)
Purchase of subsidiary shares from redeemable noncontrolling interest		(8.2)	(6)	(215.2)
Change in redemption value of redeemable noncontrolling interest		4.2	6.6	28.9
Other comprehensive income (loss) attributable to redeemable noncontrolling interest		3.3	(18.8)	(5.3)
Redeemable noncontrolling interest, balance at end of period		$ 97.5	85.7	58
Dividend Limitations
Statutory dividend limitation as percentage of policyholder surplus (as a percent)		10.00%
Dividends that can be paid in upcoming calendar year without exceeding statutory limitation		$ 1,143.3
Accumulated other comprehensive income (loss)
Change in accumulated other comprehensive income (loss) rollforward
Balances		(882.5)	50.4	183.2
Other comprehensive income (loss) during the period, net of adjustments		166.1	(974.9)	(162)
Amounts reclassified from accumulated other comprehensive income (loss)		50.5	52.3	29.2
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		216.6	(922.6)	(132.8)
Purchase of subsidiary shares from noncontrolling interest	[1]	(9.3)	(10.3)
Balances		(675.2)	(882.5)	50.4
Net unrealized gains (losses) on available-for-sale securities
Change in accumulated other comprehensive income (loss) rollforward
Balances		732.1	1,202.8	878.1
Other comprehensive income (loss) during the period, net of adjustments		54.7	(480.4)	373.5
Amounts reclassified from accumulated other comprehensive income (loss)		44.4	9.7	(48.8)
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		99.1	(470.7)	324.7
Balances		831.2	732.1	1,202.8
Noncredit component of impairment losses on fixed maturities available-for-sale
Change in accumulated other comprehensive income (loss) rollforward
Balances		(86)	(105.1)	(167)
Other comprehensive income (loss) during the period, net of adjustments		(3.5)
Amounts reclassified from accumulated other comprehensive income (loss)			19.1	61.9
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		(3.5)	19.1	61.9
Balances		(89.5)	(86)	(105.1)
Net unrealized gains (losses) on derivative instruments
Change in accumulated other comprehensive income (loss) rollforward
Balances		69.8	50.6	(10.5)
Other comprehensive income (loss) during the period, net of adjustments		37.8	43.6	59
Amounts reclassified from accumulated other comprehensive income (loss)		(22.3)	(24.4)	2.1
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		15.5	19.2	61.1
Balances		85.3	69.8	50.6
Foreign currency translation adjustment
Change in accumulated other comprehensive income (loss) rollforward
Balances		(1,148.2)	(686.8)	(361.5)
Other comprehensive income (loss) during the period, net of adjustments		63.7	(451.1)	(325.3)
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		63.7	(451.1)	(325.3)
Purchase of subsidiary shares from noncontrolling interest		(9.3)	(10.3)
Balances		(1,093.8)	(1,148.2)	(686.8)
Unrecognized postretirement benefit obligation
Change in accumulated other comprehensive income (loss) rollforward
Balances		(450.2)	(411.1)	(155.9)
Other comprehensive income (loss) during the period, net of adjustments		13.4	(87)	(269.2)
Amounts reclassified from accumulated other comprehensive income (loss)		28.4	47.9	14
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		41.8	(39.1)	(255.2)
Balances		$ (408.4)	$ (450.2)	$ (411.1)
[1]	Excludes amounts attributable to redeemable noncontrolling interest. See Note 13, Stockholders’ Equity, for further details.

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Assets (liabilities) measured at fair value on a recurring basis
Derivative instruments, assets	$ 893.6	$ 666.6
Separate account assets	139,832.6	136,978.9
Investment contracts	(176.5)	(177.4)
Unfunded commitments of investments measured using NAV	$ 57.6	7.3
Fixed maturities valued using internal pricing models
Fixed maturities classified as Level 3 assets, percent valued using internal pricing models (as a percent)	1.00%
Fixed maturities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	$ 54,846.1	49,966.5
U.S. government and agencies
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	1,433	1,503.5
Non-U.S. governments
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	893.6	793.3
States and political subdivisions
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	5,569.2	4,717.1
Corporate debt securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	34,192.4	31,140.2
Residential mortgage-backed pass-through securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	2,834.7	2,627.5
Commercial mortgage-backed securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	4,096.5	3,919.8
Collateralized debt obligations
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	758.6	667.5
Other debt obligations
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	5,068.1	4,597.6
Equity securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	98.9	104.5
Recurring Fair Value Measurements
Assets (liabilities) measured at fair value on a recurring basis
Derivative instruments, assets	893.6	666.6
Other investments	470	517.2
Other investments net asset value	92.7	69.6
Cash equivalents	1,947.1	1,603.2
Sub-total excluding separate account assets	60,067.5	54,747.5
Sub-total excluding separate account assets net asset value	92.7	69.6
Separate account assets	139,832.6	136,978.9
Total assets	199,900.1	191,726.4
Total assets net asset value	92.7	69.6
Investment contracts	(176.5)	(177.4)
Derivative liabilities	(573)	(772.4)
Other liabilities	(272.2)	(298.4)
Total liabilities	(1,021.7)	(1,248.2)
Net assets (liabilities)	198,878.4	190,478.2
Net assets (liabilities) net asset value	92.7	69.6
Recurring Fair Value Measurements | Fair value hierarchy Level 1
Assets (liabilities) measured at fair value on a recurring basis
Other investments	169.8	208.1
Cash equivalents	51.2	26.5
Sub-total excluding separate account assets	1,742.6	1,882.1
Separate account assets	79,688.1	72,303.6
Total assets	81,430.7	74,185.7
Net assets (liabilities)	81,430.7	74,185.7
Recurring Fair Value Measurements | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Derivative instruments, assets	859.7	619.4
Other investments	170.6	204.4
Cash equivalents	1,895.9	1,576.7
Sub-total excluding separate account assets	57,548.4	52,195.1
Separate account assets	52,789.7	57,661.4
Total assets	110,338.1	109,856.5
Derivative liabilities	(550.4)	(721.9)
Other liabilities	(212.3)	(230.3)
Total liabilities	(762.7)	(952.2)
Net assets (liabilities)	109,575.4	108,904.3
Recurring Fair Value Measurements | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Derivative instruments, assets	33.9	47.2
Other investments	36.9	35.1
Sub-total excluding separate account assets	683.8	600.7
Separate account assets	7,354.8	7,013.9
Total assets	8,038.6	7,614.6
Investment contracts	(176.5)	(177.4)
Derivative liabilities	(22.6)	(50.5)
Other liabilities	(59.9)	(68.1)
Total liabilities	(259)	(296)
Net assets (liabilities)	7,779.6	7,318.6
Recurring Fair Value Measurements | Fixed maturities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	54,846.1	49,966.5
Trading	398.4	686.8
Recurring Fair Value Measurements | Fixed maturities | Fair value hierarchy Level 1
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	1,020.7	972.2
Trading		199.2
Recurring Fair Value Measurements | Fixed maturities | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	53,308	48,615.5
Trading	305.5	352.1
Recurring Fair Value Measurements | Fixed maturities | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	517.4	378.8
Trading	92.9	135.5
Recurring Fair Value Measurements | U.S. government and agencies
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	1,433	1,503.5
Recurring Fair Value Measurements | U.S. government and agencies | Fair value hierarchy Level 1
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	996.5	931
Recurring Fair Value Measurements | U.S. government and agencies | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	436.5	572.5
Recurring Fair Value Measurements | Non-U.S. governments
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	893.6	793.3
Recurring Fair Value Measurements | Non-U.S. governments | Fair value hierarchy Level 1
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	3	3
Recurring Fair Value Measurements | Non-U.S. governments | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	828.5	711.2
Recurring Fair Value Measurements | Non-U.S. governments | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	62.1	79.1
Recurring Fair Value Measurements | States and political subdivisions
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	5,569.2	4,717.1
Recurring Fair Value Measurements | States and political subdivisions | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	5,569.2	4,717.1
Recurring Fair Value Measurements | Corporate debt securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	34,192.4	31,140.2
Recurring Fair Value Measurements | Corporate debt securities | Fair value hierarchy Level 1
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	21.2	38.2
Recurring Fair Value Measurements | Corporate debt securities | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	33,912.1	30,878.1
Recurring Fair Value Measurements | Corporate debt securities | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	259.1	223.9
Recurring Fair Value Measurements | Residential mortgage-backed pass-through securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	2,834.7	2,627.5
Recurring Fair Value Measurements | Residential mortgage-backed pass-through securities | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	2,834.7	2,627.5
Recurring Fair Value Measurements | Commercial mortgage-backed securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	4,096.5	3,919.8
Recurring Fair Value Measurements | Commercial mortgage-backed securities | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	4,025.4	3,915
Recurring Fair Value Measurements | Commercial mortgage-backed securities | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	71.1	4.8
Recurring Fair Value Measurements | Collateralized debt obligations
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	758.6	667.5
Recurring Fair Value Measurements | Collateralized debt obligations | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	725	604
Recurring Fair Value Measurements | Collateralized debt obligations | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	33.6	63.5
Recurring Fair Value Measurements | Other debt obligations
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	5,068.1	4,597.6
Recurring Fair Value Measurements | Other debt obligations | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	4,976.6	4,590.1
Recurring Fair Value Measurements | Other debt obligations | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	91.5	7.5
Recurring Fair Value Measurements | Equity securities
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	98.9	104.5
Trading	1,413.4	1,202.7
Recurring Fair Value Measurements | Equity securities | Fair value hierarchy Level 1
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	55.2	62.2
Trading	445.7	413.9
Recurring Fair Value Measurements | Equity securities | Fair value hierarchy Level 2
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	41	38.2
Trading	967.7	788.8
Recurring Fair Value Measurements | Equity securities | Fair value hierarchy Level 3
Assets (liabilities) measured at fair value on a recurring basis
Available-for-sale	$ 2.7	$ 4.1

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 Fair Value Measurements (Details) - Recurring Fair Value Measurements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale | Fixed maturities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	$ 378.8	$ 412.2	$ 336.8
Total realized/unrealized gains (losses) included in net income, assets	(10.8)	(0.4)	(3.3)
Total realized/unrealized gains (losses) included in other comprehensive income, assets	8.3	(4.1)	1.8
Net purchases, sales, issuances and settlements, assets	143.2	87.4	95.4
Transfers into Level 3, assets	51.1	42.8	57.3
Transfers out of Level 3, assets	(53.2)	(159.1)	(75.8)
Ending balance, assets	517.4	378.8	412.2
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	(10.8)	(0.6)	(1.8)
Gross purchases, sales, issuances and settlements
Purchases, assets	226	124.1	211.1
Sales, assets	(19.4)	(7.8)	(80)
Settlements, assets	(63.4)	(28.9)	(35.7)
Net purchases, sales, issuances and settlements, assets	143.2	87.4	95.4
Available-for-sale | Non-U.S. governments
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	79.1	38.7	47.5
Total realized/unrealized gains (losses) included in net income, assets	(0.3)	(0.2)	(0.3)
Total realized/unrealized gains (losses) included in other comprehensive income, assets	1.4	(0.4)
Net purchases, sales, issuances and settlements, assets	14.5	41	(8.5)
Transfers out of Level 3, assets	(32.6)
Ending balance, assets	62.1	79.1	38.7
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	(0.3)	(0.2)	(0.2)
Gross purchases, sales, issuances and settlements
Purchases, assets	19.3	42.4	12.1
Sales, assets	(3.4)	(0.1)	(19.4)
Settlements, assets	(1.4)	(1.3)	(1.2)
Net purchases, sales, issuances and settlements, assets	14.5	41	(8.5)
Available-for-sale | States and political subdivisions
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets			1.8
Net purchases, sales, issuances and settlements, assets			(0.1)
Transfers out of Level 3, assets			(1.7)
Gross purchases, sales, issuances and settlements
Settlements, assets			(0.1)
Net purchases, sales, issuances and settlements, assets			(0.1)
Available-for-sale | Corporate debt securities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	223.9	245.6	164
Total realized/unrealized gains (losses) included in net income, assets	(2.2)	(0.3)	(1.8)
Total realized/unrealized gains (losses) included in other comprehensive income, assets	(3.2)	(4.4)	(1.3)
Net purchases, sales, issuances and settlements, assets	26.6	27.7	56
Transfers into Level 3, assets	15.7	42.8	46.6
Transfers out of Level 3, assets	(1.7)	(87.5)	(17.9)
Ending balance, assets	259.1	223.9	245.6
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	(2.2)	(0.4)	(1.6)
Gross purchases, sales, issuances and settlements
Purchases, assets	66	52.8	118.5
Sales, assets	(13.7)	(7.7)	(54.8)
Settlements, assets	(25.7)	(17.4)	(7.7)
Net purchases, sales, issuances and settlements, assets	26.6	27.7	56
Available-for-sale | Commercial mortgage-backed securities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	4.8		1.6
Total realized/unrealized gains (losses) included in net income, assets	(8.3)	0.1	(1.2)
Total realized/unrealized gains (losses) included in other comprehensive income, assets	8.8		1.3
Net purchases, sales, issuances and settlements, assets	32.7	12.3	(6)
Transfers into Level 3, assets	35.4		6.8
Transfers out of Level 3, assets	(2.3)	(7.6)	(2.5)
Ending balance, assets	71.1	4.8
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	(8.3)
Gross purchases, sales, issuances and settlements
Purchases, assets	35.7	12.4
Sales, assets			(5.8)
Settlements, assets	(3)	(0.1)	(0.2)
Net purchases, sales, issuances and settlements, assets	32.7	12.3	(6)
Available-for-sale | Collateralized debt obligations
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	63.5	64.2	37.8
Total realized/unrealized gains (losses) included in other comprehensive income, assets	0.8	(0.1)	0.4
Net purchases, sales, issuances and settlements, assets	(30.7)	(0.6)	46.1
Transfers into Level 3, assets			3.9
Transfers out of Level 3, assets			(24)
Ending balance, assets	33.6	63.5	64.2
Gross purchases, sales, issuances and settlements
Purchases, assets			61.3
Settlements, assets	(30.7)	(0.6)	(15.2)
Net purchases, sales, issuances and settlements, assets	(30.7)	(0.6)	46.1
Available-for-sale | Other debt obligations
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	7.5	63.7	84.1
Total realized/unrealized gains (losses) included in other comprehensive income, assets	0.5	0.8	1.4
Net purchases, sales, issuances and settlements, assets	100.1	7	7.9
Transfers out of Level 3, assets	(16.6)	(64)	(29.7)
Ending balance, assets	91.5	7.5	63.7
Gross purchases, sales, issuances and settlements
Purchases, assets	105	16.5	19.2
Sales, assets	(2.3)
Settlements, assets	(2.6)	(9.5)	(11.3)
Net purchases, sales, issuances and settlements, assets	100.1	7	7.9
Available-for-sale | Equity securities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	4.1	4.1	16.9
Total realized/unrealized gains (losses) included in net income, assets	(1.3)		4.2
Total realized/unrealized gains (losses) included in other comprehensive income, assets	(0.1)		2.8
Net purchases, sales, issuances and settlements, assets			(20)
Transfers into Level 3, assets			0.2
Ending balance, assets	2.7	4.1	4.1
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	(1.4)		(0.3)
Gross purchases, sales, issuances and settlements
Sales, assets			(20)
Net purchases, sales, issuances and settlements, assets			(20)
Trading | Fixed maturities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	135.5	139.7	169.9
Total realized/unrealized gains (losses) included in net income, assets	0.5	(4)	9.9
Net purchases, sales, issuances and settlements, assets	(43.1)	(0.2)	(40.1)
Ending balance, assets	92.9	135.5	139.7
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	0.1	(4.2)	1.2
Gross purchases, sales, issuances and settlements
Sales, assets	(18)	(0.2)	(10)
Settlements, assets	(25.1)		(30.1)
Net purchases, sales, issuances and settlements, assets	(43.1)	(0.2)	(40.1)
Derivative assets
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	47.2	53.7	74.2
Total realized/unrealized gains (losses) included in net income, assets	(15.1)	(8.7)	(32)
Net purchases, sales, issuances and settlements, assets	1.8	2.2	11.5
Ending balance, assets	33.9	47.2	53.7
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	(12.8)	(8.5)	(32)
Gross purchases, sales, issuances and settlements
Purchases, assets	0.5	2.5	11.8
Sales, assets	1.3	(0.3)	(0.3)
Net purchases, sales, issuances and settlements, assets	1.8	2.2	11.5
Other investments
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	35.1	127.2	142.9
Total realized/unrealized gains (losses) included in net income, assets	1.5	7.3	15.7
Net purchases, sales, issuances and settlements, assets	0.3	(64.4)	(31.4)
Transfers out of Level 3, assets		(35)
Ending balance, assets	36.9	35.1	127.2
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	1.5	7.2	15.7
Gross purchases, sales, issuances and settlements
Purchases, assets	0.7	4.4	0.2
Sales, assets	(0.4)	(68.8)
Settlements, assets			(31.6)
Net purchases, sales, issuances and settlements, assets	0.3	(64.4)	(31.4)
Separate account assets
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, assets	7,013.9	5,891.4	5,265.2
Total realized/unrealized gains (losses) included in net income, assets	718.9	1,054.8	649.6
Net purchases, sales, issuances and settlements, assets	(382.5)	59.5	(13.9)
Transfers into Level 3, assets	5.3	8.5	4.4
Transfers out of Level 3, assets	(0.8)	(0.3)	(13.9)
Ending balance, assets	7,354.8	7,013.9	5,891.4
Changes in unrealized gains (losses) included in net income relating to positions still held, assets	669.7	850.3	608.4
Gross purchases, sales, issuances and settlements
Purchases, assets	528	796.9	705.9
Sales, assets	(654.5)	(436.5)	(500.2)
Issuances, assets	(345.4)	(323.4)	(331.8)
Settlements, assets	89.4	22.5	112.2
Net purchases, sales, issuances and settlements, assets	(382.5)	59.5	(13.9)
Investment contracts
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, liabilities	(177.4)	(176.4)	(6.9)
Total realized/unrealized gains (losses) included in net income, liabilities	(5.9)	(13.4)	(196)
Net purchases, sales, issuances and settlements, liabilities	6.8	12.4	26.5
Ending balance, liabilities	(176.5)	(177.4)	(176.4)
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities	(12.6)	(17.8)	(196.5)
Gross purchases, sales, issuances and settlements
Issuances, liabilities	1.8	5.1	20.7
Settlements, liabilities	5	7.3	5.8
Net purchases, sales, issuances and settlements, liabilities	6.8	12.4	26.5
Derivative liabilities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, liabilities	(50.5)	(35.5)	(39.6)
Total realized/unrealized gains (losses) included in net income, liabilities	26.4	(17.4)	3.9
Total realized/unrealized gains (losses) included in other comprehensive income, liabilities	0.5	2.2	(0.4)
Net purchases, sales, issuances and settlements, liabilities	1	0.2	0.6
Ending balance, liabilities	(22.6)	(50.5)	(35.5)
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities	23.2	(18)	(0.9)
Gross purchases, sales, issuances and settlements
Purchases, liabilities			(1.5)
Sales, liabilities	1	0.2	2.1
Net purchases, sales, issuances and settlements, liabilities	1	0.2	0.6
Other liabilities
Changes in Level 3 fair value measurements rollforward, assets and liabilities
Beginning balance, liabilities	(68.1)	(66.3)	(73.9)
Total realized/unrealized gains (losses) included in net income, liabilities	(9.2)	(1.8)	(1.4)
Net purchases, sales, issuances and settlements, liabilities	17.4		9
Ending balance, liabilities	(59.9)	(68.1)	(66.3)
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities	(7.5)	$ (1.9)	(0.8)
Gross purchases, sales, issuances and settlements
Sales, liabilities	17.4		9
Net purchases, sales, issuances and settlements, liabilities	$ 17.4		$ 9

Fair Value Measurements - Trans

Fair Value Measurements - Transfers (Details) - Recurring Fair Value Measurements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale | Fixed maturities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	$ 51.1	$ 42.8	$ 57.3
Transfers out of Level 3 into Level 2	53.2	159.1	75.8
Available-for-sale | Non-U.S. governments
Fair Value Hierarchy Levels Transfers
Transfers out of Level 3 into Level 2	32.6
Available-for-sale | States and political subdivisions
Fair Value Hierarchy Levels Transfers
Transfers out of Level 3 into Level 2			1.7
Available-for-sale | Corporate debt securities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	15.7	42.8	46.6
Transfers out of Level 3 into Level 2	1.7	87.5	17.9
Available-for-sale | Commercial mortgage-backed securities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3	35.4		6.8
Transfers out of Level 3 into Level 2	2.3	7.6	2.5
Available-for-sale | Collateralized debt obligations
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3			3.9
Transfers out of Level 3 into Level 2			24
Available-for-sale | Other debt obligations
Fair Value Hierarchy Levels Transfers
Transfers out of Level 3 into Level 2	16.6	64	29.7
Available-for-sale | Equity securities
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 3			0.2
Separate account assets
Fair Value Hierarchy Levels Transfers
Transfers out of Level 1 into Level 2	45.4	26.9	33
Transfers out of Level 2 into Level 1	4.9	8.1	71.3
Transfers out of Level 2 into Level 3	5.3	8.5	4.4
Transfers out of Level 3 into Level 2	$ 0.8	0.3	$ 13.9
Other investments
Fair Value Hierarchy Levels Transfers
Transfers out of Level 2 into Level 1		141.4
Transfers out of Level 3 into Level 2		$ 35

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information for Level 3 Measurements (Details) - Recurring Fair Value Measurements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Unobservable inputs
Assets measured at fair value	$ 199,900.1	$ 191,726.4
Liabilities measured at fair value	(1,021.7)	(1,248.2)
Fair value hierarchy Level 3
Unobservable inputs
Assets measured at fair value	8,038.6	7,614.6
Liabilities measured at fair value	(259)	(296)
Fair value hierarchy Level 3 | Available-for-sale | Non-U.S. governments
Unobservable inputs
Assets measured at fair value	$ 7.6	$ 8.9
Fair value hierarchy Level 3 | Available-for-sale | Non-U.S. governments | Discounted cash flow
Unobservable inputs
Discount rate (as a percent)	2.30%	2.20%
Illiquidity premium (as a percent)	0.50%	0.50%
Comparability adjustment (as a percent)	(0.25%)
Fair value hierarchy Level 3 | Available-for-sale | Non-U.S. governments | Discounted cash flow | Weighted average input
Unobservable inputs
Discount rate (as a percent)	2.30%	2.20%
Illiquidity premium (as a percent)	0.50%	0.50%
Comparability adjustment (as a percent)	(0.25%)
Fair value hierarchy Level 3 | Available-for-sale | Corporate debt securities
Unobservable inputs
Assets measured at fair value	$ 49.8	$ 43.2
Fair value hierarchy Level 3 | Available-for-sale | Corporate debt securities | Discounted cash flow | Minimum
Unobservable inputs
Discount rate (as a percent)	1.50%	0.00%
Illiquidity premium (as a percent)	0.00%	0.00%
Comparability adjustment (as a percent)	0.00%	(0.04%)
Fair value hierarchy Level 3 | Available-for-sale | Corporate debt securities | Discounted cash flow | Maximum
Unobservable inputs
Discount rate (as a percent)	7.60%	7.50%
Illiquidity premium (as a percent)	0.60%	0.60%
Comparability adjustment (as a percent)	0.20%	0.07%
Fair value hierarchy Level 3 | Available-for-sale | Corporate debt securities | Discounted cash flow | Weighted average input
Unobservable inputs
Discount rate (as a percent)	4.00%	5.10%
Illiquidity premium (as a percent)	0.27%	0.33%
Comparability adjustment (as a percent)	0.06%	0.00%
Fair value hierarchy Level 3 | Available-for-sale | Commercial mortgage-backed securities
Unobservable inputs
Assets measured at fair value	$ 49.3
Fair value hierarchy Level 3 | Available-for-sale | Commercial mortgage-backed securities | Discounted cash flow | Minimum
Unobservable inputs
Discount rate (as a percent)	3.10%
Probability of default (as a percent)	0.00%
Potential loss severity (as a percent)	0.00%
Fair value hierarchy Level 3 | Available-for-sale | Commercial mortgage-backed securities | Discounted cash flow | Maximum
Unobservable inputs
Discount rate (as a percent)	12.80%
Probability of default (as a percent)	10.00%
Potential loss severity (as a percent)	99.50%
Fair value hierarchy Level 3 | Available-for-sale | Commercial mortgage-backed securities | Discounted cash flow | Weighted average input
Unobservable inputs
Discount rate (as a percent)	10.20%
Probability of default (as a percent)	7.80%
Potential loss severity (as a percent)	39.50%
Fair value hierarchy Level 3 | Available-for-sale | Collateralized debt obligations
Unobservable inputs
Assets measured at fair value	$ 0.2	$ 3.1
Fair value hierarchy Level 3 | Available-for-sale | Collateralized debt obligations | Discounted cash flow
Unobservable inputs
Discount rate (as a percent)	95.10%	28.00%
Probability of default (as a percent)	100.00%	100.00%
Potential loss severity (as a percent)	91.20%	67.00%
Fair value hierarchy Level 3 | Available-for-sale | Collateralized debt obligations | Discounted cash flow | Weighted average input
Unobservable inputs
Discount rate (as a percent)	95.10%	28.00%
Probability of default (as a percent)	100.00%	100.00%
Potential loss severity (as a percent)	91.20%	67.00%
Fair value hierarchy Level 3 | Available-for-sale | Other debt obligations
Unobservable inputs
Assets measured at fair value	$ 6.8	$ 7.5
Fair value hierarchy Level 3 | Available-for-sale | Other debt obligations | Discounted cash flow
Unobservable inputs
Discount rate (as a percent)	5.00%	5.00%
Illiquidity premium (as a percent)	5.00%	7.50%
Fair value hierarchy Level 3 | Available-for-sale | Other debt obligations | Discounted cash flow | Weighted average input
Unobservable inputs
Discount rate (as a percent)	5.00%	5.00%
Illiquidity premium (as a percent)	5.00%	7.50%
Fair value hierarchy Level 3 | Trading | Fixed maturities
Unobservable inputs
Assets measured at fair value	$ 10.5	$ 10.5
Fair value hierarchy Level 3 | Trading | Fixed maturities | Discounted cash flow | Minimum
Unobservable inputs
Discount rate (as a percent)	2.30%	1.10%
Illiquidity premium (as a percent)	0.00%	0.00%
Fair value hierarchy Level 3 | Trading | Fixed maturities | Discounted cash flow | Maximum
Unobservable inputs
Discount rate (as a percent)	9.00%	2.70%
Illiquidity premium (as a percent)	3.00%	3.00%
Fair value hierarchy Level 3 | Trading | Fixed maturities | Discounted cash flow | Weighted average input
Unobservable inputs
Discount rate (as a percent)	2.70%	2.60%
Illiquidity premium (as a percent)	2.40%	2.40%
Fair value hierarchy Level 3 | Other investments
Unobservable inputs
Assets measured at fair value	$ 36.9	$ 35.1
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, equity method real estate investment
Unobservable inputs
Discount rate (as a percent)	7.60%	7.80%
Terminal capitalization rate (as a percent)	6.80%	6.80%
Average market rent growth rate (as a percent)	2.90%	3.20%
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, equity method real estate investment | Weighted average input
Unobservable inputs
Discount rate (as a percent)	7.60%	7.80%
Terminal capitalization rate (as a percent)	6.80%	6.80%
Average market rent growth rate (as a percent)	2.90%	3.20%
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, equity method real estate investment debt
Unobservable inputs
Loan to value (as a percent)	52.50%	52.30%
Credit spread rate (as a percent)	2.10%	2.30%
Fair value hierarchy Level 3 | Other investments | Discounted cash flow, equity method real estate investment debt | Weighted average input
Unobservable inputs
Loan to value (as a percent)	52.50%	52.30%
Credit spread rate (as a percent)	2.10%	2.30%
Fair value hierarchy Level 3 | Separate account assets
Unobservable inputs
Assets measured at fair value	$ 7,225.4	$ 6,881.8
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Minimum
Unobservable inputs
Discount rate (as a percent)	1.40%	1.40%
Illiquidity premium (as a percent)	0.00%	0.00%
Credit spread rate (as a percent)	0.83%	0.81%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Maximum
Unobservable inputs
Discount rate (as a percent)	5.30%	8.20%
Illiquidity premium (as a percent)	0.60%	0.60%
Credit spread rate (as a percent)	4.72%	7.50%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, mortgage loans | Weighted average input
Unobservable inputs
Discount rate (as a percent)	3.70%	3.90%
Illiquidity premium (as a percent)	0.13%	0.07%
Credit spread rate (as a percent)	2.27%	2.41%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Minimum
Unobservable inputs
Discount rate (as a percent)	5.80%	5.30%
Terminal capitalization rate (as a percent)	4.30%	4.30%
Average market rent growth rate (as a percent)	1.80%	2.00%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Maximum
Unobservable inputs
Discount rate (as a percent)	16.20%	16.40%
Terminal capitalization rate (as a percent)	9.30%	9.80%
Average market rent growth rate (as a percent)	4.30%	4.30%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Weighted average input
Unobservable inputs
Discount rate (as a percent)	7.00%	7.20%
Terminal capitalization rate (as a percent)	6.10%	6.20%
Average market rent growth rate (as a percent)	2.90%	3.00%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Minimum
Unobservable inputs
Loan to value (as a percent)	6.30%	7.80%
Credit spread rate (as a percent)	3.30%	1.40%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Maximum
Unobservable inputs
Loan to value (as a percent)	69.70%	63.10%
Credit spread rate (as a percent)	4.60%	4.60%
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Weighted average input
Unobservable inputs
Loan to value (as a percent)	47.00%	47.40%
Credit spread rate (as a percent)	3.90%	2.20%
Fair value hierarchy Level 3 | Investment contracts
Unobservable inputs
Liabilities measured at fair value	$ (176.5)	$ (177.4)
Fair value hierarchy Level 3 | Investment contracts | Discounted cash flow | Minimum
Unobservable inputs
Long duration interest rate (as a percent)	2.60%	2.50%
Long-term equity market volatility (as a percent)	16.00%	14.90%
Non-performance risk (as a percent)	0.30%	0.40%
Lapse rate (as a percent)	0.50%	0.50%
Fair value hierarchy Level 3 | Investment contracts | Discounted cash flow | Maximum
Unobservable inputs
Long duration interest rate (as a percent)	2.70%	2.60%
Long-term equity market volatility (as a percent)	45.90%	44.40%
Non-performance risk (as a percent)	1.70%	1.90%
Lapse rate (as a percent)	14.10%	14.10%

Fair Value Measurements - As123

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Details) - Nonrecurring Fair Value Measurements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage loans | Minimum
Assets and liabilities measured at fair value on a nonrecurring basis
Discount rate (as a percent)			8.80%
Terminal capitalization rate (as a percent)			7.30%
Average market rent growth rate (as a percent)			2.00%
Mortgage loans | Maximum
Assets and liabilities measured at fair value on a nonrecurring basis
Discount rate (as a percent)			11.00%
Terminal capitalization rate (as a percent)			9.00%
Average market rent growth rate (as a percent)			10.90%
Real estate
Assets and liabilities measured at fair value on a nonrecurring basis
Discount rate (as a percent)	10.30%
Terminal capitalization rate (as a percent)	9.00%
Average market rent growth rate (as a percent)	0.00%
Real estate | Minimum
Assets and liabilities measured at fair value on a nonrecurring basis
Discount rate (as a percent)		8.60%	9.60%
Terminal capitalization rate (as a percent)		7.30%	8.30%
Average market rent growth rate (as a percent)		2.70%	3.00%
Real estate | Maximum
Assets and liabilities measured at fair value on a nonrecurring basis
Discount rate (as a percent)		10.50%	11.80%
Terminal capitalization rate (as a percent)		8.50%	8.50%
Average market rent growth rate (as a percent)		3.00%	3.60%
Fair value hierarchy Level 3 | Mortgage loans
Assets and liabilities measured at fair value on a nonrecurring basis
Fair value of assets measured on nonrecurring basis	$ 2.7	$ 9.4	$ 68.9
Fair value hierarchy Level 3 | Mortgage loans | Net realized capital gains (losses)
Assets and liabilities measured at fair value on a nonrecurring basis
Net (gain) loss due to change in fair value of assets measured on nonrecurring basis	2.4	3	10
Fair value hierarchy Level 3 | Real estate
Assets and liabilities measured at fair value on a nonrecurring basis
Fair value of assets measured on nonrecurring basis	13.9	30.9	22.3
Net (gain) loss due to change in fair value of assets measured on nonrecurring basis	5.3
Fair value hierarchy Level 3 | Real estate | Net realized capital gains (losses)
Assets and liabilities measured at fair value on a nonrecurring basis
Net (gain) loss due to change in fair value of assets measured on nonrecurring basis	0.8	2.9	$ 6.2
Fair value hierarchy Level 3 | Real estate | Net investment income
Assets and liabilities measured at fair value on a nonrecurring basis
Net (gain) loss due to change in fair value of assets measured on nonrecurring basis	$ 4.5
Brazil mutual fund company | Fair value hierarchy Level 3 | Intangible assets
Assets and liabilities measured at fair value on a nonrecurring basis
Fair value of assets measured on nonrecurring basis		0
Brazil mutual fund company | Fair value hierarchy Level 3 | Intangible assets | Operating expense
Assets and liabilities measured at fair value on a nonrecurring basis
Net (gain) loss due to change in fair value of assets measured on nonrecurring basis		$ 23

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Option on Consolidated VIEs and Equity Method Investments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)item
Commercial Mortgage Loans of Consolidated VIEs
Fair Value Option, Quantitative Disclosures
Fair value of assets for which fair value option was elected	$ 12.4	$ 18.3
Contractual principal amounts of assets for which the fair value option was elected	12	17.8
Pre-tax gain (loss) due to change in fair value of assets and liabilities for which the fair value option was elected	(0.1)	(2)	$ (1.5)
Credit risk portion of pre-tax gain (loss) due to change in fair value of assets for which the fair value option was elected	$ 0	$ 0	$ 0
Number of loans which are more than 90 days past due or in nonaccrual status | item	0	0	0
Interest income	$ 1.2	$ 3.6	$ 6.2
Obligations of Consolidated VIEs
Fair Value Option, Quantitative Disclosures
Pre-tax gain (loss) due to change in fair value of assets and liabilities for which the fair value option was elected	(9.8)	(2.1)	(0.7)
Fair value of liabilities for which the fair value option was elected	59.9	68.1
Aggregate unpaid principal amounts of obligations for which the fair value option was elected	60	78
Credit risk portion of pre-tax gain (loss) due to change in fair value of liabilities for which the fair value option was elected	(9.8)	(1.9)	(2.4)
Interest expense	1.1	1.1	3
Real Estate Ventures
Fair Value Option, Quantitative Disclosures
Fair value of assets for which fair value option was elected	36.9	35.1
Pre-tax gain (loss) due to change in fair value of assets and liabilities for which the fair value option was elected	1.5	$ 7.2	$ 17.3
Investment Funds
Fair Value Option, Quantitative Disclosures
Fair value of assets for which fair value option was elected	36.9
Pre-tax gain (loss) due to change in fair value of assets and liabilities for which the fair value option was elected	2.8
Dividend income	$ 0.3

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments Not Reported at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Assets (liabilities)
Mortgage loans	$ 13,230.2	$ 12,339.4
Policy loans	823.8	817.1
Short-term debt	(51.4)	(181.1)
Long-term debt	(3,125.7)	(3,265.2)
Carrying amount
Assets (liabilities)
Mortgage loans	13,230.2	12,339.4
Policy loans	823.8	817.1
Other investments	230.3	185
Cash and cash equivalents not required to be reported at fair value	772.5	961.6
Investment contracts	(31,089.4)	(29,063.6)
Short-term debt	(51.4)	(181.1)
Long-term debt	(3,125.7)	(3,265.2)
Separate account liabilities	(127,452.1)	(125,265)
Bank deposits	(2,199.8)	(2,070.8)
Cash collateral payable	(575.7)	(216.3)
Assets (liabilities) measured at fair value
Assets (liabilities)
Mortgage loans	13,453.2	12,653.5
Policy loans	1,011	1,023.1
Other investments	236.8	197.8
Cash and cash equivalents not required to be reported at fair value	772.5	961.6
Investment contracts	(30,622.6)	(28,703.2)
Short-term debt	(51.4)	(181.1)
Long-term debt	(3,242)	(3,411.9)
Separate account liabilities	(126,282)	(124,005.9)
Bank deposits	(2,204.1)	(2,074.4)
Cash collateral payable	(575.7)	(216.3)
Assets (liabilities) measured at fair value | Fair value hierarchy Level 1
Assets (liabilities)
Cash and cash equivalents not required to be reported at fair value	731.4	961.6
Bank deposits	(1,585.1)	(1,457.4)
Cash collateral payable	(575.7)	(216.3)
Assets (liabilities) measured at fair value | Fair value hierarchy Level 2
Assets (liabilities)
Other investments	157.7	118.9
Cash and cash equivalents not required to be reported at fair value	41.1
Investment contracts	(5,400.8)	(4,925)
Short-term debt	(51.4)	(181.1)
Long-term debt	(3,242)	(3,369.1)
Bank deposits	(619)	(617)
Assets (liabilities) measured at fair value | Fair value hierarchy Level 3
Assets (liabilities)
Mortgage loans	13,453.2	12,653.5
Policy loans	1,011	1,023.1
Other investments	79.1	78.9
Investment contracts	(25,221.8)	(23,778.2)
Long-term debt		(42.8)
Separate account liabilities	$ (126,282)	$ (124,005.9)

Statutory Insurance Financia126

Statutory Insurance Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statutory disclosures
Impact of prescribed practices on statutory net income	$ 3.8	$ (2.1)	$ 6.4
Impact of permitted practices on statutory surplus	(180.5)	(158.1)
Statutory reserves assumed by affiliated reinsurance subsidiaries	4,734	3,934.2
Admitted assets under prescribed and permitted statutory accounting practices	1,809	1,447
Statutory net income	996.7	948.6	535.5
Statutory capital and surplus	$ 4,643.8	$ 4,496.7	$ 4,202.1

Segment Information - Reconcili

Segment Information - Reconciliation of Segment Assets to Consolidated (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Segment Information: Assets
Total assets	$ 228,014.3	$ 218,660.3
Retirement and Income Solutions
Segment Information: Assets
Total assets	152,721.7	139,678.5
Principal Global Investors
Segment Information: Assets
Total assets	1,952.1	1,880.4
Principal International
Segment Information: Assets
Total assets	45,118.3	50,588.6
U.S. Insurance Solutions
Segment Information: Assets
Total assets	23,144.2	21,961.4
Corporate
Segment Information: Assets
Total assets	$ 5,078	$ 4,551.4

Segment Information - Reconc128

Segment Information - Reconciliation of Segment Operating Revenues and Earnings to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Revenue And Profit (Loss) From Segments To Consolidated
Net realized capital gains (losses), net of related revenue adjustments									$ 80.9	$ (162.7)	$ (77.4)
Total revenues	$ 3,513.8	$ 2,818	$ 3,025.7	$ 3,036.6	$ 2,807	$ 3,240.9	$ 3,259.2	$ 2,657.3	12,394.1	11,964.4	10,477.6
Pre-tax net realized capital gains (losses), as adjusted									46.3	(170.7)	(143.1)
Income (loss) before income taxes									1,591.7	1,430.8	1,494.9
Impact of court ruling on uncertain tax positions										15.1	(62.2)
Pre-tax gains (losses) associated with exited group medical insurance business that does not qualify for discontinued operations										(3.4)	(0.9)
Principal Global Investors
Operating Revenue And Profit (Loss) From Segments To Consolidated
Inter-segment revenues									235.7	220.6	206.3
Operating Segments
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									12,380.8	12,121.1	10,609.2
Pre-tax operating earnings (losses)									1,668.7	1,637.1	1,723.1
Operating Segments | Retirement and Income Solutions
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									6,150.7	6,166.9	4,799.7
Pre-tax operating earnings (losses)									794.5	740.1	851.2
Inter-segment revenues									373.3	424.5	440.1
Operating Segments | Retirement and Income Solutions | Retirement and Income Solutions - Fee
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									1,743.2	1,774	1,778.9
Operating Segments | Retirement and Income Solutions | Retirement and Income Solutions - Spread
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									4,407.5	4,392.9	3,020.8
Operating Segments | Principal Global Investors
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									1,387.1	1,343.5	1,257.4
Pre-tax operating earnings (losses)									443.8	388.5	350.1
Operating Segments | Principal International
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									1,252	1,220.6	1,329.8
Pre-tax operating earnings (losses)									288.1	271.3	352.7
Operating Segments | U.S. Insurance Solutions
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									3,637.3	3,440.6	3,262.6
Pre-tax operating earnings (losses)									361.2	429.5	344.1
Operating Segments | U.S. Insurance Solutions | Specialty benefits insurance
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									2,011.4	1,868.1	1,727.1
Operating Segments | U.S. Insurance Solutions | Individual life insurance
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									1,626.1	1,572.7	1,535.7
Operating Segments | U.S. Insurance Solutions | U.S. Insurance Solutions Eliminations
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									(0.2)	(0.2)	(0.2)
Operating Segments | Corporate
Operating Revenue And Profit (Loss) From Segments To Consolidated
Operating revenues									(46.3)	(50.5)	(40.3)
Pre-tax operating earnings (losses)									(218.9)	(192.3)	(175)
Reconciling Items
Operating Revenue And Profit (Loss) From Segments To Consolidated
Net realized capital gains (losses), net of related revenue adjustments									80.9	(162.7)	(77.4)
Certain revenue adjustments related to equity method investments									(67.6)	(55.5)	(54.4)
Other income on a tax indemnification										60.2
Exited group medical insurance business										1.3	0.2
Pre-tax net realized capital gains (losses), as adjusted									46.3	(170.7)	(143.1)
Pre-tax other adjustments									(86.4)	11.7	(63.1)
Certain earnings adjustments related to equity method investments and noncontrolling interest									$ (36.9)	$ (47.3)	$ (22)

Segment Information - Net Reali

Segment Information - Net Realized Capital Gains (Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Information: Net realized capital gains (losses), as adjusted
Net realized capital gains (losses)	$ 171.1	$ (51.1)	$ 14.7
Certain derivative and hedging-related adjustments	(94.1)	(111.7)	(92.8)
Certain market value adjustments to fee revenues	(2.5)	(1.1)
Certain adjustments related to equity method investments	0.1
Certain adjustments related to sponsored investment funds	6.1	1.3
Recognition of front-end fee revenue	0.2	(0.1)	0.7
Net realized capital gains (losses), net of related revenue adjustments	80.9	(162.7)	(77.4)
Amortization of deferred acquisition costs and other actuarial balances	(77.4)	(14)	(49.3)
Capital (gains) losses distributed	(7.2)	6.2	(21.2)
Certain market value adjustments of embedded derivatives	50	(0.2)	4.8
Pre-tax net realized capital gains (losses), as adjusted	$ 46.3	$ (170.7)	$ (143.1)

Segment Information - Income Ta

Segment Information - Income Tax Expense by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Information: Income tax expense (benefit)
Income taxes (benefits)	$ 229.9	$ 177.6	$ 318.5
Operating Segments
Segment Information: Income tax expense (benefit)
Total segment income tax expense (benefit) from operating earnings (losses)	337.6	341.9	372.2
Operating Segments | Retirement and Income Solutions
Segment Information: Income tax expense (benefit)
Total segment income tax expense (benefit) from operating earnings (losses)	98.6	76.1	128.5
Operating Segments | Principal Global Investors
Segment Information: Income tax expense (benefit)
Total segment income tax expense (benefit) from operating earnings (losses)	166.8	148.4	132.9
Operating Segments | Principal International
Segment Information: Income tax expense (benefit)
Total segment income tax expense (benefit) from operating earnings (losses)	62.7	51.5	84.7
Operating Segments | U.S. Insurance Solutions
Segment Information: Income tax expense (benefit)
Total segment income tax expense (benefit) from operating earnings (losses)	118.8	143.1	112.8
Operating Segments | Corporate
Segment Information: Income tax expense (benefit)
Total segment income tax expense (benefit) from operating earnings (losses)	(109.3)	(77.2)	(86.7)
Reconciling Items
Segment Information: Income tax expense (benefit)
Tax expense/benefit related to net realized capital gains (losses), as adjusted	(6.6)	(45.6)	(43.6)
Tax expense (benefit) related to other after-tax adjustments	(34.4)	(63.2)	44.3
Tax expense (benefit) associated with certain adjustments related to equity method investments and noncontrolling interest	$ (66.7)	$ (55.5)	$ (54.4)

Segment Information - Depreciat

Segment Information - Depreciation and Amortization Expense by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Information: Depreciation and amortization expense
Depreciation and amortization expense	$ 133.5	$ 143.7	$ 122.7
Operating Segments | Retirement and Income Solutions
Segment Information: Depreciation and amortization expense
Total segment depreciation and amortization expense	30.4	28.3	27.5
Operating Segments | Principal Global Investors
Segment Information: Depreciation and amortization expense
Total segment depreciation and amortization expense	18.8	16.5	17.1
Operating Segments | Principal International
Segment Information: Depreciation and amortization expense
Total segment depreciation and amortization expense	50.1	69.3	51.6
Operating Segments | U.S. Insurance Solutions
Segment Information: Depreciation and amortization expense
Total segment depreciation and amortization expense	26.8	23.1	21.2
Operating Segments | Corporate
Segment Information: Depreciation and amortization expense
Total segment depreciation and amortization expense	$ 7.4	$ 6.5	$ 5.3

Stock-Based Compensation Pla132

Stock-Based Compensation Plans - Stock-Based Awards (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended			132 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	May 20, 2014
Stock-Based Compensation Plans
Stock-Based Compensation Plans - Disclosures
Compensation cost	$ 73.8	$ 69.7	$ 66.2
Related income tax benefit	21.5	22.5	21.6
Capitalized as part of an asset	$ 2.8	$ 2.2	$ 2.5
2014 Stock Incentive Plan and 2014 Directors Stock Plan
Stock-Based Compensation Plans - Disclosures
Maximum number of new shares of common stock available for grant (in shares)	9.9			9.9
Stock Incentive Plan, Directors Stock Plan and Long-Term Performance Plan
Stock-Based Compensation Plans - Disclosures
Options granted (in shares)				0
Awards or units granted (in shares)				0
Amended and Restated 2010 Stock Incentive Plan and 2005 Directors Stock Plan
Stock-Based Compensation Plans - Disclosures
Number of shares that will be granted					0

Stock-Based Compensation Pla133

Stock-Based Compensation Plans - Nonqualified Stock Options (Details) - Nonqualified Stock Options - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in options outstanding
Options outstanding at beginning of period (in shares)	7.7
Options granted (in shares)	1.1
Options exercised (in shares)	0.7
Options expired (in shares)	0.6
Options outstanding at end of period (in shares)	7.5	7.7
Options vested or expected to vest at end of period (in shares)	7.4
Options exercisable at end of period (in shares)	5.9
Options outstanding at beginning of period weighted-average exercise price (in dollars per share)	$ 43.71
Options granted weighted-average exercise price (in dollars per share)	37.38
Options exercised weighted-average exercise price (in dollars per share)	20.52
Options expired weighted-average exercise price (in dollars per share)	49.31
Options outstanding at end of period weighted-average exercise price (in dollars per share)	44.61	$ 43.71
Options vested or expected to vest at end of period weighted-average exercise price (in dollars per share)	44.62
Options exercisable at end of period weighted-average exercise price (in dollars per share)	$ 45.64
Options outstanding at end of period intrinsic value	$ 108.9
Options vested or expected to vest at end of period intrinsic value	108.6
Options exercisable at end of period intrinsic value	82.6
Total intrinsic value of options exercised	$ 25.7	$ 17.4	$ 25.4
Assumptions used to estimate fair value of stock options granted during period
Weighted-average expected volatility (as a percent)	31.70%	52.20%	53.20%
Weighted-average expected term	6 years 6 months	6 years 6 months	6 years 6 months
Weighted-average risk-free interest rate (as a percent)	1.50%	1.80%	2.00%
Weighted-average expected dividend yield (as a percent)	4.07%	2.81%	2.50%
Weighted-average estimated fair value of stock options granted (in dollars per share)	$ 8.91	$ 20.43	$ 18.89
Other nonqualified stock option disclosures
Unrecognized compensation costs	$ 2.9
Weighted-average service period over which unrecognized compensation costs will be recognized	1 year 8 months 12 days
Cash received from stock options exercised	$ 15.3	$ 52.7	$ 56.1
Tax benefits realized for the tax deductions from options exercised	$ 9	$ 6	$ 8.6
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Weighted-average remaining contractual life for stock options exercisable	3 years
Range of exercise prices, Range 1
Change in options outstanding
Options outstanding at end of period (in shares)	0.4
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Lower limit of exercise price range (in dollars per share)	$ 11.07
Upper limit of exercise price range (in dollars per share)	$ 21.69
Weighted-average remaining contractual life	2 years 2 months 12 days
Range of exercise prices, Range 2
Change in options outstanding
Options outstanding at end of period (in shares)	1.5
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Lower limit of exercise price range (in dollars per share)	$ 21.70
Upper limit of exercise price range (in dollars per share)	$ 32.32
Weighted-average remaining contractual life	5 years 2 months 12 days
Range of exercise prices, Range 3
Change in options outstanding
Options outstanding at end of period (in shares)	1.5
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Lower limit of exercise price range (in dollars per share)	$ 32.33
Upper limit of exercise price range (in dollars per share)	$ 42.95
Weighted-average remaining contractual life	8 years
Range of exercise prices, Range 4
Change in options outstanding
Options outstanding at end of period (in shares)	1.2
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Lower limit of exercise price range (in dollars per share)	$ 42.96
Upper limit of exercise price range (in dollars per share)	$ 53.58
Weighted-average remaining contractual life	7 years 8 months 12 days
Range of exercise prices, Range 5
Change in options outstanding
Options outstanding at end of period (in shares)	2.9
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Lower limit of exercise price range (in dollars per share)	$ 53.59
Upper limit of exercise price range (in dollars per share)	$ 64.22
Weighted-average remaining contractual life	8 months 12 days
Range of exercise prices, Total Range
Change in options outstanding
Options outstanding at end of period (in shares)	7.5
Summary of weighted-average remaining contractual lives for stock options outstanding and range of exercise prices
Lower limit of exercise price range (in dollars per share)	$ 11.07
Upper limit of exercise price range (in dollars per share)	$ 64.22
Weighted-average remaining contractual life	4 years 2 months 12 days
2014 Stock Incentive Plan, Amended and Restated 2010 Stock Incentive Plan and Stock Incentive Plan
Stock-Based Compensation Plans - Disclosures
Option expiration period	10 years
Vesting period	3 years
Change in options outstanding
Options granted (in shares)	1.1	0.6	0.6

Stock-Based Compensation Pla134

Stock-Based Compensation Plans - Performance Share Awards and Restricted Stock Units (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Performance Share Awards
Change in nonvested units outstanding
Awards or units outstanding at beginning of period (in shares)	0.9
Awards or units granted (in shares)	0.3	0.3	0.3
Awards or units vested (in shares)	0.3
Awards or units outstanding at end of period (in shares)	0.9	0.9
Awards or units outstanding at beginning of period weighted-average grant-date fair value (in dollars per share)	$ 41.57
Awards or units granted weighted-average grant-date fair value (in dollars per share)	37.38	$ 51.33	$ 44.88
Awards or units vested weighted-average grant-date fair value (in dollars per share)	30.70
Awards or units outstanding at end of period weighted-average grant-date fair value (in dollars per share)	$ 44.23	$ 41.57
Other award and unit disclosures
Lower limit multiple of initial target awards (as a percent)	0.00%
Upper limit multiple of initial target awards (as a percent)	150.00%
Unrecognized compensation costs	$ 4.5
Weighted-average service period over which unrecognized compensation costs will be recognized	1 year 6 months
Tax benefits realized for the tax deductions from awards or units paid out	$ 4.8	$ 7.4	$ 4
Intrinsic value from awards or units vested	$ 18.1	$ 20.1	$ 11.4
Performance period for goals	3 years
Restricted Stock Units
Change in nonvested units outstanding
Awards or units outstanding at beginning of period (in shares)	3
Awards or units granted (in shares)	1.3	0.9	0.9
Awards or units vested (in shares)	1.3
Awards or units outstanding at end of period (in shares)	3	3
Awards or units outstanding at beginning of period weighted-average grant-date fair value (in dollars per share)	$ 41.32
Awards or units granted weighted-average grant-date fair value (in dollars per share)	37.59	$ 51.35	$ 45.03
Awards or units vested weighted-average grant-date fair value (in dollars per share)	31.23
Awards or units outstanding at end of period weighted-average grant-date fair value (in dollars per share)	$ 43.77	$ 41.32
Other award and unit disclosures
Unrecognized compensation costs	$ 45
Weighted-average service period over which unrecognized compensation costs will be recognized	1 year 8 months 12 days
Tax benefits realized for the tax deductions from awards or units paid out	$ 16.1	$ 18.8	$ 12.8
Intrinsic value from awards or units vested	$ 46.2	$ 53.6	$ 38.5
2014 Stock Incentive Plan, Amended and Restated 2010 Stock Incentive Plan and Stock Incentive Plan | Restricted Stock Units
Other award and unit disclosures
Vesting period	3 years
2014 Directors Stock Plan and 2005 Directors Stock Plan | Restricted Stock Units
Other award and unit disclosures
Vesting period	1 year
Employee Stock Purchase Plan
Stock-Based Compensation Plans - Disclosures
Share purchases under employee stock purchase plan (in shares)	0.7	0.6	0.5
Weighted-average fair value of discount on employee stock purchase plan (in dollars per share)	$ 14	$ 7.29	$ 8.94
Shares available to be issued under employee stock purchase plan (in shares)	3.4

Stock-Based Compensation Pla135

Stock-Based Compensation Plans - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan - USD ($) $ / shares in Units, shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-Based Compensation Plans - Disclosures
Maximum value of company common stock that can be purchased by an employee per year	$ 25,000
Employee purchase price as a percent of fair market value (as a percent)	85.00%
Share purchases under employee stock purchase plan (in shares)	0.7	0.6	0.5
Weighted-average fair value of discount on employee stock purchase plan (in dollars per share)	$ 14	$ 7.29	$ 8.94
Intrinsic value from shares settled	$ 10,200,000	$ 4,100,000	$ 4,700,000
Cash received from shares issued	25,500,000	23,400,000	22,200,000
Tax benefits realized from the settlement of share-based payment arrangements	$ 600,000	$ 600,000	$ 1,100,000
Shares available to be issued under employee stock purchase plan (in shares)	3.4

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Common Share
Net income (loss)	$ 338.2	$ 327.4	$ 327	$ 369.2	$ 258.3	$ 300.9	$ 264.9	$ 429.1	$ 1,361.8	$ 1,253.2	$ 1,176.4
Subtract:
Net income (loss) attributable to noncontrolling interest									45.3	19.2	32.3
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Adjustments to redemption amounts of redeemable noncontrolling interests											19.7
Total									$ 1,316.5	$ 1,209.3	$ 1,091.4
Weighted-average shares outstanding
Basic									289.4	294.4	294.7
Dilutive effects:
Stock options									1.3	1.5	1.8
Restricted stock units									1.7	1.7	1.8
Performance share awards									0.3	0.4	0.4
Diluted									292.7	298	298.7
Net income (loss) per common share:
Basic	$ 1.10	$ 1.07	$ 1.11	$ 1.26	$ 0.87	$ 1.02	$ 0.82	$ 1.41	$ 4.55	$ 4.11	$ 3.70
Diluted	$ 1.09	$ 1.06	$ 1.10	$ 1.25	$ 0.86	$ 1.01	$ 0.81	$ 1.39	$ 4.50	$ 4.06	$ 3.65

Quarterly Results of Operati137

Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Results of Operations (Unaudited)
Total revenues	$ 3,513.8	$ 2,818	$ 3,025.7	$ 3,036.6	$ 2,807	$ 3,240.9	$ 3,259.2	$ 2,657.3	$ 12,394.1	$ 11,964.4	$ 10,477.6
Total expenses	3,132.5	2,447.3	2,625.8	2,596.8	2,498	2,871.7	2,964.7	2,199.2	10,802.4	10,533.6	8,982.7
Net income (loss)	338.2	327.4	327	369.2	258.3	300.9	264.9	429.1	1,361.8	1,253.2	1,176.4
Net income (loss) available to common stockholders	$ 318	$ 308.2	$ 322.3	$ 368	$ 253.6	$ 300.4	$ 241.1	$ 414.2	$ 1,316.5	$ 1,209.3	$ 1,111.1
Basic earnings per common share (in dollars per share)	$ 1.10	$ 1.07	$ 1.11	$ 1.26	$ 0.87	$ 1.02	$ 0.82	$ 1.41	$ 4.55	$ 4.11	$ 3.70
Diluted earnings per common share (in dollars per share)	$ 1.09	$ 1.06	$ 1.10	$ 1.25	$ 0.86	$ 1.01	$ 0.81	$ 1.39	$ 4.50	$ 4.06	$ 3.65

Condensed Consolidating Fina138

Condensed Consolidating Financial Information - Guarantor, Statements of Financial Position (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Fixed maturities, available-for-sale	$ 54,846.1	$ 49,966.5
Fixed maturities, trading	398.4	686.8
Equity securities, available-for-sale	98.9	104.5
Equity securities, trading	1,413.4	1,202.7
Mortgage loans	13,230.2	12,339.4
Real estate	1,368.8	1,451.8
Policy loans	823.8	817.1
Investment in unconsolidated entities	773.2	632.7
Other investments	2,882.7	2,619
Cash and cash equivalents	2,719.6	2,564.8	$ 1,863.9	$ 2,371.8
Accrued investment income	580.6	545.6
Premiums due and other receivables	1,361.9	1,429.3
Deferred acquisition costs	3,380.2	3,276.1	2,993	3,077
Property and equipment	699	633.8
Goodwill	1,020.8	1,009	1,007.4
Other intangibles	1,325.3	1,359.2
Separate account assets	139,832.6	136,978.9
Other assets	1,258.8	1,043.1
Total assets	228,014.3	218,660.3
Liabilities
Contractholder funds	37,953.6	35,716.1
Future policy benefits and claims	29,000.7	25,856.5
Other policyholder funds	890.4	805.4
Short-term debt	51.4	181.1
Long-term debt	3,125.7	3,265.2
Income taxes currently payable	12.9	18.4
Deferred income taxes	972.4	697.2
Separate account liabilities	139,832.6	136,978.9
Other liabilities	5,783.3	5,678.4
Total liabilities	217,623	209,197.2
Redeemable noncontrolling interest	97.5	85.7	58	247.2
Stockholders' equity
Common stock	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Noncontrolling interest	66.5	65.8
Total stockholders' equity	10,293.8	9,377.4	10,232	9,777
Total liabilities and stockholders' equity	228,014.3	218,660.3
Principal Financial Group, Inc. Parent Only
Assets
Investment in unconsolidated entities	12,597.9	12,223.4
Other investments	9.8	9.7
Cash and cash equivalents	882.6	578.7	412.4	131.5
Other assets	573.7	458
Total assets	14,064	13,269.8
Liabilities
Long-term debt	3,126.4	3,223.8
Other liabilities	710.3	734.4
Total liabilities	3,836.7	3,958.2
Stockholders' equity
Common stock	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Total stockholders' equity	10,227.3	9,311.6
Total liabilities and stockholders' equity	14,064	13,269.8
Principal Life Insurance Company Only
Assets
Fixed maturities, available-for-sale	48,672.1	43,862.7
Fixed maturities, trading	135.6	436.2
Equity securities, available-for-sale	96.3	101.7
Equity securities, trading	8.2	0.3
Mortgage loans	12,460.7	11,696.9
Real estate	4.4	6.3
Policy loans	784.8	786.3
Investment in unconsolidated entities	2,071.1	2,220.5
Other investments	4,740	3,944.3
Cash and cash equivalents	675.1	1,127.9	602.7	1,332.2
Accrued investment income	513.7	477.9
Premiums due and other receivables	1,538	1,512.7
Deferred acquisition costs	3,184.2	3,057.3
Property and equipment	610.4	552
Goodwill	54.3	54.3
Other intangibles	23.5	24.6
Separate account assets	103,661.9	94,762.8
Other assets	969.5	878
Total assets	180,203.8	165,502.7
Liabilities
Contractholder funds	35,337.7	33,151.7
Future policy benefits and claims	24,392.6	21,914
Other policyholder funds	780.7	718.1
Deferred income taxes	533.6	415.2
Separate account liabilities	103,661.9	94,762.8
Other liabilities	7,300.9	6,330.1
Total liabilities	172,007.4	157,291.9
Stockholders' equity
Common stock	2.5	2.5
Additional paid-in capital	5,305.6	5,334.4
Retained earnings (accumulated deficit)	2,139.9	2,232.6
Accumulated other comprehensive income (loss)	748.4	641.3
Total stockholders' equity attributable to Principal Financial Group, Inc.	8,196.4	8,210.8
Total stockholders' equity	8,196.4	8,210.8
Total liabilities and stockholders' equity	180,203.8	165,502.7
Principal Financial Services, Inc. and Other Subsidiaries Combined
Assets
Fixed maturities, available-for-sale	6,559.9	6,482.5
Fixed maturities, trading	262.8	250.6
Equity securities, available-for-sale	2.6	2.8
Equity securities, trading	1,405.2	1,202.4
Mortgage loans	1,289.4	1,155.3
Real estate	1,364.4	1,445.5
Policy loans	39	30.8
Investment in unconsolidated entities	6,493.7	6,229.8
Other investments	1,783	1,636.5
Cash and cash equivalents	2,082.8	1,253.7	1,253.6	894.5
Accrued investment income	74.5	76.7
Premiums due and other receivables	2,836	2,465.9
Deferred acquisition costs	196	218.8
Property and equipment	88.6	81.8
Goodwill	966.5	954.7
Other intangibles	1,301.8	1,334.6
Separate account assets	36,170.7	42,216.1
Other assets	3,507.7	2,995.6
Total assets	66,424.6	70,034.1
Liabilities
Contractholder funds	2,949.2	2,885.1
Future policy benefits and claims	5,312.1	4,479.3
Other policyholder funds	111	88.2
Short-term debt	51.4	181.1
Long-term debt	495.1	535.2
Income taxes currently payable	124.3	101.9
Deferred income taxes	1,111.9	928.9
Separate account liabilities	36,170.7	42,216.1
Other liabilities	7,425.9	6,323.6
Total liabilities	53,751.6	57,739.4
Redeemable noncontrolling interest	97.5	85.7
Stockholders' equity
Additional paid-in capital	9,010.9	9,000
Retained earnings (accumulated deficit)	3,724.3	3,522.3
Accumulated other comprehensive income (loss)	(230.9)	(383.6)
Total stockholders' equity attributable to Principal Financial Group, Inc.	12,504.3	12,138.7
Noncontrolling interest	71.2	70.3
Total stockholders' equity	12,575.5	12,209
Total liabilities and stockholders' equity	66,424.6	70,034.1
Eliminations, Notes Guarantor
Assets
Fixed maturities, available-for-sale	(385.9)	(378.7)
Mortgage loans	(519.9)	(512.8)
Investment in unconsolidated entities	(20,389.5)	(20,041)
Other investments	(3,650.1)	(2,971.5)
Cash and cash equivalents	(920.9)	(395.5)	$ (404.8)	$ 13.6
Accrued investment income	(7.6)	(9)
Premiums due and other receivables	(3,012.1)	(2,549.3)
Other assets	(3,792.1)	(3,288.5)
Total assets	(32,678.1)	(30,146.3)
Liabilities
Contractholder funds	(333.3)	(320.7)
Future policy benefits and claims	(704)	(536.8)
Other policyholder funds	(1.3)	(0.9)
Long-term debt	(495.8)	(493.8)
Income taxes currently payable	(111.4)	(83.5)
Deferred income taxes	(673.1)	(646.9)
Other liabilities	(9,653.8)	(7,709.7)
Total liabilities	(11,972.7)	(9,792.3)
Stockholders' equity
Common stock	(2.5)	(2.5)
Additional paid-in capital	(14,316.5)	(14,334.4)
Retained earnings (accumulated deficit)	(5,864.2)	(5,754.9)
Accumulated other comprehensive income (loss)	(517.5)	(257.7)
Total stockholders' equity attributable to Principal Financial Group, Inc.	(20,700.7)	(20,349.5)
Noncontrolling interest	(4.7)	(4.5)
Total stockholders' equity	(20,705.4)	(20,354)
Total liabilities and stockholders' equity	$ (32,678.1)	$ (30,146.3)

Condensed Consolidating Fina139

Condensed Consolidating Financial Information - Guarantor, Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Premiums and other considerations									$ 5,299.1	$ 5,310.3	$ 3,722.9
Fees and other revenues									3,627.4	3,653.1	3,482.1
Net investment income (loss)									3,296.5	3,052.1	3,257.9
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									269.5	(20.9)	92.7
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities									(98.8)	(0.8)	23.8
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income									0.4	(29.4)	(101.8)
Net impairment (losses) recoveries on available-for-sale securities									(98.4)	(30.2)	(78)
Net realized capital gains (losses)									171.1	(51.1)	14.7
Total revenues	$ 3,513.8	$ 2,818	$ 3,025.7	$ 3,036.6	$ 2,807	$ 3,240.9	$ 3,259.2	$ 2,657.3	12,394.1	11,964.4	10,477.6
Expenses
Benefits, claims and settlement expenses									6,913.2	6,697.7	5,231
Dividends to policyholders									156.6	163.5	177.4
Operating expenses									3,732.6	3,672.4	3,574.3
Total expenses	3,132.5	2,447.3	2,625.8	2,596.8	2,498	2,871.7	2,964.7	2,199.2	10,802.4	10,533.6	8,982.7
Income (loss) before income taxes									1,591.7	1,430.8	1,494.9
Income taxes (benefits)									229.9	177.6	318.5
Net income (loss)	338.2	327.4	327	369.2	258.3	300.9	264.9	429.1	1,361.8	1,253.2	1,176.4
Net income (loss) attributable to noncontrolling interest									45.3	19.2	32.3
Net income (loss) attributable to Principal Financial Group, Inc.									1,316.5	1,234	1,144.1
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Net income (loss) available to common stockholders	318	308.2	322.3	368	253.6	300.4	241.1	414.2	1,316.5	1,209.3	1,111.1
Net income (loss)	$ 338.2	$ 327.4	$ 327	$ 369.2	$ 258.3	$ 300.9	$ 264.9	$ 429.1	1,361.8	1,253.2	1,176.4
Other comprehensive income (loss)									221	(943.1)	(144.1)
Comprehensive income (loss)									1,582.8	310.1	1,032.3
Principal Financial Group, Inc. Parent Only
Revenues
Net investment income (loss)									3.4	1.6	0.5
Total revenues									3.4	1.6	0.5
Expenses
Operating expenses									312.3	175.4	144.3
Total expenses									312.3	175.4	144.3
Income (loss) before income taxes									(308.9)	(173.8)	(143.8)
Income taxes (benefits)									(134.9)	(71.2)	(86.3)
Equity in the net income (loss) of subsidiaries									1,490.5	1,336.6	1,201.6
Net income (loss)									1,316.5	1,234	1,144.1
Net income (loss) attributable to Principal Financial Group, Inc.									1,316.5	1,234	1,144.1
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Net income (loss) available to common stockholders										1,209.3	1,111.1
Net income (loss)									1,316.5	1,234	1,144.1
Other comprehensive income (loss)									218.8	(988)	(198.8)
Comprehensive income (loss)									1,535.3	246	945.3
Principal Life Insurance Company Only
Revenues
Premiums and other considerations									4,869	4,950	3,329.2
Fees and other revenues									1,956.1	2,014.1	1,892.5
Net investment income (loss)									2,300.2	2,164	2,288.3
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									210.4	357.2	1,117.6
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities									(92.2)	(0.4)	33
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income									(3)	(29.4)	(102.1)
Net impairment (losses) recoveries on available-for-sale securities									(95.2)	(29.8)	(69.1)
Net realized capital gains (losses)									115.2	327.4	1,048.5
Total revenues									9,240.5	9,455.5	8,558.5
Expenses
Benefits, claims and settlement expenses									6,177.9	6,047.1	4,521.2
Dividends to policyholders									156.6	163.5	177.4
Operating expenses									2,113.9	2,189.2	2,168.8
Total expenses									8,448.4	8,399.8	6,867.4
Income (loss) before income taxes									792.1	1,055.7	1,691.1
Income taxes (benefits)									97.9	235.7	426.8
Equity in the net income (loss) of subsidiaries									395.9	114.6	(306.8)
Net income (loss)									1,090.1	934.6	957.5
Net income (loss) attributable to Principal Financial Group, Inc.									1,090.1	934.6	957.5
Net income (loss) available to common stockholders										934.6	957.5
Net income (loss)									1,090.1	934.6	957.5
Other comprehensive income (loss)									116.5	(446.9)	367.7
Comprehensive income (loss)									1,206.6	487.7	1,325.2
Principal Financial Services, Inc. and Other Subsidiaries Combined
Revenues
Premiums and other considerations									430.1	360.3	393.7
Fees and other revenues									2,061.1	2,037.1	1,981.3
Net investment income (loss)									2,004.7	1,632.5	1,738.2
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									48.1	(378.1)	(1,024.9)
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities									(6.6)	(0.4)	(9.2)
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income									3.4		0.3
Net impairment (losses) recoveries on available-for-sale securities									(3.2)	(0.4)	(8.9)
Net realized capital gains (losses)									44.9	(378.5)	(1,033.8)
Total revenues									4,540.8	3,651.4	3,079.4
Expenses
Benefits, claims and settlement expenses									746.3	661.9	721.3
Operating expenses									1,629.7	1,643.3	1,589.3
Total expenses									2,376	2,305.2	2,310.6
Income (loss) before income taxes									2,164.8	1,346.2	768.8
Income taxes (benefits)									270	14.7	(19.8)
Equity in the net income (loss) of subsidiaries									(366)	17.4	449.6
Net income (loss)									1,528.8	1,348.9	1,238.2
Net income (loss) attributable to noncontrolling interest									45.3	19.2	32.3
Net income (loss) attributable to Principal Financial Group, Inc.									1,483.5	1,329.7	1,205.9
Net income (loss) available to common stockholders										1,329.7	1,205.9
Net income (loss)									1,528.8	1,348.9	1,238.2
Other comprehensive income (loss)									218.1	(935)	180.3
Comprehensive income (loss)									1,746.9	413.9	1,418.5
Eliminations, Notes Guarantor
Revenues
Fees and other revenues									(389.8)	(398.1)	(391.7)
Net investment income (loss)									(1,011.8)	(746)	(769.1)
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									11
Net realized capital gains (losses)									11
Total revenues									(1,390.6)	(1,144.1)	(1,160.8)
Expenses
Benefits, claims and settlement expenses									(11)	(11.3)	(11.5)
Operating expenses									(323.3)	(335.5)	(328.1)
Total expenses									(334.3)	(346.8)	(339.6)
Income (loss) before income taxes									(1,056.3)	(797.3)	(821.2)
Income taxes (benefits)									(3.1)	(1.6)	(2.2)
Equity in the net income (loss) of subsidiaries									(1,520.4)	(1,468.6)	(1,344.4)
Net income (loss)									(2,573.6)	(2,264.3)	(2,163.4)
Net income (loss) attributable to Principal Financial Group, Inc.									(2,573.6)	(2,264.3)	(2,163.4)
Net income (loss) available to common stockholders										(2,264.3)	(2,163.4)
Net income (loss)									(2,573.6)	(2,264.3)	(2,163.4)
Other comprehensive income (loss)									(332.4)	1,426.8	(493.3)
Comprehensive income (loss)									$ (2,906)	$ (837.5)	$ (2,656.7)

Condensed Consolidating Fina140

Condensed Consolidating Financial Information - Guarantor, Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net cash provided by (used in) operating activities	$ 3,857.8	$ 4,377.1	$ 3,102.9
Investing activities
Available-for-sale securities: Purchases	(13,763.8)	(9,920.3)	(9,054)
Available-for-sale securities: Sales	1,890.5	1,563	2,512
Available-for-sale securities: Maturities	7,742.8	6,625.9	6,244.7
Mortgage loans acquired or originated	(2,889)	(2,275.1)	(2,169.6)
Mortgage loans sold or repaid	2,068.7	1,687.3	1,793.6
Real estate acquired	(109.7)	(322)	(281.7)
Net (purchases) sales of property and equipment	(154.9)	(136.4)	(136)
Purchase of interests in subsidiaries, net of cash acquired		(291.2)
Net change in other investments	61.5	(98.8)	(81.7)
Net cash provided by (used in) investing activities	(5,153.9)	(3,167.6)	(1,172.7)
Financing activities
Issuance of common stock	37.8	76.1	77.5
Acquisition of treasury stock	(277.3)	(300.6)	(222.7)
Proceeds from financing element derivatives	0.4	0.3	15.1
Payments for financing element derivatives	(87.7)	(82)	(58)
Excess tax benefits from share-based payment arrangements	12	15.7	9.7
Purchase of subsidiary shares from noncontrolling interest	(2.4)	(22.5)	(227)
Dividends to common stockholders	(464.9)	(441)	(376.6)
Dividends to preferred stockholders		(16.5)	(33)
Preferred stock redemption		(550)
Issuance of long-term debt	656.1	804.9	38.5
Principal repayments of long-term debt	(799.3)	(52.6)	(100.3)
Net proceeds from (repayments of) short-term borrowings	(131.4)	157	(118.3)
Investment contract deposits	10,770.9	6,492.3	5,638.4
Investment contract withdrawals	(8,392.7)	(6,666.8)	(7,099.2)
Net increase (decrease) in banking operation deposits	129	91.1	30.7
Other	0.4	(14)	(12.9)
Net cash provided by (used in) financing activities	1,450.9	(508.6)	(2,438.1)
Net increase (decrease) in cash and cash equivalents	154.8	700.9	(507.9)
Cash and cash equivalents at beginning of period	2,564.8	1,863.9	2,371.8
Cash and cash equivalents at end of period	2,719.6	2,564.8	1,863.9
Principal Financial Group, Inc. Parent Only
Operating activities
Net cash provided by (used in) operating activities	(188.6)	(85.1)	(81.6)
Investing activities
Net (purchases) sales of property and equipment	(0.1)
Dividends and returns of capital received from (contributed to) unconsolidated entities	1,295.3	685.5	917.7
Net change in other investments	1.3	5.4	(0.7)
Net cash provided by (used in) investing activities	1,296.5	690.9	917
Financing activities
Issuance of common stock	37.8	76.1	77.5
Acquisition of treasury stock	(277.3)	(300.6)	(222.7)
Excess tax benefits from share-based payment arrangements	0.7	0.7	0.3
Dividends to common stockholders	(464.9)	(441)	(376.6)
Dividends to preferred stockholders		(16.5)	(33)
Preferred stock redemption		(550)
Issuance of long-term debt	644.2	791.8
Principal repayments of long-term debt	(744.5)
Net cash provided by (used in) financing activities	(804)	(439.5)	(554.5)
Net increase (decrease) in cash and cash equivalents	303.9	166.3	280.9
Cash and cash equivalents at beginning of period	578.7	412.4	131.5
Cash and cash equivalents at end of period	882.6	578.7	412.4
Principal Life Insurance Company Only
Operating activities
Net cash provided by (used in) operating activities	3,657.5	3,803	2,461
Investing activities
Available-for-sale securities: Purchases	(12,771.1)	(8,835.2)	(8,038.3)
Available-for-sale securities: Sales	1,312.7	1,017.2	2,066.1
Available-for-sale securities: Maturities	7,097.4	5,847.9	5,696.6
Mortgage loans acquired or originated	(2,615.7)	(2,177.1)	(2,141)
Mortgage loans sold or repaid	1,843.6	1,441.8	1,658.3
Real estate acquired		(0.3)	(0.8)
Net (purchases) sales of property and equipment	(113.2)	(109.3)	(115.1)
Dividends and returns of capital received from (contributed to) unconsolidated entities	3.1	(1.5)	255.2
Net change in other investments	317.7	555	175.7
Net cash provided by (used in) investing activities	(4,925.5)	(2,261.5)	(443.3)
Financing activities
Proceeds from financing element derivatives	0.4	0.3	15.1
Payments for financing element derivatives	(87.7)	(82)	(58)
Excess tax benefits from share-based payment arrangements	4.7	5.7	4.2
Principal repayments of long-term debt			(100)
Capital received from (dividends and capital paid to) parent	(1,195)	(485.6)	(867.7)
Investment contract deposits	10,465.8	6,214.8	5,349.1
Investment contract withdrawals	(8,373.3)	(6,655.5)	(7,088.8)
Other	0.3	(14)	(1.1)
Net cash provided by (used in) financing activities	815.2	(1,016.3)	(2,747.2)
Net increase (decrease) in cash and cash equivalents	(452.8)	525.2	(729.5)
Cash and cash equivalents at beginning of period	1,127.9	602.7	1,332.2
Cash and cash equivalents at end of period	675.1	1,127.9	602.7
Principal Financial Services, Inc. and Other Subsidiaries Combined
Operating activities
Net cash provided by (used in) operating activities	1,601.1	317	1,205
Investing activities
Available-for-sale securities: Purchases	(1,005.8)	(1,085.1)	(1,025.9)
Available-for-sale securities: Sales	577.8	546.4	445.9
Available-for-sale securities: Maturities	645.4	778	548.1
Mortgage loans acquired or originated	(333.5)	(325.8)	(188.6)
Mortgage loans sold or repaid	274.7	307.6	254.8
Real estate acquired	(109.7)	(321.7)	(280.9)
Net (purchases) sales of property and equipment	(41.6)	(27.1)	(20.9)
Purchase of interests in subsidiaries, net of cash acquired		(291.2)
Dividends and returns of capital received from (contributed to) unconsolidated entities	1,195	485.6	867.7
Net change in other investments	(922.8)	(319.8)	(290.7)
Net cash provided by (used in) investing activities	279.5	(253.1)	309.5
Financing activities
Excess tax benefits from share-based payment arrangements	6.6	9.3	5.2
Purchase of subsidiary shares from noncontrolling interest	(4.3)	(23.4)	(227.5)
Sale of subsidiary shares to noncontrolling interest	1.9	0.9	0.5
Issuance of long-term debt	6.8	235.5	140.9
Principal repayments of long-term debt	(47.5)	(116.4)	(81.1)
Net proceeds from (repayments of) short-term borrowings	(131.4)	157	(118.3)
Capital received from (dividends and capital paid to) parent	(1,298.4)	(684)	(1,172.9)
Investment contract deposits	305.1	277.5	289.3
Investment contract withdrawals	(19.4)	(11.3)	(10.4)
Net increase (decrease) in banking operation deposits	129	91.1	30.7
Other	0.1		(11.8)
Net cash provided by (used in) financing activities	(1,051.5)	(63.8)	(1,155.4)
Net increase (decrease) in cash and cash equivalents	829.1	0.1	359.1
Cash and cash equivalents at beginning of period	1,253.7	1,253.6	894.5
Cash and cash equivalents at end of period	2,082.8	1,253.7	1,253.6
Eliminations, Notes Guarantor
Operating activities
Net cash provided by (used in) operating activities	(1,212.2)	342.2	(481.5)
Investing activities
Available-for-sale securities: Purchases	13.1		10.2
Available-for-sale securities: Sales		(0.6)
Mortgage loans acquired or originated	60.2	227.8	160
Mortgage loans sold or repaid	(49.6)	(62.1)	(119.5)
Dividends and returns of capital received from (contributed to) unconsolidated entities	(2,493.4)	(1,169.6)	(2,040.6)
Net change in other investments	665.3	(339.4)	34
Net cash provided by (used in) investing activities	(1,804.4)	(1,343.9)	(1,955.9)
Financing activities
Purchase of subsidiary shares from noncontrolling interest	1.9	0.9	0.5
Sale of subsidiary shares to noncontrolling interest	(1.9)	(0.9)	(0.5)
Issuance of long-term debt	5.1	(222.4)	(102.4)
Principal repayments of long-term debt	(7.3)	63.8	80.8
Capital received from (dividends and capital paid to) parent	2,493.4	1,169.6	2,040.6
Net cash provided by (used in) financing activities	2,491.2	1,011	2,019
Net increase (decrease) in cash and cash equivalents	(525.4)	9.3	(418.4)
Cash and cash equivalents at beginning of period	(395.5)	(404.8)	13.6
Cash and cash equivalents at end of period	$ (920.9)	$ (395.5)	$ (404.8)

Condensed Consolidating Fina141

Condensed Consolidating Financial Information - Shelf Registration Guarantor, Statements of Financial Position (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Fixed maturities, available-for-sale	$ 54,846.1	$ 49,966.5
Fixed maturities, trading	398.4	686.8
Equity securities, available-for-sale	98.9	104.5
Equity securities, trading	1,413.4	1,202.7
Mortgage loans	13,230.2	12,339.4
Real estate	1,368.8	1,451.8
Policy loans	823.8	817.1
Investment in unconsolidated entities	773.2	632.7
Other investments	2,882.7	2,619
Cash and cash equivalents	2,719.6	2,564.8	$ 1,863.9	$ 2,371.8
Accrued investment income	580.6	545.6
Premiums due and other receivables	1,361.9	1,429.3
Deferred acquisition costs	3,380.2	3,276.1	2,993	3,077
Property and equipment	699	633.8
Goodwill	1,020.8	1,009	1,007.4
Other intangibles	1,325.3	1,359.2
Separate account assets	139,832.6	136,978.9
Other assets	1,258.8	1,043.1
Total assets	228,014.3	218,660.3
Liabilities
Contractholder funds	37,953.6	35,716.1
Future policy benefits and claims	29,000.7	25,856.5
Other policyholder funds	890.4	805.4
Short-term debt	51.4	181.1
Long-term debt	3,125.7	3,265.2
Income taxes currently payable	12.9	18.4
Deferred income taxes	972.4	697.2
Separate account liabilities	139,832.6	136,978.9
Other liabilities	5,783.3	5,678.4
Total liabilities	217,623	209,197.2
Redeemable noncontrolling interest	97.5	85.7	58	247.2
Stockholders' equity
Common stock	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Noncontrolling interest	66.5	65.8
Total stockholders' equity	10,293.8	9,377.4	10,232	9,777
Total liabilities and stockholders' equity	228,014.3	218,660.3
Principal Financial Group, Inc. Parent Only
Assets
Investment in unconsolidated entities	12,597.9	12,223.4
Other investments	9.8	9.7
Cash and cash equivalents	882.6	578.7	412.4	131.5
Other assets	573.7	458
Total assets	14,064	13,269.8
Liabilities
Long-term debt	3,126.4	3,223.8
Other liabilities	710.3	734.4
Total liabilities	3,836.7	3,958.2
Stockholders' equity
Common stock	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Total stockholders' equity	10,227.3	9,311.6
Total liabilities and stockholders' equity	14,064	13,269.8
Principal Financial Services, Inc. Only
Assets
Investment in unconsolidated entities	12,532.4	12,209.1
Other investments	135.9	185.9
Cash and cash equivalents	1,203.4	730.5	907.2	688.7
Accrued investment income	0.1
Premiums due and other receivables	0.3	0.1
Other assets	185.6	205.2
Total assets	14,057.7	13,330.8
Liabilities
Long-term debt	142.1	156
Income taxes currently payable		3.2
Other liabilities	1,411.3	1,032.9
Total liabilities	1,553.4	1,192.1
Stockholders' equity
Additional paid-in capital	9,010.9	9,000
Retained earnings (accumulated deficit)	3,724.3	3,522.3
Accumulated other comprehensive income (loss)	(230.9)	(383.6)
Total stockholders' equity attributable to Principal Financial Group, Inc.	12,504.3	12,138.7
Total stockholders' equity	12,504.3	12,138.7
Total liabilities and stockholders' equity	14,057.7	13,330.8
Principal Life Insurance Company and Other Subsidiaries Combined
Assets
Fixed maturities, available-for-sale	54,846.1	49,966.5
Fixed maturities, trading	398.4	686.8
Equity securities, available-for-sale	98.9	104.5
Equity securities, trading	1,413.4	1,202.7
Mortgage loans	13,230.2	12,339.4
Real estate	1,368.8	1,451.8
Policy loans	823.8	817.1
Investment in unconsolidated entities	697.5	583.2
Other investments	2,737	2,423.4
Cash and cash equivalents	2,114.8	2,413.3	1,598	2,384
Accrued investment income	580.5	545.6
Premiums due and other receivables	1,503.1	1,584.6
Deferred acquisition costs	3,380.2	3,276.1
Property and equipment	699	633.8
Goodwill	1,020.8	1,009
Other intangibles	1,325.3	1,359.2
Separate account assets	139,832.6	136,978.9
Other assets	1,200.9	1,065.4
Total assets	227,271.3	218,441.3
Liabilities
Contractholder funds	37,953.6	35,716.1
Future policy benefits and claims	29,000.7	25,856.5
Other policyholder funds	890.4	805.4
Short-term debt	127.9	290
Long-term debt	(0.8)	41.4
Income taxes currently payable	68.3	69.6
Deferred income taxes	1,619.3	1,325.2
Separate account liabilities	139,832.6	136,978.9
Other liabilities	4,962.1	4,912.9
Total liabilities	214,454.1	205,996
Redeemable noncontrolling interest	97.5	85.7
Stockholders' equity
Common stock	17.8	17.8
Additional paid-in capital	10,045.9	9,888.7
Retained earnings (accumulated deficit)	2,940.2	2,905.9
Accumulated other comprehensive income (loss)	(348.7)	(516.6)
Treasury stock, at cost	(2)	(2)
Total stockholders' equity attributable to Principal Financial Group, Inc.	12,653.2	12,293.8
Noncontrolling interest	66.5	65.8
Total stockholders' equity	12,719.7	12,359.6
Total liabilities and stockholders' equity	227,271.3	218,441.3
Eliminations, Shelf Registration Debt Guarantor
Assets
Investment in unconsolidated entities	(25,054.6)	(24,383)
Cash and cash equivalents	(1,481.2)	(1,157.7)	$ (1,053.7)	$ (832.4)
Premiums due and other receivables	(141.5)	(155.4)
Other assets	(701.4)	(685.5)
Total assets	(27,378.7)	(26,381.6)
Liabilities
Short-term debt	(76.5)	(108.9)
Long-term debt	(142)	(156)
Income taxes currently payable	(55.4)	(54.4)
Deferred income taxes	(646.9)	(628)
Other liabilities	(1,300.4)	(1,001.8)
Total liabilities	(2,221.2)	(1,949.1)
Stockholders' equity
Common stock	(17.8)	(17.8)
Additional paid-in capital	(19,056.8)	(18,888.7)
Retained earnings (accumulated deficit)	(6,664.5)	(6,428.2)
Accumulated other comprehensive income (loss)	579.6	900.2
Treasury stock, at cost	2	2
Total stockholders' equity attributable to Principal Financial Group, Inc.	(25,157.5)	(24,432.5)
Total stockholders' equity	(25,157.5)	(24,432.5)
Total liabilities and stockholders' equity	$ (27,378.7)	$ (26,381.6)

Condensed Consolidating Fina142

Condensed Consolidating Financial Information - Shelf Registration Guarantor, Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Premiums and other considerations									$ 5,299.1	$ 5,310.3	$ 3,722.9
Fees and other revenues									3,627.4	3,653.1	3,482.1
Net investment income (loss)									3,296.5	3,052.1	3,257.9
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									269.5	(20.9)	92.7
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities									(98.8)	(0.8)	23.8
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income									0.4	(29.4)	(101.8)
Net impairment (losses) recoveries on available-for-sale securities									(98.4)	(30.2)	(78)
Net realized capital gains (losses)									171.1	(51.1)	14.7
Total revenues	$ 3,513.8	$ 2,818	$ 3,025.7	$ 3,036.6	$ 2,807	$ 3,240.9	$ 3,259.2	$ 2,657.3	12,394.1	11,964.4	10,477.6
Expenses
Benefits, claims and settlement expenses									6,913.2	6,697.7	5,231
Dividends to policyholders									156.6	163.5	177.4
Operating expenses									3,732.6	3,672.4	3,574.3
Total expenses	3,132.5	2,447.3	2,625.8	2,596.8	2,498	2,871.7	2,964.7	2,199.2	10,802.4	10,533.6	8,982.7
Income (loss) before income taxes									1,591.7	1,430.8	1,494.9
Income taxes (benefits)									229.9	177.6	318.5
Net income (loss)	338.2	327.4	327	369.2	258.3	300.9	264.9	429.1	1,361.8	1,253.2	1,176.4
Net income (loss) attributable to noncontrolling interest									45.3	19.2	32.3
Net income (loss) attributable to Principal Financial Group, Inc.									1,316.5	1,234	1,144.1
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Net income (loss) available to common stockholders	318	308.2	322.3	368	253.6	300.4	241.1	414.2	1,316.5	1,209.3	1,111.1
Net income (loss)	$ 338.2	$ 327.4	$ 327	$ 369.2	$ 258.3	$ 300.9	$ 264.9	$ 429.1	1,361.8	1,253.2	1,176.4
Other comprehensive income (loss)									221	(943.1)	(144.1)
Comprehensive income (loss)									1,582.8	310.1	1,032.3
Principal Financial Group, Inc. Parent Only
Revenues
Net investment income (loss)									3.4	1.6	0.5
Total revenues									3.4	1.6	0.5
Expenses
Operating expenses									312.3	175.4	144.3
Total expenses									312.3	175.4	144.3
Income (loss) before income taxes									(308.9)	(173.8)	(143.8)
Income taxes (benefits)									(134.9)	(71.2)	(86.3)
Equity in the net income (loss) of subsidiaries									1,490.5	1,336.6	1,201.6
Net income (loss)									1,316.5	1,234	1,144.1
Net income (loss) attributable to Principal Financial Group, Inc.									1,316.5	1,234	1,144.1
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Net income (loss) available to common stockholders										1,209.3	1,111.1
Net income (loss)									1,316.5	1,234	1,144.1
Other comprehensive income (loss)									218.8	(988)	(198.8)
Comprehensive income (loss)									1,535.3	246	945.3
Principal Financial Services, Inc. Only
Revenues
Fees and other revenues									0.9	0.3	0.3
Net investment income (loss)									25.2	15.6	0.7
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									(4.5)	(0.7)	3.8
Net realized capital gains (losses)									(4.5)	(0.7)	3.8
Total revenues									21.6	15.2	4.8
Expenses
Operating expenses									9.7	10.8	12.2
Total expenses									9.7	10.8	12.2
Income (loss) before income taxes									11.9	4.4	(7.4)
Income taxes (benefits)									(24.3)	(0.9)	(8.5)
Equity in the net income (loss) of subsidiaries									1,447.3	1,324.4	1,204.8
Net income (loss)									1,483.5	1,329.7	1,205.9
Net income (loss) attributable to Principal Financial Group, Inc.									1,483.5	1,329.7	1,205.9
Net income (loss) available to common stockholders										1,329.7	1,205.9
Net income (loss)									1,483.5	1,329.7	1,205.9
Other comprehensive income (loss)									174.3	(923.4)	101.3
Comprehensive income (loss)									1,657.8	406.3	1,307.2
Principal Life Insurance Company and Other Subsidiaries Combined
Revenues
Premiums and other considerations									5,299.1	5,310.3	3,722.9
Fees and other revenues									3,634	3,653.6	3,482.4
Net investment income (loss)									3,260.4	3,027.5	3,256.8
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									273.9	(20.2)	93
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities									(98.8)	(0.8)	23.8
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income									0.4	(29.4)	(101.8)
Net impairment (losses) recoveries on available-for-sale securities									(98.4)	(30.2)	(78)
Net realized capital gains (losses)									175.5	(50.4)	15
Total revenues									12,369	11,941	10,477.1
Expenses
Benefits, claims and settlement expenses									6,913.2	6,697.7	5,231
Dividends to policyholders									156.6	163.5	177.4
Operating expenses									3,417.5	3,486.5	3,418.3
Total expenses									10,487.3	10,347.7	8,826.7
Income (loss) before income taxes									1,881.7	1,593.3	1,650.4
Income taxes (benefits)									389.1	249.7	413.3
Net income (loss)									1,492.6	1,343.6	1,237.1
Net income (loss) attributable to noncontrolling interest									45.3	19.2	32.3
Net income (loss) attributable to Principal Financial Group, Inc.									1,447.3	1,324.4	1,204.8
Net income (loss) available to common stockholders										1,324.4	1,204.8
Net income (loss)									1,492.6	1,343.6	1,237.1
Other comprehensive income (loss)									191.7	(1,007)	64.4
Comprehensive income (loss)									1,684.3	336.6	1,301.5
Eliminations, Shelf Registration Debt Guarantor
Revenues
Fees and other revenues									(7.5)	(0.8)	(0.6)
Net investment income (loss)									7.5	7.4	(0.1)
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities									0.1		(4.1)
Net realized capital gains (losses)									0.1		(4.1)
Total revenues									0.1	6.6	(4.8)
Expenses
Operating expenses									(6.9)	(0.3)	(0.5)
Total expenses									(6.9)	(0.3)	(0.5)
Income (loss) before income taxes									7	6.9	(4.3)
Equity in the net income (loss) of subsidiaries									(2,937.8)	(2,661)	(2,406.4)
Net income (loss)									(2,930.8)	(2,654.1)	(2,410.7)
Net income (loss) attributable to Principal Financial Group, Inc.									(2,930.8)	(2,654.1)	(2,410.7)
Net income (loss) available to common stockholders										(2,654.1)	(2,410.7)
Net income (loss)									(2,930.8)	(2,654.1)	(2,410.7)
Other comprehensive income (loss)									(363.8)	1,975.3	(111)
Comprehensive income (loss)									$ (3,294.6)	$ (678.8)	$ (2,521.7)

Condensed Consolidating Fina143

Condensed Consolidating Financial Information - Shelf Registration Guarantor, Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net cash provided by (used in) operating activities	$ 3,857.8	$ 4,377.1	$ 3,102.9
Investing activities
Available-for-sale securities: Purchases	(13,763.8)	(9,920.3)	(9,054)
Available-for-sale securities: Sales	1,890.5	1,563	2,512
Available-for-sale securities: Maturities	7,742.8	6,625.9	6,244.7
Mortgage loans acquired or originated	(2,889)	(2,275.1)	(2,169.6)
Mortgage loans sold or repaid	2,068.7	1,687.3	1,793.6
Real estate acquired	(109.7)	(322)	(281.7)
Net (purchases) sales of property and equipment	(154.9)	(136.4)	(136)
Purchase of interests in subsidiaries, net of cash acquired		(291.2)
Net change in other investments	61.5	(98.8)	(81.7)
Net cash provided by (used in) investing activities	(5,153.9)	(3,167.6)	(1,172.7)
Financing activities
Issuance of common stock	37.8	76.1	77.5
Acquisition of treasury stock	(277.3)	(300.6)	(222.7)
Proceeds from financing element derivatives	0.4	0.3	15.1
Payments for financing element derivatives	(87.7)	(82)	(58)
Excess tax benefits from share-based payment arrangements	12	15.7	9.7
Purchase of subsidiary shares from noncontrolling interest	(2.4)	(22.5)	(227)
Dividends to common stockholders	(464.9)	(441)	(376.6)
Dividends to preferred stockholders		(16.5)	(33)
Preferred stock redemption		(550)
Issuance of long-term debt	656.1	804.9	38.5
Principal repayments of long-term debt	(799.3)	(52.6)	(100.3)
Net proceeds from (repayments of) short-term borrowings	(131.4)	157	(118.3)
Investment contract deposits	10,770.9	6,492.3	5,638.4
Investment contract withdrawals	(8,392.7)	(6,666.8)	(7,099.2)
Net increase (decrease) in banking operation deposits	129	91.1	30.7
Other	0.4	(14)	(12.9)
Net cash provided by (used in) financing activities	1,450.9	(508.6)	(2,438.1)
Net increase (decrease) in cash and cash equivalents	154.8	700.9	(507.9)
Cash and cash equivalents at beginning of period	2,564.8	1,863.9	2,371.8
Cash and cash equivalents at end of period	2,719.6	2,564.8	1,863.9
Principal Financial Group, Inc. Parent Only
Operating activities
Net cash provided by (used in) operating activities	(188.6)	(85.1)	(81.6)
Investing activities
Net (purchases) sales of property and equipment	(0.1)
Dividends and returns of capital received from (contributed to) unconsolidated entities	1,295.3	685.5	917.7
Net change in other investments	1.3	5.4	(0.7)
Net cash provided by (used in) investing activities	1,296.5	690.9	917
Financing activities
Issuance of common stock	37.8	76.1	77.5
Acquisition of treasury stock	(277.3)	(300.6)	(222.7)
Excess tax benefits from share-based payment arrangements	0.7	0.7	0.3
Dividends to common stockholders	(464.9)	(441)	(376.6)
Dividends to preferred stockholders		(16.5)	(33)
Preferred stock redemption		(550)
Issuance of long-term debt	644.2	791.8
Principal repayments of long-term debt	(744.5)
Net cash provided by (used in) financing activities	(804)	(439.5)	(554.5)
Net increase (decrease) in cash and cash equivalents	303.9	166.3	280.9
Cash and cash equivalents at beginning of period	578.7	412.4	131.5
Cash and cash equivalents at end of period	882.6	578.7	412.4
Principal Financial Services, Inc. Only
Operating activities
Net cash provided by (used in) operating activities	255.7	338.5	(16.6)
Investing activities
Dividends and returns of capital received from (contributed to) unconsolidated entities	1,583.3	499.5	1,133.8
Net change in other investments	(56.8)	(485.2)	19
Net cash provided by (used in) investing activities	1,526.5	14.3	1,152.8
Financing activities
Issuance of long-term debt	6	156
Principal repayments of long-term debt	(20)
Capital received from (dividends and capital paid to) parent	(1,295.3)	(685.5)	(917.7)
Net cash provided by (used in) financing activities	(1,309.3)	(529.5)	(917.7)
Net increase (decrease) in cash and cash equivalents	472.9	(176.7)	218.5
Cash and cash equivalents at beginning of period	730.5	907.2	688.7
Cash and cash equivalents at end of period	1,203.4	730.5	907.2
Principal Life Insurance Company and Other Subsidiaries Combined
Operating activities
Net cash provided by (used in) operating activities	3,983.8	4,615.2	3,456.7
Investing activities
Available-for-sale securities: Purchases	(13,763.8)	(9,920.3)	(9,054)
Available-for-sale securities: Sales	1,890.5	1,563	2,512
Available-for-sale securities: Maturities	7,742.8	6,625.9	6,244.7
Mortgage loans acquired or originated	(2,889)	(2,275.1)	(2,169.6)
Mortgage loans sold or repaid	2,068.7	1,687.3	1,793.6
Real estate acquired	(109.7)	(322)	(281.7)
Net (purchases) sales of property and equipment	(154.8)	(136.4)	(136)
Purchase of interests in subsidiaries, net of cash acquired		(291.2)
Net change in other investments	293.7	(116.8)	3.6
Net cash provided by (used in) investing activities	(4,921.6)	(3,185.6)	(1,087.4)
Financing activities
Proceeds from financing element derivatives	0.4	0.3	15.1
Payments for financing element derivatives	(87.7)	(82)	(58)
Excess tax benefits from share-based payment arrangements	11.3	15	9.4
Purchase of subsidiary shares from noncontrolling interest	(2.4)	(22.5)	(227)
Issuance of long-term debt	11.9	77	38.5
Principal repayments of long-term debt	(54.8)	(116.5)	(100.3)
Net proceeds from (repayments of) short-term borrowings	(163.7)	111.3	(256.2)
Capital received from (dividends and capital paid to) parent	(1,583.3)	(499.5)	(1,133.8)
Investment contract deposits	10,770.9	6,492.3	5,638.4
Investment contract withdrawals	(8,392.7)	(6,666.8)	(7,099.2)
Net increase (decrease) in banking operation deposits	129	91.1	30.7
Other	0.4	(14)	(12.9)
Net cash provided by (used in) financing activities	639.3	(614.3)	(3,155.3)
Net increase (decrease) in cash and cash equivalents	(298.5)	815.3	(786)
Cash and cash equivalents at beginning of period	2,413.3	1,598	2,384
Cash and cash equivalents at end of period	2,114.8	2,413.3	1,598
Eliminations, Shelf Registration Debt Guarantor
Operating activities
Net cash provided by (used in) operating activities	(193.1)	(491.5)	(255.6)
Investing activities
Dividends and returns of capital received from (contributed to) unconsolidated entities	(2,878.6)	(1,185)	(2,051.5)
Net change in other investments	(176.7)	497.8	(103.6)
Net cash provided by (used in) investing activities	(3,055.3)	(687.2)	(2,155.1)
Financing activities
Issuance of long-term debt	(6)	(219.9)
Principal repayments of long-term debt	20	63.9
Net proceeds from (repayments of) short-term borrowings	32.3	45.7	137.9
Capital received from (dividends and capital paid to) parent	2,878.6	1,185	2,051.5
Net cash provided by (used in) financing activities	2,924.9	1,074.7	2,189.4
Net increase (decrease) in cash and cash equivalents	(323.5)	(104)	(221.3)
Cash and cash equivalents at beginning of period	(1,157.7)	(1,053.7)	(832.4)
Cash and cash equivalents at end of period	$ (1,481.2)	$ (1,157.7)	$ (1,053.7)

Schedule I - Summary of Inve144

Schedule I - Summary of Investments - Other Than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2016USD ($)
Summary of Investments - Other Than Investments in Related Parties
Cost	$ 74,179.6
Amount as shown in the Consolidated Statement of Financial Position	75,835.5
Fixed maturities | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	53,184.2
Value	54,846.1
Amount as shown in the Consolidated Statement of Financial Position	54,846.1
Fixed maturities | Trading
Summary of Investments - Other Than Investments in Related Parties
Cost	398.4
Value	398.4
Amount as shown in the Consolidated Statement of Financial Position	398.4
U.S. government and agencies | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	1,426.7
Value	1,433
Amount as shown in the Consolidated Statement of Financial Position	1,433
States and political subdivisions | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	5,463.9
Value	5,569.2
Amount as shown in the Consolidated Statement of Financial Position	5,569.2
Non-U.S. governments | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	781.7
Value	893.6
Amount as shown in the Consolidated Statement of Financial Position	893.6
Public utilities | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	4,412.6
Value	3,963.8
Amount as shown in the Consolidated Statement of Financial Position	3,963.8
Redeemable preferred stock | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	33.8
Value	37
Amount as shown in the Consolidated Statement of Financial Position	37
All other corporate bonds | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	28,253.3
Value	30,191.6
Amount as shown in the Consolidated Statement of Financial Position	30,191.6
Residential mortgage-backed pass-through securities | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	2,798
Value	2,834.7
Amount as shown in the Consolidated Statement of Financial Position	2,834.7
Commercial mortgage-backed securities | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	4,153.2
Value	4,096.5
Amount as shown in the Consolidated Statement of Financial Position	4,096.5
Collateralized debt obligations | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	780.1
Value	758.6
Amount as shown in the Consolidated Statement of Financial Position	758.6
Other debt obligations | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	5,080.9
Value	5,068.1
Amount as shown in the Consolidated Statement of Financial Position	5,068.1
Equity securities | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	104.9
Value	98.9
Amount as shown in the Consolidated Statement of Financial Position	98.9
Equity securities | Trading
Summary of Investments - Other Than Investments in Related Parties
Cost	1,413.4
Value	1,413.4
Amount as shown in the Consolidated Statement of Financial Position	1,413.4
Common stocks: Banks, trust and insurance companies | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	48.3
Value	38.5
Amount as shown in the Consolidated Statement of Financial Position	38.5
Common stocks: Industrial, miscellaneous and all other | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	1.2
Value	2.5
Amount as shown in the Consolidated Statement of Financial Position	2.5
Non-redeemable preferred stock | Available-for-sale
Summary of Investments - Other Than Investments in Related Parties
Cost	55.4
Value	57.9
Amount as shown in the Consolidated Statement of Financial Position	57.9
Mortgage loans
Summary of Investments - Other Than Investments in Related Parties
Cost	13,230.2
Amount as shown in the Consolidated Statement of Financial Position	13,230.2
Real estate acquired in satisfaction of debt
Summary of Investments - Other Than Investments in Related Parties
Cost	88.9
Amount as shown in the Consolidated Statement of Financial Position	88.9
Other real estate
Summary of Investments - Other Than Investments in Related Parties
Cost	1,279.9
Amount as shown in the Consolidated Statement of Financial Position	1,279.9
Policy loans
Summary of Investments - Other Than Investments in Related Parties
Cost	823.8
Amount as shown in the Consolidated Statement of Financial Position	823.8
Investments: Other investments
Summary of Investments - Other Than Investments in Related Parties
Cost	3,655.9
Amount as shown in the Consolidated Statement of Financial Position	$ 3,655.9

Schedule II - Condensed Fina145

Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Financial Position (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Cash and cash equivalents	$ 2,719.6	$ 2,564.8	$ 1,863.9	$ 2,371.8
Other investments	3,655.9	3,251.7
Deferred income tax assets	103.9	96
Investment in subsidiaries	773.2	632.7
Total assets	228,014.3	218,660.3
Liabilities
Long-term debt	3,125.7	3,265.2
Total liabilities	217,623	209,197.2
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 469.2 million and 466.2 million shares issued, and 287.7 million and 291.4 million shares outstanding in 2016 and 2015	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost (181.5 million and 174.8 million shares in 2016 and 2015)	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Total liabilities and stockholders' equity	228,014.3	218,660.3
Principal Financial Group, Inc. Parent Only
Assets
Cash and cash equivalents	882.6	578.7	$ 412.4	$ 131.5
Other investments	9.8	9.7
Income taxes receivable	85.6	21.3
Deferred income tax assets	473.2	427.4
Amounts receivable from subsidiaries	4.5	8.9
Other assets	10.4	0.4
Investment in subsidiaries	12,597.9	12,223.4
Total assets	14,064	13,269.8
Liabilities
Long-term debt	3,126.4	3,223.8
Accrued investment payable	23.4	25.8
Pension liability	686.4	708.6
Other liabilities	0.5
Total liabilities	3,836.7	3,958.2
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 469.2 million and 466.2 million shares issued, and 287.7 million and 291.4 million shares outstanding in 2016 and 2015	4.7	4.7
Additional paid-in capital	9,686	9,544.8
Retained earnings (accumulated deficit)	7,720.4	6,875.9
Accumulated other comprehensive income (loss)	(675.2)	(882.5)
Treasury stock, at cost (181.5 million and 174.8 million shares in 2016 and 2015)	(6,508.6)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,227.3	9,311.6
Total liabilities and stockholders' equity	$ 14,064	$ 13,269.8

Schedule II - Condensed Fina146

Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Financial Position - Parenthetical (Details) - $ / shares shares in Millions	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	2,500	2,500
Common stock, issued (in shares)	469.2	466.2
Common stock, outstanding (in shares)	287.7	291.4
Treasury stock (in shares)	181.5	174.8
Principal Financial Group, Inc. Parent Only
Condensed Financial Statements, Captions [Line Items]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	2,500	2,500
Common stock, issued (in shares)	469.2	466.2
Common stock, outstanding (in shares)	287.7	291.4
Treasury stock (in shares)	181.5	174.8

Schedule II - Condensed Fina147

Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Net investment income (loss)									$ 3,296.5	$ 3,052.1	$ 3,257.9
Total revenues	$ 3,513.8	$ 2,818	$ 3,025.7	$ 3,036.6	$ 2,807	$ 3,240.9	$ 3,259.2	$ 2,657.3	12,394.1	11,964.4	10,477.6
Expenses
Other operating costs and expenses									3,732.6	3,672.4	3,574.3
Total expenses	3,132.5	2,447.3	2,625.8	2,596.8	2,498	2,871.7	2,964.7	2,199.2	10,802.4	10,533.6	8,982.7
Income (loss) before income taxes									1,591.7	1,430.8	1,494.9
Income taxes (benefits)									229.9	177.6	318.5
Net income (loss) attributable to Principal Financial Group, Inc.									1,316.5	1,234	1,144.1
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Net income (loss) available to common stockholders	$ 318	$ 308.2	$ 322.3	$ 368	$ 253.6	$ 300.4	$ 241.1	$ 414.2	1,316.5	1,209.3	1,111.1
Principal Financial Group, Inc. Parent Only
Revenues
Net investment income (loss)									3.4	1.6	0.5
Total revenues									3.4	1.6	0.5
Expenses
Other operating costs and expenses									312.3	175.4	144.3
Total expenses									312.3	175.4	144.3
Income (loss) before income taxes									(308.9)	(173.8)	(143.8)
Income taxes (benefits)									(134.9)	(71.2)	(86.3)
Equity in the net income (loss) of subsidiaries									1,490.5	1,336.6	1,201.6
Net income (loss) attributable to Principal Financial Group, Inc.									1,316.5	1,234	1,144.1
Preferred stock dividends										16.5	33
Excess of redemption value over carrying value of preferred shares redeemed										8.2
Net income (loss) available to common stockholders									$ 1,316.5	$ 1,209.3	$ 1,111.1

Schedule II - Condensed Fina148

Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income (loss)	$ 338.2	$ 327.4	$ 327	$ 369.2	$ 258.3	$ 300.9	$ 264.9	$ 429.1	$ 1,361.8	$ 1,253.2	$ 1,176.4
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Current and deferred income taxes (benefits)									45.8	(66.5)	175.9
Stock-based compensation									84.4	84.5	75.3
Other									(73.8)	141.2	(189.1)
Net cash provided by (used in) operating activities									3,857.8	4,377.1	3,102.9
Investing activities
Net (purchases) sales of property and equipment									(154.9)	(136.4)	(136)
Net change in other investments									61.5	(98.8)	(81.7)
Net cash provided by (used in) investing activities									(5,153.9)	(3,167.6)	(1,172.7)
Financing activities
Issuance of common stock									37.8	76.1	77.5
Acquisition of treasury stock									(277.3)	(300.6)	(222.7)
Excess tax benefits from share-based payment arrangements									12	15.7	9.7
Dividends to common stockholders									(464.9)	(441)	(376.6)
Dividends to preferred stockholders										(16.5)	(33)
Preferred stock redemption										(550)
Principal repayments of long-term debt									(799.3)	(52.6)	(100.3)
Issuance of long-term debt									656.1	804.9	38.5
Net cash provided by (used in) financing activities									1,450.9	(508.6)	(2,438.1)
Net increase (decrease) in cash and cash equivalents									154.8	700.9	(507.9)
Cash and cash equivalents at beginning of period				2,564.8				1,863.9	2,564.8	1,863.9	2,371.8
Cash and cash equivalents at end of period	2,719.6				2,564.8				2,719.6	2,564.8	1,863.9
Principal Financial Group, Inc. Parent Only
Operating activities
Net income (loss)									1,316.5	1,234	1,144.1
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in the net (income) loss of subsidiaries									(1,490.5)	(1,336.6)	(1,201.6)
Current and deferred income taxes (benefits)									(60.3)	(20.9)	(225.9)
Stock-based compensation									3.6	3.9	3.1
Other									42.1	34.5	198.7
Net cash provided by (used in) operating activities									(188.6)	(85.1)	(81.6)
Investing activities
Net (purchases) sales of property and equipment									(0.1)
Net change in other investments									1.3	5.4	(0.7)
Dividends and returns of capital received from (contributed to) unconsolidated entities									1,295.3	685.5	917.7
Net cash provided by (used in) investing activities									1,296.5	690.9	917
Financing activities
Issuance of common stock									37.8	76.1	77.5
Acquisition of treasury stock									(277.3)	(300.6)	(222.7)
Excess tax benefits from share-based payment arrangements									0.7	0.7	0.3
Dividends to common stockholders									(464.9)	(441)	(376.6)
Dividends to preferred stockholders										(16.5)	(33)
Preferred stock redemption										(550)
Principal repayments of long-term debt									(744.5)
Issuance of long-term debt									644.2	791.8
Net cash provided by (used in) financing activities									(804)	(439.5)	(554.5)
Net increase (decrease) in cash and cash equivalents									303.9	166.3	280.9
Cash and cash equivalents at beginning of period				$ 578.7				$ 412.4	578.7	412.4	131.5
Cash and cash equivalents at end of period	$ 882.6				$ 578.7				$ 882.6	$ 578.7	$ 412.4

Schedule II - Condensed Fina149

Schedule II - Condensed Financial Information of Registrant (Parent Only) - Financial Statement Footnotes (Details) - Principal Financial Group, Inc. Parent Only - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Dividends and Returns of Capital Received from (Contributed to) Unconsolidated Entity
Dividends and returns of capital received from (contributed to) unconsolidated entities	$ 1,295.3	$ 685.5	$ 917.7
Supplemental Disclosures of Non-Cash Investing Activity
Non-cash increase in investment in subsidiaries	$ 74.6

Schedule III - Supplementary150

Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplementary Insurance Information
Deferred acquisition costs	$ 3,380.2	$ 3,276.1	$ 2,993	$ 3,077
Future policy benefits and claims	29,000.7	25,856.5
Contractholder and other policyholder funds	38,844	36,521.5
Premiums and other considerations	5,299.1	5,310.3	3,722.9
Net investment income (loss)	3,296.5	3,052.1	3,257.9
Benefits, claims and settlement expenses	6,913.2	6,697.7	5,231
Amortization of deferred acquisition costs	285.1	270.8	367.2
Other operating expenses	3,447.5	3,401.6	3,207.1
Retirement and Income Solutions
Supplementary Insurance Information
Deferred acquisition costs	812.7	854
Future policy benefits and claims	15,455	13,229.8
Contractholder and other policyholder funds	30,796.8	28,651.5
Premiums and other considerations	2,860.9	3,011.4	1,584.5
Net investment income (loss)	1,931.2	1,749	1,857.7
Benefits, claims and settlement expenses	4,108.3	4,158.4	2,766.9
Amortization of deferred acquisition costs	161.4	158.2	163.6
Other operating expenses	1,114.3	1,126.8	1,056.9
Principal Global Investors
Supplementary Insurance Information
Net investment income (loss)	12.6	8.1	10.5
Other operating expenses	935.8	943.4	895.3
Principal International
Supplementary Insurance Information
Deferred acquisition costs	196	218.8
Future policy benefits and claims	4,182.2	3,634.9
Contractholder and other policyholder funds	1,316.9	1,403.9
Premiums and other considerations	274.6	252.9	225.7
Net investment income (loss)	491.4	495.9	591
Benefits, claims and settlement expenses	584.6	573.9	622.9
Amortization of deferred acquisition costs	22.5	19.1	18.7
Other operating expenses	365.5	368.9	342.8
U.S. Insurance Solutions
Supplementary Insurance Information
Deferred acquisition costs	2,371.5	2,203.3
Future policy benefits and claims	9,171.5	8,757.2
Contractholder and other policyholder funds	7,060.7	6,783.5
Premiums and other considerations	2,163.6	2,045.9	1,913.8
Net investment income (loss)	751.2	717.8	714.8
Benefits, claims and settlement expenses	2,221.4	1,963.5	1,847.9
Amortization of deferred acquisition costs	101.2	93.5	184.9
Other operating expenses	796.4	788.1	714.7
Corporate
Supplementary Insurance Information
Future policy benefits and claims	192	234.6
Contractholder and other policyholder funds	(330.4)	(317.4)
Premiums and other considerations		0.1	(1.1)
Net investment income (loss)	110.1	81.3	83.9
Benefits, claims and settlement expenses	(1.1)	1.9	(6.7)
Other operating expenses	$ 235.5	$ 174.4	$ 197.4

Schedule IV - Reinsurance (Deta

Schedule IV - Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Life insurance in force
Life insurance in force gross amount	$ 437,977.4	$ 390,603.3	$ 354,951.9
Life insurance in force ceded to other companies	242,777.7	184,588.9	177,418.6
Life insurance in force assumed from other companies	1,087.8	1,187.1	1,317.7
Life insurance in force net amount	$ 196,287.5	$ 207,201.5	$ 178,851
Life insurance in force, percentage of amount assumed to net (as a percent)	0.60%	0.60%	0.70%
Premiums:
Premiums gross amount	$ 5,753.8	$ 5,710.8	$ 4,123.7
Premiums ceded to other companies	456.4	402.4	402.9
Premiums assumed from other companies	1.7	1.9	2.1
Premiums net amount	5,299.1	5,310.3	$ 3,722.9
Premiums percentage of amount assumed to net (as a percent)			0.10%
Life insurance and annuities
Premiums:
Premiums gross amount	4,137.1	4,208.7	$ 2,725.4
Premiums ceded to other companies	285.2	255.3	228.1
Premiums assumed from other companies	1.7	1.9	2.1
Premiums net amount	3,853.6	3,955.3	$ 2,499.4
Premiums percentage of amount assumed to net (as a percent)			0.10%
Accident and health insurance
Premiums:
Premiums gross amount	1,616.7	1,502.1	$ 1,398.3
Premiums ceded to other companies	171.2	147.1	174.8
Premiums net amount	$ 1,445.5	$ 1,355	$ 1,223.5