Northern Trust (NTRS) 10-Q 27 Oct 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page	9 Months Ended
	Sep. 30, 2020shares
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-36609
Entity Registrant Name	NORTHERN TRUST CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-2723087
Entity Address, Address Line One	50 South LaSalle Street
Entity Address, City or Town	Chicago,
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60603
City Area Code	312
Local Phone Number	630-6000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)	208,121,233
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000073124
Current Fiscal Year End Date	--12-31
Common Stock, $1.66 2/3 Par Value
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, $1.66 2/3 Par Value
Trading Symbol	NTRS
Security Exchange Name	NASDAQ
Depositary Shares, each representing 1/1,000th interest in a share of Series E Non-Cumulative Perpetual Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing 1/1,000th interest in a share of Series E Non-Cumulative Perpetual Preferred Stock
Trading Symbol	NTRSO
Security Exchange Name	NASDAQ

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
ASSETS
Cash and Due from Banks	$ 4,737.5	$ 4,459.2
Federal Reserve and Other Central Bank Deposits	39,244.6	33,886
Interest-Bearing Deposits with Banks	2,754.4	4,877.1
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,533.4	712.8
Debt Securities
Available for Sale (Amortized cost of $41,659.2 and $38,722.2)	42,551	38,876.3
Held to Maturity	16,754	12,284.5
Trading Account	0.6	0.3
Total Debt Securities	59,305.6	51,161.1
Loans and Leases
Loans and leases	32,766.3	31,409.6
Allowance for Credit Losses	(223)	(104.5)
Buildings and Equipment	510	483.3
Client Security Settlement Receivables	2,296.8	845.7
Goodwill	698	696.8
Other Assets	8,458.4	8,401.3
Total Assets	152,082	136,828.4
Deposits
Demand and Other Noninterest-Bearing	16,358.5	14,114.7
Savings, Money Market and Other Interest-Bearing	25,379.1	21,441.5
Savings Certificates and Other Time	1,486.7	986.7
Non U.S. Offices — Noninterest-Bearing	18,019.2	12,177.4
Non U.S. Offices — Interest-Bearing	61,345.6	60,400.3
Total Deposits	122,589.1	109,120.6
Federal Funds Purchased	2,203.7	552.9
Securities Sold Under Agreements to Repurchase	269.8	489.7
Other Borrowings	5,771.7	6,744.8
Senior Notes	3,655.6	2,573
Long-Term Debt	1,196	1,148.1
Floating Rate Capital Debt	277.7	277.7
Other Liabilities	4,539.3	4,830.6
Total Liabilities	140,502.9	125,737.4
STOCKHOLDERS' EQUITY
Common Stock	408.6	408.6
Additional Paid-In Capital	961.8	1,013.1
Retained Earnings	12,118.3	11,656.7
Accumulated Other Comprehensive Income (Loss)	424.5	(194.7)
Treasury Stock	(3,219)	(3,066.1)
Total Stockholders’ Equity	11,579.1	11,091
Total Liabilities and Stockholders’ Equity	$ 152,082	$ 136,828.4
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 1.6667	$ 1.6667
Common stock, authorized (in shares)	560,000,000	560,000,000
Series C Preferred Stock
STOCKHOLDERS' EQUITY
Preferred Stock	$ 0	$ 388.5
Preferred stock, outstanding (in shares)	0	16,000
Series D Preferred Stock
STOCKHOLDERS' EQUITY
Preferred Stock	$ 493.5	$ 493.5
Total Stockholders’ Equity	$ 493.5	$ 493.5
Preferred stock, outstanding (in shares)	5,000	5,000
Series E Preferred Stock
STOCKHOLDERS' EQUITY
Preferred Stock	$ 391.4	$ 391.4
Total Stockholders’ Equity	$ 391.4	$ 391.4
Preferred stock, par value (in dollars per share)	$ 0
Preferred stock, outstanding (in shares)	16,000	16,000
Commercial
Loans and Leases
Loans and leases	$ 14,581.7	$ 14,001.3
Personal
Loans and Leases
Loans and leases	$ 18,184.6	$ 17,408.3

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale securities, amortized cost	$ 41,659.2	$ 38,722.2
Unearned income	14.6	14.1
Held to maturity, fair value	$ 16,746.5	$ 12,249.3
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 1.6667	$ 1.6667
Common stock, authorized (in shares)	560,000,000	560,000,000
Common stock, outstanding (in shares)	208,121,233	209,709,046
Treasury stock (in shares)	37,050,291	35,462,478
Series C Preferred Stock
Preferred stock, outstanding (in shares)	0	16,000
Series D Preferred Stock
Preferred stock, outstanding (in shares)	5,000	5,000
Series E Preferred Stock
Preferred stock, outstanding (in shares)	16,000	16,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Noninterest Income
Trust, Investment and Other Servicing Fees	$ 1,003.8	$ 975.5	$ 2,968.9	$ 2,859.9
Foreign Exchange Trading Income	61.6	59.7	221.8	186.4
Treasury Management Fees	11.6	11.2	34	34.1
Security Commissions and Trading Income	26	29.1	100.9	75.8
Other Operating Income	53.5	45.1	144.4	113
Investment Security Gains (Losses), net (Note)	0	(0.4)	0.1	(0.9)
Total Noninterest Income	1,156.5	1,120.2	3,470.1	3,268.3
Net Interest Income
Interest Income	355.4	620.8	1,290.9	1,923.8
Interest Expense	26.8	203.1	182.1	666.7
Net Interest Income	328.6	417.7	1,108.8	1,257.1
Provision for Credit Losses	0.5	(7)	127.5	(13.5)
Net Interest Income after Provision for Credit Losses	328.1	424.7	981.3	1,270.6
Noninterest Expense
Compensation	461.7	458	1,421.8	1,395.5
Employee Benefits	97.5	87.6	285.8	262.6
Outside Services	186	194	555	568.8
Equipment and Software	170.7	151.7	497.1	447.2
Occupancy	51.8	53	162.9	155.5
Other Operating Expense	127	92	274.6	241.6
Total Noninterest Expense	1,094.7	1,036.3	3,197.2	3,071.2
Income before Income Taxes	389.9	508.6	1,254.2	1,467.7
Provision for Income Taxes	95.4	124	285.8	346.6
Net Income	294.5	384.6	968.4	1,121.1
Preferred Stock Dividends	16.2	17.4	51.5	40.6
Net Income Applicable to Common Stock	$ 278.3	$ 367.2	$ 916.9	$ 1,080.5
Per Common Share
Net Income — Basic (in dollars per share)	$ 1.32	$ 1.70	$ 4.35	$ 4.95
Net Income - Diluted (in dollars per share)	$ 1.32	$ 1.69	$ 4.34	$ 4.92
Average number of common shares outstanding
Average Number of Common Shares Outstanding - Basic (in shares)	208,106,190	213,176,809	208,351,088	215,832,347
Average Number of Common Shares Outstanding - Diluted (in shares)	208,688,494	214,206,576	209,023,331	216,863,563
Note: Changes in Other-Than-Temporary-Impairment (OTTI) Losses prior to the adoption of ASU 2016-13	$ 0	$ (0.1)	$ 0	$ (0.3)
Other Security Gains (Losses), net	0	(0.3)	0.1	(0.6)
Investment Security Gains (Losses), net	$ 0	$ (0.4)	$ 0.1	$ (0.9)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net Income	$ 294.5	$ 384.6	$ 968.4	$ 1,121.1
Other Comprehensive Income (Loss) (Net of Tax and Reclassifications)
Net Unrealized Gains on Debt Securities Available for Sale	33.5	57	551.3	305
Net Unrealized Gains (Losses) on Cash Flow Hedges	1.3	(2.4)	5.3	(1.9)
Net Foreign Currency Adjustments	1.8	9.9	29.5	38.8
Net Pension and Other Postretirement Benefit Adjustments	17.5	4.3	33.1	20.8
Net Change	54.1	68.8	619.2	362.7
Comprehensive Income	$ 348.6	$ 453.4	$ 1,587.6	$ 1,483.8

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect Adjustment	Adjusted Balance	PREFERRED STOCK	PREFERRED STOCKAdjusted Balance	COMMON STOCK	COMMON STOCKAdjusted Balance	ADDITIONAL PAID-IN CAPITAL	ADDITIONAL PAID-IN CAPITALAdjusted Balance	RETAINED EARNINGS	RETAINED EARNINGSCumulative Effect Adjustment	RETAINED EARNINGSAdjusted Balance	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)Adjusted Balance	TREASURY STOCK	TREASURY STOCKAdjusted Balance
Beginning balance at Dec. 31, 2018	$ 10,508.3			$ 882		$ 408.6		$ 1,068.5		$ 10,776.8			$ (453.7)		$ (2,173.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	347.1									347.1
Net Change	108.4												108.4
Dividends [Abstract]
Common Stock	(133.7)									(133.7)
Preferred Stock	(17.3)									(17.3)
Stock Awards and Options Exercised	60.8							(65.2)							126
Stock Purchased	(257.4)														(257.4)
Ending balance at Mar. 31, 2019	10,616.2			882		408.6		1,003.3		10,972.9			(345.3)		(2,305.3)
Beginning balance at Dec. 31, 2018	10,508.3			882		408.6		1,068.5		10,776.8			(453.7)		(2,173.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,121.1
Net Change	362.7
Ending balance at Sep. 30, 2019	10,811.3			882		408.6		1,009.7		11,441.2			(91)		(2,839.2)
Beginning balance at Mar. 31, 2019	10,616.2			882		408.6		1,003.3		10,972.9			(345.3)		(2,305.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	389.4									389.4
Net Change	185.5												185.5
Dividends [Abstract]
Common Stock	(130.9)									(130.9)
Preferred Stock	(5.9)									(5.9)
Stock Awards and Options Exercised	22.4							10.5							11.9
Stock Purchased	(271.2)														(271.2)
Ending balance at Jun. 30, 2019	10,805.5			882		408.6		1,013.8		11,225.5			(159.8)		(2,564.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	384.6									384.6
Net Change	68.8												68.8
Dividends [Abstract]
Common Stock	(151.5)									(151.5)
Preferred Stock	(17.4)									(17.4)
Stock Awards and Options Exercised	28.5							(4.1)							32.6
Stock Purchased	(307.2)														(307.2)
Ending balance at Sep. 30, 2019	10,811.3			882		408.6		1,009.7		11,441.2			(91)		(2,839.2)
Beginning balance at Dec. 31, 2019	11,091	$ (10.1)	$ 11,080.9	1,273.4	$ 1,273.4	408.6	$ 408.6	1,013.1	$ 1,013.1	11,656.7	$ (10.1)	$ 11,646.6	(194.7)	$ (194.7)	(3,066.1)	$ (3,066.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	360.6									360.6
Net Change	239.7												239.7
Dividends [Abstract]
Common Stock	(148.6)									(148.6)
Preferred Stock	(19)									(19)
Redemption of Preferred Stock, Series C	(400)			(388.5)						(11.5)
Stock Awards and Options Exercised	62.9							(74.8)							137.7
Stock Purchased	(296.8)														(296.8)
Ending balance at Mar. 31, 2020	10,879.7			884.9		408.6		938.3		11,828.1			45		(3,225.2)
Beginning balance at Dec. 31, 2019	11,091	$ (10.1)	$ 11,080.9	1,273.4	$ 1,273.4	408.6	$ 408.6	1,013.1	$ 1,013.1	11,656.7	$ (10.1)	$ 11,646.6	(194.7)	$ (194.7)	(3,066.1)	$ (3,066.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	968.4
Net Change	619.2
Dividends [Abstract]
Stock Purchased	(298.5)
Ending balance at Sep. 30, 2020	11,579.1			884.9		408.6		961.8		12,118.3			424.5		(3,219)
Beginning balance at Mar. 31, 2020	10,879.7			884.9		408.6		938.3		11,828.1			45		(3,225.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	313.3									313.3
Net Change	325.4												325.4
Dividends [Abstract]
Common Stock	(148.2)									(148.2)
Preferred Stock	(4.8)									(4.8)
Stock Awards and Options Exercised	17							13.2							3.8
Stock Purchased	(0.2)														(0.2)
Ending balance at Jun. 30, 2020	11,382.2			884.9		408.6		951.5		11,988.4			370.4		(3,221.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	294.5									294.5
Net Change	54.1												54.1
Dividends [Abstract]
Common Stock	(148.4)									(148.4)
Preferred Stock	(16.2)									(16.2)
Stock Awards and Options Exercised	14.4							10.3							4.1
Stock Purchased	(1.5)														(1.5)
Ending balance at Sep. 30, 2020	$ 11,579.1			$ 884.9		$ 408.6		$ 961.8		$ 12,118.3			$ 424.5		$ (3,219)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Common stock dividends (in usd per share)	$ 0.70	$ 0.70	$ 0.70	$ 0.70	$ 0.60	$ 0.60

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$ 968.4	$ 1,121.1
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Investment Security (Losses) Gains, net	(0.1)	0.9
Amortization and Accretion of Securities and Unearned Income, net	63.3	51.7
Provision for Credit Losses	127.5	(13.5)
Depreciation on Buildings and Equipment	85.9	76.5
Amortization of Computer Software	274	252.6
Amortization of Intangibles	12.6	12.5
Pension Plan Contributions	(10.6)	(3)
Change in Receivables	47.6	(328.6)
Change in Interest Payable	(5)	(9.2)
Change in Collateral With Derivative Counterparties, net	(937.2)	39.8
Other Operating Activities, net	(205.9)	(245.2)
Net Cash Provided by Operating Activities	420.5	955.6
CASH FLOWS FROM INVESTING ACTIVITIES
Net Change in Federal Funds Sold and Securities Purchased under Agreements to Resell	(717.9)	616.3
Change in Interest-Bearing Deposits with Banks	2,194.9	198.3
Net Change in Federal Reserve and Other Central Bank Deposits	(4,592.3)	7,032.2
Purchases of Debt Securities – Held to Maturity	(28,474)	(9,862)
Proceeds from Maturity and Redemption of Debt Securities – Held to Maturity	23,901.2	12,448.2
Purchases of Debt Securities – Available for Sale	(8,558.6)	(8,644.3)
Proceeds from Sale, Maturity and Redemption of Debt Securities – Available for Sale	5,761.9	6,910
Change in Loans and Leases	(1,339.6)	1,636.9
Purchases of Buildings and Equipment	(102.6)	(49.8)
Purchases and Development of Computer Software	(287.5)	(304.7)
Change in Client Security Settlement Receivables	(1,377.3)	(465.1)
Payments to Acquire Interest in Subsidiaries and Affiliates	0	(10.5)
Bank-Owned Life Insurance Policy Premiums	0	(1,000)
Other Investing Activities, net	477.3	492.9
Net Cash (Used in) Provided by Investing Activities	(13,114.5)	8,998.4
CASH FLOWS FROM FINANCING ACTIVITIES
Change in Deposits	12,697.8	(6,355.5)
Change In Federal Funds Purchased	1,650.8	(2,393.7)
Change in Securities Sold under Agreements to Repurchase	(219.9)	96.9
Change in Short-Term Other Borrowings	(934)	(118.7)
Redemption of Preferred Stock - Series C	(400)	0
Proceeds from Senior Notes	993.2	498
Treasury Stock Purchased	(298.5)	(835.8)
Net Proceeds from Stock Options	10.7	19.9
Cash Dividends Paid on Common Stock	(438.8)	(381)
Cash Dividends Paid on Preferred Stock	(29.7)	(29.1)
Other Financing Activities, net	0.7	0.1
Net Cash Provided by (Used in) Financing Activities	13,032.3	(9,498.9)
Effect of Foreign Currency Exchange Rates on Cash	(60)	0.9
Change in Cash and Due from Banks	278.3	456
Cash and Due from Banks at Beginning of Year	4,459.2	4,581.6
Cash and Due from Banks at End of Year	4,737.5	5,037.6
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest Paid	190.3	675.9
Income Taxes Paid	264.5	360.3
Transfers from Loans to OREO	0.2	2.6
Transfers from Debt Securities Available for Sale to Debt Securities Held to Maturity	$ 301.5	$ 0

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe consolidated financial statements include the accounts of Northern Trust Corporation (Corporation) and its wholly-owned subsidiary, The Northern Trust Company (Bank), and various other wholly-owned subsidiaries of the Corporation and Bank. Throughout the notes to the consolidated financial statements, the term “Northern Trust” refers to the Corporation and its subsidiaries. Intercompany balances and transactions have been eliminated in consolidation. The consolidated financial statements, as of and for the periods ended September 30, 2020 and 2019, have not been audited by the Corporation’s independent registered public accounting firm. In the opinion of management, all accounting entries and adjustments, including normal recurring accruals, necessary for a fair presentation of the financial position and the results of operations for the interim periods have been made. The accounting and financial reporting policies of Northern Trust conform to U.S. generally accepted accounting principles (GAAP) and reporting practices prescribed for the banking industry. The consolidated statements of income include results of acquired subsidiaries from the dates of acquisition. Certain prior-period balances have been reclassified to conform with the current year’s presentation. For a description of Northern Trust’s significant accounting policies, refer to Note 1 — Summary of Significant Accounting Policies included under Item 8. Financial Statements and Supplementary Data in the Annual Report on Form 10-K for the year ended December 31, 2019.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2020
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2020, Northern Trust adopted Accounting Standards Update (ASU) No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (ASU 2016-13). ASU 2016-13 significantly changed the way impairment of financial instruments is recognized by requiring immediate recognition of estimated credit losses expected to occur over the remaining life of financial instruments. The main provisions of ASU 2016-13 include (1) replacing the “incurred loss” approach under current GAAP with an “expected loss” model for instruments measured at amortized cost, (2) requiring entities to record an allowance for available for sale debt securities rather than reduce the carrying amount of the investments, as is required by the other-than-temporary-impairment model under legacy GAAP, and (3) a simplified accounting model for purchased credit-impaired debt securities and loans. Upon adoption of ASU 2016-13 On January 1, 2020, Northern Trust adopted ASU No. 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment” (ASU 2017-04). ASU 2017-04 amends the subsequent measurement of goodwill whereby Step 2 from the goodwill impairment test is eliminated. As a result, the goodwill impairment test is performed by comparing the fair value of a reporting unit to its carrying value and an impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value, not to exceed the total amount of goodwill allocated to that reporting unit. Upon adoption of ASU 2017-04, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On January 1, 2020, Northern Trust adopted ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement” (ASU 2018-13). The primary objective of ASU 2018-13 is to improve the effectiveness of disclosures in the notes to financial statements. Upon adoption of ASU 2018-13, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On January 1, 2020, Northern Trust adopted ASU No. 2018-15, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force)” (ASU 2018-15). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). Upon adoption of ASU 2018-15, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On January 1, 2020, Northern Trust adopted ASU No. 2018-17, “Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities” (ASU 2018-17). ASU 2018-17 requires that indirect interests held through related parties in common control arrangements should be considered on a proportional basis (rather than as the equivalent of a direct interest in its entirety) for determining whether fees paid to decision makers and service providers are variable interests. Upon adoption of ASU 2018-17, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On April 1, 2020, Northern Trust adopted ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (ASU 2020-04). The global transition toward alternative reference rates and away from referencing the London Interbank Offered Rate (LIBOR) and other interbank offered rates (Reference Rate Reform) is expected to have a significant impact on the volume of contract modifications, hedge accounting, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of Reference Rate Reform. ASU 2020-04 provides temporary optional expedients and exceptions for applying GAAP to contract modifications, hedging relationships, and other transactions affected by Reference Rate Reform if certain criteria are met. The main provisions of ASU 2020-04 provide the following optional expedients: (1) simplification of the accounting evaluations under current GAAP for contract modifications, including loan, debt, lease and other contracts with potential embedded derivatives, if qualifying criteria are met (2) preservation of hedging relationships without dedesignation upon certain changes to the critical terms of an existing hedging relationship due to Reference Rate Reform and other optional hedge accounting relief provisions and (3) a one-time election to sell or transfer, or both sell and transfer, debt securities classified as held to maturity that reference a rate affected by Reference Rate Reform and are classified as held to maturity before January 1, 2020. The optional expedients in ASU 2020-04 for contract modifications and hedging relationships are applied prospectively, while the one-time election to sell or transfer, or both sell and transfer debt securities classified as held to maturity may be made at any time after March 12, 2020. The optional expedients and exceptions provided by ASU 2020-04 do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, except for hedging relationships existing as of December 31, 2022 for which an entity has elected certain optional expedients and which are retained through the end of the hedging relationship.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair Value Hierarchy. The following describes the hierarchy of valuation inputs (Levels 1, 2, and 3) used to measure fair value and the primary valuation methodologies used by Northern Trust for financial instruments measured at fair value on a recurring basis. Observable inputs reflect market data obtained from sources independent of the reporting entity; unobservable inputs reflect the entity’s own assumptions about how market participants would value an asset or liability based on the best information available. GAAP requires an entity measuring fair value to maximize the use of observable inputs and minimize the use of unobservable inputs and establishes a fair value hierarchy of inputs. Financial instruments are categorized within the hierarchy based on the lowest level input that is significant to their valuation. No transfers into or out of Level 3 occurred during the nine months ended September 30, 2020 or the twelve months ended December 31, 2019. Level 1 — Quoted, active market prices for identical assets or liabilities. Northern Trust’s Level 1 assets are comprised of available for sale investments in U.S. Treasury securities. Level 2 — Observable inputs other than Level 1 prices, such as quoted active market prices for similar assets or liabilities, quoted prices for identical or similar assets in inactive markets, and model-derived valuations in which all significant inputs are observable in active markets. Northern Trust’s Level 2 assets include available for sale and trading account debt securities, the fair values of which are determined predominantly by external pricing vendors. Prices received from vendors are compared to other vendor and third-party prices. If a security price obtained from a pricing vendor is determined to exceed pre-determined tolerance levels that are assigned based on an asset type’s characteristics, the exception is researched and, if the price is not able to be validated, an alternate pricing vendor is utilized, consistent with Northern Trust’s pricing source hierarchy. As of September 30, 2020, Northern Trust’s available for sale debt securities portfolio included 2,086 Level 2 debt securities with an aggregate market value of $38.4 billion. All 2,086 debt securities were valued by external pricing vendors. As of December 31, 2019, Northern Trust’s available for sale debt securities portfolio included 1,704 Level 2 debt securities with an aggregate market value of $34.3 billion. All 1,704 debt securities were valued by external pricing vendors. Trading account debt securities, which totaled $0.6 million and $0.3 million as of September 30, 2020 and December 31, 2019, respectively, were all valued using external pricing vendors. Level 2 assets and liabilities also include derivative contracts which are valued internally using widely accepted income-based models that incorporate inputs readily observable in actively quoted markets and reflect the contractual terms of the contracts. Observable inputs include foreign exchange rates and interest rates for foreign exchange contracts; credit spreads, default probabilities, and recovery rates for credit default swap contracts; interest rates for interest rate swap contracts and forward contracts; and interest rates and volatility inputs for interest rate option contracts. Northern Trust evaluates the impact of counterparty credit risk and its own credit risk on the valuation of its derivative instruments. Factors considered include the likelihood of default by Northern Trust and its counterparties, the remaining maturities of the instruments, net exposures after giving effect to master netting arrangements or similar agreements, available collateral, and other credit enhancements in determining the appropriate fair value of derivative instruments. The resulting valuation adjustments have not been considered material. Level 3 — Valuation techniques in which one or more significant inputs are unobservable in the marketplace. Northern Trust’s Level 3 liabilities consist of swaps that Northern Trust entered into with the purchaser of 1.1 million and 1.0 million shares of Visa Inc. Class B common stock (Visa Class B common shares) previously held by Northern Trust and sold in June 2016 and 2015, respectively. Pursuant to the swaps, Northern Trust retains the risks associated with the ultimate conversion of the Visa Class B common shares into shares of Visa Inc. Class A common stock (Visa Class A common shares), such that the counterparty will be compensated for any dilutive adjustments to the conversion ratio and Northern Trust will be compensated for any anti-dilutive adjustments to the ratio. The swaps also require periodic payments from Northern Trust to the counterparty calculated by reference to the market price of Visa Class A common shares and a fixed rate of interest. The fair value of the swaps is determined using a discounted cash flow methodology. The significant unobservable inputs used in the fair value measurement are Northern Trust’s own assumptions about estimated changes in the conversion rate of the Visa Class B common shares into Visa Class A common shares, the date on which such conversion is expected to occur and the estimated growth rate of the Visa Class A common share price. See “Visa Class B Common Shares” under Note 19 — Commitments and Contingent Liabilities for further information. Northern Trust believes its valuation methods for its assets and liabilities carried at fair value are appropriate; however, the use of different methodologies or assumptions, particularly as applied to Level 3 assets and liabilities, could have a material effect on the computation of their estimated fair values. The following table presents the fair values of Northern Trust’s Level 3 liabilities as of September 30, 2020 and December 31, 2019, as well as the valuation techniques, significant unobservable inputs, and quantitative information used to develop significant unobservable inputs for such liabilities as of such dates. TABLE 36: LEVEL 3 SIGNIFICANT UNOBSERVABLE INPUTS SEPTEMBER 30, 2020 FINANCIAL INSTRUMENT FAIR VALUE VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES (1) Swaps Related to Sale of Certain Visa Class B Common Shares $32.3 million Discounted Cash Flow Conversion Rate 1.62x 1.62x Visa Class A Appreciation 8.70% 8.70% Expected Duration 12 - 33 months 20 months (1) Weighted average of expected duration based on scenario probability. DECEMBER 31, 2019 FINANCIAL INSTRUMENT FAIR VALUE VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES (1) Swaps Related to Sale of Certain Visa Class B Common Shares $33.4 million Discounted Cash Flow Conversion Rate 1.62x 1.62x Visa Class A Appreciation 8.54% 8.54% Expected Duration 12 - 36 months 22 months (1) Weighted average of expected duration based on scenario probability. The following table presents assets and liabilities measured at fair value on a recurring basis as of September 30, 2020 and December 31, 2019, segregated by fair value hierarchy level. TABLE 37: RECURRING BASIS HIERARCHY LEVELING SEPTEMBER 30, 2020 (In Millions) LEVEL 1 LEVEL 2 LEVEL 3 NETTING ASSETS/LIABILITIES AT FAIR VALUE Debt Securities Available for Sale U.S. Government $ 4,165.2 $ — $ — $ — $ 4,165.2 Obligations of States and Political Subdivisions — 2,600.5 — — 2,600.5 Government Sponsored Agency — 24,568.8 — — 24,568.8 Non-U.S. Government — 937.6 — — 937.6 Corporate Debt — 2,627.4 — — 2,627.4 Covered Bonds — 516.8 — — 516.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds — 2,552.8 — — 2,552.8 Other Asset-Backed — 3,559.4 — — 3,559.4 Commercial Mortgage-Backed — 1,015.2 — — 1,015.2 Other — 7.3 — — 7.3 Total Available for Sale 4,165.2 38,385.8 — — 42,551.0 Trading Account 0.3 0.3 — — 0.6 Total Available for Sale and Trading Debt Securities 4,165.5 38,386.1 — — 42,551.6 Other Assets Derivative Assets Foreign Exchange Contracts — 2,279.5 — (1,405.7) 873.8 Interest Rate Contracts — 333.7 — (2.6) 331.1 Total Derivative Assets — 2,613.2 — (1,408.3) 1,204.9 Other Liabilities Derivative Liabilities Foreign Exchange Contracts — 2,326.3 — (1,493.6) 832.7 Interest Rate Contracts — 142.2 — (109.7) 32.5 Other Financial Derivatives (1) — — 32.3 — 32.3 Total Derivative Liabilities $ — $ 2,468.5 $ 32.3 $ (1,603.3) $ 897.5 Note: Northern Trust has elected to net derivative assets and liabilities when legally enforceable master netting arrangements or similar agreements exist between Northern Trust and the counterparty. As of September 30, 2020, derivative assets and liabilities shown above also include reductions of $212.7 million and $407.7 million, respectively, as a result of cash collateral received from and deposited with derivative counterparties. (1) This line consists of swaps related to the sale of certain Visa Class B common shares. DECEMBER 31, 2019 (In Millions) LEVEL 1 LEVEL 2 LEVEL 3 NETTING ASSETS/LIABILITIES AT FAIR VALUE Debt Securities Available for Sale U.S. Government $ 4,549.1 $ — $ — $ — $ 4,549.1 Obligations of States and Political Subdivisions — 1,615.3 — — 1,615.3 Government Sponsored Agency — 23,271.2 — — 23,271.2 Non-U.S. Government — 3.3 — — 3.3 Corporate Debt — 2,402.7 — — 2,402.7 Covered Bonds — 769.9 — — 769.9 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds — 2,127.6 — — 2,127.6 Other Asset-Backed — 3,330.5 — — 3,330.5 Commercial Mortgage-Backed — 797.7 — — 797.7 Other — 9.0 — — 9.0 Total Available for Sale 4,549.1 34,327.2 — — 38,876.3 Trading Account — 0.3 — — 0.3 Total Available for Sale and Trading Debt Securities 4,549.1 34,327.5 — — 38,876.6 Other Assets Derivative Assets Foreign Exchange Contracts — 3,234.8 — (2,334.1) 900.7 Interest Rate Contracts — 152.9 — (3.9) 149.0 Total Derivative Assets — 3,387.7 — (2,338.0) 1,049.7 Other Liabilities Derivative Liabilities Foreign Exchange Contracts — 3,182.2 — (1,548.6) 1,633.6 Interest Rate Contracts — 97.4 — (57.3) 40.1 Other Financial Derivatives (1) — — 33.4 (12.5) 20.9 Total Derivative Liabilities $ — $ 3,279.6 $ 33.4 $ (1,618.4) $ 1,694.6 Note: Northern Trust has elected to net derivative assets and liabilities when legally enforceable master netting arrangements or similar agreements exist between Northern Trust and the counterparty. As of December 31, 2019, derivative assets and liabilities shown above also include reductions of $1,136.8 million and $417.2 million, respectively, as a result of cash collateral received from and deposited with derivative counterparties. (1) This line consists of swaps related to the sale of certain Visa Class B common shares. The following table presents the changes in Level 3 liabilities for the three and nine months ended September 30, 2020 and 2019. TABLE 38: CHANGES IN LEVEL 3 LIABILITIES (In Millions) SWAPS RELATED TO SALE OF CERTAIN VISA CLASS B COMMON SHARES THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 Fair Value at July 1 $ 31.3 $ 34.7 Total (Gains) Losses: Included in Earnings (1) 5.3 6.7 Purchases, Issues, Sales, and Settlements Settlements (4.3) (3.7) Fair Value at September 30 $ 32.3 $ 37.7 (1) (Gains) losses are recorded in Other Operating Income on the consolidated statements of income. NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 Fair Value at January 1 $ 33.4 $ 32.8 Total (Gains) Losses: Included in Earnings (1) 11.0 14.9 Purchases, Issues, Sales, and Settlements Settlements (12.1) (10.0) Fair Value at September 30 $ 32.3 $ 37.7 (1) (Gains) losses are recorded in Other Operating Income on the consolidated statements of income. Carrying values of assets and liabilities that are not measured at fair value on a recurring basis may be adjusted to fair value in periods subsequent to their initial recognition, for example, to record an impairment of an asset. GAAP requires entities to separately disclose these subsequent fair value measurements and to classify them under the fair value hierarchy. Assets measured at fair value on a nonrecurring basis at September 30, 2020 and December 31, 2019, all of which were categorized as Level 3 under the fair value hierarchy, were comprised of nonaccrual loans whose values were based on real estate and other available collateral, and of other real estate owned (OREO) properties. Fair values of real estate loan collateral were estimated using a market approach typically supported by third-party valuations and property-specific fees and taxes. The fair values of real estate loan collateral were subject to adjustments to reflect management’s judgment as to realizable value and consisted of discount factors ranging from 15.0% to 20.0% with a weighted average based on fair values of 15.2% and 15.3% as of September 30, 2020 and December 31, 2019, respectively. Other loan collateral, which typically consists of accounts receivable, inventory and equipment, is valued using a market approach adjusted for asset-specific characteristics and in limited instances third-party valuations are used. OREO assets are carried at the lower of cost or fair value less estimated costs to sell, with fair value typically based on third-party appraisals. Collateral-based nonaccrual loans that have been adjusted to fair value totaled $21.2 million and $8.0 million at September 30, 2020 and December 31, 2019, respectively. The following table presents the fair values of Northern Trust’s Level 3 assets that were measured at fair value on a nonrecurring basis as of September 30, 2020 and December 31, 2019, as well as the valuation technique, significant unobservable inputs and quantitative information used to develop the significant unobservable inputs for such assets as of such dates. TABLE 39: LEVEL 3 NONRECURRING BASIS SIGNIFICANT UNOBSERVABLE INPUTS SEPTEMBER 30, 2020 FINANCIAL INSTRUMENT FAIR VALUE (1) VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES Loans $21.2 million Market Approach Discount factor applied to real estate collateral-based loans to reflect realizable value 15.0% - 20.0% 15.2% (1) Includes real estate collateral-based loans and other collateral-based loans. DECEMBER 31, 2019 FINANCIAL INSTRUMENT FAIR VALUE (1) VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES Loans $8.0 million Market Approach Discount factor applied to real estate collateral-based loans to reflect realizable value 15.0 % - 20.0% 15.3% (1) Includes real estate collateral-based loans and other collateral-based loans. The following table summarizes the fair values of all financial instruments. TABLE 40: FAIR VALUE OF FINANCIAL INSTRUMENTS SEPTEMBER 30, 2020 FAIR VALUE (In Millions) BOOK VALUE TOTAL FAIR VALUE LEVEL 1 LEVEL 2 LEVEL 3 ASSETS Cash and Due from Banks $ 4,737.5 $ 4,737.5 $ 4,737.5 $ — $ — Federal Reserve and Other Central Bank Deposits 39,244.6 39,244.6 — 39,244.6 — Interest-Bearing Deposits with Banks 2,754.4 2,754.4 — 2,754.4 — Federal Funds Sold and Securities Purchased under Agreements to Resell 1,533.4 1,533.4 — 1,533.4 — Debt Securities Available for Sale (1) 42,551.0 42,551.0 4,165.2 38,385.8 — Held to Maturity 16,754.0 16,746.5 99.0 16,647.5 — Trading Account 0.6 0.6 0.3 0.3 — Loans (excluding Leases) Held for Investment 32,521.2 33,001.4 — — 33,001.4 Client Security Settlement Receivables 2,296.8 2,296.8 — 2,296.8 — Other Assets Federal Reserve and Federal Home Loan Bank Stock 239.7 239.7 — 239.7 — Community Development Investments 761.3 761.3 — 761.3 — Employee Benefit and Deferred Compensation 214.6 230.0 143.6 86.4 — LIABILITIES Deposits Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing $ 59,756.8 $ 59,756.8 $ 59,756.8 $ — $ — Savings Certificates and Other Time 1,486.7 1,496.5 — 1,496.5 — Non U.S. Offices Interest-Bearing 61,345.6 61,345.6 — 61,345.6 — Federal Funds Purchased 2,203.7 2,203.7 — 2,203.7 — Securities Sold Under Agreements to Repurchase 269.8 269.8 — 269.8 — Other Borrowings 5,771.7 5,772.9 — 5,772.9 — Senior Notes 3,655.6 3,731.0 — 3,731.0 — Long-Term Debt Subordinated Debt 1,196.0 1,250.0 — 1,250.0 — Floating Rate Capital Debt 277.7 255.6 — 255.6 — Other Liabilities Standby Letters of Credit 23.9 23.9 — — 23.9 Loan Commitments 55.7 55.7 — — 55.7 Derivative Instruments Asset/Liability Management Foreign Exchange Contracts Assets $ 36.8 $ 36.8 $ — $ 36.8 $ — Liabilities 112.8 112.8 — 112.8 — Interest Rate Contracts Assets 10.5 10.5 — 10.5 — Liabilities 18.9 18.9 — 18.9 — Other Financial Derivatives Liabilities (2) 32.3 32.3 — — 32.3 Client-Related and Trading Foreign Exchange Contracts Assets 2,242.7 2,242.7 — 2,242.7 — Liabilities 2,213.5 2,213.5 — 2,213.5 — Interest Rate Contracts Assets 323.2 323.2 — 323.2 — Liabilities 123.3 123.3 — 123.3 — (1) Refer to the table located on page 46 for the disaggregation of available for sale debt securities. (2) This line consists of swaps related to the sale of certain Visa Class B common shares. DECEMBER 31, 2019 FAIR VALUE (In Millions) BOOK VALUE TOTAL FAIR VALUE LEVEL 1 LEVEL 2 LEVEL 3 ASSETS Cash and Due from Banks $ 4,459.2 $ 4,459.2 $ 4,459.2 $ — $ — Federal Reserve and Other Central Bank Deposits 33,886.0 33,886.0 — 33,886.0 — Interest-Bearing Deposits with Banks 4,877.1 4,877.1 — 4,877.1 — Federal Funds Sold and Securities Purchased under Agreements to Resell 712.8 712.8 — 712.8 — Debt Securities Available for Sale (1) 38,876.3 38,876.3 4,549.1 34,327.2 — Held to Maturity 12,284.5 12,249.3 138.8 12,110.5 — Trading Account 0.3 0.3 — 0.3 — Loans (excluding Leases) Held for Investment 31,239.5 31,517.8 — — 31,517.8 Client Security Settlement Receivables 845.7 845.7 — 845.7 — Other Assets Federal Reserve and Federal Home Loan Bank Stock 301.2 301.2 — 301.2 — Community Development Investments 749.3 749.3 — 749.3 — Employee Benefit and Deferred Compensation 199.5 207.6 131.0 76.6 — LIABILITIES Deposits Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing $ 47,733.6 $ 47,733.6 $ 47,733.6 $ — $ — Savings Certificates and Other Time 986.7 994.2 — 994.2 — Non U.S. Offices Interest-Bearing 60,400.3 60,400.3 — 60,400.3 — Federal Funds Purchased 552.9 552.9 — 552.9 — Securities Sold Under Agreements to Repurchase 489.7 489.7 — 489.7 — Other Borrowings 6,744.8 6,745.9 — 6,745.9 — Senior Notes 2,573.0 2,593.0 — 2,593.0 — Long-Term Debt Subordinated Debt 1,148.1 1,169.5 — 1,169.5 — Floating Rate Capital Debt 277.7 262.1 — 262.1 — Other Liabilities Standby Letters of Credit 25.5 25.5 — — 25.5 Loan Commitments 32.3 32.3 — — 32.3 Derivative Instruments Asset/Liability Management Foreign Exchange Contracts Assets $ 83.1 $ 83.1 $ — $ 83.1 $ — Liabilities 24.1 24.1 — 24.1 — Interest Rate Contracts Assets 20.5 20.5 — 20.5 — Liabilities 21.1 21.1 — 21.1 — Other Financial Derivatives Liabilities (2) 33.4 33.4 — — 33.4 Client-Related and Trading Foreign Exchange Contracts Assets 3,151.7 3,151.7 — 3,151.7 — Liabilities 3,158.1 3,158.1 — 3,158.1 — Interest Rate Contracts Assets 132.4 132.4 — 132.4 — Liabilities 76.3 76.3 — 76.3 — (1) Refer to the table located on page 47 for the disaggregation of available for sale debt securities. (2) This line consists of swaps related to the sale of certain Visa Class B common shares.

Securities

Securities	9 Months Ended
	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Securities	Securities Debt Securities Available for Sale. The following tables provide the amortized cost and fair values at September 30, 2020 and December 31, 2019, and remaining maturities of debt securities available for sale at September 30, 2020. TABLE 41: RECONCILIATION OF AMORTIZED COST TO FAIR VALUE OF DEBT SECURITIES AVAILABLE FOR SALE SEPTEMBER 30, 2020 (In Millions) AMORTIZED COST GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR VALUE U.S. Government $ 4,083.9 $ 81.3 $ — $ 4,165.2 Obligations of States and Political Subdivisions 2,465.2 136.3 1.0 2,600.5 Government Sponsored Agency 24,162.6 427.4 21.2 24,568.8 Non-U.S. Government 936.8 0.9 0.1 937.6 Corporate Debt 2,548.7 80.9 2.2 2,627.4 Covered Bonds 508.5 8.3 — 516.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 2,486.4 66.7 0.3 2,552.8 Other Asset-Backed 3,522.3 46.6 9.5 3,559.4 Commercial Mortgage-Backed 937.5 78.4 0.7 1,015.2 Other 7.3 — — 7.3 Total $ 41,659.2 $ 926.8 $ 35.0 $ 42,551.0 DECEMBER 31, 2019 (In Millions) AMORTIZED COST GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR VALUE U.S. Government $ 4,527.5 $ 26.7 $ 5.1 $ 4,549.1 Obligations of States and Political Subdivisions 1,604.0 24.6 13.3 1,615.3 Government Sponsored Agency 23,247.5 101.8 78.1 23,271.2 Non-U.S. Government 3.3 — — 3.3 Corporate Debt 2,378.9 27.8 4.0 2,402.7 Covered Bonds 766.3 4.4 0.8 769.9 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 2,091.3 37.4 1.1 2,127.6 Other Asset-Backed 3,324.5 11.3 5.3 3,330.5 Commercial Mortgage-Backed 769.9 28.7 0.9 797.7 Other 9.0 — — 9.0 Total $ 38,722.2 $ 262.7 $ 108.6 $ 38,876.3 TABLE 42: REMAINING MATURITY OF DEBT SECURITIES AVAILABLE FOR SALE SEPTEMBER 30, 2020 ONE YEAR OR LESS ONE TO FIVE YEARS FIVE TO TEN YEARS OVER TEN YEARS TOTAL (In Millions) AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE U.S. Government $ 1,802.3 $ 1,805.4 $ 1,834.8 $ 1,876.1 $ 446.8 $ 483.7 $ — $ — $ 4,083.9 $ 4,165.2 Obligations of States and Political Subdivisions 16.4 16.4 210.9 222.8 2,187.7 2,311.0 50.2 50.3 2,465.2 2,600.5 Government Sponsored Agency 6,077.0 6,160.5 9,520.9 9,669.4 6,111.1 6,224.2 2,453.6 2,514.7 24,162.6 24,568.8 Non-U.S. Government 737.9 738.2 40.7 40.6 158.2 158.8 — — 936.8 937.6 Corporate Debt 547.1 552.9 2,001.6 2,074.5 — — — — 2,548.7 2,627.4 Covered Bonds 24.4 24.5 484.1 492.3 — — — — 508.5 516.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 334.9 335.1 2,046.0 2,111.8 105.5 105.9 — — 2,486.4 2,552.8 Other Asset-Backed 412.4 419.0 2,658.0 2,690.0 356.0 354.5 95.9 95.9 3,522.3 3,559.4 Commercial Mortgage-Backed 16.6 16.7 336.2 360.3 567.1 620.6 17.6 17.6 937.5 1,015.2 Other 7.3 7.3 — — — — — — 7.3 7.3 Total $ 9,976.3 $ 10,076.0 $ 19,133.2 $ 19,537.8 $ 9,932.4 $ 10,258.7 $ 2,617.3 $ 2,678.5 $ 41,659.2 $ 42,551.0 Note: Mortgage-backed and asset-backed securities are included in the above table taking into account anticipated future prepayments. Debt Securities Available for Sale with Unrealized Losses. The following table provides information regarding debt securities available for sale with no credit losses reported that had been in a continuous unrealized loss position for less than twelve months and for twelve months or longer as of September 30, 2020 and December 31, 2019. TABLE 43: DEBT SECURITIES AVAILABLE FOR SALE IN UNREALIZED LOSS POSITION WITH NO CREDIT LOSSES REPORTED AS OF SEPTEMBER 30, 2020 LESS THAN 12 MONTHS 12 MONTHS OR LONGER TOTAL (In Millions) FAIR UNREALIZED FAIR UNREALIZED FAIR UNREALIZED Obligations of States and Political Subdivisions $ 230.4 $ 1.0 $ — $ — $ 230.4 $ 1.0 Government Sponsored Agency 2,578.6 6.8 2,862.3 14.4 5,440.9 21.2 Non-U.S. Government 26.5 0.1 — — 26.5 0.1 Corporate Debt 69.1 1.0 76.1 1.2 145.2 2.2 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 146.3 0.2 158.7 0.1 305.0 0.3 Other Asset-Backed 631.2 1.0 846.3 8.5 1,477.5 9.5 Commercial Mortgage-Backed 76.3 0.7 — — 76.3 0.7 Total $ 3,758.4 $ 10.8 $ 3,943.4 $ 24.2 $ 7,701.8 $ 35.0 AS OF DECEMBER 31, 2019 LESS THAN 12 MONTHS 12 MONTHS OR LONGER TOTAL (In Millions) FAIR UNREALIZED FAIR UNREALIZED FAIR UNREALIZED U.S. Government $ 252.2 $ 2.8 $ 899.7 $ 2.3 $ 1,151.9 $ 5.1 Obligations of States and Political Subdivisions 902.4 13.3 — — 902.4 13.3 Government Sponsored Agency 5,405.0 35.6 7,818.4 42.5 13,223.4 78.1 Corporate Debt 279.3 1.1 492.7 2.9 772.0 4.0 Covered Bonds 138.7 0.7 25.0 0.1 163.7 0.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 217.5 1.0 155.2 0.1 372.7 1.1 Other Asset-Backed 592.4 1.8 1,164.9 3.5 1,757.3 5.3 Commercial Mortgage-Backed 62.8 0.7 59.3 0.2 122.1 0.9 Total $ 7,850.3 $ 57.0 $ 10,615.2 $ 51.6 $ 18,465.5 $ 108.6 As of September 30, 2020, 475 debt securities available for sale with a combined fair value of $7.7 billion were in an unrealized loss position, with their unrealized losses totaling $35.0 million. Unrealized losses related to debt securities available for sale of $21.2 million and $9.5 million related to government-sponsored agency and other asset-backed securities, respectively, are primarily attributable to changes in market interest rates and credit spreads since their purchase. Unrealized losses related to corporate debt securities with no credit losses reported of $2.2 million are primarily attributable to changes in market interest rates as well as credit spreads since their purchase. As of September 30, 2020, 21% of the corporate debt securities available for sale portfolio were backed by guarantees provided by U.S. and non-U.S. governmental entities. The remaining unrealized losses on Northern Trust’s debt securities available for sale portfolio as of September 30, 2020, are attributable to changes in overall market interest rates or credit spreads. As of September 30, 2020, Northern Trust did not intend to sell any debt securities available for sale in an unrealized loss position and it was more likely than not that Northern Trust would not be required to sell any such investment before the recovery of its amortized cost basis, which may be maturity. Debt securities available for sale impairment reviews are conducted quarterly to identify and evaluate securities that have indications of possible credit losses. A determination as to whether a security’s decline in market value is related to credit impairment takes into consideration numerous factors and the relative significance of any single factor can vary by security. Factors Northern Trust considers in determining whether impairment is credit related include, but are not limited to, the severity of the impairment; the cause of the impairment and the financial condition and near-term prospects of the issuer; activity in the market of the issuer, which may indicate adverse credit conditions; Northern Trust’s intent regarding the sale of the security as of the balance sheet date; and the likelihood that Northern Trust will not be required to sell the security for a period of time sufficient to allow for the recovery of the security’s amortized cost basis. For each security meeting the requirements of Northern Trust’s internal screening process, an extensive review is conducted to determine if a credit loss has occurred. There was no provision for corporate debt securities available for sale for the three and nine months ended September 30, 2020 and no allowance for credit losses for corporate debt securities available for sale as of September 30, 2020. The process for identifying credit losses for corporate debt available for sale securities is based on the best estimate of cash flows to be collected from the security, discounted using the security’s effective interest rate. If the present value of the expected cash flows is found to be less than the current amortized cost of the security, an allowance for credit losses is generally recorded equal to the difference between the two amounts, limited to the amount the amortized cost basis exceeds the fair value of the security. For additional information, please refer to Note 7 — Allowance for Credit Losses. For a description of Northern Trust’s accounting policies applied prior to the adoption of ASU 2016-13, refer to Note 1 — Summary of Significant Accounting Policies and Note 4 — Securities included under Item 8. Financial Statements and Supplementary Data in the Annual Report on Form 10-K for the year ended December 31, 2019. Debt Securities Held to Maturity. The following tables provide the amortized cost and fair values at September 30, 2020 and December 31, 2019, and remaining maturities of debt securities held to maturity at September 30, 2020. TABLE 44: RECONCILIATION OF AMORTIZED COST TO FAIR VALUE OF DEBT SECURITIES HELD TO MATURITY SEPTEMBER 30, 2020 (In Millions) AMORTIZED GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR U.S Government $ 99.0 $ — $ — $ 99.0 Obligations of States and Political Subdivisions 2.6 0.1 — 2.7 Government Sponsored Agency 3.4 0.3 — 3.7 Non-U.S. Government 7,551.8 8.1 0.2 7,559.7 Corporate Debt 530.3 5.5 — 535.8 Covered Bonds 3,361.7 25.4 1.0 3,386.1 Certificates of Deposit 726.3 — — 726.3 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 3,390.5 42.8 0.3 3,433.0 Other Asset-Backed 645.8 0.7 0.2 646.3 Other 442.6 — 88.7 353.9 Total $ 16,754.0 $ 82.9 $ 90.4 $ 16,746.5 DECEMBER 31, 2019 (In Millions) AMORTIZED GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR U.S. Government $ 138.8 $ — $ — $ 138.8 Obligations of States and Political Subdivisions 10.1 0.2 — 10.3 Government Sponsored Agency 4.1 0.2 — 4.3 Non-U.S. Government 4,076.0 5.3 2.5 4,078.8 Corporate Debt 405.1 1.4 0.3 406.2 Covered Bonds 3,006.7 16.1 2.4 3,020.4 Certificates of Deposit 262.9 — — 262.9 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 3,285.4 21.7 2.1 3,305.0 Other Asset-Backed 804.3 0.7 0.3 804.7 Other 291.1 0.1 73.3 217.9 Total $ 12,284.5 $ 45.7 $ 80.9 $ 12,249.3 As of September 30, 2020, the $16.8 billion debt securities held to maturity portfolio had an unrealized loss of $88.7 million related to other residential mortgage-backed securities, which are primarily attributable to changes in overall market interest rates and credit spreads since their purchase. TABLE 45: REMAINING MATURITY OF DEBT SECURITIES HELD TO MATURITY SEPTEMBER 30, 2020 ONE YEAR OR LESS ONE TO FIVE YEARS FIVE TO TEN YEARS OVER TEN YEARS TOTAL (In Millions) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value U.S. Government $ 99.0 $ 99.0 $ — $ — $ — $ — $ — $ — $ 99.0 $ 99.0 Obligations of States and Political Subdivisions 1.6 1.6 1.0 1.1 — — — — 2.6 2.7 Government Sponsored Agency 0.5 0.6 1.5 1.6 0.9 1.0 0.5 0.5 3.4 3.7 Non-U.S. Government 7,291.5 7,293.2 260.3 266.5 — — — — 7,551.8 7,559.7 Corporate Debt 125.0 125.2 405.3 410.6 — — — — 530.3 535.8 Covered Bonds 1,228.1 1,233.1 2,133.6 2,153.0 — — — — 3,361.7 3,386.1 Certificates of Deposit 726.3 726.3 — — — — — — 726.3 726.3 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 832.7 837.1 2,325.2 2,362.7 232.6 233.2 — — 3,390.5 3,433.0 Other Asset-Backed 190.1 190.1 435.4 435.8 20.3 20.4 — — 645.8 646.3 Other 21.3 20.8 251.4 228.1 58.9 49.4 111.0 55.6 442.6 353.9 Total $ 10,516.1 $ 10,527.0 $ 5,813.7 $ 5,859.4 $ 312.7 $ 304.0 $ 111.5 $ 56.1 $ 16,754.0 $ 16,746.5 Note: Mortgage-backed and asset-backed securities are included in the above table taking into account anticipated future prepayments. Debt securities held to maturity consist of securities that management intends to, and Northern Trust has the ability to, hold until maturity. During the three months ended September 30, 2020, no securities were transferred from available for sale to held to maturity. During the nine months ended September 30, 2020, $301.5 million securities reflected in U.S. government were transferred from available for sale to held to maturity, all of which were transferred in the second quarter of 2020. During the three and nine months ended September 30, 2019, $160.8 million securities reflected in covered bonds were transferred from available for sale to held to maturity. Credit Quality Indicators. The following table provides the amortized cost of debt securities held to maturity by credit rating. TABLE 46: AMORTIZED COST OF DEBT SECURITIES HELD TO MATURITY BY CREDIT RATING AS OF SEPTEMBER 30, 2020 (In Millions) AAA AA A BBB NOT RATED TOTAL U.S. Government $ 99.0 $ — $ — $ — $ — $ 99.0 Obligations of States and Political Subdivisions — 0.6 0.7 1.3 — 2.6 Government Sponsored Agency 3.4 — — — — 3.4 Non-U.S. Government 335.6 1,269.7 5,899.8 46.7 — 7,551.8 Corporate Debt 3.6 254.7 272.0 — — 530.3 Covered Bonds 3,361.7 — — — — 3,361.7 Certificates of Deposit — — — — 726.3 726.3 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 2,423.6 966.9 — — — 3,390.5 Other Asset-Backed 645.8 — — — — 645.8 Other — — — — 442.6 442.6 Total $ 6,872.7 $ 2,491.9 $ 6,172.5 $ 48.0 $ 1,168.9 $ 16,754.0 Credit quality indicators are metrics that provide information regarding the relative credit risk of debt securities. Northern Trust maintains a high quality debt securities portfolio, with 41% of the held to maturity portfolio at September 30, 2020, composed of U.S. Treasury and government sponsored agency securities and other triple-A rated securities. The remaining held to maturity debt securities portfolio was comprised of 15% rated double-A, 37% rated below double-A, and 7% not rated by Moody’s Investors Service, Standard and Poor’s or Fitch Ratings. Securities not explicitly rated were grouped where possible under the credit rating of the issuer of the security. Investment Security Gains and Losses. There were no sales of debt securities during the three months ended September 30, 2020. Proceeds of $689.2 million from the sale of debt securities during the nine months ended September 30, 2020 and $177.3 million and $406.6 million from the sale of debt securities during the three- and nine- months ended September 30, 2019, respectively, resulted in the following gains and losses shown below. TABLE 47: INVESTMENT SECURITY GAINS AND LOSSES THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Gross Realized Debt Securities Gains $ — $ 0.1 $ 3.4 $ 1.6 Gross Realized Debt Securities Losses — (0.4) (3.3) (2.2) Changes in Other-Than-Temporary Impairment Losses (1) — (0.1) — (0.3) Net Investment Security (Losses) Gains $ — $ (0.4) $ 0.1 $ (0.9)

Securities Sold Under Agreement

Securities Sold Under Agreements to Repurchase	9 Months Ended
	Sep. 30, 2020
Banking and Thrift, Other Disclosures [Abstract]
Securities Sold Under Agreements to Repurchase	Securities Sold Under Agreements to Repurchase Securities sold under agreements to repurchase are accounted for as collateralized financings and recorded at the amounts at which the securities were sold plus accrued interest. To minimize any potential credit risk associated with these transactions, the fair value of the securities sold is monitored, limits are set on exposure with counterparties, and the financial condition of counterparties is regularly assessed. Securities sold under agreements to repurchase are held by the counterparty until the repurchase. The following table provides information regarding repurchase agreements that are accounted for as secured borrowings as of September 30, 2020 and December 31, 2019. TABLE 48: REPURCHASE AGREEMENTS ACCOUNTED FOR AS SECURED BORROWINGS REMAINING CONTRACTUAL MATURITY OF THE AGREEMENTS OVERNIGHT AND CONTINUOUS ($ In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 U.S. Treasury and Agency Securities $ 269.8 $ 489.7 Total Borrowings 269.8 489.7 Gross Amount of Recognized Liabilities for Repurchase Agreements in Note 21 269.8 489.7 Amounts related to agreements not included in Note 21 — —

Loans and Leases

Loans and Leases	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Loans and Leases	Loans and Leases Amounts outstanding for loans and leases, by segment and class, are shown in the following table. During the first quarter of 2020, the Corporation implemented a change in the classification of certain loans and leases to specific segments to enhance the consistency of its reporting across various regulatory regimes. As a result, the loan and lease balances as of December 31, 2019 below have been adjusted to conform to the presentation for periods ended after such date. The adjustments generally reflect reclassification of loans from the commercial real estate class to commercial and institutional, residential real estate, and private client classes. There was no impact on total loans and leases previously reported. TABLE 49: LOANS AND LEASES (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Commercial Commercial and Institutional $ 9,524.0 $ 9,091.1 Commercial Real Estate 3,373.6 3,104.3 Non-U.S. 1,441.0 1,576.3 Lease Financing, net 30.1 65.6 Other 213.0 164.0 Total Commercial 14,581.7 14,001.3 Personal Private Client 11,893.0 11,071.4 Residential Real Estate 5,928.3 6,095.0 Non-U.S. 338.7 174.8 Other 24.6 67.1 Total Personal 18,184.6 17,408.3 Total Loans and Leases $ 32,766.3 $ 31,409.6 Residential real estate loans consist of traditional first lien mortgages and equity credit lines that generally require a loan-to-collateral value of no more than 65% to 80% at inception. Northern Trust’s equity credit line products generally have draw periods of up to 10 years and a balloon payment of any outstanding balance is due at maturity. Payments are interest-only with variable interest rates. Northern Trust does not offer equity credit lines that include an option to convert the outstanding balance to an amortizing payment loan. As of September 30, 2020 and December 31, 2019, equity credit lines totaled $351.8 million and $448.5 million, respectively, and equity credit lines for which first liens were held by Northern Trust represented 97% of the total equity credit lines as of both September 30, 2020 and December 31, 2019. Included within the non-U.S., commercial-other and personal-other classes are short-duration advances primarily related to the processing of custodied client investments, totaling $1.3 billion at September 30, 2020 and $1.1 billion at December 31, 2019, respectively. Demand deposit overdrafts reclassified as loan balances totaled $11.6 million and $90.4 million at September 30, 2020 and December 31, 2019, respectively. As of September 30, 2020 and December 31, 2019, there were $18.6 million and $53.6 million of leases, respectively, classified as held for sale related to the decision to sell substantially all of the lease portfolio. As of September 30, 2020 and December 31, 2019, there were no loans classified as held for sale. Paycheck Protection Program. In response to the COVID-19 pandemic, Northern Trust became a lender under the Paycheck Protection Program (PPP), which was created by the Coronavirus Aid, Relief, and Economic Security (CARES) Act and is administered by the U.S. Small Business Administration (SBA). Loans issued under the PPP are funded by Northern Trust directly to participating borrowers. The PPP loans are guaranteed by the SBA and borrowers are eligible to apply for PPP loan forgiveness for up to the full principal amount and accrued interest of the PPP loan. To the extent that the borrower has used the PPP loan proceeds to cover eligible costs and has met all other SBA loan forgiveness requirements, the SBA will determine loan forgiveness under the CARES Act and will pay to Northern Trust the eligible PPP loan forgiven amount, which will be credited to the borrower’s loan to repay or pay down the PPP loan. The SBA forgiveness portal opened on August 10, 2020 and Northern Trust’s vendor portal opened on September 11, 2020 to begin processing the PPP loan forgiveness applications. 109 PPP loan forgiveness applications were in process as of September 30, 2020, though no PPP loans of the total $215.3 million PPP loans had been submitted for forgiveness approval to the SBA as of such date. When Northern Trust submits the forgiveness applications to the SBA, the SBA will have at least 90 days to respond to Northern Trust as to the approval or denial of such application. As of September 30, 2020, Northern Trust had, net of repayments, $215.3 million or 1,127 loans, under the PPP in the commercial and institutional portfolio with an average loan balance of $0.2 million. As of September 30, 2020, for its origination efforts Northern Trust had received approximately $2.6 million in SBA fees, net of service charges. Northern Trust accounts for loans originated under the PPP as loan receivables in accordance with Accounting Standards Codification (ASC) 310 and recognizes such loans at the principal amount less the net amount of loan origination fees. PPP loans are reported in Total Loans and Leases on the consolidated balance sheets. The SBA provides a 100% guarantee on PPP loans covering principal and interest. Northern Trust considers the risk mitigating effects of these guarantees, and accounts for them as a credit enhancement embedded in the contract. As a result, no allowance for credit losses is measured for Northern Trust’s exposure under the PPP. Credit Quality Indicators. Credit quality indicators are statistics, measurements or other metrics that provide information regarding the relative credit risk of loans and leases. Northern Trust utilizes a variety of credit quality indicators to assess the credit risk of loans and leases at the segment, class, and individual credit exposure levels. As part of its credit process, Northern Trust utilizes an internal borrower risk rating system to support identification, approval, and monitoring of credit risk. Borrower risk ratings are used in credit underwriting and management reporting. Risk ratings are used for ranking the credit risk of borrowers and the probability of their default. Each borrower is rated using one of a number of ratings models, which consider both quantitative and qualitative factors. The ratings models vary among classes of loans and leases in order to capture the unique risk characteristics inherent within each particular type of credit exposure. Provided below are the more significant performance indicator attributes considered within Northern Trust’s borrower rating models, by loan and lease class. • Commercial and Institutional: leverage, profit margin, liquidity, asset size and capital levels; • Commercial Real Estate: debt service coverage, loan-to-value ratio, leasing status and guarantor support; • Lease Financing and Commercial-Other: leverage, profit margin, liquidity, asset size and capital levels; • Non-U.S.: leverage, profit margin, liquidity, return on assets and capital levels; • Residential Real Estate: payment history, credit bureau scores and loan-to-value ratio; • Private Client: cash-flow-to-debt and net worth ratios, leverage and liquidity; and • Personal-Other: cash-flow-to-debt and net worth ratios. While the criteria vary by model, the objective is for the borrower ratings to be consistent in both the measurement and ranking of risk. Each model is calibrated to a master rating scale to support this consistency. Ratings for borrowers not in default range from “1” for the strongest credits to “7” for the weakest non-defaulted credits. Ratings of “8” or “9” are used for defaulted borrowers. Borrower risk ratings are monitored and are revised when events or circumstances indicate a change is required. Risk ratings are generally validated at least annually. Loan and lease segment and class balances as of September 30, 2020 are provided in the following table, segregated by borrower ratings into “1 to 3,” “4 to 5” and “6 to 9” (watch list and nonaccrual status) categories by year of origination at amortized cost basis. Loans that are held for investment are reported at the principal amount outstanding, net of unearned income. TABLE 50: CREDIT QUALITY INDICATOR AT AMORTIZED COST BASIS BY ORIGINATION YEAR September 30, 2020 TERM LOANS AND LEASES REVOLVING LOANS REVOLVING LOANS CONVERTED TO TERM LOANS (In Millions) 2020 2019 2018 2017 2016 PRIOR TOTAL Commercial Commercial and Institutional Risk Rating: 1 to 3 Category $ 245.2 $ 571.6 $ 208.2 $ 142.8 $ 457.8 $ 465.2 $ 3,286.6 $ 2.0 $ 5,379.4 4 to 5 Category 614.0 579.5 379.7 428.4 143.0 180.4 1,346.4 50.1 3,721.5 6 to 9 Category 36.7 134.7 39.0 29.0 38.5 20.5 124.7 — 423.1 Total Commercial and Institutional 895.9 1,285.8 626.9 600.2 639.3 666.1 4,757.7 52.1 9,524.0 Commercial Real Estate Risk Rating: 1 to 3 Category 359.5 205.7 71.8 40.5 24.9 113.4 126.5 8.9 951.2 4 to 5 Category 453.4 758.0 294.1 110.6 178.5 383.9 72.4 13.7 2,264.6 6 to 9 Category 7.5 55.2 32.5 32.0 1.6 29.0 — — 157.8 Total Commercial Real Estate 820.4 1,018.9 398.4 183.1 205.0 526.3 198.9 22.6 3,373.6 Non-U.S. Risk Rating: 1 to 3 Category 790.8 15.9 10.0 10.7 — — 32.2 — 859.6 4 to 5 Category 259.5 0.6 2.0 — — 78.6 37.2 1.8 379.7 6 to 9 Category 0.7 23.1 — — — — 177.9 — 201.7 Total Non-U.S. 1,051.0 39.6 12.0 10.7 — 78.6 247.3 1.8 1,441.0 Lease Financing, net Risk Rating: 1 to 3 Category — — — — — 18.5 — — 18.5 4 to 5 Category — — — — — 11.6 — — 11.6 6 to 9 Category — — — — — — — — — Total Lease Financing, net — — — — — 30.1 — — 30.1 Other Risk Rating: 1 to 3 Category 97.7 — — — — — — — 97.7 4 to 5 Category 115.3 — — — — — — — 115.3 6 to 9 Category — — — — — — — — — Total Other 213.0 — — — — — — — 213.0 Total Commercial 2,980.3 2,344.3 1,037.3 794.0 844.3 1,301.1 5,203.9 76.5 14,581.7 Personal Private Client Risk Rating: 1 to 3 Category 466.3 394.3 56.8 67.6 34.2 150.2 5,087.1 126.1 6,382.6 4 to 5 Category 468.4 493.6 129.6 60.0 78.1 80.9 3,952.3 145.7 5,408.6 6 to 9 Category 5.6 0.5 22.4 3.2 — — 62.1 8.0 101.8 Total Private Client 940.3 888.4 208.8 130.8 112.3 231.1 9,101.5 279.8 11,893.0 Residential Real Estate Risk Rating: 1 to 3 Category 1,322.9 396.2 60.9 108.9 254.2 738.0 188.2 1.5 3,070.8 4 to 5 Category 619.8 342.5 126.6 184.2 233.8 904.6 270.2 7.4 2,689.1 6 to 9 Category 13.1 9.4 1.7 0.5 2.7 108.7 32.3 — 168.4 Total Residential Real Estate 1,955.8 748.1 189.2 293.6 490.7 1,751.3 490.7 8.9 5,928.3 Non-U.S. Risk Rating: 1 to 3 Category 8.6 21.5 — — — 1.8 28.2 — 60.1 4 to 5 Category 12.8 22.7 11.9 0.5 0.5 8.2 216.7 5.1 278.4 6 to 9 Category — — — — — 0.2 — — 0.2 Total Non-U.S. 21.4 44.2 11.9 0.5 0.5 10.2 244.9 5.1 338.7 Other Risk Rating: 1 to 3 Category 5.5 — — — — — — — 5.5 4 to 5 Category 19.1 — — — — — — — 19.1 6 to 9 Category — — — — — — — — — Total Other 24.6 — — — — — — — 24.6 Total Personal 2,942.1 1,680.7 409.9 424.9 603.5 1,992.6 9,837.1 293.8 18,184.6 Total Loans and Leases $ 5,922.4 $ 4,025.0 $ 1,447.2 $ 1,218.9 $ 1,447.8 $ 3,293.7 $ 15,041.0 $ 370.3 $ 32,766.3 Loans and leases in the “1 to 3” category are expected to exhibit minimal to modest probabilities of default and are characterized by borrowers having the strongest financial qualities, including above average financial flexibility, cash flows and capital levels. Borrowers assigned these ratings are anticipated to experience very little to moderate financial pressure in adverse down-cycle scenarios. As a result of these characteristics, borrowers within this category exhibit a minimal to modest likelihood of loss. Loans and leases in the “4 to 5” category are expected to exhibit moderate to acceptable probabilities of default and are characterized by borrowers with less financial flexibility than those in the “1 to 3” category. Cash flows and capital levels are generally sufficient to allow for borrowers to meet current requirements, but have fewer financial resources to manage through economic downturns. As a result of these characteristics, borrowers within this category exhibit a moderate likelihood of loss. Loans and leases in the watch list category have elevated credit risk profiles that are monitored through internal watch lists, and consist of credits with borrower ratings of “6 to 9.” These credits, which include all nonaccrual credits, are expected to exhibit minimally acceptable probabilities of default, elevated risk of default, or are currently in default. Borrowers associated with these risk profiles that are not currently in default have limited financial flexibility. Cash flows and capital levels range from acceptable to potentially insufficient to meet current requirements, particularly in adverse down cycle scenarios. As a result of these characteristics, borrowers in this category exhibit an elevated to probable likelihood of loss. For credit quality indicator information that was required under the former provisions of ASC Topic 310, please refer to Note 6 — Loans and Leases included under Item 8. Financial Statements and Supplementary Data in the Annual Report on Form 10-K for the year ended December 31, 2019. Past Due Status. Past due status is based on the length of time from the contractual due date a principal or interest payment has been past due. For disclosure purposes, loans and leases that are 29 days past due or less are reported as current. The following table provides balances and delinquency status of accrual and nonaccrual loans and leases by segment and class, as well as the other real estate owned and nonaccrual asset balances, as of September 30, 2020 and December 31, 2019. TABLE 51: DELINQUENCY STATUS ACCRUAL NONACCRUAL WITH NO ALLOWANCE (In Millions) CURRENT 30 – 59 DAYS 60 – 89 DAYS 90 DAYS TOTAL ACCRUAL NONACCRUAL TOTAL LOANS September 30, 2020 Commercial Commercial and Institutional $ 9,470.9 $ 21.9 $ 0.2 $ 0.8 $ 9,493.8 $ 30.2 $ 9,524.0 $ 11.5 Commercial Real Estate 3,361.0 0.6 8.1 — 3,369.7 3.9 3,373.6 3.9 Non-U.S. 1,441.0 — — — 1,441.0 — 1,441.0 — Lease Financing, net 30.1 — — — 30.1 — 30.1 — Other 213.0 — — — 213.0 — 213.0 — Total Commercial 14,516.0 22.5 8.3 0.8 14,547.6 34.1 14,581.7 15.4 Personal Private Client 11,832.8 39.4 13.3 7.5 11,893.0 — 11,893.0 — Residential Real Estate 5,859.9 2.9 1.3 0.3 5,864.4 63.9 5,928.3 55.5 Non-U.S. 338.7 — — — 338.7 — 338.7 — Other 24.6 — — — 24.6 — 24.6 — Total Personal 18,056.0 42.3 14.6 7.8 18,120.7 63.9 18,184.6 55.5 Total Loans and Leases $ 32,572.0 $ 64.8 $ 22.9 $ 8.6 $ 32,668.3 $ 98.0 $ 32,766.3 $ 70.9 Other Real Estate Owned $ 0.9 Total Nonaccrual Assets $ 98.9 ACCRUAL NONACCRUAL WITH NO ALLOWANCE (In Millions) CURRENT 30 – 59 DAYS 60 – 89 DAYS 90 DAYS TOTAL ACCRUAL NONACCRUAL TOTAL LOANS December 31, 2019 Commercial Commercial and Institutional $ 9,068.3 $ 4.1 $ 9.9 $ 1.2 $ 9,083.5 $ 7.6 $ 9,091.1 $ 0.8 Commercial Real Estate 3,089.6 2.3 4.1 4.7 3,100.7 3.6 3,104.3 2.4 Non-U.S. 1,576.3 — — — 1,576.3 — 1,576.3 — Lease Financing, net 65.6 — — — 65.6 — 65.6 — Other 164.0 — — — 164.0 — 164.0 — Total Commercial 13,963.8 6.4 14.0 5.9 13,990.1 11.2 14,001.3 3.2 Personal Private Client 11,027.9 33.2 9.5 0.3 11,070.9 0.5 11,071.4 0.5 Residential Real Estate 5,997.7 19.8 4.9 1.2 6,023.6 71.4 6,095.0 66.4 Non-U.S 174.1 0.2 — — 174.3 0.5 174.8 0.5 Other 67.1 — — — 67.1 — 67.1 — Total Personal 17,266.8 53.2 14.4 1.5 17,335.9 72.4 17,408.3 67.4 Total Loans and Leases $ 31,230.6 $ 59.6 $ 28.4 $ 7.4 $ 31,326.0 $ 83.6 $ 31,409.6 $ 70.6 Other Real Estate Owned $ 3.2 Total Nonaccrual Assets $ 86.8 Recognition of Income. Interest income on loans and leases is recorded on an accrual basis unless, in the opinion of management, there is a question as to the ability of the debtor to meet the terms of the loan agreement, or interest or principal is more than 90 days contractually past due and the loan is not well-secured and in the process of collection. Loans meeting such criteria are classified as nonaccrual and interest income is recorded on a cash basis. At the time a loan is determined to be nonaccrual, interest accrued but not collected is reversed against interest income in the current period. Interest collected on nonaccrual loans is applied to principal unless, in the opinion of management, collectability of principal is not in doubt. Management’s assessment of the indicators of loan and lease collectability, and its policies relative to the recognition of interest income, including the suspension and subsequent resumption of income recognition, do not meaningfully vary between loan and lease classes. Nonaccrual loans are returned to accrual status when factors indicating doubtful collectability no longer exist. Factors considered in returning a loan to accrual status are consistent across all classes of loans and leases and, in accordance with regulatory guidance, relate primarily to expected payment performance. Loans are eligible to be returned to accrual status when: (i) no principal or interest that is due is unpaid and repayment of the remaining contractual principal and interest is expected or (ii) the loan has otherwise become well-secured (possessing realizable value sufficient to discharge the debt, including accrued interest, in full) and is in the process of collection (through action reasonably expected to result in debt repayment or restoration to a current status in the near future). A loan that has not been brought fully current may be restored to accrual status provided there has been a sustained period of repayment performance (generally a minimum of six payment periods) by the borrower in accordance with the contractual terms, and Northern Trust is reasonably assured of repayment within a reasonable period of time. Additionally, a loan that has been formally restructured so as to be reasonably assured of repayment and performance according to its modified terms may be returned to accrual status, provided there was a well-documented credit evaluation of the borrower’s financial condition and prospects of repayment under the revised terms and there has been a sustained period of repayment performance (generally a minimum of six payment periods) under the revised terms. Nonaccrual Loans and Troubled Debt Restructurings (TDRs). A loan that has been modified as a concession by Northern Trust or a bankruptcy court resulting from the debtor’s financial difficulties is referred to as a troubled debt restructuring (TDR). All TDRs are reported as TDRs starting in the calendar year of their restructuring. In subsequent years, a TDR may cease being reported as a TDR if the loan was modified at a market rate and has performed according to the modified terms for at least six payment periods. A loan that has been modified at a below market rate will return to accrual status if it satisfies the six-payment-period performance requirement. The expected credit loss is measured based upon the present value of expected future cash flows, discounted at the effective interest rate based on the original contractual rate. If a loan’s contractual interest rate varies based on subsequent changes in an independent factor, such as an index or rate, the loan’s effective interest rate is calculated based on the factor as it changes over the life of the loan. Northern Trust elected not to project changes in the factor for purposes of estimating expected future cash flows. Further, Northern Trust elected not to adjust the effective interest rate for prepayments. If the loan is collateral dependent, the expected loss is measured based on the fair value of the collateral at the reporting date. If the loan valuation is less than the recorded value of the loan, either an allowance is established, or a charge-off is recorded, for the difference. Smaller balance (individually less than $1 million) homogeneous loans are collectively evaluated. Northern Trust’s accounting policies for material nonaccrual loans is consistent across all classes of loans and leases. All loans and leases with TDR modifications are evaluated for additional expected credit losses. The nature and extent of further deterioration in credit quality, including a subsequent default, is considered in the determination of an appropriate level of allowance for credit losses. Included within nonaccrual loans were $67.5 million and $54.9 million of nonaccrual TDRs, and $33.0 million and $27.7 million of accrual TDRs as of September 30, 2020 and December 31, 2019, respectively. There were $11.0 million and $8.2 million of aggregate undrawn loan commitments and standby letters of credit at September 30, 2020 and December 31, 2019, respectively, issued to borrowers with TDR modifications of loans. The following table provides, by segment and class, the number of TDR modifications of loans and leases during the three- and nine- month periods ended September 30, 2020 and 2019, and the recorded investments and unpaid principal balances as of September 30, 2020 and 2019. TABLE 52: TROUBLED DEBT RESTRUCTURINGS THREE MONTHS ENDED SEPTEMBER 30, 2020 NINE MONTHS ENDED SEPTEMBER 30, 2020 ($ In Millions) NUMBER OF RECORDED UNPAID NUMBER OF RECORDED UNPAID Commercial Commercial and Institutional 1 $ 1.0 $ 1.0 3 $ 25.3 $ 25.5 Total Commercial 1 1.0 1.0 3 25.3 25.5 Personal Residential Real Estate 10 17.4 17.5 16 18.3 18.7 Total Personal 10 17.4 17.5 16 18.3 18.7 Total Loans and Leases 11 $ 18.4 $ 18.5 19 $ 43.6 $ 44.2 Note: Period-end balances reflect all paydowns and charge-offs during the period. THREE MONTHS ENDED SEPTEMBER 30, 2019 NINE MONTHS ENDED SEPTEMBER 30, 2019 ($ In Millions) NUMBER OF RECORDED UNPAID NUMBER OF RECORDED UNPAID Commercial Commercial and Institutional — $ — $ — 1 $ 7.6 $ 8.8 Commercial Real Estate — — — 2 — — Total Commercial — — — 3 7.6 8.8 Personal Residential Real Estate 5 3.1 3.1 31 20.6 20.8 Total Personal 5 3.1 3.1 31 20.6 20.8 Total Loans and Leases 5 $ 3.1 $ 3.1 34 $ 28.2 $ 29.6 Note: Period-end balances reflect all paydowns and charge-offs during the period. TDR modifications involve extensions of term, deferrals of principal, interest rate concessions, and other modifications. Other modifications typically reflect other nonstandard terms which Northern Trust would not offer in non-troubled situations. During the three and nine months ended September 30, 2020, the TDR modifications of loans within residential real estate were extensions of term, other modifications, deferred principal, and interest rate concessions. During the three and nine months ended September 30, 2020, the TDR modifications within commercial and institutional were other modifications and extensions of term. During the three and nine months ended September 30, 2019, the TDR modifications of loans within residential real estate were extensions of term, other modifications, deferred principal and interest rate concessions. During the nine months ended September 30, 2019, the TDR modification within commercial and institutional was an other modification. There were no residential real estate loan TDR modifications during the twelve months ended June 30, 2020, which subsequently had a payment default during the three and nine months ended September 30, 2020. There were three residential real estate loan TDR modifications during the twelve months ended June 30, 2019, which subsequently had a payment default during the three and nine months ended September 30, 2019. The total recorded investment for these loans was approximately $1.6 million and the unpaid principal balance for these loans was approximately $1.7 million. Northern Trust may obtain physical possession of real estate via foreclosure on an in-substance repossession. As of September 30, 2020, Northern Trust held foreclosed real estate properties with a carrying value of $0.9 million as a result of obtaining physical possession. In addition, as of September 30, 2020, Northern Trust had loans with a carrying value of $11.7 million for which formal foreclosure proceedings were in process. TDR Relief — COVID-19. Due to the economic environment arising from the COVID-19 pandemic, there have been two forms of relief provided for classifying loans as TDRs: the Interagency Guidance (as defined below) and the CARES Act. Various banking regulators, including the Board of Governors of the Federal Reserve System, the Federal Deposit Insurance Corporation, the National Credit Union Administration, the Office of the Comptroller of the Currency, and the Consumer Financial Protection Bureau, have issued guidance in the April 7, 2020 Interagency Statement on Loan Modifications and Reporting for Financial Institutions Working with Customers Affected by the Coronavirus (revised) on loan modification treatment (Interagency Guidance) pursuant to which financial institutions can apply ASC 310-40 Receivables – Troubled Debt Restructurings by Creditors. In accordance with the Interagency Guidance, a loan modification is not considered a TDR if the modification is related to COVID-19; the borrower had been current (not more than 29 days past due) when the modification program was implemented; and the modification includes payment deferrals for not more than 6 months. Under section 4013 of the CARES Act, relief provided to lenders exempting certain loan modifications which would otherwise be classified as TDRs from such classification applies for loans that were current and existing as of December 31, 2019. The TDR relief under the CARES Act applies to COVID-19-related modifications that were made from March 1, 2020 until the earlier of (a) December 31, 2020 or (b) 60 days from the date the COVID-19 national emergency officially ends. Financial institutions may account for eligible loan modifications under the Interagency Guidance and/or the CARES Act. Northern Trust has elected to apply both the CARES Act and the Interagency Guidance, as applicable, in providing borrowers with loan modification relief in response to the COVID-19 pandemic. All other types of modifications which do not meet the CARES Act or Interagency Guidance requirements continue to be governed by existing regulations and accounting policies. The following tables provide, by segment and class, the number of total COVID-19-related loan modifications including the loan volume and deferred principal and interest balances as of September 30, 2020, for which Northern Trust applied an exemption from TDR classification that are in active deferral (loans currently in the deferral period) or completed deferral (loans that returned to their regular payment schedule). TABLE 53: COVID-19 LOAN MODIFICATIONS NOT CONSIDERED TDRS IN ACTIVE DEFERRAL STATUS SEPTEMBER 30, 2020 ($ In Millions) NUMBER OF COVID-19 RELATED MODIFICATIONS LOAN VOLUME DEFERRED PRINCIPAL AMOUNT DEFERRED INTEREST AMOUNT Commercial Commercial and Institutional 13 $ 73.2 $ 0.3 $ 0.5 Commercial Real Estate 2 7.3 — — Total Commercial 15 $ 80.5 $ 0.3 $ 0.5 Personal Private Client 2 $ 5.2 $ — $ 0.1 Residential Real Estate 53 19.3 0.3 0.3 Total Personal 55 $ 24.5 $ 0.3 $ 0.4 Total Loans 70 $ 105.0 $ 0.6 $ 0.9 TABLE 54: COVID-19 LOAN MODIFICATIONS NOT CONSIDERED TDRS THAT HAVE COMPLETED DEFERRAL SEPTEMBER 30, 2020 ($ In Millions) NUMBER OF COVID-19 RELATED MODIFICATIONS LOAN VOLUME DEFERRED PRINCIPAL AMOUNT DEFERRED INTEREST AMOUNT Commercial Commercial and Institutional 101 $ 199.7 $ 5.0 $ 1.5 Commercial Real Estate 104 472.2 2.9 3.3 Total Commercial 205 $ 671.9 $ 7.9 $ 4.8 Personal Private Client 34 $ 177.6 $ 2.3 $ 1.1 Residential Real Estate 346 184.8 0.5 2.0 Total Personal 380 $ 362.4 $ 2.8 $ 3.1 Total Loans 585 $ 1,034.3 $ 10.7 $ 7.9 Not included in the table above are 31 loans with $34.3 million in loan balances as of June 30, 2020 that had been granted payment deferrals but have since paid off. Northern Trust continues to accrue and recognize interest income during the loan deferral period, and hence has not moved these loans to nonaccrual or reported them as past due. Further, these loan balances continue to be assessed on a collective basis for purposes of measuring an allowance for expected credit losses. Collateral Dependent Financial Assets. A financial asset is collateral-dependent when the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral. Most of Northern Trust’s collateral dependent credit exposure relates to its residential real estate portfolio for which the collateral is usually the underlying real estate property. For collateral dependent financial assets, it is Northern Trust’s policy to reserve or charge-off the difference between the amortized cost basis of the loan and the value of the collateral. The collateral dependent financial asset balance as of September 30, 2020 was immaterial to Northern Trust’s financial statements.

Allowance for Credit Losses

Allowance for Credit Losses	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Allowance for Credit Losses	Allowance for Credit Losses During the first quarter of 2020, the Corporation implemented a change in the classification of certain loans and leases to specific segments to enhance the consistency of its reporting across various regulatory regimes. The allowance for credit losses as of and prior to December 31, 2019 remains unadjusted, as the impact of the reclassification on the allowance was immaterial. The Corporation adopted Accounting Standards Update (ASU) No. 2016-13, “Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments” ( ASU 2016-13 Allowance and Provision for Credit Losses. The allowance for credit losses — which represents management’s estimate of lifetime expected credit losses related to various portfolios subject to credit risk, off-balance-sheet credit exposures, and specific borrower relationships — is determined by management through a disciplined credit review process. Northern Trust measures expected credit losses of financial assets with similar risk characteristics on a collective basis. A financial asset is measured individually if it does not share similar risk characteristics with other financial assets and the related allowance is determined through an individual evaluation. Management’s estimates utilized in establishing an appropriate level of allowance for credit losses are not dependent on any single assumption. In determining an appropriate allowance level, management evaluates numerous variables, many of which are interrelated or dependent on other assumptions and estimates, and takes into consideration past events, current conditions and reasonable and supportable forecasts. The results of the credit reserve estimation methodology are reviewed quarterly by Northern Trust’s Credit Loss Reserve Committee, which receives input from Credit Risk Management, Treasury, Corporate Finance, the Economic Research group, and each of Northern Trust’s business units. The Credit Loss Reserve Committee determines the probability weights applied to each forecast approved by Northern Trust’s Macroeconomic Scenario Design Committee, and also reviews and approves qualitative adjustments to the collective allowance in line with Northern Trust’s qualitative adjustment framework. The following table provides information regarding changes in the total allowance for credit losses during the three and nine months ended September 30, 2020 and 2019. TABLE 55: CHANGES IN THE ALLOWANCE FOR CREDIT LOSSES THREE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT DEBT SECURITIES HELD TO MATURITY OTHER FINANCIAL ASSETS TOTAL Balance at Beginning of Period $ 210.2 $ 49.0 $ 6.5 $ 1.3 $ 267.0 Charge-Offs (0.8) — — — (0.8) Recoveries 1.2 — — — 1.2 Net Recoveries (Charge-Offs) 0.4 — — — 0.4 Provision for Credit Losses 4.8 (4.1) 0.4 (0.6) 0.5 Balance at End of Period $ 215.4 $ 44.9 $ 6.9 $ 0.7 $ 267.9 NINE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT DEBT SECURITIES HELD TO MATURITY OTHER FINANCIAL ASSETS TOTAL Balance at End of Prior Period $ 104.5 $ 19.9 $ — $ — $ 124.4 Cumulative Effect Adjustment (2.2) 8.9 6.6 0.4 13.7 Balance at Beginning of Period 102.3 28.8 6.6 0.4 138.1 Charge-Offs (3.0) — — — (3.0) Recoveries 5.3 — — — 5.3 Net Recoveries (Charge-Offs) 2.3 — — — 2.3 Provision for Credit Losses 110.8 16.1 0.3 0.3 127.5 Balance at End of Period $ 215.4 $ 44.9 $ 6.9 $ 0.7 $ 267.9 THREE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT TOTAL Balance at Beginning of Period $ 110.8 $ 23.3 $ 134.1 Charge-Offs (1.1) — (1.1) Recoveries 1.7 — 1.7 Net Recoveries (Charge-Offs) 0.6 — 0.6 Provision for Credit Losses (5.7) (1.3) (7.0) Balance at End of Period $ 105.7 $ 22.0 $ 127.7 NINE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT TOTAL Balance at Beginning of Period $ 112.6 $ 25.6 $ 138.2 Charge-Offs (2.7) — (2.7) Recoveries 5.7 — 5.7 Net Recoveries (Charge-Offs) 3.0 — 3.0 Provision for Credit Losses (9.9) (3.6) (13.5) Balance at End of Period $ 105.7 $ 22.0 $ 127.7 The portion of the allowance assigned to loans and leases, debt securities held to maturity, and other financial assets is presented as a contra asset in Allowance for Credit Losses on the consolidated balance sheets. The portion of the allowance assigned to undrawn loan commitments and standby letters of credit is reported in Other Liabilities on the consolidated balance sheets. For credit exposure and the associated allowance related to fee receivables, please refer to Note 14 — Revenue from Contracts with Clients. For information related to the allowance for debt securities available for sale, please refer to Note 4 — Securities. For all other financial assets recognized at amortized cost, which include Cash and Due from Banks, Other Central Bank Deposits, Interest Bearing Deposits with Banks, Federal Funds Sold, and Other Assets, please refer to the Allowance for Other Financial Assets section within this footnote. The Provision for Credit Losses on the consolidated statements of income represents the change in the Allowance for Credit Losses and is the charge to current period earnings that is determined by management, through a disciplined credit review process, to be the amount needed to maintain the Allowance for Credit Losses at an appropriate level to absorb lifetime expected credit losses related to financial assets in scope. Actual losses may vary from current estimates and the amount of the Provision for Credit Losses may be either greater than or less than actual net charge-offs. There was a $0.5 million Provision for Credit Losses in the current quarter as calculated under the Current Expected Credit Losses (CECL) methodology, as compared to a $7.0 million credit provision in the prior-year quarter calculated under the previous “incurred loss” model. There were net recoveries of $0.4 million during the three months ended September 30, 2020, as compared to net recoveries of $0.6 million for the three months ended September 30, 2019. The provision in the current quarter was primarily due to an increase in the reserve evaluated on a collective basis, which relates to pooled financial assets sharing similar risk characteristics. The increase in the collective basis reserve was driven by projected economic conditions resulting from the ongoing COVID-19 pandemic and related market and economic impacts, with increases in the private client, commercial real estate, and residential real estate portfolios, partially offset by a decrease in the commercial and institutional portfolio. The overall increase in the reserve on a collective basis was partially offset by a decrease in the reserve associated with loans evaluated on an individual basis. There was a $127.5 million Provision for Credit Losses for the nine months ended September 30, 2020 as calculated under the CECL methodology, as compared to a $13.5 million credit provision in the prior-year period calculated under the previous “incurred loss” model. There were net recoveries of $2.3 million during the nine months ended September 30, 2020, as compared to net recoveries of $3.0 million for the nine months ended September 30, 2019. The provision in the current period was primarily due to an increase in the reserve evaluated on a collective basis driven by downgrades in the portfolio and current and projected economic conditions, both resulting from the ongoing COVID-19 pandemic and related market and economic impacts, with the largest increases in the commercial and institutional and commercial real estate portfolios. Forecasting and Reversion. Estimating expected lifetime credit losses requires the consideration of the effect of future economic conditions. Northern Trust employs multiple scenarios over a reasonable and supportable period (currently two years) to project future conditions. Management determines the probability weights assigned to each scenario at each quarter-end. Key variables determined to be relevant for projecting credit losses on the portfolios in scope include macroeconomic factors, such as corporate profits, unemployment, and real estate price indices, as well as financial market factors such as equity prices, volatility, and credit spreads. For periods beyond the reasonable and supportable period, Northern Trust reverts to its own historical loss experiences on a straight-line basis over four quarters. Contractual Term. Northern Trust estimates expected credit losses over the contractual term of the financial assets adjusted for prepayments, unless prepayments are not relevant to specific portfolios or sub-portfolios. Extension and renewal options are typically not considered since it is not Northern Trust’s practice to enter into arrangements where the borrower has the unconditional option to renew, or a conditional extension option whereby the conditions are beyond Northern Trust’s control. Accrued Interest. Accrued interest balances are reported within Other Assets on the consolidated balance sheets. Northern Trust elected not to measure an allowance for credit losses for accrued interest receivables related to its loan and securities portfolio as its policy is to write-off uncollectible accrued interest receivable balances in a timely manner. Accrued interest is written off by reversing interest income during the quarter the financial asset is moved from an accrual to a nonaccrual status. The following table provides the amount of accrued interest excluded from the amortized cost basis of the following portfolios. TABLE 56: ACCRUED INTEREST (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Loans and Leases $ 54.2 $ 84.5 Debt Securities Held to Maturity $ 71.7 $ 82.3 Available for Sale 101.0 119.0 Other Financial Assets $ 1.7 $ 14.7 The following table provides amounts of accrued interest reversed through interest income by segment for the loan and lease portfolio. TABLE 57: ACCRUED INTEREST REVERSED THROUGH INCOME THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2020 Commercial $ 0.5 $ 1.5 Personal 0.6 $ 2.0 Total Loans and Leases $ 1.1 $ 3.5 Interest income that would have been recorded for nonaccrual loans and leases in accordance with their original terms was $1.8 million for the three months ended September 30, 2019 and $5.7 million for the nine months ended September 30, 2019. There was no accrued interest reversed through interest income related to any other financial assets for the three and nine months ended September 30, 2020 and 2019. Allowance for the Loan and Lease Portfolio. The following table provides information regarding changes in the total allowance for credit losses, including undrawn loan commitments and standby letters of credit, by segment during the three and nine months ended September 30, 2020 and 2019. TABLE 58: CHANGES IN THE ALLOWANCE FOR CREDIT LOSSES RELATED TO LOANS AND LEASES THREE MONTHS ENDED SEPTEMBER 30, 2020 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at Beginning of Period $ 162.8 $ 47.4 $ 210.2 $ 46.1 $ 2.9 $ 49.0 Charge-Offs — (0.8) (0.8) — — — Recoveries 0.2 1.0 1.2 — — — Net Recoveries (Charge-Offs) 0.2 0.2 0.4 — — — Provision for Credit Losses (15.4) 20.2 4.8 (6.0) 1.9 (4.1) Balance at End of Period $ 147.6 $ 67.8 $ 215.4 $ 40.1 $ 4.8 $ 44.9 NINE MONTHS ENDED SEPTEMBER 30, 2020 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at End of Prior Period $ 58.1 $ 46.4 $ 104.5 $ 15.8 $ 4.1 $ 19.9 Cumulative Effect Adjustment (5.9) 3.7 (2.2) 11.9 (3.0) 8.9 Balance at Beginning of Period 52.2 50.1 102.3 27.7 1.1 28.8 Charge-Offs (0.1) (2.9) (3.0) — — — Recoveries 2.2 3.1 5.3 — — — Net Recoveries (Charge-Offs) 2.1 0.2 2.3 — — — Provision for Credit Losses 93.3 17.5 110.8 12.4 3.7 16.1 Balance at End of Period $ 147.6 $ 67.8 $ 215.4 $ 40.1 $ 4.8 $ 44.9 THREE MONTHS ENDED SEPTEMBER 30, 2019 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at Beginning of Period $ 59.9 $ 50.9 $ 110.8 $ 18.5 $ 4.8 $ 23.3 Charge-Offs — (1.1) (1.1) — — — Recoveries — 1.7 1.7 — — — Net Recoveries (Charge-Offs) — 0.6 0.6 — — — Provision for Credit Losses (1.3) (4.4) (5.7) (0.7) (0.6) (1.3) Balance at End of Period $ 58.6 $ 47.1 $ 105.7 $ 17.8 $ 4.2 $ 22.0 NINE MONTHS ENDED SEPTEMBER 30, 2019 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at Beginning of Period $ 57.6 $ 55.0 $ 112.6 $ 21.1 $ 4.5 $ 25.6 Charge-Offs (0.1) (2.6) (2.7) — — — Recoveries 0.7 5.0 5.7 — — — Net Recoveries (Charge-Offs) 0.6 2.4 3.0 — — — Provision for Credit Losses 0.4 (10.3) (9.9) (3.3) (0.3) (3.6) Balance at End of Period $ 58.6 $ 47.1 $ 105.7 $ 17.8 $ 4.2 $ 22.0 The increase to the allowance for loans and leases for the three months ended September 30, 2020 was primarily due to an increase in the reserve evaluated on a collective basis, which relates to pooled financial assets sharing similar risk characteristics. The increase in the collective basis reserve was driven by projected economic conditions resulting from the ongoing COVID-19 pandemic and related market and economic impacts, with increases in the private client, commercial real estate, and residential real estate portfolios, partially offset by a decrease in the commercial and institutional portfolio. The overall increase in the reserve on a collective basis was partially offset by a decrease in the reserve associated with loans evaluated on an individual basis. The decrease to the allowance for undrawn loan commitments and standby letters of credit for the three months ended September 30, 2020 was primarily due to a decrease in the reserve evaluated on a collective basis driven by projected economic conditions resulting from the ongoing COVID-19 pandemic with decreases in the non-U.S commercial and commercial and institutional portfolios, partially offset by increases in the private client portfolio. The increase to the allowance for both loans and leases and undrawn loan commitments and standby letters of credit for the nine months ended September 30, 2020 was primarily due to an increase in the reserve evaluated on a collective basis driven by downgrades in the portfolio and current and projected economic conditions, both resulting from the ongoing COVID-19 pandemic and related market and economic impacts, with the largest increases in the commercial and institutional and commercial real estate portfolios. Allowance Related to Credit Exposure Evaluated on a Collective Level. Expected credit losses are measured on a collective basis as long as the financial assets included in the respective pool share similar risk characteristics. If financial assets are deemed to not share similar risk characteristics, an individual assessment is warranted. The allowance estimation methodology for the collective assessment is primarily based on internally developed loss data specific to the Northern Trust financial asset portfolio from a historical observation period that includes both expansionary and recessionary periods. The estimation methodology and the related qualitative adjustment framework segregate the loan and lease portfolio into homogenous segments based on similar risk characteristics or risk monitoring methods. Northern Trust utilizes a quantitative probability of default/loss given default approach for the calculation of its credit allowance on a collective basis. For each of the different parameters, specific credit models for the individual loan segments were developed. For each segment, the probability of default and the loss given default are applied to the exposure at default for each projected quarter to determine the quantitative component of the allowance. The quantitative allowance is then reviewed within the qualitative adjustment framework, through which management applies judgment by assessing internal risk factors, potential limitations in the quantitative methodology, and environmental factors that are not fully contemplated in the forecast to compute an adjustment to the quantitative allowance for each segment of the loan portfolio. Allowance Related to Credit Exposure Evaluated on an Individual Level. The allowance is determined through an individual evaluation of loans, leases, and lending-related commitments considered impaired that is based on expected future cash flows, the value of collateral, and other factors that may impact the borrower’s ability to pay. For impaired loans for which the amount of allowance, if any, is determined based on the value of the underlying real estate collateral, third-party appraisals are typically obtained and utilized by management. These appraisals are generally less than twelve months old and are subject to adjustments to reflect management’s judgment as to the realizable value of the collateral. The following table provides information regarding the recorded investments in loans and leases and the allowance for credit losses for loans and leases and undrawn loan commitments and standby letters of credit by segment as of September 30, 2020 and December 31, 2019. TABLE 59: RECORDED INVESTMENTS IN LOANS AND LEASES SEPTEMBER 30, 2020 DECEMBER 31, 2019 (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Loans and Leases Evaluated on an Individual Level $ 34.1 $ 63.9 $ 98.0 $ 10.4 $ 81.8 $ 92.2 Evaluated on a Collective Level 14,547.6 18,120.7 32,668.3 13,990.9 17,326.5 31,317.4 Total Loans and Leases 14,581.7 18,184.6 32,766.3 14,001.3 17,408.3 31,409.6 Allowance for Credit Losses on Credit Exposures Evaluated on an Individual Level 5.6 0.4 6.0 3.4 1.6 5.0 Evaluated on a Collective Level 142.0 67.4 209.4 54.7 44.8 99.5 Allowance Assigned to Loans and Leases 147.6 67.8 215.4 58.1 46.4 104.5 Allowance for Undrawn Loan Commitments and Standby Letters of Credit Evaluated on an Individual Level 2.2 — 2.2 1.9 — 1.9 Evaluated on a Collective Level 37.9 4.8 42.7 13.9 4.1 18.0 Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit 40.1 4.8 44.9 15.8 4.1 19.9 Total Allowance Assigned to Loans and Leases and Undrawn Loan Commitments and Standby Letters of Credit $ 187.7 $ 72.6 $ 260.3 $ 73.9 $ 50.5 $ 124.4 Northern Trust analyzes its exposure to credit losses from both on-balance-sheet and off-balance-sheet activity using a consistent methodology for the quantitative framework as well as the qualitative framework. For purposes of estimating the allowance for credit losses for undrawn loan commitments and standby letters of credit, the exposure at default includes an estimated drawdown of unused credit based on credit utilization factors, resulting in a proportionate amount of expected credit losses. Allowance for Debt Securities Held to Maturity Securities Portfolio. The following table provides information regarding changes in the total allowance for credit losses for debt securities held to maturity during the three and nine months ended September 30, 2020. TABLE 60: CHANGES IN THE ALLOWANCE FOR CREDIT LOSSES RELATED TO DEBT SECURITIES HELD TO MATURITY THREE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) CORPORATE DEBT NON-U.S. GOVERNMENT SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS CERTIFICATE OF DEPOSITS COVERED BONDS OTHER TOTAL Balance at Beginning of Period $ 0.5 $ 0.4 $ 0.7 $ — $ — $ 4.9 $ 6.5 Provision for Credit Losses 0.2 — (0.1) 0.2 0.1 — 0.4 Balance at End of Period $ 0.7 $ 0.4 $ 0.6 $ 0.2 $ 0.1 $ 4.9 $ 6.9 NINE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) CORPORATE DEBT NON-U.S. GOVERNMENT SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS CERTIFICATE OF DEPOSITS COVERED BONDS OTHER TOTAL Balance at End of Prior Period $ — $ — $ — $ — $ — $ — $ — Cumulative Effect Adjustment 0.8 0.3 0.9 — — 4.6 6.6 Balance at Beginning of Period 0.8 0.3 0.9 — — 4.6 6.6 Provision for Credit Losses (0.1) 0.1 (0.3) 0.2 0.1 0.3 0.3 Balance at End of Period $ 0.7 $ 0.4 $ 0.6 $ 0.2 $ 0.1 $ 4.9 $ 6.9 Prior to the adoption of ASU 2016-13, Northern Trust recognized $4.4 million of cumulative Other-Than-Temporary-Impairment (OTTI) losses on the debt securities classified as other as of December 31, 2019. For debt securities with previous OTTI losses recorded, Northern Trust applied ASU 2016-13 on a prospective basis whereby the amortized cost basis of the impaired security remains unchanged immediately before and after adopting ASU 2016-13. The allowance recorded at January 1, 2020 for debt securities held to maturity equals the difference between the calculated expected loss and the amount of OTTI loss previously recorded and represents the cumulative effect adjustment required upon the adoption of ASU 2016-13. The increase to the allowance attributable to debt securities held to maturity for the three and nine months ended September 30, 2020 was primarily due to an increase in the reserve evaluated on a collective basis driven by current and projected economic conditions resulting from the ongoing COVID-19 pandemic and related market and economic impacts. The allowance for credit losses for Northern Trust’s debt securities held to maturity portfolio is evaluated as follows: • Debt securities held to maturity classified as U.S. government, government sponsored agency, and certain securities classified as obligations of states and political subdivisions are considered to be guarantees of the U.S. government or an agency of the U.S. government and therefore an allowance for credit losses is not estimated for such investments as the expected probability of non-payment of the amortized cost basis is zero. • Debt securities held to maturity classified as other asset-backed represent pools of underlying receivables from which the cash flows are used to pay the bonds that vary in seniority. Utilizing a qualitative estimation approach, the allowance for other asset-backed securities is assessed by evaluating underlying pool performance based on delinquency rates and available credit support. • Debt securities held to maturity classified as other relates to investments purchased by Northern Trust to fulfill its obligations under the Community Reinvestment Act (CRA). Northern Trust fulfills its obligations under the CRA by making qualified investments for purposes of supporting institutions and programs that benefit low-to-moderate income communities within Northern Trust’s market area. The allowance for CRA investments is assessed using a qualitative estimation approach primarily based on internal historical performance experience and default history of the underlying CRA portfolios to determine a quantitative component of the allowance. The allowance estimation methodology for all other debt securities held to maturity is developed using a combination of external and internal data. The estimation methodology groups securities with shared characteristics for which the probability of default and the loss given default are applied to the total exposure at default to determine a quantitative component of the allowance. Allowance for Other Financial Assets. The allowance for Other Financial Assets consists of the allowance for Cash and Due from Banks, Other Central Bank Deposits, Interest Bearing Deposits with Banks, Federal Funds Sold, and Other Assets. The Other Assets category includes other miscellaneous credit exposures reported in Other Assets on the consolidated balance sheets. The allowance estimation methodology for Other Financial Assets primarily utilizes a similar approach as used for the Debt Securities Held to Maturity portfolio. It consists of a combination of externally and internally developed loss data, adjusted for the appropriate contractual term. Northern Trust’s portfolio is composed mostly of institutions within the “1 to 3” internal borrower rating category and expected to exhibit minimal to modest likelihood of loss. The allowance for credit losses related to Other Financial Assets was $0.7 million as of September 30, 2020.

Pledged Assets

Pledged Assets	9 Months Ended
	Sep. 30, 2020
Transfers and Servicing [Abstract]
Pledged Assets	Pledged Assets Certain of Northern Trust’s subsidiaries, as required or permitted by law, pledge assets to secure public and trust deposits, repurchase agreements and borrowings, as well as for other purposes, including support for securities settlement, primarily related to client activities, and for derivative contracts. The following table presents Northern Trust's pledged assets. TABLE 61: TYPE OF PLEDGED ASSETS (In Billions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Securities Obligations of States and Political Subdivisions $ 1.6 $ 1.0 Government Sponsored Agency and Other Securities 30.0 33.4 Loans 11.8 7.7 Total Pledged Assets $ 43.4 $ 42.1 Collateral required for these purposes totaled $7.6 billion and $8.5 billion at September 30, 2020 and December 31, 2019, respectively. The following table presents the available for sale debt securities pledged as collateral that are included in pledged assets. TABLE 62: FAIR VALUE OF AVAILABLE FOR SALE DEBT SECURITIES INCLUDED IN PLEDGED ASSETS SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE DERIVATIVE CONTRACTS (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 SEPTEMBER 30, 2020 DECEMBER 31, 2019 Debt Securities Available for Sale $ 268.6 $ 487.1 $ 30.0 $ 14.4 The secured parties to these transactions have the right to repledge or sell the securities as it relates to $268.6 million and $487.2 million of the pledged collateral as of September 30, 2020 and December 31, 2019, respectively. Northern Trust accepts financial assets as collateral that it is and is not permitted to repledge or sell. The collateral is generally obtained under certain reverse repurchase agreements and derivative contracts. The following table presents the fair value of securities accepted as collateral. There was no repledged or sold collateral at September 30, 2020 or December 31, 2019. TABLE 63: ACCEPTED COLLATERAL (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Collateral that may be repledged or sold Reverse repurchase agreements $ 1,533.4 $ 707.8 Derivative contracts 30.6 16.8

Goodwill and Other Intangibles

Goodwill and Other Intangibles	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other Intangibles Goodwill. Changes by reporting segment in the carrying amount of goodwill for the nine months ended September 30, 2020, including the effect of foreign exchange rates on non-U.S.-dollar denominated balances, were as follows: TABLE 64: GOODWILL BY REPORTING SEGMENT (In Millions) CORPORATE & INSTITUTIONAL SERVICES WEALTH MANAGEMENT TOTAL Balance at December 31, 2019 $ 625.7 $ 71.1 $ 696.8 Foreign Exchange Rates 1.2 — 1.2 Balance at September 30, 2020 $ 626.9 $ 71.1 $ 698.0 Other Intangible Assets Subject to Amortization . The gross carrying amount and accumulated amortization of other intangible assets subject to amortization as of September 30, 2020 and December 31, 2019 were as follows: TABLE 65: OTHER INTANGIBLE ASSETS (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Gross Carrying Amount $ 214.3 $ 207.2 Less: Accumulated Amortization 101.7 86.6 Net Book Value $ 112.6 $ 120.6 Other intangible assets consist primarily of the value of acquired client relationships and are included within Other Assets on the consolidated balance sheets. Amortization expense related to other intangible assets totaled $4.3 million and $12.6 million for the three and nine months ended September 30, 2020, and $4.2 million and $12.5 million for the three and nine months ended September 30, 2019. Amortization for the remainder of 2020 and for the years 2021, 2022, 2023, and 2024 is estimated to be $4.3 million, $14.7 million, $10.1 million, $9.8 million, and $9.7 million, respectively.

Reporting Segments

Reporting Segments	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Reporting Segments	Reporting Segments Northern Trust is organized around its two client-focused reporting segments: Corporate & Institutional Services (C&IS) and Wealth Management. Asset management and related services are provided to C&IS and Wealth Management clients primarily by the Asset Management business. The revenue and expenses of Asset Management and certain other support functions are allocated fully to C&IS and Wealth Management. Reporting segment financial information, presented on an internal management-reporting basis, is determined by accounting systems used to allocate revenue and expense to each segment, and incorporates processes for allocating assets, liabilities, equity and the applicable interest income and expense utilizing a funds transfer pricing (FTP) methodology. Under the methodology, assets and liabilities receive a funding charge or credit that considers interest rate risk, liquidity risk, and other product characteristics on an instrument level. Revenues, expenses and average assets are allocated to C&IS and Wealth Management, with the exception of non-recurring activities such as certain costs associated with acquisitions, divestitures, litigation, restructuring, and tax adjustments not directly attributable to a specific reporting segment. Reporting segment results are subject to reclassification when organizational changes are made. The results are also subject to refinements in revenue and expense allocation methodologies, which are typically reflected on a prospective basis. The following table reflects the earnings contributions and average assets of Northern Trust’s reporting segments for the three- and nine- month periods ended September 30, 2020 and 2019. TABLE 66: RESULTS OF REPORTING SEGMENTS ($ In Millions) CORPORATE & WEALTH MANAGEMENT TREASURY AND OTHER TOTAL CONSOLIDATED THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 2020 2019 Noninterest Income Trust, Investment and Other Servicing Fees $ 584.9 $ 559.9 $ 418.9 $ 415.6 $ — $ — $ 1,003.8 $ 975.5 Foreign Exchange Trading Income 58.4 55.5 3.2 4.2 — — 61.6 59.7 Other Noninterest Income 56.7 53.6 39.7 38.1 (5.3) (6.7) 91.1 85.0 Total Noninterest Income 700.0 669.0 461.8 457.9 (5.3) (6.7) 1,156.5 1,120.2 Net Interest Income (1) 139.9 229.9 196.6 195.4 — — 336.5 425.3 Revenue (1) 839.9 898.9 658.4 653.3 (5.3) (6.7) 1,493.0 1,545.5 Provision for Credit Losses (19.2) 4.8 19.7 (11.8) — — 0.5 (7.0) Noninterest Expense 707.3 649.2 386.3 385.9 1.1 1.2 1,094.7 1,036.3 Income before Income Taxes (1) 151.8 244.9 252.4 279.2 (6.4) (7.9) 397.8 516.2 Provision for Income Taxes (1) 38.7 59.9 66.2 73.6 (1.6) (1.9) 103.3 131.6 Net Income $ 113.1 $ 185.0 $ 186.2 $ 205.6 $ (4.8) $ (6.0) $ 294.5 $ 384.6 Percentage of Consolidated Net Income 39 % 48 % 63 % 54 % (2) % (2) % 100 % 100 % Average Assets $ 108,823.0 $ 85,982.2 $ 32,102.4 $ 30,369.9 $ — $ — $ 140,925.4 $ 116,352.1 (1) Non-GAAP financial measures stated on a fully taxable equivalent basis (FTE). Total consolidated includes FTE adjustments of $7.9 million for 2020 and $7.6 million for 2019. ($ In Millions) CORPORATE & WEALTH MANAGEMENT TREASURY AND OTHER TOTAL CONSOLIDATED NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 2020 2019 Noninterest Income Trust, Investment and Other Servicing Fees $ 1,725.5 $ 1,644.5 $ 1,243.4 $ 1,215.4 $ — $ — $ 2,968.9 $ 2,859.9 Foreign Exchange Trading Income 211.8 172.5 10.0 13.9 — — 221.8 186.4 Other Noninterest Income 167.5 141.8 122.9 95.1 (11.0) (14.9) 279.4 222.0 Total Noninterest Income 2,104.8 1,958.8 1,376.3 1,324.4 (11.0) (14.9) 3,470.1 3,268.3 Net Interest Income (1) 516.6 694.3 615.9 585.9 — — 1,132.5 1,280.2 Revenue (1) 2,621.4 2,653.1 1,992.2 1,910.3 (11.0) (14.9) 4,602.6 4,548.5 Provision for Credit Losses 35.3 1.3 92.2 (14.8) — — 127.5 (13.5) Noninterest Expense 2,022.2 1,930.5 1,152.7 1,137.9 22.3 2.8 3,197.2 3,071.2 Income before Income Taxes (1) 563.9 721.3 747.3 787.2 (33.3) (17.7) 1,277.9 1,490.8 Provision for Income Taxes (1) 129.9 171.8 187.9 202.3 (8.3) (4.4) 309.5 369.7 Net Income $ 434.0 $ 549.5 $ 559.4 $ 584.9 $ (25.0) $ (13.3) $ 968.4 $ 1,121.1 Percentage of Consolidated Net Income 45 % 49 % 58 % 52 % (3) % (1) % 100 % 100 % Average Assets $ 102,902.3 $ 87,664.1 $ 31,742.9 $ 29,700.6 $ — $ — $ 134,645.2 $ 117,364.7 (1) Non-GAAP financial measures stated on a fully taxable equivalent basis (FTE). Total consolidated includes FTE adjustments of $23.7 million for 2020 and $23.1 million for 2019.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock. The Corporation is authorized to issue 10 million shares of preferred stock without par value. The Board of Directors is authorized to fix the particular designations, preferences and relative, participating, optional and other special rights and qualifications, limitations or restrictions for each series of preferred stock issued. As of September 30, 2020, 5,000 shares of Series D Non-Cumulative Perpetual Preferred Stock (the “Series D Preferred Stock”) and 16,000 shares of Series E Non-Cumulative Perpetual Preferred Stock (“Series E Preferred Stock”) were outstanding. Series D Preferred Stock. As of September 30, 2020, the Corporation had issued and outstanding 500,000 depositary shares, each representing a 1/100th ownership interest in a share of Series D Preferred Stock, issued in August 2016. Equity related to Series D Preferred Stock as of September 30, 2020 and December 31, 2019 was $493.5 million. Shares of the Series D Preferred Stock have no par value and a liquidation preference of $100,000 (equivalent to $1,000 per depositary share). Dividends on the Series D Preferred Stock, which are not mandatory, accrue and are payable on the liquidation preference amount, on a non-cumulative basis, at a rate per annum equal to (i) 4.60% from the original issue date of the Series D Preferred Stock to but excluding October 1, 2026; and (ii) a floating rate equal to Three-Month LIBOR plus 3.202% from and including October 1, 2026. Fixed rate dividends are payable in arrears on the first day of April and October of each year, through and including October 1, 2026, and floating rate dividends will be payable in arrears on the first day of January, April, July and October of each year, commencing on January 1, 2027. On July 21, 2020, the Corporation declared a cash dividend of $2,300 per share of Series D Preferred Stock payable on October 1, 2020, to stockholders of record as of September 15, 2020. Series E Preferred Stock. As of September 30, 2020, the Corporation had issued and outstanding 16 million depositary shares, each representing 1/1,000th ownership interest in a share of Series E Preferred Stock, issued in November 2019. Equity related to Series E Preferred Stock as of September 30, 2020 and December 31, 2019 was $391.4 million. Shares of the Series E Preferred Stock have no par value and a liquidation preference of $25,000 (equivalent to $25 per depositary share). Dividends on the Series E Preferred Stock, which are not mandatory, will accrue and be payable on the liquidation preference amount, on a non-cumulative basis, quarterly in arrears on the first day of January, April, July and October of each year, commencing on April 1, 2020, at a rate per annum equal to 4.70%. On July 21, 2020, the Corporation declared a cash dividend of $293.75 per share of Series E Preferred Stock payable on October 1, 2020, to stockholders of record as of September 15, 2020. Common Stock. As the Corporation suspended its open-market share repurchase program on March 16, 2020, the only shares repurchased during the three months ended September 30, 2020 were 18,534 shares of common stock withheld upon the vesting of share-based compensation at a total cost of $1.5 million ($81.02 average price per share) to satisfy tax withholding obligations. During the nine months ended September 30, 2020, the Corporation repurchased 3,262,621 shares of common stock, including 518,745 shares withheld related to share-based compensation, at a total cost of $298.5 million ($91.49 average price per share). The Corporation’s current stock repurchase authorization to repurchase up to 25.0 million shares was approved by the Board of Directors in July 2018. Shares are repurchased by the Corporation to, among other things, manage the Corporation’s capital levels. Repurchased shares are used for general purposes, including the issuance of shares under stock option and other incentive plans. The repurchase authorization approved by the Board of Directors has no expiration date.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following tables summarize the components of accumulated other comprehensive income (loss) (AOCI) at September 30, 2020 and 2019, and changes during the three and nine months then ended. TABLE 67: SUMMARY OF CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) THREE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at June 30, 2020 $ 631.8 $ 0.3 $ 145.5 $ (407.2) $ 370.4 Net Change 33.5 1.3 1.8 17.5 54.1 Balance at September 30, 2020 $ 665.3 $ 1.6 $ 147.3 $ (389.7) $ 424.5 (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2020. NINE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at December 31, 2019 $ 114.0 $ (3.7) $ 117.8 $ (422.8) $ (194.7) Net Change 551.3 5.3 29.5 33.1 619.2 Balance at September 30, 2020 $ 665.3 $ 1.6 $ 147.3 $ (389.7) $ 424.5 (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2020. THREE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at June 30, 2019 $ 133.1 $ 4.5 $ 96.8 $ (394.2) $ (159.8) Net Change 57.0 (2.4) 9.9 4.3 68.8 Balance at September 30, 2019 $ 190.1 $ 2.1 $ 106.7 $ (389.9) $ (91.0) (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2019. NINE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at December 31, 2018 $ (114.9) $ 4.0 $ 67.9 $ (410.7) $ (453.7) Net Change 305.0 (1.9) 38.8 20.8 362.7 Balance at September 30, 2019 $ 190.1 $ 2.1 $ 106.7 $ (389.9) $ (91.0) (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2019. TABLE 68: DETAILS OF CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 (In Millions) BEFORE TAX TAX EFFECT AFTER TAX BEFORE TAX TAX EFFECT AFTER TAX Unrealized Gains (Losses) on Debt Securities Available for Sale Unrealized Gains (Losses) on Debt Securities Available for Sale $ 45.3 $ (11.8) $ 33.5 $ 76.1 $ (19.4) $ 56.7 Reclassification Adjustment for (Gains) Losses Included in Net Income (1) — — — 0.3 — 0.3 Net Change $ 45.3 $ (11.8) $ 33.5 $ 76.4 $ (19.4) $ 57.0 Unrealized Gains (Losses) on Cash Flow Hedges Foreign Exchange Contracts $ 6.6 $ (1.6) $ 5.0 $ 0.7 $ (0.2) $ 0.5 Interest Rate Contracts (0.2) — (0.2) 0.1 — 0.1 Reclassification Adjustment for (Gains) Losses Included in Net Income (2) (4.7) 1.2 (3.5) (4.0) 1.0 (3.0) Net Change $ 1.7 $ (0.4) $ 1.3 $ (3.2) $ 0.8 $ (2.4) Foreign Currency Adjustments Foreign Currency Translation Adjustments $ 92.1 $ (3.1) $ 89.0 $ (71.9) $ 2.0 $ (69.9) Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses) 1.2 (0.3) 0.9 (1.3) 0.3 (1.0) Net Investment Hedge Gains (Losses) (117.4) 29.3 (88.1) 107.6 (26.8) 80.8 Net Change $ (24.1) $ 25.9 $ 1.8 $ 34.4 $ (24.5) $ 9.9 Pension and Other Postretirement Benefit Adjustments Net Actuarial Gains $ 12.6 $ (3.1) $ 9.5 $ — $ — $ — Reclassification Adjustment for (Gains) Losses Included in Net Income (3) Amortization of Net Actuarial Loss 10.7 (2.6) 8.1 5.7 (1.3) 4.4 Amortization of Prior Service Cost (0.1) — (0.1) (0.1) — (0.1) Net Change $ 23.2 $ (5.7) $ 17.5 $ 5.6 $ (1.3) $ 4.3 Total Net Change $ 46.1 $ 8.0 $ 54.1 $ 113.2 $ (44.4) $ 68.8 See table footnotes under the YTD table. NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 (In Millions) BEFORE TAX TAX EFFECT AFTER TAX BEFORE TAX TAX EFFECT AFTER TAX Unrealized Gains (Losses) on Debt Securities Available for Sale Unrealized Gains (Losses) on Debt Securities Available for Sale $ 736.8 $ (185.4) $ 551.4 $ 409.0 $ (104.6) $ 304.4 Reclassification Adjustment for (Gains) Losses Included in Net Income (1) (0.1) — (0.1) 0.6 — 0.6 Net Change $ 736.7 $ (185.4) $ 551.3 $ 409.6 $ (104.6) $ 305.0 Unrealized Gains (Losses) on Cash Flow Hedges Foreign Exchange Contracts $ 18.1 $ (4.5) $ 13.6 $ 17.4 $ (4.3) $ 13.1 Interest Rate Contracts 0.2 (0.1) 0.1 1.4 (0.3) 1.1 Reclassification Adjustment for (Gains) Losses Included in Net Income (2) (11.2) 2.8 (8.4) (21.4) 5.3 (16.1) Net Change $ 7.1 $ (1.8) $ 5.3 $ (2.6) $ 0.7 $ (1.9) Foreign Currency Adjustments Foreign Currency Translation Adjustments $ 53.1 $ (1.0) $ 52.1 $ (69.4) $ 3.3 $ (66.1) Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses) 0.7 (0.2) 0.5 (1.3) 0.3 (1.0) Net Investment Hedge Gains (Losses) (29.8) 6.7 (23.1) 144.1 (38.2) 105.9 Net Change $ 24.0 $ 5.5 $ 29.5 $ 73.4 $ (34.6) $ 38.8 Pension and Other Postretirement Benefit Adjustments Net Actuarial Gains (Losses) $ 11.8 $ (3.0) $ 8.8 $ 11.4 $ (3.1) $ 8.3 Reclassification Adjustment for (Gains) Losses Included in Net Income (3) Amortization of Net Actuarial Loss $ 32.3 $ (7.8) $ 24.5 $ 16.8 $ (4.1) $ 12.7 Amortization of Prior Service Cost (0.2) — (0.2) (0.2) — (0.2) Net Change $ 43.9 $ (10.8) $ 33.1 $ 28.0 $ (7.2) $ 20.8 Total Net Change $ 811.7 $ (192.5) $ 619.2 $ 508.4 $ (145.7) $ 362.7 (1) The before-tax reclassification adjustment out of AOCI related to the realized gains (losses) on debt securities available for sale is recorded as Investment Security Gains (Losses), net within the consolidated statements of income. (2) See Note 20 — Derivative Financial Instruments for the location of the reclassification adjustment related to cash flow hedges. (3) The before-tax reclassification adjustment out of AOCI related to pension and other postretirement benefit adjustments is recorded in Employee Benefits expense within the consolidated statements of income.

Net Income Per Common Share Com

Net Income Per Common Share Computations	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Income Per Common Share Computations	Net Income Per Common Share Computations The computations of net income per common share are presented in the following table. TABLE 69: NET INCOME PER COMMON SHARE THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, ($ In Millions Except Per Common Share Information) 2020 2019 2020 2019 Basic Net Income Per Common Share Average Number of Common Shares Outstanding 208,106,190 213,176,809 208,351,088 215,832,347 Net Income $ 294.5 $ 384.6 $ 968.4 $ 1,121.1 Less: Dividends on Preferred Stock 16.2 17.4 51.5 40.6 Net Income Applicable to Common Stock 278.3 367.2 916.9 1,080.5 Less: Earnings Allocated to Participating Securities 3.3 4.5 10.6 12.6 Earnings Allocated to Common Shares Outstanding 275.0 362.7 906.3 1,067.9 Basic Net Income Per Common Share $ 1.32 $ 1.70 $ 4.35 $ 4.95 Diluted Net Income Per Common Share Average Number of Common Shares Outstanding 208,106,190 213,176,809 208,351,088 215,832,347 Plus: Dilutive Effect of Share-based Compensation 582,304 1,029,767 672,243 1,031,216 Average Common and Potential Common Shares 208,688,494 214,206,576 209,023,331 216,863,563 Earnings Allocated to Common and Potential Common Shares $ 275.0 $ 362.7 $ 906.3 $ 1,067.9 Diluted Net Income Per Common Share 1.32 1.69 4.34 4.92

Revenue from Contracts with Cli

Revenue from Contracts with Clients	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Clients	Revenue from Contracts with Clients Trust, Investment, and Other Servicing Fees. Custody and fund administration income is comprised of revenues received from our core asset servicing business for providing custody, fund administration, and middle-office-related services, primarily to C&IS clients. Investment management and advisory income contains revenue received from providing asset management and related services to Wealth Management and C&IS clients and to Northern Trust sponsored funds. Securities lending income represents revenues generated from securities lending arrangements that Northern Trust enters into as agent, mainly with C&IS clients. Other income largely consists of revenues received from providing employee benefit, investment risk and analytic and other services to C&IS and Wealth Management clients. Other Noninterest Income. Treasury management income represents revenues received from providing cash and liquidity management services to C&IS and Wealth Management clients. The portion of securities commissions and trading income that relates to revenue from contracts with clients is primarily comprised of commissions earned from providing securities brokerage services to Wealth Management and C&IS clients. The portion of other operating income that relates to revenue from contracts with clients is mainly comprised of service fees for banking-related services provided to Wealth Management and C&IS clients. Performance Obligations. Clients are typically charged monthly or quarterly in arrears based on the fee arrangement agreed to with each client; payment terms will vary depending on the client and services offered. Substantially all revenues generated from contracts with clients for asset servicing, asset management, securities lending, treasury management and banking-related services are recognized on an accrual basis, over the period in which services are provided. The nature of Northern Trust’s performance obligations is to provide a series of distinct services in which the customer simultaneously receives and consumes the benefits of the promised services as they are performed. Fee arrangements are mainly comprised of variable amounts based on market value of client assets managed and serviced, transaction volumes, number of accounts, and securities lending volume and spreads. Revenue is recognized using the output method in an amount that reflects the consideration to which Northern Trust expects to be entitled in exchange for providing each month or quarter of service. For contracts with multiple performance obligations, revenue is allocated to each performance obligation based on the price agreed to with the client, representing its relative standalone selling price. Security brokerage revenue is primarily represented by securities commissions received in exchange of providing trade execution related services. Control is transferred at a point in time, on the trade date of the transaction, and fees are typically variable based on transaction volumes and security types. Northern Trust’s contracts with its clients are typically open-ended arrangements and are therefore considered to have an original duration of less than one year. Northern Trust has elected the practical expedient to not disclose the value of remaining performance obligations for contracts with an original expected duration of one year or less. The following table presents revenues disaggregated by major revenue source. TABLE 70: REVENUE DISAGGREGATION THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Noninterest Income Trust, Investment and Other Servicing Fees Custody and Fund Administration $ 416.4 $ 414.8 $ 1,231.7 $ 1,219.7 Investment Management and Advisory 519.3 491.4 1,515.2 1,428.7 Securities Lending 19.8 20.1 70.7 64.9 Other 48.3 49.2 151.3 146.6 Total Trust, Investment and Other Servicing Fees $ 1,003.8 $ 975.5 $ 2,968.9 $ 2,859.9 Other Noninterest Income Foreign Exchange Trading Income $ 61.6 $ 59.7 $ 221.8 $ 186.4 Treasury Management Fees 11.6 11.2 34.0 34.1 Security Commissions and Trading Income 26.0 29.1 100.9 75.8 Other Operating Income 53.5 45.1 144.4 113.0 Investment Security Gains (Losses), net — (0.4) 0.1 (0.9) Total Other Noninterest Income $ 152.7 $ 144.7 $ 501.2 $ 408.4 Total Noninterest Income $ 1,156.5 $ 1,120.2 $ 3,470.1 $ 3,268.3 On the consolidated statements of income, Trust, Investment and Other Servicing Fees and Treasury Management Fees represent revenue from contracts with clients. For the three months ended September 30, 2020, revenue from contracts with clients also includes $21.8 million of the $26.0 million total Security Commissions and Trading Income and $10.8 million of the $53.5 million total Other Operating Income. For the nine months ended September 30, 2020, revenue from contracts with clients also included $76.9 million of the $100.9 million total Security Commissions and Trading Income and $31.6 million of the $144.4 million total Other Operating Income. For the three months ended September 30, 2019, revenue from contracts with clients also includes $23.5 million of the $29.1 million total Security Commissions and Trading Income and $10.5 million of the $45.1 million total Other Operating Income. For the nine months ended September 30, 2019, revenue from contracts with clients also included $64.3 million of the $75.8 million total Security Commissions and Trading Income and $30.9 million of the $113.0 million total Other Operating Income. Receivables Balances. The table below represents receivables balances from contracts with clients, which are included in Other Assets on the consolidated balance sheets, at September 30, 2020 and December 31, 2019. TABLE 71: CLIENT RECEIVABLES (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Trust Fees Receivable, net (1) $ 805.7 $ 801.9 Other 113.2 101.1 Total Client Receivables $ 918.9 $ 903.0 (1) Trust Fees Receivable is net of a $7.3 million and $5.6 million fee receivable allowance as of September 30, 2020 and December 31, 2019, respectively.

Net Interest Income

Net Interest Income	9 Months Ended
	Sep. 30, 2020
Banking and Thrift, Interest [Abstract]
Net Interest Income	Net Interest Income The components of net interest income were as follows: TABLE 72: NET INTEREST INCOME THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Interest Income Loans and Leases $ 167.1 $ 291.0 $ 606.4 $ 889.8 Securities — Taxable 182.6 265.9 632.1 812.4 — Non-Taxable 0.3 0.9 1.1 3.1 Interest-Bearing Due from and Deposits with Banks (1) 2.7 18.6 20.0 55.7 Federal Reserve and Other Central Bank Deposits and Other 2.7 44.4 31.3 162.8 Total Interest Income $ 355.4 $ 620.8 $ 1,290.9 $ 1,923.8 Interest Expense Deposits $ (3.5) $ 122.0 $ 56.7 $ 403.5 Federal Funds Purchased 0.1 2.4 2.1 22.8 Securities Sold Under Agreements to Repurchase — 1.6 1.0 5.4 Other Borrowings 5.0 46.0 40.6 145.2 Senior Notes 19.1 19.6 57.0 54.0 Long-Term Debt 5.7 9.4 21.1 29.4 Floating Rate Capital Debt 0.4 2.1 3.6 6.4 Total Interest Expense $ 26.8 $ 203.1 $ 182.1 $ 666.7 Net Interest Income $ 328.6 $ 417.7 $ 1,108.8 $ 1,257.1 (1) Interest-Bearing Due from and Deposits with Banks includes the interest-bearing component of Cash and Due from Banks and Interest-Bearing Deposits with Banks as presented on the consolidated balance sheets.

Pension and Postretirement Heal

Pension and Postretirement Health Care	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
Pension and Postretirement Health Care	Pension and Postretirement Health Care The following table sets forth the net periodic pension and postretirement benefit expense for Northern Trust’s U.S. Qualified Plan, Non-U.S. Pension Plans, U.S. Non-Qualified Plan, and postretirement health care plan for the three and nine months ended September 30, 2020 and 2019. TABLE 73: NET PERIODIC PENSION EXPENSE (BENEFIT) U.S. QUALIFIED PLAN THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Service Cost $ 11.9 $ 10.4 $ 35.5 $ 31.2 Interest Cost 10.8 11.8 32.4 35.4 Expected Return on Plan Assets (19.2) (21.7) (57.6) (65.1) Amortization Net Actuarial Loss 8.8 4.3 26.4 12.9 Prior Service Cost (0.1) (0.1) (0.3) (0.3) Net Periodic Pension Expense $ 12.2 $ 4.7 $ 36.4 $ 14.1 NON-U.S. PENSION PLANS THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Service Cost $ 0.6 $ 0.5 $ 1.6 $ 1.5 Interest Cost 0.7 0.9 2.1 2.9 Expected Return on Plan Assets (0.8) (1.0) (2.3) (2.9) Settlement Expense 0.1 — 0.3 — Amortization Net Actuarial Loss 0.2 0.2 0.8 0.5 Prior Service Cost 0.1 — 0.1 — Net Periodic Pension Expense $ 0.9 $ 0.6 $ 2.6 $ 2.0 U.S. NON-QUALIFIED PLAN THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Service Cost $ 1.2 $ 1.1 $ 3.4 $ 3.1 Interest Cost 1.2 1.5 3.6 4.4 Amortization Net Actuarial Loss 1.7 1.4 5.3 4.2 Prior Service Cost — — 0.1 0.1 Net Periodic Pension Expense $ 4.1 $ 4.0 $ 12.4 $ 11.8 POSTRETIREMENT HEALTH CARE PLAN THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Interest Cost $ 0.2 $ 0.3 $ 0.6 $ 0.9 Amortization Net Actuarial (Gain) (0.1) (0.2) (0.5) (0.8) Prior Service Cost (0.1) — (0.1) — Net Periodic Postretirement Expense $ — $ 0.1 $ — $ 0.1 Northern Trust expects to change the plan design of its post-retirement health care plan as of January 1, 2021, which results in the recognition of negative prior-service cost at the time these changes were communicated to participants in August 2020. Concurrently, a further shift in population from active to inactive participants required an adjustment to the amortization period from the average remaining service period of active participants to the average life expectancy of the inactive participants. The change in plan design and amortization period results in a decrease of the benefit obligation and 2020 benefit expense by $12.6 million and $0.3 million, respectively. The components of net periodic pension expense are recorded in Employee Benefits expense within the consolidated statements of income. There were no contributions to the U.S. Qualified Plan during the nine months ended September 30, 2020 and 2019, respectively.

Share-Based Compensation Plans

Share-Based Compensation Plans	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Share-Based Compensation Plans	Share-Based Compensation Plans The Northern Trust Corporation 2017 Long-Term Incentive Plan provides for the grant of non-qualified and incentive stock options; tandem and free-standing stock appreciation rights; stock awards in the form of restricted stock, restricted stock units and other stock awards; and performance awards. Beginning with the grants made on February 21, 2017 under the Corporation’s prior equity incentive plan, restricted stock unit and performance stock unit grants continue to vest in accordance with the original terms of the award if the applicable employee retires after satisfying applicable age and service requirements. For all applicable periods, stock option grants continue to vest in accordance with the original terms of the award if the employee meets applicable age and service requirements upon separation from service. Total compensation expense for share-based payment arrangements and the associated tax impacts were as follows for the three and nine months ended September 30, 2020 and 2019. TABLE 74: TOTAL COMPENSATION EXPENSE FOR SHARE-BASED PAYMENT ARRANGEMENTS THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Restricted Stock Unit Awards $ 12.2 $ 14.0 $ 66.3 $ 68.5 Stock Options 0.1 0.4 0.4 1.1 Performance Stock Units 1.6 2.9 16.1 21.7 Total Share-Based Compensation Expense 13.9 17.3 82.8 91.3 Tax Benefits Recognized $ 3.5 $ 4.3 $ 20.6 $ 22.7

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities Variable Interest Entities (VIEs) are defined within GAAP as entities which either have a total equity investment that is insufficient to permit the entity to finance its activities without additional subordinated financial support or whose equity investors lack the characteristics of a controlling financial interest. Investors that finance a VIE through debt or equity interests, or other counterparties that provide other forms of support, such as guarantees, subordinated fee arrangements, or certain types of derivative contracts, are variable interest holders in the entity and the variable interest holder, if any, that has both the power to direct the activities that most significantly impact the entity and a variable interest that could potentially be significant to the entity is deemed to be the VIE’s primary beneficiary and is required to consolidate the VIE. Leveraged Leases. In leveraged leasing transactions, Northern Trust acts as lessor of the underlying asset subject to the lease and typically funds 20 - 30% of the asset’s cost via an equity ownership in a trust with the remaining 70 - 80% provided by third-party non-recourse debt holders. In such transactions, the trusts, which are VIEs, are created to provide the lessee use of the property with substantially all of the rights and obligations of ownership. The lessee’s maintenance and operation of the leased property has a direct effect on the fair value of the underlying property, and the lessee also has the ability to increase the benefits it can receive and limit the losses it can suffer by the manner in which it uses the property. As a result, Northern Trust has determined that it is not the primary beneficiary of the leveraged lease trust VIEs given it lacks the power to direct the activities that most significantly impact the economic performance of the leveraged lease trust VIEs. Northern Trust’s maximum exposure to loss as a result of its involvement with leveraged lease trust VIEs is limited to the carrying amounts of its leveraged lease investments. The carrying amounts of these investments, which are included in Loans and Leases on the consolidated balance sheets, were $30.1 million and $42.6 million as of September 30, 2020 and December 31, 2019, respectively. Northern Trust’s funding requirements relative to the leveraged lease trust VIEs are limited to its invested capital. Northern Trust has no other liquidity arrangements or obligations to purchase assets of the leveraged lease trust VIEs that would expose Northern Trust to a loss. Tax Credit Structures. Northern Trust invests in qualified affordable housing projects and community development entities (collectively, community development projects) that are designed to generate a return primarily through the realization of tax credits. The community development projects are formed as limited partnerships and limited liability companies in which Northern Trust invests as a limited partner/investor member through equity contributions. The economic performance of the community development projects, some of which are VIEs, is subject to the performance of their underlying investment and their ability to operate in compliance with the rules and regulations necessary for the qualification of tax credits generated by equity investments. Northern Trust has determined that it is not the primary beneficiary of any community development project VIEs as it lacks the power to direct the activities that most significantly impact the economic performance of the underlying investments or to affect their ability to operate in compliance with the rules and regulations necessary for the qualification of tax credits generated by equity investments. This power is held by the general partners and managing members who exercise full and exclusive control of the operations of the community development project VIEs. Northern Trust’s maximum exposure to loss as a result of its involvement with community development projects is limited to the carrying amounts of its investments, including any undrawn commitments. As of September 30, 2020 and December 31, 2019, the carrying amounts of these investments in community development projects that generate tax credits, included in Other Assets on the consolidated balance sheets, totaled $761.3 million and $749.3 million, respectively, of which $715.5 million and $700.3 million are VIEs as of September 30, 2020 and December 31, 2019, respectively. As of September 30, 2020 and December 31, 2019, liabilities related to unfunded commitments on investments in tax credit community development projects, included in Other Liabilities on the consolidated balance sheets, totaled $300.0 million and $376.2 million, respectively, of which $283.5 million and $354.3 million related to undrawn commitments on VIEs as of September 30, 2020 and December 31, 2019, respectively. Northern Trust’s funding requirements are limited to its invested capital and undrawn commitments for future equity contributions. Northern Trust has no exposure to loss from liquidity arrangements and no obligation to purchase assets of the community development projects. Tax credits and other tax benefits attributable to community development projects totaled $20.7 million and $16.4 million for the three months ended September 30, 2020 and 2019, respectively, and $59.4 million and $49.2 million for the nine months ended September 30, 2020 and 2019, respectively. Investment Funds. Northern Trust acts as asset manager for various funds in which clients of Northern Trust are investors. As an asset manager of funds, Northern Trust earns a competitively priced fee that is based on assets managed and varies with each fund’s investment objective. Based on its analysis, Northern Trust has determined that it is not the primary beneficiary of these VIEs under GAAP. Some of the funds for which Northern Trust acts as asset manager comply or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds and therefore the funds are exempt from the consolidation requirements in ASC 810-10. Northern Trust voluntarily waived $5.4 million and $5.7 million of money market mutual fund fees for the three and nine months ended September 30, 2020, respectively. Northern Trust did not waive any money market mutual fund fees for the three and nine months ended September 30, 2019. Northern Trust does not have any contractual obligations to provide financial support to the funds. Any potential future support of the funds will be at the discretion of Northern Trust after an evaluation of the specific facts and circumstances. Periodically, Northern Trust makes seed capital investments to certain funds. As of September 30, 2020, Northern Trust had $1.7 million of investments valued using net asset value per share and included in Other Assets and had $73.3 million in unfunded commitments related to seed capital investments. As of December 31, 2019, Northern Trust had $112.0 million of investments valued using net asset value per share and included in Other Assets and had no unfunded commitments related to seed capital investments.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Commitments and Contingent Liabilities Commitments, Letters of Credit and Indemnifications. Northern Trust, in the normal course of business, enters into various types of commitments and issues letters of credit to meet the liquidity and credit enhancement needs of its clients. Legally binding commitments to extend credit generally have fixed expiration dates or other termination clauses. Since a significant portion of the commitments are expected to expire without being drawn upon, the total commitment amount does not necessarily represent future loans or liquidity requirements. Legally binding commitments to extend credit totaled $26.4 billion and $24.4 billion as of September 30, 2020 and December 31, 2019, respectively. Standby letters of credit obligate Northern Trust to meet certain financial obligations of its clients, if, under the contractual terms of the agreement, the clients are unable to do so. These instruments are primarily issued to support public and private financial commitments, including commercial paper, bond financing, initial margin requirements on futures exchanges and similar transactions. Northern Trust is obligated to meet the entire financial obligation of these agreements and in certain cases is able to recover the amounts paid through recourse against collateral received or other participants. Standby letters of credit outstanding and financial guarantees were $2.1 billion and $2.4 billion as of September 30, 2020 and December 31, 2019, respectively. Financial guarantees are issued by Northern Trust to guarantee the performance of a client to a third party under certain arrangements. As part of its securities custody activities and at the direction of its clients, Northern Trust lends securities owned by clients to borrowers who are reviewed and approved by the Northern Trust Capital Markets Credit Committee. In connection with these activities, Northern Trust has issued indemnifications to certain clients against certain losses that are a direct result of a borrower’s failure to return securities when due, should the value of such securities exceed the value of the collateral required to be posted. Borrowers are required to collateralize fully securities received with cash or marketable securities. As securities are loaned, collateral is maintained at a minimum of 100% of the fair value of the securities plus accrued interest. The collateral is revalued on a daily basis. The amount of securities loaned as of September 30, 2020 and December 31, 2019 subject to indemnification was $148.3 billion and $138.1 billion, respectively. Because of the credit quality of the borrowers and the requirement to fully collateralize securities borrowed, management believes that the exposure to credit loss from this activity is not significant and no liability was recorded as of September 30, 2020 or December 31, 2019, related to these indemnifications. Legal Proceedings. In the normal course of business, the Corporation and its subsidiaries are routinely defendants in or parties to pending and threatened legal actions, and are subject to regulatory examinations, information-gathering requests, investigations, and proceedings, both formal and informal. In certain legal actions, claims for substantial monetary damages are asserted. In regulatory matters, claims for disgorgement, restitution, penalties and/or other remedial actions or sanctions may be sought. Based on current knowledge, after consultation with legal counsel and after taking into account current accruals, management does not believe that losses, fines or penalties, if any, arising from pending litigation or threatened legal actions or regulatory matters either individually or in the aggregate, after giving effect to applicable reserves and insurance coverage will have a material adverse effect on the consolidated financial position or liquidity of the Corporation, although such matters could have a material adverse effect on the Corporation’s operating results for a particular period. Under GAAP, (i) an event is “probable” if the “future event or events are likely to occur”; (ii) an event is “reasonably possible” if “the chance of the future event or events occurring is more than remote but less than likely”; and (iii) an event is “remote” if “the chance of the future event or events occurring is slight.” The outcome of litigation and regulatory matters is inherently difficult to predict and/or the range of loss often cannot be reasonably estimated, particularly for matters that (i) will be decided by a jury, (ii) are in early stages, (iii) involve uncertainty as to the likelihood of a class being certified or the ultimate size of the class, (iv) are subject to appeals or motions, (v) involve significant factual issues to be resolved, including with respect to the amount of damages, (vi) do not specify the amount of damages sought or (vii) seek very large damages based on novel and complex damage and liability legal theories. Accordingly, the Corporation cannot reasonably estimate the eventual outcome of these pending matters, the timing of their ultimate resolution or what the eventual loss, fines or penalties, if any, related to each pending matter will be. In accordance with applicable accounting guidance, the Corporation records accruals for litigation and regulatory matters when those matters present loss contingencies that are both probable and reasonably estimable. When loss contingencies are not both probable and reasonably estimable, the Corporation does not record accruals. No material accruals have been recorded for pending litigation or threatened legal actions or regulatory matters. For a limited number of matters for which a loss is reasonably possible in future periods, whether in excess of an accrued liability or where there is no accrued liability, the Corporation is able to estimate a range of possible loss. As of September 30, 2020, the Corporation has estimated the range of reasonably possible loss for these matters to be from zero to approximately $15 million in the aggregate. The Corporation’s estimate with respect to the aggregate range of reasonably possible loss is based upon currently available information and is subject to significant judgment and a variety of assumptions and known and unknown uncertainties. The matters underlying the estimated range will change from time to time, and actual results may vary significantly from the current estimate. In certain other pending matters, there may be a range of reasonably possible loss (including reasonably possible loss in excess of amounts accrued) that cannot be reasonably estimated for the reasons described above. Such matters are not included in the estimated range of reasonably possible loss discussed above. In 2015, Northern Trust Fiduciary Services (Guernsey) Limited (NTFS), an indirect subsidiary of the Corporation, was charged by a French investigating magistrate judge with complicity in estate tax fraud in connection with the administration of two trusts for which it serves as trustee. Charges also were brought against a number of other persons and entities related to this matter. In 2017, a French court found no estate tax fraud had occurred and NTFS and all other persons and entities charged were acquitted. The Public Prosecutor’s Office of France appealed the court decision and in June 2018 a French appellate court issued its opinion on the matter, acquitting all persons and entities charged, including NTFS. The Public Prosecutor’s Office of France has appealed the appellate court’s decision to the Cour de Cassation, the highest court in France. As trustee, NTFS provided no tax advice and had no involvement in the preparation or filing of the challenged estate tax filings. Visa Class B Common Shares. Northern Trust, as a member of Visa U.S.A. Inc. (Visa U.S.A.) and in connection with the 2007 restructuring of Visa U.S.A. and its affiliates and the 2008 initial public offering of Visa Inc. (Visa), received certain Visa Class B common shares. The Visa Class B common shares are subject to certain selling restrictions until the final resolution of certain litigation related to interchange fees involving Visa (the covered litigation), at which time the shares are convertible into Visa Class A common shares based on a conversion rate dependent upon the ultimate cost of resolving the covered litigation. On June 28, 2018, and September 27, 2019, Visa deposited an additional $600 million and $300 million, respectively, into an escrow account previously established with respect to the covered litigation. As a result of the additional contributions to the escrow account, the rate at which Visa Class B common shares will convert into Visa Class A common shares was reduced. In September 2018, Visa reached a proposed class settlement agreement covering damage claims but not injunctive relief claims regarding the covered litigation. In December 2019, the district court granted final approval for the proposed class settlement agreement. Certain merchants have opted out of the class settlement and are pursuing claims separately, while other merchants have appealed the approval order granted by the district court. The ultimate resolution of the covered litigation, the timing for removal of the selling restrictions on the Visa Class B common shares and the rate at which such shares will ultimately convert into Visa Class A common shares are uncertain. In June 2016 and 2015, Northern Trust recorded a $123.1 million and $99.9 million net gain on the sale of 1.1 million and 1.0 million of its Visa Class B common shares, respectively. These sales do not affect Northern Trust’s risk related to the impact of the covered litigation on the rate at which such shares will ultimately convert into Visa Class A common shares. Northern Trust continued to hold approximately 4.1 million Visa Class B common shares, which are recorded at their original cost basis of zero, as of September 30, 2020 and December 31, 2019.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments Northern Trust is a party to various derivative financial instruments that are used in the normal course of business to meet the needs of its clients, as part of its trading activity for its own account and as part of its risk management activities. These instruments may include foreign exchange contracts, interest rate contracts, total return swap contracts, and swaps related to the sale of certain Visa Class B common shares. Foreign exchange contracts are agreements to exchange specific amounts of currencies at a future date, at a specified rate of exchange. Foreign exchange contracts are entered into primarily to meet the foreign exchange needs of clients. Foreign exchange contracts are also used for trading and risk management purposes. For risk management purposes, Northern Trust uses foreign exchange contracts to reduce its exposure to changes in foreign exchange rates relating to certain forecasted non-functional-currency-denominated revenue and expenditure transactions, foreign-currency-denominated assets and liabilities, including debt securities, and net investments in non-U.S. affiliates. Interest rate contracts include swap and option contracts. Interest rate swap contracts involve the exchange of fixed and floating rate interest payment obligations without the exchange of the underlying principal amounts. Northern Trust enters into interest rate swap contracts with its clients and also may utilize such contracts to reduce or eliminate the exposure to changes in the cash flows or fair value of hedged assets or liabilities due to changes in interest rates. Interest rate option contracts may include caps, floors, collars and swaptions, and provide for the transfer or reduction of interest rate risk, typically in exchange for a fee. Northern Trust enters into option contracts primarily as a seller of interest rate protection to clients. Northern Trust receives a fee at the outset of the agreement for the assumption of the risk of an unfavorable change in interest rates. This assumed interest rate risk is then mitigated by entering into an offsetting position with an outside counterparty. Northern Trust may also purchase or enter into option contracts for risk management purposes including to reduce the exposure to changes in the cash flows of hedged assets due to changes in interest rates. The following table shows the notional and fair values of all derivative financial instruments as of September 30, 2020 and December 31, 2019. TABLE 75: NOTIONAL AND FAIR VALUES OF DERIVATIVE FINANCIAL INSTRUMENTS SEPTEMBER 30, 2020 DECEMBER 31, 2019 NOTIONAL VALUE FAIR VALUE NOTIONAL VALUE FAIR VALUE (In Millions) ASSET (1) LIABILITY (2) ASSET (1) LIABILITY (2) Derivatives Designated as Hedging under GAAP Interest Rate Contracts Fair Value Hedges $ 5,357.8 $ 10.2 $ 18.9 $ 4,538.2 $ 20.3 $ 20.9 Cash Flow Hedges 150.0 0.3 — 200.0 0.2 0.2 Foreign Exchange Contracts Cash Flow Hedges 5,882.7 14.0 28.9 1,661.5 8.5 11.5 Net Investment Hedges 3,165.3 20.8 83.3 2,873.8 73.7 11.9 Total Derivatives Designated as Hedging under GAAP $ 14,555.8 $ 45.3 $ 131.1 $ 9,273.5 $ 102.7 $ 44.5 Derivatives Not Designated as Hedging under GAAP Non-Designated Risk Management Derivatives Foreign Exchange Contracts $ 79.2 $ 2.0 $ 0.6 $ 176.5 $ 0.9 $ 0.7 Other Financial Derivatives (3) 681.5 — 32.3 640.3 — 33.4 Total Non-Designated Risk Management Derivatives $ 760.7 $ 2.0 $ 32.9 $ 816.8 $ 0.9 $ 34.1 Client-Related and Trading Derivatives Foreign Exchange Contracts $ 255,799.4 $ 2,242.7 $ 2,213.5 $ 291,533.6 $ 3,151.7 $ 3,158.1 Interest Rate Contracts 10,213.8 323.2 123.3 8,976.8 132.4 76.3 Total Client-Related and Trading Derivatives $ 266,013.2 $ 2,565.9 $ 2,336.8 $ 300,510.4 $ 3,284.1 $ 3,234.4 Total Derivatives Not Designated as Hedging under GAAP $ 266,773.9 $ 2,567.9 $ 2,369.7 $ 301,327.2 $ 3,285.0 $ 3,268.5 Total Gross Derivatives $ 281,329.7 $ 2,613.2 $ 2,500.8 $ 310,600.7 $ 3,387.7 $ 3,313.0 Less: Netting (4) 1,408.3 1,603.3 2,338.0 1,618.4 Total Derivative Financial Instruments $ 1,204.9 $ 897.5 $ 1,049.7 $ 1,694.6 (1) Derivative assets are reported in Other Assets on the consolidated balance sheets. (2) Derivative liabilities are reported in Other Liabilities on the consolidated balance sheets. (3) This line includes swaps related to sales of certain Visa Class B common shares. (4) See further detail in Note 21 — Offsetting of Assets and Liabilities. Notional amounts of derivative financial instruments do not represent credit risk, and are not recorded in the consolidated balance sheets. They are used merely to express the volume of this activity. Northern Trust’s credit-related risk of loss is limited to the positive fair value of the derivative instrument, net of any collateral received, which is significantly less than the notional amount. All derivative financial instruments, whether designated as hedges or not, are recorded on the consolidated balance sheets at fair value within Other Assets or Other Liabilities. Northern Trust has elected to net derivative assets and liabilities when legally enforceable master netting arrangements or similar agreements exist between Northern Trust and the counterparty. Hedging Derivative Instruments Designated under GAAP. Northern Trust uses derivative instruments to hedge its exposure to foreign currency, interest rate, and equity price. Certain hedging relationships are formally designated and qualify for hedge accounting under GAAP as fair value, cash flow or net investment hedges. Other derivatives that are entered into for risk management purposes as economic hedges are not formally designated as hedges and changes in fair value are recognized currently in Other Operating Income within the consolidated statements of income (see below section “Derivative Instruments Not Designated as Hedging under GAAP”). In order to qualify for hedge accounting, a formal assessment is performed on a calendar-quarter basis to verify that derivatives used in designated hedging transactions continue to be highly effective in offsetting the changes in fair value or cash flows of the hedged item. If a derivative ceases to be highly effective, matures, is sold or is terminated, or if a hedged forecasted transaction is no longer probable of occurring, hedge accounting is terminated and the derivative is treated as if it were a trading instrument. Fair Value Hedges. Derivatives are designated as fair value hedges to limit Northern Trust’s exposure to changes in the fair value of assets and liabilities due to movements in interest rates. Northern Trust enters into interest rate swaps to hedge changes in fair value of available for sale debt securities and long-term subordinated debt and senior notes. Northern Trust applied the “shortcut” method of accounting, available under GAAP, which assumes there is perfect effectiveness in a hedge, for all of its fair value hedges during the three- and nine- month periods ended September 30, 2020 and 2019. Changes in the fair value of the derivative instrument and changes in the fair value of the hedged asset or liability attributable to the hedged risk are recognized currently in earnings within the same income statement line item. Cash Flow Hedges. Derivatives are also d esignated as cash flow hedges in order to minimize the variability in cash flows of earning assets or forecasted transactions caused by movements in interest or foreign exchange rates. Northern Trust enters into foreign exchange contracts to hedge changes in cash flows due to movements in foreign exchange rates of forecasted foreign- currency-denominated transactions and foreign-currency-denominated debt securities. Northern Trust also enters into interest rate contracts to hedge changes in cash flows due to movements in interest rates of available for sale debt securities. The change in fair value of cash flow hedging derivative instruments are recorded in AOCI and reclassified to earnings when the hedged forecasted transaction impacts earnings within the same income statement line item. There were no material gains or losses reclassified into earnings during the three- and nine- month periods ended September 30, 2020 and 2019, as a result of the discontinuance of forecasted transactions that were no longer probable of occurring. It is estimated that net gains of $0.9 million and net losses of $16.3 million will be reclassified into net income within the next twelve months relating to cash flow hedges of foreign-currency-denominated transactions and cash flow hedges of foreign-currency-denominated debt securities, respectively. It is estimated that net gains of $0.3 million will be reclassified into net income upon the receipt of interest payments on earning assets within the next twelve months relating to cash flow hedges of available for sale debt securities. As of September 30, 2020, 23 months was the maximum length of time over which the exposure to variability in future cash flows of forecasted foreign-currency-denominated transactions was being hedged. The following tables provide fair value and cash flow hedge derivative gains and losses recognized in income during the three- and nine- month periods ended September 30, 2020 and 2019. TABLE 76: LOCATION AND AMOUNT OF FAIR VALUE AND CASH FLOW HEDGE DERIVATIVE GAINS AND LOSSES RECORDED IN INCOME (In Millions) INTEREST INCOME INTEREST EXPENSE OTHER OPERATING INCOME THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 Total amounts on the consolidated statements of income $ 355.4 $ 620.8 $ 26.8 $ 203.1 $ 53.5 $ 45.1 Gains (Losses) on fair value hedges recognized on Interest Rate Contracts Recognized on derivatives 15.1 (14.9) (2.9) 51.4 — — Recognized on hedged items (15.1) 14.9 2.9 (51.4) — — Amounts related to interest settlements on derivatives (14.2) 2.8 (2.5) (6.0) — — Total gains (losses) recognized on fair value hedges $ (14.2) $ 2.8 $ (2.5) $ (6.0) $ — $ — Gains (Losses) on cash flow hedges recognized on Foreign Exchange Contracts Net gains (losses) reclassified from AOCI to net income $ 4.2 $ 2.7 $ — $ — $ 0.3 $ 1.4 Interest Rate Contracts Net gains (losses) reclassified from AOCI to net income 0.2 (0.1) — — — — Total gains (losses) reclassified from AOCI to net income on cash flow hedges $ 4.4 $ 2.6 $ — $ — $ 0.3 $ 1.4 (In Millions) INTEREST INCOME INTEREST EXPENSE OTHER OPERATING INCOME NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 Total amounts on the consolidated statements of income $ 1,290.9 $ 1,923.8 $ 182.1 $ 666.7 $ 144.4 $ 113.0 Gains (Losses) on fair value hedges recognized on Interest Rate Contracts Recognized on derivatives (75.6) (99.0) 152.1 141.6 — — Recognized on hedged items 75.6 99.0 (152.1) (141.6) — — Amounts related to interest settlements on derivatives (11.6) 13.3 6.1 (3.9) — — Total gains (losses) recognized on fair value hedges $ (11.6) $ 13.3 $ 6.1 $ (3.9) $ — $ — Gains (Losses) on cash flow hedges recognized on Foreign Exchange Contracts Net gains (losses) reclassified from AOCI to net income $ 10.8 $ 20.8 $ — $ — $ 0.1 $ 1.1 Interest Rate Contracts Net gains (losses) reclassified from AOCI to net income 0.3 (0.5) — — — — Total gains (losses) reclassified from AOCI to net income on cash flow hedges $ 11.1 $ 20.3 $ — $ — $ 0.1 $ 1.1 The following table provides the impact of fair value hedge accounting on the carrying value of the designated hedged items as of September 30, 2020 and December 31, 2019. TABLE 77: HEDGED ITEMS IN FAIR VALUE HEDGES SEPTEMBER 30, 2020 DECEMBER 31, 2019 (In Millions) CARRYING VALUE OF THE HEDGED ITEMS CUMULATIVE HEDGE ACCOUNTING BASIS ADJUSTMENT (1) CARRYING VALUE OF THE HEDGED ITEMS CUMULATIVE HEDGE ACCOUNTING BASIS ADJUSTMENT (2) Available for Sale Debt Securities (3) $ 2,826.2 $ 63.3 $ 2,981.0 $ 3.3 Senior Notes and Long-Term Subordinated Debt 2,745.0 261.8 1,748.5 126.9 Total $ 5,571.2 $ 325.1 $ 4,729.5 $ 130.2 (1) The cumulative hedge accounting basis adjustment includes $6.7 million related to discontinued hedging relationships of available for sale debt securities as of September 30, 2020. There are no amounts related to discontinued hedging relationships in the cumulative hedge accounting basis adjustment of senior notes and long-term debt as of September 30, 2020. (2) The cumulative hedge accounting basis adjustment includes $1.5 million related to discontinued hedging relationships of available for sale debt securities as of December 31, 2019. There were no amounts related to discontinued hedging relationships in the cumulative hedge accounting basis adjustment of senior notes and long-term debt as of December 31, 2019. (3) Carrying value represents amortized cost. Net Investment Hedges. Certain foreign exchange contracts are designated as net investment hedges to minimize Northern Trust’s exposure to variability in the foreign currency translation of net investments in non-U.S. branches and subsidiaries. Net investment hedge losses of $117.4 million and gains of $107.6 million were recognized in AOCI related to foreign exchange contracts for the three months ended September 30, 2020 and 2019, respectively. Net investment hedge losses of $29.8 million and gains of $144.1 million were recognized in AOCI related to foreign exchange contracts for the nine months ended September 30, 2020 and 2019, respectively. Derivative Instruments Not Designated as Hedging under GAAP. Northern Trust’s derivative instruments that are not designated as hedging under GAAP include derivatives for purposes of client-related and trading activities, as well as other risk management purposes. These activities consist principally of providing foreign exchange services to clients in connection with Northern Trust’s global custody business. However, in the normal course of business, Northern Trust also engages in trading of currencies for its own account. Non-designated risk management derivatives include foreign exchange contracts entered into to manage the foreign currency risk of non-U.S.-dollar-denominated assets and liabilities, the net investment in certain non-U.S. affiliates, commercial loans and forecasted foreign-currency-denominated transactions. Swaps related to sales of certain Visa Class B common shares were entered into pursuant to which Northern Trust retains the risks associated with the ultimate conversion of the Visa Class B common shares into Visa Class A common shares. Total return swaps are entered into to manage the equity price risk associated with certain investments. Changes in the fair value of derivative instruments not designated as hedges under GAAP are recognized currently in income. The following table provides the location and amount of gains and losses recorded in the consolidated statements of income for the three and nine months ended September 30, 2020 and 2019 for derivative instruments not designated as hedges under GAAP. TABLE 78: LOCATION AND AMOUNT OF GAINS AND LOSSES RECORDED IN INCOME FOR DERIVATIVES NOT DESIGNATED AS HEDGING UNDER GAAP (In Millions) DERIVATIVE GAINS (LOSSES) LOCATION RECOGNIZED IN INCOME AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Non-designated risk management derivatives Foreign Exchange Contracts Other Operating Income $ 4.2 $ (1.8) $ 3.8 $ (1.7) Other Financial Derivatives (1) Other Operating Income (5.3) (6.4) (11.0) (17.8) Gains (Losses) from non-designated risk management derivatives $ (1.1) $ (8.2) $ (7.2) $ (19.5) Client-related and trading derivatives Foreign Exchange Contracts Foreign Exchange Trading Income $ 61.6 $ 59.7 $ 221.8 $ 186.4 Interest Rate Contracts Security Commissions and Trading Income 2.3 4.9 18.5 9.2 Gains (Losses) from client-related and trading derivatives $ 63.9 $ 64.6 $ 240.3 $ 195.6 Total gains (losses) from derivatives not designated as hedging under GAAP $ 62.8 $ 56.4 $ 233.1 $ 176.1 (1) This line includes swaps related to the sale of certain Visa Class B common shares and total return swap contracts.

Offsetting of Assets and Liabil

Offsetting of Assets and Liabilities	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Offsetting of Assets and Liabilities	Offsetting of Assets and Liabilities Northern Trust has elected to net derivative assets and liabilities when legally enforceable master netting arrangements or similar agreements exist between Northern Trust and the counterparty. The following table provides information regarding the offsetting of derivative assets and securities purchased under agreements to resell within the consolidated balance sheets as of September 30, 2020 and December 31, 2019. TABLE 79: OFFSETTING OF DERIVATIVE ASSETS AND SECURITIES PURCHASED UNDER AGREEMENTS TO RESELL SEPTEMBER 30, 2020 (In Millions) GROSS RECOGNIZED ASSETS GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (4) Derivative Assets (1) Foreign Exchange Contracts Over the Counter (OTC) $ 1,764.3 $ 1,405.7 $ 358.6 $ 29.7 $ 328.9 Interest Rate Swaps OTC 333.7 2.6 331.1 — 331.1 Total Derivatives Subject to a Master Netting Arrangement 2,098.0 1,408.3 689.7 29.7 660.0 Total Derivatives Not Subject to a Master Netting Arrangement 515.2 — 515.2 0.9 514.3 Total Derivatives 2,613.2 1,408.3 1,204.9 30.6 1,174.3 Securities Purchased under Agreements to Resell (3) $ 1,533.4 $ — $ 1,533.4 $ 1,533.4 $ — DECEMBER 31, 2019 (In Millions) GROSS RECOGNIZED ASSETS GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (4) Derivative Assets (1) Foreign Exchange Contracts OTC $ 2,691.1 $ 2,334.1 $ 357.0 $ 16.5 $ 340.5 Interest Rate Swaps OTC 151.9 3.9 148.0 — 148.0 Interest Rate Swaps Exchange Cleared 1.0 — 1.0 — 1.0 Total Derivatives Subject to a Master Netting Arrangement 2,844.0 2,338.0 506.0 16.5 489.5 Total Derivatives Not Subject to a Master Netting Arrangement 543.7 — 543.7 0.3 543.4 Total Derivatives 3,387.7 2,338.0 1,049.7 16.8 1,032.9 Securities Purchased under Agreements to Resell (3) $ 707.8 $ — $ 707.8 $ 707.8 $ — (1) Derivative assets are reported in Other Assets on the consolidated balance sheets. Other Assets (excluding derivative assets) totaled $7.3 billion and $7.4 billion as of September 30, 2020 and December 31, 2019, respectively. (2) Including cash collateral received from counterparties. (3) Securities purchased under agreements to resell are reported in Federal Funds Sold and Securities Purchased under Agreements to Resell on the consolidated balance sheets. There were no Federal Funds Sold as of September 30, 2020 and $5.0 million of Federal Funds Sold as of December 31, 2019. (4) Northern Trust did not possess any cash collateral that was not offset in the consolidated balance sheets that could have been used to offset the net amounts presented in the consolidated balance sheets as of September 30, 2020 and December 31, 2019. The following table provides information regarding the offsetting of derivative liabilities and securities sold under agreements to repurchase within the consolidated balance sheets as of September 30, 2020 and December 31, 2019. TABLE 80: OFFSETTING OF DERIVATIVE LIABILITIES AND SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE SEPTEMBER 30, 2020 (In Millions) GROSS RECOGNIZED LIABILITIES GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (3) Derivative Liabilities (1) Foreign Exchange Contracts OTC $ 1,969.2 $ 1,493.6 $ 475.6 $ — $ 475.6 Interest Rate Swaps OTC 142.3 109.7 32.6 — 32.6 Other Financial Derivatives 32.3 — 32.3 — 32.3 Total Derivatives Subject to a Master Netting Arrangement 2,143.8 1,603.3 540.5 — 540.5 Total Derivatives Not Subject to a Master Netting Arrangement 357.0 — 357.0 — 357.0 Total Derivatives 2,500.8 1,603.3 897.5 — 897.5 Securities Sold under Agreements to Repurchase $ 269.8 $ — $ 269.8 $ 269.8 $ — DECEMBER 31, 2019 (In Millions) GROSS RECOGNIZED LIABILITIES GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (3) Derivative Liabilities (1) Foreign Exchange Contracts OTC $ 2,181.6 $ 1,548.6 $ 633.0 $ 0.1 $ 632.9 Interest Rate Swaps OTC 96.7 57.3 39.4 — 39.4 Interest Rate Swaps Exchange Cleared 0.7 — 0.7 — 0.7 Other Financial Derivatives 33.4 12.5 20.9 — 20.9 Total Derivatives Subject to a Master Netting Arrangement 2,312.4 1,618.4 694.0 0.1 693.9 Total Derivatives Not Subject to a Master Netting Arrangement 1,000.6 — 1,000.6 — 1,000.6 Total Derivatives 3,313.0 1,618.4 1,694.6 0.1 1,694.5 Securities Sold under Agreements to Repurchase $ 489.7 $ — $ 489.7 $ 489.7 $ — (1) Derivative liabilities are reported in Other Liabilities on the consolidated balance sheets. Other Liabilities (excluding derivative liabilities) totaled $3.6 billion and $3.1 billion as of September 30, 2020 and December 31, 2019, respectively. (2) Including cash collateral deposited with counterparties. (3) Northern Trust did not place any cash collateral with counterparties that was not offset in the consolidated balance sheets that could have been used to offset the net amounts presented in the consolidated balance sheets as of September 30, 2020 and December 31, 2019. All of Northern Trust’s securities sold under agreements to repurchase (repurchase agreements) and securities purchased under agreements to resell (reverse repurchase agreements) involve the transfer of financial assets in exchange for cash subject to a right and obligation to repurchase those assets for an agreed upon amount. In the event of a repurchase failure, the cash or financial assets are available for offset. All of Northern Trust’s repurchase agreements and reverse repurchase agreements are subject to a master netting arrangement, which sets forth the rights and obligations for repurchase and offset. Under the master netting arrangement, Northern Trust is entitled to offset receivables from and collateral placed with a single counterparty against obligations owed to that counterparty. In addition, collateral held by Northern Trust can be offset against receivables from that counterparty. However, Northern Trust’s repurchase agreements and reverse repurchase agreements do not meet the requirements to net under GAAP. Derivative asset and liability positions with a single counterparty can be offset against each other in cases where legally enforceable master netting arrangements or similar agreements exist. Derivative assets and liabilities can be further offset by cash collateral received from, and deposited with, the transacting counterparty. The basis for this view is that, upon termination of transactions subject to a master netting arrangement or similar agreement, the individual derivative receivables do not represent resources to which general creditors have rights and individual derivative payables do not represent claims that are equivalent to the claims of general creditors. Credit risk associated with derivative instruments relates to the failure of the counterparty and the failure of Northern Trust to pay based on the contractual terms of the agreement, and is generally limited to the unrealized fair value gains and losses on these instruments, net of any collateral received or deposited. The amount of credit risk will increase or decrease during the lives of the instruments as interest rates, foreign exchange rates, or equity prices fluctuate. Northern Trust’s risk is controlled by limiting such activity to an approved list of counterparties and by subjecting such activity to the same credit and quality controls as are followed in lending and investment activities. Credit Support Annexes and other similar agreements are currently in place with a number of Northern Trust’s counterparties which mitigate the aforementioned credit risk associated with derivative activity conducted with those counterparties by requiring that significant net unrealized fair value gains be supported by collateral placed with Northern Trust. Additional cash collateral received from and deposited with derivative counterparties totaling $281.0 million and $280.8 million, respectively, as of September 30, 2020, and $196.3 million and $2.0 million, respectively, as of December 31, 2019, was not offset against derivative assets and liabilities in the consolidated balance sheets as the amounts exceeded the net derivative positions with those counterparties. Certain master netting arrangements Northern Trust enters into with derivative counterparties contain credit-risk-related contingent features in which the counterparty has the option to declare Northern Trust in default and accelerate cash settlement of net derivative liabilities with the counterparty in the event Northern Trust’s credit rating falls below specified levels. The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a liability position was $565.5 million and $766.2 million at September 30, 2020 and December 31, 2019, respectively. Cash collateral amounts deposited with derivative counterparties on those dates included $184.4 million and $327.1 million, respectively, posted against these liabilities, resulting in a net maximum amount of termination payments that could have been required at September 30, 2020 and December 31, 2019, of $381.1 million and $439.1 million, respectively. Accelerated settlement of these liabilities would not have a material effect on the consolidated financial position or liquidity of Northern Trust.

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	On January 1, 2020, Northern Trust adopted Accounting Standards Update (ASU) No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (ASU 2016-13). ASU 2016-13 significantly changed the way impairment of financial instruments is recognized by requiring immediate recognition of estimated credit losses expected to occur over the remaining life of financial instruments. The main provisions of ASU 2016-13 include (1) replacing the “incurred loss” approach under current GAAP with an “expected loss” model for instruments measured at amortized cost, (2) requiring entities to record an allowance for available for sale debt securities rather than reduce the carrying amount of the investments, as is required by the other-than-temporary-impairment model under legacy GAAP, and (3) a simplified accounting model for purchased credit-impaired debt securities and loans. Upon adoption of ASU 2016-13 On January 1, 2020, Northern Trust adopted ASU No. 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment” (ASU 2017-04). ASU 2017-04 amends the subsequent measurement of goodwill whereby Step 2 from the goodwill impairment test is eliminated. As a result, the goodwill impairment test is performed by comparing the fair value of a reporting unit to its carrying value and an impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value, not to exceed the total amount of goodwill allocated to that reporting unit. Upon adoption of ASU 2017-04, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On January 1, 2020, Northern Trust adopted ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement” (ASU 2018-13). The primary objective of ASU 2018-13 is to improve the effectiveness of disclosures in the notes to financial statements. Upon adoption of ASU 2018-13, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On January 1, 2020, Northern Trust adopted ASU No. 2018-15, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force)” (ASU 2018-15). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). Upon adoption of ASU 2018-15, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On January 1, 2020, Northern Trust adopted ASU No. 2018-17, “Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities” (ASU 2018-17). ASU 2018-17 requires that indirect interests held through related parties in common control arrangements should be considered on a proportional basis (rather than as the equivalent of a direct interest in its entirety) for determining whether fees paid to decision makers and service providers are variable interests. Upon adoption of ASU 2018-17, there was no significant impact to Northern Trust’s consolidated financial condition or results of operations. On April 1, 2020, Northern Trust adopted ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (ASU 2020-04). The global transition toward alternative reference rates and away from referencing the London Interbank Offered Rate (LIBOR) and other interbank offered rates (Reference Rate Reform) is expected to have a significant impact on the volume of contract modifications, hedge accounting, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of Reference Rate Reform. ASU 2020-04 provides temporary optional expedients and exceptions for applying GAAP to contract modifications, hedging relationships, and other transactions affected by Reference Rate Reform if certain criteria are met. The main provisions of ASU 2020-04 provide the following optional expedients: (1) simplification of the accounting evaluations under current GAAP for contract modifications, including loan, debt, lease and other contracts with potential embedded derivatives, if qualifying criteria are met (2) preservation of hedging relationships without dedesignation upon certain changes to the critical terms of an existing hedging relationship due to Reference Rate Reform and other optional hedge accounting relief provisions and (3) a one-time election to sell or transfer, or both sell and transfer, debt securities classified as held to maturity that reference a rate affected by Reference Rate Reform and are classified as held to maturity before January 1, 2020. The optional expedients in ASU 2020-04 for contract modifications and hedging relationships are applied prospectively, while the one-time election to sell or transfer, or both sell and transfer debt securities classified as held to maturity may be made at any time after March 12, 2020. The optional expedients and exceptions provided by ASU 2020-04 do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, except for hedging relationships existing as of December 31, 2022 for which an entity has elected certain optional expedients and which are retained through the end of the hedging relationship.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement Inputs and Valuation Techniques	The following table presents the fair values of Northern Trust’s Level 3 liabilities as of September 30, 2020 and December 31, 2019, as well as the valuation techniques, significant unobservable inputs, and quantitative information used to develop significant unobservable inputs for such liabilities as of such dates. TABLE 36: LEVEL 3 SIGNIFICANT UNOBSERVABLE INPUTS SEPTEMBER 30, 2020 FINANCIAL INSTRUMENT FAIR VALUE VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES (1) Swaps Related to Sale of Certain Visa Class B Common Shares $32.3 million Discounted Cash Flow Conversion Rate 1.62x 1.62x Visa Class A Appreciation 8.70% 8.70% Expected Duration 12 - 33 months 20 months (1) Weighted average of expected duration based on scenario probability. DECEMBER 31, 2019 FINANCIAL INSTRUMENT FAIR VALUE VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES (1) Swaps Related to Sale of Certain Visa Class B Common Shares $33.4 million Discounted Cash Flow Conversion Rate 1.62x 1.62x Visa Class A Appreciation 8.54% 8.54% Expected Duration 12 - 36 months 22 months (1) Weighted average of expected duration based on scenario probability. The following table presents the fair values of Northern Trust’s Level 3 assets that were measured at fair value on a nonrecurring basis as of September 30, 2020 and December 31, 2019, as well as the valuation technique, significant unobservable inputs and quantitative information used to develop the significant unobservable inputs for such assets as of such dates. TABLE 39: LEVEL 3 NONRECURRING BASIS SIGNIFICANT UNOBSERVABLE INPUTS SEPTEMBER 30, 2020 FINANCIAL INSTRUMENT FAIR VALUE (1) VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES Loans $21.2 million Market Approach Discount factor applied to real estate collateral-based loans to reflect realizable value 15.0% - 20.0% 15.2% (1) Includes real estate collateral-based loans and other collateral-based loans. DECEMBER 31, 2019 FINANCIAL INSTRUMENT FAIR VALUE (1) VALUATION TECHNIQUE UNOBSERVABLE INPUTS INPUT VALUES WEIGHTED-AVERAGE INPUT VALUES Loans $8.0 million Market Approach Discount factor applied to real estate collateral-based loans to reflect realizable value 15.0 % - 20.0% 15.3% (1) Includes real estate collateral-based loans and other collateral-based loans.
Recurring Basis Hierarchy Leveling	The following table presents assets and liabilities measured at fair value on a recurring basis as of September 30, 2020 and December 31, 2019, segregated by fair value hierarchy level. TABLE 37: RECURRING BASIS HIERARCHY LEVELING SEPTEMBER 30, 2020 (In Millions) LEVEL 1 LEVEL 2 LEVEL 3 NETTING ASSETS/LIABILITIES AT FAIR VALUE Debt Securities Available for Sale U.S. Government $ 4,165.2 $ — $ — $ — $ 4,165.2 Obligations of States and Political Subdivisions — 2,600.5 — — 2,600.5 Government Sponsored Agency — 24,568.8 — — 24,568.8 Non-U.S. Government — 937.6 — — 937.6 Corporate Debt — 2,627.4 — — 2,627.4 Covered Bonds — 516.8 — — 516.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds — 2,552.8 — — 2,552.8 Other Asset-Backed — 3,559.4 — — 3,559.4 Commercial Mortgage-Backed — 1,015.2 — — 1,015.2 Other — 7.3 — — 7.3 Total Available for Sale 4,165.2 38,385.8 — — 42,551.0 Trading Account 0.3 0.3 — — 0.6 Total Available for Sale and Trading Debt Securities 4,165.5 38,386.1 — — 42,551.6 Other Assets Derivative Assets Foreign Exchange Contracts — 2,279.5 — (1,405.7) 873.8 Interest Rate Contracts — 333.7 — (2.6) 331.1 Total Derivative Assets — 2,613.2 — (1,408.3) 1,204.9 Other Liabilities Derivative Liabilities Foreign Exchange Contracts — 2,326.3 — (1,493.6) 832.7 Interest Rate Contracts — 142.2 — (109.7) 32.5 Other Financial Derivatives (1) — — 32.3 — 32.3 Total Derivative Liabilities $ — $ 2,468.5 $ 32.3 $ (1,603.3) $ 897.5 Note: Northern Trust has elected to net derivative assets and liabilities when legally enforceable master netting arrangements or similar agreements exist between Northern Trust and the counterparty. As of September 30, 2020, derivative assets and liabilities shown above also include reductions of $212.7 million and $407.7 million, respectively, as a result of cash collateral received from and deposited with derivative counterparties. (1) This line consists of swaps related to the sale of certain Visa Class B common shares. DECEMBER 31, 2019 (In Millions) LEVEL 1 LEVEL 2 LEVEL 3 NETTING ASSETS/LIABILITIES AT FAIR VALUE Debt Securities Available for Sale U.S. Government $ 4,549.1 $ — $ — $ — $ 4,549.1 Obligations of States and Political Subdivisions — 1,615.3 — — 1,615.3 Government Sponsored Agency — 23,271.2 — — 23,271.2 Non-U.S. Government — 3.3 — — 3.3 Corporate Debt — 2,402.7 — — 2,402.7 Covered Bonds — 769.9 — — 769.9 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds — 2,127.6 — — 2,127.6 Other Asset-Backed — 3,330.5 — — 3,330.5 Commercial Mortgage-Backed — 797.7 — — 797.7 Other — 9.0 — — 9.0 Total Available for Sale 4,549.1 34,327.2 — — 38,876.3 Trading Account — 0.3 — — 0.3 Total Available for Sale and Trading Debt Securities 4,549.1 34,327.5 — — 38,876.6 Other Assets Derivative Assets Foreign Exchange Contracts — 3,234.8 — (2,334.1) 900.7 Interest Rate Contracts — 152.9 — (3.9) 149.0 Total Derivative Assets — 3,387.7 — (2,338.0) 1,049.7 Other Liabilities Derivative Liabilities Foreign Exchange Contracts — 3,182.2 — (1,548.6) 1,633.6 Interest Rate Contracts — 97.4 — (57.3) 40.1 Other Financial Derivatives (1) — — 33.4 (12.5) 20.9 Total Derivative Liabilities $ — $ 3,279.6 $ 33.4 $ (1,618.4) $ 1,694.6 Note: Northern Trust has elected to net derivative assets and liabilities when legally enforceable master netting arrangements or similar agreements exist between Northern Trust and the counterparty. As of December 31, 2019, derivative assets and liabilities shown above also include reductions of $1,136.8 million and $417.2 million, respectively, as a result of cash collateral received from and deposited with derivative counterparties.
Changes in Level 3 Liabilities	The following table presents the changes in Level 3 liabilities for the three and nine months ended September 30, 2020 and 2019. TABLE 38: CHANGES IN LEVEL 3 LIABILITIES (In Millions) SWAPS RELATED TO SALE OF CERTAIN VISA CLASS B COMMON SHARES THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 Fair Value at July 1 $ 31.3 $ 34.7 Total (Gains) Losses: Included in Earnings (1) 5.3 6.7 Purchases, Issues, Sales, and Settlements Settlements (4.3) (3.7) Fair Value at September 30 $ 32.3 $ 37.7 (1) (Gains) losses are recorded in Other Operating Income on the consolidated statements of income. NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 Fair Value at January 1 $ 33.4 $ 32.8 Total (Gains) Losses: Included in Earnings (1) 11.0 14.9 Purchases, Issues, Sales, and Settlements Settlements (12.1) (10.0) Fair Value at September 30 $ 32.3 $ 37.7 (1) (Gains) losses are recorded in Other Operating Income on the consolidated statements of income.
Fair Value of Financial Instruments	The following table summarizes the fair values of all financial instruments. TABLE 40: FAIR VALUE OF FINANCIAL INSTRUMENTS SEPTEMBER 30, 2020 FAIR VALUE (In Millions) BOOK VALUE TOTAL FAIR VALUE LEVEL 1 LEVEL 2 LEVEL 3 ASSETS Cash and Due from Banks $ 4,737.5 $ 4,737.5 $ 4,737.5 $ — $ — Federal Reserve and Other Central Bank Deposits 39,244.6 39,244.6 — 39,244.6 — Interest-Bearing Deposits with Banks 2,754.4 2,754.4 — 2,754.4 — Federal Funds Sold and Securities Purchased under Agreements to Resell 1,533.4 1,533.4 — 1,533.4 — Debt Securities Available for Sale (1) 42,551.0 42,551.0 4,165.2 38,385.8 — Held to Maturity 16,754.0 16,746.5 99.0 16,647.5 — Trading Account 0.6 0.6 0.3 0.3 — Loans (excluding Leases) Held for Investment 32,521.2 33,001.4 — — 33,001.4 Client Security Settlement Receivables 2,296.8 2,296.8 — 2,296.8 — Other Assets Federal Reserve and Federal Home Loan Bank Stock 239.7 239.7 — 239.7 — Community Development Investments 761.3 761.3 — 761.3 — Employee Benefit and Deferred Compensation 214.6 230.0 143.6 86.4 — LIABILITIES Deposits Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing $ 59,756.8 $ 59,756.8 $ 59,756.8 $ — $ — Savings Certificates and Other Time 1,486.7 1,496.5 — 1,496.5 — Non U.S. Offices Interest-Bearing 61,345.6 61,345.6 — 61,345.6 — Federal Funds Purchased 2,203.7 2,203.7 — 2,203.7 — Securities Sold Under Agreements to Repurchase 269.8 269.8 — 269.8 — Other Borrowings 5,771.7 5,772.9 — 5,772.9 — Senior Notes 3,655.6 3,731.0 — 3,731.0 — Long-Term Debt Subordinated Debt 1,196.0 1,250.0 — 1,250.0 — Floating Rate Capital Debt 277.7 255.6 — 255.6 — Other Liabilities Standby Letters of Credit 23.9 23.9 — — 23.9 Loan Commitments 55.7 55.7 — — 55.7 Derivative Instruments Asset/Liability Management Foreign Exchange Contracts Assets $ 36.8 $ 36.8 $ — $ 36.8 $ — Liabilities 112.8 112.8 — 112.8 — Interest Rate Contracts Assets 10.5 10.5 — 10.5 — Liabilities 18.9 18.9 — 18.9 — Other Financial Derivatives Liabilities (2) 32.3 32.3 — — 32.3 Client-Related and Trading Foreign Exchange Contracts Assets 2,242.7 2,242.7 — 2,242.7 — Liabilities 2,213.5 2,213.5 — 2,213.5 — Interest Rate Contracts Assets 323.2 323.2 — 323.2 — Liabilities 123.3 123.3 — 123.3 — (1) Refer to the table located on page 46 for the disaggregation of available for sale debt securities. (2) This line consists of swaps related to the sale of certain Visa Class B common shares. DECEMBER 31, 2019 FAIR VALUE (In Millions) BOOK VALUE TOTAL FAIR VALUE LEVEL 1 LEVEL 2 LEVEL 3 ASSETS Cash and Due from Banks $ 4,459.2 $ 4,459.2 $ 4,459.2 $ — $ — Federal Reserve and Other Central Bank Deposits 33,886.0 33,886.0 — 33,886.0 — Interest-Bearing Deposits with Banks 4,877.1 4,877.1 — 4,877.1 — Federal Funds Sold and Securities Purchased under Agreements to Resell 712.8 712.8 — 712.8 — Debt Securities Available for Sale (1) 38,876.3 38,876.3 4,549.1 34,327.2 — Held to Maturity 12,284.5 12,249.3 138.8 12,110.5 — Trading Account 0.3 0.3 — 0.3 — Loans (excluding Leases) Held for Investment 31,239.5 31,517.8 — — 31,517.8 Client Security Settlement Receivables 845.7 845.7 — 845.7 — Other Assets Federal Reserve and Federal Home Loan Bank Stock 301.2 301.2 — 301.2 — Community Development Investments 749.3 749.3 — 749.3 — Employee Benefit and Deferred Compensation 199.5 207.6 131.0 76.6 — LIABILITIES Deposits Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing $ 47,733.6 $ 47,733.6 $ 47,733.6 $ — $ — Savings Certificates and Other Time 986.7 994.2 — 994.2 — Non U.S. Offices Interest-Bearing 60,400.3 60,400.3 — 60,400.3 — Federal Funds Purchased 552.9 552.9 — 552.9 — Securities Sold Under Agreements to Repurchase 489.7 489.7 — 489.7 — Other Borrowings 6,744.8 6,745.9 — 6,745.9 — Senior Notes 2,573.0 2,593.0 — 2,593.0 — Long-Term Debt Subordinated Debt 1,148.1 1,169.5 — 1,169.5 — Floating Rate Capital Debt 277.7 262.1 — 262.1 — Other Liabilities Standby Letters of Credit 25.5 25.5 — — 25.5 Loan Commitments 32.3 32.3 — — 32.3 Derivative Instruments Asset/Liability Management Foreign Exchange Contracts Assets $ 83.1 $ 83.1 $ — $ 83.1 $ — Liabilities 24.1 24.1 — 24.1 — Interest Rate Contracts Assets 20.5 20.5 — 20.5 — Liabilities 21.1 21.1 — 21.1 — Other Financial Derivatives Liabilities (2) 33.4 33.4 — — 33.4 Client-Related and Trading Foreign Exchange Contracts Assets 3,151.7 3,151.7 — 3,151.7 — Liabilities 3,158.1 3,158.1 — 3,158.1 — Interest Rate Contracts Assets 132.4 132.4 — 132.4 — Liabilities 76.3 76.3 — 76.3 — (1) Refer to the table located on page 47 for the disaggregation of available for sale debt securities. (2) This line consists of swaps related to the sale of certain Visa Class B common shares.

Securities (Tables)

Securities (Tables)	9 Months Ended
	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Reconciliation of Amortized Cost to Fair Value of Securities Available for Sale	The following tables provide the amortized cost and fair values at September 30, 2020 and December 31, 2019, and remaining maturities of debt securities available for sale at September 30, 2020. TABLE 41: RECONCILIATION OF AMORTIZED COST TO FAIR VALUE OF DEBT SECURITIES AVAILABLE FOR SALE SEPTEMBER 30, 2020 (In Millions) AMORTIZED COST GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR VALUE U.S. Government $ 4,083.9 $ 81.3 $ — $ 4,165.2 Obligations of States and Political Subdivisions 2,465.2 136.3 1.0 2,600.5 Government Sponsored Agency 24,162.6 427.4 21.2 24,568.8 Non-U.S. Government 936.8 0.9 0.1 937.6 Corporate Debt 2,548.7 80.9 2.2 2,627.4 Covered Bonds 508.5 8.3 — 516.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 2,486.4 66.7 0.3 2,552.8 Other Asset-Backed 3,522.3 46.6 9.5 3,559.4 Commercial Mortgage-Backed 937.5 78.4 0.7 1,015.2 Other 7.3 — — 7.3 Total $ 41,659.2 $ 926.8 $ 35.0 $ 42,551.0 DECEMBER 31, 2019 (In Millions) AMORTIZED COST GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR VALUE U.S. Government $ 4,527.5 $ 26.7 $ 5.1 $ 4,549.1 Obligations of States and Political Subdivisions 1,604.0 24.6 13.3 1,615.3 Government Sponsored Agency 23,247.5 101.8 78.1 23,271.2 Non-U.S. Government 3.3 — — 3.3 Corporate Debt 2,378.9 27.8 4.0 2,402.7 Covered Bonds 766.3 4.4 0.8 769.9 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 2,091.3 37.4 1.1 2,127.6 Other Asset-Backed 3,324.5 11.3 5.3 3,330.5 Commercial Mortgage-Backed 769.9 28.7 0.9 797.7 Other 9.0 — — 9.0 Total $ 38,722.2 $ 262.7 $ 108.6 $ 38,876.3
Remaining Maturity of Securities Available for Sale and Held to Maturity	TABLE 42: REMAINING MATURITY OF DEBT SECURITIES AVAILABLE FOR SALE SEPTEMBER 30, 2020 ONE YEAR OR LESS ONE TO FIVE YEARS FIVE TO TEN YEARS OVER TEN YEARS TOTAL (In Millions) AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE AMORTIZED COST FAIR VALUE U.S. Government $ 1,802.3 $ 1,805.4 $ 1,834.8 $ 1,876.1 $ 446.8 $ 483.7 $ — $ — $ 4,083.9 $ 4,165.2 Obligations of States and Political Subdivisions 16.4 16.4 210.9 222.8 2,187.7 2,311.0 50.2 50.3 2,465.2 2,600.5 Government Sponsored Agency 6,077.0 6,160.5 9,520.9 9,669.4 6,111.1 6,224.2 2,453.6 2,514.7 24,162.6 24,568.8 Non-U.S. Government 737.9 738.2 40.7 40.6 158.2 158.8 — — 936.8 937.6 Corporate Debt 547.1 552.9 2,001.6 2,074.5 — — — — 2,548.7 2,627.4 Covered Bonds 24.4 24.5 484.1 492.3 — — — — 508.5 516.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 334.9 335.1 2,046.0 2,111.8 105.5 105.9 — — 2,486.4 2,552.8 Other Asset-Backed 412.4 419.0 2,658.0 2,690.0 356.0 354.5 95.9 95.9 3,522.3 3,559.4 Commercial Mortgage-Backed 16.6 16.7 336.2 360.3 567.1 620.6 17.6 17.6 937.5 1,015.2 Other 7.3 7.3 — — — — — — 7.3 7.3 Total $ 9,976.3 $ 10,076.0 $ 19,133.2 $ 19,537.8 $ 9,932.4 $ 10,258.7 $ 2,617.3 $ 2,678.5 $ 41,659.2 $ 42,551.0 Note: Mortgage-backed and asset-backed securities are included in the above table taking into account anticipated future prepayments. TABLE 45: REMAINING MATURITY OF DEBT SECURITIES HELD TO MATURITY SEPTEMBER 30, 2020 ONE YEAR OR LESS ONE TO FIVE YEARS FIVE TO TEN YEARS OVER TEN YEARS TOTAL (In Millions) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value U.S. Government $ 99.0 $ 99.0 $ — $ — $ — $ — $ — $ — $ 99.0 $ 99.0 Obligations of States and Political Subdivisions 1.6 1.6 1.0 1.1 — — — — 2.6 2.7 Government Sponsored Agency 0.5 0.6 1.5 1.6 0.9 1.0 0.5 0.5 3.4 3.7 Non-U.S. Government 7,291.5 7,293.2 260.3 266.5 — — — — 7,551.8 7,559.7 Corporate Debt 125.0 125.2 405.3 410.6 — — — — 530.3 535.8 Covered Bonds 1,228.1 1,233.1 2,133.6 2,153.0 — — — — 3,361.7 3,386.1 Certificates of Deposit 726.3 726.3 — — — — — — 726.3 726.3 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 832.7 837.1 2,325.2 2,362.7 232.6 233.2 — — 3,390.5 3,433.0 Other Asset-Backed 190.1 190.1 435.4 435.8 20.3 20.4 — — 645.8 646.3 Other 21.3 20.8 251.4 228.1 58.9 49.4 111.0 55.6 442.6 353.9 Total $ 10,516.1 $ 10,527.0 $ 5,813.7 $ 5,859.4 $ 312.7 $ 304.0 $ 111.5 $ 56.1 $ 16,754.0 $ 16,746.5
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	The following table provides information regarding debt securities available for sale with no credit losses reported that had been in a continuous unrealized loss position for less than twelve months and for twelve months or longer as of September 30, 2020 and December 31, 2019. TABLE 43: DEBT SECURITIES AVAILABLE FOR SALE IN UNREALIZED LOSS POSITION WITH NO CREDIT LOSSES REPORTED AS OF SEPTEMBER 30, 2020 LESS THAN 12 MONTHS 12 MONTHS OR LONGER TOTAL (In Millions) FAIR UNREALIZED FAIR UNREALIZED FAIR UNREALIZED Obligations of States and Political Subdivisions $ 230.4 $ 1.0 $ — $ — $ 230.4 $ 1.0 Government Sponsored Agency 2,578.6 6.8 2,862.3 14.4 5,440.9 21.2 Non-U.S. Government 26.5 0.1 — — 26.5 0.1 Corporate Debt 69.1 1.0 76.1 1.2 145.2 2.2 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 146.3 0.2 158.7 0.1 305.0 0.3 Other Asset-Backed 631.2 1.0 846.3 8.5 1,477.5 9.5 Commercial Mortgage-Backed 76.3 0.7 — — 76.3 0.7 Total $ 3,758.4 $ 10.8 $ 3,943.4 $ 24.2 $ 7,701.8 $ 35.0 AS OF DECEMBER 31, 2019 LESS THAN 12 MONTHS 12 MONTHS OR LONGER TOTAL (In Millions) FAIR UNREALIZED FAIR UNREALIZED FAIR UNREALIZED U.S. Government $ 252.2 $ 2.8 $ 899.7 $ 2.3 $ 1,151.9 $ 5.1 Obligations of States and Political Subdivisions 902.4 13.3 — — 902.4 13.3 Government Sponsored Agency 5,405.0 35.6 7,818.4 42.5 13,223.4 78.1 Corporate Debt 279.3 1.1 492.7 2.9 772.0 4.0 Covered Bonds 138.7 0.7 25.0 0.1 163.7 0.8 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 217.5 1.0 155.2 0.1 372.7 1.1 Other Asset-Backed 592.4 1.8 1,164.9 3.5 1,757.3 5.3 Commercial Mortgage-Backed 62.8 0.7 59.3 0.2 122.1 0.9 Total $ 7,850.3 $ 57.0 $ 10,615.2 $ 51.6 $ 18,465.5 $ 108.6
Debt Securities, Held-to-maturity	The following tables provide the amortized cost and fair values at September 30, 2020 and December 31, 2019, and remaining maturities of debt securities held to maturity at September 30, 2020. TABLE 44: RECONCILIATION OF AMORTIZED COST TO FAIR VALUE OF DEBT SECURITIES HELD TO MATURITY SEPTEMBER 30, 2020 (In Millions) AMORTIZED GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR U.S Government $ 99.0 $ — $ — $ 99.0 Obligations of States and Political Subdivisions 2.6 0.1 — 2.7 Government Sponsored Agency 3.4 0.3 — 3.7 Non-U.S. Government 7,551.8 8.1 0.2 7,559.7 Corporate Debt 530.3 5.5 — 535.8 Covered Bonds 3,361.7 25.4 1.0 3,386.1 Certificates of Deposit 726.3 — — 726.3 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 3,390.5 42.8 0.3 3,433.0 Other Asset-Backed 645.8 0.7 0.2 646.3 Other 442.6 — 88.7 353.9 Total $ 16,754.0 $ 82.9 $ 90.4 $ 16,746.5 DECEMBER 31, 2019 (In Millions) AMORTIZED GROSS UNREALIZED GAINS GROSS UNREALIZED LOSSES FAIR U.S. Government $ 138.8 $ — $ — $ 138.8 Obligations of States and Political Subdivisions 10.1 0.2 — 10.3 Government Sponsored Agency 4.1 0.2 — 4.3 Non-U.S. Government 4,076.0 5.3 2.5 4,078.8 Corporate Debt 405.1 1.4 0.3 406.2 Covered Bonds 3,006.7 16.1 2.4 3,020.4 Certificates of Deposit 262.9 — — 262.9 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 3,285.4 21.7 2.1 3,305.0 Other Asset-Backed 804.3 0.7 0.3 804.7 Other 291.1 0.1 73.3 217.9 Total $ 12,284.5 $ 45.7 $ 80.9 $ 12,249.3
Debt Securities, Held-to-maturity, Credit Quality Indicator	The following table provides the amortized cost of debt securities held to maturity by credit rating. TABLE 46: AMORTIZED COST OF DEBT SECURITIES HELD TO MATURITY BY CREDIT RATING AS OF SEPTEMBER 30, 2020 (In Millions) AAA AA A BBB NOT RATED TOTAL U.S. Government $ 99.0 $ — $ — $ — $ — $ 99.0 Obligations of States and Political Subdivisions — 0.6 0.7 1.3 — 2.6 Government Sponsored Agency 3.4 — — — — 3.4 Non-U.S. Government 335.6 1,269.7 5,899.8 46.7 — 7,551.8 Corporate Debt 3.6 254.7 272.0 — — 530.3 Covered Bonds 3,361.7 — — — — 3,361.7 Certificates of Deposit — — — — 726.3 726.3 Sub-Sovereign, Supranational and Non-U.S. Agency Bonds 2,423.6 966.9 — — — 3,390.5 Other Asset-Backed 645.8 — — — — 645.8 Other — — — — 442.6 442.6 Total $ 6,872.7 $ 2,491.9 $ 6,172.5 $ 48.0 $ 1,168.9 $ 16,754.0
Schedule of Realized Gain (Loss)	TABLE 47: INVESTMENT SECURITY GAINS AND LOSSES THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Gross Realized Debt Securities Gains $ — $ 0.1 $ 3.4 $ 1.6 Gross Realized Debt Securities Losses — (0.4) (3.3) (2.2) Changes in Other-Than-Temporary Impairment Losses (1) — (0.1) — (0.3) Net Investment Security (Losses) Gains $ — $ (0.4) $ 0.1 $ (0.9)

Securities Sold Under Agreeme_2

Securities Sold Under Agreements to Repurchase (Tables)	9 Months Ended
	Sep. 30, 2020
Banking and Thrift, Other Disclosures [Abstract]
Repurchase Agreements Accounted for as Secured Borrowings	The following table provides information regarding repurchase agreements that are accounted for as secured borrowings as of September 30, 2020 and December 31, 2019. TABLE 48: REPURCHASE AGREEMENTS ACCOUNTED FOR AS SECURED BORROWINGS REMAINING CONTRACTUAL MATURITY OF THE AGREEMENTS OVERNIGHT AND CONTINUOUS ($ In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 U.S. Treasury and Agency Securities $ 269.8 $ 489.7 Total Borrowings 269.8 489.7 Gross Amount of Recognized Liabilities for Repurchase Agreements in Note 21 269.8 489.7 Amounts related to agreements not included in Note 21 — —

Loans and Leases (Tables)

Loans and Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Loans and Leases	Amounts outstanding for loans and leases, by segment and class, are shown in the following table. During the first quarter of 2020, the Corporation implemented a change in the classification of certain loans and leases to specific segments to enhance the consistency of its reporting across various regulatory regimes. As a result, the loan and lease balances as of December 31, 2019 below have been adjusted to conform to the presentation for periods ended after such date. The adjustments generally reflect reclassification of loans from the commercial real estate class to commercial and institutional, residential real estate, and private client classes. There was no impact on total loans and leases previously reported. TABLE 49: LOANS AND LEASES (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Commercial Commercial and Institutional $ 9,524.0 $ 9,091.1 Commercial Real Estate 3,373.6 3,104.3 Non-U.S. 1,441.0 1,576.3 Lease Financing, net 30.1 65.6 Other 213.0 164.0 Total Commercial 14,581.7 14,001.3 Personal Private Client 11,893.0 11,071.4 Residential Real Estate 5,928.3 6,095.0 Non-U.S. 338.7 174.8 Other 24.6 67.1 Total Personal 18,184.6 17,408.3 Total Loans and Leases $ 32,766.3 $ 31,409.6
Borrower Ratings	Loan and lease segment and class balances as of September 30, 2020 are provided in the following table, segregated by borrower ratings into “1 to 3,” “4 to 5” and “6 to 9” (watch list and nonaccrual status) categories by year of origination at amortized cost basis. Loans that are held for investment are reported at the principal amount outstanding, net of unearned income. TABLE 50: CREDIT QUALITY INDICATOR AT AMORTIZED COST BASIS BY ORIGINATION YEAR September 30, 2020 TERM LOANS AND LEASES REVOLVING LOANS REVOLVING LOANS CONVERTED TO TERM LOANS (In Millions) 2020 2019 2018 2017 2016 PRIOR TOTAL Commercial Commercial and Institutional Risk Rating: 1 to 3 Category $ 245.2 $ 571.6 $ 208.2 $ 142.8 $ 457.8 $ 465.2 $ 3,286.6 $ 2.0 $ 5,379.4 4 to 5 Category 614.0 579.5 379.7 428.4 143.0 180.4 1,346.4 50.1 3,721.5 6 to 9 Category 36.7 134.7 39.0 29.0 38.5 20.5 124.7 — 423.1 Total Commercial and Institutional 895.9 1,285.8 626.9 600.2 639.3 666.1 4,757.7 52.1 9,524.0 Commercial Real Estate Risk Rating: 1 to 3 Category 359.5 205.7 71.8 40.5 24.9 113.4 126.5 8.9 951.2 4 to 5 Category 453.4 758.0 294.1 110.6 178.5 383.9 72.4 13.7 2,264.6 6 to 9 Category 7.5 55.2 32.5 32.0 1.6 29.0 — — 157.8 Total Commercial Real Estate 820.4 1,018.9 398.4 183.1 205.0 526.3 198.9 22.6 3,373.6 Non-U.S. Risk Rating: 1 to 3 Category 790.8 15.9 10.0 10.7 — — 32.2 — 859.6 4 to 5 Category 259.5 0.6 2.0 — — 78.6 37.2 1.8 379.7 6 to 9 Category 0.7 23.1 — — — — 177.9 — 201.7 Total Non-U.S. 1,051.0 39.6 12.0 10.7 — 78.6 247.3 1.8 1,441.0 Lease Financing, net Risk Rating: 1 to 3 Category — — — — — 18.5 — — 18.5 4 to 5 Category — — — — — 11.6 — — 11.6 6 to 9 Category — — — — — — — — — Total Lease Financing, net — — — — — 30.1 — — 30.1 Other Risk Rating: 1 to 3 Category 97.7 — — — — — — — 97.7 4 to 5 Category 115.3 — — — — — — — 115.3 6 to 9 Category — — — — — — — — — Total Other 213.0 — — — — — — — 213.0 Total Commercial 2,980.3 2,344.3 1,037.3 794.0 844.3 1,301.1 5,203.9 76.5 14,581.7 Personal Private Client Risk Rating: 1 to 3 Category 466.3 394.3 56.8 67.6 34.2 150.2 5,087.1 126.1 6,382.6 4 to 5 Category 468.4 493.6 129.6 60.0 78.1 80.9 3,952.3 145.7 5,408.6 6 to 9 Category 5.6 0.5 22.4 3.2 — — 62.1 8.0 101.8 Total Private Client 940.3 888.4 208.8 130.8 112.3 231.1 9,101.5 279.8 11,893.0 Residential Real Estate Risk Rating: 1 to 3 Category 1,322.9 396.2 60.9 108.9 254.2 738.0 188.2 1.5 3,070.8 4 to 5 Category 619.8 342.5 126.6 184.2 233.8 904.6 270.2 7.4 2,689.1 6 to 9 Category 13.1 9.4 1.7 0.5 2.7 108.7 32.3 — 168.4 Total Residential Real Estate 1,955.8 748.1 189.2 293.6 490.7 1,751.3 490.7 8.9 5,928.3 Non-U.S. Risk Rating: 1 to 3 Category 8.6 21.5 — — — 1.8 28.2 — 60.1 4 to 5 Category 12.8 22.7 11.9 0.5 0.5 8.2 216.7 5.1 278.4 6 to 9 Category — — — — — 0.2 — — 0.2 Total Non-U.S. 21.4 44.2 11.9 0.5 0.5 10.2 244.9 5.1 338.7 Other Risk Rating: 1 to 3 Category 5.5 — — — — — — — 5.5 4 to 5 Category 19.1 — — — — — — — 19.1 6 to 9 Category — — — — — — — — — Total Other 24.6 — — — — — — — 24.6 Total Personal 2,942.1 1,680.7 409.9 424.9 603.5 1,992.6 9,837.1 293.8 18,184.6 Total Loans and Leases $ 5,922.4 $ 4,025.0 $ 1,447.2 $ 1,218.9 $ 1,447.8 $ 3,293.7 $ 15,041.0 $ 370.3 $ 32,766.3
Delinquency Status	The following table provides balances and delinquency status of accrual and nonaccrual loans and leases by segment and class, as well as the other real estate owned and nonaccrual asset balances, as of September 30, 2020 and December 31, 2019. TABLE 51: DELINQUENCY STATUS ACCRUAL NONACCRUAL WITH NO ALLOWANCE (In Millions) CURRENT 30 – 59 DAYS 60 – 89 DAYS 90 DAYS TOTAL ACCRUAL NONACCRUAL TOTAL LOANS September 30, 2020 Commercial Commercial and Institutional $ 9,470.9 $ 21.9 $ 0.2 $ 0.8 $ 9,493.8 $ 30.2 $ 9,524.0 $ 11.5 Commercial Real Estate 3,361.0 0.6 8.1 — 3,369.7 3.9 3,373.6 3.9 Non-U.S. 1,441.0 — — — 1,441.0 — 1,441.0 — Lease Financing, net 30.1 — — — 30.1 — 30.1 — Other 213.0 — — — 213.0 — 213.0 — Total Commercial 14,516.0 22.5 8.3 0.8 14,547.6 34.1 14,581.7 15.4 Personal Private Client 11,832.8 39.4 13.3 7.5 11,893.0 — 11,893.0 — Residential Real Estate 5,859.9 2.9 1.3 0.3 5,864.4 63.9 5,928.3 55.5 Non-U.S. 338.7 — — — 338.7 — 338.7 — Other 24.6 — — — 24.6 — 24.6 — Total Personal 18,056.0 42.3 14.6 7.8 18,120.7 63.9 18,184.6 55.5 Total Loans and Leases $ 32,572.0 $ 64.8 $ 22.9 $ 8.6 $ 32,668.3 $ 98.0 $ 32,766.3 $ 70.9 Other Real Estate Owned $ 0.9 Total Nonaccrual Assets $ 98.9 ACCRUAL NONACCRUAL WITH NO ALLOWANCE (In Millions) CURRENT 30 – 59 DAYS 60 – 89 DAYS 90 DAYS TOTAL ACCRUAL NONACCRUAL TOTAL LOANS December 31, 2019 Commercial Commercial and Institutional $ 9,068.3 $ 4.1 $ 9.9 $ 1.2 $ 9,083.5 $ 7.6 $ 9,091.1 $ 0.8 Commercial Real Estate 3,089.6 2.3 4.1 4.7 3,100.7 3.6 3,104.3 2.4 Non-U.S. 1,576.3 — — — 1,576.3 — 1,576.3 — Lease Financing, net 65.6 — — — 65.6 — 65.6 — Other 164.0 — — — 164.0 — 164.0 — Total Commercial 13,963.8 6.4 14.0 5.9 13,990.1 11.2 14,001.3 3.2 Personal Private Client 11,027.9 33.2 9.5 0.3 11,070.9 0.5 11,071.4 0.5 Residential Real Estate 5,997.7 19.8 4.9 1.2 6,023.6 71.4 6,095.0 66.4 Non-U.S 174.1 0.2 — — 174.3 0.5 174.8 0.5 Other 67.1 — — — 67.1 — 67.1 — Total Personal 17,266.8 53.2 14.4 1.5 17,335.9 72.4 17,408.3 67.4 Total Loans and Leases $ 31,230.6 $ 59.6 $ 28.4 $ 7.4 $ 31,326.0 $ 83.6 $ 31,409.6 $ 70.6 Other Real Estate Owned $ 3.2 Total Nonaccrual Assets $ 86.8
Modified Troubled Debt Restructurings	The following table provides, by segment and class, the number of TDR modifications of loans and leases during the three- and nine- month periods ended September 30, 2020 and 2019, and the recorded investments and unpaid principal balances as of September 30, 2020 and 2019. TABLE 52: TROUBLED DEBT RESTRUCTURINGS THREE MONTHS ENDED SEPTEMBER 30, 2020 NINE MONTHS ENDED SEPTEMBER 30, 2020 ($ In Millions) NUMBER OF RECORDED UNPAID NUMBER OF RECORDED UNPAID Commercial Commercial and Institutional 1 $ 1.0 $ 1.0 3 $ 25.3 $ 25.5 Total Commercial 1 1.0 1.0 3 25.3 25.5 Personal Residential Real Estate 10 17.4 17.5 16 18.3 18.7 Total Personal 10 17.4 17.5 16 18.3 18.7 Total Loans and Leases 11 $ 18.4 $ 18.5 19 $ 43.6 $ 44.2 Note: Period-end balances reflect all paydowns and charge-offs during the period. THREE MONTHS ENDED SEPTEMBER 30, 2019 NINE MONTHS ENDED SEPTEMBER 30, 2019 ($ In Millions) NUMBER OF RECORDED UNPAID NUMBER OF RECORDED UNPAID Commercial Commercial and Institutional — $ — $ — 1 $ 7.6 $ 8.8 Commercial Real Estate — — — 2 — — Total Commercial — — — 3 7.6 8.8 Personal Residential Real Estate 5 3.1 3.1 31 20.6 20.8 Total Personal 5 3.1 3.1 31 20.6 20.8 Total Loans and Leases 5 $ 3.1 $ 3.1 34 $ 28.2 $ 29.6 Note: Period-end balances reflect all paydowns and charge-offs during the period.
Schedule Of Non-Troubled Debt Restructuring Modifications	The following tables provide, by segment and class, the number of total COVID-19-related loan modifications including the loan volume and deferred principal and interest balances as of September 30, 2020, for which Northern Trust applied an exemption from TDR classification that are in active deferral (loans currently in the deferral period) or completed deferral (loans that returned to their regular payment schedule). TABLE 53: COVID-19 LOAN MODIFICATIONS NOT CONSIDERED TDRS IN ACTIVE DEFERRAL STATUS SEPTEMBER 30, 2020 ($ In Millions) NUMBER OF COVID-19 RELATED MODIFICATIONS LOAN VOLUME DEFERRED PRINCIPAL AMOUNT DEFERRED INTEREST AMOUNT Commercial Commercial and Institutional 13 $ 73.2 $ 0.3 $ 0.5 Commercial Real Estate 2 7.3 — — Total Commercial 15 $ 80.5 $ 0.3 $ 0.5 Personal Private Client 2 $ 5.2 $ — $ 0.1 Residential Real Estate 53 19.3 0.3 0.3 Total Personal 55 $ 24.5 $ 0.3 $ 0.4 Total Loans 70 $ 105.0 $ 0.6 $ 0.9 TABLE 54: COVID-19 LOAN MODIFICATIONS NOT CONSIDERED TDRS THAT HAVE COMPLETED DEFERRAL SEPTEMBER 30, 2020 ($ In Millions) NUMBER OF COVID-19 RELATED MODIFICATIONS LOAN VOLUME DEFERRED PRINCIPAL AMOUNT DEFERRED INTEREST AMOUNT Commercial Commercial and Institutional 101 $ 199.7 $ 5.0 $ 1.5 Commercial Real Estate 104 472.2 2.9 3.3 Total Commercial 205 $ 671.9 $ 7.9 $ 4.8 Personal Private Client 34 $ 177.6 $ 2.3 $ 1.1 Residential Real Estate 346 184.8 0.5 2.0 Total Personal 380 $ 362.4 $ 2.8 $ 3.1 Total Loans 585 $ 1,034.3 $ 10.7 $ 7.9 Not included in the table above are 31 loans with $34.3 million in loan balances as of June 30, 2020 that had been granted payment deferrals but have since paid off.

Allowance for Credit Losses (Ta

Allowance for Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Allowance for Credit Loss	THREE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT DEBT SECURITIES HELD TO MATURITY OTHER FINANCIAL ASSETS TOTAL Balance at Beginning of Period $ 210.2 $ 49.0 $ 6.5 $ 1.3 $ 267.0 Charge-Offs (0.8) — — — (0.8) Recoveries 1.2 — — — 1.2 Net Recoveries (Charge-Offs) 0.4 — — — 0.4 Provision for Credit Losses 4.8 (4.1) 0.4 (0.6) 0.5 Balance at End of Period $ 215.4 $ 44.9 $ 6.9 $ 0.7 $ 267.9 NINE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT DEBT SECURITIES HELD TO MATURITY OTHER FINANCIAL ASSETS TOTAL Balance at End of Prior Period $ 104.5 $ 19.9 $ — $ — $ 124.4 Cumulative Effect Adjustment (2.2) 8.9 6.6 0.4 13.7 Balance at Beginning of Period 102.3 28.8 6.6 0.4 138.1 Charge-Offs (3.0) — — — (3.0) Recoveries 5.3 — — — 5.3 Net Recoveries (Charge-Offs) 2.3 — — — 2.3 Provision for Credit Losses 110.8 16.1 0.3 0.3 127.5 Balance at End of Period $ 215.4 $ 44.9 $ 6.9 $ 0.7 $ 267.9 THREE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT TOTAL Balance at Beginning of Period $ 110.8 $ 23.3 $ 134.1 Charge-Offs (1.1) — (1.1) Recoveries 1.7 — 1.7 Net Recoveries (Charge-Offs) 0.6 — 0.6 Provision for Credit Losses (5.7) (1.3) (7.0) Balance at End of Period $ 105.7 $ 22.0 $ 127.7 NINE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT TOTAL Balance at Beginning of Period $ 112.6 $ 25.6 $ 138.2 Charge-Offs (2.7) — (2.7) Recoveries 5.7 — 5.7 Net Recoveries (Charge-Offs) 3.0 — 3.0 Provision for Credit Losses (9.9) (3.6) (13.5) Balance at End of Period $ 105.7 $ 22.0 $ 127.7 TABLE 58: CHANGES IN THE ALLOWANCE FOR CREDIT LOSSES RELATED TO LOANS AND LEASES THREE MONTHS ENDED SEPTEMBER 30, 2020 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at Beginning of Period $ 162.8 $ 47.4 $ 210.2 $ 46.1 $ 2.9 $ 49.0 Charge-Offs — (0.8) (0.8) — — — Recoveries 0.2 1.0 1.2 — — — Net Recoveries (Charge-Offs) 0.2 0.2 0.4 — — — Provision for Credit Losses (15.4) 20.2 4.8 (6.0) 1.9 (4.1) Balance at End of Period $ 147.6 $ 67.8 $ 215.4 $ 40.1 $ 4.8 $ 44.9 NINE MONTHS ENDED SEPTEMBER 30, 2020 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at End of Prior Period $ 58.1 $ 46.4 $ 104.5 $ 15.8 $ 4.1 $ 19.9 Cumulative Effect Adjustment (5.9) 3.7 (2.2) 11.9 (3.0) 8.9 Balance at Beginning of Period 52.2 50.1 102.3 27.7 1.1 28.8 Charge-Offs (0.1) (2.9) (3.0) — — — Recoveries 2.2 3.1 5.3 — — — Net Recoveries (Charge-Offs) 2.1 0.2 2.3 — — — Provision for Credit Losses 93.3 17.5 110.8 12.4 3.7 16.1 Balance at End of Period $ 147.6 $ 67.8 $ 215.4 $ 40.1 $ 4.8 $ 44.9 THREE MONTHS ENDED SEPTEMBER 30, 2019 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at Beginning of Period $ 59.9 $ 50.9 $ 110.8 $ 18.5 $ 4.8 $ 23.3 Charge-Offs — (1.1) (1.1) — — — Recoveries — 1.7 1.7 — — — Net Recoveries (Charge-Offs) — 0.6 0.6 — — — Provision for Credit Losses (1.3) (4.4) (5.7) (0.7) (0.6) (1.3) Balance at End of Period $ 58.6 $ 47.1 $ 105.7 $ 17.8 $ 4.2 $ 22.0 NINE MONTHS ENDED SEPTEMBER 30, 2019 LOANS AND LEASES UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Balance at Beginning of Period $ 57.6 $ 55.0 $ 112.6 $ 21.1 $ 4.5 $ 25.6 Charge-Offs (0.1) (2.6) (2.7) — — — Recoveries 0.7 5.0 5.7 — — — Net Recoveries (Charge-Offs) 0.6 2.4 3.0 — — — Provision for Credit Losses 0.4 (10.3) (9.9) (3.3) (0.3) (3.6) Balance at End of Period $ 58.6 $ 47.1 $ 105.7 $ 17.8 $ 4.2 $ 22.0 The following table provides information regarding the recorded investments in loans and leases and the allowance for credit losses for loans and leases and undrawn loan commitments and standby letters of credit by segment as of September 30, 2020 and December 31, 2019. TABLE 59: RECORDED INVESTMENTS IN LOANS AND LEASES SEPTEMBER 30, 2020 DECEMBER 31, 2019 (In Millions) COMMERCIAL PERSONAL TOTAL COMMERCIAL PERSONAL TOTAL Loans and Leases Evaluated on an Individual Level $ 34.1 $ 63.9 $ 98.0 $ 10.4 $ 81.8 $ 92.2 Evaluated on a Collective Level 14,547.6 18,120.7 32,668.3 13,990.9 17,326.5 31,317.4 Total Loans and Leases 14,581.7 18,184.6 32,766.3 14,001.3 17,408.3 31,409.6 Allowance for Credit Losses on Credit Exposures Evaluated on an Individual Level 5.6 0.4 6.0 3.4 1.6 5.0 Evaluated on a Collective Level 142.0 67.4 209.4 54.7 44.8 99.5 Allowance Assigned to Loans and Leases 147.6 67.8 215.4 58.1 46.4 104.5 Allowance for Undrawn Loan Commitments and Standby Letters of Credit Evaluated on an Individual Level 2.2 — 2.2 1.9 — 1.9 Evaluated on a Collective Level 37.9 4.8 42.7 13.9 4.1 18.0 Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit 40.1 4.8 44.9 15.8 4.1 19.9 Total Allowance Assigned to Loans and Leases and Undrawn Loan Commitments and Standby Letters of Credit $ 187.7 $ 72.6 $ 260.3 $ 73.9 $ 50.5 $ 124.4
Schedule of Accrued Liabilities	The following table provides the amount of accrued interest excluded from the amortized cost basis of the following portfolios. TABLE 56: ACCRUED INTEREST (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Loans and Leases $ 54.2 $ 84.5 Debt Securities Held to Maturity $ 71.7 $ 82.3 Available for Sale 101.0 119.0 Other Financial Assets $ 1.7 $ 14.7 The following table provides amounts of accrued interest reversed through interest income by segment for the loan and lease portfolio. TABLE 57: ACCRUED INTEREST REVERSED THROUGH INCOME THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2020 Commercial $ 0.5 $ 1.5 Personal 0.6 $ 2.0 Total Loans and Leases $ 1.1 $ 3.5
Debt Securities, Held-to-maturity, Allowance for Credit Loss	THREE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) CORPORATE DEBT NON-U.S. GOVERNMENT SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS CERTIFICATE OF DEPOSITS COVERED BONDS OTHER TOTAL Balance at Beginning of Period $ 0.5 $ 0.4 $ 0.7 $ — $ — $ 4.9 $ 6.5 Provision for Credit Losses 0.2 — (0.1) 0.2 0.1 — 0.4 Balance at End of Period $ 0.7 $ 0.4 $ 0.6 $ 0.2 $ 0.1 $ 4.9 $ 6.9 NINE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) CORPORATE DEBT NON-U.S. GOVERNMENT SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS CERTIFICATE OF DEPOSITS COVERED BONDS OTHER TOTAL Balance at End of Prior Period $ — $ — $ — $ — $ — $ — $ — Cumulative Effect Adjustment 0.8 0.3 0.9 — — 4.6 6.6 Balance at Beginning of Period 0.8 0.3 0.9 — — 4.6 6.6 Provision for Credit Losses (0.1) 0.1 (0.3) 0.2 0.1 0.3 0.3 Balance at End of Period $ 0.7 $ 0.4 $ 0.6 $ 0.2 $ 0.1 $ 4.9 $ 6.9

Pledged Assets (Tables)

Pledged Assets (Tables)	9 Months Ended
	Sep. 30, 2020
Transfers and Servicing [Abstract]
Schedule of Financial Instruments Owned and Pledged as Collateral	The following table presents Northern Trust's pledged assets. TABLE 61: TYPE OF PLEDGED ASSETS (In Billions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Securities Obligations of States and Political Subdivisions $ 1.6 $ 1.0 Government Sponsored Agency and Other Securities 30.0 33.4 Loans 11.8 7.7 Total Pledged Assets $ 43.4 $ 42.1 The following table presents the available for sale debt securities pledged as collateral that are included in pledged assets. TABLE 62: FAIR VALUE OF AVAILABLE FOR SALE DEBT SECURITIES INCLUDED IN PLEDGED ASSETS SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE DERIVATIVE CONTRACTS (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 SEPTEMBER 30, 2020 DECEMBER 31, 2019 Debt Securities Available for Sale $ 268.6 $ 487.1 $ 30.0 $ 14.4
Schedule of Customer Securities for which Entity has Right to Sell or Repledge	The following table presents the fair value of securities accepted as collateral. There was no repledged or sold collateral at September 30, 2020 or December 31, 2019. TABLE 63: ACCEPTED COLLATERAL (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Collateral that may be repledged or sold Reverse repurchase agreements $ 1,533.4 $ 707.8 Derivative contracts 30.6 16.8

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Reporting Segment	Changes by reporting segment in the carrying amount of goodwill for the nine months ended September 30, 2020, including the effect of foreign exchange rates on non-U.S.-dollar denominated balances, were as follows: TABLE 64: GOODWILL BY REPORTING SEGMENT (In Millions) CORPORATE & INSTITUTIONAL SERVICES WEALTH MANAGEMENT TOTAL Balance at December 31, 2019 $ 625.7 $ 71.1 $ 696.8 Foreign Exchange Rates 1.2 — 1.2 Balance at September 30, 2020 $ 626.9 $ 71.1 $ 698.0
Other Intangible Assets	The gross carrying amount and accumulated amortization of other intangible assets subject to amortization as of September 30, 2020 and December 31, 2019 were as follows: TABLE 65: OTHER INTANGIBLE ASSETS (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Gross Carrying Amount $ 214.3 $ 207.2 Less: Accumulated Amortization 101.7 86.6 Net Book Value $ 112.6 $ 120.6

Reporting Segments (Tables)

Reporting Segments (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Results of Reporting Segments	The following table reflects the earnings contributions and average assets of Northern Trust’s reporting segments for the three- and nine- month periods ended September 30, 2020 and 2019. TABLE 66: RESULTS OF REPORTING SEGMENTS ($ In Millions) CORPORATE & WEALTH MANAGEMENT TREASURY AND OTHER TOTAL CONSOLIDATED THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 2020 2019 Noninterest Income Trust, Investment and Other Servicing Fees $ 584.9 $ 559.9 $ 418.9 $ 415.6 $ — $ — $ 1,003.8 $ 975.5 Foreign Exchange Trading Income 58.4 55.5 3.2 4.2 — — 61.6 59.7 Other Noninterest Income 56.7 53.6 39.7 38.1 (5.3) (6.7) 91.1 85.0 Total Noninterest Income 700.0 669.0 461.8 457.9 (5.3) (6.7) 1,156.5 1,120.2 Net Interest Income (1) 139.9 229.9 196.6 195.4 — — 336.5 425.3 Revenue (1) 839.9 898.9 658.4 653.3 (5.3) (6.7) 1,493.0 1,545.5 Provision for Credit Losses (19.2) 4.8 19.7 (11.8) — — 0.5 (7.0) Noninterest Expense 707.3 649.2 386.3 385.9 1.1 1.2 1,094.7 1,036.3 Income before Income Taxes (1) 151.8 244.9 252.4 279.2 (6.4) (7.9) 397.8 516.2 Provision for Income Taxes (1) 38.7 59.9 66.2 73.6 (1.6) (1.9) 103.3 131.6 Net Income $ 113.1 $ 185.0 $ 186.2 $ 205.6 $ (4.8) $ (6.0) $ 294.5 $ 384.6 Percentage of Consolidated Net Income 39 % 48 % 63 % 54 % (2) % (2) % 100 % 100 % Average Assets $ 108,823.0 $ 85,982.2 $ 32,102.4 $ 30,369.9 $ — $ — $ 140,925.4 $ 116,352.1 (1) Non-GAAP financial measures stated on a fully taxable equivalent basis (FTE). Total consolidated includes FTE adjustments of $7.9 million for 2020 and $7.6 million for 2019. ($ In Millions) CORPORATE & WEALTH MANAGEMENT TREASURY AND OTHER TOTAL CONSOLIDATED NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 2020 2019 Noninterest Income Trust, Investment and Other Servicing Fees $ 1,725.5 $ 1,644.5 $ 1,243.4 $ 1,215.4 $ — $ — $ 2,968.9 $ 2,859.9 Foreign Exchange Trading Income 211.8 172.5 10.0 13.9 — — 221.8 186.4 Other Noninterest Income 167.5 141.8 122.9 95.1 (11.0) (14.9) 279.4 222.0 Total Noninterest Income 2,104.8 1,958.8 1,376.3 1,324.4 (11.0) (14.9) 3,470.1 3,268.3 Net Interest Income (1) 516.6 694.3 615.9 585.9 — — 1,132.5 1,280.2 Revenue (1) 2,621.4 2,653.1 1,992.2 1,910.3 (11.0) (14.9) 4,602.6 4,548.5 Provision for Credit Losses 35.3 1.3 92.2 (14.8) — — 127.5 (13.5) Noninterest Expense 2,022.2 1,930.5 1,152.7 1,137.9 22.3 2.8 3,197.2 3,071.2 Income before Income Taxes (1) 563.9 721.3 747.3 787.2 (33.3) (17.7) 1,277.9 1,490.8 Provision for Income Taxes (1) 129.9 171.8 187.9 202.3 (8.3) (4.4) 309.5 369.7 Net Income $ 434.0 $ 549.5 $ 559.4 $ 584.9 $ (25.0) $ (13.3) $ 968.4 $ 1,121.1 Percentage of Consolidated Net Income 45 % 49 % 58 % 52 % (3) % (1) % 100 % 100 % Average Assets $ 102,902.3 $ 87,664.1 $ 31,742.9 $ 29,700.6 $ — $ — $ 134,645.2 $ 117,364.7 (1) Non-GAAP financial measures stated on a fully taxable equivalent basis (FTE). Total consolidated includes FTE adjustments of $23.7 million for 2020 and $23.1 million for 2019.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income (Loss)	The following tables summarize the components of accumulated other comprehensive income (loss) (AOCI) at September 30, 2020 and 2019, and changes during the three and nine months then ended. TABLE 67: SUMMARY OF CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) THREE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at June 30, 2020 $ 631.8 $ 0.3 $ 145.5 $ (407.2) $ 370.4 Net Change 33.5 1.3 1.8 17.5 54.1 Balance at September 30, 2020 $ 665.3 $ 1.6 $ 147.3 $ (389.7) $ 424.5 (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2020. NINE MONTHS ENDED SEPTEMBER 30, 2020 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at December 31, 2019 $ 114.0 $ (3.7) $ 117.8 $ (422.8) $ (194.7) Net Change 551.3 5.3 29.5 33.1 619.2 Balance at September 30, 2020 $ 665.3 $ 1.6 $ 147.3 $ (389.7) $ 424.5 (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2020. THREE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at June 30, 2019 $ 133.1 $ 4.5 $ 96.8 $ (394.2) $ (159.8) Net Change 57.0 (2.4) 9.9 4.3 68.8 Balance at September 30, 2019 $ 190.1 $ 2.1 $ 106.7 $ (389.9) $ (91.0) (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2019. NINE MONTHS ENDED SEPTEMBER 30, 2019 (In Millions) NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE (1) NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES NET FOREIGN CURRENCY ADJUSTMENT NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS TOTAL Balance at December 31, 2018 $ (114.9) $ 4.0 $ 67.9 $ (410.7) $ (453.7) Net Change 305.0 (1.9) 38.8 20.8 362.7 Balance at September 30, 2019 $ 190.1 $ 2.1 $ 106.7 $ (389.9) $ (91.0) (1) Includes net unrealized gains on debt securities transferred from available for sale to held to maturity during the period ended September 30, 2019.
Details of Changes in Accumulated Other Comprehensive Income (Loss)	TABLE 68: DETAILS OF CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 (In Millions) BEFORE TAX TAX EFFECT AFTER TAX BEFORE TAX TAX EFFECT AFTER TAX Unrealized Gains (Losses) on Debt Securities Available for Sale Unrealized Gains (Losses) on Debt Securities Available for Sale $ 45.3 $ (11.8) $ 33.5 $ 76.1 $ (19.4) $ 56.7 Reclassification Adjustment for (Gains) Losses Included in Net Income (1) — — — 0.3 — 0.3 Net Change $ 45.3 $ (11.8) $ 33.5 $ 76.4 $ (19.4) $ 57.0 Unrealized Gains (Losses) on Cash Flow Hedges Foreign Exchange Contracts $ 6.6 $ (1.6) $ 5.0 $ 0.7 $ (0.2) $ 0.5 Interest Rate Contracts (0.2) — (0.2) 0.1 — 0.1 Reclassification Adjustment for (Gains) Losses Included in Net Income (2) (4.7) 1.2 (3.5) (4.0) 1.0 (3.0) Net Change $ 1.7 $ (0.4) $ 1.3 $ (3.2) $ 0.8 $ (2.4) Foreign Currency Adjustments Foreign Currency Translation Adjustments $ 92.1 $ (3.1) $ 89.0 $ (71.9) $ 2.0 $ (69.9) Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses) 1.2 (0.3) 0.9 (1.3) 0.3 (1.0) Net Investment Hedge Gains (Losses) (117.4) 29.3 (88.1) 107.6 (26.8) 80.8 Net Change $ (24.1) $ 25.9 $ 1.8 $ 34.4 $ (24.5) $ 9.9 Pension and Other Postretirement Benefit Adjustments Net Actuarial Gains $ 12.6 $ (3.1) $ 9.5 $ — $ — $ — Reclassification Adjustment for (Gains) Losses Included in Net Income (3) Amortization of Net Actuarial Loss 10.7 (2.6) 8.1 5.7 (1.3) 4.4 Amortization of Prior Service Cost (0.1) — (0.1) (0.1) — (0.1) Net Change $ 23.2 $ (5.7) $ 17.5 $ 5.6 $ (1.3) $ 4.3 Total Net Change $ 46.1 $ 8.0 $ 54.1 $ 113.2 $ (44.4) $ 68.8 See table footnotes under the YTD table. NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 (In Millions) BEFORE TAX TAX EFFECT AFTER TAX BEFORE TAX TAX EFFECT AFTER TAX Unrealized Gains (Losses) on Debt Securities Available for Sale Unrealized Gains (Losses) on Debt Securities Available for Sale $ 736.8 $ (185.4) $ 551.4 $ 409.0 $ (104.6) $ 304.4 Reclassification Adjustment for (Gains) Losses Included in Net Income (1) (0.1) — (0.1) 0.6 — 0.6 Net Change $ 736.7 $ (185.4) $ 551.3 $ 409.6 $ (104.6) $ 305.0 Unrealized Gains (Losses) on Cash Flow Hedges Foreign Exchange Contracts $ 18.1 $ (4.5) $ 13.6 $ 17.4 $ (4.3) $ 13.1 Interest Rate Contracts 0.2 (0.1) 0.1 1.4 (0.3) 1.1 Reclassification Adjustment for (Gains) Losses Included in Net Income (2) (11.2) 2.8 (8.4) (21.4) 5.3 (16.1) Net Change $ 7.1 $ (1.8) $ 5.3 $ (2.6) $ 0.7 $ (1.9) Foreign Currency Adjustments Foreign Currency Translation Adjustments $ 53.1 $ (1.0) $ 52.1 $ (69.4) $ 3.3 $ (66.1) Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses) 0.7 (0.2) 0.5 (1.3) 0.3 (1.0) Net Investment Hedge Gains (Losses) (29.8) 6.7 (23.1) 144.1 (38.2) 105.9 Net Change $ 24.0 $ 5.5 $ 29.5 $ 73.4 $ (34.6) $ 38.8 Pension and Other Postretirement Benefit Adjustments Net Actuarial Gains (Losses) $ 11.8 $ (3.0) $ 8.8 $ 11.4 $ (3.1) $ 8.3 Reclassification Adjustment for (Gains) Losses Included in Net Income (3) Amortization of Net Actuarial Loss $ 32.3 $ (7.8) $ 24.5 $ 16.8 $ (4.1) $ 12.7 Amortization of Prior Service Cost (0.2) — (0.2) (0.2) — (0.2) Net Change $ 43.9 $ (10.8) $ 33.1 $ 28.0 $ (7.2) $ 20.8 Total Net Change $ 811.7 $ (192.5) $ 619.2 $ 508.4 $ (145.7) $ 362.7 (1) The before-tax reclassification adjustment out of AOCI related to the realized gains (losses) on debt securities available for sale is recorded as Investment Security Gains (Losses), net within the consolidated statements of income. (2) See Note 20 — Derivative Financial Instruments for the location of the reclassification adjustment related to cash flow hedges. (3) The before-tax reclassification adjustment out of AOCI related to pension and other postretirement benefit adjustments is recorded in Employee Benefits expense within the consolidated statements of income.

Net Income Per Common Share C_2

Net Income Per Common Share Computations (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Income per Common Share	The computations of net income per common share are presented in the following table. TABLE 69: NET INCOME PER COMMON SHARE THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, ($ In Millions Except Per Common Share Information) 2020 2019 2020 2019 Basic Net Income Per Common Share Average Number of Common Shares Outstanding 208,106,190 213,176,809 208,351,088 215,832,347 Net Income $ 294.5 $ 384.6 $ 968.4 $ 1,121.1 Less: Dividends on Preferred Stock 16.2 17.4 51.5 40.6 Net Income Applicable to Common Stock 278.3 367.2 916.9 1,080.5 Less: Earnings Allocated to Participating Securities 3.3 4.5 10.6 12.6 Earnings Allocated to Common Shares Outstanding 275.0 362.7 906.3 1,067.9 Basic Net Income Per Common Share $ 1.32 $ 1.70 $ 4.35 $ 4.95 Diluted Net Income Per Common Share Average Number of Common Shares Outstanding 208,106,190 213,176,809 208,351,088 215,832,347 Plus: Dilutive Effect of Share-based Compensation 582,304 1,029,767 672,243 1,031,216 Average Common and Potential Common Shares 208,688,494 214,206,576 209,023,331 216,863,563 Earnings Allocated to Common and Potential Common Shares $ 275.0 $ 362.7 $ 906.3 $ 1,067.9 Diluted Net Income Per Common Share 1.32 1.69 4.34 4.92

Revenue from Contracts with C_2

Revenue from Contracts with Clients (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue Disaggregation	The following table presents revenues disaggregated by major revenue source. TABLE 70: REVENUE DISAGGREGATION THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Noninterest Income Trust, Investment and Other Servicing Fees Custody and Fund Administration $ 416.4 $ 414.8 $ 1,231.7 $ 1,219.7 Investment Management and Advisory 519.3 491.4 1,515.2 1,428.7 Securities Lending 19.8 20.1 70.7 64.9 Other 48.3 49.2 151.3 146.6 Total Trust, Investment and Other Servicing Fees $ 1,003.8 $ 975.5 $ 2,968.9 $ 2,859.9 Other Noninterest Income Foreign Exchange Trading Income $ 61.6 $ 59.7 $ 221.8 $ 186.4 Treasury Management Fees 11.6 11.2 34.0 34.1 Security Commissions and Trading Income 26.0 29.1 100.9 75.8 Other Operating Income 53.5 45.1 144.4 113.0 Investment Security Gains (Losses), net — (0.4) 0.1 (0.9) Total Other Noninterest Income $ 152.7 $ 144.7 $ 501.2 $ 408.4 Total Noninterest Income $ 1,156.5 $ 1,120.2 $ 3,470.1 $ 3,268.3
Contract Balances	The table below represents receivables balances from contracts with clients, which are included in Other Assets on the consolidated balance sheets, at September 30, 2020 and December 31, 2019. TABLE 71: CLIENT RECEIVABLES (In Millions) SEPTEMBER 30, 2020 DECEMBER 31, 2019 Trust Fees Receivable, net (1) $ 805.7 $ 801.9 Other 113.2 101.1 Total Client Receivables $ 918.9 $ 903.0 (1) Trust Fees Receivable is net of a $7.3 million and $5.6 million fee receivable allowance as of September 30, 2020 and December 31, 2019, respectively.

Net Interest Income (Tables)

Net Interest Income (Tables)	9 Months Ended
	Sep. 30, 2020
Banking and Thrift, Interest [Abstract]
Net Interest Income	The components of net interest income were as follows: TABLE 72: NET INTEREST INCOME THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Interest Income Loans and Leases $ 167.1 $ 291.0 $ 606.4 $ 889.8 Securities — Taxable 182.6 265.9 632.1 812.4 — Non-Taxable 0.3 0.9 1.1 3.1 Interest-Bearing Due from and Deposits with Banks (1) 2.7 18.6 20.0 55.7 Federal Reserve and Other Central Bank Deposits and Other 2.7 44.4 31.3 162.8 Total Interest Income $ 355.4 $ 620.8 $ 1,290.9 $ 1,923.8 Interest Expense Deposits $ (3.5) $ 122.0 $ 56.7 $ 403.5 Federal Funds Purchased 0.1 2.4 2.1 22.8 Securities Sold Under Agreements to Repurchase — 1.6 1.0 5.4 Other Borrowings 5.0 46.0 40.6 145.2 Senior Notes 19.1 19.6 57.0 54.0 Long-Term Debt 5.7 9.4 21.1 29.4 Floating Rate Capital Debt 0.4 2.1 3.6 6.4 Total Interest Expense $ 26.8 $ 203.1 $ 182.1 $ 666.7 Net Interest Income $ 328.6 $ 417.7 $ 1,108.8 $ 1,257.1 (1) Interest-Bearing Due from and Deposits with Banks includes the interest-bearing component of Cash and Due from Banks and Interest-Bearing Deposits with Banks as presented on the consolidated balance sheets.

Pension and Postretirement He_2

Pension and Postretirement Health Care (Tables)	9 Months Ended
	Sep. 30, 2020
Retirement Benefits [Abstract]
Net Periodic Pension Expense (Benefit)	The following table sets forth the net periodic pension and postretirement benefit expense for Northern Trust’s U.S. Qualified Plan, Non-U.S. Pension Plans, U.S. Non-Qualified Plan, and postretirement health care plan for the three and nine months ended September 30, 2020 and 2019. TABLE 73: NET PERIODIC PENSION EXPENSE (BENEFIT) U.S. QUALIFIED PLAN THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Service Cost $ 11.9 $ 10.4 $ 35.5 $ 31.2 Interest Cost 10.8 11.8 32.4 35.4 Expected Return on Plan Assets (19.2) (21.7) (57.6) (65.1) Amortization Net Actuarial Loss 8.8 4.3 26.4 12.9 Prior Service Cost (0.1) (0.1) (0.3) (0.3) Net Periodic Pension Expense $ 12.2 $ 4.7 $ 36.4 $ 14.1 NON-U.S. PENSION PLANS THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Service Cost $ 0.6 $ 0.5 $ 1.6 $ 1.5 Interest Cost 0.7 0.9 2.1 2.9 Expected Return on Plan Assets (0.8) (1.0) (2.3) (2.9) Settlement Expense 0.1 — 0.3 — Amortization Net Actuarial Loss 0.2 0.2 0.8 0.5 Prior Service Cost 0.1 — 0.1 — Net Periodic Pension Expense $ 0.9 $ 0.6 $ 2.6 $ 2.0 U.S. NON-QUALIFIED PLAN THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Service Cost $ 1.2 $ 1.1 $ 3.4 $ 3.1 Interest Cost 1.2 1.5 3.6 4.4 Amortization Net Actuarial Loss 1.7 1.4 5.3 4.2 Prior Service Cost — — 0.1 0.1 Net Periodic Pension Expense $ 4.1 $ 4.0 $ 12.4 $ 11.8 POSTRETIREMENT HEALTH CARE PLAN THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Interest Cost $ 0.2 $ 0.3 $ 0.6 $ 0.9 Amortization Net Actuarial (Gain) (0.1) (0.2) (0.5) (0.8) Prior Service Cost (0.1) — (0.1) — Net Periodic Postretirement Expense $ — $ 0.1 $ — $ 0.1

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Total Compensation Expense for Share-Based Payment Arrangements	Total compensation expense for share-based payment arrangements and the associated tax impacts were as follows for the three and nine months ended September 30, 2020 and 2019. TABLE 74: TOTAL COMPENSATION EXPENSE FOR SHARE-BASED PAYMENT ARRANGEMENTS THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, (In Millions) 2020 2019 2020 2019 Restricted Stock Unit Awards $ 12.2 $ 14.0 $ 66.3 $ 68.5 Stock Options 0.1 0.4 0.4 1.1 Performance Stock Units 1.6 2.9 16.1 21.7 Total Share-Based Compensation Expense 13.9 17.3 82.8 91.3 Tax Benefits Recognized $ 3.5 $ 4.3 $ 20.6 $ 22.7

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional and Fair Value Amounts of Client-related and Trading Derivative Financial Instruments	The following table shows the notional and fair values of all derivative financial instruments as of September 30, 2020 and December 31, 2019. TABLE 75: NOTIONAL AND FAIR VALUES OF DERIVATIVE FINANCIAL INSTRUMENTS SEPTEMBER 30, 2020 DECEMBER 31, 2019 NOTIONAL VALUE FAIR VALUE NOTIONAL VALUE FAIR VALUE (In Millions) ASSET (1) LIABILITY (2) ASSET (1) LIABILITY (2) Derivatives Designated as Hedging under GAAP Interest Rate Contracts Fair Value Hedges $ 5,357.8 $ 10.2 $ 18.9 $ 4,538.2 $ 20.3 $ 20.9 Cash Flow Hedges 150.0 0.3 — 200.0 0.2 0.2 Foreign Exchange Contracts Cash Flow Hedges 5,882.7 14.0 28.9 1,661.5 8.5 11.5 Net Investment Hedges 3,165.3 20.8 83.3 2,873.8 73.7 11.9 Total Derivatives Designated as Hedging under GAAP $ 14,555.8 $ 45.3 $ 131.1 $ 9,273.5 $ 102.7 $ 44.5 Derivatives Not Designated as Hedging under GAAP Non-Designated Risk Management Derivatives Foreign Exchange Contracts $ 79.2 $ 2.0 $ 0.6 $ 176.5 $ 0.9 $ 0.7 Other Financial Derivatives (3) 681.5 — 32.3 640.3 — 33.4 Total Non-Designated Risk Management Derivatives $ 760.7 $ 2.0 $ 32.9 $ 816.8 $ 0.9 $ 34.1 Client-Related and Trading Derivatives Foreign Exchange Contracts $ 255,799.4 $ 2,242.7 $ 2,213.5 $ 291,533.6 $ 3,151.7 $ 3,158.1 Interest Rate Contracts 10,213.8 323.2 123.3 8,976.8 132.4 76.3 Total Client-Related and Trading Derivatives $ 266,013.2 $ 2,565.9 $ 2,336.8 $ 300,510.4 $ 3,284.1 $ 3,234.4 Total Derivatives Not Designated as Hedging under GAAP $ 266,773.9 $ 2,567.9 $ 2,369.7 $ 301,327.2 $ 3,285.0 $ 3,268.5 Total Gross Derivatives $ 281,329.7 $ 2,613.2 $ 2,500.8 $ 310,600.7 $ 3,387.7 $ 3,313.0 Less: Netting (4) 1,408.3 1,603.3 2,338.0 1,618.4 Total Derivative Financial Instruments $ 1,204.9 $ 897.5 $ 1,049.7 $ 1,694.6 (1) Derivative assets are reported in Other Assets on the consolidated balance sheets. (2) Derivative liabilities are reported in Other Liabilities on the consolidated balance sheets. (3) This line includes swaps related to sales of certain Visa Class B common shares. (4) See further detail in Note 21 — Offsetting of Assets and Liabilities.
Cash Flow Hedge Derivative Gains and Losses Recognized in AOCI and Reclassified to Income	The following tables provide fair value and cash flow hedge derivative gains and losses recognized in income during the three- and nine- month periods ended September 30, 2020 and 2019. TABLE 76: LOCATION AND AMOUNT OF FAIR VALUE AND CASH FLOW HEDGE DERIVATIVE GAINS AND LOSSES RECORDED IN INCOME (In Millions) INTEREST INCOME INTEREST EXPENSE OTHER OPERATING INCOME THREE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 Total amounts on the consolidated statements of income $ 355.4 $ 620.8 $ 26.8 $ 203.1 $ 53.5 $ 45.1 Gains (Losses) on fair value hedges recognized on Interest Rate Contracts Recognized on derivatives 15.1 (14.9) (2.9) 51.4 — — Recognized on hedged items (15.1) 14.9 2.9 (51.4) — — Amounts related to interest settlements on derivatives (14.2) 2.8 (2.5) (6.0) — — Total gains (losses) recognized on fair value hedges $ (14.2) $ 2.8 $ (2.5) $ (6.0) $ — $ — Gains (Losses) on cash flow hedges recognized on Foreign Exchange Contracts Net gains (losses) reclassified from AOCI to net income $ 4.2 $ 2.7 $ — $ — $ 0.3 $ 1.4 Interest Rate Contracts Net gains (losses) reclassified from AOCI to net income 0.2 (0.1) — — — — Total gains (losses) reclassified from AOCI to net income on cash flow hedges $ 4.4 $ 2.6 $ — $ — $ 0.3 $ 1.4 (In Millions) INTEREST INCOME INTEREST EXPENSE OTHER OPERATING INCOME NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 2020 2019 Total amounts on the consolidated statements of income $ 1,290.9 $ 1,923.8 $ 182.1 $ 666.7 $ 144.4 $ 113.0 Gains (Losses) on fair value hedges recognized on Interest Rate Contracts Recognized on derivatives (75.6) (99.0) 152.1 141.6 — — Recognized on hedged items 75.6 99.0 (152.1) (141.6) — — Amounts related to interest settlements on derivatives (11.6) 13.3 6.1 (3.9) — — Total gains (losses) recognized on fair value hedges $ (11.6) $ 13.3 $ 6.1 $ (3.9) $ — $ — Gains (Losses) on cash flow hedges recognized on Foreign Exchange Contracts Net gains (losses) reclassified from AOCI to net income $ 10.8 $ 20.8 $ — $ — $ 0.1 $ 1.1 Interest Rate Contracts Net gains (losses) reclassified from AOCI to net income 0.3 (0.5) — — — — Total gains (losses) reclassified from AOCI to net income on cash flow hedges $ 11.1 $ 20.3 $ — $ — $ 0.1 $ 1.1
Location and Amount of Fair Value Hedge Derivative Gains and Losses Recorded in Income	The following table provides the impact of fair value hedge accounting on the carrying value of the designated hedged items as of September 30, 2020 and December 31, 2019. TABLE 77: HEDGED ITEMS IN FAIR VALUE HEDGES SEPTEMBER 30, 2020 DECEMBER 31, 2019 (In Millions) CARRYING VALUE OF THE HEDGED ITEMS CUMULATIVE HEDGE ACCOUNTING BASIS ADJUSTMENT (1) CARRYING VALUE OF THE HEDGED ITEMS CUMULATIVE HEDGE ACCOUNTING BASIS ADJUSTMENT (2) Available for Sale Debt Securities (3) $ 2,826.2 $ 63.3 $ 2,981.0 $ 3.3 Senior Notes and Long-Term Subordinated Debt 2,745.0 261.8 1,748.5 126.9 Total $ 5,571.2 $ 325.1 $ 4,729.5 $ 130.2 (1) The cumulative hedge accounting basis adjustment includes $6.7 million related to discontinued hedging relationships of available for sale debt securities as of September 30, 2020. There are no amounts related to discontinued hedging relationships in the cumulative hedge accounting basis adjustment of senior notes and long-term debt as of September 30, 2020. (2) The cumulative hedge accounting basis adjustment includes $1.5 million related to discontinued hedging relationships of available for sale debt securities as of December 31, 2019. There were no amounts related to discontinued hedging relationships in the cumulative hedge accounting basis adjustment of senior notes and long-term debt as of December 31, 2019. (3) Carrying value represents amortized cost.
Location and Amount of Gains and Losses Recorded in Income for Non-Designated Risk Management Derivative Instruments	The following table provides the location and amount of gains and losses recorded in the consolidated statements of income for the three and nine months ended September 30, 2020 and 2019 for derivative instruments not designated as hedges under GAAP. TABLE 78: LOCATION AND AMOUNT OF GAINS AND LOSSES RECORDED IN INCOME FOR DERIVATIVES NOT DESIGNATED AS HEDGING UNDER GAAP (In Millions) DERIVATIVE GAINS (LOSSES) LOCATION RECOGNIZED IN INCOME AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Non-designated risk management derivatives Foreign Exchange Contracts Other Operating Income $ 4.2 $ (1.8) $ 3.8 $ (1.7) Other Financial Derivatives (1) Other Operating Income (5.3) (6.4) (11.0) (17.8) Gains (Losses) from non-designated risk management derivatives $ (1.1) $ (8.2) $ (7.2) $ (19.5) Client-related and trading derivatives Foreign Exchange Contracts Foreign Exchange Trading Income $ 61.6 $ 59.7 $ 221.8 $ 186.4 Interest Rate Contracts Security Commissions and Trading Income 2.3 4.9 18.5 9.2 Gains (Losses) from client-related and trading derivatives $ 63.9 $ 64.6 $ 240.3 $ 195.6 Total gains (losses) from derivatives not designated as hedging under GAAP $ 62.8 $ 56.4 $ 233.1 $ 176.1 (1) This line includes swaps related to the sale of certain Visa Class B common shares and total return swap contracts.

Offsetting of Assets and Liab_2

Offsetting of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Offsetting of Derivative Assets and Securities Purchased Under Agreements to Resell	The following table provides information regarding the offsetting of derivative assets and securities purchased under agreements to resell within the consolidated balance sheets as of September 30, 2020 and December 31, 2019. TABLE 79: OFFSETTING OF DERIVATIVE ASSETS AND SECURITIES PURCHASED UNDER AGREEMENTS TO RESELL SEPTEMBER 30, 2020 (In Millions) GROSS RECOGNIZED ASSETS GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (4) Derivative Assets (1) Foreign Exchange Contracts Over the Counter (OTC) $ 1,764.3 $ 1,405.7 $ 358.6 $ 29.7 $ 328.9 Interest Rate Swaps OTC 333.7 2.6 331.1 — 331.1 Total Derivatives Subject to a Master Netting Arrangement 2,098.0 1,408.3 689.7 29.7 660.0 Total Derivatives Not Subject to a Master Netting Arrangement 515.2 — 515.2 0.9 514.3 Total Derivatives 2,613.2 1,408.3 1,204.9 30.6 1,174.3 Securities Purchased under Agreements to Resell (3) $ 1,533.4 $ — $ 1,533.4 $ 1,533.4 $ — DECEMBER 31, 2019 (In Millions) GROSS RECOGNIZED ASSETS GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (4) Derivative Assets (1) Foreign Exchange Contracts OTC $ 2,691.1 $ 2,334.1 $ 357.0 $ 16.5 $ 340.5 Interest Rate Swaps OTC 151.9 3.9 148.0 — 148.0 Interest Rate Swaps Exchange Cleared 1.0 — 1.0 — 1.0 Total Derivatives Subject to a Master Netting Arrangement 2,844.0 2,338.0 506.0 16.5 489.5 Total Derivatives Not Subject to a Master Netting Arrangement 543.7 — 543.7 0.3 543.4 Total Derivatives 3,387.7 2,338.0 1,049.7 16.8 1,032.9 Securities Purchased under Agreements to Resell (3) $ 707.8 $ — $ 707.8 $ 707.8 $ — (1) Derivative assets are reported in Other Assets on the consolidated balance sheets. Other Assets (excluding derivative assets) totaled $7.3 billion and $7.4 billion as of September 30, 2020 and December 31, 2019, respectively. (2) Including cash collateral received from counterparties. (3) Securities purchased under agreements to resell are reported in Federal Funds Sold and Securities Purchased under Agreements to Resell on the consolidated balance sheets. There were no Federal Funds Sold as of September 30, 2020 and $5.0 million of Federal Funds Sold as of December 31, 2019. (4) Northern Trust did not possess any cash collateral that was not offset in the consolidated balance sheets that could have been used to offset the net amounts presented in the consolidated balance sheets as of September 30, 2020 and December 31, 2019.
Offsetting of Derivative Liabilities and Securities Sold Under Agreements to Repurchase	The following table provides information regarding the offsetting of derivative liabilities and securities sold under agreements to repurchase within the consolidated balance sheets as of September 30, 2020 and December 31, 2019. TABLE 80: OFFSETTING OF DERIVATIVE LIABILITIES AND SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE SEPTEMBER 30, 2020 (In Millions) GROSS RECOGNIZED LIABILITIES GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (3) Derivative Liabilities (1) Foreign Exchange Contracts OTC $ 1,969.2 $ 1,493.6 $ 475.6 $ — $ 475.6 Interest Rate Swaps OTC 142.3 109.7 32.6 — 32.6 Other Financial Derivatives 32.3 — 32.3 — 32.3 Total Derivatives Subject to a Master Netting Arrangement 2,143.8 1,603.3 540.5 — 540.5 Total Derivatives Not Subject to a Master Netting Arrangement 357.0 — 357.0 — 357.0 Total Derivatives 2,500.8 1,603.3 897.5 — 897.5 Securities Sold under Agreements to Repurchase $ 269.8 $ — $ 269.8 $ 269.8 $ — DECEMBER 31, 2019 (In Millions) GROSS RECOGNIZED LIABILITIES GROSS AMOUNTS OFFSET IN THE BALANCE SHEET (2) NET AMOUNTS PRESENTED IN THE BALANCE SHEET GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET NET AMOUNT (3) Derivative Liabilities (1) Foreign Exchange Contracts OTC $ 2,181.6 $ 1,548.6 $ 633.0 $ 0.1 $ 632.9 Interest Rate Swaps OTC 96.7 57.3 39.4 — 39.4 Interest Rate Swaps Exchange Cleared 0.7 — 0.7 — 0.7 Other Financial Derivatives 33.4 12.5 20.9 — 20.9 Total Derivatives Subject to a Master Netting Arrangement 2,312.4 1,618.4 694.0 0.1 693.9 Total Derivatives Not Subject to a Master Netting Arrangement 1,000.6 — 1,000.6 — 1,000.6 Total Derivatives 3,313.0 1,618.4 1,694.6 0.1 1,694.5 Securities Sold under Agreements to Repurchase $ 489.7 $ — $ 489.7 $ 489.7 $ — (1) Derivative liabilities are reported in Other Liabilities on the consolidated balance sheets. Other Liabilities (excluding derivative liabilities) totaled $3.6 billion and $3.1 billion as of September 30, 2020 and December 31, 2019, respectively. (2) Including cash collateral deposited with counterparties. (3) Northern Trust did not place any cash collateral with counterparties that was not offset in the consolidated balance sheets that could have been used to offset the net amounts presented in the consolidated balance sheets as of September 30, 2020 and December 31, 2019.

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	Jan. 01, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Allowance for credit loss		$ 215.4	$ 210.2		$ 104.5	$ 105.7	$ 110.8		$ 112.6
Stockholders equity		(11,579.1)	(11,382.2)	$ (10,879.7)	(11,091)	(10,811.3)	(10,805.5)	$ (10,616.2)	(10,508.3)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders equity		$ (12,118.3)	$ (11,988.4)	$ (11,828.1)	(11,656.7)	$ (11,441.2)	$ (11,225.5)	$ (10,972.9)	$ (10,776.8)
Cumulative Effect Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss	$ 13.7				(2.2)
Stockholders equity					10.1
Cumulative Effect Adjustment | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders equity	$ 10.1				$ 10.1

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) shares in Millions, $ in Millions	Sep. 30, 2020USD ($)security	Dec. 31, 2019USD ($)security	Jun. 30, 2016shares	Jun. 30, 2015shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale	$ 42,551	$ 38,876.3
Trading account securities	$ 0.6	$ 0.3
Visa Class B
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares issued (in shares) | shares			1.1	1
LEVEL 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of available for sale securities portfolio | security	2,086	1,704
Available-for-sale	$ 38,400	$ 34,300
LEVEL 2 | External Pricing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of available for sale securities portfolio | security		1,704
Trading account securities		$ 0.3
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, measurement input	0.152
LEVEL 3 | Fair Value, Measurements, Nonrecurring | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value	$ 21.2

Fair Value Measurements (Level

Fair Value Measurements (Level 3 Significant Unobservable Inputs) (Details) $ in Millions	Sep. 30, 2020USD ($)month	Dec. 31, 2019USD ($)month
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities | $	$ 897.5	$ 1,694.6
Swap | Fair Value, Measurements, Recurring | LEVEL 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities | $	$ 32.3	$ 33.4
Swap | Conversion Rate | Fair Value, Measurements, Recurring | LEVEL 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	1.62	1.62
Swap | Visa Class A Appreciation | Fair Value, Measurements, Recurring | LEVEL 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.0870	0.0854
Swap | Expected Duration | Fair Value, Measurements, Recurring | LEVEL 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	20	22
Swap | Expected Duration | Fair Value, Measurements, Recurring | LEVEL 3 | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	12	12
Swap | Expected Duration | Fair Value, Measurements, Recurring | LEVEL 3 | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	33	36

Fair Value Measurements (Recurr

Fair Value Measurements (Recurring Basis Hierarchy Leveling) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	$ 42,551	$ 38,876.3
Derivative Assets	2,613.2	3,387.7
NETTING	(1,408.3)	(2,338)
Derivative Assets	1,204.9	1,049.7
Derivative Liabilities	2,500.8	3,313
NETTING	(1,603.3)	(1,618.4)
Derivative Liabilities	897.5	1,694.6
Cross Product Collateral Adjustment
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(212.7)	(1,136.8)
NETTING	(407.7)	(417.2)
U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	4,165.2	4,549.1
Obligations of States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,600.5	1,615.3
Government Sponsored Agency
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	24,568.8	23,271.2
Non-U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	937.6	3.3
Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,627.4	2,402.7
Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	516.8	769.9
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,552.8	2,127.6
Other Asset-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,559.4	3,330.5
Commercial Mortgage-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,015.2	797.7
Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	7.3	9
LEVEL 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	38,400	34,300
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	42,551	38,876.3
Trading Account	0.6	0.3
Total Available for Sale and Trading Debt Securities	42,551.6	38,876.6
Fair Value, Measurements, Recurring | U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	4,165.2	4,549.1
Fair Value, Measurements, Recurring | Obligations of States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,600.5	1,615.3
Fair Value, Measurements, Recurring | Government Sponsored Agency
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	24,568.8	23,271.2
Fair Value, Measurements, Recurring | Non-U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	937.6	3.3
Fair Value, Measurements, Recurring | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,627.4	2,402.7
Fair Value, Measurements, Recurring | Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	516.8	769.9
Fair Value, Measurements, Recurring | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,552.8	2,127.6
Fair Value, Measurements, Recurring | Other Asset-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,559.4	3,330.5
Fair Value, Measurements, Recurring | Commercial Mortgage-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,015.2	797.7
Fair Value, Measurements, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	7.3	9
Fair Value, Measurements, Recurring | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(1,408.3)	(2,338)
Derivative Assets	1,204.9	1,049.7
Fair Value, Measurements, Recurring | Other Assets | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(1,405.7)	(2,334.1)
Derivative Assets	873.8	900.7
Fair Value, Measurements, Recurring | Other Assets | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(2.6)	(3.9)
Derivative Assets	331.1	149
Fair Value, Measurements, Recurring | Other Liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(1,603.3)	(1,618.4)
Derivative Liabilities	897.5	1,694.6
Fair Value, Measurements, Recurring | Other Liabilities | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(1,493.6)	(1,548.6)
Derivative Liabilities	832.7	1,633.6
Fair Value, Measurements, Recurring | Other Liabilities | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	(109.7)	(57.3)
Derivative Liabilities	32.5	40.1
Fair Value, Measurements, Recurring | Other Liabilities | Other Financial Derivatives
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
NETTING	0	(12.5)
Derivative Liabilities	32.3	20.9
Fair Value, Measurements, Recurring | LEVEL 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	4,165.2	4,549.1
Trading Account	0.3	0
Total Available for Sale and Trading Debt Securities	4,165.5	4,549.1
Fair Value, Measurements, Recurring | LEVEL 1 | U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	4,165.2	4,549.1
Fair Value, Measurements, Recurring | LEVEL 1 | Obligations of States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Government Sponsored Agency
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Non-U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Asset-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Commercial Mortgage-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Assets | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Assets | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities | Other Financial Derivatives
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	38,385.8	34,327.2
Trading Account	0.3	0.3
Total Available for Sale and Trading Debt Securities	38,386.1	34,327.5
Fair Value, Measurements, Recurring | LEVEL 2 | U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 2 | Obligations of States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,600.5	1,615.3
Fair Value, Measurements, Recurring | LEVEL 2 | Government Sponsored Agency
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	24,568.8	23,271.2
Fair Value, Measurements, Recurring | LEVEL 2 | Non-U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	937.6	3.3
Fair Value, Measurements, Recurring | LEVEL 2 | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,627.4	2,402.7
Fair Value, Measurements, Recurring | LEVEL 2 | Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	516.8	769.9
Fair Value, Measurements, Recurring | LEVEL 2 | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	2,552.8	2,127.6
Fair Value, Measurements, Recurring | LEVEL 2 | Other Asset-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	3,559.4	3,330.5
Fair Value, Measurements, Recurring | LEVEL 2 | Commercial Mortgage-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	1,015.2	797.7
Fair Value, Measurements, Recurring | LEVEL 2 | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	7.3	9
Fair Value, Measurements, Recurring | LEVEL 2 | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	2,613.2	3,387.7
Fair Value, Measurements, Recurring | LEVEL 2 | Other Assets | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	2,279.5	3,234.8
Fair Value, Measurements, Recurring | LEVEL 2 | Other Assets | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	333.7	152.9
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	2,468.5	3,279.6
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	2,326.3	3,182.2
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	142.2	97.4
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities | Other Financial Derivatives
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Trading Account	0	0
Total Available for Sale and Trading Debt Securities	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Obligations of States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Government Sponsored Agency
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Non-U.S. Government
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Asset-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Commercial Mortgage-Backed
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Assets | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Assets | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	32.3	33.4
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities | Foreign Exchange Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities | Interest Rate Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	0	0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities | Other Financial Derivatives
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Liabilities	$ 32.3	$ 33.4

Fair Value Measurements (Change

Fair Value Measurements (Changes in Level 3 Liabilities) (Details) - SWAPS RELATED TO SALE OF CERTAIN VISA CLASS B COMMON SHARES - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value liabilities beginning balance	$ 31.3	$ 34.7	$ 33.4	$ 32.8
Total (Gains) Losses:
Included in Earnings	5.3	6.7	11	14.9
Purchases, Issues, Sales, and Settlements
Settlements	(4.3)	(3.7)	(12.1)	(10)
Fair value liabilities ending balance	$ 32.3	$ 37.7	$ 32.3	$ 37.7

Fair Value Measurements (Nonrec

Fair Value Measurements (Nonrecurring Basis Significant Unobservable Inputs) (Details) - Fair Value, Measurements, Nonrecurring - LEVEL 3 $ in Millions	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019
Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FAIR VALUE	$ 21.2
Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
INPUT VALUES	0.152
Measurement Input, Discount Rate | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
INPUT VALUES	0.150	0.150
Measurement Input, Discount Rate | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
INPUT VALUES	0.200	0.200	0.200
Measurement Input, Discount Rate | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
INPUT VALUES		0.153
Loans | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FAIR VALUE	$ 21.2	$ 8

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
ASSETS
Cash and Due from Banks	$ 4,737.5	$ 4,459.2
Federal Reserve and Other Central Bank Deposits	39,244.6	33,886
Interest-Bearing Deposits with Banks	2,754.4	4,877.1
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,533.4	712.8
Debt Securities
Available-for-sale	42,551	38,876.3
Debt securities, held-to-maturity	16,754	12,284.5
Loans (excluding Leases)
Client Security Settlement Receivables	2,296.8	845.7
Deposits
Savings Certificates and Other Time	1,486.7	986.7
Non U.S. Offices Interest-Bearing	61,345.6	60,400.3
Federal Funds Purchased	2,203.7	552.9
Securities Sold Under Agreements to Repurchase	269.8	489.7
Other Borrowings	5,771.7	6,744.8
Senior Notes	3,655.6	2,573
Long-Term Debt
Floating Rate Capital Debt	277.7	277.7
Derivative Instruments
Assets	2,098	2,844
Liabilities	2,143.8	2,312.4
LEVEL 2
Debt Securities
Available-for-sale	38,400	34,300
BOOK VALUE
ASSETS
Cash and Due from Banks	4,737.5	4,459.2
Federal Reserve and Other Central Bank Deposits	39,244.6	33,886
Interest-Bearing Deposits with Banks	2,754.4	4,877.1
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,533.4	712.8
Debt Securities
Available-for-sale	42,551	38,876.3
Debt securities, held-to-maturity	16,754	12,284.5
Trading Account	0.6	0.3
Loans (excluding Leases)
Held for Investment	32,521.2	31,239.5
Client Security Settlement Receivables	2,296.8	845.7
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	239.7	301.2
Community Development Investments	761.3	749.3
Employee Benefit and Deferred Compensation	214.6	199.5
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	59,756.8	47,733.6
Savings Certificates and Other Time	1,486.7	986.7
Non U.S. Offices Interest-Bearing	61,345.6	60,400.3
Federal Funds Purchased	2,203.7	552.9
Securities Sold Under Agreements to Repurchase	269.8	489.7
Other Borrowings	5,771.7	6,744.8
Senior Notes	3,655.6	2,573
Long-Term Debt
Subordinated Debt	1,196	1,148.1
Floating Rate Capital Debt	277.7	277.7
Other Liabilities
Standby Letters of Credit	23.9	25.5
Loan Commitments	55.7	32.3
BOOK VALUE | Asset/Liability Management | Foreign Exchange Contracts
Derivative Instruments
Assets	36.8	83.1
Liabilities	112.8	24.1
BOOK VALUE | Asset/Liability Management | Interest Rate Contracts
Derivative Instruments
Assets	10.5	20.5
Liabilities	18.9	21.1
BOOK VALUE | Asset/Liability Management | Other Financial Derivatives
Derivative Instruments
Liabilities	32.3	33.4
BOOK VALUE | Client-Related and Trading | Foreign Exchange Contracts
Derivative Instruments
Assets	2,242.7	3,151.7
Liabilities	2,213.5	3,158.1
BOOK VALUE | Client-Related and Trading | Interest Rate Contracts
Derivative Instruments
Assets	323.2	132.4
Liabilities	123.3	76.3
TOTAL FAIR VALUE
ASSETS
Cash and Due from Banks	4,737.5	4,459.2
Federal Reserve and Other Central Bank Deposits	39,244.6	33,886
Interest-Bearing Deposits with Banks	2,754.4	4,877.1
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,533.4	712.8
Debt Securities
Available-for-sale	42,551	38,876.3
Debt securities, held-to-maturity	16,746.5	12,249.3
Trading Account	0.6	0.3
Loans (excluding Leases)
Held for Investment	33,001.4	31,517.8
Client Security Settlement Receivables	2,296.8	845.7
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	239.7	301.2
Community Development Investments	761.3	749.3
Employee Benefit and Deferred Compensation	230	207.6
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	59,756.8	47,733.6
Savings Certificates and Other Time	1,496.5	994.2
Non U.S. Offices Interest-Bearing	61,345.6	60,400.3
Federal Funds Purchased	2,203.7	552.9
Securities Sold Under Agreements to Repurchase	269.8	489.7
Other Borrowings	5,772.9	6,745.9
Senior Notes	3,731	2,593
Long-Term Debt
Subordinated Debt	1,250	1,169.5
Floating Rate Capital Debt	255.6	262.1
Other Liabilities
Standby Letters of Credit	23.9	25.5
Loan Commitments	55.7	32.3
TOTAL FAIR VALUE | Asset/Liability Management | Foreign Exchange Contracts
Derivative Instruments
Assets	36.8	83.1
Liabilities	112.8	24.1
TOTAL FAIR VALUE | Asset/Liability Management | Interest Rate Contracts
Derivative Instruments
Assets	10.5	20.5
Liabilities	18.9	21.1
TOTAL FAIR VALUE | Asset/Liability Management | Other Financial Derivatives
Derivative Instruments
Liabilities	32.3	33.4
TOTAL FAIR VALUE | Client-Related and Trading | Foreign Exchange Contracts
Derivative Instruments
Assets	2,242.7	3,151.7
Liabilities	2,213.5	3,158.1
TOTAL FAIR VALUE | Client-Related and Trading | Interest Rate Contracts
Derivative Instruments
Assets	323.2	132.4
Liabilities	123.3	76.3
TOTAL FAIR VALUE | LEVEL 1
ASSETS
Cash and Due from Banks	4,737.5	4,459.2
Federal Reserve and Other Central Bank Deposits	0	0
Interest-Bearing Deposits with Banks	0	0
Federal Funds Sold and Securities Purchased under Agreements to Resell	0	0
Debt Securities
Available-for-sale	4,165.2	4,549.1
Debt securities, held-to-maturity	99	138.8
Trading Account	0.3	0
Loans (excluding Leases)
Held for Investment	0	0
Client Security Settlement Receivables	0	0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	0	0
Community Development Investments	0	0
Employee Benefit and Deferred Compensation	143.6	131
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	59,756.8	47,733.6
Savings Certificates and Other Time	0	0
Non U.S. Offices Interest-Bearing	0	0
Federal Funds Purchased	0	0
Securities Sold Under Agreements to Repurchase	0	0
Other Borrowings	0	0
Senior Notes	0	0
Long-Term Debt
Subordinated Debt	0	0
Floating Rate Capital Debt	0	0
Other Liabilities
Standby Letters of Credit	0	0
Loan Commitments	0	0
TOTAL FAIR VALUE | LEVEL 1 | Asset/Liability Management | Foreign Exchange Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 1 | Asset/Liability Management | Interest Rate Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 1 | Asset/Liability Management | Other Financial Derivatives
Derivative Instruments
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 1 | Client-Related and Trading | Foreign Exchange Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 1 | Client-Related and Trading | Interest Rate Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 2
ASSETS
Cash and Due from Banks	0	0
Federal Reserve and Other Central Bank Deposits	39,244.6	33,886
Interest-Bearing Deposits with Banks	2,754.4	4,877.1
Federal Funds Sold and Securities Purchased under Agreements to Resell	1,533.4	712.8
Debt Securities
Available-for-sale	38,385.8	34,327.2
Debt securities, held-to-maturity	16,647.5	12,110.5
Trading Account	0.3	0.3
Loans (excluding Leases)
Held for Investment	0	0
Client Security Settlement Receivables	2,296.8	845.7
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	239.7	301.2
Community Development Investments	761.3	749.3
Employee Benefit and Deferred Compensation	86.4	76.6
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	0	0
Savings Certificates and Other Time	1,496.5	994.2
Non U.S. Offices Interest-Bearing	61,345.6	60,400.3
Federal Funds Purchased	2,203.7	552.9
Securities Sold Under Agreements to Repurchase	269.8	489.7
Other Borrowings	5,772.9	6,745.9
Senior Notes	3,731	2,593
Long-Term Debt
Subordinated Debt	1,250	1,169.5
Floating Rate Capital Debt	255.6	262.1
Other Liabilities
Standby Letters of Credit	0	0
Loan Commitments	0	0
TOTAL FAIR VALUE | LEVEL 2 | Asset/Liability Management | Foreign Exchange Contracts
Derivative Instruments
Assets	36.8	83.1
Liabilities	112.8	24.1
TOTAL FAIR VALUE | LEVEL 2 | Asset/Liability Management | Interest Rate Contracts
Derivative Instruments
Assets	10.5	20.5
Liabilities	18.9	21.1
TOTAL FAIR VALUE | LEVEL 2 | Asset/Liability Management | Other Financial Derivatives
Derivative Instruments
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 2 | Client-Related and Trading | Foreign Exchange Contracts
Derivative Instruments
Assets	2,242.7	3,151.7
Liabilities	2,213.5	3,158.1
TOTAL FAIR VALUE | LEVEL 2 | Client-Related and Trading | Interest Rate Contracts
Derivative Instruments
Assets	323.2	132.4
Liabilities	123.3	76.3
TOTAL FAIR VALUE | LEVEL 3
ASSETS
Cash and Due from Banks	0	0
Federal Reserve and Other Central Bank Deposits	0	0
Interest-Bearing Deposits with Banks	0	0
Federal Funds Sold and Securities Purchased under Agreements to Resell	0	0
Debt Securities
Available-for-sale	0	0
Debt securities, held-to-maturity	0	0
Trading Account	0	0
Loans (excluding Leases)
Held for Investment	33,001.4	31,517.8
Client Security Settlement Receivables	0	0
Other Assets
Federal Reserve and Federal Home Loan Bank Stock	0	0
Community Development Investments	0	0
Employee Benefit and Deferred Compensation	0	0
Deposits
Demand, Noninterest-Bearing, Savings, Money Market and Other Interest-Bearing	0	0
Savings Certificates and Other Time	0	0
Non U.S. Offices Interest-Bearing	0	0
Federal Funds Purchased	0	0
Securities Sold Under Agreements to Repurchase	0	0
Other Borrowings	0	0
Senior Notes	0	0
Long-Term Debt
Subordinated Debt	0	0
Floating Rate Capital Debt	0	0
Other Liabilities
Standby Letters of Credit	23.9	25.5
Loan Commitments	55.7	32.3
TOTAL FAIR VALUE | LEVEL 3 | Asset/Liability Management | Foreign Exchange Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 3 | Asset/Liability Management | Interest Rate Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 3 | Asset/Liability Management | Other Financial Derivatives
Derivative Instruments
Liabilities	32.3	33.4
TOTAL FAIR VALUE | LEVEL 3 | Client-Related and Trading | Foreign Exchange Contracts
Derivative Instruments
Assets	0	0
Liabilities	0	0
TOTAL FAIR VALUE | LEVEL 3 | Client-Related and Trading | Interest Rate Contracts
Derivative Instruments
Assets	0	0
Liabilities	$ 0	$ 0

Securities (Reconciliation of A

Securities (Reconciliation of Amortized Cost to Fair Value of Securities Available for Sale) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Total	$ 41,659.2	$ 38,722.2
GROSS UNREALIZED GAINS	926.8	262.7
GROSS UNREALIZED LOSSES	35	108.6
FAIR VALUE	42,551	38,876.3
U.S. Government
Investment Holdings [Line Items]
Total	4,083.9	4,527.5
GROSS UNREALIZED GAINS	81.3	26.7
GROSS UNREALIZED LOSSES	0	5.1
FAIR VALUE	4,165.2	4,549.1
Obligations of States and Political Subdivisions
Investment Holdings [Line Items]
Total	2,465.2	1,604
GROSS UNREALIZED GAINS	136.3	24.6
GROSS UNREALIZED LOSSES	1	13.3
FAIR VALUE	2,600.5	1,615.3
Government Sponsored Agency
Investment Holdings [Line Items]
Total	24,162.6	23,247.5
GROSS UNREALIZED GAINS	427.4	101.8
GROSS UNREALIZED LOSSES	21.2	78.1
FAIR VALUE	24,568.8	23,271.2
Non-U.S. Government
Investment Holdings [Line Items]
Total	936.8	3.3
GROSS UNREALIZED GAINS	0.9	0
GROSS UNREALIZED LOSSES	0.1	0
FAIR VALUE	937.6	3.3
Corporate Debt
Investment Holdings [Line Items]
Total	2,548.7	2,378.9
GROSS UNREALIZED GAINS	80.9	27.8
GROSS UNREALIZED LOSSES	2.2	4
FAIR VALUE	2,627.4	2,402.7
Covered Bonds
Investment Holdings [Line Items]
Total	508.5	766.3
GROSS UNREALIZED GAINS	8.3	4.4
GROSS UNREALIZED LOSSES	0	0.8
FAIR VALUE	516.8	769.9
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Investment Holdings [Line Items]
Total	2,486.4	2,091.3
GROSS UNREALIZED GAINS	66.7	37.4
GROSS UNREALIZED LOSSES	0.3	1.1
FAIR VALUE	2,552.8	2,127.6
Other Asset-Backed
Investment Holdings [Line Items]
Total	3,522.3	3,324.5
GROSS UNREALIZED GAINS	46.6	11.3
GROSS UNREALIZED LOSSES	9.5	5.3
FAIR VALUE	3,559.4	3,330.5
Commercial Mortgage-Backed
Investment Holdings [Line Items]
Total	937.5	769.9
GROSS UNREALIZED GAINS	78.4	28.7
GROSS UNREALIZED LOSSES	0.7	0.9
FAIR VALUE	1,015.2	797.7
Other
Investment Holdings [Line Items]
Total	7.3	9
GROSS UNREALIZED GAINS	0	0
GROSS UNREALIZED LOSSES	0	0
FAIR VALUE	$ 7.3	$ 9

Securities (Remaining Maturity

Securities (Remaining Maturity of Securities Available for Sale and Held to Maturity) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Available for Sale - Cost
Due in One Year or Less	$ 9,976.3
Due After One Year Through Five Years	19,133.2
Due After Five Years Through Ten Years	9,932.4
Due After Ten Years	2,617.3
Total	41,659.2	$ 38,722.2
Available for Sale - Value
Due in One Year or Less	10,076
Due After One Year Through Five Years	19,537.8
Due After Five Years Through Ten Years	10,258.7
Due After Ten Years	2,678.5
Total	42,551	38,876.3
Held to Maturity - Amortized Cost
Due in One Year or Less	10,516.1
Due After One Year Through Five Years	5,813.7
Due After Five Years Through Ten Years	312.7
Due After Ten Years	111.5
Total	16,754	12,284.5
Held to Maturity - Fair Value
Due in One Year or Less	10,527
Due After One Year Through Five Years	5,859.4
Due After Five Years Through Ten Years	304
Due After Ten Years	56.1
Total	16,746.5	12,249.3
U.S. Government
Available for Sale - Cost
Due in One Year or Less	1,802.3
Due After One Year Through Five Years	1,834.8
Due After Five Years Through Ten Years	446.8
Due After Ten Years	0
Total	4,083.9	4,527.5
Available for Sale - Value
Due in One Year or Less	1,805.4
Due After One Year Through Five Years	1,876.1
Due After Five Years Through Ten Years	483.7
Due After Ten Years	0
Total	4,165.2	4,549.1
Held to Maturity - Amortized Cost
Due in One Year or Less	99
Due After One Year Through Five Years	0
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	99	138.8
Held to Maturity - Fair Value
Due in One Year or Less	99
Due After One Year Through Five Years	0
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	99	138.8
Obligations of States and Political Subdivisions
Available for Sale - Cost
Due in One Year or Less	16.4
Due After One Year Through Five Years	210.9
Due After Five Years Through Ten Years	2,187.7
Due After Ten Years	50.2
Total	2,465.2	1,604
Available for Sale - Value
Due in One Year or Less	16.4
Due After One Year Through Five Years	222.8
Due After Five Years Through Ten Years	2,311
Due After Ten Years	50.3
Total	2,600.5	1,615.3
Held to Maturity - Amortized Cost
Due in One Year or Less	1.6
Due After One Year Through Five Years	1
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	2.6	10.1
Held to Maturity - Fair Value
Due in One Year or Less	1.6
Due After One Year Through Five Years	1.1
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	2.7	10.3
Government Sponsored Agency
Available for Sale - Cost
Due in One Year or Less	6,077
Due After One Year Through Five Years	9,520.9
Due After Five Years Through Ten Years	6,111.1
Due After Ten Years	2,453.6
Total	24,162.6	23,247.5
Available for Sale - Value
Due in One Year or Less	6,160.5
Due After One Year Through Five Years	9,669.4
Due After Five Years Through Ten Years	6,224.2
Due After Ten Years	2,514.7
Total	24,568.8	23,271.2
Held to Maturity - Amortized Cost
Due in One Year or Less	0.5
Due After One Year Through Five Years	1.5
Due After Five Years Through Ten Years	0.9
Due After Ten Years	0.5
Total	3.4	4.1
Held to Maturity - Fair Value
Due in One Year or Less	0.6
Due After One Year Through Five Years	1.6
Due After Five Years Through Ten Years	1
Due After Ten Years	0.5
Total	3.7	4.3
Non-U.S. Government
Available for Sale - Cost
Due in One Year or Less	737.9
Due After One Year Through Five Years	40.7
Due After Five Years Through Ten Years	158.2
Due After Ten Years	0
Total	936.8
Available for Sale - Value
Due in One Year or Less	738.2
Due After One Year Through Five Years	40.6
Due After Five Years Through Ten Years	158.8
Due After Ten Years	0
Total	937.6
Held to Maturity - Amortized Cost
Due in One Year or Less	7,291.5
Due After One Year Through Five Years	260.3
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	7,551.8	4,076
Held to Maturity - Fair Value
Due in One Year or Less	7,293.2
Due After One Year Through Five Years	266.5
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	7,559.7	4,078.8
Corporate Debt
Available for Sale - Cost
Due in One Year or Less	547.1
Due After One Year Through Five Years	2,001.6
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	2,548.7	2,378.9
Available for Sale - Value
Due in One Year or Less	552.9
Due After One Year Through Five Years	2,074.5
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	2,627.4	2,402.7
Held to Maturity - Amortized Cost
Due in One Year or Less	125
Due After One Year Through Five Years	405.3
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	530.3	405.1
Held to Maturity - Fair Value
Due in One Year or Less	125.2
Due After One Year Through Five Years	410.6
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	535.8	406.2
Covered Bonds
Available for Sale - Cost
Due in One Year or Less	24.4
Due After One Year Through Five Years	484.1
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	508.5	766.3
Available for Sale - Value
Due in One Year or Less	24.5
Due After One Year Through Five Years	492.3
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	516.8	769.9
Held to Maturity - Amortized Cost
Due in One Year or Less	1,228.1
Due After One Year Through Five Years	2,133.6
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	3,361.7	3,006.7
Held to Maturity - Fair Value
Due in One Year or Less	1,233.1
Due After One Year Through Five Years	2,153
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	3,386.1	3,020.4
Certificates of Deposit
Held to Maturity - Amortized Cost
Due in One Year or Less	726.3
Due After One Year Through Five Years	0
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	726.3	262.9
Held to Maturity - Fair Value
Due in One Year or Less	726.3
Due After One Year Through Five Years	0
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	726.3	262.9
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Available for Sale - Cost
Due in One Year or Less	334.9
Due After One Year Through Five Years	2,046
Due After Five Years Through Ten Years	105.5
Due After Ten Years	0
Total	2,486.4	2,091.3
Available for Sale - Value
Due in One Year or Less	335.1
Due After One Year Through Five Years	2,111.8
Due After Five Years Through Ten Years	105.9
Due After Ten Years	0
Total	2,552.8	2,127.6
Held to Maturity - Amortized Cost
Due in One Year or Less	832.7
Due After One Year Through Five Years	2,325.2
Due After Five Years Through Ten Years	232.6
Due After Ten Years	0
Total	3,390.5	3,285.4
Held to Maturity - Fair Value
Due in One Year or Less	837.1
Due After One Year Through Five Years	2,362.7
Due After Five Years Through Ten Years	233.2
Due After Ten Years	0
Total	3,433	3,305
Other Asset-Backed
Available for Sale - Cost
Due in One Year or Less	412.4
Due After One Year Through Five Years	2,658
Due After Five Years Through Ten Years	356
Due After Ten Years	95.9
Total	3,522.3	3,324.5
Available for Sale - Value
Due in One Year or Less	419
Due After One Year Through Five Years	2,690
Due After Five Years Through Ten Years	354.5
Due After Ten Years	95.9
Total	3,559.4	3,330.5
Held to Maturity - Amortized Cost
Due in One Year or Less	190.1
Due After One Year Through Five Years	435.4
Due After Five Years Through Ten Years	20.3
Due After Ten Years	0
Total	645.8	804.3
Held to Maturity - Fair Value
Due in One Year or Less	190.1
Due After One Year Through Five Years	435.8
Due After Five Years Through Ten Years	20.4
Due After Ten Years	0
Total	646.3	804.7
Commercial Mortgage-Backed
Available for Sale - Cost
Due in One Year or Less	16.6
Due After One Year Through Five Years	336.2
Due After Five Years Through Ten Years	567.1
Due After Ten Years	17.6
Total	937.5	769.9
Available for Sale - Value
Due in One Year or Less	16.7
Due After One Year Through Five Years	360.3
Due After Five Years Through Ten Years	620.6
Due After Ten Years	17.6
Total	1,015.2	797.7
Other
Available for Sale - Cost
Due in One Year or Less	7.3
Due After One Year Through Five Years	0
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	7.3	9
Available for Sale - Value
Due in One Year or Less	7.3
Due After One Year Through Five Years	0
Due After Five Years Through Ten Years	0
Due After Ten Years	0
Total	7.3	9
Held to Maturity - Amortized Cost
Due in One Year or Less	21.3
Due After One Year Through Five Years	251.4
Due After Five Years Through Ten Years	58.9
Due After Ten Years	111
Total	442.6	291.1
Held to Maturity - Fair Value
Due in One Year or Less	20.8
Due After One Year Through Five Years	228.1
Due After Five Years Through Ten Years	49.4
Due After Ten Years	55.6
Total	$ 353.9	$ 217.9

Securities (Securities with Unr

Securities (Securities with Unrealized Losses) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value
Less than 12 months, fair value	$ 3,758.4	$ 7,850.3
12 months or longer fair value	3,943.4	10,615.2
Total fair value	7,701.8	18,465.5
Unrealized Losses
Less than 12 months, unrealized losses	10.8	57
12 months or longer unrealized losses	24.2	51.6
Total unrealized losses	35	108.6
U.S. Government
Fair Value
Less than 12 months, fair value		252.2
12 months or longer fair value		899.7
Total fair value		1,151.9
Unrealized Losses
Less than 12 months, unrealized losses		2.8
12 months or longer unrealized losses		2.3
Total unrealized losses		5.1
Obligations of States and Political Subdivisions
Fair Value
Less than 12 months, fair value	230.4	902.4
12 months or longer fair value	0	0
Total fair value	230.4	902.4
Unrealized Losses
Less than 12 months, unrealized losses	1	13.3
12 months or longer unrealized losses	0	0
Total unrealized losses	1	13.3
Government Sponsored Agency
Fair Value
Less than 12 months, fair value	2,578.6	5,405
12 months or longer fair value	2,862.3	7,818.4
Total fair value	5,440.9	13,223.4
Unrealized Losses
Less than 12 months, unrealized losses	6.8	35.6
12 months or longer unrealized losses	14.4	42.5
Total unrealized losses	21.2	78.1
Non-U.S. Government
Fair Value
Less than 12 months, fair value	26.5
12 months or longer fair value	0
Total fair value	26.5
Unrealized Losses
Less than 12 months, unrealized losses	0.1
12 months or longer unrealized losses	0
Total unrealized losses	0.1
Corporate Debt
Fair Value
Less than 12 months, fair value	69.1	279.3
12 months or longer fair value	76.1	492.7
Total fair value	145.2	772
Unrealized Losses
Less than 12 months, unrealized losses	1	1.1
12 months or longer unrealized losses	1.2	2.9
Total unrealized losses	2.2	4
Covered Bonds
Fair Value
Less than 12 months, fair value		138.7
12 months or longer fair value		25
Total fair value		163.7
Unrealized Losses
Less than 12 months, unrealized losses		0.7
12 months or longer unrealized losses		0.1
Total unrealized losses		0.8
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Fair Value
Less than 12 months, fair value	146.3	217.5
12 months or longer fair value	158.7	155.2
Total fair value	305	372.7
Unrealized Losses
Less than 12 months, unrealized losses	0.2	1
12 months or longer unrealized losses	0.1	0.1
Total unrealized losses	0.3	1.1
Other Asset-Backed
Fair Value
Less than 12 months, fair value	631.2	592.4
12 months or longer fair value	846.3	1,164.9
Total fair value	1,477.5	1,757.3
Unrealized Losses
Less than 12 months, unrealized losses	1	1.8
12 months or longer unrealized losses	8.5	3.5
Total unrealized losses	9.5	5.3
Commercial Mortgage-Backed
Fair Value
Less than 12 months, fair value	76.3	62.8
12 months or longer fair value	0	59.3
Total fair value	76.3	122.1
Unrealized Losses
Less than 12 months, unrealized losses	0.7	0.7
12 months or longer unrealized losses	0	0.2
Total unrealized losses	$ 0.7	$ 0.9

Securities (Narrative) (Details

Securities (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)investment	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)investment	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Number of securities in an unrealized loss position | investment	475		475
Total fair value	$ 7,700,000,000		$ 7,700,000,000
Total unrealized losses	35,000,000		35,000,000
Provision for credit losses	500,000	$ (7,000,000)	127,500,000	$ (13,500,000)
Debt securities, held-to-maturity	16,754,000,000		16,754,000,000		$ 12,284,500,000
Debt Securities, held-to-maturity, unrealized loss position, fair value	88,700,000		88,700,000
Held to maturity securities, transferred from available for sale	0	160,800,000	301,500,000	160,800,000
Gross proceeds from sale of securities	0	$ 177,300,000	689,200,000	$ 406,600,000
AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	2,491,900,000		2,491,900,000
A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	$ 6,172,500,000		$ 6,172,500,000
Percentage of debt securities, held-to-maturity, portfolio	0.37		0.37
NOT RATED
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	$ 1,168,900,000		$ 1,168,900,000
Government Sponsored Agency
Debt and Equity Securities, FV-NI [Line Items]
Total unrealized losses	21,200,000		21,200,000
Debt securities, held-to-maturity	3,400,000		3,400,000		4,100,000
Government Sponsored Agency | AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Government Sponsored Agency | A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Government Sponsored Agency | NOT RATED
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Other Asset-Backed
Debt and Equity Securities, FV-NI [Line Items]
Total unrealized losses	9,500,000		9,500,000
Debt securities, held-to-maturity	645,800,000		645,800,000		804,300,000
Other Asset-Backed | AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Other Asset-Backed | A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Other Asset-Backed | NOT RATED
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Corporate Debt
Debt and Equity Securities, FV-NI [Line Items]
Total unrealized losses	$ 2,200,000		$ 2,200,000
Percent of corporate debt portfolio	21.00%		21.00%
Provision for credit losses	$ 0		$ 0
Debt securities, held-to-maturity	530,300,000		530,300,000		405,100,000
Corporate Debt | AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	254,700,000		254,700,000
Corporate Debt | A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	272,000,000		272,000,000
Corporate Debt | NOT RATED
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Other
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	442,600,000		442,600,000		291,100,000
Other | AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Other | A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	0		0
Other | NOT RATED
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	442,600,000		442,600,000
U.S. Government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	$ 99,000,000		$ 99,000,000		$ 138,800,000
Percentage of debt securities, held-to-maturity, portfolio	0.41		0.41
U.S. Government | AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	$ 0		$ 0
Percentage of debt securities, held-to-maturity, portfolio	0.15		0.15
U.S. Government | A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	$ 0		$ 0
U.S. Government | NOT RATED
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, held-to-maturity	$ 0		$ 0
Percentage of debt securities, held-to-maturity, portfolio	0.07		0.07

Securities (Reconciliation of_2

Securities (Reconciliation of Amortized Cost to Fair Value of Securities Held to Maturity) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Total	$ 16,754	$ 12,284.5
Gross Unrealized Gains	82.9	45.7
Gross Unrealized Losses	90.4	80.9
Fair Value	16,746.5	12,249.3
U.S. Government
Schedule of Held-to-maturity Securities [Line Items]
Total	99	138.8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	99	138.8
Obligations of States and Political Subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Total	2.6	10.1
Gross Unrealized Gains	0.1	0.2
Gross Unrealized Losses	0	0
Fair Value	2.7	10.3
Government Sponsored Agency
Schedule of Held-to-maturity Securities [Line Items]
Total	3.4	4.1
Gross Unrealized Gains	0.3	0.2
Gross Unrealized Losses	0	0
Fair Value	3.7	4.3
Corporate Debt
Schedule of Held-to-maturity Securities [Line Items]
Total	530.3	405.1
Gross Unrealized Gains	5.5	1.4
Gross Unrealized Losses	0	0.3
Fair Value	535.8	406.2
Covered Bonds
Schedule of Held-to-maturity Securities [Line Items]
Total	3,361.7	3,006.7
Gross Unrealized Gains	25.4	16.1
Gross Unrealized Losses	1	2.4
Fair Value	3,386.1	3,020.4
Certificates of Deposit
Schedule of Held-to-maturity Securities [Line Items]
Total	726.3	262.9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	726.3	262.9
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Schedule of Held-to-maturity Securities [Line Items]
Total	3,390.5	3,285.4
Gross Unrealized Gains	42.8	21.7
Gross Unrealized Losses	0.3	2.1
Fair Value	3,433	3,305
Other Asset-Backed
Schedule of Held-to-maturity Securities [Line Items]
Total	645.8	804.3
Gross Unrealized Gains	0.7	0.7
Gross Unrealized Losses	0.2	0.3
Fair Value	646.3	804.7
Other
Schedule of Held-to-maturity Securities [Line Items]
Total	442.6	291.1
Gross Unrealized Gains	0	0.1
Gross Unrealized Losses	88.7	73.3
Fair Value	353.9	217.9
Non-U.S. Government
Schedule of Held-to-maturity Securities [Line Items]
Total	7,551.8	4,076
Gross Unrealized Gains	8.1	5.3
Gross Unrealized Losses	0.2	2.5
Fair Value	$ 7,559.7	$ 4,078.8

Securities (Credit Quality Indi

Securities (Credit Quality Indicators) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	$ 16,754	$ 12,284.5
AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	6,872.7
AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	2,491.9
A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	6,172.5
BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	48
NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	1,168.9
U.S. Government
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	99	138.8
U.S. Government | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	99
U.S. Government | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
U.S. Government | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
U.S. Government | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
U.S. Government | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Obligations of States and Political Subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	2.6	10.1
Obligations of States and Political Subdivisions | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Obligations of States and Political Subdivisions | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0.6
Obligations of States and Political Subdivisions | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0.7
Obligations of States and Political Subdivisions | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	1.3
Obligations of States and Political Subdivisions | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Government Sponsored Agency
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	3.4	4.1
Government Sponsored Agency | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	3.4
Government Sponsored Agency | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Government Sponsored Agency | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Government Sponsored Agency | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Government Sponsored Agency | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Non-U.S. Government
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	7,551.8	4,076
Non-U.S. Government | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	335.6
Non-U.S. Government | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	1,269.7
Non-U.S. Government | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	5,899.8
Non-U.S. Government | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	46.7
Non-U.S. Government | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Corporate Debt
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	530.3	405.1
Corporate Debt | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	3.6
Corporate Debt | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	254.7
Corporate Debt | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	272
Corporate Debt | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Corporate Debt | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Covered Bonds
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	3,361.7	3,006.7
Covered Bonds | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	3,361.7
Covered Bonds | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Covered Bonds | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Covered Bonds | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Covered Bonds | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Certificates of Deposit
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	726.3	262.9
Certificates of Deposit | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Certificates of Deposit | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Certificates of Deposit | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Certificates of Deposit | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Certificates of Deposit | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	726.3
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	3,390.5	3,285.4
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	2,423.6
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	966.9
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other Asset-Backed
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	645.8	804.3
Other Asset-Backed | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	645.8
Other Asset-Backed | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other Asset-Backed | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other Asset-Backed | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other Asset-Backed | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	442.6	$ 291.1
Other | AAA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other | AA
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other | A
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other | BBB
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	0
Other | NOT RATED
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	$ 442.6

Securities (Investment Security

Securities (Investment Security Gains and Losses) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Gross Realized Debt Securities Gains	$ 0		$ 0.1	$ 3.4	$ 1.6
Gross Realized Debt Securities Losses	0		(0.4)	(3.3)	(2.2)
Changes in Other-Than-Temporary Impairment Losses	0	$ (4.4)	(0.1)	0	(0.3)
Net Investment Security (Losses) Gains	$ 0		$ (0.4)	$ 0.1	$ (0.9)

Securities Sold Under Agreeme_3

Securities Sold Under Agreements to Repurchase (Repurchase Agreements Accounted for as Secured Borrowings) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Gross Amount of Recognized Liabilities for Repurchase Agreements in Note 21	$ 540.5	$ 693.9
OVERNIGHT AND CONTINUOUS
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Borrowings	269.8	489.7
Gross Amount of Recognized Liabilities for Repurchase Agreements in Note 21	269.8	489.7
Amounts related to agreements not included in Note 21	0	0
OVERNIGHT AND CONTINUOUS | U.S. Treasury and Agency Securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Borrowings	$ 269.8	$ 489.7

Loans and Leases (Loans and Lea

Loans and Leases (Loans and Leases) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	$ 32,766.3	$ 31,409.6
Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	338.7
COMMERCIAL
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	14,581.7	14,001.3
COMMERCIAL | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	9,524	9,091.1
COMMERCIAL | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	3,373.6	3,104.3
COMMERCIAL | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	1,441	1,576.3
COMMERCIAL | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	30.1	65.6
COMMERCIAL | Other
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	213	164
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	18,184.6	17,408.3
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	11,893	11,071.4
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	5,928.3	6,095
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	338.7	174.8
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
TOTAL LOANS AND LEASES	$ 24.6	$ 67.1

Loans and Leases (Narrative) (D

Loans and Leases (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)loan	Mar. 31, 2019loan	Sep. 30, 2020USD ($)loancontract	Dec. 31, 2019USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 32,766,300,000		$ 32,766,300,000	$ 31,409,600,000
Other U.S. loans and non-U.S. loans, short duration advances	1,300,000,000		1,300,000,000	1,100,000,000
Demand deposits	11,600,000		11,600,000	90,400,000
Financing receivable, nonaccrual troubled debt restructuring	67,500,000		67,500,000	54,900,000
Financing receivable, recorded investment	33,000,000		33,000,000	27,700,000	$ 1,700,000	$ 1,600,000
Financing receivable, troubled debt restructuring, commitment to lend	11,000,000		11,000,000	8,200,000
Foreclosed real estate properties, carrying value	900,000		900,000	3,200,000
Loans in process of foreclosure	11,700,000		$ 11,700,000
CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, modifications, number of contracts paid off | contract			31
Financing receivable, non-TDR modifications, recorded investment paid off			$ 34,300,000
Paycheck Protection Program
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 215,300,000		215,300,000
Loan processing fee			$ 2,600,000
Number of loans approved for forgiveness | loan	0		0
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, troubled debt restructuring, subsequent default, number of contracts | loan	0	3	0
Lease Agreements
Accounts, Notes, Loans and Financing Receivable [Line Items]
Held for sale	$ 18,600,000		$ 18,600,000	53,600,000
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Held for sale	0		0	0
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 18,184,600,000		$ 18,184,600,000	17,408,300,000
Personal | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral required on Residential real estate loan, lower limit	65.00%		65.00%
Collateral required on Residential real estate loan, upper limit	80.00%		80.00%
Loans and leases	$ 5,928,300,000		$ 5,928,300,000	6,095,000,000
Personal | Home Equity Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Draw period for credit line products			10 years
Loans and leases	$ 351,800,000		$ 351,800,000	$ 448,500,000
Percentage of total equity credit lines	97.00%		97.00%	97.00%
COMMERCIAL
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 14,581,700,000		$ 14,581,700,000	$ 14,001,300,000
COMMERCIAL | Commercial and Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	9,524,000,000		9,524,000,000	$ 9,091,100,000
COMMERCIAL | Commercial and Institutional | Paycheck Protection Program
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 215,300,000		$ 215,300,000
Number of contracts | loan	1,127,000,000		1,127,000,000
Financing receivable, average balance per loan	$ 200,000		$ 200,000

Loans and Leases (Credit Qualit

Loans and Leases (Credit Quality Indicator At Amortized Cost By Origination Year) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 5,922.4
2019	4,025
2018	1,447.2
2017	1,218.9
2016	1,447.8
PRIOR	3,293.7
REVOLVING LOANS	15,041
REVOLVING LOANS CONVERTED TO TERM LOANS	370.3
Total Loans and Leases	32,766.3	$ 31,409.6
Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2020	21.4
2019	44.2
2018	11.9
2017	0.5
2016	0.5
PRIOR	10.2
REVOLVING LOANS	244.9
REVOLVING LOANS CONVERTED TO TERM LOANS	5.1
Total Loans and Leases	338.7
Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	8.6
2019	21.5
2018	0
2017	0
2016	0
PRIOR	1.8
REVOLVING LOANS	28.2
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	60.1
Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	12.8
2019	22.7
2018	11.9
2017	0.5
2016	0.5
PRIOR	8.2
REVOLVING LOANS	216.7
REVOLVING LOANS CONVERTED TO TERM LOANS	5.1
Total Loans and Leases	278.4
Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	0.2
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	0.2
COMMERCIAL
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,980.3
2019	2,344.3
2018	1,037.3
2017	794
2016	844.3
PRIOR	1,301.1
REVOLVING LOANS	5,203.9
REVOLVING LOANS CONVERTED TO TERM LOANS	76.5
Total Loans and Leases	14,581.7	14,001.3
COMMERCIAL | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
2020	895.9
2019	1,285.8
2018	626.9
2017	600.2
2016	639.3
PRIOR	666.1
REVOLVING LOANS	4,757.7
REVOLVING LOANS CONVERTED TO TERM LOANS	52.1
Total Loans and Leases	9,524	9,091.1
COMMERCIAL | Commercial and Institutional | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	245.2
2019	571.6
2018	208.2
2017	142.8
2016	457.8
PRIOR	465.2
REVOLVING LOANS	3,286.6
REVOLVING LOANS CONVERTED TO TERM LOANS	2
Total Loans and Leases	5,379.4
COMMERCIAL | Commercial and Institutional | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	614
2019	579.5
2018	379.7
2017	428.4
2016	143
PRIOR	180.4
REVOLVING LOANS	1,346.4
REVOLVING LOANS CONVERTED TO TERM LOANS	50.1
Total Loans and Leases	3,721.5
COMMERCIAL | Commercial and Institutional | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	36.7
2019	134.7
2018	39
2017	29
2016	38.5
PRIOR	20.5
REVOLVING LOANS	124.7
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	423.1
COMMERCIAL | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	820.4
2019	1,018.9
2018	398.4
2017	183.1
2016	205
PRIOR	526.3
REVOLVING LOANS	198.9
REVOLVING LOANS CONVERTED TO TERM LOANS	22.6
Total Loans and Leases	3,373.6	3,104.3
COMMERCIAL | Commercial Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	359.5
2019	205.7
2018	71.8
2017	40.5
2016	24.9
PRIOR	113.4
REVOLVING LOANS	126.5
REVOLVING LOANS CONVERTED TO TERM LOANS	8.9
Total Loans and Leases	951.2
COMMERCIAL | Commercial Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	453.4
2019	758
2018	294.1
2017	110.6
2016	178.5
PRIOR	383.9
REVOLVING LOANS	72.4
REVOLVING LOANS CONVERTED TO TERM LOANS	13.7
Total Loans and Leases	2,264.6
COMMERCIAL | Commercial Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	7.5
2019	55.2
2018	32.5
2017	32
2016	1.6
PRIOR	29
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	157.8
COMMERCIAL | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,051
2019	39.6
2018	12
2017	10.7
2016	0
PRIOR	78.6
REVOLVING LOANS	247.3
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8
Total Loans and Leases	1,441	1,576.3
COMMERCIAL | Non-U.S. | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	790.8
2019	15.9
2018	10
2017	10.7
2016	0
PRIOR	0
REVOLVING LOANS	32.2
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	859.6
COMMERCIAL | Non-U.S. | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	259.5
2019	0.6
2018	2
2017	0
2016	0
PRIOR	78.6
REVOLVING LOANS	37.2
REVOLVING LOANS CONVERTED TO TERM LOANS	1.8
Total Loans and Leases	379.7
COMMERCIAL | Non-U.S. | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0.7
2019	23.1
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	177.9
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	201.7
COMMERCIAL | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	30.1
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	30.1	65.6
COMMERCIAL | Lease Financing, net | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	18.5
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	18.5
COMMERCIAL | Lease Financing, net | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	11.6
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	11.6
COMMERCIAL | Lease Financing, net | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	0
COMMERCIAL | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	213
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	213	164
COMMERCIAL | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	97.7
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	97.7
COMMERCIAL | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	115.3
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	115.3
COMMERCIAL | Other | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	0
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,942.1
2019	1,680.7
2018	409.9
2017	424.9
2016	603.5
PRIOR	1,992.6
REVOLVING LOANS	9,837.1
REVOLVING LOANS CONVERTED TO TERM LOANS	293.8
Total Loans and Leases	18,184.6	17,408.3
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
2020	940.3
2019	888.4
2018	208.8
2017	130.8
2016	112.3
PRIOR	231.1
REVOLVING LOANS	9,101.5
REVOLVING LOANS CONVERTED TO TERM LOANS	279.8
Total Loans and Leases	11,893	11,071.4
Personal | Private Client | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	466.3
2019	394.3
2018	56.8
2017	67.6
2016	34.2
PRIOR	150.2
REVOLVING LOANS	5,087.1
REVOLVING LOANS CONVERTED TO TERM LOANS	126.1
Total Loans and Leases	6,382.6
Personal | Private Client | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	468.4
2019	493.6
2018	129.6
2017	60
2016	78.1
PRIOR	80.9
REVOLVING LOANS	3,952.3
REVOLVING LOANS CONVERTED TO TERM LOANS	145.7
Total Loans and Leases	5,408.6
Personal | Private Client | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5.6
2019	0.5
2018	22.4
2017	3.2
2016	0
PRIOR	0
REVOLVING LOANS	62.1
REVOLVING LOANS CONVERTED TO TERM LOANS	8
Total Loans and Leases	101.8
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,955.8
2019	748.1
2018	189.2
2017	293.6
2016	490.7
PRIOR	1,751.3
REVOLVING LOANS	490.7
REVOLVING LOANS CONVERTED TO TERM LOANS	8.9
Total Loans and Leases	5,928.3	6,095
Personal | Residential Real Estate | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,322.9
2019	396.2
2018	60.9
2017	108.9
2016	254.2
PRIOR	738
REVOLVING LOANS	188.2
REVOLVING LOANS CONVERTED TO TERM LOANS	1.5
Total Loans and Leases	3,070.8
Personal | Residential Real Estate | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	619.8
2019	342.5
2018	126.6
2017	184.2
2016	233.8
PRIOR	904.6
REVOLVING LOANS	270.2
REVOLVING LOANS CONVERTED TO TERM LOANS	7.4
Total Loans and Leases	2,689.1
Personal | Residential Real Estate | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	13.1
2019	9.4
2018	1.7
2017	0.5
2016	2.7
PRIOR	108.7
REVOLVING LOANS	32.3
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	168.4
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	338.7	174.8
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	24.6
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	24.6	$ 67.1
Personal | Other | 1 to 3 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5.5
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	5.5
Personal | Other | 4 to 5 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	19.1
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	19.1
Personal | Other | 6 to 9 Category
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
PRIOR	0
REVOLVING LOANS	0
REVOLVING LOANS CONVERTED TO TERM LOANS	0
Total Loans and Leases	$ 0

Loans and Leases (Delinquency S

Loans and Leases (Delinquency Status) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	$ 32,572	$ 31,230.6
TOTAL ACCRUAL	32,668.3	31,326
NONACCRUAL	98	83.6
Total Loans and Leases	32,766.3	31,409.6
NONACCRUAL WITH NO ALLOWANCE	70.9	70.6
Other Real Estate Owned	0.9	3.2
Total Nonaccrual Assets	98.9	86.8
Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	338.7
30 – 59 DAYS PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	64.8	59.6
60 – 89 DAYS PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	22.9	28.4
90 DAYS OR MORE PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	8.6	7.4
COMMERCIAL
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	14,516	13,963.8
TOTAL ACCRUAL	14,547.6	13,990.1
NONACCRUAL	34.1	11.2
Total Loans and Leases	14,581.7	14,001.3
NONACCRUAL WITH NO ALLOWANCE	15.4	3.2
COMMERCIAL | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	9,470.9	9,068.3
TOTAL ACCRUAL	9,493.8	9,083.5
NONACCRUAL	30.2	7.6
Total Loans and Leases	9,524	9,091.1
NONACCRUAL WITH NO ALLOWANCE	11.5	0.8
COMMERCIAL | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	3,361	3,089.6
TOTAL ACCRUAL	3,369.7	3,100.7
NONACCRUAL	3.9	3.6
Total Loans and Leases	3,373.6	3,104.3
NONACCRUAL WITH NO ALLOWANCE	3.9	2.4
COMMERCIAL | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	1,441	1,576.3
TOTAL ACCRUAL	1,441	1,576.3
NONACCRUAL	0	0
Total Loans and Leases	1,441	1,576.3
NONACCRUAL WITH NO ALLOWANCE	0	0
COMMERCIAL | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	30.1	65.6
TOTAL ACCRUAL	30.1	65.6
NONACCRUAL	0	0
Total Loans and Leases	30.1	65.6
NONACCRUAL WITH NO ALLOWANCE	0	0
COMMERCIAL | Other
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	213	164
TOTAL ACCRUAL	213	164
NONACCRUAL	0	0
Total Loans and Leases	213	164
NONACCRUAL WITH NO ALLOWANCE	0	0
COMMERCIAL | 30 – 59 DAYS PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	22.5	6.4
COMMERCIAL | 30 – 59 DAYS PAST DUE | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	21.9	4.1
COMMERCIAL | 30 – 59 DAYS PAST DUE | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0.6	2.3
COMMERCIAL | 30 – 59 DAYS PAST DUE | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 30 – 59 DAYS PAST DUE | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 30 – 59 DAYS PAST DUE | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 60 – 89 DAYS PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	8.3	14
COMMERCIAL | 60 – 89 DAYS PAST DUE | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0.2	9.9
COMMERCIAL | 60 – 89 DAYS PAST DUE | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	8.1	4.1
COMMERCIAL | 60 – 89 DAYS PAST DUE | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 60 – 89 DAYS PAST DUE | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 60 – 89 DAYS PAST DUE | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 90 DAYS OR MORE PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0.8	5.9
COMMERCIAL | 90 DAYS OR MORE PAST DUE | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0.8	1.2
COMMERCIAL | 90 DAYS OR MORE PAST DUE | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	4.7
COMMERCIAL | 90 DAYS OR MORE PAST DUE | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 90 DAYS OR MORE PAST DUE | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
COMMERCIAL | 90 DAYS OR MORE PAST DUE | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	18,056	17,266.8
TOTAL ACCRUAL	18,120.7	17,335.9
NONACCRUAL	63.9	72.4
Total Loans and Leases	18,184.6	17,408.3
NONACCRUAL WITH NO ALLOWANCE	55.5	67.4
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	11,832.8	11,027.9
TOTAL ACCRUAL	11,893	11,070.9
NONACCRUAL	0	0.5
Total Loans and Leases	11,893	11,071.4
NONACCRUAL WITH NO ALLOWANCE	0	0.5
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	5,859.9	5,997.7
TOTAL ACCRUAL	5,864.4	6,023.6
NONACCRUAL	63.9	71.4
Total Loans and Leases	5,928.3	6,095
NONACCRUAL WITH NO ALLOWANCE	55.5	66.4
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	338.7	174.1
TOTAL ACCRUAL	338.7	174.3
NONACCRUAL	0	0.5
Total Loans and Leases	338.7	174.8
NONACCRUAL WITH NO ALLOWANCE	0	0.5
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
CURRENT	24.6	67.1
TOTAL ACCRUAL	24.6	67.1
NONACCRUAL	0	0
Total Loans and Leases	24.6	67.1
NONACCRUAL WITH NO ALLOWANCE	0	0
Personal | 30 – 59 DAYS PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	42.3	53.2
Personal | 30 – 59 DAYS PAST DUE | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	39.4	33.2
Personal | 30 – 59 DAYS PAST DUE | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	2.9	19.8
Personal | 30 – 59 DAYS PAST DUE | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0.2
Personal | 30 – 59 DAYS PAST DUE | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
Personal | 60 – 89 DAYS PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	14.6	14.4
Personal | 60 – 89 DAYS PAST DUE | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	13.3	9.5
Personal | 60 – 89 DAYS PAST DUE | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	1.3	4.9
Personal | 60 – 89 DAYS PAST DUE | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
Personal | 60 – 89 DAYS PAST DUE | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
Personal | 90 DAYS OR MORE PAST DUE
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	7.8	1.5
Personal | 90 DAYS OR MORE PAST DUE | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	7.5	0.3
Personal | 90 DAYS OR MORE PAST DUE | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0.3	1.2
Personal | 90 DAYS OR MORE PAST DUE | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	0	0
Personal | 90 DAYS OR MORE PAST DUE | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past Due	$ 0	$ 0

Loans and Leases (Troubled Debt

Loans and Leases (Troubled Debt Restructurings) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)contract	Sep. 30, 2019USD ($)contract	Sep. 30, 2020USD ($)contract	Sep. 30, 2019USD ($)contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	11	5	19	34
RECORDED INVESTMENT	$ 18.4	$ 3.1	$ 43.6	$ 28.2
UNPAID PRINCIPAL BALANCE	$ 18.5	$ 3.1	$ 44.2	$ 29.6
COMMERCIAL
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	0	3	3
RECORDED INVESTMENT	$ 1	$ 0	$ 25.3	$ 7.6
UNPAID PRINCIPAL BALANCE	$ 1	$ 0	$ 25.5	$ 8.8
COMMERCIAL | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	0	3	1
RECORDED INVESTMENT	$ 1	$ 0	$ 25.3	$ 7.6
UNPAID PRINCIPAL BALANCE	$ 1	$ 0	$ 25.5	$ 8.8
COMMERCIAL | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract		0		2
RECORDED INVESTMENT		$ 0		$ 0
UNPAID PRINCIPAL BALANCE		$ 0		$ 0
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	10	5	16	31
RECORDED INVESTMENT	$ 17.4	$ 3.1	$ 18.3	$ 20.6
UNPAID PRINCIPAL BALANCE	$ 17.5	$ 3.1	$ 18.7	$ 20.8
Personal | Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	10	5	16	31
RECORDED INVESTMENT	$ 17.4	$ 3.1	$ 18.3	$ 20.6
UNPAID PRINCIPAL BALANCE	$ 17.5	$ 3.1	$ 18.7	$ 20.8

Loans and Leases (COVID-19 Loan

Loans and Leases (COVID-19 Loan Modifications Not Considered TDRS) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020contract	Sep. 30, 2019contract	Sep. 30, 2020USD ($)contract	Sep. 30, 2019contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	11	5	19	34
CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			70,000,000
RECORDED INVESTMENT			$ 105
UNPAID PRINCIPAL BALANCE			0.6
DEFERRED INTEREST AMOUNT			$ 0.9
CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			585,000,000
RECORDED INVESTMENT			$ 1,034.3
UNPAID PRINCIPAL BALANCE			10.7
DEFERRED INTEREST AMOUNT			$ 7.9
COMMERCIAL
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	0	3	3
COMMERCIAL | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			15,000,000
RECORDED INVESTMENT			$ 80.5
UNPAID PRINCIPAL BALANCE			0.3
DEFERRED INTEREST AMOUNT			$ 0.5
COMMERCIAL | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			205,000,000
RECORDED INVESTMENT			$ 671.9
UNPAID PRINCIPAL BALANCE			7.9
DEFERRED INTEREST AMOUNT			$ 4.8
COMMERCIAL | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	0	3	1
COMMERCIAL | Commercial and Institutional | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			13,000,000
RECORDED INVESTMENT			$ 73.2
UNPAID PRINCIPAL BALANCE			0.3
DEFERRED INTEREST AMOUNT			$ 0.5
COMMERCIAL | Commercial and Institutional | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			101,000,000
RECORDED INVESTMENT			$ 199.7
UNPAID PRINCIPAL BALANCE			5
DEFERRED INTEREST AMOUNT			$ 1.5
COMMERCIAL | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract		0		2
COMMERCIAL | Commercial Real Estate | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			2,000,000
RECORDED INVESTMENT			$ 7.3
UNPAID PRINCIPAL BALANCE			0
DEFERRED INTEREST AMOUNT			$ 0
COMMERCIAL | Commercial Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			104,000,000
RECORDED INVESTMENT			$ 472.2
UNPAID PRINCIPAL BALANCE			2.9
DEFERRED INTEREST AMOUNT			$ 3.3
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	10	5	16	31
Personal | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			55,000,000
RECORDED INVESTMENT			$ 24.5
UNPAID PRINCIPAL BALANCE			0.3
DEFERRED INTEREST AMOUNT			$ 0.4
Personal | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			380,000,000
RECORDED INVESTMENT			$ 362.4
UNPAID PRINCIPAL BALANCE			2.8
DEFERRED INTEREST AMOUNT			$ 3.1
Personal | Private Client | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			2,000,000
RECORDED INVESTMENT			$ 5.2
UNPAID PRINCIPAL BALANCE			0
DEFERRED INTEREST AMOUNT			$ 0.1
Personal | Private Client | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			34,000,000
RECORDED INVESTMENT			$ 177.6
UNPAID PRINCIPAL BALANCE			2.3
DEFERRED INTEREST AMOUNT			$ 1.1
Personal | Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	10	5	16	31
Personal | Residential Real Estate | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			53,000,000
RECORDED INVESTMENT			$ 19.3
UNPAID PRINCIPAL BALANCE			0.3
DEFERRED INTEREST AMOUNT			$ 0.3
Personal | Residential Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			346,000,000
RECORDED INVESTMENT			$ 184.8
UNPAID PRINCIPAL BALANCE			0.5
DEFERRED INTEREST AMOUNT			$ 2

Allowance for Credit Losses (Na

Allowance for Credit Losses (Narrative) (Details) - USD ($)	Jan. 01, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Allowance for credit loss		$ 215,400,000		$ 105,700,000	$ 215,400,000	$ 105,700,000	$ 210,200,000	$ 104,500,000	$ 110,800,000		$ 112,600,000
Stockholders equity		(11,579,100,000)	$ (10,879,700,000)	(10,811,300,000)	(11,579,100,000)	(10,811,300,000)	(11,382,200,000)	(11,091,000,000)	(10,805,500,000)	$ (10,616,200,000)	(10,508,300,000)
Credit loss expense (reversal) and available-for-sale, allowance for credit loss		500,000		(7,000,000)	127,500,000	(13,500,000)
Net (charge-offs) recoveries		400,000		600,000	$ 2,300,000	3,000,000
Time period used for projecting future conditions to estimate credit losses					2 years
Interest income that would have been recorded for nonperforming loans				1,800,000		5,700,000
Financing receivable accrued interest income		1,100,000			$ 3,500,000
Other-than-temporary impairment loss, debt securities, portion recognized in earnings		0	4,400,000	100,000	0	300,000
Other financial assets, allowance for credit loss		700,000			700,000		1,300,000	0
Other Financial Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable accrued interest income		0		0	0	0
Cumulative Effect Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss	$ 13,700,000							(2,200,000)
Stockholders equity								10,100,000
Other financial assets, allowance for credit loss								400,000
Retained Earnings
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders equity		$ (12,118,300,000)	$ (11,828,100,000)	$ (11,441,200,000)	$ (12,118,300,000)	$ (11,441,200,000)	$ (11,988,400,000)	(11,656,700,000)	$ (11,225,500,000)	$ (10,972,900,000)	$ (10,776,800,000)
Retained Earnings | Cumulative Effect Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders equity	$ 10,100,000							$ 10,100,000

Allowance for Credit Losses (Ch

Allowance for Credit Losses (Changes in Allowance for Credit Losses) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
LOANS AND LEASES
Balance at Beginning of Period	$ 210,200,000	$ 110,800,000	$ 104,500,000	$ 112,600,000
Charge-Offs	(800,000)	(1,100,000)	(3,000,000)	(2,700,000)
Recoveries	1,200,000	1,700,000	5,300,000	5,700,000
Net (Charge-Offs) Recoveries	400,000	600,000	2,300,000	3,000,000
Provision for Credit Losses	4,800,000	(5,700,000)	110,800,000	(9,900,000)
Balance at End of Period	215,400,000	105,700,000	215,400,000	105,700,000
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period	49,000,000	23,300,000	19,900,000	25,600,000
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net (Charge-Offs) Recoveries	0	0	0	0
Provision for Credit Losses	(4,100,000)	(1,300,000)	16,100,000	(3,600,000)
Balance at End of Period	44,900,000	22,000,000	44,900,000	22,000,000
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	6,500,000		0
Charge-Offs	0		0
Recoveries	0		0
Net (Charge-Offs) Recoveries	0		0
Provision for Credit Losses	400,000		300,000
Balance at End of Period	6,900,000		6,900,000
OTHER FINANCIAL ASSETS
Balance at Beginning of Period	1,300,000		0
Charge-Offs	0		0
Recoveries	0		0
Net (Charge-Offs) Recoveries	0		0
Provision for Credit Losses	(600,000)		300,000
Balance at End of Period	700,000		700,000
TOTAL
Balance at Beginning of Period	267,000,000	134,100,000	124,400,000	138,200,000
Charge-Offs	(800,000)	(1,100,000)	(3,000,000)	(2,700,000)
Recoveries	1,200,000	1,700,000	5,300,000	5,700,000
Net (Charge-Offs) Recoveries			2,300,000	3,000,000
Provision for Credit Losses	500,000	(7,000,000)	127,500,000	(13,500,000)
Balance at End of Period	267,900,000	$ 127,700,000	267,900,000	$ 127,700,000
Corporate Debt
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	500,000		0
Provision for Credit Losses	200,000		(100,000)
Balance at End of Period	700,000		700,000
TOTAL
Provision for Credit Losses	$ 0		0
Cumulative Effect Adjustment
LOANS AND LEASES
Balance at Beginning of Period			(2,200,000)
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			8,900,000
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period			6,600,000
OTHER FINANCIAL ASSETS
Balance at Beginning of Period			400,000
TOTAL
Balance at Beginning of Period			13,700,000
Cumulative Effect Adjustment | Corporate Debt
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period			800,000
Adjusted Balance
LOANS AND LEASES
Balance at Beginning of Period			102,300,000
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			28,800,000
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period			6,600,000
OTHER FINANCIAL ASSETS
Balance at Beginning of Period			400,000
TOTAL
Balance at Beginning of Period			138,100,000
Adjusted Balance | Corporate Debt
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period			$ 800,000

Allowance for Credit Losses (Ac

Allowance for Credit Losses (Accrued Interest) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Receivables [Abstract]
Loans and Leases	$ 54.2	$ 84.5
Debt Securities
Held to Maturity	71.7	82.3
Available for Sale	101	119
Other Financial Assets	$ 1.7	$ 14.7

Allowance for Credit Losses (_2

Allowance for Credit Losses (Accrued Interest Reversed Through Income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable accrued interest income	$ 1.1	$ 3.5
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable accrued interest income	0.5	1.5
Personal
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable accrued interest income	$ 0.6	$ 2

Allowance for Credit Losses (_3

Allowance for Credit Losses (Changes in Allowance for Credit Losses Related to Loan and Leases) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
LOANS AND LEASES
Balance at Beginning of Period	$ 210.2	$ 110.8	$ 104.5	$ 112.6
Charge-Offs	(0.8)	(1.1)	(3)	(2.7)
Recoveries	1.2	1.7	5.3	5.7
Net (Charge-Offs) Recoveries	0.4	0.6	2.3	3
Provision for Credit Losses	4.8	(5.7)	110.8	(9.9)
Balance at End of Period	215.4	105.7	215.4	105.7
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period	49	23.3	19.9	25.6
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net (Charge-Offs) Recoveries	0	0	0	0
Provision for Credit Losses	(4.1)	(1.3)	16.1	(3.6)
Balance at End of Period	44.9	22	44.9	22
COMMERCIAL
LOANS AND LEASES
Balance at Beginning of Period	162.8	59.9	58.1	57.6
Charge-Offs	0	0	(0.1)	(0.1)
Recoveries	0.2	0	2.2	0.7
Net (Charge-Offs) Recoveries	0.2	0	2.1	0.6
Provision for Credit Losses	(15.4)	(1.3)	93.3	0.4
Balance at End of Period	147.6	58.6	147.6	58.6
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period	46.1	18.5	15.8	21.1
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net (Charge-Offs) Recoveries	0	0	0	0
Provision for Credit Losses	(6)	(0.7)	12.4	(3.3)
Balance at End of Period	40.1	17.8	40.1	17.8
PERSONAL
LOANS AND LEASES
Balance at Beginning of Period	47.4	50.9	46.4	55
Charge-Offs	(0.8)	(1.1)	(2.9)	(2.6)
Recoveries	1	1.7	3.1	5
Net (Charge-Offs) Recoveries	0.2	0.6	0.2	2.4
Provision for Credit Losses	20.2	(4.4)	17.5	(10.3)
Balance at End of Period	67.8	47.1	67.8	47.1
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period	2.9	4.8	4.1	4.5
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net (Charge-Offs) Recoveries	0	0	0	0
Provision for Credit Losses	1.9	(0.6)	3.7	(0.3)
Balance at End of Period	$ 4.8	$ 4.2	4.8	$ 4.2
Cumulative Effect Adjustment
LOANS AND LEASES
Balance at Beginning of Period			(2.2)
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			8.9
Cumulative Effect Adjustment | COMMERCIAL
LOANS AND LEASES
Balance at Beginning of Period			(5.9)
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			11.9
Cumulative Effect Adjustment | PERSONAL
LOANS AND LEASES
Balance at Beginning of Period			3.7
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			(3)
Adjusted Balance
LOANS AND LEASES
Balance at Beginning of Period			102.3
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			28.8
Adjusted Balance | COMMERCIAL
LOANS AND LEASES
Balance at Beginning of Period			52.2
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			27.7
Adjusted Balance | PERSONAL
LOANS AND LEASES
Balance at Beginning of Period			50.1
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period			$ 1.1

Allowance for Credit Losses (Re

Allowance for Credit Losses (Recorded Investments in Loans and Leases) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Loans and Leases
Evaluated on an Individual Level	$ 98		$ 92.2
Evaluated on a Collective Level	32,668.3		31,317.4
TOTAL LOANS AND LEASES	32,766.3		31,409.6
Allowance for Credit Losses on Credit Exposures
Evaluated on an Individual Level	6		5
Evaluated on a Collective Level	209.4		99.5
Allowance Assigned to Loans and Leases	215.4	$ 210.2	104.5	$ 105.7	$ 110.8	$ 112.6
Allowance for Undrawn Loan Commitments and Standby Letters of Credit
Evaluated on an Individual Level	2.2		1.9
Evaluated on a Collective Level	42.7		18
Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit	44.9	49	19.9	22	23.3	25.6
Total Allowance Assigned to Loans and Leases and Undrawn Loan Commitments and Standby Letters of Credit	260.3		124.4
COMMERCIAL
Loans and Leases
Evaluated on an Individual Level	34.1		10.4
Evaluated on a Collective Level	14,547.6		13,990.9
TOTAL LOANS AND LEASES	14,581.7
Allowance for Credit Losses on Credit Exposures
Evaluated on an Individual Level	5.6		3.4
Evaluated on a Collective Level	142		54.7
Allowance Assigned to Loans and Leases	147.6		58.1
Allowance for Undrawn Loan Commitments and Standby Letters of Credit
Evaluated on an Individual Level	2.2		1.9
Evaluated on a Collective Level	37.9		13.9
Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit	40.1		15.8
Total Allowance Assigned to Loans and Leases and Undrawn Loan Commitments and Standby Letters of Credit	187.7		73.9
Personal
Loans and Leases
Evaluated on an Individual Level	63.9		81.8
Evaluated on a Collective Level	18,120.7		17,326.5
TOTAL LOANS AND LEASES	18,184.6
Allowance for Credit Losses on Credit Exposures
Evaluated on an Individual Level	0.4		1.6
Evaluated on a Collective Level	67.4		44.8
Allowance Assigned to Loans and Leases	67.8		46.4
Allowance for Undrawn Loan Commitments and Standby Letters of Credit
Evaluated on an Individual Level	0		0
Evaluated on a Collective Level	4.8		4.1
Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit	4.8		4.1
Total Allowance Assigned to Loans and Leases and Undrawn Loan Commitments and Standby Letters of Credit	72.6		50.5
COMMERCIAL
Loans and Leases
TOTAL LOANS AND LEASES	14,581.7		14,001.3
Allowance for Credit Losses on Credit Exposures
Allowance Assigned to Loans and Leases	147.6	162.8	58.1	58.6	59.9	57.6
Allowance for Undrawn Loan Commitments and Standby Letters of Credit
Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit	40.1	46.1	15.8	17.8	18.5	21.1
Personal
Loans and Leases
TOTAL LOANS AND LEASES	18,184.6		17,408.3
Allowance for Credit Losses on Credit Exposures
Allowance Assigned to Loans and Leases	67.8	47.4	46.4	47.1	50.9	55
Allowance for Undrawn Loan Commitments and Standby Letters of Credit
Allowance Assigned to Undrawn Loan Commitments and Standby Letters of Credit	$ 4.8	$ 2.9	$ 4.1	$ 4.2	$ 4.8	$ 4.5

Allowance for Credit Losses (_4

Allowance for Credit Losses (Changes in The Allowance for Credit Losses Related to Debt Securities Held to Maturity) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	$ 6.5	$ 0
Provision for Credit Losses	0.4	0.3
Balance at End of Period	6.9	6.9
Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		6.6
Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		6.6
CORPORATE DEBT
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	0.5	0
Provision for Credit Losses	0.2	(0.1)
Balance at End of Period	0.7	0.7
CORPORATE DEBT | Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0.8
CORPORATE DEBT | Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0.8
Non-U.S. Government
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	0.4	0
Provision for Credit Losses	0	0.1
Balance at End of Period	0.4	0.4
Non-U.S. Government | Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0.3
Non-U.S. Government | Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0.3
SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	0.7	0
Provision for Credit Losses	(0.1)	(0.3)
Balance at End of Period	0.6	0.6
SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS | Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0.9
SUB-SOVEREIGN, SUPERNATIONAL, AND NON-U.S. AGENCY BONDS | Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0.9
CERTIFICATE OF DEPOSITS
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	0	0
Provision for Credit Losses	0.2	0.2
Balance at End of Period	0.2	0.2
CERTIFICATE OF DEPOSITS | Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0
CERTIFICATE OF DEPOSITS | Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0
COVERED BONDS
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	0	0
Provision for Credit Losses	0.1	0.1
Balance at End of Period	0.1	0.1
COVERED BONDS | Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0
COVERED BONDS | Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		0
OTHER
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period	4.9	0
Provision for Credit Losses	0	0.3
Balance at End of Period	$ 4.9	4.9
OTHER | Cumulative Effect Adjustment
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		4.6
OTHER | Adjusted Balance
DEBT SECURITIES HELD TO MATURITY
Balance at Beginning of Period		$ 4.6

Pledged Assets (Type of Pledged

Pledged Assets (Type of Pledged Assets) (Details) - USD ($) $ in Billions	Sep. 30, 2020	Dec. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Pledged Assets	$ 43.4	$ 42.1
Obligations of States and Political Subdivisions
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Pledged Assets	1.6	1
Government Sponsored Agency and Other Securities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Pledged Assets	30	33.4
Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Pledged Assets	$ 11.8	$ 7.7

Pledged Assets (Narrative) (Det

Pledged Assets (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security owned and pledged as collateral, fair value		$ 43,400,000,000		$ 42,100,000,000
Securities eligible to be repledged or sold		268,600,000		487,200,000
Collateral securities repledged, delivered, or used		0		0
Average deposits maintained to meet Federal Reserve Bank reserve requirements	$ 1,600,000,000	500,000,000	$ 1,500,000,000
Collateral Requirements
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security owned and pledged as collateral, fair value		$ 7,600,000,000		$ 8,500,000,000

Pledged Assets (Fair Value Of A

Pledged Assets (Fair Value Of Available For Sale Debt Securities Included In Pledged Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Debt Securities Available for Sale	$ 43,400	$ 42,100
SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE
Financial Instruments Owned and Pledged as Collateral [Line Items]
Debt Securities Available for Sale	268.6	487.1
DERIVATIVE CONTRACTS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Debt Securities Available for Sale	$ 30	$ 14.4

Pledged Assets (Accepted Collat

Pledged Assets (Accepted Collateral) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fair value of accepted collateral	$ 1,533.4	$ 707.8
Derivative contracts
Financial Instruments Owned and Pledged as Collateral [Line Items]
Fair value of accepted collateral	$ 30.6	$ 16.8

Goodwill and Other Intangible_2

Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 696.8
Foreign Exchange Rates	1.2
Goodwill, Ending Balance	698
CORPORATE & INSTITUTIONAL SERVICES
Goodwill [Roll Forward]
Goodwill, Beginning Balance	625.7
Foreign Exchange Rates	1.2
Goodwill, Ending Balance	626.9
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	71.1
Foreign Exchange Rates	0
Goodwill, Ending Balance	$ 71.1

Goodwill and Other Intangible_3

Goodwill and Other Intangibles (Other Intangible Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Gross Carrying Amount	$ 214.3	$ 207.2
Less: Accumulated Amortization	101.7	86.6
Net Book Value	$ 112.6	$ 120.6

Goodwill and Other Intangible_4

Goodwill and Other Intangibles (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense related to other intangible assets			$ 12.6	$ 12.5
Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense related to other intangible assets	$ 4.3	$ 4.2	12.6	$ 12.5
Estimated future amortization expense for 2020	4.3		4.3
Estimated future amortization expense for 2021	14.7		14.7
Estimated future amortization expense for 2022	10.1		10.1
Estimated future amortization expense for 2023	9.8		9.8
Estimated future amortization expense for 2024	$ 9.7		$ 9.7

Reporting Segments (Results of

Reporting Segments (Results of Reporting Segments) (Details) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2020USD ($)segment	Sep. 30, 2019USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | segment							2
Noninterest Income
Trust, Investment and Other Servicing Fees	$ 1,003.8			$ 975.5			$ 2,968.9	$ 2,859.9
Foreign Exchange Trading Income	61.6			59.7			221.8	186.4
Other Noninterest Income	91.1			85			279.4	222
Total Noninterest Income	1,156.5			1,120.2			3,470.1	3,268.3
Net Interest Income	336.5			425.3			1,132.5	1,280.2
Revenue	1,493			1,545.5			4,602.6	4,548.5
Provision for Credit Losses	0.5			(7)			127.5	(13.5)
Noninterest Expense	1,094.7			1,036.3			3,197.2	3,071.2
Income before Income Taxes	397.8			516.2			1,277.9	1,490.8
Provision for Income Taxes	103.3			131.6			309.5	369.7
Net Income	$ 294.5	$ 313.3	$ 360.6	$ 384.6	$ 389.4	$ 347.1	$ 968.4	$ 1,121.1
Percentage of Consolidated Net Income	100.00%			100.00%			100.00%	100.00%
Average Assets	$ 140,925.4			$ 116,352.1			$ 134,645.2	$ 117,364.7
FTE adjustments	7.9			7.6			23.7	23.1
CORPORATE & INSTITUTIONAL SERVICES
Noninterest Income
Trust, Investment and Other Servicing Fees	584.9			559.9			1,725.5	1,644.5
Foreign Exchange Trading Income	58.4			55.5			211.8	172.5
Other Noninterest Income	56.7			53.6			167.5	141.8
Total Noninterest Income	700			669			2,104.8	1,958.8
Net Interest Income	139.9			229.9			516.6	694.3
Revenue	839.9			898.9			2,621.4	2,653.1
Provision for Credit Losses	(19.2)			4.8			35.3	1.3
Noninterest Expense	707.3			649.2			2,022.2	1,930.5
Income before Income Taxes	151.8			244.9			563.9	721.3
Provision for Income Taxes	38.7			59.9			129.9	171.8
Net Income	$ 113.1			$ 185			$ 434	$ 549.5
Percentage of Consolidated Net Income	39.00%			48.00%			45.00%	49.00%
Average Assets	$ 108,823			$ 85,982.2			$ 102,902.3	$ 87,664.1
WEALTH MANAGEMENT
Noninterest Income
Trust, Investment and Other Servicing Fees	418.9			415.6			1,243.4	1,215.4
Foreign Exchange Trading Income	3.2			4.2			10	13.9
Other Noninterest Income	39.7			38.1			122.9	95.1
Total Noninterest Income	461.8			457.9			1,376.3	1,324.4
Net Interest Income	196.6			195.4			615.9	585.9
Revenue	658.4			653.3			1,992.2	1,910.3
Provision for Credit Losses	19.7			(11.8)			92.2	(14.8)
Noninterest Expense	386.3			385.9			1,152.7	1,137.9
Income before Income Taxes	252.4			279.2			747.3	787.2
Provision for Income Taxes	66.2			73.6			187.9	202.3
Net Income	$ 186.2			$ 205.6			$ 559.4	$ 584.9
Percentage of Consolidated Net Income	63.00%			54.00%			58.00%	52.00%
Average Assets	$ 32,102.4			$ 30,369.9			$ 31,742.9	$ 29,700.6
TREASURY AND OTHER
Noninterest Income
Trust, Investment and Other Servicing Fees	0			0			0	0
Foreign Exchange Trading Income	0			0			0	0
Other Noninterest Income	(5.3)			(6.7)			(11)	(14.9)
Total Noninterest Income	(5.3)			(6.7)			(11)	(14.9)
Net Interest Income	0			0			0	0
Revenue	(5.3)			(6.7)			(11)	(14.9)
Provision for Credit Losses	0			0			0	0
Noninterest Expense	1.1			1.2			22.3	2.8
Income before Income Taxes	(6.4)			(7.9)			(33.3)	(17.7)
Provision for Income Taxes	(1.6)			(1.9)			(8.3)	(4.4)
Net Income	$ (4.8)			$ (6)			$ (25)	$ (13.3)
Percentage of Consolidated Net Income	(2.00%)			(2.00%)			(3.00%)	(1.00%)
Average Assets	$ 0			$ 0			$ 0	$ 0

Stockholders' Equity (Narrative

Stockholders' Equity (Narrative) (Details) - USD ($)	Jul. 21, 2020	Apr. 21, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Jul. 31, 2018
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)			10,000,000						10,000,000	10,000,000
Stockholders' equity			$ 11,579,100,000	$ 11,382,200,000	$ 10,879,700,000	$ 10,811,300,000	$ 10,805,500,000	$ 10,616,200,000	$ 11,579,100,000	$ 11,091,000,000	$ 10,508,300,000
Common stock dividends (in usd per share)			$ 0.70	$ 0.70	$ 0.70	$ 0.70	$ 0.60	$ 0.60
Stock repurchase, share-based compensation plan (in shares)			18,534						518,745
Stock repurchase, aggregate cost			$ 1,500,000	$ 200,000	$ 296,800,000	$ 307,200,000	$ 271,200,000	$ 257,400,000	$ 298,500,000
Average price paid per share for common stock repurchased (in usd per share)			$ 81.02						$ 91.49
Stock repurchase, shares (in shares)									3,262,621
Stock repurchase program, number of shares authorized to be repurchased (in shares)												25,000,000
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			5,000						5,000	5,000
Stockholders' equity			$ 493,500,000						$ 493,500,000	$ 493,500,000
Preferred stock, liquidation preference			$ 100,000						$ 100,000
Depository shares, liquidation preference per share (in dollars per share)			$ 1,000						$ 1,000
Preferred stock, annual dividend rate									4.60%
Preferred stock, dividend payment rate, variable rate									3.202%
Common stock dividends (in usd per share)	$ 2,300
Series E Preferred Stock
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			16,000						16,000	16,000
Percentage of ownership interest per each depository shares			0.10%						0.10%
Stockholders' equity			$ 391,400,000						$ 391,400,000	$ 391,400,000
Preferred stock, without par value (in dollars per share)			$ 0						$ 0
Preferred stock, liquidation preference			$ 25,000						$ 25,000
Depository shares, liquidation preference per share (in dollars per share)			$ 25						$ 25
Preferred stock, annual dividend rate									4.70%
Common stock dividends (in usd per share)		$ 293.75
Series D Preferred Stock, Depositary Shares
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			500,000						500,000
Preferred stock, shares issued (in shares)			500,000						500,000
Percentage of ownership interest per each depository shares			1.00%						1.00%
Series E Preferred Stock Depositary Shares
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			16,000,000						16,000,000
Preferred stock, shares issued (in shares)			16,000,000						16,000,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 11,382.2	$ 10,879.7	$ 11,091	$ 10,805.5	$ 10,616.2	$ 10,508.3	$ 11,091	$ 10,508.3
Net Change	54.1	325.4	239.7	68.8	185.5	108.4	619.2	362.7
Ending balance	11,579.1	11,382.2	10,879.7	10,811.3	10,805.5	10,616.2	11,579.1	10,811.3
TOTAL
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	370.4	45	(194.7)	(159.8)	(345.3)	(453.7)	(194.7)	(453.7)
Net Change	54.1	325.4	239.7	68.8	185.5	108.4
Ending balance	424.5	370.4	45	(91)	(159.8)	(345.3)	424.5	(91)
NET UNREALIZED GAINS (LOSSES) ON DEBT SECURITIES AVAILABLE FOR SALE
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	631.8		114	133.1		(114.9)	114	(114.9)
Net Change	33.5			57			551.3	305
Ending balance	665.3	631.8		190.1	133.1		665.3	190.1
NET UNREALIZED (LOSSES) GAINS ON CASH FLOW HEDGES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	0.3		(3.7)	4.5		4	(3.7)	4
Net Change	1.3			(2.4)			5.3	(1.9)
Ending balance	1.6	0.3		2.1	4.5		1.6	2.1
NET FOREIGN CURRENCY ADJUSTMENT
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	145.5		117.8	96.8		67.9	117.8	67.9
Net Change	1.8			9.9			29.5	38.8
Ending balance	147.3	145.5		106.7	96.8		147.3	106.7
NET PENSION AND OTHER POSTRETIREMENT BENEFIT ADJUSTMENTS
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(407.2)		$ (422.8)	(394.2)		$ (410.7)	(422.8)	(410.7)
Net Change	17.5			4.3			33.1	20.8
Ending balance	$ (389.7)	$ (407.2)		$ (389.9)	$ (394.2)		$ (389.7)	$ (389.9)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) (Details of Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
BEFORE TAX
Net Change	$ 46.1			$ 113.2			$ 811.7	$ 508.4
TAX EFFECT
Net Change	8			(44.4)			(192.5)	(145.7)
AFTER TAX
Net Change	54.1	$ 325.4	$ 239.7	68.8	$ 185.5	$ 108.4	619.2	362.7
Unrealized Gains (Losses) on Debt Securities Available for Sale
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	45.3			76.1			736.8	409
Reclassification Adjustment for (Gains) Losses Included in Net Income	0			0.3			(0.1)	0.6
Net Change	45.3			76.4			736.7	409.6
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	(11.8)			(19.4)			(185.4)	(104.6)
Reclassification Adjustment for (Gains) Losses Included in Net Income	0			0			0	0
Net Change	(11.8)			(19.4)			(185.4)	(104.6)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	33.5			56.7			551.4	304.4
Reclassification Adjustment for (Gains) Losses Included in Net Income	0			0.3			(0.1)	0.6
Net Change	33.5			57			551.3	305
Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(4.7)			(4)			(11.2)	(21.4)
Net Change	1.7			(3.2)			7.1	(2.6)
TAX EFFECT
Reclassification Adjustment for (Gains) Losses Included in Net Income	1.2			1			2.8	5.3
Net Change	(0.4)			0.8			(1.8)	0.7
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(3.5)			(3)			(8.4)	(16.1)
Net Change	1.3			(2.4)			5.3	(1.9)
Foreign Currency Adjustments
BEFORE TAX
Net Change	(24.1)			34.4			24	73.4
TAX EFFECT
Net Change	25.9			(24.5)			5.5	(34.6)
AFTER TAX
Net Change	1.8			9.9			29.5	38.8
Foreign Currency Translation Adjustments
BEFORE TAX
Net Change	92.1			(71.9)			53.1	(69.4)
TAX EFFECT
Net Change	(3.1)			2			(1)	3.3
AFTER TAX
Net Change	89			(69.9)			52.1	(66.1)
Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses)
BEFORE TAX
Net Change	1.2			(1.3)			0.7	(1.3)
TAX EFFECT
Net Change	(0.3)			0.3			(0.2)	0.3
AFTER TAX
Net Change	0.9			(1)			0.5	(1)
Net Investment Hedge Gains (Losses)
BEFORE TAX
Net Change	(117.4)			107.6			(29.8)	144.1
TAX EFFECT
Net Change	29.3			(26.8)			6.7	(38.2)
AFTER TAX
Net Change	(88.1)			80.8			(23.1)	105.9
Pension and Other Postretirement Benefit Adjustments
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	12.6			0			11.8	11.4
Net Change	23.2			5.6			43.9	28
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	(3.1)			0			(3)	(3.1)
Net Change	(5.7)			(1.3)			(10.8)	(7.2)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	9.5			0			8.8	8.3
Net Change	17.5			4.3			33.1	20.8
Amortization of Net Actuarial Loss
BEFORE TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	10.7			5.7			32.3	16.8
TAX EFFECT
Reclassification Adjustment for (Gains) Losses Included in Net Income	(2.6)			(1.3)			(7.8)	(4.1)
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	8.1			4.4			24.5	12.7
Amortization of Prior Service Cost
BEFORE TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.1)			(0.1)			(0.2)	(0.2)
TAX EFFECT
Reclassification Adjustment for (Gains) Losses Included in Net Income	0			0			0	0
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.1)			(0.1)			(0.2)	(0.2)
Foreign Exchange Contracts | Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	6.6			0.7			18.1	17.4
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	(1.6)			(0.2)			(4.5)	(4.3)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	5			0.5			13.6	13.1
Interest Rate Contracts | Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	(0.2)			0.1			0.2	1.4
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	0			0			(0.1)	(0.3)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	$ (0.2)			$ 0.1			$ 0.1	$ 1.1

Net Income Per Common Share C_3

Net Income Per Common Share Computations (Net Income Per Common Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic Net Income Per Common Share
Average Number of Common Shares Outstanding (in shares)	208,106,190			213,176,809			208,351,088	215,832,347
Net Income	$ 294.5	$ 313.3	$ 360.6	$ 384.6	$ 389.4	$ 347.1	$ 968.4	$ 1,121.1
Less: Dividends on Preferred Stock	16.2			17.4			51.5	40.6
Net Income Applicable to Common Stock	278.3			367.2			916.9	1,080.5
Less: Earnings Allocated to Participating Securities	3.3			4.5			10.6	12.6
Earnings Allocated to Common Shares Outstanding	$ 275			$ 362.7			$ 906.3	$ 1,067.9
Basic Net Income Per Common Share (in dollars per share)	$ 1.32			$ 1.70			$ 4.35	$ 4.95
Diluted Net Income Per Common Share
Average Number of Common Shares Outstanding (in shares)	208,106,190			213,176,809			208,351,088	215,832,347
Plus: Dilutive Effect of Share-based Compensation (in shares)	582,304			1,029,767			672,243	1,031,216
Diluted (in shares)	208,688,494			214,206,576			209,023,331	216,863,563
Earnings Allocated to Common and Potential Common Shares	$ 275			$ 362.7			$ 906.3	$ 1,067.9
Diluted Net Income Per Common Share (in dollars per share)	$ 1.32			$ 1.69			$ 4.34	$ 4.92
Common stock equivalents not included in the computation of diluted earnings per share because their inclusion would have been antidilutive (in shares)	0			0			0	0

Revenue from Contracts with C_3

Revenue from Contracts with Clients (Revenue Disaggregation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from contract with client	$ 1,003.8	$ 975.5	$ 2,968.9	$ 2,859.9
Foreign Exchange Trading Income	61.6	59.7	221.8	186.4
Treasury Management Fees	11.6	11.2	34	34.1
Security Commissions and Trading Income	26	29.1	100.9	75.8
Other Operating Income	53.5	45.1	144.4	113
Investment Security Gains (Losses), net	0	(0.4)	0.1	(0.9)
Total Other Noninterest Income	152.7	144.7	501.2	408.4
Total Noninterest Income	1,156.5	1,120.2	3,470.1	3,268.3
Custody and Fund Administration
Disaggregation of Revenue [Line Items]
Revenue from contract with client	416.4	414.8	1,231.7	1,219.7
Investment Management and Advisory
Disaggregation of Revenue [Line Items]
Revenue from contract with client	519.3	491.4	1,515.2	1,428.7
Securities Lending
Disaggregation of Revenue [Line Items]
Revenue from contract with client	19.8	20.1	70.7	64.9
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with client	$ 48.3	$ 49.2	$ 151.3	$ 146.6

Revenue from Contracts with C_4

Revenue from Contracts with Clients (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from contract with client	$ 1,003.8	$ 975.5	$ 2,968.9	$ 2,859.9
Security commissions and trading income	26	29.1	100.9	75.8
Other operating income	53.5	45.1	144.4	113
Securities Commissions and Trading Income
Disaggregation of Revenue [Line Items]
Revenue from contract with client	21.8	23.5	76.9	64.3
Other Operating Income
Disaggregation of Revenue [Line Items]
Revenue from contract with client	$ 10.8	$ 10.5	$ 31.6	$ 30.9

Revenue from Contracts with C_5

Revenue from Contracts with Clients (Contract Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 918.9	$ 903
Trust Fees Receivable, net
Disaggregation of Revenue [Line Items]
Total Client Receivables	805.7	801.9
Contract with customer, asset, allowance for credit loss	7.3	5.6
Other
Disaggregation of Revenue [Line Items]
Total Client Receivables	$ 113.2	$ 101.1

Net Interest Income (Net Intere

Net Interest Income (Net Interest Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest Income
Loans and Leases	$ 167.1	$ 291	$ 606.4	$ 889.8
Securities — Taxable	182.6	265.9	632.1	812.4
Securities - Non-Taxable	0.3	0.9	1.1	3.1
Interest-Bearing Due from and Deposits with Banks	2.7	18.6	20	55.7
Federal Reserve and Other Central Bank Deposits and Other	2.7	44.4	31.3	162.8
Total Interest Income	355.4	620.8	1,290.9	1,923.8
Interest Expense
Deposits	(3.5)	122	56.7	403.5
Federal Funds Purchased	0.1	2.4	2.1	22.8
Securities Sold Under Agreements to Repurchase	0	1.6	1	5.4
Other Borrowings	5	46	40.6	145.2
Senior Notes	19.1	19.6	57	54
Long-Term Debt	5.7	9.4	21.1	29.4
Floating Rate Capital Debt	0.4	2.1	3.6	6.4
Total Interest Expense	26.8	203.1	182.1	666.7
Net Interest Income	$ 328.6	$ 417.7	$ 1,108.8	$ 1,257.1

Pension and Postretirement He_3

Pension and Postretirement Health Care (Net Periodic Pension Expense (Benefit)) (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Amortization
Defined benefit plan, benefit obligation, increase (decrease) for plan amendment	$ 12,600,000
Defined benefit plan, benefit obligation, increase (decrease) for amortization period adjustment	$ 300,000	$ (97,500,000)	$ (87,600,000)	$ (285,800,000)	$ (262,600,000)
Pension Plan
Amortization
Contribution to pension plan				0	0
Supplemental Plan
Defined Benefit plan Net periodic benefit cost
Service Cost		1,200,000	1,100,000	3,400,000	3,100,000
Interest Cost		1,200,000	1,500,000	3,600,000	4,400,000
Amortization
Net Actuarial Loss (Gain)		1,700,000	1,400,000	5,300,000	4,200,000
Prior Service Cost		0	0	100,000	100,000
Net Periodic Pension Expense		4,100,000	4,000,000	12,400,000	11,800,000
Postretirement Health Care Plan
Defined Benefit plan Net periodic benefit cost
Interest Cost		200,000	300,000	600,000	900,000
Amortization
Net Actuarial Loss (Gain)		(100,000)	(200,000)	(500,000)	(800,000)
Prior Service Cost		(100,000)	0	(100,000)	0
Net Periodic Pension Expense		0	100,000	0	100,000
U.S Plans | Pension Plan
Defined Benefit plan Net periodic benefit cost
Service Cost		11,900,000	10,400,000	35,500,000	31,200,000
Interest Cost		10,800,000	11,800,000	32,400,000	35,400,000
Expected Return on Plan Assets		(19,200,000)	(21,700,000)	(57,600,000)	(65,100,000)
Amortization
Net Actuarial Loss (Gain)		8,800,000	4,300,000	26,400,000	12,900,000
Prior Service Cost		(100,000)	(100,000)	(300,000)	(300,000)
Net Periodic Pension Expense		12,200,000	4,700,000	36,400,000	14,100,000
Non U.S. Plans | Pension Plan
Defined Benefit plan Net periodic benefit cost
Service Cost		600,000	500,000	1,600,000	1,500,000
Interest Cost		700,000	900,000	2,100,000	2,900,000
Expected Return on Plan Assets		(800,000)	(1,000,000)	(2,300,000)	(2,900,000)
Settlement Expense		100,000	0	300,000	0
Amortization
Net Actuarial Loss (Gain)		200,000	200,000	800,000	500,000
Prior Service Cost		100,000	0	100,000	0
Net Periodic Pension Expense		$ 900,000	$ 600,000	$ 2,600,000	$ 2,000,000

Share-Based Compensation Plan_2

Share-Based Compensation Plans (Compensation Expense for Share-Based Arrangements and Tax Impacts) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 13.9	$ 17.3	$ 82.8	$ 91.3
Tax Benefits Recognized	3.5	4.3	20.6	22.7
Restricted Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	12.2	14	66.3	68.5
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0.1	0.4	0.4	1.1
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1.6	$ 2.9	$ 16.1	$ 21.7

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Variable Interest Entity [Line Items]
Exposure to loss from liquidity arrangements and obligations to purchase assets	$ 0		$ 0
Assets	152,082,000,000		152,082,000,000		$ 136,828,400,000
Liabilities	140,502,900,000		140,502,900,000		125,737,400,000
Affordable housing tax credits and other tax benefits	20,700,000	$ 16,400,000	59,400,000	$ 49,200,000
Contractual obligation to provide financial support	0		0
Fair value, investments, entities that calculate net asset value per share, unfunded commitments	73,300,000		73,300,000		0
Leveraged Leasing Transactions
Variable Interest Entity [Line Items]
Exposure to loss from liquidity arrangements and obligations to purchase assets	0		0
Leveraged Leasing Transactions | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	$ 30,100,000		$ 30,100,000		42,600,000
Leveraged Leasing Transactions | Lower Limit
Variable Interest Entity [Line Items]
Funding of assets cost via equity interest	20.00%		20.00%
Funding of asset's cost via third party non recourse debt holders	70.00%		70.00%
Leveraged Leasing Transactions | Upper Limit
Variable Interest Entity [Line Items]
Funding of assets cost via equity interest	30.00%		30.00%
Funding of asset's cost via third party non recourse debt holders	80.00%		80.00%
Other Assets
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, assets	$ 761,300,000		$ 761,300,000		749,300,000
Alternative investment	1,700,000		1,700,000		112,000,000
Other Assets | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	715,500,000		715,500,000		700,300,000
Other Liabilities
Variable Interest Entity [Line Items]
Investments in community development projects, carrying amount, liabilities	300,000,000		300,000,000		376,200,000
Other Liabilities | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Liabilities	$ 283,500,000		$ 283,500,000		$ 354,300,000

Contingent Liabilities (Narrati

Contingent Liabilities (Narrative) (Details) shares in Millions	Sep. 27, 2019USD ($)	Jun. 28, 2018USD ($)	Jun. 30, 2016USD ($)shares	Jun. 30, 2015USD ($)shares	Mar. 31, 2016trust	Sep. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)shares
Loss Contingencies [Line Items]
Commitments and letters of credit						$ 26,400,000,000	$ 24,400,000,000
Standby letters of credit outstanding						$ 2,100,000,000	$ 2,400,000,000
Minimum securities lending related collateral percentage						100.00%
Loss contingency accrual						$ 0
Visa Class B
Loss Contingencies [Line Items]
Visa redemption gain			$ 123,100,000	$ 99,900,000
Shares issued (in shares) | shares			1.1	1
Common stock shares held (in shares) | shares						4.1	4.1
Remaining Visa shares held by Northern Trust, original cost basis						$ 0	$ 0
Northern Trust Fiduciary Services (Guernsey) Limited | Subsidiaries
Loss Contingencies [Line Items]
Number of administrated trusts serving as trustee on | trust					2
Lower Limit
Loss Contingencies [Line Items]
Possible loss in future periods in excess of accrual						0
Upper Limit
Loss Contingencies [Line Items]
Possible loss in future periods in excess of accrual						15,000,000
Visa Inc. | Visa Class B Litigation Case
Loss Contingencies [Line Items]
Escrow deposit	$ 300,000,000	$ 600,000,000
Indemnification Agreement
Loss Contingencies [Line Items]
Collateralized securities loaned, subject to indemnification						148,300,000,000	138,100,000,000
Credit loss liability						$ 0	$ 0

Derivative Financial Instrume_3

Derivative Financial Instruments (Notional and Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
NOTIONAL VALUE	$ 281,329.7	$ 310,600.7
Assets	2,098	2,844
Total Gross Derivatives, asset	2,613.2	3,387.7
Less: Netting	1,408.3	2,338
Derivative Assets	1,204.9	1,049.7
Liabilities	2,143.8	2,312.4
Derivative Liabilities	2,500.8	3,313
Less: Netting	1,603.3	1,618.4
Derivative Liabilities	897.5	1,694.6
Derivatives Designated as Hedging under GAAP
Derivative [Line Items]
NOTIONAL VALUE	14,555.8	9,273.5
Assets	45.3	102.7
Liabilities	131.1	44.5
Fair Value Hedges | Derivatives Designated as Hedging under GAAP | Interest Rate Contracts
Derivative [Line Items]
NOTIONAL VALUE	5,357.8	4,538.2
Assets	10.2	20.3
Liabilities	18.9	20.9
Fair Value Hedges | Derivatives Not Designated as Hedging under GAAP
Derivative [Line Items]
NOTIONAL VALUE	266,773.9	301,327.2
Assets	2,567.9	3,285
Liabilities	2,369.7	3,268.5
Fair Value Hedges | Non-Designated Risk Management Derivatives
Derivative [Line Items]
NOTIONAL VALUE	760.7	816.8
Assets	2	0.9
Liabilities	32.9	34.1
Fair Value Hedges | Non-Designated Risk Management Derivatives | Foreign Exchange Contracts
Derivative [Line Items]
NOTIONAL VALUE	79.2	176.5
Assets	2	0.9
Liabilities	0.6	0.7
Fair Value Hedges | Non-Designated Risk Management Derivatives | Other Financial Derivatives
Derivative [Line Items]
NOTIONAL VALUE	681.5	640.3
Assets	0	0
Liabilities	32.3	33.4
Fair Value Hedges | Client-Related and Trading Derivatives
Derivative [Line Items]
NOTIONAL VALUE	266,013.2	300,510.4
Assets	2,565.9	3,284.1
Liabilities	2,336.8	3,234.4
Fair Value Hedges | Client-Related and Trading Derivatives | Foreign Exchange Contracts
Derivative [Line Items]
NOTIONAL VALUE	255,799.4	291,533.6
Assets	2,242.7	3,151.7
Liabilities	2,213.5	3,158.1
Fair Value Hedges | Client-Related and Trading Derivatives | Interest Rate Contracts
Derivative [Line Items]
NOTIONAL VALUE	10,213.8	8,976.8
Assets	323.2	132.4
Liabilities	123.3	76.3
Cash Flow Hedges | Derivatives Designated as Hedging under GAAP | Foreign Exchange Contracts
Derivative [Line Items]
NOTIONAL VALUE	5,882.7	1,661.5
Assets	14	8.5
Liabilities	28.9	11.5
Cash Flow Hedges | Derivatives Designated as Hedging under GAAP | Interest Rate Contracts
Derivative [Line Items]
NOTIONAL VALUE	150	200
Assets	0.3	0.2
Liabilities	0	0.2
Net Investment Hedges | Derivatives Designated as Hedging under GAAP | Foreign Exchange Contracts
Derivative [Line Items]
NOTIONAL VALUE	3,165.3	2,873.8
Assets	20.8	73.7
Liabilities	$ 83.3	$ 11.9

Derivative Financial Instrume_4

Derivative Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Gains or losses reclassified into earnings	$ 0	$ 0	$ 0	$ 0
Maximum length of time over which exposure was being hedged			23 months
Net investment gains (losses) recognized in AOCI	$ 117.4	$ (107.6)	$ 29.8	$ (144.1)
Foreign Currency Denominate
Derivative [Line Items]
Estimated net gain (loss) to be reclassified into net income within the next twelve months relating to cash flow hedges			(0.9)
Foreign Currency Denominated Debt Securities
Derivative [Line Items]
Estimated net gain (loss) to be reclassified into net income within the next twelve months relating to cash flow hedges			16.3
SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE
Derivative [Line Items]
Estimated net gain (loss) to be reclassified into net income within the next twelve months relating to cash flow hedges			$ 0.3

Derivative Financial Instrume_5

Derivative Financial Instruments (Location and Amount of Fair Value And Cash Flow Hedge Derivative Gains And Losses Recorded In Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	$ 355.4	$ 620.8	$ 1,290.9	$ 1,923.8
Interest Expense	26.8	203.1	182.1	666.7
Other Operating Income	53.5	45.1	144.4	113
INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	(14.2)	2.8	(11.6)	13.3
Gains (Losses) on cash flow hedges recognized on	4.4	2.6	11.1	20.3
INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	(2.5)	(6)	6.1	(3.9)
Gains (Losses) on cash flow hedges recognized on	0	0	0	0
OTHER OPERATING INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	0	0	0	0
Gains (Losses) on cash flow hedges recognized on	0.3	1.4	0.1	1.1
Interest Rate Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	15.1	(14.9)	(75.6)	(99)
Recognized on hedged items	(15.1)	14.9	75.6	99
Amounts related to interest settlements on derivatives	(14.2)	2.8	(11.6)	13.3
Gains (Losses) on cash flow hedges recognized on	0.2	(0.1)	0.3	(0.5)
Interest Rate Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(2.9)	51.4	152.1	141.6
Recognized on hedged items	2.9	(51.4)	(152.1)	(141.6)
Amounts related to interest settlements on derivatives	(2.5)	(6)	6.1	(3.9)
Gains (Losses) on cash flow hedges recognized on	0	0	0	0
Interest Rate Contracts | OTHER OPERATING INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	0	0	0	0
Recognized on hedged items	0	0	0	0
Amounts related to interest settlements on derivatives	0	0	0	0
Gains (Losses) on cash flow hedges recognized on	0	0	0	0
Foreign Exchange Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	4.2	2.7	10.8	20.8
Foreign Exchange Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	0	0	0	0
Foreign Exchange Contracts | OTHER OPERATING INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	$ 0.3	$ 1.4	$ 0.1	$ 1.1

Derivative Financial Instrume_6

Derivative Financial Instruments (Hedged Items In Fair Value Hedges) (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Carrying value of the hedged items, available for sale debt securities	$ 2,826,200,000	$ 2,981,000,000
Cumulative hedge accounting basis adjustment, available for sale debt securities	63,300,000	3,300,000
Carrying value of the hedged items, senior notes and long-term subordinated debt	2,745,000,000	1,748,500,000
Cumulative hedge accounting basis adjustment, senior notes and long-term subordinated debt	261,800,000	126,900,000
CARRYING VALUE OF THE HEDGED ITEMS	5,571,200,000	4,729,500,000
Cumulative Hedge Accounting Basis Adjustment	325,100,000	130,200,000
Hedged asset fair value hedge discontinued cumulative increase decrease	6,700,000	1,500,000
Hedged liability fair value hedge discontinued cumulative increase decrease	$ 0	$ 0

Derivative Financial Instrume_7

Derivative Financial Instruments (Location and Amount of Gains and Losses Recorded in Income for Derivatives Not Designated As Hedging Under GAAP) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivatives Not Designated as Hedging under GAAP
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	$ 62.8	$ 56.4	$ 233.1	$ 176.1
Non-Designated Risk Management Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	(1.1)	(8.2)	(7.2)	(19.5)
Non-Designated Risk Management Derivatives | Foreign Exchange Contracts | Others Operating Income
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	4.2	(1.8)	3.8	(1.7)
Non-Designated Risk Management Derivatives | Other Financial Derivatives | Others Operating Income
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	(5.3)	(6.4)	(11)	(17.8)
Client-Related and Trading Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	63.9	64.6	240.3	195.6
Client-Related and Trading Derivatives | Foreign Exchange Contracts | Foreign Exchange Trading Income
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	61.6	59.7	221.8	186.4
Client-Related and Trading Derivatives | Interest Rate Contracts | Security Commissions and Trading Income
Derivative Instruments, Gain (Loss) [Line Items]
AMOUNT OF DERIVATIVE GAINS (LOSSES) RECOGNIZED IN INCOME	$ 2.3	$ 4.9	$ 18.5	$ 9.2

Offsetting of Assets and Liab_3

Offsetting of Assets and Liabilities (Offsetting of Derivative Assets and Securities Purchased Under Agreements to Resell) (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	$ 2,098,000,000	$ 2,844,000,000
Gross Amounts Offset in the Balance Sheet	1,408,300,000	2,338,000,000
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	689,700,000	506,000,000
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	29,700,000	16,500,000
Net Amount	660,000,000	489,500,000
Total Derivatives Not Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	515,200,000	543,700,000
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	900,000	300,000
Net Amount	514,300,000	543,400,000
Total Derivatives
GROSS RECOGNIZED ASSETS	2,613,200,000	3,387,700,000
Derivative Assets	1,204,900,000	1,049,700,000
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	30,600,000	16,800,000
Net Amount	1,174,300,000	1,032,900,000
Securities Purchased under Agreements to Resell
GROSS RECOGNIZED ASSETS	1,533,400,000	707,800,000
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	1,533,400,000	707,800,000
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	1,533,400,000	707,800,000
Other assets excluding derivatives and non financial instruments	7,300,000,000	7,400,000,000
Federal funds sold	0	5,000,000
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	1,764,300,000	2,691,100,000
Gross Amounts Offset in the Balance Sheet	1,405,700,000	2,334,100,000
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	358,600,000	357,000,000
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	29,700,000	16,500,000
Net Amount	328,900,000	340,500,000
Interest Rate Swap Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	333,700,000	151,900,000
Gross Amounts Offset in the Balance Sheet	2,600,000	3,900,000
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	331,100,000	148,000,000
Net Amount	$ 331,100,000	148,000,000
Interest Rate Swap Contracts | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS		1,000,000
Gross Amounts Offset in the Balance Sheet		0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET		1,000,000
Net Amount		$ 1,000,000

Offsetting of Assets and Liab_4

Offsetting of Assets and Liabilities (Offsetting of Derivative Liabilities and Securities Sold Under Agreements to Repurchase) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	$ 2,143.8	$ 2,312.4
Gross Amounts Offset in the Balance Sheet	1,603.3	1,618.4
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	540.5	694
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0	0.1
Net Amount	540.5	693.9
Total Derivatives Not Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	357	1,000.6
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0
Net Amount	357	1,000.6
Offsetting Derivative Liabilities [Abstract]
GROSS RECOGNIZED LIABILITIES	2,500.8	3,313
Derivative Liabilities	897.5	1,694.6
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0	0.1
Net Amount	897.5	1,694.5
Securities Sold under Agreements to Repurchase
GROSS RECOGNIZED LIABILITIES	269.8	489.7
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	269.8	489.7
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	269.8	489.7
Other liabilities	3,600	3,100
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	1,969.2	2,181.6
Gross Amounts Offset in the Balance Sheet	1,493.6	1,548.6
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	475.6	633
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0	0.1
Net Amount	475.6	632.9
Interest Rate Swap Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	142.3	96.7
Gross Amounts Offset in the Balance Sheet	109.7	57.3
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	32.6	39.4
Net Amount	32.6	39.4
Interest Rate Swap Contracts | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES		0.7
Gross Amounts Offset in the Balance Sheet		0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET		0.7
Net Amount		0.7
Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	32.3	20.9
Net Amount	32.3	20.9
Other Financial Derivatives | Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	32.3	33.4
Gross Amounts Offset in the Balance Sheet	$ 0	$ 12.5

Offsetting of Assets and Liab_5

Offsetting of Assets and Liabilities (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Offsetting Assets and Liabilities [Line Items]
Collateral received	$ 29.7	$ 16.5
Gross amounts not offset in the balance sheet	0	0.1
Aggregate fair value of all derivative instruments with credit-risk-related contingent features that are in a liability position	565.5	766.2
Collateral deposited with derivative counterparties for derivatives instruments with credit-risk-related contingent features that are in a liability position	184.4	327.1
Net maximum amount of termination payments that could have been required	381.1	439.1
Net Investment Hedges
Offsetting Assets and Liabilities [Line Items]
Collateral received	281
Gross amounts not offset in the balance sheet	$ 280.8
Cash collateral received from derivative counterparties and not offset against derivative assets		196.3
Cash collateral deposited with derivative counterparties not offset against derivative liabilities		$ 2