Morningstar (MORN) 10-K 1 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 15, 2019	Jun. 30, 2018
Document and Entity Information Abstract
Entity Registrant Name	MORNINGSTAR, INC.
Entity Central Index Key	1,289,419
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		42,587,504
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Public Float			$ 2,400

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue	$ 1,019.9	$ 911.7	$ 798.6
Operating expense:
Cost of revenue	411.1	386.6	344.3
Sales and marketing	148.5	134.3	97.6
General and administrative	147.8	129.8	105.2
Depreciation and amortization	96.7	91.2	70.7
Total operating expense	804.1	741.9	617.8
Operating income	215.8	169.8	180.8
Non-operating income:
Interest income (expense), net	(1.8)	(3.6)	0.3
Gain on sale of investments, reclassified from other comprehensive income	1	3.2	0.6
Gain on sale of business	0	16.7	0
Gain on sale of a product line	10.5	0	0
Gain on sale of equity investments	5.6	0	0
Holding gain upon acquisition of additional ownership of equity-method investments	0	0	37.1
Other income (expense), net	1.8	(5)	6.1
Non-operating income, net	17.1	11.3	44.1
Income before income taxes and equity in net loss of unconsolidated entities	232.9	181.1	224.9
Equity in net loss of unconsolidated entities	(2.1)	(1.3)	(0.2)
Income tax expense	47.8	42.9	63.7
Consolidated net income	$ 183	$ 136.9	$ 161
Net income per share attributable to Morningstar, Inc.:
Basic net income per share attributable to Morningstar, Inc. (in dollars per share)	$ 4.30	$ 3.21	$ 3.74
Diluted net income per share attributable to Morningstar, Inc. (in dollars per share)	4.25	3.18	3.72
Dividends per common share:
Dividends declared per common share (in dollars per share)	1.03	0.94	0.89
Dividends paid per common share (in dollars per share)	$ 1	$ 0.92	$ 0.88
Weighted average shares outstanding:
Basic (in shares)	42.6	42.7	43
Diluted (in shares)	43	43	43.3

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Consolidated net income	$ 183	$ 136.9	$ 161
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(26.6)	33.4	(27.8)
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	(1)	3.4	3.3
Reclassification of gains included in net income	(0.8)	(1.9)	(2.4)
Other comprehensive income (loss)	(28.4)	34.9	(26.9)
Comprehensive income	$ 154.6	$ 171.8	$ 134.1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 369.3	$ 308.2
Investments	26.6	45.1
Accounts receivable, less allowance for doubtful accounts of $4.0 and $3.2, respectively	172.2	148.2
Income tax receivable, net	1.8	0
Deferred commissions	14.8	0
Other current assets	16.9	28.3
Total current assets	601.6	529.8
Property, equipment, and capitalized software, net	143.5	147.4
Investments in unconsolidated entities	63.1	62
Goodwill	556.7	564.9
Intangible assets, net	73.9	95.4
Deferred commissions, non-current	10.3	0
Other assets	4.7	6.2
Total assets	1,453.8	1,405.7
Current liabilities:
Accounts payable and accrued liabilities	54.4	49.2
Accrued compensation	109.5	92
Deferred revenue	195.8	171.3
Other current liabilities	3.1	10.7
Total current liabilities	362.8	323.2
Accrued compensation	11.8	11.7
Deferred tax liability, net	22.2	23.6
Long-term debt	70	180
Deferred rent	24.5	26.9
Deferred revenue, non-current	14.2	14.2
Other long-term liabilities	13.6	21.2
Total liabilities	519.1	600.8
Morningstar, Inc. shareholders’ equity:
Common stock, no par value, 200,000,000 shares authorized, of which 42,624,118 and 42,547,707 shares were outstanding as of December 31, 2018 and December 31, 2017, respectively	0	0
Treasury stock at cost, 10,816,672 and 10,633,637 shares as of December 31, 2018 and December 31, 2017, respectively	(726.8)	(708.2)
Additional paid-in capital	621.7	601
Retained earnings	1,114.8	958.7
Accumulated other comprehensive loss:
Currency translation adjustment	(74.5)	(47.9)
Unrealized gain (loss) on available-for-sale investments	(0.5)	1.3
Total accumulated other comprehensive loss	(75)	(46.6)
Total equity	934.7	804.9
Total liabilities and equity	$ 1,453.8	$ 1,405.7

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4	$ 3.2
Common stock, no par value
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares outstanding	46,624,118	42,547,707
Treasury stock, shares	10,816,672	10,633,637

Consolidated Statement of Equit

Consolidated Statement of Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non Controlling Interests
Balance at Dec. 31, 2015	$ 640.6		$ (619.8)	$ 575.5	$ 739.2	$ (54.6)	$ 0.3
Balance (in shares) at Dec. 31, 2015		43,403,076
Increase (Decrease) in Stockholders' Equity
Net income	161				161		0
Other Comprehensive Income (loss)
Unrealized gain on available-for-sale investments, net of income tax	3.3					3.3
Reclassification of adjustments for gains included in net income, net of income tax	(2.4)					(2.4)
Foreign currency translation adjustment, net	(27.8)					(27.8)	0
Other comprehensive income (loss)	(26.9)					(26.9)	0
Issuance of common stock related to stock-option exercises and vesting of restricted stock units, net	(4.6)		1.4	(6)
Issuance of common stock related to stock-option exercises and vesting of restricted stock units, net (in shares)		174,911
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition [Abstract]
Stock-based compensation — restricted stock units	14.6			14.6
Stock-based compensation — performance share awards	(0.1)			(0.1)
Dividends declared — common shares outstanding	(38.3)				(38.3)
Common share repurchased	(49.5)		(49.5)
Common share repurchased (in shares)		(644,993)
Balance at Dec. 31, 2016	696.8		(667.9)	584	861.9	(81.5)	0.3
Balance (in shares) at Dec. 31, 2016		42,932,994
Increase (Decrease) in Stockholders' Equity
Net income	136.9				136.9		0
Other Comprehensive Income (loss)
Unrealized gain on available-for-sale investments, net of income tax	3.4					3.4
Reclassification of adjustments for gains included in net income, net of income tax	(1.9)					(1.9)
Foreign currency translation adjustment, net	33.4					33.4	0
Other comprehensive income (loss)	34.9					34.9	0
Issuance of common stock related to stock-option exercises and vesting of restricted stock units, net	(4.6)		1.6	(6.2)
Issuance of common stock related to stock-option exercises and vesting of restricted stock units, net (in shares)		161,445
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition [Abstract]
Stock-based compensation — restricted stock units	16.5			16.5
Stock-based compensation — performance share awards	7.1			7.1
Stock-based compensation — market stock units	0.5			0.5
Dividends declared — common shares outstanding	(40.1)				(40.1)
Purchase of additional interest in majority-owned investment	1.2			0.9	0	0	0.3
Common share repurchased	(41.9)		(41.9)
Common share repurchased (in shares)		(546,732)
Balance at Dec. 31, 2017	$ 804.9	$ 0	(708.2)	601	958.7	(46.6)	0
Balance (in shares) at Dec. 31, 2017	42,547,707	42,547,707
Increase (Decrease) in Stockholders' Equity
Net income	$ 183				183		0
Other Comprehensive Income (loss)
Unrealized gain on available-for-sale investments, net of income tax	(1)					(1)
Reclassification of adjustments for gains included in net income, net of income tax	(0.8)					(0.8)
Foreign currency translation adjustment, net	(26.6)					(26.6)	0
Other comprehensive income (loss)	(28.4)					(28.4)	0
Issuance of common stock related to stock-option exercises and vesting of restricted stock units, net	(13.2)		2.3	(15.5)
Reclassification of awards previously liability-classified that were converted to equity	4.5			4.5
Issuance of common stock related to stock-option exercises and vesting of restricted stock units, net (in shares)		278,656
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition [Abstract]
Stock-based compensation — restricted stock units	19.8			19.8
Stock-based compensation — performance share awards	10.2			10.2
Stock-based compensation — market stock units	1.7			1.7
Dividends declared — common shares outstanding	(43.9)				(43.9)
Common share repurchased	(20.9)		(20.9)
Common share repurchased (in shares)		(202,245)
Balance at Dec. 31, 2018	$ 934.7	$ 0	$ (726.8)	$ 621.7	$ 1,114.8	$ (75)	$ 0
Balance (in shares) at Dec. 31, 2018	46,624,118	42,624,118

Consolidated Statement of Equ_2

Consolidated Statement of Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Unrealized gain on available-for-sale investments, tax	$ 0.7	$ 1.8	$ 1.3
Reclassification of adjustments for gains included in net income, tax	$ 0.3	$ 1.2	$ 1.8

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Consolidated net income	$ 183	$ 136.9	$ 161
Adjustments to reconcile consolidated net income to net cash flows from operating activities:
Depreciation and amortization	96.7	91.2	70.7
Deferred income taxes	(1.1)	(14.1)	4.7
Stock-based compensation expense	31.7	24.1	14.5
Provision for bad debt	2.5	2.3	1.3
Equity in net loss of unconsolidated entities	2.1	1.3	0.2
Gain on sale of business	0	(16.7)	0
Gain on sale of a product line	(10.5)	0	0
Gain on sale of equity investments	(5.6)	0	0
Holding gain upon acquisition of additional ownership of equity-method investments	0	0	(37.1)
Other, net	(2.5)	1.8	(6.8)
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	(29.6)	(1.2)	(0.1)
Other assets	13.4	(7.8)	1.1
Deferred commissions	25.1	0	0
Accounts payable and accrued liabilities	6	0.7	3.4
Accrued compensation	(9.5)	20.2	(8.8)
Income taxes—current	(12.4)	9.7	1
Deferred revenue	28.6	2.5	6.7
Deferred rent	(2)	2.6	(2.9)
Other liabilities	(1.1)	(3.4)	4.8
Cash provided by operating activities	314.8	250.1	213.7
Investing activities
Purchases of investments	(35.7)	(34.9)	(32)
Proceeds from maturities and sales of investments	51.2	42.2	28.6
Capital expenditures	(76.1)	(66.6)	(62.8)
Acquisitions, net of cash acquired	(0.4)	(1)	(191.6)
Proceeds from sale of a business, net	0	23.7	0
Proceeds from sale of a product line	10.5	0	0
Proceeds from sale of equity-method investments	7.9	0	0
Purchases of equity- and cost-method investments	(7.4)	(24.8)	(16.5)
Other, net	0.1	0.6	0.1
Cash used for investing activities	(49.9)	(60.8)	(274.2)
Financing activities
Common shares repurchased	(20.9)	(42.3)	(48.8)
Dividends paid	(42.6)	(39.3)	(37.9)
Proceeds from short-term debt	0	0	40
Repayment of short-term debt	0	0	(15)
Proceeds from long-term debt	0	0	190
Repayment of long-term debt	(110)	(70)	0
Proceeds from stock-option exercises	0.1	0.2	0.4
Employee taxes withheld for restricted stock units	(13.3)	(4.8)	(5)
Other, net	(2.1)	(1.3)	0
Cash provided by (used for) financing activities	(188.8)	(157.5)	123.7
Effect of exchange rate changes on cash and cash equivalents	(15)	17.3	(11.2)
Net increase in cash and cash equivalents	61.1	49.1	52
Cash and cash equivalents—beginning of period	308.2	259.1	207.1
Cash and cash equivalents—end of period	369.3	308.2	259.1
Supplemental disclosure of cash flow information:
Cash paid for income taxes	67	47.1	58
Cash paid for interest	3.7	5.4	1.2
Supplemental information of non-cash investing and financing activities:
Unrealized gain (loss) on available-for-sale investments	(2.7)	2	1.2
Software and equipment obtained under long-term financing arrangement	$ 0	$ 0.6	$ 9

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Morningstar, Inc. and its subsidiaries (Morningstar, we, our, the company) provide independent investment research for investors around the world. We offer an extensive line of products and services for individual investors, financial advisors, asset managers, retirement plan providers and sponsors, and private market/venture capital investors. We have operations in 27 countries.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The acronyms that appear in these Notes to our Consolidated Financial Statements refer to the following: ASC Accounting Standards Codification ASU Accounting Standards Update EITF Emerging Issues Task Force FASB Financial Accounting Standards Board SEC Securities and Exchange Commission Principles of Consolidation. We conduct our business operations through wholly owned or majority-owned operating subsidiaries. The accompanying consolidated financial statements include the accounts of Morningstar, Inc. and our subsidiaries. We consolidate assets, liabilities, and results of operations of subsidiaries in which we have a controlling interest and eliminate all significant intercompany accounts and transactions. We account for investments in entities in which we exercise significant influence, but do not control, using the equity method. As part of our investment management operations, we manage certain funds outside of the U.S. that are considered variable interest entities. For the majority of these variable interest entities, we do not have a variable interest. In cases where we do have a variable interest, we are not the primary beneficiary. Accordingly, we do not consolidate any of these variable interest entities. Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses during the reporting period. Actual results may differ from these estimates. Cash and Cash Equivalents. Cash and cash equivalents consist of cash and investments with original maturities of three months or less. We state them at cost, which approximates fair value. We state the portion of our cash equivalents that are invested in money market funds at fair value, as these funds are actively traded and have quoted market prices. Investments. We account for our investments in accordance with FASB ASC 320, Investments—Debt and Equity Securities. We classify our investments into three categories: held-to-maturity, trading, and available-for-sale. • Held-to-maturity: We classify certain investments, primarily certificates of deposit, as held-to-maturity securities, based on our intent and ability to hold these securities to maturity. We record held-to-maturity investments at amortized cost in our Consolidated Balance Sheets. • Trading: We classify certain other investments, primarily equity securities, as trading securities as these relate mainly to investments tracking the strategies of our newsletter portfolios. We include realized and unrealized gains and losses associated with these investments as a component of our operating income in our Consolidated Statements of Income. We record these securities at their fair value in our Consolidated Balance Sheets. • Available-for-sale: Investments not considered held-to-maturity or trading securities are classified as available-for-sale securities. Available-for-sale securities primarily consist of equity securities, exchange-traded funds, and mutual funds. We report unrealized gains and losses for available-for-sale securities as other comprehensive income (loss), net of related income taxes. We record these securities at their fair value in our Consolidated Balance Sheets. Fair Value Measurements. FASB ASC 820, Fair Value Measurements (FASB ASC 820) defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. Under FASB ASC 820, 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 as of the measurement date. The standard applies whenever other standards require (or permit) assets or liabilities to be measured at fair value. FASB ASC 820 uses a fair value hierarchy based on three broad levels of valuation inputs: • Level 1: Valuations based on quoted prices in active markets for identical assets or liabilities that the company has the ability to access. • Level 2: Valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. • Level 3: Valuations based on inputs that are unobservable and significant to the overall fair value measurement. We provide additional information about our cash equivalents and investments that are subject to valuation under FASB ASC 820 in Note 7 . Concentration of Credit Risk. No single customer is large enough to pose a significant credit risk to our operations or financial condition. For the years ended December 31, 2018 , 2017 , and 2016 , no single customer represented 5% or more of our consolidated revenue. If receivables from our customers become delinquent, we begin a collections process. We maintain an allowance for doubtful accounts based on our estimate of the probable losses of accounts receivable. Property, Equipment, and Depreciation. We state property and equipment at historical cost, net of accumulated depreciation. We depreciate property and equipment primarily using the straight-line method based on the useful life of the asset, which generally is three years. We amortize leasehold improvements over the lease term or their useful lives, whichever is shorter. Computer Software and Internal Product Development Costs. We capitalize certain costs in accordance with FASB ASC 350-40, Internal-Use Software , FASB ASC 350-50, Website Development Costs, and FASB ASC 985, Software . Internal product development costs mainly consist of employee costs for developing new web-based products and certain major enhancements of existing products. We amortize these costs on a straight-line basis over the estimated economic life, which is generally three years. We include capitalized software development costs related to projects that have not been placed into service in our construction in progress balance. The table below summarizes our depreciation expense related to internally developed software for the past three years: (in millions) 2018 2017 2016 Internally developed software depreciation expense $ 42.8 $ 30.6 $ 20.0 The table below summarizes our capitalized software development costs for the past three years: (in millions) 2018 2017 2016 Capitalized software development costs $ 53.5 $ 46.3 $ 28.2 Business Combinations . When we make acquisitions, we allocate the purchase price to the assets acquired, liabilities assumed, and goodwill. We follow FASB ASC 805, Business Combinations . We recognize and measure the fair value of the acquired operation as a whole, as well as the assets acquired and liabilities assumed, at their full fair values as of the date we obtain control, regardless of the percentage ownership in the acquired operation or how the acquisition was achieved. We expense direct costs related to the business combination, such as advisory, accounting, legal, valuation, and other professional fees, as incurred. We recognize restructuring costs, including severance and relocation for employees of the acquired entity, as post-combination expenses unless the target entity meets the criteria of FASB ASC 420, Exit or Disposal Cost Obligations , on the acquisition date. As part of the purchase price allocation, we follow the requirements of FASB ASC 740, Income Taxes. This includes establishing deferred tax assets or liabilities reflecting the difference between the values assigned for financial statement purposes and income tax purposes. In certain acquisitions, the goodwill resulting from the purchase price allocation may not be deductible for income tax purposes. FASB ASC 740 prohibits recognition of a deferred tax asset or liability for temporary differences in goodwill if goodwill is not amortizable and deductible for tax purposes. Goodwill . Changes in the carrying amount of our recorded goodwill are mainly the result of business acquisitions, divestitures, and the effect of foreign currency translations. In accordance with FASB ASC 350, Intangibles—Goodwill and Other , we do not amortize goodwill; instead, goodwill is subject to an impairment test annually, or whenever indicators of impairment exist. An impairment would occur if the carrying amount of a reporting unit exceeded the fair value of that reporting unit. We performed annual impairment reviews in the fourth quarter of 2018 and 2017 . We did not record any impairment losses in 2018 , 2017 , and 2016. Intangible Assets. We amortize intangible assets using the straight-line method over their estimated useful lives, which range from one to 20 years. We have no intangible assets with indefinite useful lives. In accordance with FASB ASC 360-10-35, Subsequent Measurement—Impairment or Disposal of Long-Lived Assets , we review intangible assets for impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. If the value of future undiscounted cash flows is less than the carrying amount of an asset group, we record an impairment loss based on the excess of the carrying amount over the fair value of the asset group. We did not record any impairment losses in 2018 , 2017 , and 2016. Revenue Recognition. On January 1, 2018, we began recognizing revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers . The Company has retained much of the same accounting treatment used to recognize revenue under ASC Topic 606 as under accounting standards in effect in prior periods (see Note 18 for additional information). Under ASC Topic 606, we recognize revenue by applying the following five-step model to each of our customer arrangements: 1. Identify the customer contract; 2. Identify the performance obligations in the contract; 3. Determine the transaction price; 4. Allocate the transaction price to the performance obligations; and 5. Recognize revenue when (or as) performance obligations are satisfied. Revenues are recognized when (or as) performance obligations are satisfied by transferring a promised product or service to the customer. Products or services are transferred when (or as) the customer obtains control of the product or service. The transaction price for a customer arrangement is the amount we expect to be entitled to in exchange for transferring the promised product or service. The transaction price may include fixed amounts, variable amounts, or both. Amounts invoiced in excess of the revenue recognized for the services transferred during the period will result in an increase to deferred revenue. The timing of cash payments is typically thirty to sixty days after the performance obligation has been satisfied and these payments reduce our outstanding accounts receivable. Revenue from contracts with customers is derived from license-based arrangements, asset-based arrangements, and transaction-based arrangements. License-based revenue is generated through subscription contracts with our customers of Morningstar Data, Morningstar Direct, Morningstar Advisor Workstation, Morningstar Enterprise Components, PitchBook Data, and other similar products. Our performance obligations under these contracts are typically satisfied over time, as the customer has access to the product or service during the term of the subscription license and the level of service is consistent during the contract period. Therefore, we recognize revenue for these performance obligations on a straight-line basis, typically over terms of 12 to 36 months . Asset-based revenue is generated through consulting service contracts with our customers of Morningstar Investment Management, Workplace Solutions, and Morningstar Indexes. Our performance obligations under these contracts are satisfied over time as the customer receives continuous access to a service for the contract term. We recognize revenue over the contract term based on the value of assets under management and a tiered fee agreed to with the customer (typically in a range of 30 - 55 basis points of the customer’s average daily portfolio balance). Asset-based arrangements typically have a term of 12 to 36 months . The fees from such arrangements represent variable consideration, and the customer does not make separate purchasing decisions that result in additional performance obligations. Significant changes in the underlying fund assets, or significant disruptions in the market, are evaluated to determine if revisions on estimates of earned asset-based fees for the current quarter are needed. An estimate of variable consideration is included in the initial transaction price only to the extent it is probable that a significant reversal in the amount of revenue recognized will not occur. Estimates of asset-based fees are based on the most recently reported quarter, and, as a result, it is unlikely a significant reversal of revenue would occur. Transaction-based revenue is generated through contracts with our customers for Internet advertising, Morningstar Conferences, and Morningstar Credit Ratings. Our performance obligations for Internet advertising and Morningstar Conferences are satisfied as the service is delivered, and therefore we recognize revenue when the performance obligation is satisfied (as the customer’s advertisements are displayed and at the completion of the Morningstar Conference). Our performance obligations for Morningstar Credit Ratings include the issuance of the rating and may include surveillance services for a period of time as agreed with the customer. We allocate the transaction price to the deliverables based on their relative selling price, which is generally based on the price we charge when the same deliverable is sold separately. Our performance obligation for the issuance of the rating is satisfied when the rating is issued, which is when we recognize the related revenue. Our performance obligations for surveillance services is satisfied over time, as the customer has access to the service during the surveillance period and the level of service is consistent during the contract period. Therefore, we recognize revenue for this performance obligation on a straight-line basis. Our contracts with customers may include multiple performance obligations. For most of these arrangements, we generally allocate revenue to each performance obligation based on its estimated standalone selling price. We generally determine standalone selling prices based on prices charged to customers when the same performance obligation is sold separately. Our contracts with customers may include third-party involvement in providing goods or services to the customer. The inclusion of third-party content does not result in separate performance obligations because is it not delivered separately from the other license obligations. In these arrangements, the customer has contracted to receive a single, bundled solution with third-party and Morningstar content delivered via Morningstar’s subscription services. Revenue and related costs of revenue from third-party content is presented on a gross basis within the condensed consolidated financial statements. We record taxes imposed on revenue-producing transactions (such as sales, use, value-added, and some excise taxes) on a net basis; therefore, we exclude such taxes from revenue in our Consolidated Statements of Income. Deferred revenue represents the portion of licenses or subscriptions billed or collected in advance of the service being provided which we expect to recognize as revenue in future periods. Certain arrangements may have cancellation or refund provisions. If we make a refund, it typically reflects the amount collected from a customer for which we have not yet provided services. The refund therefore results in a reduction of deferred revenue. Sales Commissions. Under prior accounting standards, the Company expensed sales incentive compensation costs, (sales commissions) as incurred. However, upon adopting ASC Topic 606 and ASC 340-40, Other Assets and Deferred Costs - Contracts with Customers , on January 1, 2018 (see Note 18 for additional information), we began capitalizing sales commissions, which are considered directly attributable to obtaining a customer contract. Such costs are capitalized using a portfolio approach that aggregates these costs by legal entity within their geographical regions. Capitalized sales commissions are amortized using the straight-line method over a period that is consistent with the transfer of the products or services to the customer to which the sales commission relates. The period of transfer for each portfolio is the shorter of the weighted-average customer life, or the economic life of the underlying technology that delivers the products or services. As of December 31, 2018, the period of transfer was determined to be two to three years. Discretionary amounts which are added to sales commission payments are expensed as incurred, as they are not considered to be directly attributable to obtaining a customer contract. Advertising Costs. Advertising costs include expenses incurred for various print and Internet ads, search engine fees, and direct mail campaigns. We expense advertising costs as incurred. The table below summarizes our advertising expense for the past three years: (in millions) 2018 2017 2016 Advertising expense $ 6.4 $ 7.0 $ 7.6 Stock-Based Compensation Expense. We account for our stock-based compensation expense in accordance with FASB ASC 718, Compensation—Stock Compensation . Our stock-based compensation expense reflects grants of restricted stock units, restricted stock, performance share awards, market stock units, and stock options. We measure the fair value of our restricted stock units, restricted stock, and performance share awards on the date of grant based on the closing market price of Morningstar's common stock on the day prior to grant. For market stock units, we estimate the fair value of the awards using a Monte Carlo valuation model. For stock options, we estimate the fair value of our stock options on the date of grant using a Black-Scholes option-pricing model. We amortize the fair values to stock-based compensation expense, net of estimated forfeitures, ratably over the vesting period. We estimate expected forfeitures of all employee stock-based awards and recognize compensation cost only for those awards expected to vest. We determine forfeiture rates based on historical experience and adjust the estimated forfeitures to actual forfeiture experience as needed. Liability for Sabbatical Leave. In some of our locations, we offer employees a sabbatical leave. Although the sabbatical policy varies by region, Morningstar's full-time employees are generally eligible for six weeks of paid time off after four years of continuous service. We account for our sabbatical liability in accordance with FASB ASC 710-10-25 , Compensated Absences . We record a liability for employees' sabbatical benefits over the period employees earn the right for sabbatical leave and include this liability in Accrued Compensation in our Consolidated Balance Sheet. Income Taxes. We record deferred income taxes for the temporary differences between the carrying amount of assets and liabilities for financial statement purposes and tax purposes in accordance with FASB ASC 740, Income Taxes (FASB ASC 740). FASB ASC 740 prescribes the minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. It also provides guidance on derecognition, measurement, classification, interest and penalties, accounting in interim periods, and disclosure for uncertain tax positions. We recognize interest and penalties related to unrecognized tax benefits as part of income tax expense in our Consolidated Statements of Income. We classify liabilities related to unrecognized tax benefits as either current or long-term liabilities in our Consolidated Balance Sheet, depending on when we expect to make payment.

Credit Arrangements

Credit Arrangements	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Credit Arrangements	Credit Arrangements In December 2018, we amended our credit agreement to extend the maturity date to December 21, 2020 with no other changes in terms. The credit agreement provides us with a borrowing capacity of up to $300.0 million and provides for issuance of up to $25.0 million of letters of credit under the revolving credit facility. The interest rate applicable to any loan under the credit agreement is, at our option, either: (i) the applicable London interbank offered rate (LIBOR) plus an applicable margin for such loans, which ranges between 1.00% and 1.75% , based on our consolidated leverage ratio or (ii) the lender's base rate plus the applicable margin for such loans, which ranges between 2.00% and 2.75% , based on our consolidated leverage ratio. The credit agreement also contains financial covenants under which we: (i) may not exceed a maximum consolidated leverage ratio of 3.00 to 1.00 and (ii) are required to maintain a minimum consolidated interest coverage ratio of not less than 3.00 to 1.00. We were in compliance with the financial covenants as of December 31, 2018 . We had an outstanding principal balance of $70.0 million at a one-month LIBOR interest rate plus 100 basis points as of December 31, 2018 , leaving borrowing availability of $230.0 million .

Income Per Share

Income Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Income Per Share	Income Per Share The following table shows how we reconcile our net income and the number of shares used in computing basic and diluted income per share: (in millions, except per share amounts) 2018 2017 2016 Basic net income per share attributable to Morningstar, Inc.: Net income attributable to Morningstar, Inc. $ 183.0 $ 136.9 $ 161.0 Weighted average common shares outstanding 42.6 42.7 43.0 Basic net income per share attributable to Morningstar, Inc. $ 4.30 $ 3.21 $ 3.74 Diluted net income per share attributable to Morningstar, Inc.: Net income attributable to Morningstar, Inc. $ 183.0 $ 136.9 $ 161.0 Weighted average common shares outstanding 42.6 42.7 43.0 Net effect of dilutive stock options and restricted stock units 0.4 0.3 0.3 Weighted average common shares outstanding for computing diluted income per share 43.0 43.0 43.3 Diluted net income per share attributable to Morningstar, Inc. $ 4.25 $ 3.18 $ 3.72 The number of weighted average restricted stock units, performance share awards, and market stock units excluded from our calculation of diluted earnings per share, as their inclusion would have been anti-dilutive, was immaterial during the periods presented.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Disaggregation of Revenue The following table presents our revenue disaggregated by revenue type. Sales and usage-based taxes are excluded from revenue. Year ended December 31 (in millions) 2018 2017 2016 License-based $ 751.6 $ 667.7 $ 579.4 Asset-based 200.4 182.2 163.6 Transaction-based 67.9 61.8 55.6 Consolidated revenue $ 1,019.9 $ 911.7 $ 798.6 License-based performance obligations are generally satisfied over time as the customer has access to the product or service during the term of the subscription license and the level of service is consistent during the contract period. License-based agreements typically have a term of 12 to 36 months . License-based revenue is generated from the sale of Morningstar Data, Morningstar Direct, Morningstar Advisor Workstation, Morningstar Enterprise Components, Morningstar Research, PitchBook Data, and other similar products. Asset-based performance obligations are satisfied over time as the customer receives continuous access to a service for the term. Asset-based arrangements typically have a term of 12 to 36 months . The asset-based fees represent variable consideration and the customer does not make separate purchasing decisions that result in additional performance obligations. Significant changes in the underlying fund assets, or significant disruptions in the market, are evaluated to determine if revisions of estimates of earned asset-based fees are needed for the current quarter. An estimate of variable consideration is included in the initial transaction price only to the extent it is probable that a significant reversal in the amount of the revenue recognized will not occur. Estimates of asset-based fees are based on the most recently completed quarter and as a result, it is unlikely a significant reversal of revenue would occur. Asset-based revenue includes Morningstar Investment Management, Workplace Solutions, and Morningstar Indexes. Transaction-based performance obligations are satisfied when the product or service is completed or delivered. Transaction-based revenue includes Morningstar Credit Ratings, Internet Advertising Sales, and Conferences. Morningstar Credit Ratings may include surveillance services, which are recognized over time, as the customer has access to the service during the surveillance period. Contract liabilities Our contract liabilities represent deferred revenue. We record contract liabilities when cash payments are received or due in advance of our performance, including amounts which are refundable. The contract liabilities balance as of December 31, 2018 had a net increase of $24.5 million , primarily driven by cash payments received or due in advance of satisfying our performance obligations. We recognized $163.0 million of revenue in 2018 that was included in the contract liabilities balance as of December 31, 2017 . We expect to recognize revenue related to our contract liabilities for 2019 and subsequent years as follows: (in millions) As of December 31, 2018 2019 $ 388.9 2020 93.7 2021 28.0 2022 11.0 2023 5.4 Thereafter 43.6 $ 570.6 The aggregate amount of revenue we expect to recognize for 2019 and subsequent years is higher than our contract liability balance of $210.0 million as of December 31, 2018 . The difference represents the value of performance obligations for signed contracts where we have not yet begun to satisfy the performance obligations, partially satisfied performance obligations, or have not yet billed the customer. The table above does not include variable consideration for unsatisfied performance obligations related to certain of our licensed-based, asset-based, and transaction-based contracts as of December 31, 2018 . We are applying the optional exemption as the variable consideration relates to these unsatisfied performance obligations being fulfilled as a series. The performance obligations related to these contracts are expected to be satisfied over the next 12 to 36 months as services are provided to the client. For licensed-based contracts, the consideration received for services performed is based on future user count, which will be known at the time the services are performed. The variable consideration for this revenue can be affected by the number of user licenses. For asset-based contracts, the consideration received for services performed is based on future asset values, which will be known at the time the services are performed. The variable consideration for this revenue can be affected by changes in the underlying value of fund assets due to client redemptions, additional investments, or significant movements in the market. For transaction-based contracts such as Internet advertising, the consideration received for services performed is based on the number of impressions, which will be known once impressions are created. The variable consideration for this revenue can be affected by the timing and quantity of impressions in any given period. The table above also does not include revenue for unsatisfied performance obligations related to certain of our license-based and transaction-based contracts as of December 31, 2018 . We are applying the optional exemption as the performance obligations for such contracts have an expected duration of one year or less. For certain license-based contracts, the remaining performance obligation is expected to be less than one year based on the corresponding subscription terms. For transaction-based contracts, such as new credit rating issuances and the Morningstar conference, the related performance obligations are expected to be satisfied within the next twelve months. Contract Assets Our contract assets represent accounts receivable, less allowance for doubtful accounts and deferred commissions. We did not record any impairment losses on receivables or deferred commissions in 2018 . The following table summarizes our contract assets balance: (in millions) As of December 31, 2018 As of December 31, 2017 Accounts receivable, less allowance for doubtful accounts $ 172.2 $ 148.2 Deferred commissions 14.8 — Deferred commissions, non-current 10.3 — Total contract assets $ 197.3 $ 148.2 The following table shows the change in our deferred commissions balance from January 1, 2018 to December 31, 2018 : (in millions) Balance as of January 1, 2018 $ 22.7 Commissions earned and capitalized 19.4 Amortization of capitalized amounts (17.0 ) Balance as of December 31, 2018 $ 25.1

Segment and Geographical Area I

Segment and Geographical Area Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment and Geographical Area Information	Segment and Geographical Area Information Segment Information We report our results in a single reportable segment, which reflects how our chief operating decision maker allocates resources and evaluates our financial results. Because we have a single reportable segment, all required financial segment information can be found directly in the Consolidated Financial Statements. The accounting policies for our reportable segment are the same as those described in Note 2 . We evaluate the performance of our reporting segment based on revenue and operating income. Geographical Area Information The tables below summarize our revenue and long-lived assets by geographical area: External revenue by geographical area Year ended December 31 (in millions) 2018 2017 2016 United States $ 764.2 $ 687.0 $ 590.5 United Kingdom 72.4 64.7 61.1 Continental Europe 81.2 69.9 62.6 Australia 40.9 34.6 32.2 Canada 30.7 29.4 28.2 Asia 24.5 21.2 20.0 Other 6.0 4.9 4.0 Total International 255.7 224.7 208.1 Consolidated revenue $ 1,019.9 $ 911.7 $ 798.6 Long-lived assets by geographical area As of December 31 (in millions) 2018 2017 United States $ 126.4 $ 131.9 United Kingdom 3.8 6.0 Continental Europe 1.3 1.7 Australia 5.0 2.3 Canada 0.3 0.2 Asia 6.5 5.2 Other 0.2 0.1 Total International 17.1 15.5 Consolidated property, equipment, and capitalized software, net $ 143.5 $ 147.4 The long-lived asset by geographical area does not include deferred commissions, non-current as the balance is not significant.

Investments and Fair Value Meas

Investments and Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Investments and Fair Value Measurements	Investments and Fair Value Measurements We classify our investments into three categories: available-for-sale, held-to-maturity, and trading. Our investment portfolio consists of stocks, bonds, options, mutual funds, money market funds, or exchange-traded products that replicate the model portfolios and strategies created by Morningstar. These investment accounts may also include exchange-traded products where Morningstar is an index provider. We classify our investment portfolio as shown below: As of December 31 (in millions) 2018 2017 Available-for-sale $ 20.1 $ 21.5 Held-to-maturity 2.5 21.9 Trading securities 4.0 1.7 Total $ 26.6 $ 45.1 The following table shows the cost, unrealized gains (losses), and fair values related to investments classified as available-for-sale and held-to-maturity: As of December 31, 2018 As of December 31, 2017 (in millions) Cost Unrealized Gain Unrealized Loss Fair Value Cost Unrealized Gain Unrealized Loss Fair Value Available-for-sale: Equity securities and exchange-traded funds $ 17.9 $ 1.2 $ (1.8 ) $ 17.3 $ 17.1 $ 2.4 $ (0.6 ) $ 18.9 Mutual funds 3.0 — (0.2 ) 2.8 2.4 0.2 — 2.6 Total $ 20.9 $ 1.2 $ (2.0 ) $ 20.1 $ 19.5 $ 2.6 $ (0.6 ) $ 21.5 Held-to-maturity: Certificates of deposit $ 2.5 $ — $ — $ 2.5 $ 19.9 $ — $ — $ 19.9 Convertible note — — — — 2.0 — — 2.0 Total $ 2.5 $ — $ — $ 2.5 $ 21.9 $ — $ — $ 21.9 As of December 31, 2018 and December 31, 2017 , investments with unrealized losses for greater than a 12-month period were not material to the Consolidated Balance Sheets and were not deemed to have other than temporary declines in value. The table below shows the cost and fair value of investments classified as available-for-sale and held-to-maturity based on their contractual maturities as of December 31, 2018 and December 31, 2017 . As of December 31, 2018 As of December 31, 2017 (in millions) Cost Fair Value Cost Fair Value Available-for-sale: Equity securities, exchange-traded funds, and mutual funds $ 20.9 $ 20.1 $ 19.5 $ 21.5 Total $ 20.9 $ 20.1 $ 19.5 $ 21.5 Held-to-maturity: Due in one year or less $ 2.3 $ 2.3 $ 19.7 $ 19.7 Due in one to three years 0.2 0.2 2.2 2.2 Total $ 2.5 $ 2.5 $ 21.9 $ 21.9 The following table shows the realized gains and losses arising from sales of our investments classified as available-for-sale recorded in our Consolidated Statements of Income: (in millions) 2018 2017 2016 Realized gains $ 1.8 $ 3.4 $ 1.6 Realized losses (0.8 ) (0.2 ) (1.0 ) Realized gains, net $ 1.0 $ 3.2 $ 0.6 We determine realized gains and losses using the specific identification method. The following table shows the net unrealized gains (losses) on trading securities as recorded in our Consolidated Statements of Income: (in millions) 2018 2017 2016 Unrealized gains (losses), net $ (0.2 ) $ 0.1 $ — The table below shows the fair value of our assets subject to fair value measurements that are measured at fair value on a recurring basis using a fair value hierarchy: Level 1: Valuations based on quoted prices in active markets for identical assets or liabilities that we have the ability to access. Level 2: Valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3: Valuations based on inputs that are unobservable and significant to the overall fair value measurement. Fair Value Fair Value Measurements as of December 31, 2018 as of Using Fair Value Hierarchy (in millions) December 31, 2018 Level 1 Level 2 Level 3 Available-for-sale investments Equity securities and exchange-traded funds $ 17.3 $ 17.3 $ — $ — Mutual funds 2.8 2.8 — — Trading securities 4.0 4.0 — — Cash equivalents 0.1 0.1 — — Total $ 24.2 $ 24.2 $ — $ — Fair Value Fair Value Measurements as of December 31, 2017 as of Using Fair Value Hierarchy (in millions) December 31, 2017 Level 1 Level 2 Level 3 Available-for-sale investments Equity securities and exchange-traded funds $ 18.9 $ 18.9 $ — $ — Mutual funds 2.6 2.6 — — Trading securities 1.7 1.7 — — Cash equivalents 0.5 0.5 — — Total $ 23.7 $ 23.7 $ — $ — Based on our analysis of the nature and risks of our investments in equity securities and mutual funds, we have determined that presenting each of these investment categories in the aggregate is appropriate. We measure the fair value of money market funds, mutual funds, equity securities, and exchange-traded funds based on quoted prices in active markets for identical assets or liabilities. We did not hold any securities categorized as Level 2 or Level 3 as of December 31, 2018 and December 31, 2017 .

Acquisitions, Goodwill, and Oth

Acquisitions, Goodwill, and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Acquisitions, Goodwill, and Other Intangible Assets [Abstract]
Acquisitions, Goodwill, and Other Intangible Assets	Acquisitions, Goodwill, and Other Intangible Assets 2018 Acquisitions We did not complete any significant acquisitions in 2018. 2017 Acquisitions We did not complete any significant acquisitions in 2017. 2016 Acquisitions Increased Ownership Interest in PitchBook Data, Inc. (PitchBook) In December 2016, we acquired an additional 78% interest in PitchBook Data, Inc. (PitchBook), increasing our ownership to 100% from 22% . PitchBook delivers data, research, and technology covering the private capital markets, including venture capital, private equity, and mergers and acquisitions. We began consolidating the financial results of this acquisition in our Consolidated Financial Statements on December 1, 2016. PitchBook contributed $4.1 million of revenue and $7.5 million of operating expense during the one-month period that PitchBook was included in our consolidated results for 2016. PitchBook's total estimated fair value of $235.1 million as of the acquisition date includes $188.2 million in cash paid to acquire the remaining 78% interest in PitchBook as well as a $46.9 million fair value related to our previous 22% ownership interest. The book value of this ownership immediately prior to the acquisition date was $9.8 million , and we recorded a noncash holding gain of $37.1 million for the difference between the fair value and the book value of our previously held investment. We used the income approach and a discounted cash flow analysis of PitchBook’s projected revenue, operating expense, and other amounts to arrive at the estimated fair value. The gain is classified as "Holding gain upon acquisition of additional ownership of equity-method investments" in our Consolidated Statement of Income for the year ended December 31, 2016. The transaction has been accounted for using the acquisition method of accounting, which requires that assets acquired and liabilities assumed be recognized at their fair values as of the acquisition date. Adjustments recorded in the measurement period to the purchase price allocation were not significant. The following table summarizes our allocation of the estimated fair values of the assets acquired and liabilities assumed at the date of acquisition: (in millions) Cash and cash equivalents $ 12.4 Accounts receivable 10.8 Other current and non-current assets 3.2 Intangible assets 60.7 Goodwill 192.0 Deferred revenue (22.0 ) Deferred tax liability, net (12.3 ) Other current and non-current liabilities (9.7 ) Total fair value of PitchBook $ 235.1 Accounts receivable acquired were recorded at gross contractual amounts receivable, which approximates fair value. The allocation includes $60.7 million of acquired intangible assets, as follows: (in millions) Weighted Average Useful Life (years) Customer-related assets $ 17.1 10 Technology-based assets 40.8 5 Intellectual property (trademarks and trade names) 2.8 4 Total intangible assets $ 60.7 6 We recognized a net deferred tax liability of $12.3 million mainly because the amortization expense related to certain intangible assets is not deductible for income tax purposes. Goodwill of $192.0 million represents the excess over the fair value of the net tangible and intangible assets acquired with this acquisition. We paid this premium for a number of reasons, including the opportunity to offer comprehensive data coverage across the full life cycle of private market transactions. The goodwill is not deductible for income tax purposes. Unaudited Pro Forma Information for PitchBook Acquisition The following unaudited pro forma information presents a summary of our Consolidated Statements of Income for the years ended December 31, 2016 and 2015, as if we had completed the PitchBook acquisition as of January 1, 2015. This unaudited pro forma information is presented for illustrative purposes and is not intended to represent or be indicative of the actual results of operations of the combined company that would have been achieved had the acquisition occurred at the beginning of the earliest period presented, nor is it intended to represent or be indicative of future results of operations. In calculating the pro forma information below, we included an estimate of amortization expense related to the intangible assets acquired, stock-based compensation expense related to the PitchBook bonus plan (see Note 13 for additional information), and interest expense incurred on the long-term debt. The 2016 pro forma net income excludes the $37.1 million noncash holding gain generated in connection with the transaction. Unaudited Pro Forma Financial Information (in millions) 2016 2015 Revenue $ 834.1 $ 813.3 Operating income 157.7 170.0 Net income 105.5 117.1 Basic net income per share attributable to Morningstar, Inc. $ 2.45 $ 2.65 Diluted net income per share attributable to Morningstar, Inc. $ 2.44 $ 2.65 RequiSight, LLC (RightPond) On March 31, 2016, we acquired RequiSight, LLC, which does business as RightPond, a provider of business intelligence data and analytics on defined-contribution and defined-benefit plans for financial services firms. We began consolidating the financial results of RightPond in our Consolidated Financial Statements on March 31, 2016. InvestSoft Technology, Inc. (InvestSoft) On May 31, 2016, we acquired InvestSoft Technology, Inc. (InvestSoft), a provider of fixed-income analytics. We began consolidating the financial results of InvestSoft in our Consolidated Financial Statements on May 31, 2016. Goodwill The following table shows the changes in our goodwill balances from January 1, 2017 to December 31, 2018 : (in millions) Balance as of January 1, 2017 $ 556.8 Divestiture of HelloWallet (See Note 9) (2.4 ) Foreign currency translation and adjustments to purchase price allocation 10.5 Balance as of December 31, 2017 $ 564.9 Other, primarily foreign currency translation (8.2 ) Balance as of December 31, 2018 $ 556.7 We did not record any impairment losses in 2018 , 2017 , or 2016 as the estimated fair value of our reporting unit exceeded its carrying value. We perform our annual impairment testing during the fourth quarter of each year. Intangible Assets The following table summarizes our intangible assets: As of December 31, 2018 As of December 31, 2017 (in millions) Gross Accumulated Amortization Net Weighted Average Useful Life (years) Gross Accumulated Amortization Net Weighted Average Useful Life (years) Intellectual property $ 30.8 $ (29.2 ) $ 1.6 9 $ 31.5 $ (28.9 ) $ 2.6 9 Customer-related assets 153.0 (111.7 ) 41.3 12 156.6 (108.1 ) 48.5 12 Supplier relationships 0.2 (0.1 ) 0.1 20 0.2 (0.1 ) 0.1 20 Technology-based assets 126.9 (96.3 ) 30.6 7 127.9 (84.2 ) 43.7 7 Non-competition agreements 2.4 (2.1 ) 0.3 5 2.5 (2.0 ) 0.5 5 Total intangible assets $ 313.3 $ (239.4 ) $ 73.9 10 $ 318.7 $ (223.3 ) $ 95.4 10 The following table summarizes our amortization expense related to intangible assets: (in millions) 2018 2017 2016 Amortization expense $ 20.7 $ 23.6 $ 19.4 We did not record any impairment losses involving intangible assets in 2018 , 2017 , or 2016. We amortize intangible assets using the straight-line method over their expected economic useful lives. Based on acquisitions and divestitures completed through December 31, 2018 , we expect intangible amortization expense for 2019 and subsequent years to be as follows: (in millions) 2019 $ 19.2 2020 16.2 2021 12.9 2022 5.0 2023 5.0 Thereafter 15.6 Our estimates of future amortization expense for intangible assets may be affected by additional acquisitions, divestitures, changes in the estimated average useful life, and foreign currency translation.

Divestitures

Divestitures	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Divestitures	Divestiture 2018 Divestitures In January 2018, we sold our 15(c) board consulting services product line for $10.5 million and recorded a gain of $10.5 million on the sale. 2017 Divestitures On June 30, 2017, we sold HelloWallet to KeyBank National Association, a bank-based financial services company. We recorded a noncash gain on the sale of $16.7 million . This gain mainly represents the sale proceeds of $23.7 million less $2.4 million of goodwill and the write-off of the remaining net book value of the acquired intangible assets. As some aspects of HelloWallet had been integrated into Morningstar's single reporting unit, the goodwill attributable to this transaction was calculated using a relative fair value allocation method. The sale of HelloWallet did not meet the criteria to be classified as a discontinued operation because the divestiture did not represent a strategic shift that has, or will have, a major effect on our operations and financial results. The following table summarizes the amounts included in the gain on sale of business for the year ended December 31, 2017: Year ended December 31 (in millions) 2017 Proceeds received $ 23.7 Intangibles and internally developed software (4.5 ) Goodwill (2.4 ) Other assets and liabilities (0.1 ) Total gain on sale of business $ 16.7

Investments in Unconsolidated E

Investments in Unconsolidated Entities	12 Months Ended
	Dec. 31, 2018
Investments in Unconsolidated Entities [Abstract]
Investments in Unconsolidated Entities	Investments in Unconsolidated Entities Our investments in unconsolidated entities consist primarily of the following: As of December 31 (in millions) 2018 2017 Investment in MJKK $ 23.9 $ 26.4 Investment in Sustainalytics 25.7 20.7 Other-equity method investments 10.3 12.6 Investments accounted for using the cost method 3.2 2.3 Total investments in unconsolidated entities $ 63.1 $ 62.0 Morningstar Japan K.K. Morningstar Japan K.K. (MJKK) develops and markets financial information products and services customized for the Japanese market. MJKK’s shares are traded on the Tokyo Stock Exchange under the ticker 47650. We account for our investment in MJKK using the equity method. The following table summarizes our ownership percentage in MJKK and the market value of this investment based on MJKK’s publicly quoted share price: As of December 31 2018 2017 Morningstar’s approximate ownership of MJKK 30 % 34 % Approximate market value of Morningstar’s ownership in MJKK: Japanese yen (¥ in millions) ¥ 7,525.4 ¥ 10,649.6 Equivalent U.S. dollars ($ in millions) $ 68.4 $ 94.6 Sustainalytics Holding B.V. In July 2017, we acquired a minority stake in Sustainalytics Holding B.V. (Sustainalytics), which is an independent environmental, social, and governance and corporate governance research, ratings, and analysis firm supporting investors around the world with the development and implementation of responsible investment strategies. Our ownership in Sustainalytics was 44% as of December 31, 2018 and 40% as of December 31, 2017 .

Property, Equipment, and Capita

Property, Equipment, and Capitalized Software	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Equipment, and Capitalized Software	Property, Equipment, and Capitalized Software The following table shows our property, equipment, and capitalized software summarized by major category: As of December 31 (in millions) 2018 2017 Capitalized software $ 294.8 $ 239.2 Capitalized equipment 83.5 81.6 Furniture and fixtures 29.6 27.6 Leasehold improvements 77.3 72.5 Telephone equipment 2.1 2.3 Construction in progress 7.9 8.9 Property, equipment, and capitalized software, at cost 495.2 432.1 Less accumulated depreciation (351.7 ) (284.7 ) Property, equipment, and capitalized software, net $ 143.5 $ 147.4 The following table summarizes our depreciation expense: (in millions) 2018 2017 2016 Depreciation expense $ 76.0 $ 67.6 $ 51.3 Depreciation expense in 2017 includes a $4.1 million impairment charge for certain software licenses due to a shift toward a cloud-based strategy.

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2018
Leases, Operating [Abstract]
Operating Leases	Operating Leases The following table shows our minimum future rental commitments due in each of the next five years and thereafter for all non-cancelable operating leases, consisting primarily of commitments for office space: Minimum Future Rental Commitments (in millions) 2019 $ 34.4 2020 36.0 2021 32.2 2022 20.8 2023 15.1 Thereafter 47.7 Total $ 186.2 The following table summarizes our rent expense, including taxes, insurance, and related operating costs: (in millions) 2018 2017 2016 Rent expense $ 32.5 $ 30.3 $ 26.3 Deferred rent includes build-out and rent abatement allowances received, which are amortized over the remaining portion of the original term of the lease as a reduction in office lease expense. We include deferred rent, as appropriate, in “Accounts payable and accrued liabilities” and “Deferred rent, noncurrent” on our Consolidated Balance Sheets. As of December 31 (in millions) 2018 2017 Deferred rent $ 28.6 $ 31.2

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Stock-Based Compensation Plans Our shareholders approved the Morningstar 2011 Stock Incentive Plan (the 2011 Plan) on May 17, 2011. As of that date, we stopped granting awards under the Morningstar 2004 Stock Incentive Plan (the 2004 Plan). The 2004 Plan amended and restated the Morningstar 1993 Stock Option Plan, the Morningstar 2000 Stock Option Plan, and the Morningstar 2001 Stock Option Plan. The 2011 Plan provides for a variety of stock-based awards, including, among other things, restricted stock units, restricted stock, performance share awards, market stock units, and stock options. We granted restricted stock units, restricted stock, and stock options under the 2004 Plan. All of our employees and our non-employee directors are eligible for awards under the 2011 Plan. Grants awarded under the 2011 Plan or the 2004 Plan that are forfeited, canceled, settled, or otherwise terminated without a distribution of shares, or shares withheld by us in connection with the exercise of options, will be available for awards under the 2011 Plan. For any shares subject to awards that are withheld by us in connection with the payment of any required income tax withholding, the 2011 Plan provides for the ability to have these shares become available for new awards, but this feature of the 2011 plan has not been implemented. The following table summarizes the number of shares available for future grants under our 2011 Plan: As of December 31 (in millions) 2018 Shares available for future grants 3.1 Accounting for Stock-Based Compensation Awards The following table summarizes our stock-based compensation expense and the related income tax benefit we recorded in the past three years: Year ended December 31 (in millions) 2018 2017 2016 Restricted stock units $ 19.8 $ 16.5 $ 14.6 Performance share awards 10.2 7.1 (0.1 ) Market stock units 1.7 0.5 — Total stock-based compensation expense $ 31.7 $ 24.1 $ 14.5 Income tax benefit related to the stock-based compensation expense $ 7.0 $ 7.8 $ 4.3 The following table summarizes the stock-based compensation expense included in each of our operating expense categories for the past three years: Year ended December 31 (in millions) 2018 2017 2016 Cost of revenue $ 11.7 $ 9.6 $ 7.5 Sales and marketing 3.5 3.0 1.9 General and administrative 16.5 11.5 5.1 Total stock-based compensation expense $ 31.7 $ 24.1 $ 14.5 The following table summarizes the amount of unrecognized stock-based compensation expense as of December 31, 2018 and the expected number of months over which the expense will be recognized: Unrecognized stock-based compensation expense (in millions) Weighted average expected amortization period (months) Restricted stock units $ 36.9 33 Market stock units 5.2 28 Total unrecognized stock-based compensation expense $ 42.1 32 In accordance with FASB ASC 718, Compensation—Stock Compensation , we estimate forfeitures of employee stock-based awards and recognize compensation cost only for those awards expected to vest. Restricted Stock Units Restricted stock units represent the right to receive a share of Morningstar common stock when that unit vests. Restricted stock units granted to employees vest ratably over a four -year period. Restricted stock units granted to non-employee directors vest ratably over a three -year period. We measure the fair value of our restricted stock units on the date of grant based on the closing market price of the underlying common stock on the day prior to grant. We amortize that value to stock-based compensation expense, net of estimated forfeitures, ratably over the vesting period. The following table summarizes restricted stock unit activity during the past three years: Restricted Stock Units (RSUs) Unvested Vested but Deferred Total Weighted Average Grant Date Value per RSU RSUs Outstanding - December 31, 2015 572,526 14,924 587,450 $ 72.14 Granted 241,609 — 241,609 77.82 Dividend equivalents 370 136 506 56.52 Vested (225,590 ) — (225,590 ) 69.39 Issued — (5,312 ) (5,312 ) 44.47 Forfeited (47,670 ) — (47,670 ) 74.45 RSUs Outstanding - December 31, 2016 541,245 9,748 550,993 $ 75.77 Granted 331,470 — 331,470 78.33 Dividend equivalents — 78 78 60.99 Vested (212,005 ) — (212,005 ) 75.38 Issued — (6,547 ) (6,547 ) 49.40 Forfeited (55,831 ) — (55,831 ) 76.49 RSUs Outstanding - December 31, 2017 604,879 3,279 608,158 $ 77.52 Granted 243,614 — 243,614 108.60 Dividend equivalents — 16 16 73.28 Vested (279,774 ) — (279,774 ) 80.68 Issued — (3,295 ) (3,295 ) 73.28 Forfeited (41,254 ) — (41,254 ) 86.47 RSUs Outstanding - December 31, 2018 527,465 — 527,465 $ 89.53 Performance Share Awards In March 2016, executive officers, other than Joe Mansueto, and certain other employees, were granted performance share awards. These awards entitle the holder to a number of shares of Morningstar common stock equal to the number of notional performance shares that become vested. Each award specifies a number of performance shares that will vest if pre-established target performance goals are attained. The number of performance shares that actually vest may be more or less than the specified number of performance shares to the extent Morningstar exceeds or fails to achieve, respectively, the target performance goals over a three -year performance period. We base the grant date fair value for these awards on the closing market price of the underlying common stock on the day prior to the grant date. We amortize that value to stock-based compensation expense ratably over the vesting period based on the satisfaction of the performance condition that is most likely to be satisfied over the three -year performance period. The table below shows target performance share awards granted and shares that would be issued at current performance levels for performance share awards granted as of December 31, 2018 : As of December 31, 2018 Target performance share awards granted 41,439 Weighted average fair value per award $ 81.71 Number of shares that would be issued based on current performance levels — Unamortized expense, based on current performance levels (in millions) $ — Market Stock Units In May and November 2017 and 2018, executive officers, other than Joe Mansueto, and certain other employees, were granted market stock units. These market stock units represent the right to receive a target number of shares that will vest at the end of a three-year performance period depending on the company’s total shareholder return over that three-year period. We measure the fair value of our market stock units on the date of grant using a Monte Carlo valuation model. We amortize that value to stock-based compensation expense ratably over the vesting period. We used the following assumptions to estimate the fair value of our market stock units during 2017 and 2018 : Assumptions for Monte Carlo Valuation Model Grant Date Expected volatility Dividend yield Risk-free interest rate May 15, 2017 17.4 % 1.20 % 1.49 % November 15, 2017 17.7 % 1.04 % 1.79 % May 15, 2018 17.4 % 0.89 % 2.70 % November 15, 2018 19.6 % 0.83 % 2.92 % The table below shows market stock units granted and target market stock units outstanding as of December 31, 2018 : As of December 31, 2018 Market stock units granted 84,153 Weighted average fair value per award $ 89.58 Number of target market stock units outstanding 81,274 Unamortized expense, based on current performance levels (in millions) $ 5.2 PitchBook Bonus Plan In connection with our acquisition of PitchBook, we adopted a management bonus sub-plan under the 2011 Plan for certain employees of PitchBook (the PitchBook Plan). Pursuant to the terms of the PitchBook Plan, awards having an aggregate target value equal to $30.0 million will be available for issuance with annual grants of $7.5 million for 2017, $7.5 million in 2018, and $15.0 million in 2019. Subject to the satisfaction of certain conditions, we have agreed to renew the PitchBook Plan for the 2020-2022 period. Pursuant to the terms of this renewal, awards having an aggregate target value equal to $30.0 million will be available for issuance with annual grants of $7.5 million for 2020, $7.5 million in 2021, and $15.0 million in 2022 . Each grant will consist of performance-based share unit awards which will vest over a one -year period and will be measured primarily based on the achievement of certain annual revenue targets specifically related to PitchBook’s business. Upon achievement of these targets, earned performance units will be settled in shares of our common stock on a one -for-one basis. If PitchBook exceeds certain performance conditions, the PitchBook Plan participants will receive payment for performance units in excess of the aggregate target values described above. If PitchBook fails to meet threshold performance conditions, the PitchBook Plan participants will not be entitled to receive payment for any performance units. The table below shows target performance share awards granted and shares that will be issued based on final performance levels for performance share awards granted as of December 31, 2018 : As of December 31, 2018 Target performance share awards granted 77,716 Weighted average fair value per award $ 95.53 Number of shares that will be issued based on final 2018 performance levels 106,854 Unamortized expense, based on current performance levels (in millions) $ — Stock Options Stock options granted to employees vest ratably over a four -year period. Grants to our non-employee directors vest ratably over a three -year period. All grants expire 10 years after the date of grant. In May 2011, we granted 86,106 stock options under the 2004 Stock Incentive Plan. In November 2011, we granted 6,095 stock options under the 2011 Plan. All options granted in 2011 have an exercise price equal to the fair market value on the grant date. We estimated the fair value of the options on the grant date using a Black-Scholes option-pricing model. The weighted average fair value of options granted during 2011 was $23.81 per share, based on the following assumptions: Assumptions for Black-Scholes Option Pricing Model Expected life (years) 7.4 Volatility factor 35.1 % Dividend yield 0.35 % Interest rate 2.87 % The following table summarizes stock option activity in the past three years for our various stock option grants: 2018 2017 2016 Option Grants Underlying Shares Weighted Average Exercise Price Underlying Shares Weighted Average Exercise Price Underlying Shares Weighted Average Exercise Price Options outstanding—beginning of year 41,685 $ 57.28 46,001 $ 57.28 52,096 $ 57.52 Granted — — — — — — Canceled — — — — — — Exercised (1,000 ) 57.28 (4,316 ) 57.28 (6,095 ) 59.35 Options outstanding—end of year 40,685 $ 57.28 41,685 $ 57.28 46,001 $ 57.28 Options exercisable—end of year 40,685 $ 57.28 41,685 $ 57.28 46,001 $ 57.28 The following table summarizes the total intrinsic value (difference between the market value of our stock on the date of exercise and the exercise price of the option) of options exercised: (in millions) 2018 2017 2016 Intrinsic value of options exercised $ 0.1 $ 0.1 $ 0.1 The table below shows additional information for options outstanding and exercisable as of December 31, 2018 : Options Outstanding Options Exercisable Range of Exercise Prices Number of Options Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Aggregate Intrinsic Value (in millions) Exercisable Shares Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Aggregate Intrinsic Value (in millions) $57.28 40,685 2.37 $ 57.28 $ 2.1 40,685 2.37 $ 57.28 $ 2.1 Vested or Expected to Vest $57.28 40,685 2.37 $ 57.28 $ 2.1 The aggregate intrinsic value in the table above represents the total pretax intrinsic value all option holders would have received if they had exercised all outstanding options on December 31, 2018 . The intrinsic value is based on our closing stock price of $109.84 on December 31, 2018 .

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2018
Defined Contribution Plan [Abstract]
Defined Contribution Plan	Defined-Contribution Plan We sponsor a defined-contribution 401(k) plan, which allows our U.S.-based employees to voluntarily contribute pretax dollars up to a maximum amount allowable by the U.S. Internal Revenue Service. In 2018 , 2017 , and 2016 , we made matching contributions to our 401(k) plan in the U.S. in an amount equal to 75 cents for every dollar of an employee's contribution, up to a maximum of 7% of the employee's compensation in the pay period. The following table summarizes our matching contributions: (in millions) 2018 2017 2016 401(k) matching contributions $ 11.0 $ 10.4 $ 9.0

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income Tax Expense and Effective Tax Rate The following table shows our income tax expense and our effective tax rate for the years ended December 31, 2018 , 2017 , and 2016 : (in millions) 2018 2017 2016 Income before income taxes and equity in net loss of unconsolidated entities $ 232.9 $ 181.1 $ 224.9 Equity in net loss of unconsolidated entities (2.1 ) (1.3 ) (0.2 ) Total $ 230.8 $ 179.8 $ 224.7 Income tax expense $ 47.8 $ 42.9 $ 63.7 Effective tax rate 20.7 % 23.9 % 28.3 % On December 22, 2017, the President of the United States signed into law the Tax Reform Act. The legislation significantly changed U.S. tax law by, among other things, lowering corporate income tax rates, changing to a territorial tax system and imposing a transitional tax on deemed repatriated earnings of foreign subsidiaries. The Tax Reform Act permanently reduces the U.S. corporate income tax rate from a maximum of 35% to a flat 21% rate, effective from January 1, 2018. In our consolidated financial statements for the year ended December 31, 2017, we recognized a $10.6 million discrete net tax benefit. SAB 118 allowed for the recording of provisional amounts which were primarily comprised of the following: • A $14.7 million deferred tax benefit from revaluing our net U.S. deferred tax liabilities at December 31, 2017 to reflect the new U.S. corporate tax rate. • A tax expense of $7.5 million for the transitional tax liability on deemed repatriated earnings of foreign subsidiaries. This tax expense was offset by a tax benefit of a $6.4 million reduction of a deferred tax liability previously recorded for our foreign equity method investments. • A tax expense of $3.0 million related to changes in our indefinite reinvestment assertion. We recorded deferred taxes in the amount of $3.0 million for foreign withholding taxes that would be due upon remittance of dividends from certain of our foreign affiliates. In the fourth quarter of 2018, we completed our accounting for the Tax Reform Act within the one-year measurement period required by SAB 118. Changes from our provisional estimates recorded in 2017 were not significant but were favorable and resulted in an additional decrease in our tax expense recorded in our Consolidated Statements of Income in 2018. In addition to the reduction of the U.S. corporate income tax rate to a flat 21% rate discussed above, we are subject to the following provisions of the Tax Reform Act effective from January 1, 2018: • impose a new minimum tax on certain non-U.S. earnings, irrespective of the territorial system of taxation, and generally allows for the repatriation of future earnings of foreign subsidiaries without incurring additional U.S. taxes by transitioning to a territorial system of taxation (Global Intangible Low-Taxed Income or GILTI Tax); • eliminate tax incentives for domestic production activities in the United States (the Section 199 Deduction) but create an incentive for U.S. companies to sell, lease or license goods and services abroad by allowing for a new deduction for Foreign-Derived Intangible Income (the FDII Deduction); • subject certain payments made by a U.S. company to related foreign companies to certain minimum taxes (Base Erosion Anti-Abuse Tax or BEAT); • disallow net business interest deductions in excess of 30% of adjusted U.S. taxable income without regard to interest expense, interest income, taxes, net operating losses, depreciation and amortization for years beginning before January 1, 2022, (generally, EBITDA) and taxable income without regard to interest and taxes (EBIT) thereafter with indefinite carryforwards of excess interest expense (the 163(j) Interest Limitation); • reduces deductions with respect to certain employee fringe benefits and reduces deductions for compensation paid to specified executive officers. With respect to the above provisions, our effective tax rate in the 12 months ended December 31, 2018 is favorably impacted as a result of the federal statutory income tax rate change from 35% of 21% and the tax benefits of the FDII Deduction. The impact of these favorable provisions is offset by the loss of tax benefits eliminated with the repeal of the Section 199 Deduction, the incremental tax expense attributable to GILTI Tax and, to a lesser extent, the incremental tax expense for disallowed deductions for employee fringe benefits and executive compensation. Our effective tax rate in the 12 months ended December 31, 2018 was not impacted by BEAT or the 163(j) Interest Limitation. With respect to the GILTI Tax, we are required to make an accounting policy election of either (1) treating taxes due on U.S. inclusions in taxable income related to the GILTI Tax as a current period expense when incurred or (2) factoring such amounts into the measurement of our deferred taxes. We have elected to account for GILTI Tax as a period expense in the period in which it is incurred, and, therefore, have not provided for any deferred tax impact of GILTI Tax in our Consolidated Statements of Income or Consolidated Balance Sheets. The amount of accumulated undistributed earnings of our foreign subsidiaries was approximately $209.2 million as of December 31, 2018. In February 2019, we repatriated approximately $45.8 million of these foreign earnings back to the U.S. Otherwise, we generally consider our U.S. directly-owned foreign subsidiary earnings to be permanently reinvested. We have not recorded deferred income taxes on the $209.2 million primarily because most of these earnings were previously subject to the one-time deemed mandatory repatriation tax under that Tax Reform Act, which we recorded in 2017 as an expense in our Consolidated Statements of Income. Certain foreign affiliate parent companies are not indefinitely reinvested, and thus, we maintain a deferred tax liability for foreign withholding taxes. The following table reconciles our income tax expense at the U.S. federal income tax rate to income tax expense as recorded: 2018 2017 2016 (in millions, except percentages) Amount % Amount % Amount % Income tax expense at U.S. federal rate $ 48.5 21.0 % $ 63.0 35.0 % $ 78.6 35.0 % State income taxes, net of federal income tax benefit 7.4 3.2 3.0 1.7 4.5 2.0 Change in U.S. tax rate (0.6 ) (0.3 ) (14.7 ) (8.2 ) — — Deemed mandatory repatriation (1.2 ) (0.5 ) 7.5 4.2 — — Reduction of deferred tax liabilities for foreign equity method investments (0.5 ) (0.2 ) (6.4 ) (3.6 ) — — Withholding tax - repatriation — — 3.0 1.7 — — Stock-based compensation activity (2.6 ) (1.1 ) 0.3 0.2 (0.6 ) (0.3 ) Equity in net income of unconsolidated subsidiaries (including holding gains upon acquisition) 1.0 0.4 1.2 0.7 (12.1 ) (5.4 ) Book gain over tax gain on sale of HelloWallet — — (6.8 ) (3.8 ) — — Net change in valuation allowance related to non-U.S. deferred tax assets, primarily net operating losses (0.2 ) (0.1 ) 0.1 0.1 (0.1 ) — Difference between U.S. federal statutory and foreign tax rates 0.2 0.1 (5.2 ) (2.9 ) (5.3 ) (2.4 ) Change in unrecognized tax benefits 1.0 0.4 1.2 0.7 2.6 1.2 Credits and incentives (3.6 ) (1.6 ) (3.7 ) (2.1 ) (3.7 ) (1.6 ) GILTI tax 1.4 0.6 — — — — FDII deduction (5.1 ) (2.2 ) — — — — Other - net 2.1 0.9 0.4 0.2 (0.2 ) (0.1 ) Total income tax expense $ 47.8 20.7 % $ 42.9 23.9 % $ 63.7 28.3 % Income tax expense consists of the following: Year ended December 31 (in millions) 2018 2017 2016 Current tax expense: U.S. Federal $ 31.0 $ 40.3 $ 42.8 State 11.1 6.6 6.5 Non-U.S. 12.3 9.9 9.7 Current tax expense 54.4 56.8 59.0 Deferred tax expense (benefit): U.S. Federal (3.0 ) (10.9 ) 5.1 State (1.7 ) (1.9 ) 0.4 Non-U.S. (1.9 ) (1.1 ) (0.8 ) Deferred tax expense, net (6.6 ) (13.9 ) 4.7 Income tax expense $ 47.8 $ 42.9 $ 63.7 The following table provides our income before income taxes and equity in net income (loss) of unconsolidated entities, generated by our U.S. and non-U.S. operations: Year ended December 31 (in millions) 2018 2017 2016 U.S. $ 188.2 $ 143.5 $ 186.5 Non-U.S. 44.7 37.6 38.4 Income before income taxes and equity in net loss of unconsolidated entities $ 232.9 $ 181.1 $ 224.9 Deferred Tax Assets and Liabilities We recognize deferred income taxes for the temporary differences between the carrying amount of assets and liabilities for financial statement purposes and their tax basis. The tax effects of the temporary differences that give rise to the deferred income tax assets and liabilities are as follows: As of December 31 (in millions) 2018 2017 Deferred tax assets: Stock-based compensation expense $ 4.7 $ 3.7 Accrued liabilities 17.0 14.2 Deferred revenue 3.7 3.5 Net operating loss carryforwards - U.S. federal and state 0.2 1.9 Net operating loss carryforwards - Non-U.S. 2.4 3.1 Credits and incentive carryforwards — 0.3 Deferred royalty revenue 0.3 0.2 Allowance for doubtful accounts 1.4 1.1 Deferred rent 7.4 6.2 Unrealized exchange losses, net 0.2 — Other 0.6 0.3 Total deferred tax assets 37.9 34.5 Deferred tax liabilities: Acquired intangible assets (16.5 ) (18.6 ) Property, equipment, and capitalized software (26.7 ) (24.6 ) Unrealized exchange gains, net — (0.6 ) Prepaid expenses (7.1 ) (3.9 ) Investments in unconsolidated entities (4.8 ) (5.4 ) Withholding tax - foreign dividends (3.0 ) (3.0 ) Total deferred tax liabilities (58.1 ) (56.1 ) Net deferred tax liability before valuation allowance (20.2 ) (21.6 ) Valuation allowance (2.0 ) (2.0 ) Deferred tax liability, net $ (22.2 ) $ (23.6 ) The deferred tax assets and liabilities are presented in our Consolidated Balance Sheets as follows: As of December 31 (in millions) 2018 2017 Deferred tax liability, net $ (22.2 ) $ (23.6 ) The following table summarizes our U.S. net operating loss (NOL) carryforwards: As of December 31 (in millions) 2018 2017 Expiration Dates Expiration Dates U.S. federal NOLs subject to expiration dates $ 1.0 2023 $ 9.1 2023-2036 The net decrease in the U.S. federal NOL carryforwards as of December 31, 2018 compared with 2017 primarily reflects the utilization of U.S. federal NOLs. We have not recorded a valuation allowance against the U.S. federal NOLs of $1.0 million because we expect the benefit of the U.S. federal NOLs to be fully utilized before expiration. The following table summarizes our NOL carryforwards for our non-U.S. operations: As of December 31 (in millions) 2018 2017 Non-U.S. NOLs subject to expiration dates from 2019 through 2038 $ 5.5 $ 5.7 Non-U.S. NOLs with no expiration date 5.1 9.1 Total $ 10.6 $ 14.8 Non-U.S. NOLs not subject to valuation allowances $ 2.0 $ 5.4 The change in non-U.S. NOL carryforwards as of December 31, 2018 compared with 2017 primarily reflects the use of NOL carryforwards offset by NOLs generated. In assessing the realizability of our deferred tax assets, we consider whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. We have recorded a valuation allowance against all but approximately $2.0 million of the non-U.S. NOLs, reflecting the likelihood that the benefit of these NOLs will not be realized. Unrecognized Tax Benefits We conduct business globally and as a result, we file income tax returns in U.S. federal, state, local, and foreign jurisdictions. In the normal course of business, we are subject to examination by tax authorities throughout the world. The open tax years for our U.S. Federal tax returns and most state tax returns include the years 2015 to the present. We are currently under audit by state and local tax authorities in the U.S. as well as tax authorities in certain non-U.S. jurisdictions. It is likely that the examination phase of some of these state, local, and non-U.S. audits will conclude in 2019 . It is not possible to estimate the effect of current audits on previously recorded unrecognized tax benefits. As of December 31, 2018 , our Consolidated Balance Sheet included a current liability of $6.6 million and a non-current liability of $7.1 million for unrecognized tax benefits. As of December 31, 2017 , our Consolidated Balance Sheet included a current liability of $8.7 million and a noncurrent liability of $7.0 million for unrecognized tax benefits. These amounts include interest and penalties, less any associated tax benefits. The table below reconciles the beginning and ending amount of the gross unrecognized tax benefits as follows: (in millions) 2018 2017 Gross unrecognized tax benefits - beginning of the year $ 18.7 $ 18.4 Increases as a result of tax positions taken during a prior-year period 0.8 1.4 Decreases as a result of tax positions taken during a prior-year period (0.3 ) (0.4 ) Increases as a result of tax positions taken during the current period 1.6 1.9 Decreases relating to settlements with tax authorities (2.5 ) — Reductions as a result of lapse of the applicable statute of limitations (5.2 ) (2.6 ) Gross unrecognized tax benefits - end of the year $ 13.1 $ 18.7 In 2018 , we recorded a net increase of $2.1 million of gross unrecognized tax benefits before settlements and lapses of statutes of limitations, of which $2.1 million increased our income tax expense by $2.1 million . In addition, we reduced our unrecognized tax benefits by $7.7 million for settlements and lapses of statutes of limitations, of which $1.5 million decreased our income tax expense by $1.4 million . The reduction in our unrecognized tax benefits and the decrease to our tax expense for settlements and lapses of statutes of limitation were attributable to the following: • In the first quarter of 2018, we settled certain of our U.S. federal and state tax audits including our federal audit for the tax periods covering 2008 to 2012. The impact of the audit settlements decreased our gross unrecognized tax benefits by $2.4 million but the impact on our tax expense was nominal because the liabilities that we reserved for these audits were approximate to the final settlement amounts. • In second and third quarters of 2018, there were lapses of statutes of limitation for unsuccessful state refund claims which decreased our gross unrecognized tax benefits by $3.4 million . We did not previously record a financial statement benefit for the state refund claims, and, therefore, this decrease had no impact on our income tax expense. • In the third and fourth quarters of 2018, there were other lapses of statutes of limitation, which decreased our gross unrecognized tax benefits by $1.9 million and our income tax expense by $1.4 million . As of December 31, 2018 , we had $13.1 million of gross unrecognized tax benefits, of which $13.1 million , if recognized, would reduce our effective income tax rate and decrease our income tax expense by $12.6 million . We record interest and penalties related to uncertain tax positions as part of our income tax expense. The following table summarizes our gross liability for interest and penalties: As of December 31 (in millions) 2018 2017 Liabilities for interest and penalties $ 1.3 $ 1.7 We recorded the decrease in the liabilities for penalties and interest, net of any tax benefits, to income tax expense in our Consolidated Statement of Income in 2018 .

Contingencies

Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Michael D. Green In August 2017, Michael D. Green, individually and purportedly on behalf of all others similarly situated, filed a complaint in the U.S. District Court for the Northern District of Illinois. The complaint named as defendants Morningstar, Inc., Prudential Investment Management Services LLC, and Prudential Retirement Insurance and Annuity Co., and contained one count alleging violation of the Racketeer Influenced and Corrupt Organizations Act (RICO). Plaintiff, a participant in a pension plan, alleged that the defendants engaged in concerted racketeering actions to steer plan participants into high-cost investments that pay unwarranted fees to the defendants. The complaint sought unspecified compensatory damages for plaintiff and the members of the putative class, treble damages, injunctive relief, costs, and attorneys’ fees. We filed a motion to dismiss the complaint for failure to state a claim, which the court granted without prejudice on March 16, 2018. On April 13, 2018, plaintiff filed an amended complaint, substituting Morningstar Investment Management LLC for Morningstar, Inc. as a defendant, and which again contained one count alleging violation of RICO and sought unspecified compensatory damages for plaintiff and the members of the putative class, treble damages, injunctive relief, costs, and attorneys' fees. We moved to dismiss the amended complaint on May 11, 2018, which the court granted with prejudice on January 16, 2019. No appeal was taken by the deadline for doing so. Data Audits and Reviews In our global data business, we include in our products or directly redistribute to our customers data and information licensed from third-party vendors. Our compliance with the terms of these licenses is subject to audit by the third-party vendors, and we also regularly review our compliance with the terms of the licenses. We are undergoing several such third-party vendor audits and internal reviews, and the results and findings may indicate that we may be required to make a payment for prior data usage. Due to lack of available information and data, as well as potential variations of the audit or internal review findings, we are not able to reasonably estimate a possible loss, or range of losses for some matters. While we cannot predict the outcomes, we do not believe the results of any audits will have a material adverse effect on our business, operating results, or financial position. We record accrued liabilities for litigation, regulatory, and other business matters when those matters represent loss contingencies that are both probable and estimable. In these cases, there may be an exposure to loss in excess of any amounts accrued. When a loss contingency is not both probable and estimable, we do not establish an accrued liability. As a litigation, regulatory, or other business matter develops, we evaluate on an ongoing basis whether such matter presents a loss contingency that is probable and estimable. Other Matters We are involved from time to time in legal proceedings and litigation that arise in the normal course of our business. While it is difficult to predict the outcome of any particular proceeding, we do not believe the result of any of these matters will have a material adverse effect on our business, operating results, or financial position.

Share Repurchase Program

Share Repurchase Program	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Share Repurchase Program	Share Repurchase Program In December 2017, the board of directors approved a new share repurchase program that authorizes the company to repurchase up to $500.0 million in shares of the company's outstanding common stock effective January 1, 2018. The authorization expires on December 31, 2020 . We may repurchase shares from time to time at prevailing market prices on the open market or in private transactions in amounts that we deem appropriate. As of December 31, 2018 , we had repurchased a total of 202,245 shares for $20.9 million under this authorization, leaving $479.1 million available for future repurchases.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Recently Issued Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted accounting pronouncements Revenue Recognition: On May 28, 2014, the FASB issued ASU No. 2014-09 (Topic 606), Revenue from Contracts with Customers , which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The original effective date for ASU 2014-09 would have required us to adopt it beginning on January 1, 2017. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers — Deferral of the Effective Date , which deferred the effective date of ASU 2014-09 for one year and permitted early adoption as early as the original effective date. We elected the deferral, and the new standard was effective for us on January 1, 2018. We also adopted ASU No. 2016-08, ASU No. 2016-10, ASU No. 2016-11, ASU No. 2016-12, and ASU No. 2016-20 on January 1, 2018. We adopted Topic 606 using the modified retrospective transition method applied to those contracts which were not completed as of January 1, 2018. Upon adoption, we recognized the cumulative effect of adopting this guidance as an adjustment to our opening balance of retained earnings. Prior periods were not retrospectively adjusted. The impact to revenue as a result of applying Topic 606 was an increase of $6.7 million for the year ended December 31, 2018 and relates to a change in presentation of revenue and costs associated with third-party content and data. Such revenue and costs were presented on a net basis prior to the adoption of Topic 606 and are now presented on a gross basis. We also changed our accounting for expenses related to our sales commission plans as a result of adopting Topic 606. Due to our method of adoption, we recorded a deferred commission asset, and related deferred tax liability, as of January 1, 2018 for sales commissions that were expensed in prior periods. This change resulted in an opening net adjustment to retained earnings of $17.0 million , with an offsetting increase to our deferred commissions and deferred income tax liabilities relating to prior periods. The following table summarizes the cumulative effect of the changes to our unaudited condensed consolidated balance sheet as of January 1, 2018 from the adoption of Topic 606: (in millions) Balance at December 31, 2017 Adjustments due to Topic 606 Balance at January 1, 2018 Assets: Deferred commissions, current and non-current $ — $ 22.7 $ 22.7 Liabilities: Deferred income tax liability $ — $ 5.7 $ 5.7 Equity: Retained earnings $ — $ 17.0 $ 17.0 The following table illustrates the impact that adopting Topic 606 has had on our reported results in the audited consolidated balance sheet as of December 31, 2018 and the audited consolidated statements of income for the year ended December 31, 2018: As of December 31, 2018 (in millions) As Reported Impact of adopting Topic 606 Balances without adoption of Topic 606 Balance Sheet: Accounts receivable, less allowance $ 172.2 $ — $ 172.2 Deferred commissions, current and non-current 25.1 25.1 — Deferred revenue, current and non-current 210.0 — 210.0 2018 (in millions) As Reported Impact of adopting Topic 606 Balances without adoption of Topic 606 Income Statement: Revenue $ 1,019.9 $ 6.7 $ 1,013.2 Cost of revenue 411.1 6.7 404.4 Sales and marketing 148.5 2.9 151.4 Operating income 215.8 (2.9 ) 212.9 Intangibles — Goodwill and Other: On January 26, 2017, the FASB issued ASU No. 2017-04, Intangibles — Goodwill and Other , which simplifies the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. 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. All other goodwill impairment guidance will remain largely unchanged. Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The same one-step impairment test will be applied to goodwill at all reporting units, even those with zero or negative carrying amounts. Entities will be required to disclose the amount of goodwill at reporting units with zero or negative carrying amounts. The new standard is effective for us on January 1, 2020. The new standard is required to be applied prospectively. Early adoption is permitted for any impairment tests performed after January 1, 2017. We elected to early adopt the new standard on October 1, 2018 as we perform our annual impairment review in the fourth quarter. The adoption did not have an impact on our consolidated financial statements and related disclosures. Recently Issued Accounting Pronouncements Not Yet Adopted Leases: On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , which will require lessees to recognize almost all leases on their balance sheet as a right-of-use asset and a lease liability. The new standard became effective for us on January 1, 2019. The new standard originally required the use of a modified retrospective approach upon adoption. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842) - Targeted Improvements , which allows an additional transition method to adopt the new lease standard at the adoption date instead of the beginning of the earliest period presented, and recognize a cumulative-effect adjustment to the beginning balance of retained earnings in the period of adoption. We elected this transition method at the adoption date of January 1, 2019. We continue to evaluate the effect that the new standard will have on our consolidated financial statements and related disclosures. We are making meaningful progress on our implementation plan and are achieving project milestones, including a comprehensive review of our lease portfolio to identify all leases where the company is either a lessor or lessee. In addition, we implemented lease accounting software in early 2019 to assist in our ongoing lease data collection, tracking and analysis, and are updating our lease processes and related internal controls to reflect changes required to ensure readiness for adoption. We are updating our accounting policies and plan to make an accounting policy election to keep leases with an initial term of 12 months or less off of the balance sheet. We also plan to recognize those lease payments in the Consolidated Statements of Income on a straight-line basis over the lease term. We do not believe the new standard will have a material impact on our liquidity. The adoption of the new lease standard will have no impact on our debt-covenant compliance under our current agreements. Income Statement-Reporting Comprehensive Income: On February 14, 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , to address a specific consequence of the Tax Reform Act by allowing a reclassification from accumulated other comprehensive income (loss) to retained earnings for stranded tax effects resulting from the Tax Reform Act’s reduction of the U.S. federal corporate income tax rate. The new standard became effective for us on January 1, 2019 and is to be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Reform Act is recognized. We are evaluating the effect that the new standard will have on our consolidated financial statements and related disclosures. Compensation—Stock Compensation: On June 20, 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718) - Improvements to Nonemployee Share-Based Payment Accounting, which aligns the accounting for share-based payment awards issued to employees and nonemployees. Under the new standard, the existing employee guidance will apply to nonemployee share-based transactions (as long as the transaction is not effectively a form of financing), with the exception of specific guidance related to the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. In addition, the contractual term can be used in lieu of an expected term in the option-pricing model for nonemployee awards. The new standard became effective for us on January 1, 2019 and should be applied to all new awards granted after the date of adoption. We are evaluating the effect that the new standard will have on our consolidated financial statements and related disclosures. Cloud Computing : On August 29, 2018, the FASB issued ASU No. 2018-15, Customer's Accounting for Fees Paid in a Cloud Computing Arrangement , which helps entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement (CCA) by providing guidance for determining when an arrangement includes a software license and when an arrangement is solely a hosted CCA service. Under the new standard, customers will apply the same criteria for capitalizing implementation costs as they would for an arrangement that has a software license. The new guidance also prescribes the balance sheet, income statement, and cash flow classification of the capitalized implementation costs and related amortization expense, and requires additional quantitative and qualitative disclosures. The new standard is effective for us on January 1, 2020. Early adoption is permitted, including adoption in any interim period for which financial statements have not been issued. Entities can choose to adopt the new guidance prospectively to eligible costs incurred on or after the date this guidance is first applied or retrospectively. We are evaluating the effect that the new standard will have on our consolidated financial statements and related disclosures.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data	Selected Quarterly Financial Data (unaudited) 2017 2018 (in millions except per share amounts) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Revenue $209.5 $229.2 $ 229.9 $ 243.1 $ 243.5 $ 252.4 $ 261.3 (1) $ 262.7 Total operating expense 181.1 183.2 177.1 200.5 196.0 198.8 195.9 213.4 Operating income 28.4 46.0 52.8 42.6 47.5 53.6 65.4 49.3 Non-operating income (expense), net (1.3) 15.3 (2) (2.0 ) (0.7 ) 9.3 (2) 1.4 7.3 (0.9 ) Income before income taxes and equity in net income (loss) of unconsolidated entities 27.1 61.3 50.8 41.9 56.8 55.0 72.7 48.4 Equity in net income (loss) of unconsolidated entities (0.8) (0.2) — (0.3 ) (1.5 ) (0.4 ) 0.3 (0.5 ) Income tax expense 8.3 15.0 16.9 2.7 (3) 13.4 12.8 16.1 5.5 Consolidated net income $18.0 $46.1 $ 33.9 $ 38.9 $ 41.9 $ 41.8 $ 56.9 $ 42.4 Net income per share: Basic $0.42 $1.07 $ 0.80 $ 0.91 $ 0.99 $ 0.98 $ 1.33 $ 0.99 Diluted $0.42 $1.07 $ 0.79 $ 0.91 $ 0.98 $ 0.97 $ 1.32 $ 0.99 Dividends per common share: Dividends declared per common share $0.23 $0.23 $ — $ 0.48 $ 0.25 $ 0.25 $ — $ 0.53 Dividends paid per common share $0.23 $0.23 $ 0.23 $ 0.23 $ 0.25 $ 0.25 $ 0.25 $ 0.25 Weighted average shares outstanding: Basic 42.9 42.9 42.5 42.5 42.5 42.6 42.6 42.7 Diluted 43.2 43.1 42.8 42.9 42.9 43.0 43.1 43.1 (1) Revenue in the third quarter of 2018 includes a $10.5 million revenue benefit related to an amended license agreement. (2) Non-operating income in the second quarter of 2017 included a $17.5 million gain on the sale of HelloWallet. We recorded an immaterial adjustment to this gain in the fourth quarter of 2017. Non-operating income in first quarter of 2018 includes a $10.5 million gain related to the sale of our 15(c) board consulting services product line. (3) Tax expense in the fourth quarter of 2017 includes a net benefit of $10.6 million related to the impact of the Tax Reform Act.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation. We conduct our business operations through wholly owned or majority-owned operating subsidiaries. The accompanying consolidated financial statements include the accounts of Morningstar, Inc. and our subsidiaries. We consolidate assets, liabilities, and results of operations of subsidiaries in which we have a controlling interest and eliminate all significant intercompany accounts and transactions. We account for investments in entities in which we exercise significant influence, but do not control, using the equity method. As part of our investment management operations, we manage certain funds outside of the U.S. that are considered variable interest entities. For the majority of these variable interest entities, we do not have a variable interest. In cases where we do have a variable interest, we are not the primary beneficiary. Accordingly, we do not consolidate any of these variable interest entities.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses during the reporting period. Actual results may differ from these estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents. Cash and cash equivalents consist of cash and investments with original maturities of three months or less. We state them at cost, which approximates fair value. We state the portion of our cash equivalents that are invested in money market funds at fair value, as these funds are actively traded and have quoted market prices.
Investments	Investments. We account for our investments in accordance with FASB ASC 320, Investments—Debt and Equity Securities. We classify our investments into three categories: held-to-maturity, trading, and available-for-sale. • Held-to-maturity: We classify certain investments, primarily certificates of deposit, as held-to-maturity securities, based on our intent and ability to hold these securities to maturity. We record held-to-maturity investments at amortized cost in our Consolidated Balance Sheets. • Trading: We classify certain other investments, primarily equity securities, as trading securities as these relate mainly to investments tracking the strategies of our newsletter portfolios. We include realized and unrealized gains and losses associated with these investments as a component of our operating income in our Consolidated Statements of Income. We record these securities at their fair value in our Consolidated Balance Sheets. • Available-for-sale: Investments not considered held-to-maturity or trading securities are classified as available-for-sale securities. Available-for-sale securities primarily consist of equity securities, exchange-traded funds, and mutual funds. We report unrealized gains and losses for available-for-sale securities as other comprehensive income (loss), net of related income taxes. We record these securities at their fair value in our Consolidated Balance Sheets.
Fair Value Measurements	Fair Value Measurements. FASB ASC 820, Fair Value Measurements (FASB ASC 820) defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. Under FASB ASC 820, 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 as of the measurement date. The standard applies whenever other standards require (or permit) assets or liabilities to be measured at fair value. FASB ASC 820 uses a fair value hierarchy based on three broad levels of valuation inputs: • Level 1: Valuations based on quoted prices in active markets for identical assets or liabilities that the company has the ability to access. • Level 2: Valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. • Level 3: Valuations based on inputs that are unobservable and significant to the overall fair value measurement. We provide additional information about our cash equivalents and investments that are subject to valuation under FASB ASC 820 in Note 7 . We classify our investments into three categories: available-for-sale, held-to-maturity, and trading. Our investment portfolio consists of stocks, bonds, options, mutual funds, money market funds, or exchange-traded products that replicate the model portfolios and strategies created by Morningstar. These investment accounts may also include exchange-traded products where Morningstar is an index provider.
Concentration of Credit Risk	Concentration of Credit Risk. No single customer is large enough to pose a significant credit risk to our operations or financial condition. For the years ended December 31, 2018 , 2017 , and 2016 , no single customer represented 5% or more of our consolidated revenue. If receivables from our customers become delinquent, we begin a collections process. We maintain an allowance for doubtful accounts based on our estimate of the probable losses of accounts receivable.
Property, Equipment, and Depreciation	Property, Equipment, and Depreciation. We state property and equipment at historical cost, net of accumulated depreciation. We depreciate property and equipment primarily using the straight-line method based on the useful life of the asset, which generally is three years. We amortize leasehold improvements over the lease term or their useful lives, whichever is shorter.
Computer Software and Internal Product Development Costs	Computer Software and Internal Product Development Costs. We capitalize certain costs in accordance with FASB ASC 350-40, Internal-Use Software , FASB ASC 350-50, Website Development Costs, and FASB ASC 985, Software . Internal product development costs mainly consist of employee costs for developing new web-based products and certain major enhancements of existing products. We amortize these costs on a straight-line basis over the estimated economic life, which is generally three years. We include capitalized software development costs related to projects that have not been placed into service in our construction in progress balance.
Business Combinations	Business Combinations . When we make acquisitions, we allocate the purchase price to the assets acquired, liabilities assumed, and goodwill. We follow FASB ASC 805, Business Combinations . We recognize and measure the fair value of the acquired operation as a whole, as well as the assets acquired and liabilities assumed, at their full fair values as of the date we obtain control, regardless of the percentage ownership in the acquired operation or how the acquisition was achieved. We expense direct costs related to the business combination, such as advisory, accounting, legal, valuation, and other professional fees, as incurred. We recognize restructuring costs, including severance and relocation for employees of the acquired entity, as post-combination expenses unless the target entity meets the criteria of FASB ASC 420, Exit or Disposal Cost Obligations , on the acquisition date. As part of the purchase price allocation, we follow the requirements of FASB ASC 740, Income Taxes. This includes establishing deferred tax assets or liabilities reflecting the difference between the values assigned for financial statement purposes and income tax purposes. In certain acquisitions, the goodwill resulting from the purchase price allocation may not be deductible for income tax purposes. FASB ASC 740 prohibits recognition of a deferred tax asset or liability for temporary differences in goodwill if goodwill is not amortizable and deductible for tax purposes.
Goodwill	Goodwill . Changes in the carrying amount of our recorded goodwill are mainly the result of business acquisitions, divestitures, and the effect of foreign currency translations. In accordance with FASB ASC 350, Intangibles—Goodwill and Other , we do not amortize goodwill; instead, goodwill is subject to an impairment test annually, or whenever indicators of impairment exist. An impairment would occur if the carrying amount of a reporting unit exceeded the fair value of that reporting unit. We performed annual impairment reviews in the fourth quarter of 2018 and 2017 . We did not record any impairment losses in 2018 , 2017 , and 2016.
Intangible Assets	Intangible Assets. We amortize intangible assets using the straight-line method over their estimated useful lives, which range from one to 20 years. We have no intangible assets with indefinite useful lives. In accordance with FASB ASC 360-10-35, Subsequent Measurement—Impairment or Disposal of Long-Lived Assets , we review intangible assets for impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. If the value of future undiscounted cash flows is less than the carrying amount of an asset group, we record an impairment loss based on the excess of the carrying amount over the fair value of the asset group. We did not record any impairment losses in 2018 , 2017 , and 2016.
Revenue Recognition	Revenue Recognition. On January 1, 2018, we began recognizing revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers . The Company has retained much of the same accounting treatment used to recognize revenue under ASC Topic 606 as under accounting standards in effect in prior periods (see Note 18 for additional information). Under ASC Topic 606, we recognize revenue by applying the following five-step model to each of our customer arrangements: 1. Identify the customer contract; 2. Identify the performance obligations in the contract; 3. Determine the transaction price; 4. Allocate the transaction price to the performance obligations; and 5. Recognize revenue when (or as) performance obligations are satisfied. Revenues are recognized when (or as) performance obligations are satisfied by transferring a promised product or service to the customer. Products or services are transferred when (or as) the customer obtains control of the product or service. The transaction price for a customer arrangement is the amount we expect to be entitled to in exchange for transferring the promised product or service. The transaction price may include fixed amounts, variable amounts, or both. Amounts invoiced in excess of the revenue recognized for the services transferred during the period will result in an increase to deferred revenue. The timing of cash payments is typically thirty to sixty days after the performance obligation has been satisfied and these payments reduce our outstanding accounts receivable. Revenue from contracts with customers is derived from license-based arrangements, asset-based arrangements, and transaction-based arrangements. License-based revenue is generated through subscription contracts with our customers of Morningstar Data, Morningstar Direct, Morningstar Advisor Workstation, Morningstar Enterprise Components, PitchBook Data, and other similar products. Our performance obligations under these contracts are typically satisfied over time, as the customer has access to the product or service during the term of the subscription license and the level of service is consistent during the contract period. Therefore, we recognize revenue for these performance obligations on a straight-line basis, typically over terms of 12 to 36 months . Asset-based revenue is generated through consulting service contracts with our customers of Morningstar Investment Management, Workplace Solutions, and Morningstar Indexes. Our performance obligations under these contracts are satisfied over time as the customer receives continuous access to a service for the contract term. We recognize revenue over the contract term based on the value of assets under management and a tiered fee agreed to with the customer (typically in a range of 30 - 55 basis points of the customer’s average daily portfolio balance). Asset-based arrangements typically have a term of 12 to 36 months . The fees from such arrangements represent variable consideration, and the customer does not make separate purchasing decisions that result in additional performance obligations. Significant changes in the underlying fund assets, or significant disruptions in the market, are evaluated to determine if revisions on estimates of earned asset-based fees for the current quarter are needed. An estimate of variable consideration is included in the initial transaction price only to the extent it is probable that a significant reversal in the amount of revenue recognized will not occur. Estimates of asset-based fees are based on the most recently reported quarter, and, as a result, it is unlikely a significant reversal of revenue would occur. Transaction-based revenue is generated through contracts with our customers for Internet advertising, Morningstar Conferences, and Morningstar Credit Ratings. Our performance obligations for Internet advertising and Morningstar Conferences are satisfied as the service is delivered, and therefore we recognize revenue when the performance obligation is satisfied (as the customer’s advertisements are displayed and at the completion of the Morningstar Conference). Our performance obligations for Morningstar Credit Ratings include the issuance of the rating and may include surveillance services for a period of time as agreed with the customer. We allocate the transaction price to the deliverables based on their relative selling price, which is generally based on the price we charge when the same deliverable is sold separately. Our performance obligation for the issuance of the rating is satisfied when the rating is issued, which is when we recognize the related revenue. Our performance obligations for surveillance services is satisfied over time, as the customer has access to the service during the surveillance period and the level of service is consistent during the contract period. Therefore, we recognize revenue for this performance obligation on a straight-line basis. Our contracts with customers may include multiple performance obligations. For most of these arrangements, we generally allocate revenue to each performance obligation based on its estimated standalone selling price. We generally determine standalone selling prices based on prices charged to customers when the same performance obligation is sold separately. Our contracts with customers may include third-party involvement in providing goods or services to the customer. The inclusion of third-party content does not result in separate performance obligations because is it not delivered separately from the other license obligations. In these arrangements, the customer has contracted to receive a single, bundled solution with third-party and Morningstar content delivered via Morningstar’s subscription services. Revenue and related costs of revenue from third-party content is presented on a gross basis within the condensed consolidated financial statements. We record taxes imposed on revenue-producing transactions (such as sales, use, value-added, and some excise taxes) on a net basis; therefore, we exclude such taxes from revenue in our Consolidated Statements of Income. Deferred revenue represents the portion of licenses or subscriptions billed or collected in advance of the service being provided which we expect to recognize as revenue in future periods. Certain arrangements may have cancellation or refund provisions. If we make a refund, it typically reflects the amount collected from a customer for which we have not yet provided services. The refund therefore results in a reduction of deferred revenue.
Sales Commissions	Sales Commissions. Under prior accounting standards, the Company expensed sales incentive compensation costs, (sales commissions) as incurred. However, upon adopting ASC Topic 606 and ASC 340-40, Other Assets and Deferred Costs - Contracts with Customers , on January 1, 2018 (see Note 18 for additional information), we began capitalizing sales commissions, which are considered directly attributable to obtaining a customer contract. Such costs are capitalized using a portfolio approach that aggregates these costs by legal entity within their geographical regions. Capitalized sales commissions are amortized using the straight-line method over a period that is consistent with the transfer of the products or services to the customer to which the sales commission relates. The period of transfer for each portfolio is the shorter of the weighted-average customer life, or the economic life of the underlying technology that delivers the products or services. As of December 31, 2018, the period of transfer was determined to be two to three years. Discretionary amounts which are added to sales commission payments are expensed as incurred, as they are not considered to be directly attributable to obtaining a customer contract.
Advertising Costs	Advertising Costs. Advertising costs include expenses incurred for various print and Internet ads, search engine fees, and direct mail campaigns. We expense advertising costs as incurred.
Stock-Based Compensation Expense	Stock-Based Compensation Expense. We account for our stock-based compensation expense in accordance with FASB ASC 718, Compensation—Stock Compensation . Our stock-based compensation expense reflects grants of restricted stock units, restricted stock, performance share awards, market stock units, and stock options. We measure the fair value of our restricted stock units, restricted stock, and performance share awards on the date of grant based on the closing market price of Morningstar's common stock on the day prior to grant. For market stock units, we estimate the fair value of the awards using a Monte Carlo valuation model. For stock options, we estimate the fair value of our stock options on the date of grant using a Black-Scholes option-pricing model. We amortize the fair values to stock-based compensation expense, net of estimated forfeitures, ratably over the vesting period. We estimate expected forfeitures of all employee stock-based awards and recognize compensation cost only for those awards expected to vest. We determine forfeiture rates based on historical experience and adjust the estimated forfeitures to actual forfeiture experience as needed.
Liability for Sabbatical Leave	Liability for Sabbatical Leave. In some of our locations, we offer employees a sabbatical leave. Although the sabbatical policy varies by region, Morningstar's full-time employees are generally eligible for six weeks of paid time off after four years of continuous service. We account for our sabbatical liability in accordance with FASB ASC 710-10-25 , Compensated Absences . We record a liability for employees' sabbatical benefits over the period employees earn the right for sabbatical leave and include this liability in Accrued Compensation in our Consolidated Balance Sheet.
Income Taxes	Income Taxes. We record deferred income taxes for the temporary differences between the carrying amount of assets and liabilities for financial statement purposes and tax purposes in accordance with FASB ASC 740, Income Taxes (FASB ASC 740). FASB ASC 740 prescribes the minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. It also provides guidance on derecognition, measurement, classification, interest and penalties, accounting in interim periods, and disclosure for uncertain tax positions. We recognize interest and penalties related to unrecognized tax benefits as part of income tax expense in our Consolidated Statements of Income. We classify liabilities related to unrecognized tax benefits as either current or long-term liabilities in our Consolidated Balance Sheet, depending on when we expect to make payment.
Segment Information	Segment Information We report our results in a single reportable segment, which reflects how our chief operating decision maker allocates resources and evaluates our financial results. Because we have a single reportable segment, all required financial segment information can be found directly in the Consolidated Financial Statements. The accounting policies for our reportable segment are the same as those described in Note 2 . We evaluate the performance of our reporting segment based on revenue and operating income.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Acronyms Used	The acronyms that appear in these Notes to our Consolidated Financial Statements refer to the following: ASC Accounting Standards Codification ASU Accounting Standards Update EITF Emerging Issues Task Force FASB Financial Accounting Standards Board SEC Securities and Exchange Commission
Summary of Depreciation for Internally Developed Software	The table below summarizes our depreciation expense related to internally developed software for the past three years: (in millions) 2018 2017 2016 Internally developed software depreciation expense $ 42.8 $ 30.6 $ 20.0
Summary of Capitalized Software Development Costs	The table below summarizes our capitalized software development costs for the past three years: (in millions) 2018 2017 2016 Capitalized software development costs $ 53.5 $ 46.3 $ 28.2
Summary of Advertising Expense	The table below summarizes our advertising expense for the past three years: (in millions) 2018 2017 2016 Advertising expense $ 6.4 $ 7.0 $ 7.6

Income Per Share (Tables)

Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table shows how we reconcile our net income and the number of shares used in computing basic and diluted income per share: (in millions, except per share amounts) 2018 2017 2016 Basic net income per share attributable to Morningstar, Inc.: Net income attributable to Morningstar, Inc. $ 183.0 $ 136.9 $ 161.0 Weighted average common shares outstanding 42.6 42.7 43.0 Basic net income per share attributable to Morningstar, Inc. $ 4.30 $ 3.21 $ 3.74 Diluted net income per share attributable to Morningstar, Inc.: Net income attributable to Morningstar, Inc. $ 183.0 $ 136.9 $ 161.0 Weighted average common shares outstanding 42.6 42.7 43.0 Net effect of dilutive stock options and restricted stock units 0.4 0.3 0.3 Weighted average common shares outstanding for computing diluted income per share 43.0 43.0 43.3 Diluted net income per share attributable to Morningstar, Inc. $ 4.25 $ 3.18 $ 3.72

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents our revenue disaggregated by revenue type. Sales and usage-based taxes are excluded from revenue. Year ended December 31 (in millions) 2018 2017 2016 License-based $ 751.6 $ 667.7 $ 579.4 Asset-based 200.4 182.2 163.6 Transaction-based 67.9 61.8 55.6 Consolidated revenue $ 1,019.9 $ 911.7 $ 798.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction	We expect to recognize revenue related to our contract liabilities for 2019 and subsequent years as follows: (in millions) As of December 31, 2018 2019 $ 388.9 2020 93.7 2021 28.0 2022 11.0 2023 5.4 Thereafter 43.6 $ 570.6
Summary of Contract Assets and Change in Deferred Commissions	The following table summarizes our contract assets balance: (in millions) As of December 31, 2018 As of December 31, 2017 Accounts receivable, less allowance for doubtful accounts $ 172.2 $ 148.2 Deferred commissions 14.8 — Deferred commissions, non-current 10.3 — Total contract assets $ 197.3 $ 148.2 The following table shows the change in our deferred commissions balance from January 1, 2018 to December 31, 2018 : (in millions) Balance as of January 1, 2018 $ 22.7 Commissions earned and capitalized 19.4 Amortization of capitalized amounts (17.0 ) Balance as of December 31, 2018 $ 25.1

Segment and Geographical Area_2

Segment and Geographical Area Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	The tables below summarize our revenue and long-lived assets by geographical area: External revenue by geographical area Year ended December 31 (in millions) 2018 2017 2016 United States $ 764.2 $ 687.0 $ 590.5 United Kingdom 72.4 64.7 61.1 Continental Europe 81.2 69.9 62.6 Australia 40.9 34.6 32.2 Canada 30.7 29.4 28.2 Asia 24.5 21.2 20.0 Other 6.0 4.9 4.0 Total International 255.7 224.7 208.1 Consolidated revenue $ 1,019.9 $ 911.7 $ 798.6 Long-lived assets by geographical area As of December 31 (in millions) 2018 2017 United States $ 126.4 $ 131.9 United Kingdom 3.8 6.0 Continental Europe 1.3 1.7 Australia 5.0 2.3 Canada 0.3 0.2 Asia 6.5 5.2 Other 0.2 0.1 Total International 17.1 15.5 Consolidated property, equipment, and capitalized software, net $ 143.5 $ 147.4 The long-lived asset by geographical area does not include deferred commissions, non-current as the balance is not significant.

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Investments	We classify our investment portfolio as shown below: As of December 31 (in millions) 2018 2017 Available-for-sale $ 20.1 $ 21.5 Held-to-maturity 2.5 21.9 Trading securities 4.0 1.7 Total $ 26.6 $ 45.1
Unrealized Gain (Loss) on Investments	The following table shows the cost, unrealized gains (losses), and fair values related to investments classified as available-for-sale and held-to-maturity: As of December 31, 2018 As of December 31, 2017 (in millions) Cost Unrealized Gain Unrealized Loss Fair Value Cost Unrealized Gain Unrealized Loss Fair Value Available-for-sale: Equity securities and exchange-traded funds $ 17.9 $ 1.2 $ (1.8 ) $ 17.3 $ 17.1 $ 2.4 $ (0.6 ) $ 18.9 Mutual funds 3.0 — (0.2 ) 2.8 2.4 0.2 — 2.6 Total $ 20.9 $ 1.2 $ (2.0 ) $ 20.1 $ 19.5 $ 2.6 $ (0.6 ) $ 21.5 Held-to-maturity: Certificates of deposit $ 2.5 $ — $ — $ 2.5 $ 19.9 $ — $ — $ 19.9 Convertible note — — — — 2.0 — — 2.0 Total $ 2.5 $ — $ — $ 2.5 $ 21.9 $ — $ — $ 21.9
Investments Classified by Contractual Maturity Date	The table below shows the cost and fair value of investments classified as available-for-sale and held-to-maturity based on their contractual maturities as of December 31, 2018 and December 31, 2017 . As of December 31, 2018 As of December 31, 2017 (in millions) Cost Fair Value Cost Fair Value Available-for-sale: Equity securities, exchange-traded funds, and mutual funds $ 20.9 $ 20.1 $ 19.5 $ 21.5 Total $ 20.9 $ 20.1 $ 19.5 $ 21.5 Held-to-maturity: Due in one year or less $ 2.3 $ 2.3 $ 19.7 $ 19.7 Due in one to three years 0.2 0.2 2.2 2.2 Total $ 2.5 $ 2.5 $ 21.9 $ 21.9
Schedule of Realized Gain (Loss)	The following table shows the realized gains and losses arising from sales of our investments classified as available-for-sale recorded in our Consolidated Statements of Income: (in millions) 2018 2017 2016 Realized gains $ 1.8 $ 3.4 $ 1.6 Realized losses (0.8 ) (0.2 ) (1.0 ) Realized gains, net $ 1.0 $ 3.2 $ 0.6
Unrealized Gain Loss On Trading Securities	The following table shows the net unrealized gains (losses) on trading securities as recorded in our Consolidated Statements of Income: (in millions) 2018 2017 2016 Unrealized gains (losses), net $ (0.2 ) $ 0.1 $ —
Fair Value, Assets Measured on Recurring Basis	The table below shows the fair value of our assets subject to fair value measurements that are measured at fair value on a recurring basis using a fair value hierarchy: Level 1: Valuations based on quoted prices in active markets for identical assets or liabilities that we have the ability to access. Level 2: Valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3: Valuations based on inputs that are unobservable and significant to the overall fair value measurement. Fair Value Fair Value Measurements as of December 31, 2018 as of Using Fair Value Hierarchy (in millions) December 31, 2018 Level 1 Level 2 Level 3 Available-for-sale investments Equity securities and exchange-traded funds $ 17.3 $ 17.3 $ — $ — Mutual funds 2.8 2.8 — — Trading securities 4.0 4.0 — — Cash equivalents 0.1 0.1 — — Total $ 24.2 $ 24.2 $ — $ — Fair Value Fair Value Measurements as of December 31, 2017 as of Using Fair Value Hierarchy (in millions) December 31, 2017 Level 1 Level 2 Level 3 Available-for-sale investments Equity securities and exchange-traded funds $ 18.9 $ 18.9 $ — $ — Mutual funds 2.6 2.6 — — Trading securities 1.7 1.7 — — Cash equivalents 0.5 0.5 — — Total $ 23.7 $ 23.7 $ — $ —

Acquisitions, Goodwill, and O_2

Acquisitions, Goodwill, and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Acquisitions, Goodwill, and Other Intangible Assets [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes our allocation of the estimated fair values of the assets acquired and liabilities assumed at the date of acquisition: (in millions) Cash and cash equivalents $ 12.4 Accounts receivable 10.8 Other current and non-current assets 3.2 Intangible assets 60.7 Goodwill 192.0 Deferred revenue (22.0 ) Deferred tax liability, net (12.3 ) Other current and non-current liabilities (9.7 ) Total fair value of PitchBook $ 235.1
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The allocation includes $60.7 million of acquired intangible assets, as follows: (in millions) Weighted Average Useful Life (years) Customer-related assets $ 17.1 10 Technology-based assets 40.8 5 Intellectual property (trademarks and trade names) 2.8 4 Total intangible assets $ 60.7 6
Pro Forma Information	Unaudited Pro Forma Financial Information (in millions) 2016 2015 Revenue $ 834.1 $ 813.3 Operating income 157.7 170.0 Net income 105.5 117.1 Basic net income per share attributable to Morningstar, Inc. $ 2.45 $ 2.65 Diluted net income per share attributable to Morningstar, Inc. $ 2.44 $ 2.65
Schedule of Goodwill	The following table shows the changes in our goodwill balances from January 1, 2017 to December 31, 2018 : (in millions) Balance as of January 1, 2017 $ 556.8 Divestiture of HelloWallet (See Note 9) (2.4 ) Foreign currency translation and adjustments to purchase price allocation 10.5 Balance as of December 31, 2017 $ 564.9 Other, primarily foreign currency translation (8.2 ) Balance as of December 31, 2018 $ 556.7
Schedule of Intangible Assets	The following table summarizes our intangible assets: As of December 31, 2018 As of December 31, 2017 (in millions) Gross Accumulated Amortization Net Weighted Average Useful Life (years) Gross Accumulated Amortization Net Weighted Average Useful Life (years) Intellectual property $ 30.8 $ (29.2 ) $ 1.6 9 $ 31.5 $ (28.9 ) $ 2.6 9 Customer-related assets 153.0 (111.7 ) 41.3 12 156.6 (108.1 ) 48.5 12 Supplier relationships 0.2 (0.1 ) 0.1 20 0.2 (0.1 ) 0.1 20 Technology-based assets 126.9 (96.3 ) 30.6 7 127.9 (84.2 ) 43.7 7 Non-competition agreements 2.4 (2.1 ) 0.3 5 2.5 (2.0 ) 0.5 5 Total intangible assets $ 313.3 $ (239.4 ) $ 73.9 10 $ 318.7 $ (223.3 ) $ 95.4 10
Schedule of Intangible Asset, Amortization Expense	The following table summarizes our amortization expense related to intangible assets: (in millions) 2018 2017 2016 Amortization expense $ 20.7 $ 23.6 $ 19.4
Schedule of Expected Amortization Expense	Based on acquisitions and divestitures completed through December 31, 2018 , we expect intangible amortization expense for 2019 and subsequent years to be as follows: (in millions) 2019 $ 19.2 2020 16.2 2021 12.9 2022 5.0 2023 5.0 Thereafter 15.6

Divestitures (Tables)

Divestitures (Tables)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations	The following table summarizes the amounts included in the gain on sale of business for the year ended December 31, 2017: Year ended December 31 (in millions) 2017 Proceeds received $ 23.7 Intangibles and internally developed software (4.5 ) Goodwill (2.4 ) Other assets and liabilities (0.1 ) Total gain on sale of business $ 16.7

Investments in Unconsolidated_2

Investments in Unconsolidated Entities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments in Unconsolidated Entities [Abstract]
Schedule of Equity Method And Cost Method Investments	Our investments in unconsolidated entities consist primarily of the following: As of December 31 (in millions) 2018 2017 Investment in MJKK $ 23.9 $ 26.4 Investment in Sustainalytics 25.7 20.7 Other-equity method investments 10.3 12.6 Investments accounted for using the cost method 3.2 2.3 Total investments in unconsolidated entities $ 63.1 $ 62.0
Schedule of Equity Method Investments	The following table summarizes our ownership percentage in MJKK and the market value of this investment based on MJKK’s publicly quoted share price: As of December 31 2018 2017 Morningstar’s approximate ownership of MJKK 30 % 34 % Approximate market value of Morningstar’s ownership in MJKK: Japanese yen (¥ in millions) ¥ 7,525.4 ¥ 10,649.6 Equivalent U.S. dollars ($ in millions) $ 68.4 $ 94.6

Property, Equipment, and Capi_2

Property, Equipment, and Capitalized Software (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property, Equipment, and Capitalized Software by Major Category	The following table shows our property, equipment, and capitalized software summarized by major category: As of December 31 (in millions) 2018 2017 Capitalized software $ 294.8 $ 239.2 Capitalized equipment 83.5 81.6 Furniture and fixtures 29.6 27.6 Leasehold improvements 77.3 72.5 Telephone equipment 2.1 2.3 Construction in progress 7.9 8.9 Property, equipment, and capitalized software, at cost 495.2 432.1 Less accumulated depreciation (351.7 ) (284.7 ) Property, equipment, and capitalized software, net $ 143.5 $ 147.4
Summary of Depreciation Expense	The following table summarizes our depreciation expense: (in millions) 2018 2017 2016 Depreciation expense $ 76.0 $ 67.6 $ 51.3

Operating Leases Operating Leas

Operating Leases Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Leases, Operating [Abstract]
Schedule of Minimum Future Rental Commitments	The following table shows our minimum future rental commitments due in each of the next five years and thereafter for all non-cancelable operating leases, consisting primarily of commitments for office space: Minimum Future Rental Commitments (in millions) 2019 $ 34.4 2020 36.0 2021 32.2 2022 20.8 2023 15.1 Thereafter 47.7 Total $ 186.2
Schedule of Rent Expense	The following table summarizes our rent expense, including taxes, insurance, and related operating costs: (in millions) 2018 2017 2016 Rent expense $ 32.5 $ 30.3 $ 26.3
Schedule of Deferred Rent	Deferred rent includes build-out and rent abatement allowances received, which are amortized over the remaining portion of the original term of the lease as a reduction in office lease expense. We include deferred rent, as appropriate, in “Accounts payable and accrued liabilities” and “Deferred rent, noncurrent” on our Consolidated Balance Sheets. As of December 31 (in millions) 2018 2017 Deferred rent $ 28.6 $ 31.2

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Shares Available for Future Grants	The following table summarizes the number of shares available for future grants under our 2011 Plan: As of December 31 (in millions) 2018 Shares available for future grants 3.1
Schedule of Stock-Based Compensation Expense	The following table summarizes our stock-based compensation expense and the related income tax benefit we recorded in the past three years: Year ended December 31 (in millions) 2018 2017 2016 Restricted stock units $ 19.8 $ 16.5 $ 14.6 Performance share awards 10.2 7.1 (0.1 ) Market stock units 1.7 0.5 — Total stock-based compensation expense $ 31.7 $ 24.1 $ 14.5 Income tax benefit related to the stock-based compensation expense $ 7.0 $ 7.8 $ 4.3
Allocation of Stock-based Compensation Expense	The following table summarizes the stock-based compensation expense included in each of our operating expense categories for the past three years: Year ended December 31 (in millions) 2018 2017 2016 Cost of revenue $ 11.7 $ 9.6 $ 7.5 Sales and marketing 3.5 3.0 1.9 General and administrative 16.5 11.5 5.1 Total stock-based compensation expense $ 31.7 $ 24.1 $ 14.5
Schedule of Uncategorized Stock-Based Compensation Expense	The following table summarizes the amount of unrecognized stock-based compensation expense as of December 31, 2018 and the expected number of months over which the expense will be recognized: Unrecognized stock-based compensation expense (in millions) Weighted average expected amortization period (months) Restricted stock units $ 36.9 33 Market stock units 5.2 28 Total unrecognized stock-based compensation expense $ 42.1 32
Schedule of Restricted Stock Units Award Activity	The following table summarizes restricted stock unit activity during the past three years: Restricted Stock Units (RSUs) Unvested Vested but Deferred Total Weighted Average Grant Date Value per RSU RSUs Outstanding - December 31, 2015 572,526 14,924 587,450 $ 72.14 Granted 241,609 — 241,609 77.82 Dividend equivalents 370 136 506 56.52 Vested (225,590 ) — (225,590 ) 69.39 Issued — (5,312 ) (5,312 ) 44.47 Forfeited (47,670 ) — (47,670 ) 74.45 RSUs Outstanding - December 31, 2016 541,245 9,748 550,993 $ 75.77 Granted 331,470 — 331,470 78.33 Dividend equivalents — 78 78 60.99 Vested (212,005 ) — (212,005 ) 75.38 Issued — (6,547 ) (6,547 ) 49.40 Forfeited (55,831 ) — (55,831 ) 76.49 RSUs Outstanding - December 31, 2017 604,879 3,279 608,158 $ 77.52 Granted 243,614 — 243,614 108.60 Dividend equivalents — 16 16 73.28 Vested (279,774 ) — (279,774 ) 80.68 Issued — (3,295 ) (3,295 ) 73.28 Forfeited (41,254 ) — (41,254 ) 86.47 RSUs Outstanding - December 31, 2018 527,465 — 527,465 $ 89.53
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Performance-Based Units, Vested and Expected to Vest [Table Text Block]	The table below shows target performance share awards granted and shares that would be issued at current performance levels for performance share awards granted as of December 31, 2018 : As of December 31, 2018 Target performance share awards granted 41,439 Weighted average fair value per award $ 81.71 Number of shares that would be issued based on current performance levels — Unamortized expense, based on current performance levels (in millions) $ — The table below shows target performance share awards granted and shares that will be issued based on final performance levels for performance share awards granted as of December 31, 2018 : As of December 31, 2018 Target performance share awards granted 77,716 Weighted average fair value per award $ 95.53 Number of shares that will be issued based on final 2018 performance levels 106,854 Unamortized expense, based on current performance levels (in millions) $ —
Market Units, Valuation Assumptions	We used the following assumptions to estimate the fair value of our market stock units during 2017 and 2018 : Assumptions for Monte Carlo Valuation Model Grant Date Expected volatility Dividend yield Risk-free interest rate May 15, 2017 17.4 % 1.20 % 1.49 % November 15, 2017 17.7 % 1.04 % 1.79 % May 15, 2018 17.4 % 0.89 % 2.70 % November 15, 2018 19.6 % 0.83 % 2.92 %
Schedule of Market Stocks Units	The table below shows market stock units granted and target market stock units outstanding as of December 31, 2018 : As of December 31, 2018 Market stock units granted 84,153 Weighted average fair value per award $ 89.58 Number of target market stock units outstanding 81,274 Unamortized expense, based on current performance levels (in millions) $ 5.2
Schedule of Stock Options, Valuation Assumptions	The weighted average fair value of options granted during 2011 was $23.81 per share, based on the following assumptions: Assumptions for Black-Scholes Option Pricing Model Expected life (years) 7.4 Volatility factor 35.1 % Dividend yield 0.35 % Interest rate 2.87 %
Schedule of All Other Option Granted	The following table summarizes stock option activity in the past three years for our various stock option grants: 2018 2017 2016 Option Grants Underlying Shares Weighted Average Exercise Price Underlying Shares Weighted Average Exercise Price Underlying Shares Weighted Average Exercise Price Options outstanding—beginning of year 41,685 $ 57.28 46,001 $ 57.28 52,096 $ 57.52 Granted — — — — — — Canceled — — — — — — Exercised (1,000 ) 57.28 (4,316 ) 57.28 (6,095 ) 59.35 Options outstanding—end of year 40,685 $ 57.28 41,685 $ 57.28 46,001 $ 57.28 Options exercisable—end of year 40,685 $ 57.28 41,685 $ 57.28 46,001 $ 57.28
Schedule of Intrinsic Value of Stock Options Exercised During Period	The following table summarizes the total intrinsic value (difference between the market value of our stock on the date of exercise and the exercise price of the option) of options exercised: (in millions) 2018 2017 2016 Intrinsic value of options exercised $ 0.1 $ 0.1 $ 0.1
Schedule of Options, Vested and Expected to Vest, Outstanding and Exercisable	The table below shows additional information for options outstanding and exercisable as of December 31, 2018 : Options Outstanding Options Exercisable Range of Exercise Prices Number of Options Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Aggregate Intrinsic Value (in millions) Exercisable Shares Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Aggregate Intrinsic Value (in millions) $57.28 40,685 2.37 $ 57.28 $ 2.1 40,685 2.37 $ 57.28 $ 2.1 Vested or Expected to Vest $57.28 40,685 2.37 $ 57.28 $ 2.1

Defined Contribution Plan (Tabl

Defined Contribution Plan (Tables)	12 Months Ended
	Dec. 31, 2018
Defined Contribution Plan [Abstract]
Schedule of Defined Contribution Plan, Employer Matching Contributions	The following table summarizes our matching contributions: (in millions) 2018 2017 2016 401(k) matching contributions $ 11.0 $ 10.4 $ 9.0

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Schedule of Income Tax Expense and Effective Tax Rate	The following table shows our income tax expense and our effective tax rate for the years ended December 31, 2018 , 2017 , and 2016 : (in millions) 2018 2017 2016 Income before income taxes and equity in net loss of unconsolidated entities $ 232.9 $ 181.1 $ 224.9 Equity in net loss of unconsolidated entities (2.1 ) (1.3 ) (0.2 ) Total $ 230.8 $ 179.8 $ 224.7 Income tax expense $ 47.8 $ 42.9 $ 63.7 Effective tax rate 20.7 % 23.9 % 28.3 %
Schedule of Effective Income Tax Rate Reconciliation	The following table reconciles our income tax expense at the U.S. federal income tax rate to income tax expense as recorded: 2018 2017 2016 (in millions, except percentages) Amount % Amount % Amount % Income tax expense at U.S. federal rate $ 48.5 21.0 % $ 63.0 35.0 % $ 78.6 35.0 % State income taxes, net of federal income tax benefit 7.4 3.2 3.0 1.7 4.5 2.0 Change in U.S. tax rate (0.6 ) (0.3 ) (14.7 ) (8.2 ) — — Deemed mandatory repatriation (1.2 ) (0.5 ) 7.5 4.2 — — Reduction of deferred tax liabilities for foreign equity method investments (0.5 ) (0.2 ) (6.4 ) (3.6 ) — — Withholding tax - repatriation — — 3.0 1.7 — — Stock-based compensation activity (2.6 ) (1.1 ) 0.3 0.2 (0.6 ) (0.3 ) Equity in net income of unconsolidated subsidiaries (including holding gains upon acquisition) 1.0 0.4 1.2 0.7 (12.1 ) (5.4 ) Book gain over tax gain on sale of HelloWallet — — (6.8 ) (3.8 ) — — Net change in valuation allowance related to non-U.S. deferred tax assets, primarily net operating losses (0.2 ) (0.1 ) 0.1 0.1 (0.1 ) — Difference between U.S. federal statutory and foreign tax rates 0.2 0.1 (5.2 ) (2.9 ) (5.3 ) (2.4 ) Change in unrecognized tax benefits 1.0 0.4 1.2 0.7 2.6 1.2 Credits and incentives (3.6 ) (1.6 ) (3.7 ) (2.1 ) (3.7 ) (1.6 ) GILTI tax 1.4 0.6 — — — — FDII deduction (5.1 ) (2.2 ) — — — — Other - net 2.1 0.9 0.4 0.2 (0.2 ) (0.1 ) Total income tax expense $ 47.8 20.7 % $ 42.9 23.9 % $ 63.7 28.3 %
Schedule of Components of Income Tax Expense	Income tax expense consists of the following: Year ended December 31 (in millions) 2018 2017 2016 Current tax expense: U.S. Federal $ 31.0 $ 40.3 $ 42.8 State 11.1 6.6 6.5 Non-U.S. 12.3 9.9 9.7 Current tax expense 54.4 56.8 59.0 Deferred tax expense (benefit): U.S. Federal (3.0 ) (10.9 ) 5.1 State (1.7 ) (1.9 ) 0.4 Non-U.S. (1.9 ) (1.1 ) (0.8 ) Deferred tax expense, net (6.6 ) (13.9 ) 4.7 Income tax expense $ 47.8 $ 42.9 $ 63.7
Schedule of Income before Income Tax	The following table provides our income before income taxes and equity in net income (loss) of unconsolidated entities, generated by our U.S. and non-U.S. operations: Year ended December 31 (in millions) 2018 2017 2016 U.S. $ 188.2 $ 143.5 $ 186.5 Non-U.S. 44.7 37.6 38.4 Income before income taxes and equity in net loss of unconsolidated entities $ 232.9 $ 181.1 $ 224.9
Schedule of Deferred Tax Assets and Liabilities	The tax effects of the temporary differences that give rise to the deferred income tax assets and liabilities are as follows: As of December 31 (in millions) 2018 2017 Deferred tax assets: Stock-based compensation expense $ 4.7 $ 3.7 Accrued liabilities 17.0 14.2 Deferred revenue 3.7 3.5 Net operating loss carryforwards - U.S. federal and state 0.2 1.9 Net operating loss carryforwards - Non-U.S. 2.4 3.1 Credits and incentive carryforwards — 0.3 Deferred royalty revenue 0.3 0.2 Allowance for doubtful accounts 1.4 1.1 Deferred rent 7.4 6.2 Unrealized exchange losses, net 0.2 — Other 0.6 0.3 Total deferred tax assets 37.9 34.5 Deferred tax liabilities: Acquired intangible assets (16.5 ) (18.6 ) Property, equipment, and capitalized software (26.7 ) (24.6 ) Unrealized exchange gains, net — (0.6 ) Prepaid expenses (7.1 ) (3.9 ) Investments in unconsolidated entities (4.8 ) (5.4 ) Withholding tax - foreign dividends (3.0 ) (3.0 ) Total deferred tax liabilities (58.1 ) (56.1 ) Net deferred tax liability before valuation allowance (20.2 ) (21.6 ) Valuation allowance (2.0 ) (2.0 ) Deferred tax liability, net $ (22.2 ) $ (23.6 )
Schedule of Deferred Tax Assets and Liabilities Included in Consolidated Balance Sheets	The deferred tax assets and liabilities are presented in our Consolidated Balance Sheets as follows: As of December 31 (in millions) 2018 2017 Deferred tax liability, net $ (22.2 ) $ (23.6 )
Schedule of Gross Unrecognized Tax Benefits	The table below reconciles the beginning and ending amount of the gross unrecognized tax benefits as follows: (in millions) 2018 2017 Gross unrecognized tax benefits - beginning of the year $ 18.7 $ 18.4 Increases as a result of tax positions taken during a prior-year period 0.8 1.4 Decreases as a result of tax positions taken during a prior-year period (0.3 ) (0.4 ) Increases as a result of tax positions taken during the current period 1.6 1.9 Decreases relating to settlements with tax authorities (2.5 ) — Reductions as a result of lapse of the applicable statute of limitations (5.2 ) (2.6 ) Gross unrecognized tax benefits - end of the year $ 13.1 $ 18.7
Summary of Income Tax Examinations	The following table summarizes our gross liability for interest and penalties: As of December 31 (in millions) 2018 2017 Liabilities for interest and penalties $ 1.3 $ 1.7
U.S [Member]
Operating Loss Carryforwards [Line Items]
Summary of Operating Loss Carryforwards	The following table summarizes our U.S. net operating loss (NOL) carryforwards: As of December 31 (in millions) 2018 2017 Expiration Dates Expiration Dates U.S. federal NOLs subject to expiration dates $ 1.0 2023 $ 9.1 2023-2036
Non-U.S. [Member]
Operating Loss Carryforwards [Line Items]
Summary of Operating Loss Carryforwards	The following table summarizes our NOL carryforwards for our non-U.S. operations: As of December 31 (in millions) 2018 2017 Non-U.S. NOLs subject to expiration dates from 2019 through 2038 $ 5.5 $ 5.7 Non-U.S. NOLs with no expiration date 5.1 9.1 Total $ 10.6 $ 14.8 Non-U.S. NOLs not subject to valuation allowances $ 2.0 $ 5.4

Recently Issued Accounting Pr_2

Recently Issued Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Impact of Adoption of Topic 606	The following table summarizes the cumulative effect of the changes to our unaudited condensed consolidated balance sheet as of January 1, 2018 from the adoption of Topic 606: (in millions) Balance at December 31, 2017 Adjustments due to Topic 606 Balance at January 1, 2018 Assets: Deferred commissions, current and non-current $ — $ 22.7 $ 22.7 Liabilities: Deferred income tax liability $ — $ 5.7 $ 5.7 Equity: Retained earnings $ — $ 17.0 $ 17.0 The following table illustrates the impact that adopting Topic 606 has had on our reported results in the audited consolidated balance sheet as of December 31, 2018 and the audited consolidated statements of income for the year ended December 31, 2018: As of December 31, 2018 (in millions) As Reported Impact of adopting Topic 606 Balances without adoption of Topic 606 Balance Sheet: Accounts receivable, less allowance $ 172.2 $ — $ 172.2 Deferred commissions, current and non-current 25.1 25.1 — Deferred revenue, current and non-current 210.0 — 210.0 2018 (in millions) As Reported Impact of adopting Topic 606 Balances without adoption of Topic 606 Income Statement: Revenue $ 1,019.9 $ 6.7 $ 1,013.2 Cost of revenue 411.1 6.7 404.4 Sales and marketing 148.5 2.9 151.4 Operating income 215.8 (2.9 ) 212.9

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	2017 2018 (in millions except per share amounts) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Revenue $209.5 $229.2 $ 229.9 $ 243.1 $ 243.5 $ 252.4 $ 261.3 (1) $ 262.7 Total operating expense 181.1 183.2 177.1 200.5 196.0 198.8 195.9 213.4 Operating income 28.4 46.0 52.8 42.6 47.5 53.6 65.4 49.3 Non-operating income (expense), net (1.3) 15.3 (2) (2.0 ) (0.7 ) 9.3 (2) 1.4 7.3 (0.9 ) Income before income taxes and equity in net income (loss) of unconsolidated entities 27.1 61.3 50.8 41.9 56.8 55.0 72.7 48.4 Equity in net income (loss) of unconsolidated entities (0.8) (0.2) — (0.3 ) (1.5 ) (0.4 ) 0.3 (0.5 ) Income tax expense 8.3 15.0 16.9 2.7 (3) 13.4 12.8 16.1 5.5 Consolidated net income $18.0 $46.1 $ 33.9 $ 38.9 $ 41.9 $ 41.8 $ 56.9 $ 42.4 Net income per share: Basic $0.42 $1.07 $ 0.80 $ 0.91 $ 0.99 $ 0.98 $ 1.33 $ 0.99 Diluted $0.42 $1.07 $ 0.79 $ 0.91 $ 0.98 $ 0.97 $ 1.32 $ 0.99 Dividends per common share: Dividends declared per common share $0.23 $0.23 $ — $ 0.48 $ 0.25 $ 0.25 $ — $ 0.53 Dividends paid per common share $0.23 $0.23 $ 0.23 $ 0.23 $ 0.25 $ 0.25 $ 0.25 $ 0.25 Weighted average shares outstanding: Basic 42.9 42.9 42.5 42.5 42.5 42.6 42.6 42.7 Diluted 43.2 43.1 42.8 42.9 42.9 43.0 43.1 43.1 (1) Revenue in the third quarter of 2018 includes a $10.5 million revenue benefit related to an amended license agreement. (2) Non-operating income in the second quarter of 2017 included a $17.5 million gain on the sale of HelloWallet. We recorded an immaterial adjustment to this gain in the fourth quarter of 2017. Non-operating income in first quarter of 2018 includes a $10.5 million gain related to the sale of our 15(c) board consulting services product line. (3) Tax expense in the fourth quarter of 2017 includes a net benefit of $10.6 million related to the impact of the Tax Reform Act.

Description of Business (Detail

Description of Business (Details)	Dec. 31, 2017Countries
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of countries in which entity operates	27

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)Yearsweek	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Depreciation expense	$ 76	$ 67.6	$ 51.3
Capitalized software development costs	$ 53.5	$ 46.3	28.2
Intangible assets useful life	10 years	10 years
Advertising expense	$ 6.4	$ 7	7.6
Number of paid time off weeks that full-time employees are eligible to take for sabbatical leave | week	6
Number of years of continuous service required for full-time employees to take sabbatical leave | Years	4
Minimum [Member]
Business Acquisition [Line Items]
Intangible assets useful life	1 year
Revenue timing of cash payments	30 days
Revenue performance period	12 months
Revenue, basis over customer's average daily portfolio balance	0.30
Sales commissions, period of transfer	2 years
Maximum [Member]
Business Acquisition [Line Items]
Intangible assets useful life	20 years
Revenue timing of cash payments	60 days
Revenue performance period	36 months
Revenue, basis over customer's average daily portfolio balance	0.55
Sales commissions, period of transfer	3 years
Internally developed software expense [Member]
Business Acquisition [Line Items]
Depreciation expense	$ 42.8	$ 30.6	$ 20
Property and equipment [Member]
Business Acquisition [Line Items]
Asset useful life	3 years
Capitalized software [Member]
Business Acquisition [Line Items]
Asset useful life	3 years

Credit Arrangements (Details)

Credit Arrangements (Details)	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Line of Credit Facility [Line Items]
Long-term debt	$ 70,000,000	$ 70,000,000	$ 180,000,000
Credit agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	300,000,000	300,000,000
Long-term debt	70,000,000	70,000,000
Remaining borrowing capacity	230,000,000	230,000,000
Letters of credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 25,000,000	$ 25,000,000
London Interbank Offered Rate (LIBOR) [Member] | Credit agreement [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate debt	1.00%
Maximum [Member]
Line of Credit Facility [Line Items]
Debt covenant, consolidated leverage ratio		3
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate debt		1.75%
Maximum [Member] | Lender's base rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate debt		2.75%
Minimum [Member]
Line of Credit Facility [Line Items]
Debt covenant, consolidated interest coverage ratio		3
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate debt		1.00%
Minimum [Member] | Lender's base rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate debt		2.00%

Income Per Share (Details)

Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic net income per share attributable to Morningstar, Inc.:
Net income attributable to Morningstar, Inc.									$ 183	$ 136.9	$ 161
Weighted average common shares outstanding (in shares)	42.7	42.6	42.6	42.5	42.5	42.5	42.9	42.9	42.6	42.7	43
Basic net income per share attributable to Morningstar, Inc. (in dollars per share)									$ 4.30	$ 3.21	$ 3.74
Diluted net income per share attributable to Morningstar, Inc.:
Net income attributable to Morningstar, Inc.									$ 183	$ 136.9	$ 161
Weighted average common shares outstanding (in shares)	42.7	42.6	42.6	42.5	42.5	42.5	42.9	42.9	42.6	42.7	43
Net effect of dilutive stock options and restricted stock units (in shares)									0.4	0.3	0.3
Weighted average common shares outstanding for computing diluted income per share (in shares)	43.1	43.1	43	42.9	42.9	42.8	43.1	43.2	43	43	43.3
Diluted net income per share attributable to Morningstar, Inc. (in dollars per share)									$ 4.25	$ 3.18	$ 3.72

Revenue (Disaggregation of Reve

Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Consolidated revenue	$ 1,019.9	$ 911.7	$ 798.6
License-based
Disaggregation of Revenue [Line Items]
Consolidated revenue	751.6	667.7	579.4
Asset-based
Disaggregation of Revenue [Line Items]
Consolidated revenue	200.4	182.2	163.6
Transaction-based
Disaggregation of Revenue [Line Items]
Consolidated revenue	$ 67.9	$ 61.8	$ 55.6

Revenue (Disaggregation of Re_2

Revenue (Disaggregation of Revenue, Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	$ 1,019.9	$ 911.7	$ 798.6
Minimum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue performance period	12 months
Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue performance period	36 months
Licensed-based Revenue
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	$ 751.6	667.7	579.4
Licensed-based Revenue | Minimum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue performance period	12 months			12 months
Licensed-based Revenue | Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue performance period	36 months			36 months
Asset-based Revenue
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues	$ 200.4	$ 182.2	$ 163.6
Asset-based Revenue | Minimum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue performance period	12 months			12 months
Asset-based Revenue | Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue performance period	36 months			36 months

Revenue (Contract Liabilities,

Revenue (Contract Liabilities, Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Increase in contract liabilities from cash payments received	$ 24.5
Revenues recognized	163
Contract liability	$ 210
Minimum [Member]
Disaggregation of Revenue [Line Items]
Revenue performance period	12 months
Maximum [Member]
Disaggregation of Revenue [Line Items]
Revenue performance period	36 months

Revenue (Contract Liabilities_2

Revenue (Contract Liabilities, Expected Recognition) (Details) $ in Millions	Dec. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 388.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	93.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	28
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	11
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	5.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	43.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 570.6

Revenue (Summary of Contract As

Revenue (Summary of Contract Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Accounts receivable, less allowance for doubtful accounts	$ 172.2	$ 148.2
Deferred commissions	14.8	0
Deferred commissions, non-current	10.3	0
Total contract assets	$ 197.3	$ 148.2

Revenue (Change in Deferred Com

Revenue (Change in Deferred Commissions) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Balance as of January 1, 2018	$ 22.7
Commissions earned and capitalized	19.4
Amortization of capitalized amounts	(17)
Balance as of December 31, 2018	$ 25.1

Segment and Geographical Area_3

Segment and Geographical Area Information (Operating Segments) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information, Operating Income (Loss) [Abstract]
External revenue	$ 262.7	$ 261.3	$ 252.4	$ 243.5	$ 243.1	$ 229.9	$ 229.2	$ 209.5	$ 1,019.9	$ 911.7	$ 798.6
Stock-based compensation expense									31.7	24.1	14.5
Depreciation and amortization									96.7	91.2	70.7
Operating income	49.3	$ 65.4	$ 53.6	$ 47.5	42.6	$ 52.8	$ 46	$ 28.4	215.8	169.8	180.8
Segment Reporting Information, Additional Information [Abstract]
Goodwill	$ 556.7				$ 564.9				556.7	564.9	556.8
United States [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
External revenue									$ 764.2	$ 687	$ 590.5

Segment and Geographical Area_4

Segment and Geographical Area Information (External Revenue and Long-Lived Assets) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 262.7	$ 261.3	$ 252.4	$ 243.5	$ 243.1	$ 229.9	$ 229.2	$ 209.5	$ 1,019.9	$ 911.7	$ 798.6
Long-lived assets	143.5				147.4				143.5	147.4
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									764.2	687	590.5
Long-lived assets	126.4				131.9				126.4	131.9
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									72.4	64.7	61.1
Long-lived assets	3.8				6				3.8	6
Europe excluding the United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									81.2	69.9	62.6
Long-lived assets	1.3				1.7				1.3	1.7
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									40.9	34.6	32.2
Long-lived assets	5				2.3				5	2.3
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									30.7	29.4	28.2
Long-lived assets	0.3				0.2				0.3	0.2
Asia, Excluding Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									24.5	21.2	20
Long-lived assets	6.5				5.2				6.5	5.2
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									6	4.9	4
Long-lived assets	0.2				0.1				0.2	0.1
Non United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									255.7	224.7	$ 208.1
Long-lived assets	$ 17.1				$ 15.5				$ 17.1	$ 15.5

Investments and Fair Value Me_3

Investments and Fair Value Measurements (Classification of Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Available-for-sale	$ 20.1	$ 21.5
Held-to-maturity	2.5	21.9
Trading securities, fair value disclosure	4	1.7
Total	$ 26.6	$ 45.1

Investments and Fair Value Me_4

Investments and Fair Value Measurements (Gains (Losses) on Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale:
Available-for-sale securities, amortized cost basis	$ 20,900	$ 19,500
Available-for-sale securities, unrealized gain	1,200	2,600
Available-for-sale securities, unrealized loss	(2,000)	(600)
Available-for-sale securities, current	20,100	21,500
Held-to-maturity:
Held-to-maturity securities, total amortized cost	2,500	21,900
Held-to-maturity securities, unrealized gain	0	0
Held-to-maturity securities, unrealized loss	0	0
Held-to-maturity securities, current	2,500	21,900
Debt Securities, Available-for-sale, Realized Gain (Loss) [Abstract]
Available-for-sale securities, realized gains	1,800	3,400	$ 1,600
Available-for-sale securities, realized losses	(800)	(200)	(1,000)
Available-for-sale securities, realized gains, net	1,000	3,200	$ 600
Equity securities and exchange-traded funds
Available-for-sale:
Available-for-sale securities, amortized cost basis	17,900	17,100
Available-for-sale securities, unrealized gain	1,200	2,400
Available-for-sale securities, unrealized loss	(1,800)	(600)
Available-for-sale securities, fair value disclosure	17,300	18,900
Mutual funds
Available-for-sale:
Available-for-sale securities, amortized cost basis	3,000	2,400
Available-for-sale securities, unrealized gain	0	200
Available-for-sale securities, unrealized loss	(200)	0
Available-for-sale securities, fair value disclosure	2,800	2,600
Convertible note
Held-to-maturity:
Held-to-maturity securities, total amortized cost		2,000
Held-to-maturity securities, unrealized gain		0
Held-to-maturity securities, unrealized loss		0
Held-to-maturity securities, current		2,000
Certificates of deposit [Member]
Held-to-maturity:
Held-to-maturity securities, total amortized cost	2,500	19,900
Held-to-maturity securities, unrealized gain	0	0
Held-to-maturity securities, unrealized loss	0	0
Held-to-maturity securities, current	2,500	$ 19,900
Convertible note
Held-to-maturity:
Held-to-maturity securities, total amortized cost	0
Held-to-maturity securities, unrealized gain	0
Held-to-maturity securities, unrealized loss	0
Held-to-maturity securities, current	$ 0

Investments and Fair Value Me_5

Investments and Fair Value Measurements (Cost and Fair Value of Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale securities, equity securities and mutual funds, amortized cost basis	$ 20.9	$ 19.5
Available-for-sale securities, equity securities and mutual funds, fair value	20.1	21.5
Available-for-sale securities, amortized cost basis	20.9	19.5
Available-for-sale securities, current	20.1	21.5
Debt Securities, Held-to-maturity, Maturity [Abstract]
Held-to-maturity securities, due within one year, net carrying amount	2.3	19.7
Held-to-maturity securities, due within one year, fair value	2.3	19.7
Held-to-maturity securities, due within one year, carrying amount	0.2	2.2
Held-to-maturity securities, due within one year, fair value	0.2	2.2
Held-to-maturity securities, total amortized cost	2.5	21.9
Held-to-maturity securities, current	$ 2.5	$ 21.9

Investments and Fair Value Me_6

Investments and Fair Value Measurements (Unrealized Gains on Trading Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Unrealized gains (losses), net	$ (0.2)	$ 0.1	$ 0

Investments and Fair Value Me_7

Investments and Fair Value Measurements (Fair Value of Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value disclosure	$ 4	$ 1.7
Equity securities and exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	17.3	18.9
Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	2.8	2.6
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value disclosure	4	1.7
Cash equivalents, fair value disclosure	0.1	0.5
Investments, fair value disclosure	24.2	23.7
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity securities and exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	17.3	18.9
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	2.8	2.6
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value disclosure	0	0
Cash equivalents, fair value disclosure	0	0
Investments, fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity securities and exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value disclosure	0	0
Cash equivalents, fair value disclosure	0	0
Investments, fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity securities and exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities, fair value disclosure	4	1.7
Cash equivalents, fair value disclosure	0.1	0.5
Investments, fair value disclosure	24.2	23.7
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities and exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	17.3	18.9
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	$ 2.8	$ 2.6

Acquisitions, Goodwill, and O_3

Acquisitions, Goodwill, and Other Intangible Assets (Narrative) (Details) - USD ($)	Dec. 01, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2016
Business Acquisition [Line Items]
Holding gain upon acquisition of additional ownership of equity-method investments			$ 17,500,000	$ 0	$ 0	$ 37,100,000
Impairment of intangible assets				0	0	0
Goodwill		$ 556,800,000	$ 564,900,000	556,700,000	564,900,000	556,800,000
Goodwill impairment loss				$ 0	$ 0	$ 0
PitchBook [Member]
Business Acquisition [Line Items]
Percentage of voting interests acquired	78.20%
Percentage of voting interest after subsequent acquisition (percent)	100.00%
Percentage of voting interest before subsequent acquisition (percent)							22.00%
Pro Forma, revenue, actual		4,100,000
Pro Forma, income (expense), actual		$ 7,500,000
Acquisition estimated fair value	$ 235,100,000
Cash paid to acquire the entity	188,200,000
Equity method investments, fair value	46,900,000
Book value prior to business acquisition							$ 9,800,000
Holding gain upon acquisition of additional ownership of equity-method investments	37,100,000
Intangible assets	60,700,000
Deferred tax liability	(12,300,000)
Goodwill	$ 192,000,000

Acquisitions, Goodwill, and O_4

Acquisitions, Goodwill, and Other Intangible Assets (Purchase Price Allocation) (Details) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 01, 2016
Business Acquisition, Purchase Price Allocation [Abstract]
Goodwill	$ 556.7	$ 564.9	$ 556.8
PitchBook [Member]
Business Acquisition, Purchase Price Allocation [Abstract]
Cash and cash equivalents				$ 12.4
Accounts receivable and other current assets				10.8
Other non-current assets				3.2
Intangible assets				60.7
Goodwill				192
Deferred revenue				(22)
Deferred tax liability				(12.3)
Other current and non-current liabilities				(9.7)
Acquisition estimated fair value				$ 235.1

Acquisitions, Goodwill, and O_5

Acquisitions, Goodwill, and Other Intangible Assets (Allocation of Acquired Intangible Assets) (Details) - PitchBook [Member] $ in Millions	Dec. 01, 2016USD ($)
Business Acquisition [Line Items]
Intangible assets	$ 60.7
Weighted Average Useful Life (years)	6 years
Customer-related intangible assets [Member]
Business Acquisition [Line Items]
Intangible assets	$ 17.1
Weighted Average Useful Life (years)	10 years
Technology-based assets [Member]
Business Acquisition [Line Items]
Intangible assets	$ 40.8
Weighted Average Useful Life (years)	5 years
Intellectual property (trademarks and trade names) [Member]
Business Acquisition [Line Items]
Intangible assets	$ 2.8
Weighted Average Useful Life (years)	4 years

Acquisitions, Goodwill, and O_6

Acquisitions, Goodwill, and Other Intangible Assets (Schedule of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 564.9	$ 556.8
Foreign currency translation and adjustments to purchase price allocation		10.5
Other, primarily foreign currency translation	(8.2)
Goodwill, Ending Balance	$ 556.7	564.9
HelloWallet [Member]
Goodwill [Roll Forward]
Divestiture of HelloWallet		$ (2.4)

Acquisitions, Goodwill, and O_7

Acquisitions, Goodwill, and Other Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross	$ 313.3	$ 318.7
Accumulated Amortization	(239.4)	(223.3)
Net	$ 73.9	$ 95.4
Weighted Average Useful Life (years)	10 years	10 years
Intellectual property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 30.8	$ 31.5
Accumulated Amortization	(29.2)	(28.9)
Net	$ 1.6	$ 2.6
Weighted Average Useful Life (years)	9 years	9 years
Customer-related assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 153	$ 156.6
Accumulated Amortization	(111.7)	(108.1)
Net	$ 41.3	$ 48.5
Weighted Average Useful Life (years)	12 years	12 years
Supplier relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 0.2	$ 0.2
Accumulated Amortization	(0.1)	(0.1)
Net	$ 0.1	$ 0.1
Weighted Average Useful Life (years)	20 years	20 years
Technology-based assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 126.9	$ 127.9
Accumulated Amortization	(96.3)	(84.2)
Net	$ 30.6	$ 43.7
Weighted Average Useful Life (years)	7 years	7 years
Non-competition agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross	$ 2.4	$ 2.5
Accumulated Amortization	(2.1)	(2)
Net	$ 0.3	$ 0.5
Weighted Average Useful Life (years)	5 years	5 years

Acquisitions, Goodwill, and O_8

Acquisitions, Goodwill, and Other Intangible Assets (Amortization Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Acquisitions, Goodwill, and Other Intangible Assets [Abstract]
Amortization expense	$ 20.7	$ 23.6	$ 19.4
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,017	19.2
2,018	16.2
2,019	12.9
2,020	5
2,021	5
Thereafter	$ 15.6

Acquisitions, Goodwill, and O_9

Acquisitions, Goodwill, and Other Intangible Assets Acquisition, Goodwill, and Other Intangible Assets - Pro Forma (Details) - PitchBook [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenue	$ 834.1	$ 813.3
Operating income	157.7	170
Net income	$ 105.5	$ 117.1
Basic net income per share attributable to Morningstar, Inc. (in dollars per share)	$ 2.45	$ 2.65
Diluted net income per share attributable to Morningstar, Inc. (in dollars per share)	$ 2.44	$ 2.65

Divestitures (Narrative) (Detai

Divestitures (Narrative) (Details) - USD ($) $ in Millions	Jan. 01, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of a product line				$ 10.5	$ 0	$ 0
Gain on sale of a product line				$ 10.5	0	$ 0
Board Consulting Services Product Line | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of a product line	$ 10.5
Gain on sale of a product line	$ 10.5		$ 10.5
HelloWallet [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of a product line		$ 16.7			16.7
Proceeds from sale		23.7
Disposal group, goodwill		$ 2.4			$ 2.4

Divestitures (Amounts Included

Divestitures (Amounts Included in the Gain on Sale of Business (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total gain on sale of business		$ 10.5	$ 0	$ 0
HelloWallet [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds received			23.7
Intangibles and internally developed software			(4.5)
Goodwill	$ (2.4)		(2.4)
Other assets and liabilities			(0.1)
Total gain on sale of business	$ 16.7		$ 16.7

Investments in Unconsolidated_3

Investments in Unconsolidated Entities (Details) ¥ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2018JPY (¥)	Dec. 31, 2017JPY (¥)
Schedule of Equity Method Investments [Line Items]
Cost method investments	$ 3.2	$ 2.3
Total investments in unconsolidated entities	63.1	62
Cost-method investments, other than temporary impairment	0	0
Equity method investment, other than temporary impairment	0	0
Other Equity Method Investments [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	10.3	$ 12.6
YCharts [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		22.00%		22.00%
Morningstar Japan KK [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 23.9	$ 26.4
Equity method investment, ownership percentage	30.00%	34.00%	30.00%	34.00%
Equity method investment, approximate market value	$ 68.4	$ 94.6	¥ 7,525.4	¥ 10,649.6
Sustainalytics [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 25.7	$ 20.7
Equity method investment, ownership percentage	44.00%	40.00%	44.00%	40.00%
Ellevest [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17.00%		17.00%

Property, Equipment, and Capi_3

Property, Equipment, and Capitalized Software (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	$ 495.2	$ 432.1
Less accumulated depreciation	(351.7)	(284.7)
Property, equipment, and capitalized software, net	143.5	147.4
Depreciation expense	76	67.6	$ 51.3
Computer equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	83.5	81.6
Capitalized software [Member]
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	294.8	239.2
Tangible Asset Impairment Charges		4.1
Furniture and fixtures [Member]
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	29.6	27.6
Leasehold improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	77.3	72.5
Telephone equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	2.1	2.3
Construction in progress [Member]
Property, Plant and Equipment, Net [Abstract]
Property, equipment, and capitalized software, at cost	$ 7.9	$ 8.9

Operating Leases Operating Le_2

Operating Leases Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,012	$ 34.4
2,013	36
2,014	32.2
2,015	20.8
2,016	15.1
Thereafter	47.7
Total	186.2
Rent expense	32.5	$ 30.3	$ 26.3
Deferred rent	$ 28.6	$ 31.2

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Nov. 30, 2011	May 31, 2011	Dec. 31, 2018	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense			$ 42.1
Expected amortization period (months)			32 years
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period			10 years
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Unrecognized stock-based compensation expense			$ 36.9
Expected amortization period (months)			33 years
Performance share awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
2004 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted		86,106
Fair value per share (in dollars per share)				$ 23.81
2011 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted	6,095
Non-employee director [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Non-employee director [Member] | Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Employee [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years

Stock-Based Compensation (Share

Stock-Based Compensation (Shares Available for Future Grants) (Details) shares in Millions	Dec. 31, 2018shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares available for future grants	0

Stock-Based Compensation (Alloc

Stock-Based Compensation (Allocation of Stock-Based Compensation Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 31.7	$ 24.1	$ 14.5
Income tax benefit related to the stock-based compensation expense	7	7.8	4.3
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	19.8	16.5	14.6
Performance share awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	10.2	7.1	(0.1)
Market Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1.7	$ 0.5	$ 0

Stock-Based Compensation (Unrec

Stock-Based Compensation (Unrecognized Stock-Based Compensation Expense) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit related to the stock-based compensation expense	$ 42.1
Expected amortization period (months)	32 years
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit related to the stock-based compensation expense	$ 36.9
Expected amortization period (months)	33 years
Market Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit related to the stock-based compensation expense	$ 5.2
Expected amortization period (months)	28 years

Stock-Based Compensation (Restr

Stock-Based Compensation (Restricted Stock Units Activity) (Details) - Restricted stock units [Member] - $ / shares	12 Months Ended			36 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
RSUs Outstanding, Beginning Balance, Unvested	604,879	541,245	572,526	572,526
RSUs Outstanding, Beginning Balance, Vested but Deferred	3,279	9,748	14,924	14,924
RSUs Outstanding, Beginning Balance	608,158	550,993	587,450	587,450
RSUs Outstanding, Beginning Balance, Weighted Average Grant Date Value per RSU	$ 77.52	$ 75.77	$ 72.14	$ 72.14
Target performance share awards granted	243,614	331,470	241,609
Granted, Vested but Deferred	0	0	0
Granted	243,614	331,470	241,609
Granted, Weighted Average Grant Date Value per RSU	$ 108.60	$ 78.33	$ 77.82
Dividend equivalents, Unvested	0	0	370
Dividends equivalents, Vested but Deferred	16	78	136
Dividends equivalents	16	78	506
Dividends equivalents, Weighted Average Grant Date Value per RSU	$ 73.28	$ 60.99	$ 56.52
Vested, Unvested	(279,774)	(212,005)	(225,590)
Vested, Vested but Deferred	0	0	0
Vested	(279,774)	(212,005)	(225,590)
Vested, Weighted Average Grant Date Value per RSU	$ 80.68	$ 75.38	$ 69.39
Issued, Unvested	0	0	0
Issued, Vested but Deferred	(3,295)	(6,547)	(5,312)
Issued	(3,295)	(6,547)	(5,312)
Issued, Weighted Average Grant Date Value per RSU	$ 73.28	$ 49.40	$ 44.47
Forfeited, Unvested	(41,254)	(55,831)	(47,670)
Forfeited, Vested but Deferred	0	0	0
Forfeited	(41,254)	(55,831)	(47,670)
Forfeited, Weighted Average Grant Date Value per RSU	$ 86.47	$ 76.49	$ 74.45
RSUs Outstanding, Ending Balance, Unvested	527,465	604,879	541,245	527,465
RSUs Outstanding, Ending Balance, Vested but Deferred	0	3,279	9,748	0
RSUs Outstanding, Ending Balance	527,465	608,158	550,993	527,465
RSUs Outstanding, Ending Balance, Weighted Average Grant Date Value per RSU	$ 89.53	$ 77.52	$ 75.77	$ 89.53

Stock-Based Compensation (Perfo

Stock-Based Compensation (Performance Shares) (Details) - Performance share awards [Member] $ / shares in Units, $ in Millions	12 Months Ended	36 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2018USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance share awards granted		41,439
Granted, Weighted Average Grant Date Value per RSU | $ / shares	$ 81.71
Number of shares that will be issued based on final 2018 performance levels	0
Unamortized expense, based on current performance levels (in millions) | $	$ 0	$ 0

Stock-Based Compensation (Assum

Stock-Based Compensation (Assumptions Used to Estimate Fair Value of Market Units (Details) - Market Stock Units [Member]	Nov. 15, 2018	May 15, 2018	Nov. 15, 2017	May 15, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	19.60%	17.40%	17.70%	17.40%
Dividend yield	0.83%	0.89%	1.04%	1.20%
Risk-free interest rate	2.92%	2.70%	1.79%	1.49%

Stock-Based Compensation (Marke

Stock-Based Compensation (Market Units) (Details) - Market Stock Units [Member] $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market stock units granted (in shares)	84,153
Weighted average fair value per award (in dollars per share) | $ / shares	$ 89.58
Number of target market stock units outstanding (in shares)	81,274
Unamortized expense, based on current performance levels (in millions) | $	$ 5.2

Stock-Based Compensation (Ass_2

Stock-Based Compensation (Assumptions for Black-Scholes Option Pricing Model) (Details) - Stock options [Member]	12 Months Ended
	Dec. 31, 2014
Assumptions for Black-Scholes Option Pricing Model [Line Items]
Expected life (years):	7 years 4 months 24 days
Expected volatility	35.10%
Dividend yield	0.35%
Risk-free interest rate	2.87%

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Option exercise price grouping [Member]
Intrinsic Value of Options Exercised [Abstract]
Intrinsic value of options exercised	$ 0.1	$ 0.1	$ 0.1
Option grants excluding options granted at discount [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Balance, Options, Outstanding, Underlying Shares	41,685	46,001	52,096
Granted, Underlying Shares	0	0	0
Canceled, Underlying Shares	0	0	0
Exercised, Underlying Shares	(1,000)	(4,316)	(6,095)
Ending Balance, Options, Outstanding, Underlying Shares	40,685	41,685	46,001
Options, Weighted Average Exercise Price [Abstract]
Beginning Balance, Options, Outstanding, Weighted Average Exercise Price	$ 57.28	$ 57.28	$ 57.52
Granted, Weighted Average Exercise Price	0	0	0
Canceled, Weighted Average Exercise Price	0	0	0
Exercised, Weighted Average Exercise Price	57.28	57.28	59.35
Ending Balance, Options, Outstanding, Weighted Average Exercise Price	$ 57.28	$ 57.28	$ 57.28
Options, Exercisable, Number of Shares and Weighted Average Exercise Price [Abstract]
Options exercisable - end of year, Underlying Shares	40,685	41,685	46,001
Options exercisable - end of year, Weighted Average Exercise Price	$ 57.28	$ 57.28	$ 57.28

Stock-Based Compensation (Addit

Stock-Based Compensation (Additional Information on Options) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Closing Stock Price Used to Calculate Intrinsic Value	$ 109.84
Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices	57.28
Exercise price range, lower range limit	$ 57.28
Exercise price range, upper range limit	$ 59.35
Options Outstanding, Number of Options | shares	40,685
Options Outstanding, Weighted Average Remaining Contractual Life (years)	2 years 4 months 13 days
Options Outstanding, Weighted Average Exercise Price	$ 57.28
Options Outstanding, Aggregate Intrinsic Value | $	$ 2.1
Options Exercisable, Exercisable Shares | shares	40,685
Options Exercisable, Weighted Average Remaining Contractual Life (years)	2 years 4 months 13 days
Options Exercisable, Weighted Average Exercise Price	$ 57.28
Options Exercisable, Aggregate Intrinsic Value | $	$ 2.1
Share Based Compensation, Arrangement By Share Based Payments, Vested or Expected to Vest, Range of Exercise Prices	57.28
Option Outstanding, Number of Options, Vested or Expected to Vest | shares	40,685
Options Outstanding, Weighted Average Remaining Contractual Life (years), Vested or Expected to vest	2 years 4 months 13 days
Options Outstanding, Weighted Average Exercise Price, Vested or Expected to Vest	$ 57.28
Options Outstanding, Average Intrinsic Value, Vested or Expected to Vest | $	$ 2.1

Stock-Based Compensation (Total

Stock-Based Compensation (Total Stock-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 31.7	$ 24.1	$ 14.5
Cost of revenue [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	11.7	9.6	7.5
Selling and marketing expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	3.5	3	1.9
General and administrative expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 16.5	$ 11.5	$ 5.1

Stock-based Compensation (Pitch

Stock-based Compensation (PitchBook Bonus Plan) (Details) - Performance share awards [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended	36 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Target performance share awards granted			41,439
Number of shares that will be issued based on final 2018 performance levels	0
Unamortized expense, based on current performance levels (in millions)	$ 0		$ 0
PitchBook Plan, For 2017 To 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance, aggregate target value	30		30
Target value of shares expected to be granted in year one	7.5		7.5
Target value of shares expected to be granted in year two	7.5		7.5
Target value of shares expected to be granted in year three	15		15
PitchBook Plan, Renewal For 2020 To 2022 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance, aggregate target value	30		30
Target value of shares expected to be granted in year one	7.5		7.5
Target value of shares expected to be granted in year two	7.5		7.5
Target value of shares expected to be granted in year three	$ 15		$ 15
PitchBook Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Shares of common stock to be issued for each equity instrument	1		1
Weighted average fair value per award	$ 95.53		$ 95.53
Unamortized expense, based on current performance levels (in millions)	$ 0		$ 0
Forecast [Member] | PitchBook Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance share awards granted		77,716
Number of shares that will be issued based on final 2018 performance levels		106,854

Defined Contribution Plan (Deta

Defined Contribution Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan [Abstract]
401(k) matching contributions	$ 11,000,000	$ 10,400,000	$ 9,000,000
Matching contribution to 401(k) for every dollar	$ 0.75	$ 0.75	$ 0.75
Matching contribution percent to employee's contribution in pay period	7.00%	7.00%	7.00%

Income Taxes (Schedule of Incom

Income Taxes (Schedule of Income Tax Expense and Effective Tax Rate) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income before income taxes and equity in net income (loss) of unconsolidated entities	$ 48.4	$ 72.7	$ 55	$ 56.8	$ 41.9	$ 50.8	$ 61.3	$ 27.1	$ 232.9	$ 181.1	$ 224.9
Equity in net income (loss) of unconsolidated entities	(0.5)	0.3	(0.4)	(1.5)	(0.3)	0	(0.2)	(0.8)	(2.1)	(1.3)	(0.2)
Income loss from continuing operations before income taxes domestic and foreign									230.8	179.8	224.7
Income tax expense	$ 5.5	$ 16.1	$ 12.8	$ 13.4	$ 2.7	$ 16.9	$ 15	$ 8.3	$ 47.8	$ 42.9	$ 63.7
Effective income tax rate									20.70%	23.90%	28.30%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Discrete net tax benefit recognized						$ (10.6)
Provisional tax benefit, Tax Reform Act					$ 14.7
Provisional tax charge on deemed mandatory repatriation of foreign earnings, Tax Reform Act			$ 7.5		7.5
Reduction of deferred tax liabilities for foreign equity method investments, Tax Reform Act						6.4
Provisional estimate of deferred taxes for foreign withholding taxes, Tax Reform Act			3		3	3
Accumulated undistributed earnings from foreign subsidiaries			209.2		209.2
Unrecognized tax benefits included in current liabilities			6.6		6.6	8.7
Unrecognized tax benefits included in non-current liabilities			7.1		7.1	7
Unrecognized tax benefits, period increase (decrease)					2.1
Result of tax position taken during period					2.1
Increase in income tax expense					2.1
Reductions resulting from settlements and lapse of statute of limitations					7.7
Decrease of unrecognized tax benefits relating to settlements with tax authorities					1.5
Reductions resulting from settlements and lapse statute of limitations, tax effect			1.4		1.4
Decreases relating to settlements with tax authorities		$ 2.4			2.5	0
Reductions as a result of lapse of the applicable statute of limitations			1.9	$ 3.4	5.2	2.6
Gross unrecognized tax benefits			13.1		13.1	18.7	$ 18.4
Unrecognized tax benefits that would impact effective tax rate			13.1		13.1
Decrease in income tax expense upon recognition of gross unrecognized tax benefits			12.6		12.6
Forecast [Member]
Income Tax Contingency [Line Items]
Foreign earnings repatriated	$ 45.8
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards			10.6		10.6	14.8
Operating loss carryforwards, not subject to valuation allowances			2		2	5.4
Subject to Expiration Date [Member] | Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards			1		1	9.1
Subject to Expiration Date [Member] | Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards			$ 5.5		$ 5.5	$ 5.7

Income Taxes (Schedule of Effec

Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Examination [Line Items]
Income tax expense at U.S. federal rate									$ 48.5	$ 63	$ 78.6
Income tax expense at U.S. federal rate, percent									21.00%	35.00%	35.00%
State income taxes, net of federal income tax benefit									$ 7.4	$ 3	$ 4.5
State income taxes, net of federal income tax benefit, percent									3.20%	1.70%	2.00%
Change in U.S. tax rate									$ (0.6)	$ (14.7)	$ 0
Change in U.S. tax rate, percent									(0.30%)	(8.20%)	0.00%
Deemed mandatory repatriation									$ (1.2)	$ 7.5	$ 0
Deemed mandatory repatriation, percent									(0.50%)	4.20%	0.00%
Reduction of deferred tax liabilities for foreign equity method investments									$ (0.5)	$ (6.4)	$ 0
Reduction of deferred tax liabilities for foreign equity method investments, percent									(0.20%)	(3.60%)	(0.00%)
Withholding tax - repatriation									$ 0	$ 3	$ 0
Withholding tax - repatriation, percent									0.00%	1.70%	0.00%
Stock-based compensation activity									$ (2.6)	$ 0.3	$ (0.6)
Stock-based compensation activity, percent									(1.10%)	0.20%	(0.30%)
Equity in net income of unconsolidated subsidiaries (including holding gains upon acquisition)									$ 1	$ 1.2	$ (12.1)
Holding gain upon acquisition of additional ownership of equity method investments, percent									0.40%	0.70%	(5.40%)
Book gain over tax gain on sale of HelloWallet									$ 0	$ (6.8)	$ 0
Book gain over tax gain on sale of HelloWallet, percent									0.00%	(3.80%)	0.00%
Net change in valuation allowance related to non-U.S. deffered tax assets, primarily net operating losses									$ (0.2)	$ 0.1	$ (0.1)
Net change in valuation allowance related to non-U.S. deffered tax assets, primarily net operating losses, percent									(0.10%)	0.10%	0.00%
Difference between U.S. federal statutory and foreign tax rates									$ 0.2	$ (5.2)	$ (5.3)
Difference between U.S. federal statutory and foreign tax rates, percent									0.10%	(2.90%)	(2.40%)
Change in unrecognized tax benefits									$ 1	$ 1.2	$ 2.6
Changes in unrecognized tax benefits, percent									0.40%	0.70%	1.20%
Other tax credits									$ (3.6)	$ (3.7)	$ (3.7)
Other tax credits, percent									(1.60%)	(2.10%)	(1.60%)
GILTI tax									$ 1.4	$ 0	$ 0
GILTI tax, percent									0.60%	(0.00%)	(0.00%)
FDII deduction									$ (5.1)	$ 0	$ 0
FDII deduction, percent									(2.20%)	0.00%	0.00%
Other - net									$ 2.1	$ 0.4	$ (0.2)
Other - net, percent									0.90%	0.20%	(0.10%)
Income tax expense	$ 5.5	$ 16.1	$ 12.8	$ 13.4	$ 2.7	$ 16.9	$ 15	$ 8.3	$ 47.8	$ 42.9	$ 63.7
Income tax expense, percent									20.70%	23.90%	28.30%

Income Taxes (Schedule of Compo

Income Taxes (Schedule of Components of Income Tax Expense) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal									$ 31	$ 40.3	$ 42.8
State									11.1	6.6	6.5
Non-U.S.									12.3	9.9	9.7
Current tax expense									54.4	56.8	59
Federal									(3)	(10.9)	5.1
State									(1.7)	(1.9)	0.4
Non-U.S.									(1.9)	(1.1)	(0.8)
Deferred tax expense (benefit)									(6.6)	(13.9)	4.7
Income tax expense	$ 5.5	$ 16.1	$ 12.8	$ 13.4	$ 2.7	$ 16.9	$ 15	$ 8.3	$ 47.8	$ 42.9	$ 63.7

Income Taxes (Schedule of Inc_2

Income Taxes (Schedule of Income before Income Taxes and Equity in Net Income of Unconsolidated Entities) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S.									$ 188.2	$ 143.5	$ 186.5
Non-U.S.									44.7	37.6	38.4
Income before income taxes and equity in net loss of unconsolidated entities	$ 48.4	$ 72.7	$ 55	$ 56.8	$ 41.9	$ 50.8	$ 61.3	$ 27.1	$ 232.9	$ 181.1	$ 224.9

Income Taxes (Schedule of Defer

Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Stock-based compensation expense	$ 4.7	$ 3.7
Accrued liabilities	17	14.2
Deferred revenue	3.7	3.5
Net operating loss carryforwards - U.S.	0.2	1.9
Net operating loss carryforwards - Non-U.S.	2.4	3.1
Credits and incentive carryforwards	0	0.3
Deferred royalty revenue	0.3	0.2
Allowance for doubtful accounts	1.4	1.1
Deferred rent	7.4	6.2
Unrealized exchange losses, net	0.2	0
Other	0.6	0.3
Total deferred tax assets	37.9	34.5
Deferred tax liabilities:
Acquired intangible assets	(16.5)	(18.6)
Property, equipment and capitalized software	(26.7)	(24.6)
Unrealized exchange gains, net	0	(0.6)
Prepaid expenses	(7.1)	(3.9)
Investments in unconsolidated entities	(4.8)	(5.4)
Withholding tax - foreign dividends	(3)	(3)
Total deferred tax liabilities	58.1	56.1
Net deferred tax liability before valuation allowance	20.2	21.6
Valuation allowance	(2)	(2)
Total deferred tax liabilities	$ (22.2)	$ (23.6)

Income Taxes (Schedule of Def_2

Income Taxes (Schedule of Deferred Tax Assets and Liabilities Included in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Deferred tax liability, net	$ (22.2)	$ (23.6)

Income Taxes (Summary of Operat

Income Taxes (Summary of Operating Loss Carryforwards - U.S and Non-U.S) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Non-U.S. [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 10.6	$ 14.8
Operating loss carryforwards, not subject to valuation allowances	2	5.4
Non-U.S. [Member] | Subject to Expiration Date [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	5.5	5.7
Non-U.S. [Member] | No Expiration Date [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	5.1	9.1
U.S [Member] | Subject to Expiration Date [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 1	$ 9.1

Income Taxes (Accounting for Un

Income Taxes (Accounting for Uncertainty in Tax Positions) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits - beginning of the year	$ 18.7			$ 18.7	$ 18.4
Increases as a resulting of tax positions taken during a prior-year period				0.8	1.4
Decreases as a result of tax positions taken during a prior-year period				(0.3)	(0.4)
Increases as a result of tax positions taken during the current period				1.6	1.9
Decreases relating to settlements with tax authorities	$ (2.4)			(2.5)	0
Reductions as a result of lapse of the applicable statute of limitations		$ (1.9)	$ (3.4)	(5.2)	(2.6)
Gross unrecognized tax benefits - end of the year		$ 13.1		$ 13.1	$ 18.7

Income Taxes (Summary of Income

Income Taxes (Summary of Income Tax Examinations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Liabilities for interest and penalties	$ 1.3	$ 1.7

Share Repurchase Program (Detai

Share Repurchase Program (Details)	Dec. 31, 2018USD ($)shares
Equity [Abstract]
Stock repurchase program, authorized amount	$ 500,000,000
Shares repurchased, program life to date, shares | shares	202,245
Shares repurchased, program life to date, value	$ 20,900,000
Stock repurchase program, remaining authorized repurchase amount	$ 479,100,000

Recently Issued Accounting Pr_3

Recently Issued Accounting Pronouncements (Impact on Financial Statements, Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue from contracts	$ 1,019.9	$ 911.7	$ 798.6
Cumulative effect adjustment of new accounting principle				$ 17
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment of new accounting principle				$ 17
ASU 2014-09 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment of new accounting principle		$ 17
ASU 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue from contracts	$ 6.7

Recently Issued Accounting Pr_4

Recently Issued Accounting Pronouncements (Cumulative Effect of Changes from Adoption of Topic 606) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Deferred commissions, current and non-current	$ 25.1	$ 22.7	$ 22.7
Liabilities:
Deferred income tax liability		5.7
Equity:
Retained earnings	1,114.8	17	958.7
Balances without adoption of Topic 606
Assets
Deferred commissions, current and non-current	0		0
Liabilities:
Deferred income tax liability			0
Equity:
Retained earnings			$ 0
Adjustments due to Topic 606
Assets
Deferred commissions, current and non-current	$ 25.1
Adjustments due to Topic 606 | ASU 2014-09
Assets
Deferred commissions, current and non-current		22.7
Liabilities:
Deferred income tax liability		5.7
Equity:
Retained earnings		$ 17

Recently Issued Accounting Pr_5

Recently Issued Accounting Pronouncements (Impact of Adoption of Topic 606) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Balance Sheet:
Accounts receivable, less allowance for doubtful accounts	$ 172.2				$ 148.2				$ 172.2	$ 148.2
Deferred commissions, current and non-current	25.1				22.7				25.1	22.7		$ 22.7
Deferred revenue, current and non-current	210								210
Income Statement:
Revenue	262.7	$ 261.3	$ 252.4	$ 243.5	243.1	$ 229.9	$ 229.2	$ 209.5	1,019.9	911.7	$ 798.6
Cost of revenue									411.1	386.6	344.3
Sales and marketing									148.5	134.3	97.6
Operating income	49.3	65.4	$ 53.6	$ 47.5	42.6	$ 52.8	$ 46	$ 28.4	215.8	169.8	$ 180.8
Impact of adopting Topic 606
Balance Sheet:
Accounts receivable, less allowance for doubtful accounts		0
Deferred commissions, current and non-current	25.1								25.1
Deferred revenue, current and non-current		$ 0
Impact of adopting Topic 606 | ASU 2014-09
Balance Sheet:
Deferred commissions, current and non-current												$ 22.7
Income Statement:
Revenue									6.7
Cost of revenue									6.7
Sales and marketing									2.9
Operating income									(2.9)
Balances without adoption of Topic 606
Balance Sheet:
Accounts receivable, less allowance for doubtful accounts	172.2								172.2
Deferred commissions, current and non-current	0				$ 0				0	$ 0
Deferred revenue, current and non-current	$ 210								210
Income Statement:
Revenue									1,013.2
Cost of revenue									404.4
Sales and marketing									151.4
Operating income									$ 212.9

Selected Quarterly Financial _3

Selected Quarterly Financial Data - Schedule of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jan. 01, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue		$ 262.7	$ 261.3	$ 252.4	$ 243.5	$ 243.1	$ 229.9	$ 229.2	$ 209.5	$ 1,019.9	$ 911.7	$ 798.6
Total operating expense		213.4	195.9	198.8	196	200.5	177.1	183.2	181.1	804.1	741.9	617.8
Operating income		49.3	65.4	53.6	47.5	42.6	52.8	46	28.4	215.8	169.8	180.8
Non-operating income (expense), net		(0.9)	7.3	1.4	9.3	(0.7)	(2)	15.3	(1.3)	17.1	11.3	44.1
Income before income taxes and equity in net income (loss) of unconsolidated entities		48.4	72.7	55	56.8	41.9	50.8	61.3	27.1	232.9	181.1	224.9
Equity in net income (loss) of unconsolidated entities		(0.5)	0.3	(0.4)	(1.5)	(0.3)	0	(0.2)	(0.8)	(2.1)	(1.3)	(0.2)
Income tax expense		5.5	16.1	12.8	13.4	2.7	16.9	15	8.3	47.8	42.9	63.7
Consolidated net income		$ 42.4	$ 56.9	$ 41.8	$ 41.9	$ 38.9	$ 33.9	$ 46.1	$ 18	$ 183	$ 136.9	$ 161
Earnings Per Share, Basic and Diluted [Abstract]
Basic (in dollars per share)		$ 0.99	$ 1.33	$ 0.98	$ 0.99	$ 0.91	$ 0.80	$ 1.07	$ 0.42
Diluted (in dollars per share)		0.99	1.32	0.97	0.98	0.91	0.79	1.07	0.42
Dividends Per Common Share: [Abstract]
Common stock, dividends, per share, declared (in dollars per share)		0.53	0	0.25	0.25	0.48	0	0.23	0.23	$ 1.03	$ 0.94	$ 0.89
Dividends paid per common share (in dollars per share)		$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.23	$ 0.23	$ 0.23	$ 0.23	$ 1	$ 0.92	$ 0.88
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average common shares outstanding - basic (in shares)		42.7	42.6	42.6	42.5	42.5	42.5	42.9	42.9	42.6	42.7	43
Weighted average common shares outstanding - diluted (in shares)		43.1	43.1	43	42.9	42.9	42.8	43.1	43.2	43	43	43.3
Revenue benefit from amended license agreement			$ 10.5
Holding gain upon acquisition of additional ownership of equity-method investments						$ 17.5				$ 0	$ 0	$ 37.1
Gain on sale of a product line										$ 10.5	0	$ 0
Income tax benefit related to the impact of the Tax Reform Act											$ 10.6
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Board Consulting Services Product Line
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Gain on sale of a product line	$ 10.5				$ 10.5