People's United Financial (PBCT) 10-K 1 Mar 22 2021 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 18, 2022	Jun. 30, 2021
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity Registrant Name	People's United Financial, Inc.
Entity File Number	001-33326
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8447891
Entity Address, Address Line One	850 Main Street
Entity Address, City or Town	Bridgeport
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06604
City Area Code	(203)
Local Phone Number	338-7171
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 7,330
Entity Common Stock, Shares Outstanding		429,671,285
Documents Incorporated by Reference	The information required by Part III is incorporated by reference to our definitive proxy statement or in an amendment to the Form 10-K, to be filed no later than 120 days after the end of the fiscal year covered by this Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Central Index Key	0001378946
Common Stock, $0.01 par value per share
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	PBCT
Security Exchange Name	NASDAQ
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series A, $0.01 par value per share
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series A, $0.01 par value per share
Trading Symbol	PBCTP
Security Exchange Name	NASDAQ

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
Audit Information [Abstract]
Auditor Firm ID	185
Auditor Name	KPMG LLP
Auditor Location	Stamford, Connecticut

Consolidated Statements of Cond

Consolidated Statements of Condition - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets
Cash and due from banks	$ 320.5	$ 477.3
Short-term investments	10,268.8	3,766
Total cash and cash equivalents (note 3)	10,589.3	4,243.3
Securities (note 4):
Equity securities, at fair value	0	5.3
Debt securities available-for-sale, at fair value	6,644	4,925.5
Debt securities held-to-maturity, at amortized cost and net of allowance for credit losses of $1.5 million and $1.6 million (fair value of $4.04 billion and $4.27 billion)	3,841.5	3,993.8
Federal Reserve Bank and Federal Home Loan Bank stock, at cost	264.6	266.6
Total securities	10,750.1	9,191.2
Loans held-for-sale (note 5)	8.8	26.5
Loans (notes 5, 6 and 7):
Loans	37,851.3	43,869.5
Less allowance for credit losses on loans	(343.6)	(425.1)
Total loans, net	37,507.7	43,444.4
Goodwill (notes 2 and 8)	2,680.8	2,680.8
Bank-owned life insurance	710.7	711.6
Premises and equipment, net (note 9)	241.8	276.7
Other acquisition-related intangible assets (notes 2 and 8)	127.8	165.1
Other assets (notes 4, 5, 7, 10 and 23)	2,025.4	2,352.2
Total assets	64,642.4	63,091.8
Deposits (note 11):
Non-interest-bearing	17,941.1	15,881.7
Savings	6,733.7	6,029.7
Interest-bearing checking and money market	25,383.8	24,567.5
Time	3,696.7	5,658.8
Total deposits	53,755.3	52,137.7
Borrowings (note 12):
Federal Home Loan Bank advances	562.6	569.7
Customer repurchase agreements	395.2	452.9
Federal funds purchased	0	125
Total borrowings	957.8	1,147.6
Notes and debentures (note 13)	992.8	1,009.6
Other liabilities (notes 7, 10 and 23)	1,034.7	1,194.1
Total liabilities	56,740.6	55,489
Commitments and contingencies (notes 7, 14, 22 and 23)
Stockholders’ Equity (notes 2, 15, 18, 19 and 20):
Preferred stock ($0.01 par value; 50.0 million shares authorized; 10.0 million shares issued and outstanding at both dates)	244.1	244.1
Common stock ($0.01 par value; 1.95 billion shares authorized; 536.9 million shares and 533.7 million shares issued)	5.4	5.3
Additional paid-in capital	7,723.3	7,663.6
Retained earnings	1,643.2	1,363.6
Accumulated other comprehensive loss	(136.8)	(89.2)
Unallocated common stock of Employee Stock Ownership Plan, at cost (5.2 million shares and 5.6 million shares)	(108.4)	(115.6)
Treasury stock, at cost (109.0 million shares at both dates)	(1,469)	(1,469)
Total stockholders’ equity	7,901.8	7,602.8
Total liabilities and stockholders’ equity	64,642.4	63,091.8
Commercial
Loans (notes 5, 6 and 7):
Loans	29,131.9	33,249.2
Less allowance for credit losses on loans	(201.6)	(303.6)
Retail Loans
Loans (notes 5, 6 and 7):
Loans	8,719.4	10,620.3
Less allowance for credit losses on loans	(142)	(121.5)
Commercial real estate | Commercial
Loans (notes 5, 6 and 7):
Loans	11,936.7	13,336.9
Commercial and industrial | Commercial
Loans (notes 5, 6 and 7):
Loans	12,052.1	14,982.3
Equipment financing | Commercial
Loans (notes 5, 6 and 7):
Loans	5,143.1	4,930
Residential mortgage | Retail Loans
Loans (notes 5, 6 and 7):
Loans	7,004.3	8,518.9
Home equity and other consumer | Retail Loans
Loans (notes 5, 6 and 7):
Loans	$ 1,715.1	$ 2,101.4

Consolidated Statements of Co_2

Consolidated Statements of Condition (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for held-to-maturity debt	$ 1.5	$ 1.6
Securities held to maturity, at fair value	$ 4,036.1	$ 4,267
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Preferred stock, shares issued (in shares)	10,000,000	10,000,000
Preferred stock, shares outstanding (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,950,000,000	1,950,000,000
Common stock, shares issued (in shares)	536,900,000	533,700,000
Unallocated common stock of Employee Stock Ownership Plan (in shares)	5,226,787	5,600,000
Treasury stock (in shares)	109,000,000	109,000,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest and dividend income:
Commercial real estate	$ 387.1	$ 488.6	$ 556.4
Commercial and industrial	431.6	440.8	443.6
Equipment financing	250.5	263.3	253.8
Residential mortgage	250.3	332.2	329.1
Home equity and other consumer	62.2	86.7	106.1
Total interest on loans	1,381.7	1,611.6	1,689
Securities	209.7	195.7	186.5
Short-term investments	9.5	3.4	4.8
Loans held-for-sale	0.4	4.3	0.8
Total interest and dividend income	1,601.3	1,815	1,881.1
Interest expense:
Deposits (note 11)	68.7	187.2	356.9
Borrowings (note 12)	4.7	20.2	77
Notes and debentures	28.8	31.8	34.9
Total interest expense	102.2	239.2	468.8
Net interest income	1,499.1	1,575.8	1,412.3
Provision for credit losses on loans (note 6)	(48.2)	156.1	28.3
Provision for credit losses on securities (note 4)	(0.1)	(0.3)	0
Net interest income after provisions for credit losses	1,547.4	1,420	1,384
Non-interest income:
Operating lease income (note 7)	44.7	49.7	50.8
Cash management fees	37.7	33.4	28.4
Gain on sale of business, net of expenses (note 2)	0	75.9	0
Other non-interest income (notes 2, 4, 5 and 7)	72.3	112.1	123.5
Total non-interest income	393.6	492.7	431.1
Non-interest expense:
Compensation and benefits (notes 19 and 20)	679.6	674.8	646.2
Occupancy and equipment (notes 7 and 9)	196.5	199	185.9
Professional and outside services	119.3	113.2	98.2
Amortization of other acquisition-related intangible assets (note 8)	37	40.8	32.5
Operating lease expense	29.3	36.4	38.8
Regulatory assessments	28.2	32.7	26.1
Goodwill impairment (note 8)	0	353	0
Other non-interest expense	93.9	114.2	135
Total non-interest expense	1,183.8	1,564.1	1,162.7
Income before income tax expense	757.2	348.6	652.4
Income tax expense (note 14)	152.3	129	132
Net income	604.9	219.6	520.4
Preferred stock dividend	14.1	14.1	14.1
Net income available to common shareholders	$ 590.8	$ 205.5	$ 506.3
Earnings per common share (note 17):
Basic (in dollars per share)	$ 1.40	$ 0.49	$ 1.28
Diluted (in dollars per share)	$ 1.39	$ 0.49	$ 1.27
Bank service charges
Non-interest income:
Revenue from contract with customer	$ 100.1	$ 97.5	$ 107.5
Investment management fees
Non-interest income:
Revenue from contract with customer	83	73.2	78.2
Commercial banking lending fees
Non-interest income:
Revenue from contract with customer	$ 55.8	$ 50.9	$ 42.7

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 604.9	$ 219.6	$ 520.4
Net actuarial gains and losses on pension and other postretirement plans:
Net actuarial gains (losses) arising during the year	79.8	(15.7)	12.1
Reclassification adjustment for net actuarial loss included in net income	9	8.4	8.3
Net actuarial gains (losses)	88.8	(7.3)	20.4
Net unrealized gains and losses on securities available-for-sale:
Net unrealized holding (losses) gains arising during the year	(160.8)	107.8	89.2
Reclassification adjustment for net realized gains included in net income	0	0	(0.1)
Net unrealized (losses) gains	(160.8)	107.8	89.1
Net unrealized gains and losses on securities transferred to held-to-maturity:
Reclassification adjustment for amortization of unrealized losses on securities transferred to held-to-maturity included in net income	4.9	4.7	4.6
Net unrealized gains	4.9	4.7	4.6
Net unrealized gains and losses on derivatives accounted for as cash flow hedges:
Net unrealized gains (losses) arising during the year	1.2	(1.4)	1.9
Reclassification adjustment for net realized losses (gains) included in net income	1.8	(2)	1.1
Net unrealized gains (losses)	3	(3.4)	3
Other comprehensive (loss) income, before tax	(64.1)	101.8	117.1
Deferred income tax benefit (expense) related to other comprehensive (loss) income	16.5	(24.1)	(27.2)
Total other comprehensive (loss) income, net of tax	(47.6)	77.7	89.9
Total comprehensive income	$ 557.3	$ 297.3	$ 610.3

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	BSB Bancorp	United Financial	Preferred Stock	Common Stock, $0.01 par value per share	Common Stock, $0.01 par value per shareBSB Bancorp	Common Stock, $0.01 par value per shareUnited Financial	Additional Paid-In Capital	Additional Paid-In CapitalBSB Bancorp	Additional Paid-In CapitalUnited Financial	Retained Earnings	Retained EarningsCumulative Effect, Period of Adoption, Adjustment	Unallocated ESOP Common Stock	[1]	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning Balance at Dec. 31, 2018	$ 6,533.9				$ 244.1	$ 4.7			$ 6,549.3			$ 1,284.8		$ (130.1)		$ (256.8)	$ (1,162.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	520.4											520.4
Total other comprehensive income (loss), net of tax	89.9															89.9
Common stock issued in acquisitions	1,045.1		$ 324.5	$ 720.6			$ 0.2	$ 0.4		$ 324.3	$ 720.2
Cash dividends on common stock	(274.8)											(274.8)
Cash dividends on preferred stock	(14.1)											(14.1)
Restricted stock and performance-based share awards	16.3								16.3
Common stock repurchased (note 15)	(2.5)																(2.5)
ESOP common stock committed to be released (note 19)	5.7											(1.5)		7.2
Common stock repurchased and retired upon vesting of restricted stock awards (note 20)	(2)											(2)
Stock options exercised	29.3								29.3
Ending Balance at Dec. 31, 2019	7,947.2	$ (45.9)			244.1	5.3			7,639.4			1,512.8	$ (45.9)	(122.9)		(166.9)	(1,164.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	219.6											219.6
Total other comprehensive income (loss), net of tax	77.7															77.7
Common stock issued in acquisitions	0
Cash dividends on common stock	(304.1)											(304.1)
Cash dividends on preferred stock	(14.1)											(14.1)
Restricted stock and performance-based share awards	17.2								17.2
Common stock repurchased (note 15)	(304.4)																(304.4)
ESOP common stock committed to be released (note 19)	4.3											(3)		7.3
Common stock repurchased and retired upon vesting of restricted stock awards (note 20)	(1.7)											(1.7)
Stock options exercised	7								7
Ending Balance at Dec. 31, 2020	7,602.8				244.1	5.3			7,663.6			1,363.6		(115.6)		(89.2)	(1,469)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	604.9											604.9
Total other comprehensive income (loss), net of tax	(47.6)															(47.6)
Common stock issued in acquisitions	0
Cash dividends on common stock	(307.8)											(307.8)
Cash dividends on preferred stock	(14.1)											(14.1)
Restricted stock and performance-based share awards	18								18
ESOP common stock committed to be released (note 19)	5.9											(1.3)		7.2
Common stock repurchased and retired upon vesting of restricted stock awards (note 20)	(2.1)											(2.1)
Stock options exercised	41.8					0.1			41.7
Ending Balance at Dec. 31, 2021	$ 7,901.8				$ 244.1	$ 5.4			$ 7,723.3			$ 1,643.2		$ (108.4)		$ (136.8)	$ (1,469)
[1]	Employee Stock Ownership Plan

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash dividends on common stock (in dollars per share)	$ 0.7275	$ 0.7175	$ 0.7075
Retained Earnings
Cash dividends on common stock (in dollars per share)	$ 0.7275	$ 0.7175	$ 0.7075

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities:
Net income	$ 604.9	$ 219.6	$ 520.4
Adjustments to reconcile net income to net cash provided by operating activities:
Provisions for credit losses	(48.3)	155.8	28.3
Depreciation and amortization of premises and equipment	44	43.4	41.7
Amortization of other acquisition-related intangible assets	37	40.8	32.5
Expense related to operating leases	29.3	36.4	38.8
Expense related to share-based awards	27.6	26.2	24.9
Deferred income tax expense (benefit)	2.6	(18.7)	14.3
ESOP common stock committed to be released	5.9	4.3	5.7
Net gains on sales of loans	0	(15.5)	(0.4)
Net gains on sales of residential mortgage loans held-for-sale	(1.6)	(4.8)	(1.9)
Originations of loans held-for-sale	(47.8)	(213.8)	(180.3)
Proceeds from sales of loans held-for-sale	67.1	703.4	181.9
Net decrease in trading debt securities	0	7.1	1.3
Excess income tax benefits from stock options exercised	1	0	0.3
Goodwill impairment (note 8)	0	353	0
Net changes in other assets and other liabilities	494.4	(494.3)	(466.7)
Net cash provided by operating activities	1,216.1	842.9	240.8
Cash Flows from Investing Activities:
Proceeds from sales of equity securities	6.4	2	1.6
Proceeds from principal repayments and maturities of debt securities available-for-sale	1,316.9	1,307.5	578.5
Proceeds from sales of debt securities available-for-sale	145.6	0	365.3
Proceeds from principal repayments and maturities of debt securities held-to-maturity	283.7	262.5	158.2
Purchases of debt securities available-for-sale	(3,517.4)	(2,398.9)	(827.8)
Purchases of debt securities held-to-maturity	(162.8)	(406.8)	(257.9)
Net purchases of Federal Reserve Bank stock	(0.8)	(24.6)	(25.2)
Net redemptions of Federal Home Loan Bank stock	2.8	99	19.3
Proceeds from sales of loans	54.6	102.1	51.2
Net principal collections (disbursements) of loans	5,968	(293.3)	(770.3)
Purchases of loans	(95)	(50.3)	(71.2)
Purchases of premises and equipment	(28.6)	(37.1)	(26.5)
Purchases of leased equipment, net	0	(8.7)	(41.2)
Proceeds from sales of real estate owned	8.8	11.7	13.9
Return of premiums on bank-owned life insurance, net	7.4	2.1	2.2
Net cash acquired in acquisitions and dispositions	0	114.8	519.4
Net cash provided by (used in) investing activities	3,989.6	(1,318)	(310.5)
Cash Flows from Financing Activities:
Net increase (decrease) in deposits	1,617.6	8,548.2	(117.6)
Net (decrease) increase in borrowings with terms of three months or less	(182.7)	(3,952)	647.7
Repayments of borrowings with terms of more than three months	(7.2)	(55.2)	(321.2)
Cash dividends paid on common stock	(307.8)	(304.1)	(274.8)
Cash dividends paid on preferred stock	(14.1)	(14.1)	(14.1)
Repurchases of common stock	(2.1)	(306.1)	(4.5)
Proceeds from stock options exercised	36.6	0.7	24.1
Contingent consideration payments	0	0	(0.9)
Net cash provided by (used in) financing activities	1,140.3	3,917.4	(61.3)
Net increase (decrease) in cash and cash equivalents	6,346	3,442.3	(131)
Cash and cash equivalents at beginning of year	4,243.3	801	932
Cash and cash equivalents at end of year	10,589.3	4,243.3	801
Supplemental Information:
Interest payments	102.3	248.1	473.4
Income tax payments	89.5	109.7	107.7
Significant non-cash transactions:
Unsettled purchases of securities	45.5	194.8	0
Right-of-use assets obtained in exchange for lessee operating and finance lease liabilities	31.4	22.8	91.7
Real estate properties acquired by foreclosure	3.1	4.8	19.9
Assets (disposed) acquired and liabilities (disposed) assumed in acquisitions and dispositions (note 2):
Non-cash assets, excluding goodwill and other acquisition-related intangibles	0	(18.4)	9,224.7
Liabilities	0	(14.4)	9,120.4
Common stock issued in acquisitions	$ 0	$ 0	$ 1,045.1

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 1 – Summary of Significant Accounting Policies People’s United Financial, Inc. (“People’s United” or the “Company”) is a bank holding company and a financial holding company registered under the Bank Holding Company Act of 1956, as amended, and is incorporated under the state laws of Delaware. People’s United is the holding company for People’s United Bank, National Association (the “Bank”), a national banking association headquartered in Bridgeport, Connecticut. The principal business of People’s United is to provide, through the Bank and its subsidiaries, commercial banking, retail banking and wealth management services to individual, corporate and municipal customers. The Bank provides a full-range of traditional banking services, including accepting deposits and originating loans, as well as specialized financial services through its non-bank subsidiaries, including: equipment financing provided through People’s Capital and Leasing Corp. (“PCLC”), People’s United Equipment Finance Corp. (“PUEFC”) and LEAF Commercial Capital, Inc. (“LEAF”); brokerage, financial advisory services, investment management services and life insurance provided through People’s Securities, Inc. (“PSI”) and investment advisory services and financial management and planning services provided through People’s United Advisors, Inc. (“PUA”). The Company’s overall financial results are particularly dependent on economic conditions in New England and New York, which are its primary markets, although economic conditions elsewhere in the United States affect its national equipment financing business. People’s United is regulated by the Board of Governors of the Federal Reserve System (the “FRB”) and subject to FRB examination, supervision and reporting requirements. The Bank is regulated by the Office of the Comptroller of the Currency (the “OCC”) and subject to OCC examination, supervision and reporting requirements. Deposits are insured up to applicable limits by the Deposit Insurance Fund of the Federal Deposit Insurance Corporation (the “FDIC”). On March 11, 2020, the World Health Organization declared the outbreak of a strain of novel coronavirus disease (“COVID-19”) a global pandemic. Economic activity in many countries, including the United States, began to deteriorate rapidly as the COVID-19 pandemic spread across the globe. In the United States, which has been operating under a presidentially-declared national emergency since March 13, 2020, the COVID-19 pandemic caused severe disruption to the capital markets as well as business and economic activity. In response, individual municipalities and entire states adopted travel and work location restrictions, social distancing requirements, and in some cases, shelter-in-place protocols in order to slow the spread of the virus. These measures resulted in the closure of many schools, stores, offices, restaurants and manufacturing facilities, causing a decline in spending and an increase in layoffs. In response, the Federal government introduced several measures to mitigate the magnitude of the pandemic’s effects. Most notably, on March 27, 2020, The Coronavirus Aid, Relief and Economic Security Act (the “CARES Act”), which provides financial assistance for businesses and individuals as well as targeted regulatory relief for financial institutions, was signed into law. This relief package was subsequently followed by additional government stimulus in the form of The Consolidated Appropriations Act, 2021 in December 2020, The American Rescue Plan in March 2021, The Coronavirus Economic Relief for Transportations Services Program in August 2021 and The Infrastructure Investment and Jobs Act in November 2021. Also in March 2020, the Federal Open Market Committee of the Federal Reserve reduced short-term interest rates by 150 basis points (to near zero) and announced various other initiatives to enhance liquidity and support the flow of credit to households and businesses. The impact of the COVID-19 pandemic on economic conditions, both in the United States and abroad, has created global uncertainty about the future economic environment including the length and depth of any global recession that may occur. Concerns over interest rates, domestic and global policy issues, U.S. trade policy and geopolitical events, and the influence of those factors on the markets in general, further add to this uncertainty. Basis of Financial Statement Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of People’s United and its subsidiaries. All significant intercompany transactions and balances are eliminated in consolidation. Certain reclassifications have been made to prior period amounts to conform to the current period presentation. In preparing the consolidated financial statements, management is required to make significant estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. Actual results could differ from management’s current estimates, as a result of changing conditions and future events. Several accounting estimates are particularly critical and are susceptible to significant near-term change, including the allowance for credit losses (“ACL”) and the recoverability of goodwill and other intangible assets. These accounting estimates, which are included in the discussion below, are reviewed with the Audit Committee of the Board of Directors. The Financial Accounting Standards Board (the “FASB”) issued changes to several accounting standards, some of which govern key aspects of the Company’s financial statements. Most notably, the FASB’s standard on accounting for credit losses (the “CECL standard”), removed from U.S. GAAP the existing “probable” threshold for recognizing credit losses and, instead, utilizes an “expected credit loss” measurement principle. The CECL standard, which was adopted by the Company on The judgments used by management in applying critical accounting policies may be affected by economic conditions, which may result in changes to future financial results. For example, subsequent evaluations of the loan portfolio, in light of the factors then prevailing, may result in significant changes in the ACL in future periods, and the inability to collect outstanding principal may result in increased loan losses. For purposes of the Consolidated Statements of Cash Flows, cash equivalents include highly-liquid instruments, such as: (i) interest-bearing deposits at the Federal Reserve Bank of New York (the “FRB-NY”); (ii) government-sponsored enterprise (“GSE”) debt securities with an original maturity of three months or less (determined as of the date of purchase); (iii) federal funds sold; (iv) commercial paper; and (v) money market mutual funds. These instruments are reported as short-term investments in the Consolidated Statements of Condition at cost or amortized cost, which approximates fair value. GSE debt securities classified as cash equivalents are held to maturity and carry the implicit backing of the U.S. government, but are not direct obligations of the U.S. government. Securities Marketable debt securities (other than those reported as short-term investments) are classified as either trading debt securities, debt securities held-to-maturity or debt securities available-for-sale. Management determines the classification of a security at the time of its purchase and reevaluates such classification at each balance sheet date. Debt securities purchased for sale in the near term as well as those securities held by PSI (in accordance with the requirements for a broker-dealer) are classified as trading debt securities and reported at fair value with gains and losses reported in non-interest income. Debt securities for which People’s United has the intent and ability to hold to maturity are classified as held-to-maturity securities and reported at amortized cost. All other debt securities are classified as available-for-sale and reported at fair value with unrealized gains and losses reported on an after-tax basis in stockholders’ equity as a component of accumulated other comprehensive income (loss) (“AOCL”). Premiums (discounts) are amortized (accreted) to interest income for debt securities, using the interest method over the remaining period to contractual maturity, adjusted for the effect of actual prepayments in the case of mortgage-backed and collateralized mortgage obligation (“CMO”) securities. Security transactions are recorded on the trade date. Realized gains and losses are determined using the specific identification method and reported in non-interest income. Debt securities transferred from available-for-sale to held-to-maturity are recorded at fair value at the date of transfer. The unrealized pre-tax gain or loss resulting from the difference between fair value and amortized cost at the transfer date becomes part of the new amortized cost basis of the securities and remains in AOCL. Such unrealized gains or losses are amortized to interest income as an adjustment to yield over the remaining life of the securities, offset by the amortization (accretion) of the premium (discount) resulting from the transfer at fair value, with no effect to net income. In connection with the Company's adoption of the CECL standard on January 1, 2020, selected accounting policies related to securities were revised and/or certain accounting policy elections were implemented. These policies are described below. Allowance for Credit Losses – Available-for-Sale Securities For available-for sale securities in an unrealized loss position, management first assesses whether (i) the Company intends to sell, or (ii) it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either criteria are met, any previously recognized ACL (see below) is charged-off and the security's amortized cost is written down to fair value through income. If neither criteria are met, the security is evaluated to determine whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, management considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, an ACL is recorded for the credit loss, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that has not been recorded through an ACL is recognized in other comprehensive income. Adjustments to the ACL are reported as a component of credit loss expense. Available-for-sale securities are Allowance for Credit Losses – Held-to-Maturity Securities Management measures expected credit losses on held-to-maturity securities on a collective basis by major security type with each type sharing similar risk characteristics, and considers historical credit loss information that is adjusted for current conditions and reasonable and supportable forecasts. Held-to-maturity securities are charged-off against the ACL when deemed to be uncollectible and adjustments to the ACL are reported as a component of credit loss expense. The Company has made the accounting policy election to exclude accrued interest receivable on held-to-maturity securities from the estimate of credit losses. With regard to U.S. Treasury and residential mortgage-backed securities issued by the U.S. government, or agencies thereof, it is expected that the securities will not be settled at prices less than the amortized cost bases of the securities as such securities are backed by the full faith and credit of and/or guaranteed by the U.S. government. Accordingly, no ACL has been recorded for these securities. With regard to securities issued by corporations, states and/or political subdivisions and other held-to-maturity securities, management considers a number of factors, including: (i) issuer bond ratings; (ii) historical loss rates for given bond ratings; and (iii) whether issuers continue to make timely principal and interest payments under the contractual terms of the securities. For periods prior to January 1, 2020, management conducted periodic reviews and evaluation of the debt securities portfolio to determine if the decline in fair value of any security was deemed to be other-than-temporary. Other-than-temporary impairment losses were recognized on debt securities when: (i) People’s United had an intention to sell the security; (ii) it was more likely than not that People’s United would be required to sell the security prior to recovery; or (iii) People’s United did not expect to recover the entire amortized cost basis of the security. Other-than-temporary impairment losses on debt securities were reflected in earnings as realized losses to the extent the impairment is related to credit losses of the issuer. The amount of the impairment related to other factors was recognized in other comprehensive income. Both FRB-NY stock and Federal Home Loan Bank (“FHLB”) stock are non-marketable equity securities and are, therefore, reported at their respective costs, which equals par value (the amount at which shares have been redeemed in the past). These investments are periodically evaluated for impairment based on, among other things, the capital adequacy of the FRB-NY or the FHLB and their overall financial condition. Equity securities are reported at fair value with gains and losses reported in non-interest income. Securities Resale and Securities Repurchase Agreements In securities resale agreements, a counterparty transfers securities to People’s United (as transferee) and People’s United agrees to resell the same securities to the counterparty at a fixed price in the future. In securities repurchase agreements, People’s United accounts for securities resale agreements as secured lending transactions and securities repurchase agreements as secured borrowings since the transferor maintains effective control over the transferred securities and the transfer meets the other criteria for such accounting. The securities are pledged by the transferor as collateral and the transferee has the right by contract to repledge that collateral provided the same collateral is returned to the transferor upon maturity of the underlying agreement. The fair value of the pledged collateral approximates the recorded amount of the secured loan or borrowing. Decreases in the fair value of the transferred securities below an established threshold require the transferor to provide additional collateral. Loans Held-for-Sale Loans held-for-sale are reported at the lower of cost or fair value in the aggregate with any adjustment for net unrealized losses reported in non-interest income. Management identifies and designates as loans held-for-sale certain newly-originated adjustable-rate and fixed-rate residential mortgage loans that meet secondary market requirements, as these loans are originated with the intent to sell. From time to time, management may also identify and designate certain loans previously Loans As a result of adopting the CECL standard on January 1, 2020, the Company’s prior distinction between the originated loan portfolio and the acquired loan portfolio is no longer necessary. In addition, selected accounting policies related to loans were revised and/or certain accounting policy elections were implemented. These policies are described below. Basis of Accounting Loans are reported at amortized cost less the ACL. Interest on loans is accrued to income monthly based on outstanding principal balances. Loan origination fees and certain direct loan origination costs are deferred, and the net fee or cost is recognized in interest income as an adjustment of yield. Depending on the loan portfolio, amounts are amortized or accreted using the level yield method over either the actual life or the estimated average life of the loan. Allowance for Credit Losses The ACL on loans, calculated in accordance with the CECL standard, is deducted from the amortized cost basis of loans to present the net amount expected to be collected. The amount of the allowance represents management’s best estimate of current expected credit losses on loans considering available information, from both internal and external sources, deemed relevant to assessing collectability over the loans' contractual terms, adjusted for anticipated prepayments, as appropriate. Accrued interest on loans is excluded from the calculation of the ACL due to the Bank’s established non-accrual policy, which results in the reversal of uncollectible accrued interest on non-accrual loans against interest income in a timely manner Purchased Credit Deteriorated Loans In addition to originating loans, the Company may acquire loans through portfolio purchases or acquisitions of other companies. Purchased loans that have evidence of more than insignificant credit deterioration since origination are deemed purchased credit deteriorated (“PCD”) loans. In connection with its adoption of the CECL standard, the Company did not reassess whether previously recognized purchased credit impaired (“PCI”) loans accounted for under prior accounting guidance met the criteria of a PCD loan as of the date of adoption. PCD loans are initially recorded at fair value along with an ACL determined using the same methodology as originated loans. The sum of the loan's purchase price and ACL becomes its initial amortized cost basis. The difference between the initial amortized cost basis and the par value of the loan is a noncredit discount or premium, which is amortized into interest income over the life of the loan. Subsequent changes to the ACL are recorded through provision for credit losses. Past Due and Non-Accrual Loans Loans are considered past due if required principal and interest payments have not been received as of the date such payments were contractually due. A loan is generally considered “non-performing” when it is placed on non-accrual status. A loan is generally placed on non-accrual status when it becomes 90 days past due as to interest or principal payments. A loan may be placed on non-accrual status before it reaches 90 days past due if such loan has been identified as presenting uncertainty with respect to the collectability of interest and principal. A loan past due 90 days or more may remain on accruing status if such loan is both well secured and in the process of collection. All previously accrued but unpaid interest on non-accrual loans is reversed from interest income in the period in which the accrual of interest is discontinued. Interest payments received on non-accrual loans are generally applied as a reduction of principal if future collections are doubtful, although such interest payments may be recognized as income. A loan remains on non-accrual status until the factors that indicated doubtful collectability no longer exist or until a loan is determined to be uncollectible and is charged-off against the ACL. There were no loans past due 90 days or more and still accruing interest at December 31, 2021, 2020 or 2019. Collateral Dependent Loans Loans for which the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the operation or sale of the collateral are considered to be collateral dependent loans. Collateral can have a significant financial effect in mitigating exposure to credit risk and, where there is sufficient collateral, an allowance for expected credit losses is not recognized or is minimal. For collateral dependent commercial loans, the allowance for expected credit losses is individually assessed based on the fair value of the collateral. Various types of collateral are used, including real estate, inventory, equipment, accounts receivable, securities and cash, among others. For commercial real estate loans, collateral values are generally based on appraisals which are updated based on management judgment under the specific circumstances on a case-by-case basis. The collateral value for other financial assets is generally based on quoted market prices or broker quotes (in the case of securities) or appraisals. Commercial loan balances are charged-off at the time all or a portion of the balance is deemed uncollectible. Collateral dependent residential mortgage and home equity loans are carried at the lower of amortized cost or fair value of the collateral less costs to sell, with any excess in the carrying amount of the loan representing the related ACL. Collateral values are based on broker price opinions or appraisals. Troubled Debt Restructurings Troubled debt restructurings (“TDRs”), which, beginning in 2020, also includes loans reasonably expected to become TDRs, represent loans for which the original contractual terms have been modified to provide for terms that are less than what the Company would be willing to accept for new loans with comparable risk because of deterioration in the borrower's financial condition. Such loan modifications are handled on a case-by-case basis and are negotiated to achieve mutually agreeable terms that maximize loan collectability and meet the borrower’s financial needs. Modifications may include changes to one or more terms of the loan, including, but not limited to: (i) payment deferral; (ii) a reduction in the stated interest rate for the remaining contractual life of the loan; (iii) an extension of the loan’s original contractual term at a stated interest rate lower than the current market rate for a new loan with similar risk; (iv) capitalization of interest; or (v) forgiveness of principal or interest. TDRs may either be accruing or placed on non-accrual status (and reported as non-accrual loans) depending upon the loan’s specific circumstances, including the nature and extent of the related modifications. TDRs on non-accrual status remain classified as such until the loan qualifies for return to accrual status. Loans qualify for return to accrual status once they have demonstrated performance with the restructured terms of the loan agreement for a minimum of six months in the case of a commercial loan or, in the case of a retail loan, when the loan is less than 90 days past due. Loans may continue to be reported as TDRs after they are returned to accrual status. In accordance with regulatory guidance, residential mortgage and home equity loans restructured in connection with the borrower’s bankruptcy and meeting certain criteria are also required to be classified as TDRs, included in non-accrual loans and written down to the estimated collateral value, regardless of delinquency status. The CARES Act and guidance issued by the Federal banking agencies provides that certain loan modifications to borrowers experiencing financial distress as a result of the economic impacts created by the COVID-19 pandemic are not required to be treated as TDRs under GAAP. As such, the Company suspended TDR accounting for COVID-19 related loan modifications meeting the loan modification criteria set forth under the CARES Act or as specified in the regulatory guidance. Further, loans granted payment deferrals related to COVID-19 are not required to be reported as past due or placed on Allowance and Provision for Credit Losses The ACL is established through provisions for credit losses on loans charged to income. Losses on loans are charged to the ACL when all or a portion of a loan is deemed to be uncollectible. Recoveries of loans previously charged off are credited to the ACL when realized. On January 1, 2020, the Company adopted the CECL standard, which requires the measurement of expected credit losses for financial assets measured at amortized cost, including loans, and certain off-balance-sheet credit exposures. Allowance for Credit Losses – Loans Under the CECL standard, the Company determines the ACL on loans based upon a consideration of its historical portfolio loss experience, current borrower-specific risk characteristics, forecasts of future economic conditions and other relevant factors. The allowance is measured on a collective (pool) basis when similar risk characteristics exist. Loans that do not share common risk characteristics are evaluated on an individual basis and are excluded from the collective evaluation. The Company’s loan portfolio segments include Commercial and Retail and each of these segments comprises multiple loan classes, which are characterized by similarities in initial measurement, risk attributes, and the manner in which credit risk is monitored and assessed. The Commercial loan portfolio segment is comprised of the commercial real estate, commercial and industrial, equipment financing and mortgage warehouse/asset based lending (“MW/ABL”) loan classes. The Retail loan portfolio segment is comprised of the residential mortgage, home equity and other consumer loan classes. Common characteristics and risk profiles include the type/purpose of loan and historical/expected credit loss patterns. The Company periodically reassesses each pool to ensure the loans within the pool continue to share similar characteristics and risk profiles and to determine whether further segmentation is necessary. The ACL on loans represents management’s current estimate of lifetime expected credit losses inherent in the loan portfolio at the balance sheet date. As such, the estimate of expected credit losses is dependent upon portfolio size, composition and credit quality, as well as economic conditions and forecasts existing at that time. Expected future losses are estimated for the loan's entire contractual term adjusted for anticipated prepayments, as appropriate. The contractual term excludes expected extensions, renewals, and modifications unless (i) management has a reasonable expectation that a TDR will be executed with an individual borrower or (ii) such extension or renewal options are not unconditionally cancellable by the Company and, in such cases, the borrower is likely to meet applicable conditions and likely to request extension or renewal. Credit loss expense related to loans reflects the totality of actions taken on all loans for a particular period including any necessary increases or decreases in the allowance related to changes in credit loss expectations associated with specific loans or pools of loans. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged-off. While management utilizes its best judgment and information available, the ultimate appropriateness of the allowance is dependent upon a variety of factors beyond management's control, including the performance of the loan portfolio, changes in interest rates and the broader economy. The ACL on loans is comprised of three components: (i) quantitative (formulaic) reserves; (ii) qualitative (judgmental) reserves; and (iii) individual loan reserves. Quantitative Component. Management estimates the quantitative component by projecting (i) probability-of-default, representing the likelihood that a loan will stop performing/default (“PD”), (ii) loss-given-default, representing the expected loss rate for loans in default (“LGD”) and (iii) exposure-at-default (“EAD”), representing the estimated outstanding principal balance of the loans upon default, adjusted for anticipated prepayments, as appropriate, based on economic parameters for each month of a loan’s remaining contractual term. Expected credit losses for the quantitative component are calculated as the product of the PD, LGD and EAD. Historical credit experience provides the basis for the estimation of expected credit losses, with adjustments made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix, delinquency levels and terms, as well as for changes in the economic environment over a reasonable and supportable forecast period. The Company utilizes a two-year reasonable and supportable forecast period followed by a one-year period over which estimated losses revert, on a straight-line basis, to average historical loss experience, determined over the historical observation period, for the remaining life of the loan. PDs are estimated by analyzing internal data related to the historical performance of each loan pool over an economic cycle. PDs are adjusted to reflect the current impact of certain macroeconomic variables as well as their expected changes over the reasonable and supportable forecast period. The LGD is based on historical losses for each loan pool, adjusted to reflect the current impact of certain macroeconomic variables as well as their expected changes over a two-year forecast period. EAD is estimated using a linear regression model that estimates the average percentage of the loan balance that remains at the time of a default event. The macroeconomic variables utilized as inputs in the Company’s quantitative modeling process were selected primarily based on their relevance and correlation to historical credit losses. The Company’s quantitative models yield a measurement of expected credit losses reflective of average historical loss rates for periods subsequent to the reasonable and supportable forecast period by reverting such modeling inputs to their historical mean while also considering loan/borrower specific attributes. This same forecast/reversion period is used for all macroeconomic variables employed in all of the Company’s models. The measurement of expected credit losses is impacted by loan/borrower attributes and certain macroeconomic variables derived from an externally-sourced forward-looking economic scenario. Significant loan/borrower attributes utilized in the Company’s quantitative modeling include, among other things: (i) origination date; (ii) maturity date; (iii) payment type; (iv) collateral type and amount; (v) current risk rating (as applicable); (vi) current unpaid balance and commitment utilization rate; and (vii) payment status/delinquency history. Significant macroeconomic variables utilized in the Company’s quantitative modeling include, among other things: (i) U.S. Gross Domestic Product (“GDP”); (ii) selected market interest rates including U.S. Treasury rates, Prime rate, 30-year fixed mortgage rate, BBB corporate bond rate (spread), among others; Qualitative Component. The ACL on loans also includes qualitative considerations related to idiosyncratic risk factors, changes in current economic conditions that may not be reflected in quantitatively-derived results, weightings to economic scenarios based on an assessment of the economic outlook and other relevant factors. These qualitative adjustments may increase or decrease management's estimate of expected credit losses by a calculated percentage or amount based upon the estimated level of risk. The various risks that may be considered in making qualitative adjustments include, among other things, the impact of: The weighted estimate of expected credit losses under various economic scenarios is compared to the result of the Baseline scenario with the difference included as an element of the qualitative component. The Company recognizes an approach using three scenarios may be insufficient in certain economic environments. This may result in a change to the weighting assigned to the three scenarios or the inclusion of additional scenarios. For instance, as a result of a deterioration in U.S. economic conditions caused by the emergence, in March 2020, of the COVID-19 pandemic, and the corresponding increase in economic uncertainty, a fourth forward-looking economic scenario (the “Severe Downside” scenario) has also been considered for purposes of estimating expected credit losses since that time. While the Company’s loss estimation methodologies strive to reflect all relevant risk factors, uncertainty exists associated with, but not limited to, potential imprecision in the estimation process due to the inherent time lag of obtaining information and normal variations between estimates and actual outcomes, including with respect to forward-looking economic forecasts. The qualitative component is designed to a

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2021
Business Combination and Asset Acquisition [Abstract]
Acquisitions and Dispositions	NOTE 2 – Acquisitions and Dispositions Pending Acquisition On February 22, 2021, People’s United and M&T Bank Corporation (“M&T”) announced that they have entered into a definitive agreement under which M&T will acquire People’s United in an all-stock transaction. Under the terms of the agreement, each share of People’s United common stock will be converted into the right to receive 0.118 shares of M&T common stock. The merger, which has been approved by the boards of directors and shareholders of each company, is expected to close promptly after the parties have satisfied customary closing conditions, including the approval of the Board of Governors of the Federal Reserve System (the “FRB”). Merger-related expenses totaling $22.3 million related to this transaction were recorded during the year ended December 31, 2021. Branch Consolidation On January 21, 2021, the Bank announced its decision not to renew its agreements with Stop & Shop to operate On August 5, 2021, the Bank announced it had reached an agreement with Stop & Shop to retain 27 in-store branch and corresponding ATM locations in Connecticut slated to close as part of the previously announced decision not to renew existing in-store branch contracts in Connecticut. The new agreement does not impact the previously announced exit period for all other Connecticut Stop & Shop branch locations. Closures are scheduled to occur over several years using a phased approach and begin in 2022. As of December 31, 2021, People’s United operated 111 Stop & Shop branch locations, 84 in Connecticut and 27 in New York. Contract termination costs recorded for the year ended December 31, 2021 totaled $24.2 million. Dispositions Completed in 2020 and 2019 Sale of People's United Insurance Agency On November 2, 2020, the Bank completed its sale of People's United Insurance Agency, Inc. (“PUIA”) to AssuredPartners in an all-cash transaction for $120 million. PUIA was a full-service insurance brokerage that provided commercial, personal and employee benefit insurance solutions. The assets sold totaled $58.5 million, consisting of cash and short-term receivables as well as related goodwill ($31.7 million) and other acquisition-related intangible assets (insurance customer relationships totaling $3.2 million). The liabilities sold totaled $14.4 million, consisting of short-term payables and other accrued expenses. Prior to the sale, the activities of PUIA were included in the Wealth Management operating segment which, for reporting purposes, was allocated among the Commercial Banking and Retail Banking reportable segments (see Note 25 for additional information). The sale resulted in a pre-tax gain, net of expenses, of $75.9 million, which is included in non-interest income in the Consolidated Statements of Income. Sale of Branches On October 25, 2019, the Bank completed the sale of eight branches located in central Maine, including approximately: (i) $103 million in loans; (ii) $258 million in deposits; and (iii) $227 million of assets under management. The sale resulted in a gain, net of expenses, of $7.6 million, which is included in other non-interest income in the Consolidated Statements of Income. Acquisitions Completed in 2019 United Financial Bancorp, Inc. Effective November 1, 2019, People’s United completed its acquisition of United Financial Bancorp, Inc. (“United Financial”) based in Hartford, Connecticut. The fair value of the consideration transferred in the United Financial acquisition totaled $720.6 million and consisted of 44.4 million shares of People’s United common stock. At the acquisition date, United Financial operated 58 branch locations concentrated in central Connecticut and western Massachusetts. The fair value of assets acquired and liabilities assumed in the United Financial acquisition totaled $7.22 billion and $6.50 billion, respectively. Merger-related expenses recorded during the years ended December 31, 2020 and 2019 related to this acquisition totaled $43.3 million and $22.2 million, respectively. BSB Bancorp, Inc. Effective April 1, 2019, People’s United completed its acquisition of BSB Bancorp, Inc. (“BSB Bancorp”) based in Belmont, Massachusetts. The fair value of the consideration transferred in the BSB Bancorp acquisition totaled $324.5 million and consisted of 19.7 million shares of People’s United common stock. At the acquisition date, BSB Bancorp operated VAR Technology Finance Effec tive January 2, 2019, the Bank completed its acquisition of VAR Technology Finance (“VAR”), a leasing and financing company headquartered in Mesquite, Texas. The fair value of the consideration transferred in the VAR acquisition consisted of $60.0 million in cash. Merger-related expenses totaling $1.9 million related to this transaction were recorded during the year ended December 31, 2019.

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	NOTE 3 – Cash and Cash Equivalents Included in short-term investments are interest-bearing deposits at the FRB-NY, which yielded 0.15% and 0.10% at December 31, 2021 and 2020, respectively, and represent an alternative to overnight federal funds sold. Short-term investments consist of the following cash equivalents: As of December 31 (in millions) 2021 2020 Interest-bearing deposits at the FRB-NY $ 10,180.8 $ 3,598.9 Collateral posted for derivative instruments 73.4 151.9 Money market mutual funds 14.1 8.9 Other 0.5 6.3 Total short-term investments $ 10,268.8 $ 3,766.0

Securities

Securities	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Securities	NOTE 4 – Securities The amortized cost, ACL, gross unrealized gains and losses, and fair value of People’s United’s debt securities As of December 31, 2021 (in millions) Amortized ACL Gross Gross Fair Debt securities available-for-sale: U.S. Treasury and agency $ 632.7 $ — $ 4.0 $ — $ 636.7 GSE mortgage-backed and CMO securities 6,055.2 — 51.7 (99.6) 6,007.3 Total debt securities available-for-sale $ 6,687.9 $ — $ 55.7 $ (99.6) $ 6,644.0 Debt securities held-to-maturity: State and municipal $ 2,865.2 $ (0.1) $ 180.4 $ (3.0) $ 3,042.5 GSE mortgage-backed securities 893.5 — 15.6 — 909.1 Corporate 82.8 (1.4) 1.7 (0.1) 83.0 Other 1.5 — — — 1.5 Total debt securities held-to-maturity $ 3,843.0 $ (1.5) $ 197.7 $ (3.1) $ 4,036.1 As of December 31, 2020 (in millions) Amortized ACL Gross Gross Fair Debt securities available-for-sale: U.S. Treasury and agency $ 529.8 $ — $ 11.8 $ — $ 541.6 GSE mortgage-backed and CMO securities 4,274.7 — 110.9 (1.7) 4,383.9 Total debt securities available-for-sale $ 4,804.5 $ — $ 122.7 $ (1.7) $ 4,925.5 Debt securities held-to-maturity: State and municipal $ 2,824.3 $ (0.1) $ 236.0 $ — $ 3,060.2 GSE mortgage-backed securities 1,079.9 — 36.4 — 1,116.3 Corporate 89.7 (1.5) 1.0 (0.2) 89.0 Other 1.5 — — — 1.5 Total debt securities held-to-maturity $ 3,995.4 $ (1.6) $ 273.4 $ (0.2) $ 4,267.0 At December 31, 2021 and 2020, accrued interest receivable associated with (i) debt securities available-for-sale totaling $12.6 million and $10.7 million, respectively, and (ii) debt securities held-to-maturity totaling $31.9 million and $31.5 million, respectively, is reported in other assets in the Consolidated Statements of Condition. At both December 31, 2021 and 2020, no debt securities held-to-maturity were past due or in non-accrual status. The following table summarizes changes in the ACL on debt securities held-to-maturity for the years ended December 31, 2021 and 2020: December 31, 2021 December 31, 2020 (in millions) Corporate State and municipal Total Corporate State and municipal Total Balance at beginning of period $ 1.5 $ 0.1 $ 1.6 $ — $ — $ — CECL transition adjustment — — — 1.8 0.1 1.9 Balance at beginning of period, adjusted 1.5 0.1 1.6 1.8 0.1 1.9 Provision charged (credited) to income (0.1) — (0.1) (0.3) — (0.3) Balance at end of period $ 1.4 $ 0.1 $ 1.5 $ 1.5 $ 0.1 $ 1.6 Credit Quality Indicators Credit ratings, which are updated monthly, are a key measure for estimating the probability of a bond's default and for monitoring credit quality on an on-going basis. For bonds other than U.S. Treasuries and bonds issued or guaranteed by U.S. government agencies, credit ratings issued by one or more nationally recognized statistical rating organizations such as Moody's, S&P, Fitch or Kroll are considered in conjunction with an assessment by the Company's risk management department. In the case of multiple ratings, generally the lower rating prevails. Investment grade reflects a credit rating of The tables below indicate the credit profile of the Company's debt securities held-to-maturity at amortized cost: As of December 31, 2021 (in millions) Investment Grade Non-Investment Grade Total State and municipal $ 2,865.0 $ 0.2 $ 2,865.2 GSE mortgage-backed securities 893.5 — 893.5 Corporate 77.8 5.0 82.8 Other 1.5 — 1.5 Total $ 3,837.8 $ 5.2 $ 3,843.0 As of December 31, 2020 (in millions) Investment Grade Non-Investment Grade Total State and municipal $ 2,824.1 $ 0.2 $ 2,824.3 GSE mortgage-backed securities 1,079.9 — 1,079.9 Corporate 84.7 5.0 89.7 Other 1.5 — 1.5 Total $ 3,990.2 $ 5.2 $ 3,995.4 The following tables summarize those debt securities available-for-sale with unrealized losses classified as to the length of time the losses have existed and, for which no ACL has been recognized. Certain unrealized losses totaled less than Continuous Unrealized Loss Position Less Than 12 Months 12 Months Or Longer Total As of December 31, 2021 (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Debt securities available-for-sale: GSE mortgage-backed and CMO $ 2,978.3 $ (55.2) $ 1,120.9 $ (44.4) $ 4,099.2 $ (99.6) U.S. Treasury and agency 15.1 — — — 15.1 — Total $ 2,993.4 $ (55.2) $ 1,120.9 $ (44.4) $ 4,114.3 $ (99.6) Continuous Unrealized Loss Position Less Than 12 Months 12 Months Or Longer Total As of December 31, 2020 (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Debt securities available-for-sale: GSE mortgage-backed and CMO $ 225.5 $ (1.7) $ — $ — $ 225.5 $ (1.7) Total $ 225.5 $ (1.7) $ — $ — $ 225.5 $ (1.7) At December 31, 2021, 172 (or approximately 42%) of the 412 debt securities available-for-sale owned by the Company had gross unrealized losses totaling $99.6 million. With respect to those securities with unrealized losses, all of the GSE mortgage-backed and CMO securities had AAA credit ratings and an average contractual maturity of 23 years. At both December 31, 2021 and 2020, no ACL had been recognized on debt securities available-for-sale in an unrealized loss position, as management does not believe any of the securities are impaired due to reasons of credit quality. Rather, the cause of the gross unrealized losses with respect to all of the debt securities is directly related to changes in interest rates. At this time, management does not intend to sell such securities nor is it more likely than not, based upon available evidence, that management will be required to sell such securities prior to recovery. No credit impairment losses were recognized in the Consolidated Statements of Income for the years ended December 31, 2021, 2020 and 2019. At December 31, 2021 and 2020, debt securities available-for-sale with fair values of $3.54 billion and $4.93 billion, respectively, and debt securities held-to-maturity with an amortized cost basis of $1.73 billion and $2.08 billion, respectively, were pledged as collateral for public deposits and for other purposes. The following table is a summary of the amortized cost, fair value and fully taxable equivalent (“FTE”) yield of debt securities as of December 31, 2021, based on remaining period to contractual maturity. Information for GSE mortgage-backed and CMO securities is based on the final contractual maturity dates without considering repayments and prepayments. The FTE yields on state and municipal securities were computed using a 24.6% tax rate. Available-for-Sale Held-to-Maturity (dollars in millions) Amortized Fair FTE Amortized Fair FTE U.S. Treasury and agency: Within 1 year $ 372.3 $ 374.9 1.36 % $ — $ — — % After 1 but within 5 years 260.4 261.8 1.34 — — — Total 632.7 636.7 1.35 — — — GSE mortgage-backed and CMO Within 1 year 17.0 17.0 3.15 43.9 44.2 2.21 After 1 but within 5 years 76.8 80.4 3.11 705.7 716.6 2.45 After 5 but within 10 years 1,448.7 1,458.8 1.96 143.9 148.3 2.23 After 10 years 4,512.7 4,451.1 1.56 — — — Total 6,055.2 6,007.3 1.68 893.5 909.1 2.40 State and municipal: Within 1 year — — — 43.8 44.3 3.06 After 1 but within 5 years — — — 220.9 228.4 2.84 After 5 but within 10 years — — — 802.6 859.9 3.70 After 10 years — — — 1,797.9 1,909.9 3.45 Total — — — 2,865.2 3,042.5 3.47 Corporate: Within 1 year — — — 1.0 1.0 2.67 After 1 but within 5 years — — — 11.8 11.8 2.60 After 5 but within 10 years — — — 70.0 70.2 4.66 Total — — — 82.8 83.0 4.34 Other: After 1 but within 5 years — — — 1.5 1.5 1.75 Total — — — 1.5 1.5 1.75 Total: Within 1 year 389.3 391.9 1.44 88.7 89.5 2.63 After 1 but within 5 years 337.2 342.2 1.74 939.9 958.3 2.54 After 5 but within 10 years 1,448.7 1,458.8 1.96 1,016.5 1,078.4 3.56 After 10 years 4,512.7 4,451.1 1.56 1,797.9 1,909.9 3.45 Total $ 6,687.9 $ 6,644.0 1.65 % $ 3,843.0 $ 4,036.1 3.24 % People’s United uses the specific identification method to determine the cost of securities sold and records securities transactions on the trade date. The components of net security gains (losses) are summarized below. Years ended December 31 (in millions) 2021 2020 2019 Debt securities: Gains $ 2.1 $ — $ 0.5 Losses (2.1) — (0.4) Total debt securities — — 0.1 Trading debt securities: Gains (1) — — 0.1 Losses — — — Total trading debt securities — — 0.1 Net security gains $ — $ — $ 0.2 (1) Gains on trading debt securities totaled less than $0.1 million for the year ended December 31, 2020 (none in 2021). Equity investments (other than equity method investments) are measured at fair value with changes in fair value recognized in net income. For the years ended December 31, 2021, 2020 and 2019, People’s United recorded unrealized (losses) gains of $(0.3) million, $(1.1) million and $1.5 million relating to the change in fair value of its equity securities during the respective periods (included in other non-interest income in the Consolidated Statements of Income). The Bank, as a member of the Federal Reserve Bank system, is currently required to purchase and hold shares of capital stock in the FRB-NY (total cost of $229.1 million and $228.4 million at December 31, 2021 and 2020, respectively) in an amount equal to 6% of its capital and surplus. Based on the current capital adequacy and liquidity position of the FRB-NY, management believes there is no impairment in the Company’s investment at December 31, 2021 and the cost of the investment approximates fair value. Dividend income on FRB-NY capital stock totaled $3.4 million, $2.0 million and $3.8 million for the years ended December 31, 2021, 2020 and 2019, respectively. The Bank, as a member of the FHLB of Boston, is currently required to purchase and hold shares of capital stock in the FHLB of Boston (total cost of $35.5 million and $38.2 million at December 31, 2021 and 2020, respectively) in an amount equal to its membership base investment plus an activity based investment determined according to the Bank’s level of outstanding FHLB advances. Based on the current capital adequacy and liquidity position of the FHLB of Boston, management believes there is no impairment in the Company’s investment at December 31, 2021 and the cost of the investment approximates fair value. Dividend income on FHLB capital stock totaled $0.6 million, $4.8 million and $7.0 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Loans

Loans	12 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
Loans	NOTE 5 – Loans People’s United has identified two loan portfolio segments, Commercial and Retail, which are comprised of the following loan classes: • Commercial Portfolio : commercial real estate; commercial and industrial; equipment financing; and MW/ABL. • Retail Portfolio : residential mortgage; home equity; and other consumer. The following table summarizes People’s United’s loans by loan portfolio segment and class: As of December 31 (in millions) 2021 2020 Commercial: Commercial real estate (1) $ 11,936.7 $ 13,336.9 Commercial and industrial (1) 8,747.6 10,764.1 Equipment financing 5,143.1 4,930.0 MW/ABL 3,304.5 4,218.2 Total Commercial Portfolio 29,131.9 33,249.2 Retail: Residential mortgage: Adjustable-rate 4,064.3 5,517.3 Fixed-rate 2,940.0 3,001.6 Total residential mortgage 7,004.3 8,518.9 Home equity and other consumer: Home equity 1,635.9 1,997.2 Other consumer 79.2 104.2 Total home equity and other consumer 1,715.1 2,101.4 Total Retail Portfolio 8,719.4 10,620.3 Total loans $ 37,851.3 $ 43,869.5 (1) In the first quarter of 2021, the Company completed a portfolio review to ensure consistent classification of certain commercial loans across the Company's franchise and conformity to industry practice for such loans. As a result, approximately $350 million of loans secured by non-owner-occupied commercial properties were prospectively reclassified, in March 2021, from commercial and industrial loans to commercial real estate loans. Prior period balances were not restated to conform to the current presentation. Paycheck Protection Program The CARES Act created a new loan guarantee program known as The Paycheck Protection Program (“PPP”), the objective of which is to provide small businesses with financial support to cover payroll and certain other qualifying expenses. The Consolidated Appropriations Act, 2021 , signed into law in December 2020, included additional funding for first and second draws of PPP loans up to March 31, 2021. In March 2021, The PPP Extension Act of 2021 was signed into law, extending the program to May 31, 2021. Loans made under the PPP are fully guaranteed by the Small Business Administration (the “SBA”), whose guarantee is backed by the full faith and credit of the United States. PPP loans also afford borrowers forgiveness up to the principal amount of the loan, plus accrued interest, provided the loan proceeds are used to retain workers and maintain payroll or to make certain mortgage interest, lease and utility payments, and certain other criteria are satisfied. The SBA will reimburse PPP lenders for any amount of a PPP loan that is forgiven, and PPP lenders will not be held liable for any representations made by PPP borrowers in connection with their requests for loan forgiveness. Included in commercial and industrial loans at December 31, 2021 and 2020 are PPP loans totaling $431.5 million and $2.3 billion, respectively, and associated deferred loan fees totaling $14.8 million and $45.9 million, respectively. For regulatory capital purposes, PPP loans are assigned a zero risk-weighting as a result of the related SBA guarantee. Net deferred loan costs, which are included in loans by respective class and exclude deferred fees on loans issued under the PPP, totaled $65.3 million at December 31, 2021 and $68.1 million at December 31, 2020. At December 31, 2021 and 2020, accrued interest receivable associated with loans reported in other assets in the Consolidated Statements of Condition totaled $122.7 million and $159.9 million, respectively. The Company wrote off accrued interest receivable attributable to the Commercial ($0.5 million and $1.3 million) and Retail ($0.1 million and $0.2 million) portfolio segments during the years ended December 31, 2021 and 2020, respectively. At December 31, 2021, 23%, 19% and 18% of the Company’s loans by outstanding principal amount were to customers located within Connecticut, Massachusetts and New York, respectively. Loans to customers located in the New England states as a group represented 53% and 55% of total loans at December 31, 2021 and 2020, respectively. Substantially the entire equipment financing portfolio (94% at both December 31, 2021 and 2020, respectively) was to customers located outside of New England. At December 31, 2021, 29% of the equipment financing portfolio was to customers located in Texas, California and New York, and no other state exposure was greater than 7%. Included in the Commercial portfolio are construction loans totaling $845.8 million and $1.2 billion at December 31, 2021 and 2020, respectively, net of the unadvanced portion of such loans totaling $365.4 million and $508.6 million, respectively. At December 31, 2021 and 2020, residential mortgage loans included $595.5 million and $866.4 million, respectively, of interest-only loans. People’s United’s underwriting guidelines and requirements for such loans are generally more restrictive than those applied to other types of residential mortgage products. Also included in residential mortgage loans are construction loans totaling $32.9 million and $44.8 million at December 31, 2021 and 2020, respectively, net of the unadvanced portion of such loans totaling $11.9 million and $7.2 million, respectively. People’s United sells newly-originated residential mortgage loans in the secondary market, without recourse. Net gains on sales of residential mortgage loans (included in other non-interest income in the Consolidated Statements of Income) totaled $1.6 million, $4.8 million and $1.9 million for the years ended December 31, 2021, 2020 and 2019, respectively. Loans The following tables summarize aging information by class of loan: Past Due As of December 31, 2021 (in millions) Current 30-89 90 Days Total Total Commercial: Commercial real estate $ 11,874.4 $ 6.7 $ 55.6 $ 62.3 $ 11,936.7 Commercial and industrial 8,717.5 13.4 16.7 30.1 8,747.6 Equipment financing 5,080.0 48.3 14.8 63.1 5,143.1 MW/ABL 3,304.5 — — — 3,304.5 Total 28,976.4 68.4 87.1 155.5 29,131.9 Retail: Residential mortgage 6,959.2 22.2 22.9 45.1 7,004.3 Home equity 1,620.8 8.0 7.1 15.1 1,635.9 Other consumer 78.7 0.4 0.1 0.5 79.2 Total 8,658.7 30.6 30.1 60.7 8,719.4 Total loans $ 37,635.1 $ 99.0 $ 117.2 $ 216.2 $ 37,851.3 Included in the “Current” and “30-89 Days” categories above are early non-performing commercial real estate loans, commercial and industrial loans, equipment financing loans and MW/ABL loans totaling $49.2 million, $29.3 million, Past Due As of December 31, 2020 (in millions) Current 30-89 90 Days Total Total Commercial: Commercial real estate $ 13,283.2 $ 27.3 $ 26.4 $ 53.7 $ 13,336.9 Commercial and industrial 10,694.9 17.3 51.9 69.2 10,764.1 Equipment financing 4,846.8 64.0 19.2 83.2 4,930.0 MW/ABL 4,218.2 — — — 4,218.2 Total 33,043.1 108.6 97.5 206.1 33,249.2 Retail: Residential mortgage 8,447.9 32.2 38.8 71.0 8,518.9 Home equity 1,977.3 8.4 11.5 19.9 1,997.2 Other consumer 103.4 0.7 0.1 0.8 104.2 Total 10,528.6 41.3 50.4 91.7 10,620.3 Total loans $ 43,571.7 $ 149.9 $ 147.9 $ 297.8 $ 43,869.5 Included in the “Current” and “30-89 Days” categories above are early non-performing commercial real estate loans, commercial and industrial loans, equipment financing loans and MW/ABL loans totaling $34.0 million, $26.0 million, $90.1 million and $1.0 million, respectively, and $32.6 million of retail loans in the process of foreclosure or bankruptcy. The recorded investment in non-accrual loans, by class of loan and year of origination, is summarized as follows: Non-Accrual Loans As of December 31, 2021 (in millions) 2021 2020 2019 2018 2017 Prior Revolving Loans Revolving Loans Converted to Term Total Non-Accrual Loans With No ACL Commercial: Commercial real estate $ — $ — $ 10.9 $ 24.6 $ 4.9 $ 64.2 $ — $ 0.2 $ 104.8 $ 42.9 Commercial and industrial 0.3 0.1 5.3 1.0 4.5 16.5 2.7 12.7 43.1 11.3 Equipment financing 1.3 14.0 21.4 17.3 18.5 10.8 — — 83.3 2.2 MW/ABL — — — — — — — 0.8 0.8 — Total (1) 1.6 14.1 37.6 42.9 27.9 91.5 2.7 13.7 232.0 56.4 Retail: Residential mortgage — 0.2 1.8 4.3 1.3 34.2 — — 41.8 14.8 Home equity — 0.1 — 0.4 0.1 2.3 — 11.7 14.6 4.8 Other consumer — — 0.1 — — — — — 0.1 — Total (2) — 0.3 1.9 4.7 1.4 36.5 — 11.7 56.5 19.6 Total $ 1.6 $ 14.4 $ 39.5 $ 47.6 $ 29.3 $ 128.0 $ 2.7 $ 25.4 $ 288.5 $ 76.0 Non-Accrual Loans As of December 31, 2020 (in millions) 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Non-Accrual Loans With No ACL Commercial: Commercial real estate $ — $ 8.6 $ 9.7 $ 2.8 $ 1.9 $ 35.4 $ 0.2 $ 1.8 $ 60.4 $ 10.9 Commercial and industrial 0.2 3.1 2.3 16.2 13.4 17.5 15.5 7.2 75.4 27.8 Equipment financing 16.4 27.4 25.3 25.5 7.8 6.9 — — 109.3 0.6 MW/ABL — — — — — — — 1.0 1.0 — Total (1) 16.6 39.1 37.3 44.5 23.1 59.8 15.7 10.0 246.1 39.3 Retail: Residential mortgage — 2.9 3.9 1.8 2.6 51.1 — — 62.3 28.3 Home equity — — 0.4 0.1 0.6 2.8 — 16.6 20.5 7.9 Other consumer — 0.1 — 0.1 — — — — 0.2 — Total (2) — 3.0 4.3 2.0 3.2 53.9 — 16.6 83.0 36.2 Total $ 16.6 $ 42.1 $ 41.6 $ 46.5 $ 26.3 $ 113.7 $ 15.7 $ 26.6 $ 329.1 $ 75.5 As of December 31 (in millions) 2019 Commercial: Commercial real estate $ 53.8 Commercial and industrial 38.5 Equipment financing 47.7 Total (1) 140.0 Retail: Residential mortgage 63.3 Home equity 20.8 Other consumer — Total (2) 84.1 Total $ 224.1 (1) Reported net of government guarantees totaling $2.9 million, $2.5 million and $1.3 million at December 31, 2021, 2020 and 2019, respectively. These government guarantees relate, almost entirely, to guarantees provided by the SBA as well as selected other Federal agencies and represent the carrying value of the loans that are covered by such guarantees, the extent of which (i.e. full or partial) varies by loan. At December 31, 2021, 100% of the government guarantees relate to commercial and industrial loans. (2) Includes $12.3 million, $23.6 million and $17.0 million of loans in the process of foreclosure at December 31, 2021, 2020 and 2019, respectively. Interest income recognized on non-accrual loans totaled $2.0 million, $4.1 million and $2.3 million for the years ended December 31, 2021, 2020 and 2019, respectively. At December 31, 2021 and 2020, the Company had collateral dependent commercial loans totaling $79.8 million and $71.1 million, respectively, and collateral dependent residential mortgage and home equity loans totaling $21.0 million and $37.8 million, respectively. The Company's collateral dependent loans primarily relate to loans in the commercial and industrial, commercial real estate and residential mortgage portfolios. The extent to which collateral secures such loans is greatest within the residential mortgage portfolio. At December 31, 2021 and 2020, People’s United’s recorded investment in loans classified as TDRs totaled $303.2 million and $196.9 million, respectively, and the related ACL was $18.4 million and $12.0 million at the respective dates. Interest income recognized on TDRs totaled $6.1 million, $4.6 million and $5.5 million for the years ended December 31, 2021, 2020 and 2019, respectively. Fundings under commitments to lend additional amounts to borrowers with loans classified as TDRs were immaterial for the years ended December 31, 2021, 2020 and 2019. Loans that were modified and classified as TDRs during 2021 principally involve reduced payment and/or payment deferral, extension of term (generally no more than three years for commercial loans and ten years for retail loans) and/or a temporary reduction of interest rate (generally less than 200 basis points). The following tables summarize, by class of loan, the recorded investments in loans modified as TDRs during the years ended December 31, 2021 and 2020. For purposes of this disclosure, recorded investments represent amounts immediately prior to and subsequent to the restructuring. Year ended December 31, 2021 (dollars in millions) Number of Pre-Modification Post-Modification Commercial: Commercial real estate (1) 18 $ 74.1 $ 74.1 Commercial and industrial (2) 25 26.7 26.7 Equipment financing (3) 19 3.8 3.8 MW/ABL (4) 2 3.0 3.0 Total 64 107.6 107.6 Retail: Residential mortgage (5) 55 17.0 17.0 Home equity (6) 69 4.8 4.8 Other consumer — — — Total 124 21.8 21.8 Total 188 $ 129.4 $ 129.4 (1) Represents the following concessions: extension of term (10 contracts; recorded investment of $14.9 million); reduced payment and/or payment deferral (4 contracts; recorded investment of $37.8 million); or a combination of concessions (2) Represents the following concessions: extension of term (18 contracts; recorded investment of $16.8 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $4.6 million); or a combination of concessions (3) Represents the following concessions: extension of term (11 contracts; recorded investment of $0.9 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $1.5 million); or a combination of concessions (4) Represents the following concessions: extension of term (2 contracts; recorded investment of $3.0 million). (5) Represents the following concessions: loans restructured through bankruptcy (12 contracts; recorded investment of $1.8 million); extension of term (1 contract; recorded investment of $2.0 million); reduced payment and/or payment deferral (29 contracts; recorded investment of $8.6 million); or a combination of concessions (13 contracts; recorded investment of $4.6 million). (6) Represents the following concessions: loans restructured through bankruptcy (13 contracts; recorded investment of $1.4 million); extension of term (4 contracts; recorded investment of $0.2 million); reduced payment and/or payment deferral (13 contracts; recorded investment of $0.8 million); or a combination of concessions (39 contracts; recorded investment of $2.4 million). Year ended December 31, 2020 (dollars in millions) Number of Pre-Modification Post-Modification Commercial: Commercial real estate (1) 18 $ 16.7 $ 16.7 Commercial and industrial (2) 44 71.5 71.5 Equipment financing (3) 43 14.4 14.4 MW/ABL (4) 9 7.6 7.6 Total 114 110.2 110.2 Retail: Residential mortgage (5) 38 16.3 16.3 Home equity (6) 50 5.7 5.7 Other consumer — — — Total 88 22.0 22.0 Total 202 $ 132.2 $ 132.2 (1) Represents the following concessions: extension of term (13 contracts; recorded investment of $8.3 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $3.9 million); temporary rate reduction (1 contract; recorded investment of $0.4 million); or a combination of concessions (2 contracts; recorded investment of $4.1 million). (2) Represents the following concessions: extension of term (23 contracts; recorded investment of $30.0 million); reduced payment and/or payment deferral (10 contracts; recorded investment of $36.7 million); temporary rate reduction (3) Represents the following concessions: extension of term (21 contracts; recorded investment of $5.2 million); reduced payment and/or payment deferral (13 contracts; recorded investment of $3.4 million); or a combination of concessions (4) Represents the following concessions: extension of term (9 contracts; recorded investment of $7.6 million). (5) Represents the following concessions: loans restructured through bankruptcy (10 contracts; recorded investment of $2.4 million); reduced payment and/or payment deferral (12 contracts; recorded investment of $7.3 million); or a combination of concessions (16 contracts; recorded investment of $6.6 million). (6) Represents the following concessions: loans restructured through bankruptcy (19 contracts; recorded investment of $1.5 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $0.2 million); or a combination of concessions (29 contracts; recorded investment of $4.0 million). The following is a summary, by class of loan, of information related to TDRs completed within the previous 12 months that subsequently defaulted during the years ended December 31, 2021 and 2020. For purposes of this disclosure, the previous 12 months is measured from January 1 of the respective prior year and a default represents a previously-modified loan that became past due 30 days or more during 2021 or 2020. 2021 2020 Years ended December 31 (dollars in millions) Number of Recorded Number of Recorded Commercial: Commercial real estate — $ — 2 $ 1.5 Commercial and industrial 1 1.2 8 4.7 Equipment financing 8 0.3 9 1.7 MW/ABL — — — — Total 9 1.5 19 7.9 Retail: Residential mortgage 6 2.8 2 0.1 Home equity 8 0.4 — — Other consumer — — — — Total 14 3.2 2 0.1 Total 23 $ 4.7 21 $ 8.0 Credit Quality Indicators As part of the on-going monitoring of the credit quality of the loan portfolio, management tracks certain credit quality indicators, including trends related to: (i) internal Commercial loan risk ratings; (ii) internal Retail loan risk classification; and (iii) non-accrual loans (see Note 1). Commercial Credit Quality Indicators The Company utilizes an internal loan risk rating system as a means of monitoring portfolio credit quality and identifying both problem and potential problem loans. Under the Company’s risk rating system, loans not meeting the criteria for problem and potential problem loans as specified below are considered to be “Pass”-rated loans. Problem and potential problem loans are classified as either “Special Mention,” “Substandard” or “Doubtful.” Loans that do not currently expose the Company to sufficient enough risk of loss to warrant classification as either Substandard or Doubtful, but possess weaknesses that deserve management’s close attention, are classified as Special Mention. Substandard loans represent those credits characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. Loans classified as Doubtful possess all the weaknesses inherent in those classified Substandard with the added characteristic that collection or liquidation in full, on the basis of existing facts, conditions and values, is highly questionable and/or improbable. Risk ratings on commercial loans are subject to ongoing monitoring by lending and credit personnel with such ratings updated annually or more frequently, if warranted. The Company’s internal Loan Review function is responsible for independently evaluating the appropriateness of those credit risk ratings in connection with its cyclical reviews, the approach to which is risk-based and determined by reference to underlying portfolio credit quality and the results of prior reviews. Differences in risk ratings noted in conjunction with such periodic portfolio loan reviews, if any, are reported to management each month. The following tables present Commercial loan risk ratings, by class of loan and year of origination: As of December 31, 2021 (in millions) 2021 2020 2019 2018 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial real Pass $ 508.3 $ 916.4 $ 1,701.0 $ 1,177.7 $ 968.2 $ 4,796.2 $ 136.1 $ 32.9 $ 10,236.8 Special Mention 18.4 73.8 124.1 129.7 118.4 342.7 — 0.4 807.5 Substandard 3.3 11.3 112.5 149.7 106.6 506.2 1.5 0.2 891.3 Doubtful — — — 0.1 — 1.0 — — 1.1 Total $ 530.0 $ 1,001.5 $ 1,937.6 $ 1,457.2 $ 1,193.2 $ 5,646.1 $ 137.6 $ 33.5 $ 11,936.7 Commercial and Pass $ 1,646.7 $ 656.3 $ 834.3 $ 538.7 $ 445.9 $ 1,517.6 $ 2,475.4 $ 47.0 $ 8,161.9 Special Mention 2.2 2.9 19.3 10.9 41.5 81.6 24.7 8.4 191.5 Substandard 11.0 17.5 40.7 30.5 85.7 134.5 54.6 18.9 393.4 Doubtful — — 0.3 — — 0.5 — — 0.8 Total $ 1,659.9 $ 676.7 $ 894.6 $ 580.1 $ 573.1 $ 1,734.2 $ 2,554.7 $ 74.3 $ 8,747.6 Equipment financing: Pass $ 2,005.1 $ 1,151.2 $ 847.7 $ 390.6 $ 157.7 $ 78.5 $ — $ — $ 4,630.8 Special Mention 27.5 8.4 14.4 5.9 8.0 2.5 — — 66.7 Substandard 150.6 110.7 94.4 48.4 27.1 14.4 — — 445.6 Doubtful — — — — — — — — — Total $ 2,183.2 $ 1,270.3 $ 956.5 $ 444.9 $ 192.8 $ 95.4 $ — $ — $ 5,143.1 MW/ABL: Pass $ 44.7 $ 13.8 $ 15.0 $ 10.2 $ 3.1 $ 25.7 $ 3,147.8 $ — $ 3,260.3 Special Mention — — — — — — 12.6 — 12.6 Substandard — — — — — — 30.8 0.8 31.6 Doubtful — — — — — — — — — Total $ 44.7 $ 13.8 $ 15.0 $ 10.2 $ 3.1 $ 25.7 $ 3,191.2 $ 0.8 $ 3,304.5 As of December 31, 2020 (in millions) 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial real Pass $ 848.5 $ 1,743.2 $ 1,490.4 $ 1,397.8 $ 1,274.2 $ 5,039.3 $ 165.8 $ 19.7 $ 11,978.9 Special Mention 28.5 72.9 225.6 131.2 58.9 362.7 0.5 — 880.3 Substandard 12.0 26.7 63.3 51.9 63.2 252.7 2.8 4.2 476.8 Doubtful — — — — — 0.9 — — 0.9 Total $ 889.0 $ 1,842.8 $ 1,779.3 $ 1,580.9 $ 1,396.3 $ 5,655.6 $ 169.1 $ 23.9 $ 13,336.9 Commercial and Pass $ 2,952.8 $ 1,236.9 $ 821.9 $ 527.1 $ 487.2 $ 1,588.5 $ 1,949.1 $ 77.4 $ 9,640.9 Special Mention 113.9 41.7 46.4 120.3 57.1 122.1 80.8 6.3 588.6 Substandard 27.0 86.3 84.2 47.6 29.8 141.2 97.7 18.4 532.2 Doubtful — — — — 0.8 1.5 — 0.1 2.4 Total $ 3,093.7 $ 1,364.9 $ 952.5 $ 695.0 $ 574.9 $ 1,853.3 $ 2,127.6 $ 102.2 $ 10,764.1 Equipment financing: Pass $ 1,703.3 $ 1,358.7 $ 727.2 $ 362.1 $ 155.5 $ 67.1 $ — $ — $ 4,373.9 Special Mention 20.5 27.5 16.7 7.3 4.2 1.5 — — 77.7 Substandard 169.9 137.5 87.7 49.8 17.9 15.6 — — 478.4 Doubtful — — — — — — — — — Total $ 1,893.7 $ 1,523.7 $ 831.6 $ 419.2 $ 177.6 $ 84.2 $ — $ — $ 4,930.0 MW/ABL: Pass $ 99.4 $ 18.6 $ 18.3 $ 8.8 $ 14.1 $ 19.6 $ 3,994.3 $ — $ 4,173.1 Special Mention — 6.9 — — — — 20.5 — 27.4 Substandard — 1.7 — — — — 15.0 1.0 17.7 Doubtful — — — — — — — — — Total $ 99.4 $ 27.2 $ 18.3 $ 8.8 $ 14.1 $ 19.6 $ 4,029.8 $ 1.0 $ 4,218.2 Retail Credit Quality Indicators Pools of Retail loans with similar risk and loss characteristics are also assessed for losses. These loan pools include residential mortgage, home equity and other consumer loans that are not assigned individual loan risk ratings. Rather, the assessment of these portfolios is based upon a consideration of recent historical loss experience, broader portfolio indicators, including trends in delinquencies, non-accrual loans and portfolio concentrations, and portfolio-specific risk characteristics, the combination of which determines whether a loan is classified as “High”, “Moderate” or “Low” risk. The portfolio-specific risk characteristics considered include: (i) collateral values/LTV ratios (above and below 70%); For example, to the extent LTV ratios exceed 70% (reflecting a weaker collateral position for the Company) or borrower FICO scores are less than 680 (reflecting weaker financial standing and/or credit history of the customer), the loans are considered to have an increased level of inherent loss. As a result, a loan with a combination of these characteristics would generally be classified as “High” risk. Conversely, as LTV ratios decline (reflecting a stronger collateral position for the Company) or borrower FICO scores exceed 680 (reflecting stronger financial standing and/or credit history of the customer), the loans are considered to have a decreased level of inherent loss. A loan with a combination of these characteristics would generally be classified as “Low” risk. This analysis also considers (i) the extent of underwriting that occurred at the time of origination (direct income verification provides further support for credit decisions) and (ii) the property’s intended use LTV ratios and FICO scores are determined at origination and updated periodically throughout the life of the loan. LTV ratios are updated for loans 90 days past due and FICO scores are updated for the entire portfolio quarterly. The portfolio stratification (“High”, “Moderate” and “Low” risk) and identification of the corresponding credit quality indicators also occurs quarterly. The following tables present Retail loan risk classifications, by class of loan and year of origination: As of December 31, 2021 (in millions) 2021 2020 2019 2018 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Residential mortgage: Low Risk $ 753.4 $ 643.0 $ 277.0 $ 208.8 $ 321.4 $ 1,922.9 $ — $ — $ 4,126.5 Moderate Risk 567.1 602.8 243.7 215.6 253.3 463.1 — — 2,345.6 High Risk 62.0 53.5 36.8 56.3 73.3 250.3 — — 532.2 Total $ 1,382.5 $ 1,299.3 $ 557.5 $ 480.7 $ 648.0 $ 2,636.3 $ — $ — $ 7,004.3 Home equity: Low Risk $ 2.4 $ 2.4 $ 8.2 $ 24.2 $ 22.7 $ 29.2 $ 538.1 $ 44.4 $ 671.6 Moderate Risk 0.7 0.8 4.1 12.0 11.6 15.5 416.4 43.3 504.4 High Risk 0.4 0.6 9.4 8.9 5.4 13.6 308.4 113.2 459.9 Total $ 3.5 $ 3.8 $ 21.7 $ 45.1 $ 39.7 $ 58.3 $ 1,262.9 $ 200.9 $ 1,635.9 Other consumer: Low Risk $ 1.2 $ 0.5 $ 1.4 $ 1.3 $ 0.8 $ 2.6 $ 18.0 $ 1.2 $ 27.0 Moderate Risk — — — — — — 4.0 0.1 4.1 High Risk 4.7 2.4 11.8 7.0 0.7 5.1 15.5 0.9 48.1 Total $ 5.9 $ 2.9 $ 13.2 $ 8.3 $ 1.5 $ 7.7 $ 37.5 $ 2.2 $ 79.2 As of December 31, 2020 (in millions) 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Residential mortgage: Low Risk $ 609.5 $ 349.1 $ 338.3 $ 504.0 $ 1,004.6 $ 1,793.8 $ — $ — $ 4,599.3 Moderate Risk 752.5 456.8 443.9 517.5 520.2 519.8 — — 3,210.7 High Risk 81.2 60.4 95.0 109.6 86.6 276.1 — — 708.9 Total $ 1,443.2 $ 866.3 $ 877.2 $ 1,131.1 $ 1,611.4 $ 2,589.7 $ — $ — $ 8,518.9 Home equity: Low Risk $ 1.9 $ 7.4 $ 21.1 $ 24.6 $ 10.7 $ 25.8 $ 580.0 $ 42.9 $ 714.4 Moderate Risk 0.6 3.7 9.2 12.2 6.6 13.4 520.0 45.3 611.0 High Risk 2.8 21.8 38.1 22.0 7.5 18.8 415.7 145.1 671.8 Total $ 5.3 $ 32.9 $ 68.4 $ 58.8 $ 24.8 $ 58.0 $ 1,515.7 $ 233.3 $ 1,997.2 Other consumer: Low Risk $ 0.9 $ 1.7 $ 1.7 $ 0.9 $ 0.4 $ 2.7 $ 11.4 $ 0.1 $ 19.8 Moderate Risk — — — — — 0.1 4.8 0.1 5.0 High Risk 5.5 27.3 17.9 2.3 1.0 8.5 16.8 0.1 79.4 Total $ 6.4 $ 29.0 $ 19.6 $ 3.2 $ 1.4 $ 11.3 $ 33.0 $ 0.3 $ 104.2 The following table is a summary of revolving loans that converted to term during the years ended December 31, 2021 and 2020: Years ended December 31 (in millions) 2021 2020 Commercial: Commercial real estate $ 15.3 $ 1.4 Commercial and industrial 25.1 53.3 Equipment financing — — MW/ABL — — Total 40.4 54.7 Retail: Residential mortgage — — Home equity 39.3 37.1 Other consumer 1.2 0.1 Total 40.5 37.2 Total $ 80.9 $ 91.9

Allowance For Credit Losses

Allowance For Credit Losses	12 Months Ended
	Dec. 31, 2021
Allowance for Credit Loss [Abstract]
Allowance for Credit Losses	NOTE 6 – Allowance for Credit Losses Allowance for Credit Losses – Loans At December 31, 2021 and 2020, the collective ACL totaled $330.0 million and $404.6 million, respectively, and the specific allocations of the ACL for loans evaluated on an individual basis totaled $13.6 million and $20.5 million, respectively. The increase in the ACL in 2020 primarily reflects the initial application of the CECL standard and the economic uncertainties brought about by COVID-19, specifically as it relates to assumptions regarding GDP and unemployment. The following table presents a summary, by loan portfolio segment, of activity in the ACL for the years ended December 31, 2021, 2020 and 2019: 2021 2020 2019 Years ended December 31 Commercial Retail Total Commercial Retail Total Commercial Retail Total Balance at beginning $ 303.6 $ 121.5 $ 425.1 $ 217.9 $ 28.7 $ 246.6 $ 209.5 $ 30.9 $ 240.4 CECL transition adjustment — — — (17.3) 89.5 72.2 — — — Balance at beginning 303.6 121.5 425.1 200.6 118.2 318.8 209.5 30.9 240.4 Charge-offs (48.3) (3.1) (51.4) (52.4) (6.5) (58.9) (27.5) (4.0) (31.5) Recoveries 12.8 5.3 18.1 6.4 2.7 9.1 6.3 3.1 9.4 Net loan (35.5) 2.2 (33.3) (46.0) (3.8) (49.8) (21.2) (0.9) (22.1) Provision for credit (66.5) 18.3 (48.2) 149.0 7.1 156.1 29.6 (1.3) 28.3 Balance at end $ 201.6 $ 142.0 $ 343.6 $ 303.6 $ 121.5 $ 425.1 $ 217.9 $ 28.7 $ 246.6 Allowance for Credit Losses – Off-Balance-Sheet Credit Exposures The following table summarizes changes in the ACL on off-balance-sheet credit exposures for the years ended December 31, 2021, 2020 and 2019: Years ended December 31 (in millions) 2021 2020 2019 Balance at beginning of period $ 26.9 $ 5.6 $ 2.7 CECL transition adjustment — 14.5 — Balance at beginning of period, adjusted 26.9 20.1 2.7 Provision charged (credited) to income 1.5 6.8 2.9 Balance at end of period $ 28.4 $ 26.9 $ 5.6

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	NOTE 7 – Leases Lessor Arrangements People's United provides equipment financing to its customers through a variety of lessor arrangements, some of which may include options to renew and/or for the lessee to purchase the leased equipment at the end of the lease term. Direct financing leases and sales-type leases (collectively, “lease financing receivables”) are carried at the aggregate of lease payments receivable plus the estimated residual value of the leased assets and any initial direct costs incurred to originate these leases , less unearned income, which is accreted to interest income over the lease term using the interest method. The residual value component of a lease financing receivable represents the estimated fair value of the leased equipment at the end of the lease term. In establishing residual value estimates, the Company may rely on industry data, historical experience, independent appraisals and, where appropriate, information regarding product life cycle, product upgrades and competing products. Upon expiration of a lease, residual assets are remarketed, resulting in an extension of the lease by the lessee, a lease to a new customer or purchase of the residual asset by the lessee or another party. Impairment of residual values arises if the expected fair value is less than the carrying amount. The Company assesses its net investment in lease financing receivables (including residual values) for impairment on a quarterly basis with any impairment losses recognized in accordance with the impairment guidance for financial instruments. As such, net investment in lease financing receivables may be reduced by an ACL with changes recognized as provision expense. The composition of the Company’s total net investment in lease financing receivables included within equipment financing loans in the Consolidated Statements of Condition was as follows: As of December 31 (in millions) 2021 2020 Lease payments receivable $ 1,368.3 $ 1,418.4 Estimated residual value of leased assets 130.1 132.7 Gross investment in lease financing receivables 1,498.4 1,551.1 Plus: Deferred origination costs 10.2 11.6 Less: Unearned income (140.4) (150.7) Total net investment in lease financing receivables $ 1,368.2 $ 1,412.0 The contractual maturities of the Company's lease financing receivables were as follows: (in millions) December 31, 2021 2022 $ 532.9 2023 402.6 2024 292.0 2025 172.3 2026 83.0 Later years 15.6 Total $ 1,498.4 Operating lease income, generated in connection with operating leases for which the Company acts as a lessor, is recognized on a straight-line basis over the lease term as a component of non-interest income in the Consolidated Statements of Income. Depreciation expense for assets under operating leases, which are included in other assets in the Consolidated Statements of Condition, is generally recorded on a straight-line basis over the lease term as a component of non-interest expense in the Consolidated Statements of Income. The following table summarizes People's United's total lease income for the years ended December 31, 2021, 2020 and 2019: Years ended December 31 (in millions) 2021 2020 2019 Lease financing receivables $ 66.3 $ 69.0 $ 66.7 Operating leases 44.7 49.7 50.8 Total lease income $ 111.0 $ 118.7 $ 117.5 Lessee Arrangements Substantially all of the Company’s lessee arrangements represent non-cancelable operating leases for real estate (primarily branch locations) and office equipment with terms extending through 2054. Under these arrangements, People's United records right-of-use (“ROU”) assets and corresponding lease liabilities at lease commencement. Lease liabilities are recognized based on the present value of the remaining lease payments and discounted using the Company’s incremental borrowing rate for borrowings of similar term. ROU assets initially equal the related lease liability, adjusted for any lease payments made prior to the lease commencement and any lease incentives. Portions of certain properties are subleased for terms extending through 2038. At lease commencement, the Company considers renewal or termination options in the determination of the term of the lease. If it is reasonably certain that a renewal or termination option will be exercised, the effects of such options are included in the determination of the expected lease term. All leases are recorded with the exception of leases with an initial term of twelve months or less for which the Company made the short-term lease election. Within the Consolidated Statements of Condition, ROU assets are reported in other assets and the related lease liabilities are reported in other liabilities. In recognizing ROU assets and related lease liabilities, lease and non-lease components (such as taxes, insurance and common area maintenance costs) are accounted for separately as such amounts are generally readily determinable under the Company's lease contracts. Lease expense is recognized on a straight-line basis over the lease term and is recorded within occupancy and equipment expense in the Consolidated Statements of Income. Variable lease payments, which generally relate to the non-lease components noted above, are expensed as incurred. The following tables provide the components of lease cost and supplemental information: Years ended December 31 (in millions) 2021 2020 2019 Operating lease cost $ 63.0 $ 65.1 $ 61.6 Variable lease cost 9.8 10.0 8.6 Finance lease cost 0.3 0.3 0.1 Sublease income (2.2) (1.9) (1.4) Net lease cost $ 70.9 $ 73.5 $ 68.9 As of December 31 (dollars in millions) 2021 2020 Lease ROU assets: Operating lease $ 210.6 $ 234.9 Finance lease 2.1 2.3 Lease liabilities: Operating lease 242.0 270.4 Finance lease 4.5 4.9 Weighted-average discount rate: Operating leases 2.86 % 3.08 % Finance leases 2.59 2.59 Weighted-average remaining lease term (in years): Operating leases 7.2 7.6 Finance leases 10.3 11.2 Years ended December 31 (dollars in millions) 2021 2020 2019 Cash payments included in the measurement of lease liabilities: Reported in operating cash from operating leases $ 68.6 $ 66.6 $ 61.7 Reported in financing cash from finance leases 0.1 0.1 0.1 ROU assets obtained in exchange for lessee: Operating lease liabilities 31.4 22.8 89.1 Finance lease liabilities — — 2.6 The contractual maturities of the Company's lease liabilities as of December 31, 2021 were as follows: (in millions) Operating Leases Finance Leases 2022 $ 55.6 $ 0.5 2023 44.2 0.5 2024 38.8 0.5 2025 34.7 0.5 2026 24.5 0.5 Later years 74.1 2.6 Total lease payments 271.9 5.1 Less: Interest (29.9) (0.6) Total lease liabilities $ 242.0 $ 4.5 In the third quarter of 2021, the Company completed two sale-leaseback transactions on properties located in
Leases	NOTE 7 – Leases Lessor Arrangements People's United provides equipment financing to its customers through a variety of lessor arrangements, some of which may include options to renew and/or for the lessee to purchase the leased equipment at the end of the lease term. Direct financing leases and sales-type leases (collectively, “lease financing receivables”) are carried at the aggregate of lease payments receivable plus the estimated residual value of the leased assets and any initial direct costs incurred to originate these leases , less unearned income, which is accreted to interest income over the lease term using the interest method. The residual value component of a lease financing receivable represents the estimated fair value of the leased equipment at the end of the lease term. In establishing residual value estimates, the Company may rely on industry data, historical experience, independent appraisals and, where appropriate, information regarding product life cycle, product upgrades and competing products. Upon expiration of a lease, residual assets are remarketed, resulting in an extension of the lease by the lessee, a lease to a new customer or purchase of the residual asset by the lessee or another party. Impairment of residual values arises if the expected fair value is less than the carrying amount. The Company assesses its net investment in lease financing receivables (including residual values) for impairment on a quarterly basis with any impairment losses recognized in accordance with the impairment guidance for financial instruments. As such, net investment in lease financing receivables may be reduced by an ACL with changes recognized as provision expense. The composition of the Company’s total net investment in lease financing receivables included within equipment financing loans in the Consolidated Statements of Condition was as follows: As of December 31 (in millions) 2021 2020 Lease payments receivable $ 1,368.3 $ 1,418.4 Estimated residual value of leased assets 130.1 132.7 Gross investment in lease financing receivables 1,498.4 1,551.1 Plus: Deferred origination costs 10.2 11.6 Less: Unearned income (140.4) (150.7) Total net investment in lease financing receivables $ 1,368.2 $ 1,412.0 The contractual maturities of the Company's lease financing receivables were as follows: (in millions) December 31, 2021 2022 $ 532.9 2023 402.6 2024 292.0 2025 172.3 2026 83.0 Later years 15.6 Total $ 1,498.4 Operating lease income, generated in connection with operating leases for which the Company acts as a lessor, is recognized on a straight-line basis over the lease term as a component of non-interest income in the Consolidated Statements of Income. Depreciation expense for assets under operating leases, which are included in other assets in the Consolidated Statements of Condition, is generally recorded on a straight-line basis over the lease term as a component of non-interest expense in the Consolidated Statements of Income. The following table summarizes People's United's total lease income for the years ended December 31, 2021, 2020 and 2019: Years ended December 31 (in millions) 2021 2020 2019 Lease financing receivables $ 66.3 $ 69.0 $ 66.7 Operating leases 44.7 49.7 50.8 Total lease income $ 111.0 $ 118.7 $ 117.5 Lessee Arrangements Substantially all of the Company’s lessee arrangements represent non-cancelable operating leases for real estate (primarily branch locations) and office equipment with terms extending through 2054. Under these arrangements, People's United records right-of-use (“ROU”) assets and corresponding lease liabilities at lease commencement. Lease liabilities are recognized based on the present value of the remaining lease payments and discounted using the Company’s incremental borrowing rate for borrowings of similar term. ROU assets initially equal the related lease liability, adjusted for any lease payments made prior to the lease commencement and any lease incentives. Portions of certain properties are subleased for terms extending through 2038. At lease commencement, the Company considers renewal or termination options in the determination of the term of the lease. If it is reasonably certain that a renewal or termination option will be exercised, the effects of such options are included in the determination of the expected lease term. All leases are recorded with the exception of leases with an initial term of twelve months or less for which the Company made the short-term lease election. Within the Consolidated Statements of Condition, ROU assets are reported in other assets and the related lease liabilities are reported in other liabilities. In recognizing ROU assets and related lease liabilities, lease and non-lease components (such as taxes, insurance and common area maintenance costs) are accounted for separately as such amounts are generally readily determinable under the Company's lease contracts. Lease expense is recognized on a straight-line basis over the lease term and is recorded within occupancy and equipment expense in the Consolidated Statements of Income. Variable lease payments, which generally relate to the non-lease components noted above, are expensed as incurred. The following tables provide the components of lease cost and supplemental information: Years ended December 31 (in millions) 2021 2020 2019 Operating lease cost $ 63.0 $ 65.1 $ 61.6 Variable lease cost 9.8 10.0 8.6 Finance lease cost 0.3 0.3 0.1 Sublease income (2.2) (1.9) (1.4) Net lease cost $ 70.9 $ 73.5 $ 68.9 As of December 31 (dollars in millions) 2021 2020 Lease ROU assets: Operating lease $ 210.6 $ 234.9 Finance lease 2.1 2.3 Lease liabilities: Operating lease 242.0 270.4 Finance lease 4.5 4.9 Weighted-average discount rate: Operating leases 2.86 % 3.08 % Finance leases 2.59 2.59 Weighted-average remaining lease term (in years): Operating leases 7.2 7.6 Finance leases 10.3 11.2 Years ended December 31 (dollars in millions) 2021 2020 2019 Cash payments included in the measurement of lease liabilities: Reported in operating cash from operating leases $ 68.6 $ 66.6 $ 61.7 Reported in financing cash from finance leases 0.1 0.1 0.1 ROU assets obtained in exchange for lessee: Operating lease liabilities 31.4 22.8 89.1 Finance lease liabilities — — 2.6 The contractual maturities of the Company's lease liabilities as of December 31, 2021 were as follows: (in millions) Operating Leases Finance Leases 2022 $ 55.6 $ 0.5 2023 44.2 0.5 2024 38.8 0.5 2025 34.7 0.5 2026 24.5 0.5 Later years 74.1 2.6 Total lease payments 271.9 5.1 Less: Interest (29.9) (0.6) Total lease liabilities $ 242.0 $ 4.5 In the third quarter of 2021, the Company completed two sale-leaseback transactions on properties located in
Leases	NOTE 7 – Leases Lessor Arrangements People's United provides equipment financing to its customers through a variety of lessor arrangements, some of which may include options to renew and/or for the lessee to purchase the leased equipment at the end of the lease term. Direct financing leases and sales-type leases (collectively, “lease financing receivables”) are carried at the aggregate of lease payments receivable plus the estimated residual value of the leased assets and any initial direct costs incurred to originate these leases , less unearned income, which is accreted to interest income over the lease term using the interest method. The residual value component of a lease financing receivable represents the estimated fair value of the leased equipment at the end of the lease term. In establishing residual value estimates, the Company may rely on industry data, historical experience, independent appraisals and, where appropriate, information regarding product life cycle, product upgrades and competing products. Upon expiration of a lease, residual assets are remarketed, resulting in an extension of the lease by the lessee, a lease to a new customer or purchase of the residual asset by the lessee or another party. Impairment of residual values arises if the expected fair value is less than the carrying amount. The Company assesses its net investment in lease financing receivables (including residual values) for impairment on a quarterly basis with any impairment losses recognized in accordance with the impairment guidance for financial instruments. As such, net investment in lease financing receivables may be reduced by an ACL with changes recognized as provision expense. The composition of the Company’s total net investment in lease financing receivables included within equipment financing loans in the Consolidated Statements of Condition was as follows: As of December 31 (in millions) 2021 2020 Lease payments receivable $ 1,368.3 $ 1,418.4 Estimated residual value of leased assets 130.1 132.7 Gross investment in lease financing receivables 1,498.4 1,551.1 Plus: Deferred origination costs 10.2 11.6 Less: Unearned income (140.4) (150.7) Total net investment in lease financing receivables $ 1,368.2 $ 1,412.0 The contractual maturities of the Company's lease financing receivables were as follows: (in millions) December 31, 2021 2022 $ 532.9 2023 402.6 2024 292.0 2025 172.3 2026 83.0 Later years 15.6 Total $ 1,498.4 Operating lease income, generated in connection with operating leases for which the Company acts as a lessor, is recognized on a straight-line basis over the lease term as a component of non-interest income in the Consolidated Statements of Income. Depreciation expense for assets under operating leases, which are included in other assets in the Consolidated Statements of Condition, is generally recorded on a straight-line basis over the lease term as a component of non-interest expense in the Consolidated Statements of Income. The following table summarizes People's United's total lease income for the years ended December 31, 2021, 2020 and 2019: Years ended December 31 (in millions) 2021 2020 2019 Lease financing receivables $ 66.3 $ 69.0 $ 66.7 Operating leases 44.7 49.7 50.8 Total lease income $ 111.0 $ 118.7 $ 117.5 Lessee Arrangements Substantially all of the Company’s lessee arrangements represent non-cancelable operating leases for real estate (primarily branch locations) and office equipment with terms extending through 2054. Under these arrangements, People's United records right-of-use (“ROU”) assets and corresponding lease liabilities at lease commencement. Lease liabilities are recognized based on the present value of the remaining lease payments and discounted using the Company’s incremental borrowing rate for borrowings of similar term. ROU assets initially equal the related lease liability, adjusted for any lease payments made prior to the lease commencement and any lease incentives. Portions of certain properties are subleased for terms extending through 2038. At lease commencement, the Company considers renewal or termination options in the determination of the term of the lease. If it is reasonably certain that a renewal or termination option will be exercised, the effects of such options are included in the determination of the expected lease term. All leases are recorded with the exception of leases with an initial term of twelve months or less for which the Company made the short-term lease election. Within the Consolidated Statements of Condition, ROU assets are reported in other assets and the related lease liabilities are reported in other liabilities. In recognizing ROU assets and related lease liabilities, lease and non-lease components (such as taxes, insurance and common area maintenance costs) are accounted for separately as such amounts are generally readily determinable under the Company's lease contracts. Lease expense is recognized on a straight-line basis over the lease term and is recorded within occupancy and equipment expense in the Consolidated Statements of Income. Variable lease payments, which generally relate to the non-lease components noted above, are expensed as incurred. The following tables provide the components of lease cost and supplemental information: Years ended December 31 (in millions) 2021 2020 2019 Operating lease cost $ 63.0 $ 65.1 $ 61.6 Variable lease cost 9.8 10.0 8.6 Finance lease cost 0.3 0.3 0.1 Sublease income (2.2) (1.9) (1.4) Net lease cost $ 70.9 $ 73.5 $ 68.9 As of December 31 (dollars in millions) 2021 2020 Lease ROU assets: Operating lease $ 210.6 $ 234.9 Finance lease 2.1 2.3 Lease liabilities: Operating lease 242.0 270.4 Finance lease 4.5 4.9 Weighted-average discount rate: Operating leases 2.86 % 3.08 % Finance leases 2.59 2.59 Weighted-average remaining lease term (in years): Operating leases 7.2 7.6 Finance leases 10.3 11.2 Years ended December 31 (dollars in millions) 2021 2020 2019 Cash payments included in the measurement of lease liabilities: Reported in operating cash from operating leases $ 68.6 $ 66.6 $ 61.7 Reported in financing cash from finance leases 0.1 0.1 0.1 ROU assets obtained in exchange for lessee: Operating lease liabilities 31.4 22.8 89.1 Finance lease liabilities — — 2.6 The contractual maturities of the Company's lease liabilities as of December 31, 2021 were as follows: (in millions) Operating Leases Finance Leases 2022 $ 55.6 $ 0.5 2023 44.2 0.5 2024 38.8 0.5 2025 34.7 0.5 2026 24.5 0.5 Later years 74.1 2.6 Total lease payments 271.9 5.1 Less: Interest (29.9) (0.6) Total lease liabilities $ 242.0 $ 4.5 In the third quarter of 2021, the Company completed two sale-leaseback transactions on properties located in

Goodwill and Other Acquisition-

Goodwill and Other Acquisition-Related Intangible Assets	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Acquisition-Related Intangible Assets	NOTE 8 – Goodwill and Other Acquisition-Related Intangible Assets Goodwill Changes in the carrying amount of People’s United’s goodwill are summarized as follows: Operating Segment (in millions) Commercial Retail Wealth Total Balance at December 31, 2019 $ 1,966.1 $ 1,010.9 $ 88.5 $ 3,065.5 Sale of PUIA (1) — — (31.7) (31.7) Goodwill impairment — (353.0) — (353.0) Balance at December 31, 2020 1,966.1 657.9 56.8 2,680.8 Balance at December 31, 2021 $ 1,966.1 $ 657.9 $ 56.8 $ 2,680.8 (1) See Note 2. Goodwill is evaluated for impairment as of the annual measurement date or more frequently if a triggering event indicates that it is more likely than not that an impairment loss has been incurred. People’s United performed a quantitative assessment of goodwill impairment as of October 1, 2020 (its annual measurement date). A quantitative assessment includes determining the estimated fair value of each reporting unit, utilizing a combination of the discounted cash flow method of the income approach and the guideline public company method of the market approach, and comparing that fair value to each reporting unit's carrying amount. The income approach included a consideration of internal forecasts, growth rates, discount rates and terminal values. The market approach was based on a comparison of certain financial metrics of People’s United’s reporting units to guideline public company peers to derive selected trading multiples and incorporation of control premiums used. The Based on the quantitative assessment performed as of October 1, 2020, People’s United recognized a non-cash goodwill impairment charge totaling $353.0 million (representing 12% of total goodwill) associated with the Retail Banking reporting unit, while the fair values of the Commercial Banking and Wealth Management reporting units continued to exceed the respective carrying values by 4% and 103%, respectively. The projected cash flows of the Retail Banking reporting unit declined from prior period valuations due to record-low mortgage rates and the Federal Reserve’s updated guidance in the third quarter of 2020 regarding inflation targeting and expectations for interest rates to remain low for an extended period of time. The lower yielding and longer duration nature of the Company’s residential mortgage portfolio and a decline in home equity portfolio balances in recent years adversely impacted the Retail Banking reporting unit. For purposes of its October 1, 2021 goodwill impairment assessment the Company elected to perform a qualitative assessment for all three reporting units. This assessment considered several developments since the date of its 2020 annual impairment assessment, including: (i) a significant increase in the Company’s stock price; (ii) the financial performance of the reporting units relative to both the Company’s 2021 operating budget and the 2021 projections included in the discounted cash flow analysis prepared in connection with the 2020 annual impairment assessment; and (iii) the implicit value of the Company as supported by the M&T purchase price. Recent acquisitions have been undertaken with the objective of expanding the Company’s business, both geographically and through product offerings, as well as realizing synergies and economies of scale by combining with the acquired entities. For these reasons, a market-based premium was paid for the acquired entities which, in turn, resulted in the recognition of goodwill, representing the excess of the respective purchase prices over the estimated fair value of the net assets acquired. All of People’s United’s tax deductible goodwill was created in transactions in which the Company purchased the assets of the target (as opposed to purchasing the issued and outstanding stock of the target). At December 31, 2021 and 2020, tax deductible goodwill totaled $103.4 million and $113.6 million, respectively. Other Acquisition-Related Intangible Assets The following is a summary of People’s United’s other acquisition-related intangible assets: 2021 2020 As of December 31 (in millions) Gross Accumulated Carrying Gross Accumulated Carrying Core deposit intangible $ 303.9 $ 230.9 $ 73.0 $ 303.9 $ 206.3 $ 97.6 Trade name intangible 123.9 85.5 38.4 123.9 79.6 44.3 Client relationships 24.4 10.5 13.9 24.4 8.4 16.0 Trust relationships 42.7 40.2 2.5 42.7 37.6 5.1 Insurance relationships 38.1 38.1 — 38.1 38.1 — Favorable lease agreements 2.9 2.9 — 2.9 0.9 2.0 Non-compete agreements 0.6 0.6 — 0.6 0.5 0.1 Total other acquisition-related $ 536.5 $ 408.7 $ 127.8 $ 536.5 $ 371.4 $ 165.1 Other acquisition-related intangible assets subject to amortization have an original weighted-average amortization period of 12 years. Amortization expense of other acquisition-related intangible assets totaled $37.0 million, $40.8 million and $32.5 million for the years ended December 31, 2021, 2020 and 2019, respectively. Scheduled amortization expense attributable to other acquisition-related intangible assets for each of the next five years is as follows: $30.9 million in 2022; $23.2 million in 2023; $19.5 million in 2024; $16.7 million in 2025; and $13.8 million in 2026.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Premises and Equipment	NOTE 9 – Premises and Equipment The components of premises and equipment are summarized below: As of December 31 (in millions) 2021 2020 Land $ 48.0 $ 51.1 Buildings 303.5 313.6 Leasehold improvements 166.5 169.6 Furniture and equipment 280.7 277.3 Total 798.7 811.6 Less: Accumulated depreciation and amortization 556.9 534.9 Total premises and equipment, net $ 241.8 $ 276.7 Depreciation and amortization expense included in occupancy and equipment expense in the Consolidated Statements of Income totaled $44.0 million, $43.4 million and $41.7 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Other Assets and Other Liabilit

Other Assets and Other Liabilities	12 Months Ended
	Dec. 31, 2021
Other Assets And Other Liabilities [Abstract]
Other Assets and Other Liabilities	NOTE 10 – Other Assets and Other Liabilities The components of other assets are as follows: As of December 31 (in millions) 2021 2020 Affordable housing investments (note 14) $ 588.3 $ 460.8 Fair value of derivative financial instruments (notes 21 and 23) 388.1 800.3 Funded status of defined benefit pension plans (note 19) 256.4 141.2 Lease ROU assets (note 7) 212.7 237.2 Accrued interest receivable (notes 4 and 5) 167.2 202.2 Leased equipment 118.3 163.7 Assets held in trust for supplemental retirement plans (note 19) 94.5 56.9 Net deferred tax asset (note 14) 63.5 45.8 Economic development investments 33.8 29.1 Other prepaid expenses 26.5 32.7 Current income tax receivable (note 14) 18.6 44.7 Investment in joint venture 14.4 14.7 Loan disbursements in process 7.1 68.0 Mortgage servicing rights 4.3 4.8 Repossessed assets 3.7 5.7 REO: Residential 1.4 3.2 Commercial — 3.6 Other 26.6 37.6 Total other assets $ 2,025.4 $ 2,352.2 The components of other liabilities are as follows: As of December 31 (in millions) 2021 2020 Future contingent commitments for affordable housing investments (note 14) $ 264.5 $ 182.4 Lease liabilities (note 7) 246.5 275.3 Fair value of derivative financial instruments (notes 21 and 23) 95.3 170.4 Accrued expenses payable 92.8 82.6 Accrued employee benefits 90.3 72.2 Liabilities for supplemental retirement plans (note 19) 86.8 89.5 Liability for unsettled purchases of securities 45.5 194.8 Reserve for uncertain tax positions (note 14) 32.4 33.4 ACL on off-balance-sheet credit exposures (note 6) 28.4 26.9 Other postretirement plans (note 19) 16.5 17.7 Accrued interest payable 11.0 12.1 Loan payments in process — 28.3 Other 24.7 8.5 Total other liabilities $ 1,034.7 $ 1,194.1

Deposits

Deposits	12 Months Ended
	Dec. 31, 2021
Financial Services Costs [Abstract]
Deposits	NOTE 11 – Deposits The following is an analysis of People’s United’s total deposits by product type: 2021 2020 As of December 31 (dollars in millions) Amount Weighted- Amount Weighted- Non-interest-bearing $ 17,941.1 — % $ 15,881.7 — % Savings 6,733.7 0.02 6,029.7 0.04 Interest-bearing checking and money market 25,383.8 0.12 24,567.5 0.17 Time deposits maturing: Within 3 months 1,444.2 0.57 1,850.6 1.10 After 3 but within 6 months 836.7 0.25 1,155.1 0.68 After 6 months but within 1 year 807.7 0.20 1,464.1 0.75 After 1 but within 2 years 447.6 0.73 950.8 1.02 After 2 but within 3 years 76.2 0.43 165.7 1.75 After 3 but within 4 years 50.6 0.67 18.1 0.99 After 4 but within 5 years 33.7 0.33 54.4 0.68 After 5 years (1) — — — 0.99 Total 3,696.7 0.43 5,658.8 0.92 Total deposits $ 53,755.3 0.09 % $ 52,137.7 0.19 % (1) Amount totaled less than $0.1 million at December 31, 2020 (none at December 31, 2021). Time deposits issued in amounts that exceed $250,000 totaled $771.8 million and $1.2 billion at December 31, 2021 and 2020, respectively. Overdrafts of non-interest-bearing deposit accounts totaling $2.8 million at both December 31, 2021 and 2020 have been classified as loans. Interest expense on deposits is summarized as follows: Years ended December 31 (in millions) 2021 2020 2019 Savings $ 2.0 $ 5.4 $ 13.4 Interest-bearing checking and money market 38.4 86.8 195.9 Time 28.3 95.0 147.6 Total $ 68.7 $ 187.2 $ 356.9

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Borrowings	NOTE 12 – Borrowings People’s United’s borrowings are summarized as follows: 2021 2020 As of December 31 (dollars in millions) Amount Weighted- Amount Weighted- Fixed-rate FHLB advances maturing: After 1 month but within 1 year $ 551.2 0.37 % $ 556.9 0.41 % After 1 but within 2 years 0.5 0.05 1.2 0.50 After 2 but within 3 years — — 0.5 0.05 After 3 but within 4 years 8.5 1.70 — — After 4 but within 5 years 0.7 0.57 8.6 1.70 After 5 years 1.7 0.92 2.5 0.83 Total FHLB advances 562.6 0.39 569.7 0.43 Customer repurchase agreements maturing: Within 1 month 395.2 0.10 452.9 0.14 Total customer repurchase agreements 395.2 0.10 452.9 0.14 Federal funds purchased maturing: Within 1 month — — 125.0 0.07 Total federal funds purchased — — 125.0 0.07 Total borrowings $ 957.8 0.27 % $ 1,147.6 0.28 % At December 31, 2021, the Bank’s total borrowing capacity from (i) the FRB-NY and the FHLB of Boston for advances and (ii) repurchase agreements was $11.8 billion based on the level of qualifying collateral available for these borrowings. In addition, the Bank had unsecured borrowing capacity of $1.0 billion at that date. FHLB advances are secured by the Bank’s investment in FHLB stock and by a security agreement that requires the Bank to maintain, as collateral, sufficient qualifying assets not otherwise pledged (principally single-family residential mortgage loans, home equity lines of credit and loans, and commercial real estate loans). Interest expense on borrowings consists of the following: Years ended December 31 (in millions) 2021 2020 2019 FHLB advances $ 4.3 $ 13.7 $ 50.1 Customer repurchase agreements 0.4 1.1 2.2 Federal funds purchased — 5.4 24.6 Other borrowings — — 0.1 Total $ 4.7 $ 20.2 $ 77.0 Information concerning People’s United’s borrowings is presented below: As of and for the years ended December 31 (dollars in millions) 2021 2020 2019 FHLB advances: Balance at year end $ 562.6 $ 569.7 $ 3,125.4 Average outstanding during the year 569.6 1,371.2 2,098.0 Maximum outstanding at any month end 569.7 4,489.7 3,125.5 Average interest rate during the year 0.75 % 1.00 % 2.39 % Customer repurchase agreements: Balance at year end $ 395.2 $ 452.9 $ 409.1 Carrying amount of collateral securities at year end 403.1 462.0 418.0 Average outstanding during the year 394.3 379.0 296.6 Maximum outstanding at any month end 436.2 452.9 409.1 Average interest rate during the year 0.11 % 0.29 % 0.75 % Federal funds purchased: Balance at year end $ — $ 125.0 $ 1,620.0 Average outstanding during the year 52.8 688.2 1,127.5 Maximum outstanding at any month end 150.0 1,692.0 1,665.0 Average interest rate during the year 0.09 % 0.79 % 2.18 % Other borrowings: Balance at year end $ — $ — $ — Average outstanding during the year — — 3.3 Maximum outstanding at any month end — — 10.4 Average interest rate during the year — % — % 1.87 %

Notes and Debentures

Notes and Debentures	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Notes and Debentures	NOTE 13 – Notes and Debentures Notes and debentures are summarized as follows: As of December 31 (in millions) 2021 2020 People’s United Financial, Inc.: 3.65% senior notes due 2022 $ 499.6 $ 498.9 5.75% subordinated notes due 2024 78.8 80.2 People’s United Bank: 4.00% subordinated notes due 2024 414.4 430.5 Total notes and debentures $ 992.8 $ 1,009.6 The 3.65% senior notes represent fixed-rate unsecured and unsubordinated obligations of People’s United with interest payable semi-annually. The Company may redeem the senior notes at its option, in whole or in part, at any time prior to September 6, 2022, at a redemption price equal to the greater of (i) 100% of the principal amount of the senior notes to be redeemed or (ii) a “make-whole” amount, plus in either case accrued and unpaid interest to the redemption date. In addition, the Company may redeem the senior notes at its option, in whole or in part, at any time on or following September 6, 2022, at a redemption price equal to 100% of the principal amount of the senior notes to be redeemed, plus accrued and unpaid interest to the redemption date. People's United assumed the 5.75% subordinated notes in connection with its acquisition of United Financial. These subordinated notes, which were issued in September 2014, represent fixed-rate unsecured and unsubordinated obligations of People’s United with interest payable semi-annually. People's United may not redeem the subordinated notes prior to maturity without the prior approval of the FRB.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 14 – Income Taxes The following is a summary of total income tax expense: Years ended December 31 (in millions) 2021 2020 2019 Income tax expense applicable to pre-tax income $ 152.3 $ 129.0 $ 132.0 Deferred income tax (benefit) expense applicable to items reported in (16.5) 24.1 27.2 Total $ 135.8 $ 153.1 $ 159.2 The components of income tax expense applicable to pre-tax income are summarized as follows: Years ended December 31 (in millions) 2021 2020 2019 Current tax expense: Federal $ 116.0 $ 113.4 $ 90.8 State 33.7 34.3 26.9 Total current tax expense 149.7 147.7 117.7 Deferred tax expense (benefit) (1) 2.6 (18.7) 14.3 Total income tax expense $ 152.3 $ 129.0 $ 132.0 (1) Includes the effect of decreases in the valuation allowance for state deferred tax assets of $6.2 million, $13.7 million and $7.7 million in 2021, 2020 and 2019, respectively. The following is a reconciliation of expected income tax expense, computed at the U.S. federal statutory rate of 21% to actual income tax expense: 2021 2020 2019 Years ended December 31 (dollars in millions) Amount Rate Amount Rate Amount Rate Expected income tax expense $ 159.0 21.0 % $ 73.2 21.0 % $ 137.0 21.0 % State income tax, net of federal tax effect 27.1 3.6 23.9 6.8 22.6 3.4 Non-deductible FDIC insurance premiums 4.8 0.6 5.8 1.6 4.4 0.7 Tax-exempt interest (22.7) (3.0) (22.0) (6.3) (21.4) (3.3) Federal income tax credits (14.8) (1.9) (14.8) (4.2) (12.7) (2.0) Tax-exempt income from BOLI (2.4) (0.3) (2.7) (0.8) (2.2) (0.3) Tax benefits recognized in connection with: Equity-based compensation (0.5) (0.1) 1.3 0.4 (0.1) — Release of CT valuation allowance — — (7.1) (2.1) — — Non-deductible goodwill impairment (1) — — 74.1 21.3 — — Other, net 1.8 0.2 (2.7) (0.7) 4.4 0.7 Actual income tax expense $ 152.3 $ 129.0 $ 132.0 Effective income tax rate 20.1 % 37.0 % 20.2 % (1) See Note 8. Affordable Housing Investments People's United holds ownership interests in limited partnerships formed to develop and operate affordable housing units for lower income tenants throughout its franchise area. The underlying partnerships, which are considered variable interest entities, are not consolidated into the Company's Consolidated Financial Statements. These investments have historically played a role in enabling the Bank to meet its Community Reinvestment Act requirements while, at the same time, providing federal income tax credits. Affordable housing investments, including all legally binding commitments to fund future investments, are included in other assets in the Consolidated Statements of Condition ($588.3 million and $460.8 million at December 31, 2021 and 2020, respectively). Included in other liabilities in the Consolidated Statements of Condition is a liability for all legally binding unfunded commitments to fund future investments ($264.5 million and $182.4 million at those dates). The cost of the Company's investments is amortized on a straight-line basis over the period during which the related federal income tax credits are realized (generally ten years). Amortization expense, which is included as a component of income tax expense in the Consolidated Statements of Income, totaled $38.9 million, $31.4 million and $25.0 million for the years ended D.C. Solar Tax-Advantaged Investments As a result of its acquisition of United Financial, People’s United became a limited liability member in three In December 2018, Solutions and Distribution (collectively, “D.C. Solar”) had certain assets seized by the At the time of the Company’s acquisition of United Financial, further developments had occurred which served to increase the level of uncertainty with respect to the existence, condition and fair value of the generators. These factors were considered by the Company and, as a result, it was concluded that there was sufficient evidence to support that a full loss was probable. Accordingly, in connection with the related purchase accounting for United Financial, People’s United recorded a full write-down of the balance of the remaining investments in the LLCs of $8.4 million (after-tax) and established a reserve against tax benefits and credits of $18.9 million to reflect a full loss on the generators and the associated tax benefits previously realized by United Financial. In January 2020, the principals of D.C. Solar plead guilty in federal court to conspiracy to commit wire fraud and money laundering in connection with their role in a Ponzi scheme in which they: (i) sold solar generators that did not exist; (ii) made it appear as though solar generators existed in locations where they did not; (iii) created false financial statements; and Connecticut Passive Investment Company In 1998, the Bank formed a passive investment company, People's Mortgage Investment Company (“PMIC”), in accordance with Connecticut tax laws, which permit transfers of mortgage loans to such subsidiaries on or after As a result of continued business expansion and growth, including, in recent years, within the state of Connecticut, during 2020 the Bank completed a review of its state net deferred tax assets, including an assessment of the valuation allowance established for net operating loss carryforwards not expected to be utilized. Consequently, the Bank adjusted the estimated realizability of its state net deferred tax assets by $7.1 million and recorded this amount as a one-time decrease to the provision for income tax expense in the fourth quarter of 2020. The tax effects of temporary differences that give rise to People’s United’s deferred tax assets and liabilities are as follows: As of December 31 (in millions) 2021 2020 Deferred tax assets: Allowance for credit losses and non-accrual interest $ 96.2 $ 117.3 State tax net operating loss carryforwards, net of federal tax effect 59.6 65.9 Tax credits and net operating loss carryforwards 24.7 24.7 Equity-based compensation 20.3 19.9 Acquisition-related deferred tax assets 12.8 12.7 ROU lease assets, net of lease liabilities 7.6 8.6 D.C. Solar investment basis difference 6.8 6.8 Unrealized loss on debt securities available-for-sale 6.3 — Unrealized loss on debt securities transferred to held-to-maturity 1.4 2.5 Other deductible temporary differences 33.3 26.6 Total deferred tax assets 269.0 285.0 Less: valuation allowance for state deferred tax assets (52.5) (58.7) Total deferred tax assets, net of the valuation allowance 216.5 226.3 Deferred tax liabilities: Leasing activities (69.3) (88.3) Pension and other postretirement benefits (57.3) (25.6) Book over tax income recognized on consumer loans (17.2) (17.2) Mark-to-market and original issue discounts for tax purposes (3.7) (1.8) Temporary differences related to merchant services joint venture (3.3) (3.5) Unrealized gain on debt securities available-for-sale — (31.4) Other taxable temporary differences (2.2) (12.7) Total deferred tax liabilities (153.0) (180.5) Net deferred tax asset $ 63.5 $ 45.8 Based on People's United’s recent historical and anticipated future pre-tax earnings and the reversal of taxable temporary differences, management believes it is more likely than not that People's United will realize its total deferred tax assets, net of the valuation allowance. People's United’s current income tax receivable at December 31, 2021 and 2020 totaled $18.6 million and $44.7 million, respectively. The following is a reconciliation of the beginning and ending balances of People's United’s unrecognized income tax benefits related to uncertain tax positions: Years ended December 31 (in millions) 2021 2020 2019 Balance at beginning of year $ 33.4 $ 33.3 $ 5.2 Additions for tax positions taken in prior years — 0.1 0.5 Additions related to D.C. Solar: Established by United Financial prior to acquisition — — 8.7 Established by People's United subsequent to acquisition — — 18.9 Reductions attributable to audit settlements/lapse of statute of limitations (1) (1.0) — — Balance at end of year $ 32.4 $ 33.4 $ 33.3 (1) Reflects the resolution of a state tax apportionment matter arising as a result of a change in state tax legislation. If recognized, the unrecognized income tax benefits at December 31, 2021 would minimally affect People’s United’s annualized income tax rate. Accrued interest expense related to the unrecognized income tax benefits totaled $0.1 million at both December 31, 2021 and 2020. People’s United recognizes accrued interest related to unrecognized income tax benefits and penalties, if incurred, as components of income tax expense in the Consolidated Statements of Income. The amount of total unrecognized income tax benefits, excluding those related to D.C. Solar, is not expected to change significantly within the next twelve months. With respect to unrecognized income tax benefits related to D.C. Solar, timing remains uncertain given the nature of the matter, including the ongoing federal criminal investigation. People's United files a consolidated U.S. federal income tax return and various state income tax returns and is no longer subject to federal or state income tax examinations through 2016.

Stockholders' Equity and Divide

Stockholders' Equity and Dividends	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders' Equity and Dividends	NOTE 15 – Stockholders’ Equity and Dividends People’s United is authorized to issue (i) 50.0 million shares of preferred stock, par value of $0.01 per share, of which 10.0 million shares were issued at December 31, 2021, and (ii) 1.95 billion shares of common stock, par value of Treasury stock includes (i) common stock repurchased by People’s United, either directly or through agents, in the open market at prices and terms satisfactory to management in connection with stock repurchases authorized by its Board of Directors (106.4 million shares at December 31, 2021) and (ii) common stock purchased in the open market by a trustee with funds provided by People’s United and originally intended for awards under the People’s United Financial, Inc. 2007 Recognition and Retention Plan (the “RRP”) (2.6 million shares at December 31, 2021). Following shareholder approval of the People’s United Financial, Inc. 2014 Long-Term Incentive Plan (the “2014 Plan”) in 2014, no new awards may be granted under the RRP (see Note 20). In June 2019, the Company’s Board of Directors authorized the repurchase of up to 20.0 million shares of People’s United’s outstanding common stock. Such shares may be repurchased, either directly or through agents, in the open market at prices and terms satisfactory to management. During 2019, the Company repurchased 0.2 million shares of People's United common stock under this authorization at a total cost of $2.5 million. In the first quarter of 2020, the Company completed the repurchase authorization by purchasing 19.8 million shares of People's United common stock at a total cost of $304.4 million. In April 2007, People’s United established an ESOP (see Note 19). At that time, People’s United loaned the ESOP Common dividends declared and paid per common share totaled $0.7275, $0.7175 and $0.7075 for the years ended December 31, 2021, 2020 and 2019, respectively. People’s United’s common dividend payout ratio (common dividends paid as a percentage of net income available to common shareholders) was 52.1%, 148.0% and 54.3% for the years ended In the ordinary course of business, People’s United (parent company) is dependent upon dividends from the Bank to provide funds for the payment of dividends to its shareholders and other general corporate purposes. People’s United’s ability to pay cash dividends is governed by federal law, regulations and related guidance. The Bank’s ability to pay cash dividends directly or indirectly to People’s United also is governed by federal law and regulations. These provide that the Bank must receive OCC approval to declare a dividend if the total amount of all dividends (common and preferred), including the proposed dividend, declared by the Bank in any current year exceeds the total of the Bank’s net income for the current year to date, combined with its retained net income for the previous two years, less the sum of any transfers required by the OCC and any transfers required to be made to a fund for the retirement of any preferred stock. The term “retained net income” as defined by federal regulations means the Bank’s net income for a specified period less the total amount of all dividends declared in that period. The Bank may not pay dividends to People’s United if, after paying those dividends, it would fail to meet the required minimum levels under risk-based capital guidelines or if the OCC has notified the Bank that it is in need of more than normal supervision. See Note 16 for a discussion of regulatory capital requirements. Under the Federal Deposit Insurance Act, an insured depository institution such as the Bank is prohibited from making capital distributions, including the payment of dividends, if, after making such distribution, the institution would become “undercapitalized” (as such term is used in the Federal Deposit Insurance Act). Payment of dividends by the Bank also may be restricted at any time at the discretion of the appropriate regulator if it deems the payment to constitute an unsafe and unsound banking practice. In 2021, 2020 and 2019, the Bank paid a total of $437.0 million, $498.0 million and $457.0 million, respectively, in cash dividends to People’s United (parent company). At December 31, 2021, the Bank’s retained net income, as defined by federal regulations, totaled $(60.8) million.

Regulatory Capital Requirements

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2021
Financial Services Costs [Abstract]
Regulatory Capital Requirements	NOTE 16 – Regulatory Capital Requirements Bank holding companies and banks are subject to various regulations regarding capital requirements administered by Both People’s United and the Bank are subject to capital rules (the “Basel III capital rules”) issued by U.S. banking agencies. The Basel III capital rules require U.S. financial institutions to maintain: (i) a minimum ratio of Common Equity In order to avoid limitations on distributions, including dividend payments, and certain discretionary bonus payments, a financial institution must hold a capital conservation buffer of 2.50% above its minimum risk-based capital requirements. For regulatory capital purposes, subordinated note issuances qualify, up to certain limits, as Tier 2 capital for Total In December 2018, the Federal banking agencies approved a final rule allowing an option to phase-in, over three years, the day one regulatory capital effects of the CECL standard. In March 2020, the Federal banking agencies issued an interim final rule providing an alternative option to delay, for two years, an estimate of the CECL standard’s effect on regulatory capital (relative to incurred loss methodology's effect on regulatory capital), followed by a three-year transition period. The Company elected the alternative option provided in the March 2020 interim final rule. The foregoing capital ratios are based in part on specific quantitative measures of assets, liabilities and certain Management believes that, as of December 31, 2021, both People's United and the Bank met all capital adequacy requirements to which each is subject. Further, the most recent regulatory notification categorized the Bank as a The following is a summary of People's United’s and the Bank's regulatory capital amounts and ratios under the Basel III capital rules. The minimum capital required amounts are based on the capital conservation buffer of the Basel III capital rules. In connection with the adoption of the Basel III capital rules, both the Company and the Bank elected to opt-out of the requirement to include most components of AOCL in CET 1 capital. At December 31, 2021, People's United's and the Bank's total risk-weighted assets, as defined, were both $41.8 billion compared to $45.1 billion and $45.0 billion, respectively, at December 31, 2020. For regulatory capital purposes, PPP loans are assigned a zero risk-weighting as a result of the related SBA guarantee on such loans. As of December 31, 2021 Minimum Capital Classification as (dollars in millions) Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Capital (1): People’s United $ 5,326.7 8.5 % $ 2,502.0 4.0 % N/A N/A Bank 5,403.6 8.6 2,501.8 4.0 $ 3,127.2 5.0 % CET 1 Risk-Based Capital (2): People’s United 5,082.6 12.2 2,925.6 7.0 N/A N/A Bank 5,403.6 12.9 2,925.0 7.0 2,716.0 6.5 Tier 1 Risk-Based Capital (3): People’s United 5,326.7 12.7 3,552.5 8.5 2,507.6 6.0 Bank 5,403.6 12.9 3,551.7 8.5 3,342.8 8.0 Total Risk-Based Capital (4): People’s United 5,793.3 13.9 4,388.3 10.5 4,179.4 10.0 Bank 5,840.2 14.0 4,387.4 10.5 4,178.5 10.0 As of December 31, 2020 Minimum Capital Classification as (dollars in millions) Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Capital (1): People’s United $ 4,967.8 8.3 % $ 2,388.4 4.0 % N/A N/A Bank 5,168.4 8.7 2,387.9 4.0 $ 2,984.8 5.0 % CET 1 Risk-Based Capital (2): People’s United 4,723.7 10.5 3,155.3 7.0 N/A N/A Bank 5,168.4 11.5 3,151.1 7.0 2,926.0 6.5 Tier 1 Risk-Based Capital (3): People’s United 4,967.8 11.0 3,831.4 8.5 2,704.5 6.0 Bank 5,168.4 11.5 3,826.3 8.5 3,601.3 8.0 Total Risk-Based Capital (4): People’s United 5,589.5 12.4 4,732.9 10.5 4,507.5 10.0 Bank 5,745.1 12.8 4,726.7 10.5 4,501.6 10.0 (1) Tier 1 Leverage Capital ratio represents CET 1 Capital plus Additional Tier 1 Capital instruments (together, (2) CET 1 Risk-Based Capital ratio represents equity capital, as defined, less: (i) after-tax net unrealized gains (losses) on certain securities classified as available-for-sale; (ii) after-tax net unrealized gains (losses) on securities transferred to held-to-maturity; (iii) goodwill and other acquisition-related intangible assets; and (iv) the amount recorded in AOCL relating to pension and other postretirement benefits divided by Total Risk-Weighted Assets. (3) Tier 1 Risk-Based Capital ratio represents Tier 1 Capital divided by Total Risk-Weighted Assets. (4) Total Risk-Based Capital ratio represents Tier 1 Capital plus subordinated notes and debentures, up to certain limits, and the ACL, up to 1.25% of Total Risk-Weighted Assets, divided by Total Risk-Weighted Assets.

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Common Share	NOTE 17 – Earnings Per Common Share The following is an analysis of People’s United’s basic and diluted EPS, reflecting the application of the two-class method, as described in Note 1: Years ended December 31 (in millions, except per common share data) 2021 2020 2019 Net income available to common shareholders $ 590.8 $ 205.5 $ 506.3 Dividends paid on and undistributed earnings allocated — — (0.2) Earnings attributable to common shareholders $ 590.8 $ 205.5 $ 506.1 Weighted average common shares outstanding for basic EPS 420.8 420.3 394.0 Effect of dilutive equity-based awards 3.7 2.3 3.2 Weighted average common shares and common-equivalent 424.5 422.6 397.2 EPS: Basic $ 1.40 $ 0.49 $ 1.28 Diluted 1.39 0.49 1.27 All unallocated ESOP common shares and all common shares accounted for as treasury shares have been excluded from the calculation of basic and diluted EPS. Anti-dilutive equity-based awards totaling 11.3 million shares, 18.0 million shares and 6.7 million shares for the years ended December 31, 2021, 2020 and 2019, respectively, have also been excluded from the calculation of diluted EPS.

Comprehensive Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Comprehensive Income	NOTE 18 – Comprehensive Income Comprehensive income represents the sum of net income and items of “other comprehensive income or loss,” including (on an after-tax basis): (i) net actuarial gains and losses, prior service credits and costs, and transition assets and obligations related to People’s United’s pension and other postretirement plans; (ii) net unrealized gains and losses on debt securities available-for-sale; (iii) net unrealized gains and losses on debt securities transferred to held-to-maturity; and (iv) net unrealized gains and losses on derivatives accounted for as cash flow hedges. People’s United’s total comprehensive income for the years ended December 31, 2021, 2020 and 2019 is reported in the Consolidated Statements of Comprehensive Income. The following is a summary of the changes in the components of AOCL, which are included in People’s United’s stockholders’ equity on an after-tax basis: (in millions) Pension Net Unrealized Net Unrealized Net Unrealized Total Balance at December 31, 2018 $ (192.5) $ (47.0) $ (15.3) $ (2.0) $ (256.8) Other comprehensive income (loss) 9.7 67.9 — 1.5 79.1 Amounts reclassified from AOCL (1) 6.6 (0.1) 3.5 0.8 10.8 Current period other comprehensive 16.3 67.8 3.5 2.3 89.9 Balance at December 31, 2019 (176.2) 20.8 (11.8) 0.3 (166.9) Other comprehensive income (loss) (12.0) 82.3 — (1.0) 69.3 Amounts reclassified from AOCL (1) 6.4 — 3.6 (1.6) 8.4 Current period other comprehensive (5.6) 82.3 3.6 (2.6) 77.7 Balance at December 31, 2020 (181.8) 103.1 (8.2) (2.3) (89.2) Other comprehensive income (loss) 61.7 (122.4) — 0.9 (59.8) Amounts reclassified from AOCL (1) 7.0 — 3.8 1.4 12.2 Current period other comprehensive 68.7 (122.4) 3.8 2.3 (47.6) Balance at December 31, 2021 $ (113.1) $ (19.3) $ (4.4) $ — $ (136.8) (1) See the following table for details about these reclassifications. The following is a summary of the amounts reclassified from AOCL: Years ended December 31 (in millions) Amounts Reclassified Affected Line Item 2021 2020 2019 Details about components of AOCL: Amortization of pension and Net actuarial loss $ (9.0) $ (8.4) $ (8.3) (1) (9.0) (8.4) (8.3) Income before income tax expense 2.0 2.0 1.7 Income tax expense (7.0) (6.4) (6.6) Net income Reclassification adjustment for net — — 0.1 Income before income tax expense (2) — — — Income tax expense — — 0.1 Net income Amortization of unrealized losses on (4.9) (4.7) (4.6) Income before income tax expense (3) 1.1 1.1 1.1 Income tax expense (3.8) (3.6) (3.5) Net income Amortization of unrealized gains and Interest rate swaps (1.9) 1.9 (1.2) (4) Interest rate locks 0.1 0.1 0.1 (4) (1.8) 2.0 (1.1) Income before income tax expense 0.4 (0.4) 0.3 Income tax expense (1.4) 1.6 (0.8) Net income Total reclassifications for the period $ (12.2) $ (8.4) $ (10.8) (1) Included in the computation of net periodic benefit income (expense) reflected in other non-interest expense (see Note 19 for additional details). (2) Included in non-interest income. (3) Included in interest and dividend income — securities. (4) Included in interest expense — notes and debentures. Deferred income taxes applicable to the components of AOCL are as follows: As of December 31 (in millions) 2021 2020 2019 Net actuarial loss and other amounts related to pension and $ 36.9 $ 57.0 $ 55.3 Net unrealized loss (gain) on debt securities available-for-sale 6.3 (32.1) (6.6) Net unrealized loss on debt securities transferred to held-to-maturity 1.4 2.5 3.6 Net unrealized loss (gain) on derivatives accounted for as cash flow hedges — 0.7 (0.1) Total deferred income taxes $ 44.6 $ 28.1 $ 52.2 The following is a summary of the components of People’s United’s total other comprehensive income (loss): Year ended December 31, 2021 (in millions) Pre-Tax Tax Effect After-Tax Net actuarial gains and losses on pension and other postretirement plans: Net actuarial gain arising during the year $ 79.8 $ (18.1) $ 61.7 Reclassification adjustment for net actuarial loss included in net income 9.0 (2.0) 7.0 Net actuarial gain 88.8 (20.1) 68.7 Net unrealized gains and losses on debt securities available-for-sale: Net unrealized holding losses arising during the year (160.8) 38.4 (122.4) Net unrealized losses (160.8) 38.4 (122.4) Net unrealized gains and losses on debt securities transferred to held-to-maturity: Reclassification adjustment for amortization of unrealized losses on debt 4.9 (1.1) 3.8 Net unrealized gains 4.9 (1.1) 3.8 Net unrealized gains and losses on derivatives accounted for as cash flow hedges: Net unrealized gains arising during the year 1.2 (0.3) 0.9 Reclassification adjustment for net realized losses included in net income 1.8 (0.4) 1.4 Net unrealized gains 3.0 (0.7) 2.3 Total other comprehensive loss $ (64.1) $ 16.5 $ (47.6) Year ended December 31, 2020 (in millions) Pre-Tax Tax Effect After-Tax Net actuarial gains and losses on pension and other postretirement plans: Net actuarial loss arising during the year $ (15.7) $ 3.7 $ (12.0) Reclassification adjustment for net actuarial loss included in net income 8.4 (2.0) 6.4 Net actuarial loss (7.3) 1.7 (5.6) Net unrealized gains and losses on debt securities available-for-sale: Net unrealized holding gains arising during the year 107.8 (25.5) 82.3 Net unrealized gains 107.8 (25.5) 82.3 Net unrealized gains and losses on debt securities transferred to held-to-maturity: Reclassification adjustment for amortization of unrealized losses on debt 4.7 (1.1) 3.6 Net unrealized gains 4.7 (1.1) 3.6 Net unrealized gains and losses on derivatives accounted for as cash flow hedges: Net unrealized losses arising during the year (1.4) 0.4 (1.0) Reclassification adjustment for net realized gains included in net income (2.0) 0.4 (1.6) Net unrealized losses (3.4) 0.8 (2.6) Total other comprehensive income $ 101.8 $ (24.1) $ 77.7 Year ended December 31, 2019 (in millions) Pre-Tax Tax Effect After-Tax Net actuarial gains and losses on pension and other postretirement plans: Net actuarial gain arising during the year $ 12.1 $ (2.4) $ 9.7 Reclassification adjustment for net actuarial loss included in net income 8.3 (1.7) 6.6 Net actuarial gain 20.4 (4.1) 16.3 Net unrealized gains and losses on debt securities available-for-sale: Net unrealized holding gains arising during the year 89.2 (21.3) 67.9 Reclassification adjustment for net realized losses included in net income (0.1) — (0.1) Net unrealized gains 89.1 (21.3) 67.8 Net unrealized gains and losses on debt securities transferred to held-to-maturity: Reclassification adjustment for amortization of unrealized losses on debt 4.6 (1.1) 3.5 Net unrealized gains 4.6 (1.1) 3.5 Net unrealized gains and losses on derivatives accounted for as cash flow hedges: Net unrealized gains arising during the year 1.9 (0.4) 1.5 Reclassification adjustment for net realized losses included in net income 1.1 (0.3) 0.8 Net unrealized gains 3.0 (0.7) 2.3 Total other comprehensive income $ 117.1 $ (27.2) $ 89.9

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Employee Benefit Plans	NOTE 19 – Employee Benefit Plans People’s United Employee Pension and Other Postretirement Plans People’s United maintains a qualified noncontributory defined benefit pension plan (the “People’s Qualified Plan”) that covers substantially all full-time and part-time employees who (i) meet certain age and length of service requirements and (ii) were employed by the Bank prior to August 14, 2006. Benefits are based upon the employee’s years of credited service and either the average compensation for the last five years or the average compensation for the five New employees of the Bank starting on or after August 14, 2006 are not eligible to participate in the People’s Qualified Plan. Instead, the Bank makes contributions on behalf of these employees to a qualified defined contribution plan in an annual amount equal to 3% of the employee’s eligible compensation. Employee participation in this plan is restricted to employees who (i) are at least 18 years of age and (ii) worked at least 1000 hours in a year. Both full-time and part-time employees are eligible to participate as long as they meet these requirements. In July 2011, the Bank amended the People’s Qualified Plan to “freeze”, effective December 31, 2011, the accrual of pension benefits for People’s Qualified Plan participants. As such, participants will not earn any additional benefits after that date. Instead, effective January 1, 2012, the Bank began making contributions on behalf of these participants to a qualified defined contribution plan in an annual amount equal to 3% of the employee’s eligible compensation. In addition to the People’s Qualified Plan, People’s United maintained the qualified defined benefit pension plan that covered former United Financial employees who met certain eligibility requirements (the “United Financial Qualified Plan”). All benefits under this plan were frozen effective December 31, 2012. Effective March 31, 2021, the United Financial Qualified Plan was merged into the People’s Qualified Plan (together the “Qualified Plan”). People’s United also maintains (i) unfunded, nonqualified supplemental plans to provide retirement benefits to certain senior officers (the “People’s Supplemental Plans”) and (ii) an unfunded plan that provides retirees with optional medical, dental and life insurance benefits (the “People’s Postretirement Plan”). People’s United accrues the cost of these postretirement benefits over the employees’ years of service to the date of their eligibility for such benefit. People’s United also continues to maintain: (1) for certain eligible former First Connecticut Bancorp, Inc. (“First Connecticut”) employees (i) an unfunded, nonqualified supplemental retirement plan (the “First Connecticut Supplemental Plan”) and (ii) unfunded plans that provide medical, dental and life insurance benefits (the “First Connecticut Postretirement Plans”); (2) for certain eligible former BSB Bancorp employees (i) an unfunded, nonqualified supplemental retirement plan (the “BSB Bancorp Supplemental Plan”) and (ii) unfunded plans that provide life insurance benefits (the “BSB Bancorp Post Retirement Welfare (Life Insurance) Plan”); and (3) for certain former United Financial employees (i) an unfunded, nonqualified supplemental retirement plan (the “United Financial Supplemental Plan”) and (ii) unfunded plans that provide medical, dental and life insurance benefits (the “United Financial Postretirement Benefit Plan”). An employer is required to recognize an asset or a liability for the funded status of pension and other postretirement plans. The funded status is measured as the difference between the fair value of plan assets and the applicable benefit obligation, which is the projected benefit obligation for a pension plan and the accumulated postretirement benefit obligation for another postretirement plan. Plan assets and benefit obligations are required to be measured as of the date of the employer’s fiscal year-end. The following table summarizes changes in the benefit obligations and plan assets of (i) the Qualified Plan, the People's Supplemental Plans, the First Connecticut Supplemental Plan, the BSB Bancorp Supplemental Plan and the United Financial Supplemental Plan (together the “Pension Plans”) and (ii) the People’s Postretirement Plan, the First Connecticut Postretirement Plans, the BSB Bancorp Post Retirement Welfare (Life Insurance) Plan and the United Financial Postretirement Benefit Plan (together the “Other Postretirement Plans”). The table also shows the funded status (or the difference between benefit obligations and plan assets) recognized in the Consolidated Statements of Condition. All plans have a December 31 measurement date. Pension Plans Other (in millions) 2021 2020 2021 2020 Benefit obligations: (1) Beginning of year $ 740.5 $ 665.5 $ 17.7 $ 18.7 Service cost — — 0.3 0.3 Interest cost 16.2 19.7 0.4 0.6 Actuarial loss (gain) (24.8) 85.9 (1.3) (1.5) Benefits paid (29.6) (30.0) (0.6) (0.4) Settlements (2.7) (0.6) — — End of year 699.6 740.5 16.5 17.7 Fair value of plan assets: Beginning of year 839.9 746.7 — — Actual return on assets 107.7 120.2 — — Employer contributions 5.4 3.6 0.6 0.4 Benefits paid (29.6) (30.0) (0.6) (0.4) Settlements (2.7) (0.6) — — End of year 920.7 839.9 — — Funded status at end of year $ 221.1 $ 99.4 $ (16.5) $ (17.7) Amounts recognized in the Consolidated Statements Other assets $ 256.4 $ 141.2 $ — $ — Other liabilities (35.3) (41.8) (16.5) (17.7) Funded status at end of year $ 221.1 $ 99.4 $ (16.5) $ (17.7) (1) Represents the projected benefit obligation for the Pension Plans and the accumulated benefit obligation for the Other Postretirement Plans. Although the People’s Supplemental Plans and the First Connecticut Supplemental Plan (together the “Supplemental Plans”) hold no assets, People’s United has funded trusts to provide benefit payments to the extent such benefits are not paid directly by People’s United. Trust assets of $40.5 million as of December 31, 2021 (which are included in other assets in the Consolidated Statements of Condition) exceeded the related projected benefit obligation of $35.3 million at that date. The following table summarizes the accumulated and projected benefit obligations for the Pension Plans at the respective measurement dates: Pension Plans As of December 31 (in millions) 2021 2020 Accumulated benefit obligations: Qualified Plan $ 664.3 $ 698.7 Supplemental Plans 35.0 41.6 Total $ 699.3 $ 740.3 Projected benefit obligations: Qualified Plan $ 664.3 $ 698.7 Supplemental Plans 35.3 41.8 Total $ 699.6 $ 740.5 Components of net periodic benefit (income) expense and other amounts recognized in other comprehensive income (loss) are as follows: Pension Plans Other Years ended December 31 (in millions) 2021 2020 2019 2021 2020 2019 Net periodic benefit (income) expense: Interest cost $ 16.2 $ 19.7 $ 22.9 $ 0.7 $ 0.9 $ 0.9 Expected return on plan assets (54.2) (49.5) (46.1) — — — Recognized net actuarial loss 8.2 7.9 5.3 — 0.2 0.1 Settlements (1) 0.8 0.2 2.9 — — — Net periodic benefit (income) expense (29.0) (21.7) (15.0) 0.7 1.1 1.0 Other changes in plan assets and benefit obligations Net actuarial (gain) loss (87.3) 7.5 (20.5) (1.3) (1.6) 1.1 Total pre-tax changes recognized in other (87.3) 7.5 (20.5) (1.3) (1.6) 1.1 Total recognized in net periodic benefit $ (116.3) $ (14.2) $ (35.5) $ (0.6) $ (0.5) $ 2.1 (1) Settlement charges are a result of lump-sum benefit payments in excess of the sum of a plan’s annual interest and service costs. When an employer settles the full amount of its obligation for vested benefits with respect to some of a plan’s participants, the employer is required to recognize in income a pro-rata portion of the aggregate gain or loss recorded in AOCL. The pre-tax amounts in AOCL that have not been recognized as components of net periodic benefit (income) expense are as follows: Pension Plans Other As of December 31 (in millions) 2021 2020 2021 2020 Net actuarial loss $ 148.7 $ 236.0 $ 1.0 $ 2.3 Total pre-tax amounts included in AOCL $ 148.7 $ 236.0 $ 1.0 $ 2.3 The Company uses a corridor approach in the valuation of its Qualified Plan, which results in the deferral of actuarial gains and losses resulting from differences between actual results and actuarial assumptions. Amortization of actuarial gains and losses occurs when the accumulated unrecognized gain or loss balance, as of the beginning of the year, exceeds 10% of the greater of the projected benefit obligation or the market-related value of plan assets. The excess unrecognized gain or loss balance is amortized over the average remaining life expectancy of plan participants for the Qualified Plan (approximately The following assumptions were used in determining the benefit obligations and net periodic benefit (income) expense as of and for the periods indicated: Qualified Plans Other Postretirement Plans 2021 2020 2019 2021 2020 2019 Weighted-average assumptions used to determine Discount rate: People’s Qualified Plan 2.86 % 2.50 % 3.38 % 2.90 % 2.50 % 3.40 % First Connecticut Qualified Plan (1) n/a n/a 3.39 n/a n/a n/a United Financial Qualified Plan (2) n/a 2.53 3.42 n/a n/a n/a Rate of compensation increase n/a n/a n/a n/a n/a n/a Weighted-average assumptions used to determine net Discount rate: People’s Qualified Plan (3) 2.50%/3.14% 3.38 % 4.41 % 2.50 % 3.40 % 4.40 % First Connecticut Qualified Plan (1) n/a 3.39 4.41 n/a n/a n/a United Financial Qualified Plan (2) 2.53 3.42 3.33 n/a n/a n/a Expected return on plan assets: People’s Qualified Plan 7.25 7.25 7.25 n/a n/a n/a First Connecticut Qualified Plan (1) n/a n/a 6.00 n/a n/a n/a United Financial Qualified Plan (2) 5.25 5.25 5.25 n/a n/a n/a Rate of compensation increase n/a n/a n/a n/a n/a n/a Assumed health care cost trend rates at December 31: Health care cost trend rate assumed for next year n/a n/a n/a 5.20 % 5.50 % 5.70 % Rate to which the cost trend rate is assumed to n/a n/a n/a 4.50 4.50 4.50 Year that the rate reaches the ultimate trend rate n/a n/a n/a 2037 2037 2037 n/a — not applicable (1) Effective December 31, 2020, the First Connecticut Qualified Plan was merged into the People’s Qualified Plan. (2) Effective March 31, 2021, the United Financial Qualified Plan was merged into the People’s Qualified Plan. (3) Rate of 2.50% through March 31, 2021 and 3.14% through December 31, 2021. The discount rates used to determine the benefit obligation of the Supplemental Plans at December 31, 2021 ranged from 2.18% to 2.90%, while the discount rate used to determine net periodic benefit (income) expense for 2021 ranged from 1.84% to 2.90%. The discount rates used to determine the benefit obligation of the Supplemental Plans at December 31, 2020 ranged from 1.60% to 2.50%, while the discount rate used to determine net periodic benefit (income) expense for 2020 ranged from 1.29% to 2.50%. The discount rates reflect the then current rates available on long-term high-quality fixed-income debt instruments, and are reset annually on the measurement date. To determine the discount rates, People’s United reviews, along with its independent actuary, spot interest rate yield curves based upon yields from a broad population of high-quality bonds adjusted to match the timing and amounts of expected benefit payments. People’s United uses a full yield curve approach to estimate the interest cost component of net periodic benefit income by applying the specific spot rates along the yield curve, used in the determination of the benefit obligations, to the relevant projected cash flows. In developing an expected long-term rate of return on asset assumption for the qualified plans for purposes of determining 2021 net periodic benefit income, People’s United considered the historical returns and the future expectations for returns within each asset class, as well as the target asset allocation of the pension portfolio. This resulted in an expected In 2022, $35.6 million in net periodic benefit income is expected to be recognized related to the Qualified Plan. This amount was determined using the following assumptions: (i) expected long-term rate of return of 7.25%; (ii) discount rate of 2.86%; and (iii) updated mortality tables issued by the Society of Actuaries in the fourth quarter of 2021. The mortality rate is a key assumption used in valuing retirement benefit obligations as it reflects the probability of future benefit payments that are contingent upon the longevity of plan participants and their beneficiaries. People’s United’s funding policy is to contribute the amounts required by applicable regulations, although additional amounts may be contributed from time to time. Employer contributions for the Supplemental Plans and the Other Postretirement Plans in 2022 are expected to total $4.1 million, representing net benefit payments expected to be paid under these plans. Expected future net benefit payments for the Pension Plans as of December 31, 2021 are: $31.3 million in 2022; $32.9 million in 2023; $34.8 million in 2024; $35.0 million in 2025; $37.4 million in 2026; and an aggregate of $193.9 million in 2027 through 2031. As of December 31, 2021, expected future net benefit payments for the Other Postretirement Plans are The investment strategy of the Qualified Plan is to develop a diversified portfolio, representing a variety of asset classes of varying duration, in order to effectively fund expected near-term and long-term benefit payments. All investment decisions are governed by an established policy that contains the following asset allocation guidelines: Asset Class Policy Target % Policy Range % Cash equivalents 1 0-20 Equity securities 71 55-75 Fixed income securities 28 10-40 Equity investments are required to be diversified among industries and economic sectors and may be invested directly in individual securities or indirectly through the use of mutual funds, trust company common funds, REIT's, investment partnerships, LLCs or exchange traded funds. Limitations have been established on the overall allocation to any individual security representing more than 3% of the market value of plan assets. A limit of 50% of equity holdings may be invested in international equities. Short sales, margin purchases, physical commodities and future contracts, and exchange traded or Fixed income securities are oriented toward risk-averse, investment-grade securities rated “A” or higher. A limit of up to 30% of the fixed income holdings may be purchased and held indirectly in issues rated below “Baa3” by Moody’s or “BBB-” by Standard & Poor’s, if the higher investment risk is compensated for by the prospect of a positive incremental investment return. With the exception of U.S. government securities, in which the Qualified Plan may invest the entire fixed income allocation, fixed income securities require diversification among individual securities and sectors. Limitations have been established on the overall investment in securities of a single issuer to no more than 2.5% of the market value of total plan assets. There is no limit on the maximum maturity of securities held. The following table summarizes the percentages of fair value for the major categories of assets in the qualified plans as of the respective measurement dates: Plan Assets 2021 2020 As of December 31 People’s United Financial People’s United Financial Equity securities 70 % n/a 70 % 4 % Cash and fixed income securities 30 n/a 30 96 Total 100 % n/a 100 % 100 % (1) Effective March 31, 2021, the United Financial Qualified Plan was merged into the People’s Qualified Plan. (2) The United Financial Qualified Plan was not yet aligned with the Company's investment strategy and asset allocation guidelines as the acquisition of United Financial occurred effective November 1, 2019. The following tables present the Qualified Plan’s assets measured at fair value: Fair Value Measurements Using As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 41.5 $ — $ — $ 41.5 Equity securities: Common stocks 353.5 — — 353.5 Mutual funds — 287.1 — 287.1 Fixed income securities: Mutual funds — 118.1 — 118.1 Corporate — 75.8 — 75.8 U.S. Treasury — 43.9 — 43.9 Other — 0.8 — 0.8 Total $ 395.0 $ 525.7 $ — $ 920.7 Fair Value Measurements Using As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 23.9 $ — $ — $ 23.9 Equity securities: Common stocks 302.6 — — 302.6 Mutual funds — 259.6 — 259.6 Fixed income securities: Mutual funds — 103.3 — 103.3 Corporate — 96.5 — 96.5 U.S. Treasury — 52.5 — 52.5 Other — 1.5 — 1.5 Total $ 326.5 $ 513.4 $ — $ 839.9 Employee Stock Ownership Plan In April 2007, People’s United established an ESOP. At that time, People’s United loaned the ESOP $216.8 million to purchase 10,453,575 shares of People’s United common stock in the open market. In order for the ESOP to repay the loan, People’s United expects to make annual cash contributions of approximately $18.8 million until 2036. Such cash contributions may be reduced by the cash dividends paid on unallocated ESOP shares, which totaled $4.1 million in 2021, $4.3 million in 2020 and $4.4 million in 2019. At December 31, 2021, the loan balance totaled $161.2 million. Employee participation in this plan is restricted to those employees who (i) are at least 18 years of age and (ii) worked at least 1000 hours within 12 months of their hire date or any plan year (January 1 to December 31) after their date of hire. Employees meeting the aforementioned eligibility criteria during the plan year must continue to be employed as of the last day of the plan year in order to receive an allocation of shares for that plan year. Shares of People’s United common stock are held by the ESOP and allocated to eligible participants annually based upon a percentage of each participant’s eligible compensation. Since the ESOP was established, a total of 5,226,788 shares of People’s United common stock have been allocated or committed to be released to participants’ accounts. At Compensation expense related to the ESOP is recognized at an amount equal to the number of common shares committed to be released by the ESOP for allocation to participants’ accounts multiplied by the average fair value of People’s United’s common stock during the reporting period. The difference between the fair value of the shares of People’s United’s common stock committed to be released and the cost of those common shares is recorded as a credit to additional paid-in capital (if fair value exceeds cost) or, to the extent that no such credits remain in additional paid-in capital, as a charge to retained earnings (if fair value is less than cost). Expense recognized for the ESOP totaled $5.9 million, $4.3 million and $5.7 million for the years ended December 31, 2021, 2020 and 2019, respectively. Employee Savings Plans People’s United sponsors an employee savings plan that qualifies as a 401(k) plan under the Internal Revenue Code. Employees may contribute up to 50% of their pre-tax compensation up to certain limits, and People’s United makes a matching contribution equal to 100% of a participant’s contributions up to 4% of pre-tax compensation. Participants vest immediately in their own contributions and after one year in People’s United’s contributions. A supplemental savings plan has also been established for certain senior officers and the Company has funded a trust to provide benefit payments to the extent such benefits are not paid directly by People’s United. People’s United also continues to maintain, for former First Connecticut participants who met certain eligibility requirements, a funded plan that provides supplemental retirement benefits. Combined trust assets of $54.0 million as of December 31, 2021 (which are included in other assets in the Consolidated Statements of Condition) exceeded the related combined benefit obligations of $51.5 million at that date. Expense recognized for these employee savings plans totaled $34.2 million, $35.5 million and $32.3 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation Plans	NOTE 20 – Stock-Based Compensation Plans Long-Term Incentive Plan People's United’s 2014 Plan, as amended and restated in 2017, and the predecessor 2008 Long-Term Incentive Plan (together the “Incentive Plans”) provide for awards to officers and employees in the form of: (i) incentive stock options that may afford tax benefits to recipients; (ii) non-statutory stock options that do not afford tax benefits to recipients but may provide tax benefits to People's United; and (iii) stock appreciation rights, restricted stock and performance shares. A total of 75,850,000 shares of People's United common stock are reserved for issuance under the 2014 Plan. The number of shares of common stock reserved under the 2014 Plan is depleted by one share for each option or stock appreciation right, by 5.32 shares for each restricted stock award and by 7.98 shares for each performance share. At December 31, 2021, a total of Non-statutory stock options have been granted under the Incentive Plans at exercise prices equal to the fair value of People’s United common stock at the grant dates. Option expiration dates are fixed at the grant date, with a maximum term of ten years. Prior to 2013, options granted under the Incentive Plans generally vested 50% after two years, 75% after three years and 100% after four years. Beginning in 2013, options granted under the Incentive Plans vest 33% after one year, 66% after People's United has also granted restricted stock awards under the Incentive Plans. Employees become fully vested in these shares generally after a three-year period, with requisite service conditions and no performance-based conditions to such vesting. During the vesting period, dividends are paid on the restricted stock (for grants occurring prior to February 2017) or accrued to the employees’ benefit (for grants occurring in or after February 2017) and the recipients are entitled to vote these restricted shares. The fair value of all restricted stock awards is measured at the grant date based on quoted market prices. Unvested restricted stock awards become fully vested in the event of a change in control, as defined in the Incentive Plans. People's United has also granted performance shares under the 2014 Plan. A performance share represents the right to receive a share of People’s United common stock contingent upon the Company achieving certain pre-established performance goals and the employee satisfying requisite service conditions. Employees become fully vested in these performance shares upon completion of a three-year performance period beginning with the year in which the performance shares are granted. At the end of the three-year performance period, if performance goals have been achieved, the number of performance shares earned by each employee is determined by the level of achievement against the pre-established performance goals. During the performance period, dividend equivalents are accrued to the employees' benefit. Such dividends are paid out at the end of the performance period based on the number of performance shares earned. Unvested performance shares and dividend equivalents become fully vested in the event of a change in control, as defined in the Incentive Plans. Performance Shares Awarded The following is a summary of performance share activity under the 2014 Plan: Shares Weighted-Average Unvested performance shares outstanding at December 31, 2018 1,453,372 $ 17.85 Granted 637,118 17.84 Forfeited (80,319) 18.66 Vested (505,755) 15.23 Unvested performance shares outstanding at December 31, 2019 1,504,416 18.68 Granted 691,989 16.75 Change in shares based on approved performance factors 79,623 18.60 Forfeited (55,378) 17.90 Vested (501,569) 18.60 Unvested performance shares outstanding at December 31, 2020 1,719,081 17.94 Granted 832,965 15.57 Change in shares based on approved performance factors 94,341 19.71 Forfeited (43,032) 16.44 Vested (569,476) 19.77 Unvested performance shares outstanding at December 31, 2021 2,033,879 $ 16.58 Expense related to unvested performance shares is recognized on a straight-line basis, generally over the applicable service period, and totaled $14.2 million, $11.2 million and $12.2 million for the years ended December 31, 2021, 2020 and 2019, respectively. Unamortized cost for unvested performance shares, which reflects an estimated forfeiture rate of 5% per year over the vesting period, totaled $12.3 million at December 31, 2021, and is expected to be recognized over the remaining weighted-average vesting period of 1.8 years. The fair value of performance shares vested during the years ended Recognition and Retention Plan and Stock Option Plan Following shareholder approval of the 2014 Plan in 2014, no new awards may be granted under the 2008 Long-Term Incentive Plan, the 2007 Stock Option Plan (the “SOP”) or the RRP (together the “Prior Plans”). All awards granted under the Prior Plans and the 1998 Long-Term Incentive Plan that were unvested (in the case of stock options and restricted stock awards) or unexercised (in the case of stock options) as of the date of shareholder approval of the 2014 Plan continue to be governed by the terms of the plan under which such awards were granted and the applicable grant agreements. The RRP and SOP (together the “2007 Plans”) provided for awards to directors, officers and employees in the form of: (i) incentive stock options that may afford tax benefits to recipients; (ii) non-statutory stock options that do not afford tax benefits to recipients but may provide tax benefits to People's United; and (iii) restricted stock. Shares of People's United common stock were purchased in the open market in October 2007 by a trustee with funds provided by People's United for the maximum number of shares available to be awarded in the form of restricted stock. Previously, non-statutory stock options were granted under the SOP at exercise prices equal to the fair value of People's United's common stock at the grant date based on quoted market prices. The fair value of all restricted stock awarded under the RRP was measured at the grant date based on quoted market prices. Prior to 2014, most restricted stock awards and stock options granted under the 2007 Plans were scheduled to vest in 20% annual increments over a five-year period with requisite service conditions and no performance-based conditions to such vesting. Beginning in 2014, awards made under the 2007 Plans in 2014 are scheduled to vest in one-third annual increments over a three-year period with requisite service conditions and no performance-based conditions to such vesting. During the vesting period, dividends are paid on the restricted stock and the recipients are entitled to vote these restricted shares. All restricted stock awards and stock options become fully vested and exercisable, respectively, in the event of a change of control, as defined in the 2007 Plans. Stock Options Granted People's United granted a total of 2,322,549 stock options in 2021, 3,419,934 stock options in 2020 and 2,807,692 stock options in 2019 under the Incentive Plans. The estimated weighted-average grant-date fair value of all stock options granted in 2021, 2020 and 2019 was $2.73 per option, $1.67 per option and $2.04 per option, respectively, using the Black-Scholes In arriving at the grant date fair value of stock options using the Black-Scholes option-pricing model, expected volatilities were based on the historical volatilities of People's United traded common stock. The expected term of stock options represents the period of time that options granted are expected to be outstanding. People’s United used historical data to estimate voluntary suboptimal (early) exercises by continuing employees, and estimates of post-vest option exercise or forfeiture by terminated employees. Suboptimal exercise data and employee termination estimates are incorporated into Monte Carlo simulations of People’s United common stock prices to calculate the expected term. The risk-free interest rate approximated the U.S. Treasury rate curve matched to the expected option term at the time of the grant. The following is a summary of stock option activity under the Incentive Plans and the SOP: Shares Weighted-Average Weighted-Average Aggregate Options outstanding at December 31, 2018 14,677,067 $ 15.87 Granted 2,807,692 17.62 Forfeited (652,965) 18.28 Exercised (1,632,971) 14.77 Options outstanding at December 31, 2019 15,198,823 16.20 Granted 3,419,934 16.21 Forfeited (552,726) 16.65 Exercised (43,759) 14.91 Options outstanding at December 31, 2020 18,022,272 16.19 Granted 2,322,549 15.29 Forfeited (221,074) 17.24 Exercised (2,790,967) 14.50 Options outstanding at December 31, 2021 17,332,780 $ 16.33 5.7 $ 32.4 Options exercisable at December 31, 2021 12,134,430 $ 16.46 4.6 $ 22.6 (1) Reflects only those stock options with intrinsic value at December 31, 2021. Expense relating to stock options granted is recognized on a straight-line basis, generally over the applicable service period, and totaled $5.5 million, $6.3 million and $5.2 million for the years ended December 31, 2021, 2020 and 2019, respectively. Unamortized cost for unvested stock options, which reflects an estimated forfeiture rate of 5.0% per year over Additional information concerning options outstanding and options exercisable at December 31, 2021 is summarized as follows: Exercise Price Range Options Outstanding Options Exercisable Weighted-Average Number Remaining Exercise Number Weighted-Average $11.29 — $14.71 3,708,487 2.8 $ 14.04 3,704,519 $ 14.04 14.72 — 15.75 4,565,982 6.1 15.07 2,305,988 14.85 15.76 — 18.40 5,303,025 7.7 16.81 2,368,637 17.08 18.41 — 19.71 3,755,286 5.6 19.45 3,755,286 19.45 Restricted Stock Awarded The following is a summary of restricted stock award activity under the Incentive Plans and the RRP: Shares Weighted-Average Unvested restricted shares outstanding at December 31, 2018 730,550 $ 18.03 Granted 383,420 17.44 Forfeited (68,091) 17.11 Vested (347,078) 17.49 Unvested restricted shares outstanding at December 31, 2019 698,801 18.07 Granted 562,739 14.60 Forfeited (28,090) 17.31 Vested (326,878) 18.33 Unvested restricted shares outstanding at December 31, 2020 906,572 15.85 Granted 474,766 15.29 Forfeited (54,921) 15.07 Vested (411,720) 16.59 Unvested restricted shares outstanding at December 31, 2021 914,697 $ 15.27 Expense relating to unvested restricted stock awards is recognized on a straight-line basis, generally over the applicable service period, and totaled $7.1 million, $7.8 million and $6.6 million for the years ended December 31, 2021, 2020 and 2019, respectively. Unamortized cost for unvested restricted stock awards, which reflects an estimated forfeiture rate of 5.0% per year over the vesting period, totaled $6.3 million at December 31, 2021, and is expected to be recognized over the remaining weighted-average vesting period of 1.7 years. The total fair value of restricted stock awards vested during the years ended December 31, 2021, 2020 and 2019 was $6.8 million, $5.9 million and $6.0 million, respectively. During 2021, 2020 and 2019, employees of People's United tendered a total of 119,143 shares, 117,125 shares and 115,632 shares of common stock, respectively, in satisfaction of their related minimum tax withholding obligations upon the vesting of restricted stock awards granted in prior periods and/or in payment of the exercise price and satisfaction of their related minimum tax withholding obligations upon the exercise of stock options granted in prior periods. There is no limit on the number of shares that may be tendered by employees of People's United in the future for these purposes. Shares acquired in payment of the stock option exercise price or in satisfaction of minimum tax withholding obligations are not eligible for reissuance in connection with any subsequent grants made pursuant to equity compensation plans maintained by People's United. Rather, all shares acquired in this manner are retired by People’s United, resuming the status of authorized but unissued shares of People’s United’s common stock. The total cost of shares repurchased and retired applicable to restricted stock awards during the years ended December 31, 2021, 2020 and 2019 was $2.2 million, $1.6 million and $2.0 million, respectively. Directors’ Equity Compensation Plan The People's United Financial, Inc. Directors’ Equity Compensation Plan (the “Directors’ Plan”) provides for an annual award of shares of People's United common stock with a fair value of approximately $95,000 to each non-employee director immediately following each annual meeting of shareholders. Shares of People's United common stock issued pursuant to the Directors' Plan are subject to a one-year vesting period, with no post-vesting transfer restrictions. A total of 1,492,500 shares of People's United common stock are reserved for issuance under the Directors’ Plan. In 2021, 2020 and 2019, directors were granted a total of 44,262 shares, 75,267 shares and 58,340 shares, respectively, of People’s United common stock, with grant date fair values of $19.36 per share, $11.30 per share and $16.31 per share, respectively, at those dates. Expense totaling $0.8 million for the Directors’ Plan was recognized for the year ended December 31, 2021 and $0.9 million for both of the years ended December 31, 2020 and 2019. At December 31, 2021, a total of 214,452 shares remain available for issuance.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	NOTE 21 – Fair Value Measurements Described below are the valuation methodologies used by People’s United and the resulting fair values for those financial instruments measured at fair value on both a recurring and a non-recurring basis. For those financial instruments not measured at fair value either on a recurring or non-recurring basis, disclosure of each instrument’s carrying amount and estimated fair value has been provided. Recurring Fair Value Measurements Trading Debt Securities, Equity Securities and Debt Securities Available-For-Sale When available, People’s United uses quoted market prices for identical securities received from an independent, nationally-recognized, third-party pricing service (as discussed further below) to determine the fair value of investment securities such as U.S. Treasury and agency securities and equity securities that are included in Level 1. When quoted market prices for identical securities are unavailable, People’s United uses prices provided by the independent pricing service based on recent trading activity and other observable information including, but not limited to, market interest rate curves, referenced credit spreads and estimated prepayment rates where applicable. These investments include certain U.S. and government agency debt securities, corporate and municipal debt securities and GSE mortgage-backed and CMO securities, all of which are included in Level 2. The Company’s debt securities available-for-sale are primarily comprised of GSE mortgage-backed securities. The fair value of these securities is based on prices obtained from the independent pricing service. The pricing service uses various techniques to determine pricing for the Company’s mortgage-backed securities, including option pricing and discounted cash flow analysis. The inputs include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, benchmark securities, bids, offers, reference data, monthly payment information and collateral performance. At both December 31, 2021 and 2020, the mortgage-backed securities available-for-sale portfolio was entirely comprised of GSE mortgage-backed and CMO securities with original final maturities ranging from 7 to 40 years. An active market exists for securities that are similar to the Company’s GSE mortgage-backed and CMO securities, making observable inputs readily available. Changes in the prices obtained from the pricing service are analyzed from month to month, taking into consideration changes in market conditions including changes in mortgage spreads, changes in U.S. Treasury security yields and changes in generic pricing of securities with similar duration. As a further point of validation, the Company generates its own month-end fair value estimate for all mortgage-backed securities, and state and municipal securities. While the Company has not adjusted the prices obtained from the independent pricing service, any notable differences between those prices and the Company’s estimates are subject to further analysis. This additional analysis may include a review of prices provided by other independent parties, a yield analysis, a review of average life changes using Bloomberg analytics and a review of historical pricing for the particular security. Based on management’s review of the prices provided by the pricing service, the fair values incorporate observable market inputs used by market participants at the measurement date and, as such, are classified as Level 2 securities. Other Assets As discussed in Note 19, certain unfunded nonqualified supplemental plans have been established to provide retirement benefits to certain senior officers. People’s United has funded two trusts to provide benefit payments to the extent such benefits are not paid directly by People’s United, the assets of which are included in other assets in the Consolidated Statements of Condition. When available, People’s United determines the fair value of the trust assets using quoted market prices for identical securities received from a third-party nationally recognized pricing service. Derivatives People’s United values its derivatives using internal models that are based on market or observable inputs, including interest rate curves and forward/spot prices for selected currencies. Derivative assets and liabilities included in Level 2 represent interest rate swaps and caps, foreign exchange contracts, risk participation agreements, forward commitments to sell residential mortgage loans and interest rate-lock commitments on residential mortgage loans. The following tables summarize People’s United’s financial instruments that are measured at fair value on a recurring basis: Fair Value Measurements Using As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Debt securities available-for-sale: U.S. Treasury and agency $ 636.7 $ — $ — $ 636.7 GSE mortgage-backed and CMO securities — 6,007.3 — 6,007.3 Other assets: Exchange-traded funds 89.2 — — 89.2 Mutual funds 5.3 — — 5.3 Interest rate swaps — 384.0 — 384.0 Interest rate caps — 1.7 — 1.7 Foreign exchange contracts — 2.4 — 2.4 Forward commitments to sell residential — — — — Total $ 731.2 $ 6,395.4 $ — $ 7,126.6 Financial liabilities: Interest rate swaps $ — $ 90.8 $ — $ 90.8 Interest rate caps — 1.7 — 1.7 Risk participation agreements — 0.2 — 0.2 Foreign exchange contracts — 2.6 — 2.6 Interest rate-lock commitments on residential — — — — Total $ — $ 95.3 $ — $ 95.3 Fair Value Measurements Using As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Debt securities available-for-sale: U.S. Treasury and agency $ 541.6 $ — $ — $ 541.6 GSE mortgage-backed securities — 4,383.9 — 4,383.9 Equity securities 5.3 — — 5.3 Other assets: Exchange-traded funds 53.0 — — 53.0 Mutual funds 3.9 — — 3.9 Interest rate swaps — 783.8 — 783.8 Interest rate caps — 3.0 — 3.0 Foreign exchange contracts — 12.8 — 12.8 Forward commitments to sell residential mortgage loans — 0.7 — 0.7 Total $ 603.8 $ 5,184.2 $ — $ 5,788.0 Financial liabilities: Interest rate swaps $ — $ 157.2 $ — $ 157.2 Interest rate caps — 3.0 — 3.0 Risk participation agreements — 0.4 — 0.4 Foreign exchange contracts — 8.8 — 8.8 Interest rate-lock commitments on residential mortgage loans — 1.0 — 1.0 Total $ — $ 170.4 $ — $ 170.4 (1) Fair value totaled less than $0.1 million at December 31, 2021. Non-Recurring Fair Value Measurements The valuation techniques and inputs used by People's United for those assets measured at fair value on a non-recurring basis, excluding goodwill, are described below. Loans Held-for-Sale Loans held-for-sale are recorded at the lower of amortized cost or fair value and are therefore measured at fair value on a Collateral Dependent Loans The Company’s approach to determining the fair value of collateral dependent loans is described in Note 1, “Summary of Significant Accounting Policies”. People’s United has estimated the fair values of these assets using Level 3 inputs, such as discounted cash flows based on inputs that are largely unobservable and, instead, reflect management’s own estimates of the assumptions a market participant would use in pricing such loans and/or the fair value of collateral based on independent third-party appraisals for collateral dependent loans. Such appraisals are based on the market and/or income approach to value and are subject to a discount REO and Repossessed Assets REO and repossessed assets are recorded at the lower of cost or fair value, less estimated selling costs, and are therefore measured at fair value on a non-recurring basis. People’s United has estimated the fair values of these assets using Level 3 inputs, such as independent third-party appraisals and price opinions. Such appraisals are based on the market and/or income approach to value and are subject to a discount (to reflect estimated cost to sell) that generally approximates 10%. Assets that are acquired through loan default are recorded as held-for-sale initially at the lower of the recorded investment in the loan or fair value (less estimated selling costs) upon the date of foreclosure/repossession. Subsequent to foreclosure/repossession, valuations are updated periodically and the carrying amounts of these assets may be reduced further. Mortgage Servicing Rights Mortgage servicing rights are evaluated for impairment based upon the fair value of the servicing rights as compared to their amortized cost. The fair value of mortgage servicing rights is based on a valuation model that calculates the present value of estimated net servicing income. This model incorporates certain assumptions that market participants would likely use in estimating future net servicing income, such as interest rates, prepayment speeds and the cost to service (including delinquency and foreclosure costs), all of which require a degree of management judgment. Adjustments are only recorded when the discounted cash flows derived from the valuation model are less than the carrying value of the asset. As such, mortgage servicing rights are subject to measurement at fair value on a non-recurring basis and are classified as Level 3 assets. The following tables summarize People’s United’s assets that are measured at fair value on a non-recurring basis: Fair Value Measurements Using As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Loans held-for-sale (1) $ — $ 8.8 $ — $ 8.8 Collateral dependent loans (2) — — 25.3 25.3 REO and repossessed assets (3) — — 5.1 5.1 Mortgage servicing rights (4) — — 4.3 4.3 Total $ — $ 8.8 $ 34.7 $ 43.5 Fair Value Measurements Using As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Goodwill (5) $ — $ — $ 2,680.8 $ 2,680.8 Loans held-for-sale (1) — 26.5 — 26.5 Collateral dependent loans (2) — — 32.8 32.8 REO and repossessed assets (3) — — 12.5 12.5 Mortgage servicing rights (4) — — 4.8 4.8 Total $ — $ 26.5 $ 2,730.9 $ 2,757.4 (1) Consists of residential mortgage loans; no fair value adjustments were recorded for the years ended December 31, 2021 and 2020. (2) Represents the recorded investment in collateral dependent loans with a related ACL totaling $13.6 million and $20.5 million at December 31, 2021 and 2020, respectively, measured in accordance with applicable accounting guidance. The provision for credit losses on collateral dependent loans totaled $3.6 million and $22.0 million for the years ended December 31, 2021 and 2020, respectively. (3) Represents: (i) $3.7 million of repossessed assets and (ii) $1.4 million of residential REO at December 31, 2021. (4) Fair value adjustments totaling $(0.5) million and $(5.8) million were recorded for the years ended December 31, 2021 and 2020, respectively. (5) Goodwill was evaluated for impairment as of October 1, 2020 (the Company’s annual measurement date) (see Note 8). Financial Assets and Financial Liabilities Not Measured At Fair Value The following tables summarize the carrying amounts, estimated fair values and placement in the fair value hierarchy of People’s United’s financial instruments that are not measured at fair value either on a recurring or non-recurring basis: Carrying Estimated Fair Value As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Cash and due from banks $ 320.5 $ 320.5 $ — $ — $ 320.5 Short-term investments 10,268.8 — 10,268.8 — 10,268.8 Debt securities held-to-maturity, net 3,841.5 — 4,034.6 1.5 4,036.1 FRB and FHLB stock 264.6 — 264.6 — 264.6 Total loans, net (1) 37,482.4 — 6,906.6 30,636.5 37,543.1 Financial liabilities: Time deposits 3,696.7 — 3,703.3 — 3,703.3 Other deposits 50,058.6 — 50,058.6 — 50,058.6 FHLB advances 562.6 — 562.7 — 562.7 Customer repurchase agreements 395.2 — 395.2 — 395.2 Notes and debentures 992.8 — 1,010.6 — 1,010.6 Carrying Estimated Fair Value As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Cash and due from banks $ 477.3 $ 477.3 $ — $ — $ 477.3 Short-term investments 3,766.0 — 3,766.0 — 3,766.0 Debt securities held-to-maturity 3,993.8 — 4,265.5 1.5 4,267.0 FRB and FHLB stock 266.6 — 266.6 — 266.6 Total loans, net (1) 43,411.6 — 8,539.4 35,294.0 43,833.4 Financial liabilities: Time deposits 5,658.8 — 5,699.7 — 5,699.7 Other deposits 46,478.9 — 46,478.9 — 46,478.9 FHLB advances 569.7 — 570.3 — 570.3 Customer repurchase agreements 452.9 — 452.9 — 452.9 Federal funds purchased 125.0 — 125.0 — 125.0 Notes and debentures 1,009.6 — 1,035.8 — 1,035.8 (1) Excludes collateral dependent loans measured at fair value on a non-recurring basis totaling $25.3 million and $32.8 million at December 31, 2021 and 2020, respectively.

Legal Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	NOTE 22 – Legal Proceedings In the normal course of business, People’s United is subject to various legal proceedings. Management has discussed with legal counsel the nature of these legal proceedings and, based on the advice of counsel and the information currently available, believes that the eventual outcome of these legal proceedings will not have a material adverse effect on People’s United’s financial condition, results of operations or liquidity.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2021
Investments, All Other Investments [Abstract]
Financial Instruments	NOTE 23 – Financial Instruments In the normal course of business, People’s United is a party to both on-balance-sheet and off-balance-sheet financial instruments involving, to varying degrees, elements of credit risk and IRR in addition to the amounts recognized in the Consolidated Statements of Condition. The contractual amounts of off-balance-sheet instruments reflect the extent of People’s United’s involvement in particular classes of financial instruments. A summary of the contractual or notional amounts of People’s United’s lending-related and derivative financial instruments follows: As of December 31 (in millions) 2021 2020 Lending-Related Financial Instruments: (1) Loan origination commitments and unadvanced lines of credit: Commercial and industrial $ 8,332.8 $ 6,723.5 Home equity and other consumer 3,536.5 3,349.5 Commercial real estate 795.1 962.4 Equipment financing 655.6 437.6 Residential mortgage 18.9 44.6 Letters of credit: Stand-by 156.0 150.4 Commercial 4.2 4.5 Derivative Financial Instruments: (2) Interest rate swaps: For market risk management 925.0 925.0 For commercial customers: Customer 8,469.9 8,878.6 Institutional counterparties 8,478.3 8,881.3 Interest rate caps: For commercial customers: Customer 163.7 185.1 Institutional counterparties 163.7 185.1 Risk participation agreements 903.2 924.3 Foreign exchange contracts 321.8 285.3 Forward commitments to sell residential mortgage loans 0.7 25.4 Interest rate-lock commitments on residential mortgage loans 0.7 41.5 (1) The contractual amounts of these financial instruments represent People’s United’s maximum potential exposure to credit loss, assuming: (i) the instruments are fully funded at a later date; (ii) the borrower does not meet contractual repayment obligations; and (iii) any collateral or other security proves to be worthless. (2) The contractual or notional amounts of these financial instruments are substantially greater than People’s United’s maximum potential exposure to credit loss. Lending-Related Financial Instruments The contractual amounts of People’s United’s lending-related financial instruments do not necessarily represent future cash requirements since certain of these instruments may expire without being funded and others may not be fully drawn upon. These instruments are subject to People’s United’s credit approval process, including an evaluation of the customer’s creditworthiness and related collateral requirements. Commitments generally have fixed expiration dates or other termination clauses and may require the payment of a fee by the customer. The geographic distribution of People’s United’s lending-related financial instruments is similar to the distribution of its loan portfolio as described in Note 5. People’s United issues both stand-by and commercial letters of credit. Stand-by letters of credit are conditional commitments issued by People’s United to guarantee the performance of a customer to a third party. The letter of credit is generally extended for an average term of one year and is secured in a manner similar to existing extensions of credit. For each letter of credit issued, if the customer fails to perform under the terms of the agreement, People’s United would have to fulfill the terms of the letter of credit. The credit risk involved in issuing stand-by letters of credit is essentially the same as that involved in extending loan facilities to customers. A commercial letter of credit is normally a short-term instrument issued by a financial institution on behalf of its customer. The letter of credit authorizes a beneficiary to draw drafts on the financial institution or one of its correspondent banks, provided the terms and conditions of the letter of credit have been met. In issuing a commercial letter of credit, the financial institution has substituted its credit standing for that of its customer. After drafts are paid by the financial institution, the customer is charged or an obligation is created under an existing reimbursement agreement. An advance under a reimbursement agreement is recorded as a loan by the financial institution and is subject to terms and conditions similar to other commercial obligations. The fair value of People’s United’s obligations relating to its unfunded loan commitments and letters of credit was $28.4 million and $26.9 million at December 31, 2021 and 2020, respectively, and is included in other liabilities in the Consolidated Statements of Condition (see Note 6). Derivative Financial Instruments and Hedging Activities People’s United uses derivative financial instruments as components of its market risk management (principally to manage IRR). Certain other derivatives are entered into in connection with transactions with commercial customers. Derivatives are not used for speculative purposes. By using derivatives, People’s United is exposed to credit risk to the extent that counterparties to the derivative contracts do not perform as required. Should a counterparty fail to perform under the terms of a derivative contract, the Company’s counterparty credit risk is equal to the amount reported as a derivative asset in the Consolidated Statements of Condition. In accordance with the Company’s balance sheet offsetting policy (see Note 1), amounts reported as derivative assets represent derivative contracts in a gain position, without consideration for derivative contracts in a loss position with the same counterparty (to the extent subject to master netting arrangements) and posted collateral. People’s United seeks to minimize counterparty credit risk through credit approvals, limits, monitoring procedures, execution of master netting arrangements and obtaining collateral, where appropriate. Counterparties to People’s United’s derivatives include major financial institutions and exchanges that undergo comprehensive and periodic internal credit analysis as well as maintain investment grade credit ratings from the major credit rating agencies. As such, management believes the risk of incurring credit losses on derivative contracts with those counterparties is remote and losses, if any, would be immaterial. Certain of People’s United’s derivative contracts contain provisions establishing collateral requirements (subject to minimum collateral posting thresholds) based on the Company’s external credit rating. If the Company’s senior unsecured debt rating were to fall below the level generally recognized as investment grade, the counterparties to such derivative contracts could require additional collateral on those derivative transactions in a net liability position (after considering the effect of master netting arrangements and posted collateral). There were no derivative instruments with such credit-related contingent features that were in a net liability position at December 31, 2021. The following sections further discuss each class of derivative financial instrument used by People’s United, including management’s principal objectives and risk management strategies. Interest Rate Swaps People’s United may, from time to time, enter into interest rate swaps that are used to manage IRR associated with certain interest-earning assets and interest-bearing liabilities. The Bank has entered into a pay floating/receive fixed interest rate swap to hedge the change in fair value due to changes in interest rates of the Bank’s $400 million subordinated notes. The Bank has agreed with the swap counterparty to exchange, at specified intervals, the difference between fixed-rate and floating-rate interest amounts calculated based on a notional amount of $375 million. The fixed-rate interest payments received on the swap will essentially offset the fixed-rate interest payments made on these notes, notwithstanding the notional difference between these notes and the swap. The floating-rate interest amounts paid under the swap are calculated based on three-month LIBOR plus 126.5 basis points. The swap effectively converts the fixed-rate subordinated notes to a floating-rate liability. This swap is accounted for as a fair value hedge. The Bank has entered into two-year and three-year pay fixed/receive floating interest rate swaps to reduce its interest rate exposure by hedging the variability in interest cash flows on certain rolling three-month funding liabilities, which may consist of FHLB advances. The Bank has agreed with the swap counterparty to exchange, at specified intervals, the difference between fixed-rate and floating-rate interest amounts calculated based on an aggregate notional amount of $550 million. The interest rate swaps effectively convert a short-term benchmark interest rate (LIBOR) into a fixed-rate. These swaps are accounted for as cash flow hedges. Customer Derivatives People’s United enters into interest rate swaps and caps with certain of its commercial customers. In order to minimize its risk, these customer interest rate swaps (pay floating/receive fixed) and caps have been offset with essentially matching interest rate swaps (pay fixed/receive floating) and caps with People’s United’s institutional counterparties. Hedge accounting has not been applied for these derivatives. Accordingly, changes in the fair value of all such interest rate swaps and caps are recognized in current earnings. Foreign Exchange Contracts Foreign exchange contracts are commitments to buy or sell foreign currency on a future date at a contractual price. People’s United uses these instruments on a limited basis to (i) eliminate its exposure to fluctuations in currency exchange rates on certain of its commercial loans that are denominated in foreign currencies and (ii) provide foreign exchange contracts on behalf of commercial customers within credit exposure limits. Gains and losses on foreign exchange contracts substantially offset the translation gains and losses on the related loans. Risk Participation Agreements People’s United enters into risk participation agreements under which it may either assume or sell credit risk associated with a borrower’s performance under certain interest rate derivative contracts. In those instances in which People’s United has assumed credit risk, it is not a party to the derivative contract and has entered into the risk participation agreement because it is also a party to the related loan agreement with the borrower. In those instances in which People’s United has sold credit risk, it is a party to the derivative contract and has entered into the risk participation agreement because it sold a portion of the related loan. People’s United manages its credit risk under risk participation agreements by monitoring the creditworthiness of the borrower, based on its normal credit review process. The notional amounts of the risk participation agreements reflect People’s United’s pro-rata share of the derivative contracts, consistent with its share of the related loans. Forward Commitments to Sell Residential Mortgage Loans and Related Interest Rate-Lock Commitments People’s United enters into forward commitments to sell adjustable-rate and fixed-rate residential mortgage loans (all to be sold servicing released) in order to reduce the market risk associated with originating loans for sale in the secondary market. In order to fulfill a forward commitment, People’s United delivers originated loans at prices or yields specified by the contract. The risks associated with such contracts arise from the possible inability of counterparties to meet the contract terms or People’s United’s inability to originate the necessary loans. Gains and losses realized on the forward contracts are reported in the Consolidated Statements of Income as a component of the net gains on sales of residential mortgage loans. In the normal course of business, People’s United will commit to an interest rate on a mortgage loan application at the time of application, or anytime thereafter. The risks associated with these interest rate-lock commitments arise if market interest rates change prior to the closing of these loans. Both forward sales commitments and interest rate-lock commitments made to borrowers on held-for-sale loans are accounted for as derivatives, with changes in fair value recognized in current earnings. Interest Rate Locks In connection with its planned issuance of senior notes in the fourth quarter of 2012, People’s United entered into The table below provides a summary of the notional amounts and fair values (presented on a gross basis) of derivatives outstanding: Fair Values (1) Type of Notional Amounts Assets Liabilities As of December 31 (in millions) 2021 2020 2021 2020 2021 2020 Derivatives Not Designated as Hedging Interest rate swaps: Commercial customers N/A $ 8,469.9 $ 8,878.6 $ 359.7 $ 778.0 $ 15.8 $ 0.4 Institutional counterparties N/A 8,478.3 8,881.3 24.3 5.8 75.0 156.8 Interest rate caps: Commercial customers N/A 163.7 185.1 1.4 3.0 0.3 — Institutional counterparties N/A 163.7 185.1 0.3 — 1.4 3.0 Risk participation agreements N/A 903.2 924.3 — — 0.2 0.4 Foreign exchange contracts N/A 321.8 285.3 2.4 12.8 2.6 8.8 Forward commitments to sell N/A 0.7 25.4 — 0.7 — — Interest rate-lock commitments on N/A 0.7 41.5 — — — 1.0 Total 388.1 800.3 95.3 170.4 Derivatives Designated as Hedging Interest rate swaps: FHLB advances Cash flow 550.0 550.0 — — — — Subordinated notes Fair value 375.0 375.0 — — — — Total — — — — Total fair value of $ 388.1 $ 800.3 $ 95.3 $ 170.4 (1) Assets are recorded in other assets and liabilities are recorded in other liabilities. (2) Fair value totaled less than $0.1 million at December 31, 2021. The following table summarizes the impact of People’s United’s derivatives on pre-tax income and AOCL: Type of Amount of Pre-Tax Gain (Loss) Amount of Pre-Tax Gain (Loss) Years ended December 31 (in millions) 2021 2020 2019 2021 2020 2019 Derivatives Not Designated as Interest rate swaps: Commercial customers N/A $ (236.3) $ 614.8 $ 374.9 $ — $ — $ — Institutional counterparties N/A 241.1 (599.4) (350.3) — — — Interest rate caps: Commercial customers N/A (1.2) 1.4 1.4 — — — Institutional counterparties N/A 1.8 (1.4) (1.5) — — — Foreign exchange contracts N/A 1.4 1.0 1.0 — — — Risk participation agreements N/A 0.1 (0.5) (0.4) — — — Forward commitments to sell N/A (0.7) 0.3 0.3 — — — Interest rate-lock commitments on N/A 1.0 (0.5) (0.4) — — — Total 7.2 15.7 25.0 — — — Derivatives Designated as Interest rate swaps Fair value 9.7 5.9 0.3 — — — Interest rate swaps Cash flow (1.9) 1.9 (1.2) 1.2 (1.3) 1.9 Interest rate locks Cash flow 0.1 0.1 0.1 — — — Total 7.9 7.9 (0.8) 1.2 (1.3) 1.9 Total $ 15.1 $ 23.6 $ 24.2 $ 1.2 $ (1.3) $ 1.9 (1) Amounts recognized in earnings are recorded in interest income, interest expense or other non-interest income for derivatives designated as hedging instruments and in other non-interest income for derivatives not designated as hedging instruments.

Balance Sheet Offsetting

Balance Sheet Offsetting	12 Months Ended
	Dec. 31, 2021
Offsetting [Abstract]
Balance Sheet Offsetting	NOTE 24 – Balance Sheet Offsetting The Chicago Mercantile Exchange (“CME”) legally characterizes variation margin payments for over-the-counter derivatives that clear as settlements rather than collateral. Accordingly, the Company’s accounting policies classify, for accounting and presentation purposes, variation margin payments deemed to be legal settlements as a single unit of account with the related derivative(s). At both December 31, 2021 and 2020, this presentation impacted one of the Company’s institutional counterparties. As such, People’s United has, subject to the corresponding enforceable master netting arrangement, netted the institutional counterparty’s CME derivative position and offset the counterparty’s variation margin payments in the Consolidated Statement of Condition as of both dates. The following tables provide a gross presentation, the effects of offsetting, and a net presentation of the Company’s financial instruments that are eligible for offset in the Consolidated Statements of Condition. The collateral amounts in these tables are limited to the outstanding balances of the related asset or liability (after netting is applied) and, therefore, instances of overcollateralization are not presented. In the tables below, the Net Amount Presented of the derivative assets and liabilities can be reconciled to the fair value of the Company’s derivative financial instruments in Note 23. The Company’s derivative contracts with commercial customers and customer repurchase agreements are not subject to master netting arrangements and, therefore, have been excluded from the tables below. Gross Gross Net Gross Amounts Not Offset Net As of December 31, 2021 (in millions) Financial Collateral Financial assets: Interest rate swaps/caps: Counterparty A $ 0.1 $ — $ 0.1 $ (0.1) $ — $ — Counterparty B — — — — — — Counterparty C 1.7 — 1.7 (1.7) — — Counterparty D 0.6 — 0.6 (0.6) — — Counterparty E 20.0 — 20.0 — — 20.0 Other counterparties 2.2 — 2.2 (1.7) (0.4) 0.1 Foreign exchange contracts 2.4 — 2.4 — — 2.4 Total $ 27.0 $ — $ 27.0 $ (4.1) $ (0.4) $ 22.5 Financial liabilities: Interest rate swaps/caps: Counterparty A $ 2.3 $ — $ 2.3 $ (0.1) $ (2.2) $ — Counterparty B 3.6 — 3.6 — (3.6) — Counterparty C 28.8 — 28.8 (1.7) (27.1) — Counterparty D 9.6 — 9.6 (0.6) (8.7) 0.3 Counterparty E — — — — — — Other counterparties 32.1 — 32.1 (1.7) (30.4) — Foreign exchange contracts 2.6 — 2.6 — — 2.6 Total $ 79.0 $ — $ 79.0 $ (4.1) $ (72.0) $ 2.9 Gross Gross Net Gross Amounts Not Offset Net As of December 31, 2020 (in millions) Financial Collateral Financial assets: Interest rate swaps/caps: Counterparty A $ — $ — $ — $ — $ — $ — Counterparty B — — — — — — Counterparty C 0.3 — 0.3 (0.3) — — Counterparty D — — — — — — Counterparty E 5.4 — 5.4 — — 5.4 Other counterparties 0.1 — 0.1 (0.1) — — Foreign exchange contracts 12.8 — 12.8 — — 12.8 Total $ 18.6 $ — $ 18.6 $ (0.4) $ — $ 18.2 Financial liabilities: Interest rate swaps/caps: Counterparty A $ 5.6 $ — $ 5.6 $ — $ (5.6) $ — Counterparty B 7.1 — 7.1 — (7.1) — Counterparty C 56.6 — 56.6 (0.3) (56.3) — Counterparty D 21.4 — 21.4 — (10.4) 11.0 Counterparty E — — — — — — Other counterparties 69.1 — 69.1 (0.1) (69.0) — Foreign exchange contracts 8.8 — 8.8 — — 8.8 Total $ 168.6 $ — $ 168.6 $ (0.4) $ (148.4) $ 19.8 The following tables show the extent to which assets and liabilities exchanged under resale and repurchase agreements have been offset in the Consolidated Statements of Condition. These agreements: (i) are entered into simultaneously with the same financial institution counterparty; (ii) have the same principal amounts and inception/maturity dates; and (iii) are subject to a master netting arrangement that contains a conditional right of offset upon default. At December 31, 2021 and 2020, the Company posted as collateral marketable securities with fair values of $252.9 million and $258.7 million, respectively, and, in turn, accepted as collateral marketable securities with fair values of $258.9 million and $254.4 million, respectively. As of December 31, 2021 (in millions) Gross Gross Net Total resale agreements $ 250.0 $ (250.0) $ — Total repurchase agreements $ 250.0 $ (250.0) $ — As of December 31, 2020 (in millions) Gross Gross Net Total resale agreements $ 250.0 $ (250.0) $ — Total repurchase agreements $ 250.0 $ (250.0) $ —

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Segment Information	NOTE 25 – Segment Information Public companies are required to report (i) certain financial and descriptive information about “reportable operating segments,” as defined, and (ii) certain enterprise-wide financial information about products and services, geographic areas and major customers. Operating segment information is reported using a “management approach” that is based on the way management organizes the segments for purposes of making operating decisions and assessing performance. People’s United’s operations are divided into three primary operating segments that represent its core businesses: Commercial Banking; Retail Banking; and Wealth Management. In addition, the Treasury area manages People’s United’s securities portfolio, short-term investments, brokered deposits, wholesale borrowings and the funding center. The Company’s operating segments have been aggregated into two reportable segments: Commercial Banking and Retail Banking. These reportable segments have been identified and organized based on the nature of the underlying products and services applicable to each segment, the type of customers to whom those products and services are offered and the distribution channel through which those products and services are made available. With respect to the Company’s traditional wealth management activities, this presentation results in the allocation of the Company’s insurance business (prior to its sale in November 2020) and certain trust activities to the Commercial Banking segment, and the allocation of the Company’s brokerage business and certain other trust activities to the Retail Banking segment. Commercial Banking consists principally of commercial real estate lending, middle market and business banking, equipment financing, and mortgage warehouse and asset-based lending. This segment also provides treasury management services, capital market capabilities and commercial deposit products. Commercial insurance services were previously provided through PUIA (see Note 2). Retail Banking includes, as its principal business lines, consumer lending (including residential mortgage and home equity lending) and consumer deposit gathering activities. This segment also includes brokerage, financial advisory services, investment management services and life insurance provided by PSI, investment advisory services and financial management and planning services provided by PUA and non-institutional trust services. People’s United’s segment disclosure is based on an internal profitability reporting system, which generates information by operating segment based on a series of management estimates and allocations regarding funds transfer pricing (“FTP”), the provision for credit losses on loans, non-interest expense and income taxes. These estimates and allocations, some of which are subjective in nature, are subject to periodic review and refinement. Any changes in estimates and allocations that may affect the reported results of any segment will not affect the consolidated financial position or results of operations of People’s United as a whole. FTP, which is used in the calculation of each operating segment’s net interest income, measures the value of funds used in and provided by an operating segment. The difference between the interest income on earning assets and the interest expense on funding liabilities, and the corresponding FTP charge for interest income or credit for interest expense, results in net spread income. For fixed-term assets and liabilities, the FTP rate is assigned at the time the asset or liability is originated by reference to the Company’s FTP yield curve, which is updated daily. For non-maturity-term assets and liabilities, the FTP rate is determined based upon the underlying characteristics, or behavior, of each particular product and results in the use of a historical rolling average FTP rate determined over a period that is most representative of the average life of the particular asset or liability. While the Company’s FTP methodology serves to remove IRR from the operating segments and better facilitate pricing decisions, thereby allowing management to assess the longer-term profitability of an operating segment more effectively, it may, in sustained periods of low and/or high interest rates, result in a measure of operating segment net interest income that is not reflective of current interest rates. A five-year rolling average net charge-off rate is used as the basis for the provision for credit losses on loans for the respective operating segment in order to present a level of portfolio credit cost that is representative of the Company’s historical experience, without presenting the potential volatility from year-to-year changes in credit conditions. While this method of allocation allows management to assess the longer-term profitability of an operating segment more effectively, it may result in a measure of an operating segment’s provision for credit losses on loans that does not reflect actual losses for the periods presented. The provision for credit losses for Treasury reflects the application of the CECL standard (see Note 4). People’s United allocates a majority of non-interest expenses to each operating segment using a full-absorption costing process (i.e. all expenses are fully-allocated to the segments). Direct and indirect costs are analyzed and pooled by process and assigned to the appropriate operating segment and corporate overhead costs are allocated to the operating segments. Income tax expense is allocated to each operating segment using a constant rate, based on an estimate of the consolidated effective income tax rate for the year. Average total assets and average total liabilities are presented for each reportable segment due to management’s reliance, in part, on such average balances for purposes of assessing segment performance. Average total assets of each reportable segment include allocated goodwill and intangible assets, both of which are reviewed for impairment at least annually. The "Other" category includes the residual financial impact from the allocation of revenues and expenses (including the provision for credit losses on loans) and certain revenues and expenses not attributable to a particular segment; assets and liabilities not attributable to a particular segment; reversal of the FTE adjustment since net interest income for each segment is presented on an FTE basis; and the FTP impact from excess capital. The "Other" category also includes certain gains totaling $3.9 million, $75.9 million and $10.9 million for the years ended December 31, 2021, 2020 and 2019, respectively (included in non-interest income), and certain charges totaling $47.8 million, $45.9 million and $65.6 million for the years ended December 31, 2021, 2020 and 2019, respectively (included in non-interest expense). The following tables provide selected financial information for People’s United’s reportable segments: Year ended December 31, 2021 (in millions) Commercial Retail Total Treasury Other Total Net interest income (loss) $ 1,145.1 $ 677.6 $ 1,822.7 $ (317.8) $ (5.8) $ 1,499.1 Provision for credit losses 52.9 8.5 61.4 (0.1) (109.6) (48.3) Total non-interest income 172.4 195.7 368.1 14.8 10.7 393.6 Total non-interest expense 452.0 651.8 1,103.8 2.4 77.6 1,183.8 Income (loss) before income tax 812.6 213.0 1,025.6 (305.3) 36.9 757.2 Income tax expense (benefit) 162.8 42.6 205.4 (61.0) 7.9 152.3 Net income (loss) $ 649.8 $ 170.4 $ 820.2 $ (244.3) $ 29.0 $ 604.9 Average total assets $ 33,644.4 $ 10,923.9 $ 44,568.3 $ 17,946.9 $ 1,737.9 $ 64,253.1 Average total liabilities 19,466.3 28,915.0 48,381.3 7,274.9 893.9 56,550.1 Year ended December 31, 2020 (in millions) Commercial Retail Total Treasury Other Total Net interest income (loss) $ 1,098.9 $ 634.9 $ 1,733.8 $ (118.5) $ (39.5) $ 1,575.8 Provision for credit losses 52.8 10.0 62.8 (0.3) 93.3 155.8 Total non-interest income 217.3 182.2 399.5 7.8 85.4 492.7 Total non-interest expense (1) 478.5 1,009.4 1,487.9 3.7 72.5 1,564.1 Income (loss) before income tax 784.9 (202.3) 582.6 (114.1) (119.9) 348.6 Income tax expense (benefit) 144.7 27.4 172.1 (19.8) (23.3) 129.0 Net income (loss) $ 640.2 $ (229.7) $ 410.5 $ (94.3) $ (96.6) $ 219.6 Average total assets $ 35,946.3 $ 13,447.3 $ 49,393.6 $ 9,988.1 $ 1,656.4 $ 61,038.1 Average total liabilities 16,524.6 26,978.3 43,502.9 8,863.8 859.6 53,226.3 (1) Retail Banking includes a $353.0 million non-cash goodwill impairment charge (see Note 8). Year ended December 31, 2019 (in millions) Commercial Retail Total Treasury Other Total Net interest income (loss) $ 807.1 $ 555.1 $ 1,362.2 $ 66.5 $ (16.4) $ 1,412.3 Provision for credit losses 44.1 8.9 53.0 — (24.7) 28.3 Total non-interest income 206.5 195.9 402.4 14.1 14.6 431.1 Total non-interest expense 448.7 600.2 1,048.9 13.8 100.0 1,162.7 Income (loss) before income tax 520.8 141.9 662.7 66.8 (77.1) 652.4 Income tax expense (benefit) 104.3 28.5 132.8 13.5 (14.3) 132.0 Net income (loss) $ 416.5 $ 113.4 $ 529.9 $ 53.3 $ (62.8) $ 520.4 Average total assets $ 29,746.8 $ 12,560.9 $ 42,307.7 $ 7,882.3 $ 1,468.0 $ 51,658.0 Average total liabilities 11,490.2 23,397.7 34,887.9 9,011.9 686.9 44,586.7

Parent Company Financial Inform

Parent Company Financial Information	12 Months Ended
	Dec. 31, 2021
Condensed Financial Information Disclosure [Abstract]
Parent Company Financial Information	NOTE 26 – Parent Company Financial Information Condensed financial information of People’s United (parent company only) is presented below: CONDENSED STATEMENTS OF CONDITION As of December 31 (in millions) 2021 2020 Assets: Cash at bank subsidiary $ 490.2 $ 305.3 Total cash and cash equivalents 490.2 305.3 Equity securities, at fair value — 5.3 Investments in subsidiaries: Bank subsidiary 7,775.6 7,600.3 Non-bank subsidiaries 10.1 7.3 Goodwill 203.0 203.0 Due from bank subsidiary 5.8 3.1 Other assets 0.2 62.2 Total assets $ 8,484.9 $ 8,186.5 Liabilities and Stockholders’ Equity: Notes and debentures $ 578.4 $ 579.1 Other liabilities 4.7 4.6 Stockholders’ equity 7,901.8 7,602.8 Total liabilities and stockholders’ equity $ 8,484.9 $ 8,186.5 CONDENSED STATEMENTS OF INCOME Years ended December 31 (in millions) 2021 2020 2019 Revenues: Dividend income from subsidiaries: Bank subsidiary $ 437.0 $ 498.0 $ 457.0 Non-bank subsidiaries 2.5 — — Interest income 0.1 0.3 0.4 Non-interest income 1.1 (0.8) 1.7 Total revenues 440.7 497.5 459.1 Expenses: Interest on notes and debentures 21.7 21.7 19.2 Non-interest expense 20.0 8.5 14.1 Total expenses 41.7 30.2 33.3 Income before income tax benefit and subsidiaries 399.0 467.3 425.8 Income tax benefit (8.5) (6.5) (6.2) Income before subsidiaries undistributed income 407.5 473.8 432.0 Subsidiaries undistributed income (distributions in excess of income) 197.4 (254.2) 88.4 Net income $ 604.9 $ 219.6 $ 520.4 CONDENSED STATEMENTS OF COMPREHENSIVE INCOME Years ended December 31 (in millions) 2021 2020 2019 Net income $ 604.9 $ 219.6 $ 520.4 Other comprehensive (loss) income, net of tax: Net unrealized losses on derivatives accounted for as cash flow hedges (0.1) (0.1) (0.1) Other comprehensive (loss) income of bank subsidiary (47.5) 77.8 90.0 Total other comprehensive (loss) income, net of tax (47.6) 77.7 89.9 Total comprehensive income $ 557.3 $ 297.3 $ 610.3 CONDENSED STATEMENTS OF CASH FLOWS Years ended December 31 (in millions) 2021 2020 2019 Cash Flows from Operating Activities: Net income $ 604.9 $ 219.6 $ 520.4 Adjustments to reconcile net income to net cash provided Subsidiaries (undistributed income) distributions in excess of income (197.4) 254.2 (88.4) Net change in other assets and other liabilities 58.4 (2.1) (0.7) Net cash provided by operating activities 465.9 471.7 431.3 Cash Flows from Investing Activities: Proceeds from sales of equity securities 6.4 2.0 1.6 Net cash provided by investing activities 6.4 2.0 1.6 Cash Flows from Financing Activities: Cash dividends paid on common stock (307.8) (304.1) (274.8) Cash dividends paid on preferred stock (14.1) (14.1) (14.1) Common stock repurchases (2.1) (306.1) (4.5) Proceeds from stock options exercised 36.6 0.7 24.1 Net cash used in financing activities (287.4) (623.6) (269.3) Net increase (decrease) in cash and cash equivalents 184.9 (149.9) 163.6 Cash and cash equivalents at beginning of year 305.3 455.2 291.6 Cash and cash equivalents at end of year $ 490.2 $ 305.3 $ 455.2

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Event	NOTE 27 – Subsequent Event On February 18, 2022, People’s United and M&T jointly announced that the two companies have agreed to extend their merger agreement from February 21, 2022 to June 1, 2022 in order to provide additional time to obtain regulatory approval from the FRB. The merger received approval from both the New York State Department of Financial Services and the Connecticut Department of Banking in October 2021. Approval by the FRB is the only outstanding regulatory approval required to complete the merger.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	NOTE 28 – Selected Quarterly Financial Data (Unaudited) The following table presents People’s United’s quarterly financial data for 2021 and 2020: 2021 (1) 2020 (1) (dollars in millions, except First Second Third Fourth First Second Third Fourth Interest and dividend income $ 417.0 $ 406.3 $ 393.8 $ 384.2 $ 499.1 $ 457.6 $ 436.8 $ 421.5 Interest expense 31.1 25.4 23.5 22.2 103.1 52.0 45.4 38.7 Net interest income 385.9 380.9 370.3 362.0 396.0 405.6 391.4 382.8 Provision for credit losses (13.6) (40.8) 12.1 (6.0) 33.5 80.8 26.8 14.7 Net interest income after 399.5 421.7 358.2 368.0 362.5 324.8 364.6 368.1 Non-interest income 94.6 99.0 100.4 99.6 123.8 89.6 101.1 178.2 Non-interest expense 311.9 305.0 289.2 277.7 320.1 304.0 293.6 646.4 Income (loss) before income 182.2 215.7 169.4 189.9 166.2 110.4 172.1 (100.1) Income tax expense 37.7 44.9 29.7 40.0 35.8 20.5 27.5 45.2 Net income (loss) 144.5 170.8 139.7 149.9 130.4 89.9 144.6 (145.3) Preferred stock dividend 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 Net income (loss) available to $ 141.0 $ 167.3 $ 136.2 $ 146.4 $ 126.9 $ 86.4 $ 141.1 $ (148.8) Common Share Data: EPS: Basic $ 0.34 $ 0.40 $ 0.32 $ 0.35 $ 0.30 $ 0.21 $ 0.34 $ (0.36) Diluted 0.33 0.39 0.32 0.34 0.30 0.21 0.34 (0.35) Common dividends paid 75.7 77.3 77.4 77.4 77.3 75.5 75.7 75.6 Dividends paid per 0.1800 0.1825 0.1825 0.1825 0.1775 0.1800 0.1800 0.1800 Common dividend payout ratio 53.7 % 46.2 % 56.8 % 52.9 % 60.9 % 87.4 % 53.6 % (50.8) % Stock price: High $ 19.40 $ 19.62 $ 18.08 $ 19.05 $ 17.00 $ 13.99 $ 12.36 $ 13.58 Low 12.66 16.75 15.18 16.20 10.40 9.37 9.74 9.98 Weighted average common shares Basic 419.12 421.09 421.43 421.65 427.18 417.91 418.05 418.15 Diluted 422.58 425.08 424.77 425.45 429.77 420.15 420.29 420.39 (1) The sum of the quarterly amounts for certain line items may not equal the full-year amounts due to rounding.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Financial Statement Presentation	Basis of Financial Statement Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of People’s United and its subsidiaries. All significant intercompany transactions and balances are eliminated in consolidation. Certain reclassifications have been made to prior period amounts to conform to the current period presentation. In preparing the consolidated financial statements, management is required to make significant estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. Actual results could differ from management’s current estimates, as a result of changing conditions and future events. Several accounting estimates are particularly critical and are susceptible to significant near-term change, including the allowance for credit losses (“ACL”) and the recoverability of goodwill and other intangible assets. These accounting estimates, which are included in the discussion below, are reviewed with the Audit Committee of the Board of Directors. The Financial Accounting Standards Board (the “FASB”) issued changes to several accounting standards, some of which govern key aspects of the Company’s financial statements. Most notably, the FASB’s standard on accounting for credit losses (the “CECL standard”), removed from U.S. GAAP the existing “probable” threshold for recognizing credit losses and, instead, utilizes an “expected credit loss” measurement principle. The CECL standard, which was adopted by the Company on The judgments used by management in applying critical accounting policies may be affected by economic conditions, which may result in changes to future financial results. For example, subsequent evaluations of the loan portfolio, in light of the factors then prevailing, may result in significant changes in the ACL in future periods, and the inability to collect outstanding principal may result in increased loan losses.
Cash Equivalents	For purposes of the Consolidated Statements of Cash Flows, cash equivalents include highly-liquid instruments, such as: (i) interest-bearing deposits at the Federal Reserve Bank of New York (the “FRB-NY”); (ii) government-sponsored enterprise (“GSE”) debt securities with an original maturity of three months or less (determined as of the date of purchase); (iii) federal funds sold; (iv) commercial paper; and (v) money market mutual funds. These instruments are reported as short-term investments in the Consolidated Statements of Condition at cost or amortized cost, which approximates fair value. GSE debt securities classified as cash equivalents are held to maturity and carry the implicit backing of the U.S. government, but are not direct obligations of the U.S. government.
Securities	Securities Marketable debt securities (other than those reported as short-term investments) are classified as either trading debt securities, debt securities held-to-maturity or debt securities available-for-sale. Management determines the classification of a security at the time of its purchase and reevaluates such classification at each balance sheet date. Debt securities purchased for sale in the near term as well as those securities held by PSI (in accordance with the requirements for a broker-dealer) are classified as trading debt securities and reported at fair value with gains and losses reported in non-interest income. Debt securities for which People’s United has the intent and ability to hold to maturity are classified as held-to-maturity securities and reported at amortized cost. All other debt securities are classified as available-for-sale and reported at fair value with unrealized gains and losses reported on an after-tax basis in stockholders’ equity as a component of accumulated other comprehensive income (loss) (“AOCL”). Premiums (discounts) are amortized (accreted) to interest income for debt securities, using the interest method over the remaining period to contractual maturity, adjusted for the effect of actual prepayments in the case of mortgage-backed and collateralized mortgage obligation (“CMO”) securities. Security transactions are recorded on the trade date. Realized gains and losses are determined using the specific identification method and reported in non-interest income. Debt securities transferred from available-for-sale to held-to-maturity are recorded at fair value at the date of transfer. The unrealized pre-tax gain or loss resulting from the difference between fair value and amortized cost at the transfer date becomes part of the new amortized cost basis of the securities and remains in AOCL. Such unrealized gains or losses are amortized to interest income as an adjustment to yield over the remaining life of the securities, offset by the amortization (accretion) of the premium (discount) resulting from the transfer at fair value, with no effect to net income. In connection with the Company's adoption of the CECL standard on January 1, 2020, selected accounting policies related to securities were revised and/or certain accounting policy elections were implemented. These policies are described below. Allowance for Credit Losses – Available-for-Sale Securities For available-for sale securities in an unrealized loss position, management first assesses whether (i) the Company intends to sell, or (ii) it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either criteria are met, any previously recognized ACL (see below) is charged-off and the security's amortized cost is written down to fair value through income. If neither criteria are met, the security is evaluated to determine whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, management considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, an ACL is recorded for the credit loss, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that has not been recorded through an ACL is recognized in other comprehensive income. Adjustments to the ACL are reported as a component of credit loss expense. Available-for-sale securities are Allowance for Credit Losses – Held-to-Maturity Securities Management measures expected credit losses on held-to-maturity securities on a collective basis by major security type with each type sharing similar risk characteristics, and considers historical credit loss information that is adjusted for current conditions and reasonable and supportable forecasts. Held-to-maturity securities are charged-off against the ACL when deemed to be uncollectible and adjustments to the ACL are reported as a component of credit loss expense. The Company has made the accounting policy election to exclude accrued interest receivable on held-to-maturity securities from the estimate of credit losses. With regard to U.S. Treasury and residential mortgage-backed securities issued by the U.S. government, or agencies thereof, it is expected that the securities will not be settled at prices less than the amortized cost bases of the securities as such securities are backed by the full faith and credit of and/or guaranteed by the U.S. government. Accordingly, no ACL has been recorded for these securities. With regard to securities issued by corporations, states and/or political subdivisions and other held-to-maturity securities, management considers a number of factors, including: (i) issuer bond ratings; (ii) historical loss rates for given bond ratings; and (iii) whether issuers continue to make timely principal and interest payments under the contractual terms of the securities. For periods prior to January 1, 2020, management conducted periodic reviews and evaluation of the debt securities portfolio to determine if the decline in fair value of any security was deemed to be other-than-temporary. Other-than-temporary impairment losses were recognized on debt securities when: (i) People’s United had an intention to sell the security; (ii) it was more likely than not that People’s United would be required to sell the security prior to recovery; or (iii) People’s United did not expect to recover the entire amortized cost basis of the security. Other-than-temporary impairment losses on debt securities were reflected in earnings as realized losses to the extent the impairment is related to credit losses of the issuer. The amount of the impairment related to other factors was recognized in other comprehensive income. Both FRB-NY stock and Federal Home Loan Bank (“FHLB”) stock are non-marketable equity securities and are, therefore, reported at their respective costs, which equals par value (the amount at which shares have been redeemed in the past). These investments are periodically evaluated for impairment based on, among other things, the capital adequacy of the FRB-NY or the FHLB and their overall financial condition. Equity securities are reported at fair value with gains and losses reported in non-interest income.
Securities Resale and Securities Repurchase Agreements	Securities Resale and Securities Repurchase Agreements In securities resale agreements, a counterparty transfers securities to People’s United (as transferee) and People’s United agrees to resell the same securities to the counterparty at a fixed price in the future. In securities repurchase agreements,
Loans Held-for-Sale	Loans Held-for-Sale Loans held-for-sale are reported at the lower of cost or fair value in the aggregate with any adjustment for net unrealized losses reported in non-interest income. Management identifies and designates as loans held-for-sale certain newly-originated adjustable-rate and fixed-rate residential mortgage loans that meet secondary market requirements, as these loans are originated with the intent to sell. From time to time, management may also identify and designate certain loans previously
Loans	Loans As a result of adopting the CECL standard on January 1, 2020, the Company’s prior distinction between the originated loan portfolio and the acquired loan portfolio is no longer necessary. In addition, selected accounting policies related to loans were revised and/or certain accounting policy elections were implemented. These policies are described below. Basis of Accounting Loans are reported at amortized cost less the ACL. Interest on loans is accrued to income monthly based on outstanding principal balances. Loan origination fees and certain direct loan origination costs are deferred, and the net fee or cost is recognized in interest income as an adjustment of yield. Depending on the loan portfolio, amounts are amortized or accreted using the level yield method over either the actual life or the estimated average life of the loan. Allowance for Credit Losses The ACL on loans, calculated in accordance with the CECL standard, is deducted from the amortized cost basis of loans to present the net amount expected to be collected. The amount of the allowance represents management’s best estimate of current expected credit losses on loans considering available information, from both internal and external sources, deemed relevant to assessing collectability over the loans' contractual terms, adjusted for anticipated prepayments, as appropriate. Accrued interest on loans is excluded from the calculation of the ACL due to the Bank’s established non-accrual policy, which results in the reversal of uncollectible accrued interest on non-accrual loans against interest income in a timely manner Purchased Credit Deteriorated Loans In addition to originating loans, the Company may acquire loans through portfolio purchases or acquisitions of other companies. Purchased loans that have evidence of more than insignificant credit deterioration since origination are deemed purchased credit deteriorated (“PCD”) loans. In connection with its adoption of the CECL standard, the Company did not reassess whether previously recognized purchased credit impaired (“PCI”) loans accounted for under prior accounting guidance met the criteria of a PCD loan as of the date of adoption. PCD loans are initially recorded at fair value along with an ACL determined using the same methodology as originated loans. The sum of the loan's purchase price and ACL becomes its initial amortized cost basis. The difference between the initial amortized cost basis and the par value of the loan is a noncredit discount or premium, which is amortized into interest income over the life of the loan. Subsequent changes to the ACL are recorded through provision for credit losses. Collateral Dependent Loans Loans for which the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the operation or sale of the collateral are considered to be collateral dependent loans. Collateral can have a significant financial effect in mitigating exposure to credit risk and, where there is sufficient collateral, an allowance for expected credit losses is not recognized or is minimal. For collateral dependent commercial loans, the allowance for expected credit losses is individually assessed based on the fair value of the collateral. Various types of collateral are used, including real estate, inventory, equipment, accounts receivable, securities and cash, among others. For commercial real estate loans, collateral values are generally based on appraisals which are updated based on management judgment under the specific circumstances on a case-by-case basis. The collateral value for other financial assets is generally based on quoted market prices or broker quotes (in the case of securities) or appraisals. Commercial loan balances are charged-off at the time all or a portion of the balance is deemed uncollectible. Collateral dependent residential mortgage and home equity loans are carried at the lower of amortized cost or fair value of the collateral less costs to sell, with any excess in the carrying amount of the loan representing the related ACL. Collateral values are based on broker price opinions or appraisals. Loans Loans acquired in connection with business combinations are referred to as ‘acquired’ loans as a result of the manner in which they are accounted for (see further discussion under ‘Acquired Loans’ below). All other loans are referred to as ‘originated’ loans. Basis of Accounting Originated loans are reported at amortized cost less the allowance for loan losses. Interest on loans is accrued to income monthly based on outstanding principal balances. Loan origination fees and certain direct loan origination costs are deferred, and the net fee or cost is recognized in interest income as an adjustment of yield. Depending on the loan portfolio, amounts are amortized or accreted using the level yield method over either the actual life or the estimated average life of the loan. Non-Accrual Loans A loan is generally considered “non-performing” when it is placed on non-accrual status. A loan is generally placed on non-accrual status when it becomes 90 days past due as to interest or principal payments. Past due status is based on the contractual payment terms of the loan. A loan may be placed on non-accrual status before it reaches 90 days past due if such loan has been identified as presenting uncertainty with respect to the collectability of interest and principal. A loan past due All previously accrued but unpaid interest on non-accrual loans is reversed from interest income in the period in which the accrual of interest is discontinued. Interest payments received on non-accrual loans (including impaired loans) are generally applied as a reduction of principal if future collections are doubtful, although such interest payments may be recognized as income. A loan remains on non-accrual status until the factors that indicated doubtful collectability no longer exist or until a loan is determined to be uncollectible and is charged off against the allowance for loan losses. Impaired Loans A loan is considered impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impaired loans also include certain loans whose terms have been modified in such a way that they are considered TDRs. Loans are considered TDRs if the borrower is experiencing financial difficulty and is afforded a concession by People’s United, such as, but not limited to: (i) payment deferral; (ii) a reduction of the stated interest rate for the remaining contractual life of the loan; (iii) an extension of the loan’s original contractual term at a stated interest rate lower than the current market rate for a new loan with similar risk; (iv) capitalization of interest; or (v) forgiveness of principal or interest. TDRs may either be accruing or placed on non-accrual status (and reported as non-performing loans) depending upon the loan’s specific circumstances, including the nature and extent of the related modifications. TDRs on non-accrual status remain classified as such until the loan qualifies for return to accrual status. Loans qualify for return to accrual status once they have demonstrated performance with the restructured terms of the loan agreement for a minimum of six months in the case of a commercial loan or, in the case of a retail loan, when the loan is less than 90 days past due. Loans may continue to be reported as TDRs after they are returned to accrual status. In accordance with regulatory guidance, residential mortgage and home equity loans restructured in connection with the borrower’s bankruptcy and meeting certain criteria are also required to be classified as TDRs, included in non-performing loans and written down to the estimated collateral value, regardless of delinquency status. Acquired loans that are modified are not considered for TDR classification provided they are evaluated for impairment on a pool basis (see further discussion under ‘Acquired Loans’ below). Impairment is evaluated on a collective basis for pools of retail loans possessing similar risk and loss characteristics and on an individual basis for other loans. If a loan is deemed to be impaired, a specific valuation allowance is allocated, if necessary, so that the loan is reported (net of the allowance) at the present value of expected future cash flows discounted at the loan’s original effective interest rate or at the fair value of the collateral less cost to sell if repayment is expected solely from the collateral. Interest payments on impaired non-accrual loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectible. Acquired Loans Loans acquired in a business combination are initially recorded at fair value with no carryover of an acquired entity’s previously established allowance for loan losses. Fair value of the loans is determined using market participant assumptions in estimating the amount and timing of both principal and interest cash flows expected to be collected, as adjusted for an estimate of future credit losses and prepayments, and then applying a market-based discount rate to those cash flows. Acquired loans are evaluated upon acquisition and classified as either purchased performing or PCI. For purchased performing loans, any premium or discount, representing the difference between the fair value and the outstanding principal balance of the loans, is recognized (using the level yield method) as an adjustment to interest income over the remaining period to contractual maturity or until the loan is repaid in full or sold. Subsequent to the acquisition date, the method utilized to estimate the required allowance for loan losses for these loans is similar to that for originated loans. However, a provision for loan losses is only recorded when the required allowance for loan losses exceeds any remaining purchase discount at the loan level. PCI loans represent those acquired loans with specific evidence of deterioration in credit quality since origination and for which it is probable that, as of the acquisition date, all contractually required principal and interest payments will not be collected . Such loans are generally accounted for on a pool basis, with pools formed based on the loans’ common risk characteristics, such as loan collateral type and accrual status. Each pool is accounted for as a single asset with a single composite interest rate and an aggregate expectation of cash flows. Under the accounting model for PCI loans, the excess of cash flows expected to be collected over the carrying amount of the loans, referred to as the “accretable yield”, is accreted into interest income over the life of the loans in each pool using the level yield method. Accordingly, PCI loans are not subject to classification as non-accrual in the same manner as other loans. Rather, PCI loans are considered to be accruing loans because their interest income relates to the accretable yield recognized at the pool level and not to contractual interest payments at the loan level. The difference between contractually required principal and interest payments and the cash flows expected to be collected, referred to as the “nonaccretable difference”, includes estimates of both the impact of prepayments and future credit losses expected to be incurred over the life of the loans in each pool. As such, charge-offs on PCI loans are first applied to the nonaccretable difference and then to any allowance for loan losses recognized subsequent to acquisition. Subsequent to acquisition, actual cash collections are monitored relative to management’s expectations and revised cash flow forecasts are prepared, as warranted. These revised forecasts involve updates, as necessary, of the key assumptions and estimates used in the initial estimate of fair value. Generally speaking, expected cash flows are affected by: • Changes in the expected principal and interest payments over the estimated life — Updates to changes in expected cash flows are driven by the credit outlook and actions taken with borrowers. Changes in expected future cash flows resulting from loan modifications are included in the assessment of expected cash flows; • Changes in prepayment assumptions — Prepayments affect the estimated life of the loans which may change the amount of interest income, and possibly principal, expected to be collected; and • Changes in interest rate indices for variable rate loans — Expected future cash flows are based, as applicable, on the variable rates in effect at the time of the assessment of expected cash flows. A decrease in expected cash flows in subsequent periods may indicate that the loan pool is impaired, which would require the establishment of an allowance for loan losses by a charge to the provision for loan losses. An increase in expected cash flows in subsequent periods serves, first, to reduce any previously established allowance for loan losses by the increase in the present value of cash flows expected to be collected, and results in a recalculation of the amount of accretable yield for the loan pool. The adjustment of accretable yield due to an increase in expected cash flows is accounted for as a change in estimate. The additional cash flows expected to be collected are reclassified from the nonaccretable difference to the accretable yield, and the amount of periodic accretion is adjusted accordingly over the remaining life of the loans in the pool. PCI loans may be resolved either through receipt of payment (in full or in part) from the borrower, the sale of the loan to a third party or foreclosure of the collateral. In the event of a sale of the loan, a gain or loss on sale is recognized and reported within non-interest income based on the difference between the sales proceeds and the carrying amount of the loan. In other cases, individual loans are removed from the pool based on comparing the amount received from its resolution (fair value of the underlying collateral less costs to sell in the case of a foreclosure) with its outstanding balance. Any difference between these amounts is absorbed by the nonaccretable difference established for the entire pool. For loans resolved by payment in full, there is no adjustment of the nonaccretable difference since there is no difference between the amount received at resolution and the outstanding balance of the loan. In these cases, the remaining accretable yield balance is unaffected and any material change in remaining effective yield caused by the removal of the loan from the pool is addressed in connection with the subsequent cash flow re-assessment for the pool. PCI loans subject to modification are not removed from the pool even if those loans would otherwise be deemed TDRs as the pool, and not the individual loan, represents the unit of account. Allowance and Provision for Loan Losses Originated Portfolio The allowance for loan losses is established through provisions for loan losses charged to income. Losses on loans, including impaired loans, are charged to the allowance for loan losses when all or a portion of a loan is deemed to be uncollectible. Recoveries of loans previously charged off are credited to the allowance for loan losses when realized. People’s United maintains the allowance for loan losses at a level that is deemed to be appropriate to absorb probable losses inherent in the respective loan portfolios, based on a quarterly evaluation of a variety of factors. These factors include, but are not limited to: (i) People’s United’s historical loan loss experience and recent trends in that experience; (ii) risk ratings assigned by lending personnel to commercial real estate loans, commercial and industrial loans, and equipment financing loans, and the results of ongoing reviews of those ratings by People’s United’s independent loan review function; (iii) an evaluation of delinquent and non-performing loans and related collateral values; (iv) the probability of loss in view of geographic and industry concentrations and other portfolio risk characteristics; (v) the present financial condition of borrowers; and (vi) current economic conditions. The Company’s allowance for loan losses consists of three elements: (i) an allowance for commercial loans collectively evaluated for impairment; (ii) an allowance for retail loans collectively evaluated for impairment; and (iii) a specific allowance for loans individually evaluated for impairment, including loans classified as TDRs. Commercial Loans Collectively Evaluated for Impairment. The Company establishes a loan loss allowance for its commercial loans collectively evaluated for impairment using a methodology that incorporates (i) the probability of default for a given loan risk rating and (ii) historical loss-given-default data, both derived using appropriate look-back periods and loss emergence periods. In accordance with the Company’s loan risk rating system, each commercial loan is assigned a risk rating (using a nine-grade scale) by the originating loan officer, credit management, internal loan review or loan committee. Loans rated “One” represent those loans least likely to default while loans rated “Nine” represent a loss. The probability of loans defaulting for each risk rating, referred to as default factors, are estimated based on the historical pattern of loans migrating from one risk rating to another and to default status over time as well as the length of time that it takes losses to emerge. Estimated loan default factors, which are updated annually (or more frequently, if necessary), are multiplied by loan balances within each risk-rating category and again multiplied by a historical loss-given-default estimate for each loan type to determine an appropriate level of allowance by loan type. The historical loss-given-default estimates are also updated annually (or more frequently, if necessary) based on actual charge-off experience. This approach is applied to the commercial and industrial, commercial real estate and equipment financing components of the loan portfolio. In establishing the allowance for loan losses for commercial loans collectively evaluated for impairment, the Company also gives consideration to certain qualitative factors, including the macroeconomic environment and any potential imprecision inherent in its loan loss model that may result from having limited historical loan loss data which, in turn, may result in inaccurate probability of default and loss-given-default estimates. In this manner, historical portfolio experience, as described above, is not adjusted and the allowance for loan losses always includes a component attributable to qualitative factors, the degree of which may change from period to period as such qualitative factors indicate improving or worsening trends. The Company evaluates the qualitative factors on a quarterly basis in order to conclude that they continue to be appropriate. There were no significant changes in our approach to determining the qualitative component of the related allowance for loan losses during 2019. Retail Loans Collectively Evaluated for Impairment. Pools of retail loans possessing similar risk and loss characteristics are collectively evaluated for impairment. These loan pools include residential mortgage, home equity and other consumer loans that are not assigned individual loan risk ratings. Rather, the assessment of these portfolios, and the establishment of the related allowance for loan losses, is based upon a consideration of (i) historical portfolio loss experience over an appropriate look-back period and loss emergence period and (ii) certain qualitative factors. The qualitative component of the allowance for loan losses for retail loans collectively evaluated for impairment is intended to incorporate risks inherent in the portfolio, economic uncertainties, regulatory requirements and other subjective factors such as changes in underwriting standards. Accordingly, consideration is given to: (i) present and forecasted economic conditions, including unemployment rates; (ii) changes in industry trends, including the impact of new regulations, (iii) trends in property values; (iv) broader portfolio indicators, including delinquencies, non-performing loans, portfolio concentrations, and trends in the volume and terms of loans; and (v) portfolio-specific risk characteristics. Portfolio-specific risk characteristics considered include: (i) collateral values/loan-to-value (“LTV”) ratios (above and below 70%); (ii) borrower credit scores under the FICO scoring system (above and below a score of 680); and (iii) other relevant portfolio risk elements such as income verification at the time of underwriting (stated income vs. non-stated income) and the property’s intended use (owner-occupied, non-owner occupied, second home, etc.), the combination of which results in a loan being classified as either “High”, “Moderate” or “Low” risk. These risk classifications are reviewed quarterly to ensure that changes within the portfolio, as well as economic indicators and industry developments, have been appropriately considered in establishing the related allowance for loan losses. In establishing the allowance for loan losses for retail loans collectively evaluated for impairment, the amount reflecting the Company’s consideration of qualitative factors is added to the amount attributable to historical portfolio loss experience. In this manner, historical charge-off data (whether periods or amounts) is not adjusted and the allowance for loan losses always includes a component attributable to qualitative factors, the degree of which may change from period to period as such qualitative factors indicate improving or worsening trends. The Company evaluates the qualitative factors on a quarterly basis in order to conclude that they continue to be appropriate. There were no significant changes in our approach to determining the qualitative component of the related allowance for loan losses during 2019. Individually Impaired Loans. The allowance for loan losses also includes specific allowances for individually impaired loans. Generally, the Company’s impaired loans consist of (i) classified commercial loans in excess of $1 million that have been placed on non-accrual status and (ii) loans classified as TDRs. Individually impaired loans are measured based upon observable market prices; the present value of expected future cash flows discounted at the loan’s original effective interest rate; or, in the case of collateral dependent loans, fair value of the collateral (based on appraisals and other market information) less cost to sell. If the recorded investment in a loan exceeds the amount measured as described in the preceding sentence, a specific allowance for loan losses would be established as a component of the overall allowance for loan losses or, in the case of a collateral dependent loan, a charge-off would be recorded for the difference between the loan’s recorded investment and management’s estimate of the fair value of the collateral (less cost to sell). It would be rare for the Company to identify a loan that meets the criteria stated above and requires a specific allowance or a charge-off and not deem it impaired solely as a result of the existence of a guarantee. People’s United performs an analysis of its impaired loans, including collateral dependent impaired loans, on a quarterly basis. Individually impaired collateral dependent loans are measured based upon the appraised value of the underlying collateral and other market information. Generally, the Company’s policy is to obtain updated appraisals for commercial collateral dependent loans when the loan is downgraded to a risk rating of “substandard” or “doubtful”, and the most recent appraisal is more than 12 months old or a determination has been made that the property has experienced a significant decline in value. Appraisals are prepared by independent, licensed third-party appraisers and are subject to review by the Company’s internal commercial appraisal department or external appraisers contracted by the commercial appraisal department. The conclusions of the external appraisal review are reviewed by the Company’s Chief Commercial Appraiser prior to acceptance. The Company’s policy with respect to impaired loans secured by residential real estate is to receive updated estimates of property values upon the loan being classified as non-performing (typically upon becoming 90 days past due). In determining the allowance for loan losses, People’s United gives appropriate consideration to the age of appraisals through its regular evaluation of other relevant qualitative and quantitative information. Specifically, between scheduled appraisals, property values are monitored within the commercial portfolio by reference to current originations of collateral dependent loans and the related appraisals obtained during underwriting as well as by reference to recent trends in commercial property sales as published by leading industry sources. Property values are monitored within the residential mortgage and home equity portfolios by reference to available market indicators, including real estate price indices within the Company’s primary lending areas. In most situations where a guarantee exists, the guarantee arrangement is not a specific factor in the assessment of the related allowance for loan losses. However, the assessment of a guarantor’s credit strength is reflected in the Company’s internal loan risk ratings which, in turn, are an important factor in its allowance for loan loss methodology for loans within the commercial and industrial, and commercial real estate portfolios. People’s United did not change its methodologies with respect to determining the allowance for loan losses during 2019. As part of its ongoing assessment of the allowance for loan losses, People’s United regularly makes refinements to certain underlying assumptions used in its methodologies. However, such refinements did not have a material impact on the allowance for loan losses or the provision for loan losses as of or for the year ended December 31, 2019. Acquired Portfolio Acquired loans are evaluated upon acquisition and classified as either purchased performing or PCI, which represents those acquired loans with specific evidence of deterioration in credit quality since origination and for which it is probable that, as of the acquisition date, all contractually required principal and interest payments will not be collected. PCI loans are generally accounted for on a pool basis, with pools formed based on the loans’ common risk characteristics, such as loan collateral type and accrual status. Each pool is accounted for as a single asset with a single composite interest rate and an aggregate expectation of cash flows. For purchased performing loans, the required allowance for loan losses is determined in a manner similar to that for originated loans with a provision for loan losses only recorded when the required allowance for loan losses exceeds any remaining purchase discount at the loan level. For PCI loans, the difference between contractually required principal and interest payments at the acquisition date and the undiscounted cash flows expected to be collected at the acquisition date is referred to as the “nonaccretable difference”, which includes an estimate of future credit losses expected to be incurred over the life of the loans in each pool. A decrease in the expected cash flows in subsequent periods requires the establishment of an allowance for loan losses at that time.
Past Due and Non-accrual Loans	Past Due and Non-Accrual Loans Loans are considered past due if required principal and interest payments have not been received as of the date such payments were contractually due. A loan is generally considered “non-performing” when it is placed on non-accrual status. A loan is generally placed on non-accrual status when it becomes 90 days past due as to interest or principal payments. A loan may be placed on non-accrual status before it reaches 90 days past due if such loan has been identified as presenting uncertainty with respect to the collectability of interest and principal. A loan past due 90 days or more may remain on accruing status if such loan is both well secured and in the process of collection.
Troubled Debt Restructurings	Troubled Debt Restructurings Troubled debt restructurings (“TDRs”), which, beginning in 2020, also includes loans reasonably expected to become TDRs, represent loans for which the original contractual terms have been modified to provide for terms that are less than what the Company would be willing to accept for new loans with comparable risk because of deterioration in the borrower's financial condition. Such loan modifications are handled on a case-by-case basis and are negotiated to achieve mutually agreeable terms that maximize loan collectability and meet the borrower’s financial needs. Modifications may include changes to one or more terms of the loan, including, but not limited to: (i) payment deferral; (ii) a reduction in the stated interest rate for the remaining contractual life of the loan; (iii) an extension of the loan’s original contractual term at a stated interest rate lower than the current market rate for a new loan with similar risk; (iv) capitalization of interest; or (v) forgiveness of principal or interest. TDRs may either be accruing or placed on non-accrual status (and reported as non-accrual loans) depending upon the loan’s specific circumstances, including the nature and extent of the related modifications. TDRs on non-accrual status remain classified as such until the loan qualifies for return to accrual status. Loans qualify for return to accrual status once they have demonstrated performance with the restructured terms of the loan agreement for a minimum of six months in the case of a commercial loan or, in the case of a retail loan, when the loan is less than 90 days past due. Loans may continue to be reported as TDRs after they are returned to accrual status. In accordance with regulatory guidance, residential mortgage and home equity loans restructured in connection with the borrower’s bankruptcy and meeting certain criteria are also required to be classified as TDRs, included in non-accrual loans and written down to the estimated collateral value, regardless of delinquency status. The CARES Act and guidance issued by the Federal banking agencies provides that certain loan modifications to borrowers experiencing financial distress as a result of the economic impacts created by the COVID-19 pandemic are not required to be treated as TDRs under GAAP. As such, the Company suspended TDR accounting for COVID-19 related loan modifications meeting the loan modification criteria set forth under the CARES Act or as specified in the regulatory guidance. Further, loans granted payment deferrals related to COVID-19 are not required to be reported as past due or placed on
Allowance and Provision for Credit Losses	Allowance and Provision for Credit Losses The ACL is established through provisions for credit losses on loans charged to income. Losses on loans are charged to the ACL when all or a portion of a loan is deemed to be uncollectible. Recoveries of loans previously charged off are credited to the ACL when realized. On January 1, 2020, the Company adopted the CECL standard, which requires the measurement of expected credit losses for financial assets measured at amortized cost, including loans, and certain off-balance-sheet credit exposures. Allowance for Credit Losses – Loans Under the CECL standard, the Company determines the ACL on loans based upon a consideration of its historical portfolio loss experience, current borrower-specific risk characteristics, forecasts of future economic conditions and other relevant factors. The allowance is measured on a collective (pool) basis when similar risk characteristics exist. Loans that do not share common risk characteristics are evaluated on an individual basis and are excluded from the collective evaluation. The Company’s loan portfolio segments include Commercial and Retail and each of these segments comprises multiple loan classes, which are characterized by similarities in initial measurement, risk attributes, and the manner in which credit risk is monitored and assessed. The Commercial loan portfolio segment is comprised of the commercial real estate, commercial and industrial, equipment financing and mortgage warehouse/asset based lending (“MW/ABL”) loan classes. The Retail loan portfolio segment is comprised of the residential mortgage, home equity and other consumer loan classes. Common characteristics and risk profiles include the type/purpose of loan and historical/expected credit loss patterns. The Company periodically reassesses each pool to ensure the loans within the pool continue to share similar characteristics and risk profiles and to determine whether further segmentation is necessary. The ACL on loans represents management’s current estimate of lifetime expected credit losses inherent in the loan portfolio at the balance sheet date. As such, the estimate of expected credit losses is dependent upon portfolio size, composition and credit quality, as well as economic conditions and forecasts existing at that time. Expected future losses are estimated for the loan's entire contractual term adjusted for anticipated prepayments, as appropriate. The contractual term excludes expected extensions, renewals, and modifications unless (i) management has a reasonable expectation that a TDR will be executed with an individual borrower or (ii) such extension or renewal options are not unconditionally cancellable by the Company and, in such cases, the borrower is likely to meet applicable conditions and likely to request extension or renewal. Credit loss expense related to loans reflects the totality of actions taken on all loans for a particular period including any necessary increases or decreases in the allowance related to changes in credit loss expectations associated with specific loans or pools of loans. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged-off. While management utilizes its best judgment and information available, the ultimate appropriateness of the allowance is dependent upon a variety of factors beyond management's control, including the performance of the loan portfolio, changes in interest rates and the broader economy. The ACL on loans is comprised of three components: (i) quantitative (formulaic) reserves; (ii) qualitative (judgmental) reserves; and (iii) individual loan reserves. Quantitative Component. Management estimates the quantitative component by projecting (i) probability-of-default, representing the likelihood that a loan will stop performing/default (“PD”), (ii) loss-given-default, representing the expected loss rate for loans in default (“LGD”) and (iii) exposure-at-default (“EAD”), representing the estimated outstanding principal balance of the loans upon default, adjusted for anticipated prepayments, as appropriate, based on economic parameters for each month of a loan’s remaining contractual term. Expected credit losses for the quantitative component are calculated as the product of the PD, LGD and EAD. Historical credit experience provides the basis for the estimation of expected credit losses, with adjustments made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix, delinquency levels and terms, as well as for changes in the economic environment over a reasonable and supportable forecast period. The Company utilizes a two-year reasonable and supportable forecast period followed by a one-year period over which estimated losses revert, on a straight-line basis, to average historical loss experience, determined over the historical observation period, for the remaining life of the loan. PDs are estimated by analyzing internal data related to the historical performance of each loan pool over an economic cycle. PDs are adjusted to reflect the current impact of certain macroeconomic variables as well as their expected changes over the reasonable and supportable forecast period. The LGD is based on historical losses for each loan pool, adjusted to reflect the current impact of certain macroeconomic variables as well as their expected changes over a two-year forecast period. EAD is estimated using a linear regression model that estimates the average percentage of the loan balance that remains at the time of a default event. The macroeconomic variables utilized as inputs in the Company’s quantitative modeling process were selected primarily based on their relevance and correlation to historical credit losses. The Company’s quantitative models yield a measurement of expected credit losses reflective of average historical loss rates for periods subsequent to the reasonable and supportable forecast period by reverting such modeling inputs to their historical mean while also considering loan/borrower specific attributes. This same forecast/reversion period is used for all macroeconomic variables employed in all of the Company’s models. The measurement of expected credit losses is impacted by loan/borrower attributes and certain macroeconomic variables derived from an externally-sourced forward-looking economic scenario. Significant loan/borrower attributes utilized in the Company’s quantitative modeling include, among other things: (i) origination date; (ii) maturity date; (iii) payment type; (iv) collateral type and amount; (v) current risk rating (as applicable); (vi) current unpaid balance and commitment utilization rate; and (vii) payment status/delinquency history. Significant macroeconomic variables utilized in the Company’s quantitative modeling include, among other things: (i) U.S. Gross Domestic Product (“GDP”); (ii) selected market interest rates including U.S. Treasury rates, Prime rate, 30-year fixed mortgage rate, BBB corporate bond rate (spread), among others; Qualitative Component. The ACL on loans also includes qualitative considerations related to idiosyncratic risk factors, changes in current economic conditions that may not be reflected in quantitatively-derived results, weightings to economic scenarios based on an assessment of the economic outlook and other relevant factors. These qualitative adjustments may increase or decrease management's estimate of expected credit losses by a calculated percentage or amount based upon the estimated level of risk. The various risks that may be considered in making qualitative adjustments include, among other things, the impact of: The weighted estimate of expected credit losses under various economic scenarios is compared to the result of the Baseline scenario with the difference included as an element of the qualitative component. The Company recognizes an approach using three scenarios may be insufficient in certain economic environments. This may result in a change to the weighting assigned to the three scenarios or the inclusion of additional scenarios. For instance, as a result of a deterioration in U.S. economic conditions caused by the emergence, in March 2020, of the COVID-19 pandemic, and the corresponding increase in economic uncertainty, a fourth forward-looking economic scenario (the “Severe Downside” scenario) has also been considered for purposes of estimating expected credit losses since that time. While the Company’s loss estimation methodologies strive to reflect all relevant risk factors, uncertainty exists associated with, but not limited to, potential imprecision in the estimation process due to the inherent time lag of obtaining information and normal variations between estimates and actual outcomes, including with respect to forward-looking economic forecasts. The qualitative component is designed to adjust the ACL to reflect such risk factors. Individual Component. In some cases, management may determine that an individual loan exhibits unique risk characteristics which differentiate that loan from other loans within the pool. In such cases, the loans are evaluated for expected credit losses on an individual basis and excluded from the collective evaluation. Specific allocations of the ACL are determined by analyzing the borrower’s ability to repay amounts owed, collateral deficiencies, the relative risk of the loan and economic conditions affecting the borrower’s industry, among other things. For collateral dependent loans, expected credit losses are based on the fair value of the collateral at the measurement date, adjusted for estimated selling costs if satisfaction of the loan depends on the sale of the collateral. The Company reevaluates the fair value of collateral supporting collateral dependent loans on a quarterly basis. Allowance for Credit Losses – Off-Balance-Sheet Credit Exposures An ACL on off-balance-sheet credit exposures is reported in other liabilities in the Consolidated Statements of Condition. This liability represents an estimate of expected credit losses arising from off-balance-sheet exposures such as letters of credit, guarantees and unfunded commitments to extend credit. The process for measuring lifetime expected credit losses on such exposures is consistent with that for Commercial and Retail loans as discussed above (as applicable), but is subject to an additional estimate reflecting the likelihood that funding will occur. Adjustments to the liability are reported as a component of credit loss expense. No liability is recognized for off-balance-sheet credit exposures that are unconditionally cancellable. As noted above, People’s United updated its methodologies with respect to determining the ACL in accordance with adoption of the CECL standard on January 1, 2020. As part of its ongoing assessment of the ACL, People’s United regularly makes refinements to certain underlying assumptions used in its methodologies. However, such refinements did not have a material impact on the ACL or the provision for credit losses on loans as of or for the year ended December 31, 2021. While People’s United seeks to use the best available information to make these determinations, future adjustments to the ACL may be necessary based on changes in economic conditions, results of regulatory examinations, further information obtained regarding known problem loans, the identification of additional problem loans and other factors. Loan Charge-Offs The Company’s charge-off policies, which comply with standards established by banking regulators, are consistently applied from period to period. Charge-offs are recorded on a monthly basis. Partially charged-off loans continue to be evaluated on a monthly basis and additional charge-offs or loan loss provisions may be recorded on the remaining loan balance based on the same criteria. For unsecured consumer loans, charge-offs are generally recorded when the loan is deemed to be uncollectible or For commercial loans, a charge-off is recorded when the Company determines that it will not collect all amounts contractually due based on the fair value of the collateral less cost to sell. The decision whether to charge-off all or a portion of a loan rather than to record a specific or general loss allowance is based on an assessment of all available information that aids in determining the loan’s net realizable value. Typically, this involves consideration of both (i) the fair value of any collateral securing the loan, including whether the estimate of fair value has been derived from an appraisal or other market information and (ii) other factors affecting the likelihood of repayment, including the existence of guarantees and insurance. If the amount by which the Company’s recorded investment in the loan exceeds its net realizable value is deemed to be a confirmed loss, a charge-off is recorded. Otherwise, a specific or general reserve is established, as applicable. The comparatively low level of net loan charge-offs in recent years, in terms of absolute dollars and as a percentage of average total loans, may not be sustainable in the future.
Revenue from Contracts with Customers	Revenue from Contracts with Customers The Company earns revenue from a variety of sources. For revenue streams other than (i) net interest income and (ii) other revenues associated with financial assets and financial liabilities, including loans, leases, securities and derivatives, the Company generally applies the following steps with respect to revenue recognition: (i) identify the contract; (ii) identify the performance obligation; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation; and (v) recognize revenue when the performance obligation is satisfied. The Company’s contracts with customers are generally short-term in nature, typically due within one year or less, or cancellable by the Company or the customer upon a short notice period. Performance obligations for customer contracts are generally satisfied at a single point in time, typically when the transaction is complete, or over time. For performance obligations satisfied over time, the value of the products/services transferred to the customer are evaluated to determine when, and to what degree, performance obligations have been satisfied. Payments from customers are typically received, and revenue recognized, concurrent with the satisfaction of our performance obligations. In most cases, this occurs within a single financial reporting period. For payments received in advance of the satisfaction of our performance obligations, revenue recognition is deferred until such time the performance obligations have been satisfied. In cases where a payment has not been received despite satisfaction of our performance obligations, an estimate of the amount due is accrued in the period our performance obligations have been satisfied. For contracts with variable components, amounts for which collection is probable are accrued. The following summarizes the Company’s performance obligations for the more significant recurring revenue streams included in non-interest income: Service charges and fees on deposit accounts — Service charges and fees on deposit accounts consist of monthly account maintenance and other related fees (bank service charges) as well as cash management fees, which are earned for services related to payment processing, overdrafts, non-sufficient funds and other deposit account activity. The Company’s performance obligation for monthly service fees is generally satisfied, and the related revenue recognized, over the period in which the service is provided. Other deposit account related fees, including overdraft charges and cash management fees, are largely transactional-based, and therefore, the Company’s performance obligation is satisfied, and related revenue recognized, at a point in time. Payment for service charges on deposit accounts is primarily received immediately or in the following month through a direct charge to customers’ accounts. Card-based and other non-deposit fees — Card-based and other non-deposit fees are comprised, primarily, of debit and credit card income and ATM fees as well as certain commercial banking lending fees. Debit and credit card income is primarily comprised of interchange fees earned whenever the Company’s debit and credit cards are processed through card payment networks. ATM fees and commercial banking lending fees are largely transactional-based and, therefore, the Company’s performance obligation is satisfied, and related revenue recognized, at a point in time. Payment is typically received immediately or in the following month. Investment management fees — Investment management income is primarily comprised of fees earned from the management and administration of trusts and other customer assets. The Company’s performance obligation is generally satisfied over time and the resulting fees are recognized monthly, based upon the month-end market value of the assets under management and the applicable fee rate. Payment is generally received a few days after month end through a direct charge to customers’ accounts. The Company’s performance obligation for these transactional-based services is generally satisfied, and the related revenue recognized, at a point in time (i.e. as incurred). Payment is received shortly after services are rendered. Insurance commissions and fees — The Company’s insurance revenue, which represents commissions earned for performing broker- and agency-related services, has two distinct performance obligations. The first performance obligation is the selling of the policy as an agent for the carrier. This performance obligation is satisfied upon binding of the policy. The second performance obligation is the ongoing servicing of the policy that is satisfied over the life of the policy. For employee benefits, the payment is typically received monthly. For property and casualty, payments can vary but are typically received at, or in advance of, the policy period. Brokerage commissions and fees — Brokerage commissions and fees primarily relate to investment advisory and brokerage activities as well as the sale of mutual funds and annuities. The Company’s performance obligation for investment advisory services is generally satisfied, and the related revenue recognized, over the period in which the services are provided. Fees earned for brokerage activities, such as facilitating securities transactions, are generally recognized at the time of transaction execution. The performance obligation for mutual fund and annuity sales is satisfied upon sale of the underlying investment, and therefore, the related revenue is primarily recognized at the time of sale. Payment for these services is typically received immediately or in advance of the service. The revenue streams noted above represent approximately $276 million (or 70%), approximately $277 million (or 56%) and approximately $288 million (or 67%) of total non-interest income for the years ended December 31, 2021, 2020 and 2019, respectively. Of these amounts in the respective years, approximately 35%, 40% and 40% is allocated to the Commercial Banking operating segment, approximately 35%, 30% and 30% is allocated to the Retail Banking operating segment and approximately 30% in each year is allocated to the Wealth Management operating segment. The Company generally acts in a principal capacity, on its own behalf, in the majority of its contracts with customers.
Bank-Owned Life Insurance	Bank-Owned Life Insurance Bank-owned life insurance (“BOLI”) represents the cash surrender value of life insurance policies purchased on the lives of certain key executives and former key executives. BOLI funds are generally invested in separate accounts and are supported by a stable wrap agreement to fully insulate the underlying investments against changes in fair value. Increases in the cash surrender value of these policies and death benefits in excess of the related invested premiums are included in non-interest income in the Consolidated Statements of Income. The Company’s BOLI policies have been underwritten by highly-rated third party insurance carriers and the investments underlying these policies are deemed to be of low-to-moderate market risk.
Premises and Equipment	Premises and Equipment Premises and equipment are reported at cost less accumulated depreciation and amortization, except for land, which is reported at cost. Buildings, data processing and other equipment, computer software, furniture and fixtures are depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the remaining lease term, the estimated useful life of the improvements or 10 years. Capitalized software development costs are amortized on a straight-line basis over the estimated useful life of the software. Generally, the estimated useful lives are as follows: buildings — 40 years; data processing and other equipment — 3 to 5 years; computer software — 3 to 5 years; and furniture and fixtures — 10 years.
Goodwill and Other Acquisition-Related Intangible Assets	Goodwill and Other Acquisition-Related Intangible Assets An acquirer in a business combination is required, upon initially obtaining control of another entity, to recognize the assets, liabilities and any non-controlling interest in the acquiree at fair value as of the acquisition date. Contingent consideration, if any, is also recognized and measured at fair value on the date of acquisition. In addition, the accounting standards for business combinations require that: (i) acquisition-related transaction costs be expensed as incurred; (ii) specific requirements be met in order to accrue for a restructuring plan as part of the acquisition; (iii) certain pre-acquisition contingencies be recognized at fair value; and (iv) acquired loans be recorded at fair value as of the acquisition date without recognition of an ACL. Intangible assets are recognized in an amount equal to the excess of the consideration transferred over the fair value of the tangible net assets acquired. “Acquisition-related intangible assets” are separately identified, recognized and amortized, where appropriate, for assets such as trade names, certain contractual agreements and the estimated values of acquired core deposits and/or customer relationships. Mutual fund management contract intangibles recognized by People’s United are deemed to have indefinite useful lives and, accordingly, are not amortized. The remaining intangible asset is recognized as goodwill. Goodwill and indefinite-lived intangible assets are not amortized but, rather, are required to be reviewed for impairment at least annually, with impairment losses recognized as a charge to expense when they occur. Acquisition-related intangible assets other than goodwill and indefinite-lived intangible assets are amortized to expense over their estimated useful lives in a manner consistent with that in which the related benefits are expected to be realized, and are periodically reviewed by management to assess recoverability, with impairment losses recognized as a charge to expense if carrying amounts exceed fair values. The Company’s trade name intangibles are amortized on either (i) an accelerated basis over a period of approximately Goodwill is evaluated for impairment at the reporting unit level. For the purpose of the goodwill impairment evaluation, management has identified reporting units based upon the Company’s three operating segments: Commercial Banking; Retail Banking; and Wealth Management. The specific assets and liabilities assigned to the reporting units is based on whether such assets and liabilities will be employed in or relate to the operations of a particular reporting unit. Newly acquired goodwill is allocated to reporting units based on the degree to which a reporting unit is expected to benefit from the related acquisition. Entities have the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. The quantitative test is used to identify potential impairment, and involves comparing each reporting unit’s estimated fair value to its carrying amount, including goodwill. If the estimated fair value of a reporting unit exceeds its carrying amount, goodwill is not deemed to be impaired. Should the carrying amount of the reporting unit exceed its estimated fair value, an impairment loss shall be recognized in an amount equal to that excess, not to exceed the carrying amount of goodwill. The Company estimates the fair value of its reporting units by applying a weighting of values determined using (i) the discounted cash flow method of the income approach and (ii) the guideline public company method of the market approach. The income approach is based on significant assumptions and judgments, including internal forecasts and growth rates, as well as discount rates and terminal values that reflect management’s assessment of market participant views of the risks associated with the projected cash flows of the reporting units. The market approach is based on a comparison of certain financial metrics, including trading multiples and control premiums, derived from the market prices of stocks of companies that are actively traded and engaged in the same or similar businesses as the Company and the respective reporting unit. The derived multiples are then applied to the reporting unit’s financial metrics to produce an indication of value. Differences in the identification of reporting units or in the selection of valuation techniques and related assumptions could result in materially different evaluations of goodwill impairment.
Real Estate Owned	Real Estate Owned Real estate owned (“REO”) properties acquired through foreclosure or deed-in-lieu of foreclosure are recorded initially at the lower of cost or estimated fair value less costs to sell. Any write-down of the recorded investment in the related loan is charged to the ACL upon transfer to REO. Thereafter, an allowance for REO losses is established for any further declines in the property’s value. This allowance is increased by provisions charged to income and decreased by charge-offs for realized losses. Management’s periodic evaluation of the adequacy of the allowance is based on an analysis of individual properties, as well as a general assessment of current real estate market conditions.
Income Taxes	Income Taxes Deferred taxes are recognized for the estimated future tax effects attributable to “temporary differences” and tax loss carryforwards. Temporary differences are differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities. A deferred tax liability is recognized for all temporary differences that will result in future taxable income. A deferred tax asset is recognized for all temporary differences that will result in future tax deductions and for all tax loss carryforwards, subject to reduction of the asset by a valuation allowance in certain circumstances. This valuation allowance is recognized if, based on an analysis of available evidence, management determines that it is more likely than not that some portion or all of the deferred tax asset will not be realized. The valuation allowance is subject to ongoing adjustment based on changes in circumstances that affect management’s judgment about the realizability of the deferred tax asset. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to future taxable income. The effect on deferred tax assets and liabilities of a change in tax laws or rates is recognized in income tax expense in the period that includes the enactment date of the change. Individual tax positions taken or expected to be taken on a tax return must satisfy certain criteria in order for some or all of the related tax benefits to be recognized in the financial statements. Specifically, a recognition threshold of
Earnings Per Common Share	Earnings Per Common Share Basic earnings per common share (“EPS”) excludes dilution and is computed by dividing earnings attributable to common shareholders by the weighted average number of common shares outstanding for the year. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock (such as stock options and performance shares) were exercised or converted into additional common shares that would then share in the earnings of the entity. Diluted EPS is computed by dividing earnings attributable to common shareholders by the weighted average number of common shares outstanding for the year, plus an incremental number of common-equivalent shares computed using the treasury stock method. Unvested share-based payment awards, which include the right to receive non-forfeitable dividends or dividend equivalents, are considered to participate with common shareholders in undistributed earnings for purposes of computing EPS. Companies that have such participating securities, including People’s United, are required to calculate basic and diluted EPS using the two-class method. Restricted stock awards granted by People’s United are considered participating securities. Calculations of EPS under the two-class method (i) exclude from the numerator any dividends paid or owed on participating securities and any undistributed earnings considered to be attributable to participating securities and (ii) exclude from the denominator the dilutive impact of the participating securities.
Derivative Financial Instruments and Hedging Activities	Derivative Financial Instruments and Hedging Activities People’s United uses derivative financial instruments as components of its market risk management (principally to manage interest rate risk (“IRR”)). Certain other derivatives are entered into in connection with transactions with commercial customers. Derivatives are not used for speculative purposes. All derivatives are recognized as either assets or liabilities in the Consolidated Statements of Condition, reported at fair value and presented on a gross basis. Until a derivative is settled, a favorable change in fair value results in an unrealized gain that is recognized as an asset, while an unfavorable change in fair value results in an unrealized loss that is recognized as a liability. The Company generally applies hedge accounting to its derivatives used for market risk management purposes. Hedge accounting is permitted only if specific criteria are met, including a requirement that a highly effective relationship exist between the derivative instrument and the hedged item, both at inception of the hedge and on an ongoing basis. The hedge accounting method depends upon whether the derivative instrument is classified as a fair value hedge (i.e. hedging an exposure related to a recognized asset or liability, or a firm commitment) or a cash flow hedge (i.e. hedging an exposure related to the variability of future cash flows associated with a recognized asset or liability, or a forecasted transaction). Changes in the fair value of effective fair value hedges are recognized in current earnings (with the change in fair value of the hedged asset or liability also recorded in earnings). Changes in the fair value of effective cash flow hedges are recognized in other comprehensive income (loss) until earnings are affected by the variability in cash flows of the designated hedged item. Ineffective portions of hedge results are recognized in current earnings. Changes in the fair value of derivatives for which hedge accounting is not applied are recognized in current earnings. People’s United formally documents at inception all relationships between the derivative instruments and the hedged items, as well as its risk management objectives and strategies for undertaking the hedge transactions. This process includes linking all derivatives that are designated as hedges to specific assets and liabilities, or to specific firm commitments or forecasted transactions. People’s United also formally assesses, both at inception of the hedge and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in the fair values or cash flows of the hedged items. If it is determined that a derivative is not highly effective or has ceased to be a highly effective hedge, People’s United would discontinue hedge accounting prospectively. Gains or losses resulting from the termination of a derivative accounted for as a cash flow hedge remain in AOCL and are amortized to earnings over the remaining period of the former hedging relationship, provided the hedged item continues to be outstanding or it is probable the forecasted transaction will occur. People’s United uses the dollar offset method, regression analysis and scenario analysis to assess hedge effectiveness at inception and on an ongoing basis. Such methods are chosen based on the nature of the hedge strategy and are used consistently throughout the life of the hedging relationship. Certain derivative financial instruments are offered to commercial customers to assist them in meeting their financing and investing objectives and for their risk management purposes. These derivative financial instruments consist primarily of interest rate swaps and caps, but also include foreign exchange contracts. The interest rate and foreign exchange risks associated with customer interest rate swaps and caps and foreign exchange contracts are mitigated by entering into similar derivatives having essentially offsetting terms with institutional counterparties. Interest rate-lock commitments extended to borrowers relate to the origination of residential mortgage loans. To mitigate the IRR inherent in these commitments, People’s United enters into mandatory delivery and best efforts contracts to sell adjustable-rate and fixed-rate residential mortgage loans (servicing released). Forward commitments to sell and interest Changes in the fair value of derivatives for which hedge accounting is not applied are recognized in current earnings, including customer derivatives, interest-rate lock commitments and forward sale commitments.
Balance Sheet Offsetting	Balance Sheet Offsetting Assets and liabilities relating to certain financial instruments, including derivatives, may be eligible for offset in the Consolidated Statements of Condition and/or subject to enforceable master netting arrangements or similar agreements. People’s United’s derivative transactions with institutional counterparties are generally executed under International Swaps and Derivative Association (“ISDA”) master agreements, which include “right of set-off” provisions that provide for a single net settlement of all interest rate swap positions, as well as collateral, in the event of default on, or the termination of, any one contract. Nonetheless, the Company does not, except as discussed in Note 24, offset asset and liabilities under such arrangements in the Consolidated Statements of Condition. Collateral (generally in the form of marketable debt securities) pledged by counterparties in connection with derivative transactions is not reported in the Consolidated Statements of Condition unless the counterparty defaults. Collateral that has been pledged by People’s United to counterparties continues to be reported in the Consolidated Statements of Condition unless the Company defaults.
Fair Value Measurements	Fair Value Measurements Accounting standards related to fair value measurements define fair value, provide a framework for measuring fair value and establish related disclosure requirements. Broadly, fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Accordingly, an “exit price” approach is required in determining fair value. In support of this principle, a fair value hierarchy has been established that prioritizes the inputs used to measure fair value, requiring entities to maximize the use of market or observable inputs (as more reliable measures) and minimize the use of unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs generally require significant management judgment. The three levels within the fair value hierarchy are as follows: • Level 1 — Unadjusted quoted market prices for identical assets or liabilities in active markets that the entity has the ability to access at the measurement date (such as active exchange-traded equity securities or mutual funds and certain U.S. and government agency debt securities). • Level 2 — Observable inputs other than quoted prices included in Level 1, such as: ◦ quoted prices for similar assets or liabilities in active markets (such as U.S. agency and GSE issued ◦ quoted prices for identical or similar assets or liabilities in less active markets (such as certain U.S. and government agency debt securities, and corporate and municipal debt securities that trade infrequently); and ◦ other inputs that (i) are observable for substantially the full term of the asset or liability (e.g. interest rates, yield curves, prepayment speeds, default rates, etc.) or (ii) can be corroborated by observable market data (such as interest rate and currency derivatives and certain other securities). • Level 3 — Valuation techniques that require unobservable inputs that are supported by little or no market activity and are significant to the fair value measurement of the asset or liability (such as pricing models, discounted cash flow methodologies and similar techniques that typically reflect management’s own estimates of the assumptions a market participant would use in pricing the asset or liability). People’s United maintains policies and procedures to value assets and liabilities using the most relevant data available.
Stock-Based Compensation	Stock-Based Compensation People’s United’s stock-based compensation plans provide for awards of stock options, restricted stock and performance shares to directors, officers and employees. Costs resulting from the issuance of such share-based payment awards are required to be recognized in the financial statements based on the grant date fair value of the award. Stock-based compensation expense is recognized over the requisite service period, which is generally the vesting period.
New Accounting Standards	New Accounting Standards Reference Rate Reform In 2017, the United Kingdom’s Financial Conduct Authority announced that it will cease to compel its panel banks to submit London Interbank Offered Rate ( “LIBOR”) rates after December 31, 2021 as a result of the steadily decreasing number of transaction-based borrowing observations between banks in interbank funding markets. As a result, the 1-month, 3-month, In March 2020, the FASB issued a new standard providing temporary optional expedients and exceptions to existing In November 2020, the Federal banking agencies issued a statement encouraging banks that enter into new financial contracts prior to December 31, 2021 to utilize a reference rate other than LIBOR or include robust fallback language that specifies a clearly defined alternative reference rate after LIBOR's discontinuation. Separately, the agencies indicated that a bank may use any reference rate for its loans that the bank determines to be appropriate for its funding model and customer needs. People’s United began incorporating recent ISDA-derived LIBOR fallback language in new LIBOR-based interest rate swap transactions effective after January 25, 2021. In preparation for LIBOR cessation in June 2023, the Bank continues its remediation efforts, including necessary upgrades and enhancements to certain Bank systems, to ensure all LIBOR-based contracts contain appropriate fallback language specifying a clearly defined alternative reference rate once LIBOR is discontinued. Accordingly, at this time, People’s United cannot reasonably estimate the potential impact, if any, of reference rate reform on the Company’s Consolidated Financial Statements. In January 2021, the FASB issued clarifying guidance regarding the scope of the optional relief for reference rate reform contemplated in its March 2020 standard. This guidance permits entities to apply certain of the optional practical expedients and exceptions included in its March 2020 standard to the accounting for derivative contracts and hedging activities that may be affected by changes in interest rates used for discounting cash flows, computing variation margin settlements and calculating price alignment interest (the “discounting transition”). These optional practical expedients and exceptions may be applied to derivative instruments impacted by the discounting transition even if such instruments do not reference a rate that is expected to be discontinued. This guidance is effective immediately and an entity may elect to apply the amendments as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020 or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to January 7, 2021, up to the date that financial statements are available to be issued. Disclosure Requirements — Defined Benefit Plans In August 2018, the FASB issued targeted amendments that serve to make minor changes to the disclosure requirements for employers that sponsor defined benefit pension and/or other postretirement benefit plans. More specifically, the amendments (i) remove disclosures that are no longer considered cost beneficial, (ii) clarify the specific requirements of selected disclosures and (iii) add disclosure requirements identified as relevant. These amendments are effective for fiscal years ending after December 15, 2020 (January 1, 2021 for People’s United) and early adoption is permitted. The provisions set forth in this guidance, which the Company elected to early adopt in 2018, have been reflected in Note 19 (as applicable) and did not have a significant impact on the Company’s Consolidated Financial Statements. Simplifying the Accounting for Income Taxes In December 2019, the FASB amended its standards with respect to income taxes, simplifying the accounting in several areas, including intra-period tax allocation, deferred tax liabilities related to outside basis differences, and year-to-date losses in interim periods, among others. This amendment became effective on January 1, 2021 for People’s United. Currently, this guidance is not expected to have a significant impact on the Company’s Consolidated Financial Statements or related disclosures. Nonrefundable Fees and Other Costs In October 2020, the FASB issued guidance clarifying that an entity should amortize any premium on a callable debt security, if applicable, to the next call date, which is the first date when a call option as a specified price becomes exercisable. The guidance became effective on January 1, 2021 for People’s United and did not have a material impact on the Company’s Consolidated Financial Statements. Financial Statement Presentation In August 2021, the FASB amended its standards to incorporate recent SEC rule changes into the FASB Codification, including SEC Final Rule Releases No. 33-10786, Amendments to Financial Disclosures about Acquired and Disposed Businesses , and No. 33-10835, Update of Statistical Disclosures for Bank and Savings and Loan Registrants . These amendments are effective for fiscal years ending on or after December 15, 2021 (December 31, 2021 for People’s United) and did not have a material impact on the Company’s Consolidated Financial Statements.
Fair Value Measurements	Recurring Fair Value Measurements Trading Debt Securities, Equity Securities and Debt Securities Available-For-Sale When available, People’s United uses quoted market prices for identical securities received from an independent, nationally-recognized, third-party pricing service (as discussed further below) to determine the fair value of investment securities such as U.S. Treasury and agency securities and equity securities that are included in Level 1. When quoted market prices for identical securities are unavailable, People’s United uses prices provided by the independent pricing service based on recent trading activity and other observable information including, but not limited to, market interest rate curves, referenced credit spreads and estimated prepayment rates where applicable. These investments include certain U.S. and government agency debt securities, corporate and municipal debt securities and GSE mortgage-backed and CMO securities, all of which are included in Level 2. The Company’s debt securities available-for-sale are primarily comprised of GSE mortgage-backed securities. The fair value of these securities is based on prices obtained from the independent pricing service. The pricing service uses various techniques to determine pricing for the Company’s mortgage-backed securities, including option pricing and discounted cash flow analysis. The inputs include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, benchmark securities, bids, offers, reference data, monthly payment information and collateral performance. At both December 31, 2021 and 2020, the mortgage-backed securities available-for-sale portfolio was entirely comprised of GSE mortgage-backed and CMO securities with original final maturities ranging from 7 to 40 years. An active market exists for securities that are similar to the Company’s GSE mortgage-backed and CMO securities, making observable inputs readily available. Changes in the prices obtained from the pricing service are analyzed from month to month, taking into consideration changes in market conditions including changes in mortgage spreads, changes in U.S. Treasury security yields and changes in generic pricing of securities with similar duration. As a further point of validation, the Company generates its own month-end fair value estimate for all mortgage-backed securities, and state and municipal securities. While the Company has not adjusted the prices obtained from the independent pricing service, any notable differences between those prices and the Company’s estimates are subject to further analysis. This additional analysis may include a review of prices provided by other independent parties, a yield analysis, a review of average life changes using Bloomberg analytics and a review of historical pricing for the particular security. Based on management’s review of the prices provided by the pricing service, the fair values incorporate observable market inputs used by market participants at the measurement date and, as such, are classified as Level 2 securities. Other Assets As discussed in Note 19, certain unfunded nonqualified supplemental plans have been established to provide retirement benefits to certain senior officers. People’s United has funded two trusts to provide benefit payments to the extent such benefits are not paid directly by People’s United, the assets of which are included in other assets in the Consolidated Statements of Condition. When available, People’s United determines the fair value of the trust assets using quoted market prices for identical securities received from a third-party nationally recognized pricing service. Derivatives People’s United values its derivatives using internal models that are based on market or observable inputs, including interest rate curves and forward/spot prices for selected currencies. Derivative assets and liabilities included in Level 2 represent interest rate swaps and caps, foreign exchange contracts, risk participation agreements, forward commitments to sell residential mortgage loans and interest rate-lock commitments on residential mortgage loans. Non-Recurring Fair Value Measurements The valuation techniques and inputs used by People's United for those assets measured at fair value on a non-recurring basis, excluding goodwill, are described below. Loans Held-for-Sale Loans held-for-sale are recorded at the lower of amortized cost or fair value and are therefore measured at fair value on a Collateral Dependent Loans The Company’s approach to determining the fair value of collateral dependent loans is described in Note 1, “Summary of Significant Accounting Policies”. People’s United has estimated the fair values of these assets using Level 3 inputs, such as discounted cash flows based on inputs that are largely unobservable and, instead, reflect management’s own estimates of the assumptions a market participant would use in pricing such loans and/or the fair value of collateral based on independent third-party appraisals for collateral dependent loans. Such appraisals are based on the market and/or income approach to value and are subject to a discount REO and Repossessed Assets REO and repossessed assets are recorded at the lower of cost or fair value, less estimated selling costs, and are therefore measured at fair value on a non-recurring basis. People’s United has estimated the fair values of these assets using Level 3 inputs, such as independent third-party appraisals and price opinions. Such appraisals are based on the market and/or income approach to value and are subject to a discount (to reflect estimated cost to sell) that generally approximates 10%. Assets that are acquired through loan default are recorded as held-for-sale initially at the lower of the recorded investment in the loan or fair value (less estimated selling costs) upon the date of foreclosure/repossession. Subsequent to foreclosure/repossession, valuations are updated periodically and the carrying amounts of these assets may be reduced further. Mortgage Servicing Rights Mortgage servicing rights are evaluated for impairment based upon the fair value of the servicing rights as compared to their amortized cost. The fair value of mortgage servicing rights is based on a valuation model that calculates the present value of estimated net servicing income. This model incorporates certain assumptions that market participants would likely use in estimating future net servicing income, such as interest rates, prepayment speeds and the cost to service (including delinquency and foreclosure costs), all of which require a degree of management judgment. Adjustments are only recorded when the discounted cash flows derived from the valuation model are less than the carrying value of the asset. As such, mortgage servicing rights are subject to measurement at fair value on a non-recurring basis and are classified as Level 3 assets.
Segment Information	Public companies are required to report (i) certain financial and descriptive information about “reportable operating segments,” as defined, and (ii) certain enterprise-wide financial information about products and services, geographic areas and major customers. Operating segment information is reported using a “management approach” that is based on the way management organizes the segments for purposes of making operating decisions and assessing performance. People’s United’s operations are divided into three primary operating segments that represent its core businesses: Commercial Banking; Retail Banking; and Wealth Management. In addition, the Treasury area manages People’s United’s securities portfolio, short-term investments, brokered deposits, wholesale borrowings and the funding center. The Company’s operating segments have been aggregated into two reportable segments: Commercial Banking and Retail Banking. These reportable segments have been identified and organized based on the nature of the underlying products and services applicable to each segment, the type of customers to whom those products and services are offered and the distribution channel through which those products and services are made available. With respect to the Company’s traditional wealth management activities, this presentation results in the allocation of the Company’s insurance business (prior to its sale in November 2020) and certain trust activities to the Commercial Banking segment, and the allocation of the Company’s brokerage business and certain other trust activities to the Retail Banking segment. Commercial Banking consists principally of commercial real estate lending, middle market and business banking, equipment financing, and mortgage warehouse and asset-based lending. This segment also provides treasury management services, capital market capabilities and commercial deposit products. Commercial insurance services were previously provided through PUIA (see Note 2). Retail Banking includes, as its principal business lines, consumer lending (including residential mortgage and home equity lending) and consumer deposit gathering activities. This segment also includes brokerage, financial advisory services, investment management services and life insurance provided by PSI, investment advisory services and financial management and planning services provided by PUA and non-institutional trust services. People’s United’s segment disclosure is based on an internal profitability reporting system, which generates information by operating segment based on a series of management estimates and allocations regarding funds transfer pricing (“FTP”), the provision for credit losses on loans, non-interest expense and income taxes. These estimates and allocations, some of which are subjective in nature, are subject to periodic review and refinement. Any changes in estimates and allocations that may affect the reported results of any segment will not affect the consolidated financial position or results of operations of People’s United as a whole. FTP, which is used in the calculation of each operating segment’s net interest income, measures the value of funds used in and provided by an operating segment. The difference between the interest income on earning assets and the interest expense on funding liabilities, and the corresponding FTP charge for interest income or credit for interest expense, results in net spread income. For fixed-term assets and liabilities, the FTP rate is assigned at the time the asset or liability is originated by reference to the Company’s FTP yield curve, which is updated daily. For non-maturity-term assets and liabilities, the FTP rate is determined based upon the underlying characteristics, or behavior, of each particular product and results in the use of a historical rolling average FTP rate determined over a period that is most representative of the average life of the particular asset or liability. While the Company’s FTP methodology serves to remove IRR from the operating segments and better facilitate pricing decisions, thereby allowing management to assess the longer-term profitability of an operating segment more effectively, it may, in sustained periods of low and/or high interest rates, result in a measure of operating segment net interest income that is not reflective of current interest rates. A five-year rolling average net charge-off rate is used as the basis for the provision for credit losses on loans for the respective operating segment in order to present a level of portfolio credit cost that is representative of the Company’s historical experience, without presenting the potential volatility from year-to-year changes in credit conditions. While this method of allocation allows management to assess the longer-term profitability of an operating segment more effectively, it may result in a measure of an operating segment’s provision for credit losses on loans that does not reflect actual losses for the periods presented. The provision for credit losses for Treasury reflects the application of the CECL standard (see Note 4). People’s United allocates a majority of non-interest expenses to each operating segment using a full-absorption costing process (i.e. all expenses are fully-allocated to the segments). Direct and indirect costs are analyzed and pooled by process and assigned to the appropriate operating segment and corporate overhead costs are allocated to the operating segments. Income tax expense is allocated to each operating segment using a constant rate, based on an estimate of the consolidated effective income tax rate for the year. Average total assets and average total liabilities are presented for each reportable segment due to management’s reliance, in part, on such average balances for purposes of assessing segment performance. Average total assets of each reportable segment include allocated goodwill and intangible assets, both of which are reviewed for impairment at least annually. The "Other" category includes the residual financial impact from the allocation of revenues and expenses (including the provision for credit losses on loans) and certain revenues and expenses not attributable to a particular segment; assets and liabilities not attributable to a particular segment; reversal of the FTE adjustment since net interest income for each segment is presented on an FTE basis; and the FTP impact from excess capital. The "Other" category also includes certain gains totaling $3.9 million, $75.9 million and $10.9 million for the years ended December 31, 2021, 2020 and 2019, respectively (included in non-interest income), and certain charges totaling $47.8 million, $45.9 million and $65.6 million for the years ended December 31, 2021, 2020 and 2019, respectively (included in non-interest expense).
People's United Employee Pension and Other Postretirement Plans	People’s United Employee Pension and Other Postretirement Plans People’s United maintains a qualified noncontributory defined benefit pension plan (the “People’s Qualified Plan”) that covers substantially all full-time and part-time employees who (i) meet certain age and length of service requirements and (ii) were employed by the Bank prior to August 14, 2006. Benefits are based upon the employee’s years of credited service and either the average compensation for the last five years or the average compensation for the five New employees of the Bank starting on or after August 14, 2006 are not eligible to participate in the People’s Qualified Plan. Instead, the Bank makes contributions on behalf of these employees to a qualified defined contribution plan in an annual amount equal to 3% of the employee’s eligible compensation. Employee participation in this plan is restricted to employees who (i) are at least 18 years of age and (ii) worked at least 1000 hours in a year. Both full-time and part-time employees are eligible to participate as long as they meet these requirements. In July 2011, the Bank amended the People’s Qualified Plan to “freeze”, effective December 31, 2011, the accrual of pension benefits for People’s Qualified Plan participants. As such, participants will not earn any additional benefits after that date. Instead, effective January 1, 2012, the Bank began making contributions on behalf of these participants to a qualified defined contribution plan in an annual amount equal to 3% of the employee’s eligible compensation. In addition to the People’s Qualified Plan, People’s United maintained the qualified defined benefit pension plan that covered former United Financial employees who met certain eligibility requirements (the “United Financial Qualified Plan”). All benefits under this plan were frozen effective December 31, 2012. Effective March 31, 2021, the United Financial Qualified Plan was merged into the People’s Qualified Plan (together the “Qualified Plan”). People’s United also maintains (i) unfunded, nonqualified supplemental plans to provide retirement benefits to certain senior officers (the “People’s Supplemental Plans”) and (ii) an unfunded plan that provides retirees with optional medical, dental and life insurance benefits (the “People’s Postretirement Plan”). People’s United accrues the cost of these postretirement benefits over the employees’ years of service to the date of their eligibility for such benefit.
Employee Stock Ownership Plan	Employee Stock Ownership Plan In April 2007, People’s United established an ESOP. At that time, People’s United loaned the ESOP $216.8 million to purchase 10,453,575 shares of People’s United common stock in the open market. In order for the ESOP to repay the loan, People’s United expects to make annual cash contributions of approximately $18.8 million until 2036. Such cash contributions may be reduced by the cash dividends paid on unallocated ESOP shares, which totaled $4.1 million in 2021, $4.3 million in 2020 and $4.4 million in 2019. At December 31, 2021, the loan balance totaled $161.2 million. Employee participation in this plan is restricted to those employees who (i) are at least 18 years of age and (ii) worked at least 1000 hours within 12 months of their hire date or any plan year (January 1 to December 31) after their date of hire. Employees meeting the aforementioned eligibility criteria during the plan year must continue to be employed as of the last day of the plan year in order to receive an allocation of shares for that plan year. Shares of People’s United common stock are held by the ESOP and allocated to eligible participants annually based upon a percentage of each participant’s eligible compensation. Since the ESOP was established, a total of 5,226,788 shares of People’s United common stock have been allocated or committed to be released to participants’ accounts. At Compensation expense related to the ESOP is recognized at an amount equal to the number of common shares committed to be released by the ESOP for allocation to participants’ accounts multiplied by the average fair value of People’s United’s common stock during the reporting period. The difference between the fair value of the shares of People’s United’s common stock committed to be released and the cost of those common shares is recorded as a credit to additional paid-in capital (if fair value exceeds cost) or, to the extent that no such credits remain in additional paid-in capital, as a charge to retained earnings (if fair value is less than cost). Expense recognized for the ESOP totaled $5.9 million, $4.3 million and $5.7 million for the years ended December 31, 2021, 2020 and 2019, respectively.
Directors' Equity Compensation Plan	Directors’ Equity Compensation Plan The People's United Financial, Inc. Directors’ Equity Compensation Plan (the “Directors’ Plan”) provides for an annual award of shares of People's United common stock with a fair value of approximately $95,000 to each non-employee director immediately following each annual meeting of shareholders. Shares of People's United common stock issued pursuant to the Directors' Plan are subject to a one-year vesting period, with no post-vesting transfer restrictions. A total of 1,492,500 shares of People's United common stock are reserved for issuance under the Directors’ Plan. In 2021, 2020 and 2019, directors were granted a total of 44,262 shares, 75,267 shares and 58,340 shares, respectively, of People’s United common stock, with grant date fair values of $19.36 per share, $11.30 per share and $16.31 per share, respectively, at those dates. Expense totaling $0.8 million for the Directors’ Plan was recognized for the year ended December 31, 2021 and $0.9 million for both of the years ended December 31, 2020 and 2019. At December 31, 2021, a total of 214,452 shares remain available for issuance.

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	12 Months Ended
	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Cash and Short-Term Investments	Short-term investments consist of the following cash equivalents: As of December 31 (in millions) 2021 2020 Interest-bearing deposits at the FRB-NY $ 10,180.8 $ 3,598.9 Collateral posted for derivative instruments 73.4 151.9 Money market mutual funds 14.1 8.9 Other 0.5 6.3 Total short-term investments $ 10,268.8 $ 3,766.0

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Available-for-Sale and Held-to-Maturity Debt Securities Gains (Losses)	The amortized cost, ACL, gross unrealized gains and losses, and fair value of People’s United’s debt securities As of December 31, 2021 (in millions) Amortized ACL Gross Gross Fair Debt securities available-for-sale: U.S. Treasury and agency $ 632.7 $ — $ 4.0 $ — $ 636.7 GSE mortgage-backed and CMO securities 6,055.2 — 51.7 (99.6) 6,007.3 Total debt securities available-for-sale $ 6,687.9 $ — $ 55.7 $ (99.6) $ 6,644.0 Debt securities held-to-maturity: State and municipal $ 2,865.2 $ (0.1) $ 180.4 $ (3.0) $ 3,042.5 GSE mortgage-backed securities 893.5 — 15.6 — 909.1 Corporate 82.8 (1.4) 1.7 (0.1) 83.0 Other 1.5 — — — 1.5 Total debt securities held-to-maturity $ 3,843.0 $ (1.5) $ 197.7 $ (3.1) $ 4,036.1 As of December 31, 2020 (in millions) Amortized ACL Gross Gross Fair Debt securities available-for-sale: U.S. Treasury and agency $ 529.8 $ — $ 11.8 $ — $ 541.6 GSE mortgage-backed and CMO securities 4,274.7 — 110.9 (1.7) 4,383.9 Total debt securities available-for-sale $ 4,804.5 $ — $ 122.7 $ (1.7) $ 4,925.5 Debt securities held-to-maturity: State and municipal $ 2,824.3 $ (0.1) $ 236.0 $ — $ 3,060.2 GSE mortgage-backed securities 1,079.9 — 36.4 — 1,116.3 Corporate 89.7 (1.5) 1.0 (0.2) 89.0 Other 1.5 — — — 1.5 Total debt securities held-to-maturity $ 3,995.4 $ (1.6) $ 273.4 $ (0.2) $ 4,267.0
Summary of Changes in Allowance for Credit Loss on Debt Securities Held-to-Maturity	The following table summarizes changes in the ACL on debt securities held-to-maturity for the years ended December 31, 2021 and 2020: December 31, 2021 December 31, 2020 (in millions) Corporate State and municipal Total Corporate State and municipal Total Balance at beginning of period $ 1.5 $ 0.1 $ 1.6 $ — $ — $ — CECL transition adjustment — — — 1.8 0.1 1.9 Balance at beginning of period, adjusted 1.5 0.1 1.6 1.8 0.1 1.9 Provision charged (credited) to income (0.1) — (0.1) (0.3) — (0.3) Balance at end of period $ 1.4 $ 0.1 $ 1.5 $ 1.5 $ 0.1 $ 1.6
Summary of Credit Quality Indicators for Debt Securities Held-to-Maturity	The tables below indicate the credit profile of the Company's debt securities held-to-maturity at amortized cost: As of December 31, 2021 (in millions) Investment Grade Non-Investment Grade Total State and municipal $ 2,865.0 $ 0.2 $ 2,865.2 GSE mortgage-backed securities 893.5 — 893.5 Corporate 77.8 5.0 82.8 Other 1.5 — 1.5 Total $ 3,837.8 $ 5.2 $ 3,843.0 As of December 31, 2020 (in millions) Investment Grade Non-Investment Grade Total State and municipal $ 2,824.1 $ 0.2 $ 2,824.3 GSE mortgage-backed securities 1,079.9 — 1,079.9 Corporate 84.7 5.0 89.7 Other 1.5 — 1.5 Total $ 3,990.2 $ 5.2 $ 3,995.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	The following tables summarize those debt securities available-for-sale with unrealized losses classified as to the length of time the losses have existed and, for which no ACL has been recognized. Certain unrealized losses totaled less than Continuous Unrealized Loss Position Less Than 12 Months 12 Months Or Longer Total As of December 31, 2021 (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Debt securities available-for-sale: GSE mortgage-backed and CMO $ 2,978.3 $ (55.2) $ 1,120.9 $ (44.4) $ 4,099.2 $ (99.6) U.S. Treasury and agency 15.1 — — — 15.1 — Total $ 2,993.4 $ (55.2) $ 1,120.9 $ (44.4) $ 4,114.3 $ (99.6) Continuous Unrealized Loss Position Less Than 12 Months 12 Months Or Longer Total As of December 31, 2020 (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Debt securities available-for-sale: GSE mortgage-backed and CMO $ 225.5 $ (1.7) $ — $ — $ 225.5 $ (1.7) Total $ 225.5 $ (1.7) $ — $ — $ 225.5 $ (1.7)
Summary of Amortized Cost, Fair Value and Fully Taxable Equivalent ("FTE") Yield of Debt Securities Based on Remaining Period to Contractual Maturity	The following table is a summary of the amortized cost, fair value and fully taxable equivalent (“FTE”) yield of debt securities as of December 31, 2021, based on remaining period to contractual maturity. Information for GSE mortgage-backed and CMO securities is based on the final contractual maturity dates without considering repayments and prepayments. The FTE yields on state and municipal securities were computed using a 24.6% tax rate. Available-for-Sale Held-to-Maturity (dollars in millions) Amortized Fair FTE Amortized Fair FTE U.S. Treasury and agency: Within 1 year $ 372.3 $ 374.9 1.36 % $ — $ — — % After 1 but within 5 years 260.4 261.8 1.34 — — — Total 632.7 636.7 1.35 — — — GSE mortgage-backed and CMO Within 1 year 17.0 17.0 3.15 43.9 44.2 2.21 After 1 but within 5 years 76.8 80.4 3.11 705.7 716.6 2.45 After 5 but within 10 years 1,448.7 1,458.8 1.96 143.9 148.3 2.23 After 10 years 4,512.7 4,451.1 1.56 — — — Total 6,055.2 6,007.3 1.68 893.5 909.1 2.40 State and municipal: Within 1 year — — — 43.8 44.3 3.06 After 1 but within 5 years — — — 220.9 228.4 2.84 After 5 but within 10 years — — — 802.6 859.9 3.70 After 10 years — — — 1,797.9 1,909.9 3.45 Total — — — 2,865.2 3,042.5 3.47 Corporate: Within 1 year — — — 1.0 1.0 2.67 After 1 but within 5 years — — — 11.8 11.8 2.60 After 5 but within 10 years — — — 70.0 70.2 4.66 Total — — — 82.8 83.0 4.34 Other: After 1 but within 5 years — — — 1.5 1.5 1.75 Total — — — 1.5 1.5 1.75 Total: Within 1 year 389.3 391.9 1.44 88.7 89.5 2.63 After 1 but within 5 years 337.2 342.2 1.74 939.9 958.3 2.54 After 5 but within 10 years 1,448.7 1,458.8 1.96 1,016.5 1,078.4 3.56 After 10 years 4,512.7 4,451.1 1.56 1,797.9 1,909.9 3.45 Total $ 6,687.9 $ 6,644.0 1.65 % $ 3,843.0 $ 4,036.1 3.24 %
Schedule of Components of Net Security Losses	Years ended December 31 (in millions) 2021 2020 2019 Debt securities: Gains $ 2.1 $ — $ 0.5 Losses (2.1) — (0.4) Total debt securities — — 0.1 Trading debt securities: Gains (1) — — 0.1 Losses — — — Total trading debt securities — — 0.1 Net security gains $ — $ — $ 0.2 (1) Gains on trading debt securities totaled less than $0.1 million for the year ended December 31, 2020 (none in 2021).

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
Summary of Loans by Loan Portfolio Segment and Class	The following table summarizes People’s United’s loans by loan portfolio segment and class: As of December 31 (in millions) 2021 2020 Commercial: Commercial real estate (1) $ 11,936.7 $ 13,336.9 Commercial and industrial (1) 8,747.6 10,764.1 Equipment financing 5,143.1 4,930.0 MW/ABL 3,304.5 4,218.2 Total Commercial Portfolio 29,131.9 33,249.2 Retail: Residential mortgage: Adjustable-rate 4,064.3 5,517.3 Fixed-rate 2,940.0 3,001.6 Total residential mortgage 7,004.3 8,518.9 Home equity and other consumer: Home equity 1,635.9 1,997.2 Other consumer 79.2 104.2 Total home equity and other consumer 1,715.1 2,101.4 Total Retail Portfolio 8,719.4 10,620.3 Total loans $ 37,851.3 $ 43,869.5 (1) In the first quarter of 2021, the Company completed a portfolio review to ensure consistent classification of certain commercial loans across the Company's franchise and conformity to industry practice for such loans. As a result, approximately $350 million of loans secured by non-owner-occupied commercial properties were prospectively reclassified, in March 2021, from commercial and industrial loans to commercial real estate loans. Prior period balances were not restated to conform to the current presentation.
Summary of Aging Information by Class of Loan	The following tables summarize aging information by class of loan: Past Due As of December 31, 2021 (in millions) Current 30-89 90 Days Total Total Commercial: Commercial real estate $ 11,874.4 $ 6.7 $ 55.6 $ 62.3 $ 11,936.7 Commercial and industrial 8,717.5 13.4 16.7 30.1 8,747.6 Equipment financing 5,080.0 48.3 14.8 63.1 5,143.1 MW/ABL 3,304.5 — — — 3,304.5 Total 28,976.4 68.4 87.1 155.5 29,131.9 Retail: Residential mortgage 6,959.2 22.2 22.9 45.1 7,004.3 Home equity 1,620.8 8.0 7.1 15.1 1,635.9 Other consumer 78.7 0.4 0.1 0.5 79.2 Total 8,658.7 30.6 30.1 60.7 8,719.4 Total loans $ 37,635.1 $ 99.0 $ 117.2 $ 216.2 $ 37,851.3 Past Due As of December 31, 2020 (in millions) Current 30-89 90 Days Total Total Commercial: Commercial real estate $ 13,283.2 $ 27.3 $ 26.4 $ 53.7 $ 13,336.9 Commercial and industrial 10,694.9 17.3 51.9 69.2 10,764.1 Equipment financing 4,846.8 64.0 19.2 83.2 4,930.0 MW/ABL 4,218.2 — — — 4,218.2 Total 33,043.1 108.6 97.5 206.1 33,249.2 Retail: Residential mortgage 8,447.9 32.2 38.8 71.0 8,518.9 Home equity 1,977.3 8.4 11.5 19.9 1,997.2 Other consumer 103.4 0.7 0.1 0.8 104.2 Total 10,528.6 41.3 50.4 91.7 10,620.3 Total loans $ 43,571.7 $ 149.9 $ 147.9 $ 297.8 $ 43,869.5
Summarized Recorded Investments, by Class of Loan, in Originated Non-Performing Loans	The recorded investment in non-accrual loans, by class of loan and year of origination, is summarized as follows: Non-Accrual Loans As of December 31, 2021 (in millions) 2021 2020 2019 2018 2017 Prior Revolving Loans Revolving Loans Converted to Term Total Non-Accrual Loans With No ACL Commercial: Commercial real estate $ — $ — $ 10.9 $ 24.6 $ 4.9 $ 64.2 $ — $ 0.2 $ 104.8 $ 42.9 Commercial and industrial 0.3 0.1 5.3 1.0 4.5 16.5 2.7 12.7 43.1 11.3 Equipment financing 1.3 14.0 21.4 17.3 18.5 10.8 — — 83.3 2.2 MW/ABL — — — — — — — 0.8 0.8 — Total (1) 1.6 14.1 37.6 42.9 27.9 91.5 2.7 13.7 232.0 56.4 Retail: Residential mortgage — 0.2 1.8 4.3 1.3 34.2 — — 41.8 14.8 Home equity — 0.1 — 0.4 0.1 2.3 — 11.7 14.6 4.8 Other consumer — — 0.1 — — — — — 0.1 — Total (2) — 0.3 1.9 4.7 1.4 36.5 — 11.7 56.5 19.6 Total $ 1.6 $ 14.4 $ 39.5 $ 47.6 $ 29.3 $ 128.0 $ 2.7 $ 25.4 $ 288.5 $ 76.0 Non-Accrual Loans As of December 31, 2020 (in millions) 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Non-Accrual Loans With No ACL Commercial: Commercial real estate $ — $ 8.6 $ 9.7 $ 2.8 $ 1.9 $ 35.4 $ 0.2 $ 1.8 $ 60.4 $ 10.9 Commercial and industrial 0.2 3.1 2.3 16.2 13.4 17.5 15.5 7.2 75.4 27.8 Equipment financing 16.4 27.4 25.3 25.5 7.8 6.9 — — 109.3 0.6 MW/ABL — — — — — — — 1.0 1.0 — Total (1) 16.6 39.1 37.3 44.5 23.1 59.8 15.7 10.0 246.1 39.3 Retail: Residential mortgage — 2.9 3.9 1.8 2.6 51.1 — — 62.3 28.3 Home equity — — 0.4 0.1 0.6 2.8 — 16.6 20.5 7.9 Other consumer — 0.1 — 0.1 — — — — 0.2 — Total (2) — 3.0 4.3 2.0 3.2 53.9 — 16.6 83.0 36.2 Total $ 16.6 $ 42.1 $ 41.6 $ 46.5 $ 26.3 $ 113.7 $ 15.7 $ 26.6 $ 329.1 $ 75.5 As of December 31 (in millions) 2019 Commercial: Commercial real estate $ 53.8 Commercial and industrial 38.5 Equipment financing 47.7 Total (1) 140.0 Retail: Residential mortgage 63.3 Home equity 20.8 Other consumer — Total (2) 84.1 Total $ 224.1 (1) Reported net of government guarantees totaling $2.9 million, $2.5 million and $1.3 million at December 31, 2021, 2020 and 2019, respectively. These government guarantees relate, almost entirely, to guarantees provided by the SBA as well as selected other Federal agencies and represent the carrying value of the loans that are covered by such guarantees, the extent of which (i.e. full or partial) varies by loan. At December 31, 2021, 100% of the government guarantees relate to commercial and industrial loans. (2) Includes $12.3 million, $23.6 million and $17.0 million of loans in the process of foreclosure at December 31, 2021, 2020 and 2019, respectively.
Summary of Recorded Investments in TDRs by Class of Loan	The following tables summarize, by class of loan, the recorded investments in loans modified as TDRs during the years ended December 31, 2021 and 2020. For purposes of this disclosure, recorded investments represent amounts immediately prior to and subsequent to the restructuring. Year ended December 31, 2021 (dollars in millions) Number of Pre-Modification Post-Modification Commercial: Commercial real estate (1) 18 $ 74.1 $ 74.1 Commercial and industrial (2) 25 26.7 26.7 Equipment financing (3) 19 3.8 3.8 MW/ABL (4) 2 3.0 3.0 Total 64 107.6 107.6 Retail: Residential mortgage (5) 55 17.0 17.0 Home equity (6) 69 4.8 4.8 Other consumer — — — Total 124 21.8 21.8 Total 188 $ 129.4 $ 129.4 (1) Represents the following concessions: extension of term (10 contracts; recorded investment of $14.9 million); reduced payment and/or payment deferral (4 contracts; recorded investment of $37.8 million); or a combination of concessions (2) Represents the following concessions: extension of term (18 contracts; recorded investment of $16.8 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $4.6 million); or a combination of concessions (3) Represents the following concessions: extension of term (11 contracts; recorded investment of $0.9 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $1.5 million); or a combination of concessions (4) Represents the following concessions: extension of term (2 contracts; recorded investment of $3.0 million). (5) Represents the following concessions: loans restructured through bankruptcy (12 contracts; recorded investment of $1.8 million); extension of term (1 contract; recorded investment of $2.0 million); reduced payment and/or payment deferral (29 contracts; recorded investment of $8.6 million); or a combination of concessions (13 contracts; recorded investment of $4.6 million). (6) Represents the following concessions: loans restructured through bankruptcy (13 contracts; recorded investment of $1.4 million); extension of term (4 contracts; recorded investment of $0.2 million); reduced payment and/or payment deferral (13 contracts; recorded investment of $0.8 million); or a combination of concessions (39 contracts; recorded investment of $2.4 million). Year ended December 31, 2020 (dollars in millions) Number of Pre-Modification Post-Modification Commercial: Commercial real estate (1) 18 $ 16.7 $ 16.7 Commercial and industrial (2) 44 71.5 71.5 Equipment financing (3) 43 14.4 14.4 MW/ABL (4) 9 7.6 7.6 Total 114 110.2 110.2 Retail: Residential mortgage (5) 38 16.3 16.3 Home equity (6) 50 5.7 5.7 Other consumer — — — Total 88 22.0 22.0 Total 202 $ 132.2 $ 132.2 (1) Represents the following concessions: extension of term (13 contracts; recorded investment of $8.3 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $3.9 million); temporary rate reduction (1 contract; recorded investment of $0.4 million); or a combination of concessions (2 contracts; recorded investment of $4.1 million). (2) Represents the following concessions: extension of term (23 contracts; recorded investment of $30.0 million); reduced payment and/or payment deferral (10 contracts; recorded investment of $36.7 million); temporary rate reduction (3) Represents the following concessions: extension of term (21 contracts; recorded investment of $5.2 million); reduced payment and/or payment deferral (13 contracts; recorded investment of $3.4 million); or a combination of concessions (4) Represents the following concessions: extension of term (9 contracts; recorded investment of $7.6 million). (5) Represents the following concessions: loans restructured through bankruptcy (10 contracts; recorded investment of $2.4 million); reduced payment and/or payment deferral (12 contracts; recorded investment of $7.3 million); or a combination of concessions (16 contracts; recorded investment of $6.6 million). (6) Represents the following concessions: loans restructured through bankruptcy (19 contracts; recorded investment of $1.5 million); reduced payment and/or payment deferral (2 contracts; recorded investment of $0.2 million); or a combination of concessions (29 contracts; recorded investment of $4.0 million).
Summary of Recorded Investments in TDRs by Class of Loan, Subsequently Defaulted	The following is a summary, by class of loan, of information related to TDRs completed within the previous 12 months that subsequently defaulted during the years ended December 31, 2021 and 2020. For purposes of this disclosure, the previous 12 months is measured from January 1 of the respective prior year and a default represents a previously-modified loan that became past due 30 days or more during 2021 or 2020. 2021 2020 Years ended December 31 (dollars in millions) Number of Recorded Number of Recorded Commercial: Commercial real estate — $ — 2 $ 1.5 Commercial and industrial 1 1.2 8 4.7 Equipment financing 8 0.3 9 1.7 MW/ABL — — — — Total 9 1.5 19 7.9 Retail: Residential mortgage 6 2.8 2 0.1 Home equity 8 0.4 — — Other consumer — — — — Total 14 3.2 2 0.1 Total 23 $ 4.7 21 $ 8.0
Summary of Credit Quality Indicators by Class of Loan	The following tables present Commercial loan risk ratings, by class of loan and year of origination: As of December 31, 2021 (in millions) 2021 2020 2019 2018 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial real Pass $ 508.3 $ 916.4 $ 1,701.0 $ 1,177.7 $ 968.2 $ 4,796.2 $ 136.1 $ 32.9 $ 10,236.8 Special Mention 18.4 73.8 124.1 129.7 118.4 342.7 — 0.4 807.5 Substandard 3.3 11.3 112.5 149.7 106.6 506.2 1.5 0.2 891.3 Doubtful — — — 0.1 — 1.0 — — 1.1 Total $ 530.0 $ 1,001.5 $ 1,937.6 $ 1,457.2 $ 1,193.2 $ 5,646.1 $ 137.6 $ 33.5 $ 11,936.7 Commercial and Pass $ 1,646.7 $ 656.3 $ 834.3 $ 538.7 $ 445.9 $ 1,517.6 $ 2,475.4 $ 47.0 $ 8,161.9 Special Mention 2.2 2.9 19.3 10.9 41.5 81.6 24.7 8.4 191.5 Substandard 11.0 17.5 40.7 30.5 85.7 134.5 54.6 18.9 393.4 Doubtful — — 0.3 — — 0.5 — — 0.8 Total $ 1,659.9 $ 676.7 $ 894.6 $ 580.1 $ 573.1 $ 1,734.2 $ 2,554.7 $ 74.3 $ 8,747.6 Equipment financing: Pass $ 2,005.1 $ 1,151.2 $ 847.7 $ 390.6 $ 157.7 $ 78.5 $ — $ — $ 4,630.8 Special Mention 27.5 8.4 14.4 5.9 8.0 2.5 — — 66.7 Substandard 150.6 110.7 94.4 48.4 27.1 14.4 — — 445.6 Doubtful — — — — — — — — — Total $ 2,183.2 $ 1,270.3 $ 956.5 $ 444.9 $ 192.8 $ 95.4 $ — $ — $ 5,143.1 MW/ABL: Pass $ 44.7 $ 13.8 $ 15.0 $ 10.2 $ 3.1 $ 25.7 $ 3,147.8 $ — $ 3,260.3 Special Mention — — — — — — 12.6 — 12.6 Substandard — — — — — — 30.8 0.8 31.6 Doubtful — — — — — — — — — Total $ 44.7 $ 13.8 $ 15.0 $ 10.2 $ 3.1 $ 25.7 $ 3,191.2 $ 0.8 $ 3,304.5 As of December 31, 2020 (in millions) 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial real Pass $ 848.5 $ 1,743.2 $ 1,490.4 $ 1,397.8 $ 1,274.2 $ 5,039.3 $ 165.8 $ 19.7 $ 11,978.9 Special Mention 28.5 72.9 225.6 131.2 58.9 362.7 0.5 — 880.3 Substandard 12.0 26.7 63.3 51.9 63.2 252.7 2.8 4.2 476.8 Doubtful — — — — — 0.9 — — 0.9 Total $ 889.0 $ 1,842.8 $ 1,779.3 $ 1,580.9 $ 1,396.3 $ 5,655.6 $ 169.1 $ 23.9 $ 13,336.9 Commercial and Pass $ 2,952.8 $ 1,236.9 $ 821.9 $ 527.1 $ 487.2 $ 1,588.5 $ 1,949.1 $ 77.4 $ 9,640.9 Special Mention 113.9 41.7 46.4 120.3 57.1 122.1 80.8 6.3 588.6 Substandard 27.0 86.3 84.2 47.6 29.8 141.2 97.7 18.4 532.2 Doubtful — — — — 0.8 1.5 — 0.1 2.4 Total $ 3,093.7 $ 1,364.9 $ 952.5 $ 695.0 $ 574.9 $ 1,853.3 $ 2,127.6 $ 102.2 $ 10,764.1 Equipment financing: Pass $ 1,703.3 $ 1,358.7 $ 727.2 $ 362.1 $ 155.5 $ 67.1 $ — $ — $ 4,373.9 Special Mention 20.5 27.5 16.7 7.3 4.2 1.5 — — 77.7 Substandard 169.9 137.5 87.7 49.8 17.9 15.6 — — 478.4 Doubtful — — — — — — — — — Total $ 1,893.7 $ 1,523.7 $ 831.6 $ 419.2 $ 177.6 $ 84.2 $ — $ — $ 4,930.0 MW/ABL: Pass $ 99.4 $ 18.6 $ 18.3 $ 8.8 $ 14.1 $ 19.6 $ 3,994.3 $ — $ 4,173.1 Special Mention — 6.9 — — — — 20.5 — 27.4 Substandard — 1.7 — — — — 15.0 1.0 17.7 Doubtful — — — — — — — — — Total $ 99.4 $ 27.2 $ 18.3 $ 8.8 $ 14.1 $ 19.6 $ 4,029.8 $ 1.0 $ 4,218.2 The following tables present Retail loan risk classifications, by class of loan and year of origination: As of December 31, 2021 (in millions) 2021 2020 2019 2018 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Residential mortgage: Low Risk $ 753.4 $ 643.0 $ 277.0 $ 208.8 $ 321.4 $ 1,922.9 $ — $ — $ 4,126.5 Moderate Risk 567.1 602.8 243.7 215.6 253.3 463.1 — — 2,345.6 High Risk 62.0 53.5 36.8 56.3 73.3 250.3 — — 532.2 Total $ 1,382.5 $ 1,299.3 $ 557.5 $ 480.7 $ 648.0 $ 2,636.3 $ — $ — $ 7,004.3 Home equity: Low Risk $ 2.4 $ 2.4 $ 8.2 $ 24.2 $ 22.7 $ 29.2 $ 538.1 $ 44.4 $ 671.6 Moderate Risk 0.7 0.8 4.1 12.0 11.6 15.5 416.4 43.3 504.4 High Risk 0.4 0.6 9.4 8.9 5.4 13.6 308.4 113.2 459.9 Total $ 3.5 $ 3.8 $ 21.7 $ 45.1 $ 39.7 $ 58.3 $ 1,262.9 $ 200.9 $ 1,635.9 Other consumer: Low Risk $ 1.2 $ 0.5 $ 1.4 $ 1.3 $ 0.8 $ 2.6 $ 18.0 $ 1.2 $ 27.0 Moderate Risk — — — — — — 4.0 0.1 4.1 High Risk 4.7 2.4 11.8 7.0 0.7 5.1 15.5 0.9 48.1 Total $ 5.9 $ 2.9 $ 13.2 $ 8.3 $ 1.5 $ 7.7 $ 37.5 $ 2.2 $ 79.2 As of December 31, 2020 (in millions) 2020 2019 2018 2017 2016 Prior Revolving Loans Revolving Loans Converted to Term Total Residential mortgage: Low Risk $ 609.5 $ 349.1 $ 338.3 $ 504.0 $ 1,004.6 $ 1,793.8 $ — $ — $ 4,599.3 Moderate Risk 752.5 456.8 443.9 517.5 520.2 519.8 — — 3,210.7 High Risk 81.2 60.4 95.0 109.6 86.6 276.1 — — 708.9 Total $ 1,443.2 $ 866.3 $ 877.2 $ 1,131.1 $ 1,611.4 $ 2,589.7 $ — $ — $ 8,518.9 Home equity: Low Risk $ 1.9 $ 7.4 $ 21.1 $ 24.6 $ 10.7 $ 25.8 $ 580.0 $ 42.9 $ 714.4 Moderate Risk 0.6 3.7 9.2 12.2 6.6 13.4 520.0 45.3 611.0 High Risk 2.8 21.8 38.1 22.0 7.5 18.8 415.7 145.1 671.8 Total $ 5.3 $ 32.9 $ 68.4 $ 58.8 $ 24.8 $ 58.0 $ 1,515.7 $ 233.3 $ 1,997.2 Other consumer: Low Risk $ 0.9 $ 1.7 $ 1.7 $ 0.9 $ 0.4 $ 2.7 $ 11.4 $ 0.1 $ 19.8 Moderate Risk — — — — — 0.1 4.8 0.1 5.0 High Risk 5.5 27.3 17.9 2.3 1.0 8.5 16.8 0.1 79.4 Total $ 6.4 $ 29.0 $ 19.6 $ 3.2 $ 1.4 $ 11.3 $ 33.0 $ 0.3 $ 104.2 The following table is a summary of revolving loans that converted to term during the years ended December 31, 2021 and 2020: Years ended December 31 (in millions) 2021 2020 Commercial: Commercial real estate $ 15.3 $ 1.4 Commercial and industrial 25.1 53.3 Equipment financing — — MW/ABL — — Total 40.4 54.7 Retail: Residential mortgage — — Home equity 39.3 37.1 Other consumer 1.2 0.1 Total 40.5 37.2 Total $ 80.9 $ 91.9

Allowance For Credit Losses (Ta

Allowance For Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2021
Allowance for Credit Loss [Abstract]
Summary, by Loan Portfolio Segment, of Activity in Allowance for Loan Losses	The following table presents a summary, by loan portfolio segment, of activity in the ACL for the years ended December 31, 2021, 2020 and 2019: 2021 2020 2019 Years ended December 31 Commercial Retail Total Commercial Retail Total Commercial Retail Total Balance at beginning $ 303.6 $ 121.5 $ 425.1 $ 217.9 $ 28.7 $ 246.6 $ 209.5 $ 30.9 $ 240.4 CECL transition adjustment — — — (17.3) 89.5 72.2 — — — Balance at beginning 303.6 121.5 425.1 200.6 118.2 318.8 209.5 30.9 240.4 Charge-offs (48.3) (3.1) (51.4) (52.4) (6.5) (58.9) (27.5) (4.0) (31.5) Recoveries 12.8 5.3 18.1 6.4 2.7 9.1 6.3 3.1 9.4 Net loan (35.5) 2.2 (33.3) (46.0) (3.8) (49.8) (21.2) (0.9) (22.1) Provision for credit (66.5) 18.3 (48.2) 149.0 7.1 156.1 29.6 (1.3) 28.3 Balance at end $ 201.6 $ 142.0 $ 343.6 $ 303.6 $ 121.5 $ 425.1 $ 217.9 $ 28.7 $ 246.6
Summary of Changes in Allowance for Credit Losses on Off-Balance Sheet Credit Exposures	The following table summarizes changes in the ACL on off-balance-sheet credit exposures for the years ended December 31, 2021, 2020 and 2019: Years ended December 31 (in millions) 2021 2020 2019 Balance at beginning of period $ 26.9 $ 5.6 $ 2.7 CECL transition adjustment — 14.5 — Balance at beginning of period, adjusted 26.9 20.1 2.7 Provision charged (credited) to income 1.5 6.8 2.9 Balance at end of period $ 28.4 $ 26.9 $ 5.6

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Composition of Total Net Investment in Lease Financing Receivables	The composition of the Company’s total net investment in lease financing receivables included within equipment financing loans in the Consolidated Statements of Condition was as follows: As of December 31 (in millions) 2021 2020 Lease payments receivable $ 1,368.3 $ 1,418.4 Estimated residual value of leased assets 130.1 132.7 Gross investment in lease financing receivables 1,498.4 1,551.1 Plus: Deferred origination costs 10.2 11.6 Less: Unearned income (140.4) (150.7) Total net investment in lease financing receivables $ 1,368.2 $ 1,412.0
Contractual Maturities of Lease Financing Receivables	The contractual maturities of the Company's lease financing receivables were as follows: (in millions) December 31, 2021 2022 $ 532.9 2023 402.6 2024 292.0 2025 172.3 2026 83.0 Later years 15.6 Total $ 1,498.4
Summary of Lease Income	The following table summarizes People's United's total lease income for the years ended December 31, 2021, 2020 and 2019: Years ended December 31 (in millions) 2021 2020 2019 Lease financing receivables $ 66.3 $ 69.0 $ 66.7 Operating leases 44.7 49.7 50.8 Total lease income $ 111.0 $ 118.7 $ 117.5
Lease Costs	The following tables provide the components of lease cost and supplemental information: Years ended December 31 (in millions) 2021 2020 2019 Operating lease cost $ 63.0 $ 65.1 $ 61.6 Variable lease cost 9.8 10.0 8.6 Finance lease cost 0.3 0.3 0.1 Sublease income (2.2) (1.9) (1.4) Net lease cost $ 70.9 $ 73.5 $ 68.9
Lease Right-of-use Assets and Liabilities	As of December 31 (dollars in millions) 2021 2020 Lease ROU assets: Operating lease $ 210.6 $ 234.9 Finance lease 2.1 2.3 Lease liabilities: Operating lease 242.0 270.4 Finance lease 4.5 4.9 Weighted-average discount rate: Operating leases 2.86 % 3.08 % Finance leases 2.59 2.59 Weighted-average remaining lease term (in years): Operating leases 7.2 7.6 Finance leases 10.3 11.2 Years ended December 31 (dollars in millions) 2021 2020 2019 Cash payments included in the measurement of lease liabilities: Reported in operating cash from operating leases $ 68.6 $ 66.6 $ 61.7 Reported in financing cash from finance leases 0.1 0.1 0.1 ROU assets obtained in exchange for lessee: Operating lease liabilities 31.4 22.8 89.1 Finance lease liabilities — — 2.6
Schedule of Contractual Maturities of Lease Liabilities	The contractual maturities of the Company's lease liabilities as of December 31, 2021 were as follows: (in millions) Operating Leases Finance Leases 2022 $ 55.6 $ 0.5 2023 44.2 0.5 2024 38.8 0.5 2025 34.7 0.5 2026 24.5 0.5 Later years 74.1 2.6 Total lease payments 271.9 5.1 Less: Interest (29.9) (0.6) Total lease liabilities $ 242.0 $ 4.5

Goodwill and Other Acquisitio_2

Goodwill and Other Acquisition-Related Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	Changes in the carrying amount of People’s United’s goodwill are summarized as follows: Operating Segment (in millions) Commercial Retail Wealth Total Balance at December 31, 2019 $ 1,966.1 $ 1,010.9 $ 88.5 $ 3,065.5 Sale of PUIA (1) — — (31.7) (31.7) Goodwill impairment — (353.0) — (353.0) Balance at December 31, 2020 1,966.1 657.9 56.8 2,680.8 Balance at December 31, 2021 $ 1,966.1 $ 657.9 $ 56.8 $ 2,680.8 (1) See Note 2.
Other Acquisition-Related Intangible	The following is a summary of People’s United’s other acquisition-related intangible assets: 2021 2020 As of December 31 (in millions) Gross Accumulated Carrying Gross Accumulated Carrying Core deposit intangible $ 303.9 $ 230.9 $ 73.0 $ 303.9 $ 206.3 $ 97.6 Trade name intangible 123.9 85.5 38.4 123.9 79.6 44.3 Client relationships 24.4 10.5 13.9 24.4 8.4 16.0 Trust relationships 42.7 40.2 2.5 42.7 37.6 5.1 Insurance relationships 38.1 38.1 — 38.1 38.1 — Favorable lease agreements 2.9 2.9 — 2.9 0.9 2.0 Non-compete agreements 0.6 0.6 — 0.6 0.5 0.1 Total other acquisition-related $ 536.5 $ 408.7 $ 127.8 $ 536.5 $ 371.4 $ 165.1

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Components of Premises and Equipment	The components of premises and equipment are summarized below: As of December 31 (in millions) 2021 2020 Land $ 48.0 $ 51.1 Buildings 303.5 313.6 Leasehold improvements 166.5 169.6 Furniture and equipment 280.7 277.3 Total 798.7 811.6 Less: Accumulated depreciation and amortization 556.9 534.9 Total premises and equipment, net $ 241.8 $ 276.7

Other Assets and Other Liabil_2

Other Assets and Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Other Assets And Other Liabilities [Abstract]
Components of Other Assets	The components of other assets are as follows: As of December 31 (in millions) 2021 2020 Affordable housing investments (note 14) $ 588.3 $ 460.8 Fair value of derivative financial instruments (notes 21 and 23) 388.1 800.3 Funded status of defined benefit pension plans (note 19) 256.4 141.2 Lease ROU assets (note 7) 212.7 237.2 Accrued interest receivable (notes 4 and 5) 167.2 202.2 Leased equipment 118.3 163.7 Assets held in trust for supplemental retirement plans (note 19) 94.5 56.9 Net deferred tax asset (note 14) 63.5 45.8 Economic development investments 33.8 29.1 Other prepaid expenses 26.5 32.7 Current income tax receivable (note 14) 18.6 44.7 Investment in joint venture 14.4 14.7 Loan disbursements in process 7.1 68.0 Mortgage servicing rights 4.3 4.8 Repossessed assets 3.7 5.7 REO: Residential 1.4 3.2 Commercial — 3.6 Other 26.6 37.6 Total other assets $ 2,025.4 $ 2,352.2
Components of Other Liabilities	The components of other liabilities are as follows: As of December 31 (in millions) 2021 2020 Future contingent commitments for affordable housing investments (note 14) $ 264.5 $ 182.4 Lease liabilities (note 7) 246.5 275.3 Fair value of derivative financial instruments (notes 21 and 23) 95.3 170.4 Accrued expenses payable 92.8 82.6 Accrued employee benefits 90.3 72.2 Liabilities for supplemental retirement plans (note 19) 86.8 89.5 Liability for unsettled purchases of securities 45.5 194.8 Reserve for uncertain tax positions (note 14) 32.4 33.4 ACL on off-balance-sheet credit exposures (note 6) 28.4 26.9 Other postretirement plans (note 19) 16.5 17.7 Accrued interest payable 11.0 12.1 Loan payments in process — 28.3 Other 24.7 8.5 Total other liabilities $ 1,034.7 $ 1,194.1

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2021
Financial Services Costs [Abstract]
Schedule of Deposits	The following is an analysis of People’s United’s total deposits by product type: 2021 2020 As of December 31 (dollars in millions) Amount Weighted- Amount Weighted- Non-interest-bearing $ 17,941.1 — % $ 15,881.7 — % Savings 6,733.7 0.02 6,029.7 0.04 Interest-bearing checking and money market 25,383.8 0.12 24,567.5 0.17 Time deposits maturing: Within 3 months 1,444.2 0.57 1,850.6 1.10 After 3 but within 6 months 836.7 0.25 1,155.1 0.68 After 6 months but within 1 year 807.7 0.20 1,464.1 0.75 After 1 but within 2 years 447.6 0.73 950.8 1.02 After 2 but within 3 years 76.2 0.43 165.7 1.75 After 3 but within 4 years 50.6 0.67 18.1 0.99 After 4 but within 5 years 33.7 0.33 54.4 0.68 After 5 years (1) — — — 0.99 Total 3,696.7 0.43 5,658.8 0.92 Total deposits $ 53,755.3 0.09 % $ 52,137.7 0.19 % (1) Amount totaled less than $0.1 million at December 31, 2020 (none at December 31, 2021).
Schedule of Interest Expense on Deposits	Interest expense on deposits is summarized as follows: Years ended December 31 (in millions) 2021 2020 2019 Savings $ 2.0 $ 5.4 $ 13.4 Interest-bearing checking and money market 38.4 86.8 195.9 Time 28.3 95.0 147.6 Total $ 68.7 $ 187.2 $ 356.9

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Summary of Borrowings	People’s United’s borrowings are summarized as follows: 2021 2020 As of December 31 (dollars in millions) Amount Weighted- Amount Weighted- Fixed-rate FHLB advances maturing: After 1 month but within 1 year $ 551.2 0.37 % $ 556.9 0.41 % After 1 but within 2 years 0.5 0.05 1.2 0.50 After 2 but within 3 years — — 0.5 0.05 After 3 but within 4 years 8.5 1.70 — — After 4 but within 5 years 0.7 0.57 8.6 1.70 After 5 years 1.7 0.92 2.5 0.83 Total FHLB advances 562.6 0.39 569.7 0.43 Customer repurchase agreements maturing: Within 1 month 395.2 0.10 452.9 0.14 Total customer repurchase agreements 395.2 0.10 452.9 0.14 Federal funds purchased maturing: Within 1 month — — 125.0 0.07 Total federal funds purchased — — 125.0 0.07 Total borrowings $ 957.8 0.27 % $ 1,147.6 0.28 %
Interest Expense on Borrowings	Interest expense on borrowings consists of the following: Years ended December 31 (in millions) 2021 2020 2019 FHLB advances $ 4.3 $ 13.7 $ 50.1 Customer repurchase agreements 0.4 1.1 2.2 Federal funds purchased — 5.4 24.6 Other borrowings — — 0.1 Total $ 4.7 $ 20.2 $ 77.0
Information Concerning Parent Company Borrowings	Information concerning People’s United’s borrowings is presented below: As of and for the years ended December 31 (dollars in millions) 2021 2020 2019 FHLB advances: Balance at year end $ 562.6 $ 569.7 $ 3,125.4 Average outstanding during the year 569.6 1,371.2 2,098.0 Maximum outstanding at any month end 569.7 4,489.7 3,125.5 Average interest rate during the year 0.75 % 1.00 % 2.39 % Customer repurchase agreements: Balance at year end $ 395.2 $ 452.9 $ 409.1 Carrying amount of collateral securities at year end 403.1 462.0 418.0 Average outstanding during the year 394.3 379.0 296.6 Maximum outstanding at any month end 436.2 452.9 409.1 Average interest rate during the year 0.11 % 0.29 % 0.75 % Federal funds purchased: Balance at year end $ — $ 125.0 $ 1,620.0 Average outstanding during the year 52.8 688.2 1,127.5 Maximum outstanding at any month end 150.0 1,692.0 1,665.0 Average interest rate during the year 0.09 % 0.79 % 2.18 % Other borrowings: Balance at year end $ — $ — $ — Average outstanding during the year — — 3.3 Maximum outstanding at any month end — — 10.4 Average interest rate during the year — % — % 1.87 %

Notes and Debentures (Tables)

Notes and Debentures (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Subordinated Borrowing	Notes and debentures are summarized as follows: As of December 31 (in millions) 2021 2020 People’s United Financial, Inc.: 3.65% senior notes due 2022 $ 499.6 $ 498.9 5.75% subordinated notes due 2024 78.8 80.2 People’s United Bank: 4.00% subordinated notes due 2024 414.4 430.5 Total notes and debentures $ 992.8 $ 1,009.6

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Summary of Total Income Tax Expense	The following is a summary of total income tax expense: Years ended December 31 (in millions) 2021 2020 2019 Income tax expense applicable to pre-tax income $ 152.3 $ 129.0 $ 132.0 Deferred income tax (benefit) expense applicable to items reported in (16.5) 24.1 27.2 Total $ 135.8 $ 153.1 $ 159.2
Income Tax Effects Related to Items Recognized in Other Comprehensive Income	The components of income tax expense applicable to pre-tax income are summarized as follows: Years ended December 31 (in millions) 2021 2020 2019 Current tax expense: Federal $ 116.0 $ 113.4 $ 90.8 State 33.7 34.3 26.9 Total current tax expense 149.7 147.7 117.7 Deferred tax expense (benefit) (1) 2.6 (18.7) 14.3 Total income tax expense $ 152.3 $ 129.0 $ 132.0 (1) Includes the effect of decreases in the valuation allowance for state deferred tax assets of $6.2 million, $13.7 million and $7.7 million in 2021, 2020 and 2019, respectively.
Summary of Income Tax Reconciliation	The following is a reconciliation of expected income tax expense, computed at the U.S. federal statutory rate of 21% to actual income tax expense: 2021 2020 2019 Years ended December 31 (dollars in millions) Amount Rate Amount Rate Amount Rate Expected income tax expense $ 159.0 21.0 % $ 73.2 21.0 % $ 137.0 21.0 % State income tax, net of federal tax effect 27.1 3.6 23.9 6.8 22.6 3.4 Non-deductible FDIC insurance premiums 4.8 0.6 5.8 1.6 4.4 0.7 Tax-exempt interest (22.7) (3.0) (22.0) (6.3) (21.4) (3.3) Federal income tax credits (14.8) (1.9) (14.8) (4.2) (12.7) (2.0) Tax-exempt income from BOLI (2.4) (0.3) (2.7) (0.8) (2.2) (0.3) Tax benefits recognized in connection with: Equity-based compensation (0.5) (0.1) 1.3 0.4 (0.1) — Release of CT valuation allowance — — (7.1) (2.1) — — Non-deductible goodwill impairment (1) — — 74.1 21.3 — — Other, net 1.8 0.2 (2.7) (0.7) 4.4 0.7 Actual income tax expense $ 152.3 $ 129.0 $ 132.0 Effective income tax rate 20.1 % 37.0 % 20.2 % (1) See Note 8.
Deferred Tax Assets and Liabilities	The tax effects of temporary differences that give rise to People’s United’s deferred tax assets and liabilities are as follows: As of December 31 (in millions) 2021 2020 Deferred tax assets: Allowance for credit losses and non-accrual interest $ 96.2 $ 117.3 State tax net operating loss carryforwards, net of federal tax effect 59.6 65.9 Tax credits and net operating loss carryforwards 24.7 24.7 Equity-based compensation 20.3 19.9 Acquisition-related deferred tax assets 12.8 12.7 ROU lease assets, net of lease liabilities 7.6 8.6 D.C. Solar investment basis difference 6.8 6.8 Unrealized loss on debt securities available-for-sale 6.3 — Unrealized loss on debt securities transferred to held-to-maturity 1.4 2.5 Other deductible temporary differences 33.3 26.6 Total deferred tax assets 269.0 285.0 Less: valuation allowance for state deferred tax assets (52.5) (58.7) Total deferred tax assets, net of the valuation allowance 216.5 226.3 Deferred tax liabilities: Leasing activities (69.3) (88.3) Pension and other postretirement benefits (57.3) (25.6) Book over tax income recognized on consumer loans (17.2) (17.2) Mark-to-market and original issue discounts for tax purposes (3.7) (1.8) Temporary differences related to merchant services joint venture (3.3) (3.5) Unrealized gain on debt securities available-for-sale — (31.4) Other taxable temporary differences (2.2) (12.7) Total deferred tax liabilities (153.0) (180.5) Net deferred tax asset $ 63.5 $ 45.8
Unrecognized Income Tax Benefits	The following is a reconciliation of the beginning and ending balances of People's United’s unrecognized income tax benefits related to uncertain tax positions: Years ended December 31 (in millions) 2021 2020 2019 Balance at beginning of year $ 33.4 $ 33.3 $ 5.2 Additions for tax positions taken in prior years — 0.1 0.5 Additions related to D.C. Solar: Established by United Financial prior to acquisition — — 8.7 Established by People's United subsequent to acquisition — — 18.9 Reductions attributable to audit settlements/lapse of statute of limitations (1) (1.0) — — Balance at end of year $ 32.4 $ 33.4 $ 33.3 (1) Reflects the resolution of a state tax apportionment matter arising as a result of a change in state tax legislation.

Regulatory Capital Requiremen_2

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2021
Financial Services Costs [Abstract]
Regulatory Capital Requirements	The following is a summary of People's United’s and the Bank's regulatory capital amounts and ratios under the Basel III capital rules. The minimum capital required amounts are based on the capital conservation buffer of the Basel III capital rules. In connection with the adoption of the Basel III capital rules, both the Company and the Bank elected to opt-out of the requirement to include most components of AOCL in CET 1 capital. At December 31, 2021, People's United's and the Bank's total risk-weighted assets, as defined, were both $41.8 billion compared to $45.1 billion and $45.0 billion, respectively, at December 31, 2020. For regulatory capital purposes, PPP loans are assigned a zero risk-weighting as a result of the related SBA guarantee on such loans. As of December 31, 2021 Minimum Capital Classification as (dollars in millions) Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Capital (1): People’s United $ 5,326.7 8.5 % $ 2,502.0 4.0 % N/A N/A Bank 5,403.6 8.6 2,501.8 4.0 $ 3,127.2 5.0 % CET 1 Risk-Based Capital (2): People’s United 5,082.6 12.2 2,925.6 7.0 N/A N/A Bank 5,403.6 12.9 2,925.0 7.0 2,716.0 6.5 Tier 1 Risk-Based Capital (3): People’s United 5,326.7 12.7 3,552.5 8.5 2,507.6 6.0 Bank 5,403.6 12.9 3,551.7 8.5 3,342.8 8.0 Total Risk-Based Capital (4): People’s United 5,793.3 13.9 4,388.3 10.5 4,179.4 10.0 Bank 5,840.2 14.0 4,387.4 10.5 4,178.5 10.0 As of December 31, 2020 Minimum Capital Classification as (dollars in millions) Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Capital (1): People’s United $ 4,967.8 8.3 % $ 2,388.4 4.0 % N/A N/A Bank 5,168.4 8.7 2,387.9 4.0 $ 2,984.8 5.0 % CET 1 Risk-Based Capital (2): People’s United 4,723.7 10.5 3,155.3 7.0 N/A N/A Bank 5,168.4 11.5 3,151.1 7.0 2,926.0 6.5 Tier 1 Risk-Based Capital (3): People’s United 4,967.8 11.0 3,831.4 8.5 2,704.5 6.0 Bank 5,168.4 11.5 3,826.3 8.5 3,601.3 8.0 Total Risk-Based Capital (4): People’s United 5,589.5 12.4 4,732.9 10.5 4,507.5 10.0 Bank 5,745.1 12.8 4,726.7 10.5 4,501.6 10.0 (1) Tier 1 Leverage Capital ratio represents CET 1 Capital plus Additional Tier 1 Capital instruments (together, (2) CET 1 Risk-Based Capital ratio represents equity capital, as defined, less: (i) after-tax net unrealized gains (losses) on certain securities classified as available-for-sale; (ii) after-tax net unrealized gains (losses) on securities transferred to held-to-maturity; (iii) goodwill and other acquisition-related intangible assets; and (iv) the amount recorded in AOCL relating to pension and other postretirement benefits divided by Total Risk-Weighted Assets. (3) Tier 1 Risk-Based Capital ratio represents Tier 1 Capital divided by Total Risk-Weighted Assets. (4) Total Risk-Based Capital ratio represents Tier 1 Capital plus subordinated notes and debentures, up to certain limits, and the ACL, up to 1.25% of Total Risk-Weighted Assets, divided by Total Risk-Weighted Assets.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Common Share, Reflecting Application of Two-Class Method	The following is an analysis of People’s United’s basic and diluted EPS, reflecting the application of the two-class method, as described in Note 1: Years ended December 31 (in millions, except per common share data) 2021 2020 2019 Net income available to common shareholders $ 590.8 $ 205.5 $ 506.3 Dividends paid on and undistributed earnings allocated — — (0.2) Earnings attributable to common shareholders $ 590.8 $ 205.5 $ 506.1 Weighted average common shares outstanding for basic EPS 420.8 420.3 394.0 Effect of dilutive equity-based awards 3.7 2.3 3.2 Weighted average common shares and common-equivalent 424.5 422.6 397.2 EPS: Basic $ 1.40 $ 0.49 $ 1.28 Diluted 1.39 0.49 1.27

Comprehensive Income (Tables)

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	The following is a summary of the changes in the components of AOCL, which are included in People’s United’s stockholders’ equity on an after-tax basis: (in millions) Pension Net Unrealized Net Unrealized Net Unrealized Total Balance at December 31, 2018 $ (192.5) $ (47.0) $ (15.3) $ (2.0) $ (256.8) Other comprehensive income (loss) 9.7 67.9 — 1.5 79.1 Amounts reclassified from AOCL (1) 6.6 (0.1) 3.5 0.8 10.8 Current period other comprehensive 16.3 67.8 3.5 2.3 89.9 Balance at December 31, 2019 (176.2) 20.8 (11.8) 0.3 (166.9) Other comprehensive income (loss) (12.0) 82.3 — (1.0) 69.3 Amounts reclassified from AOCL (1) 6.4 — 3.6 (1.6) 8.4 Current period other comprehensive (5.6) 82.3 3.6 (2.6) 77.7 Balance at December 31, 2020 (181.8) 103.1 (8.2) (2.3) (89.2) Other comprehensive income (loss) 61.7 (122.4) — 0.9 (59.8) Amounts reclassified from AOCL (1) 7.0 — 3.8 1.4 12.2 Current period other comprehensive 68.7 (122.4) 3.8 2.3 (47.6) Balance at December 31, 2021 $ (113.1) $ (19.3) $ (4.4) $ — $ (136.8) (1) See the following table for details about these reclassifications.
Summary of Amounts Reclassified from AOCL	The following is a summary of the amounts reclassified from AOCL: Years ended December 31 (in millions) Amounts Reclassified Affected Line Item 2021 2020 2019 Details about components of AOCL: Amortization of pension and Net actuarial loss $ (9.0) $ (8.4) $ (8.3) (1) (9.0) (8.4) (8.3) Income before income tax expense 2.0 2.0 1.7 Income tax expense (7.0) (6.4) (6.6) Net income Reclassification adjustment for net — — 0.1 Income before income tax expense (2) — — — Income tax expense — — 0.1 Net income Amortization of unrealized losses on (4.9) (4.7) (4.6) Income before income tax expense (3) 1.1 1.1 1.1 Income tax expense (3.8) (3.6) (3.5) Net income Amortization of unrealized gains and Interest rate swaps (1.9) 1.9 (1.2) (4) Interest rate locks 0.1 0.1 0.1 (4) (1.8) 2.0 (1.1) Income before income tax expense 0.4 (0.4) 0.3 Income tax expense (1.4) 1.6 (0.8) Net income Total reclassifications for the period $ (12.2) $ (8.4) $ (10.8) (1) Included in the computation of net periodic benefit income (expense) reflected in other non-interest expense (see Note 19 for additional details). (2) Included in non-interest income. (3) Included in interest and dividend income — securities. (4) Included in interest expense — notes and debentures.
Deferred Income Taxes Applicable to Components of Accumulated Other Comprehensive Loss	Deferred income taxes applicable to the components of AOCL are as follows: As of December 31 (in millions) 2021 2020 2019 Net actuarial loss and other amounts related to pension and $ 36.9 $ 57.0 $ 55.3 Net unrealized loss (gain) on debt securities available-for-sale 6.3 (32.1) (6.6) Net unrealized loss on debt securities transferred to held-to-maturity 1.4 2.5 3.6 Net unrealized loss (gain) on derivatives accounted for as cash flow hedges — 0.7 (0.1) Total deferred income taxes $ 44.6 $ 28.1 $ 52.2
Other Comprehensive Income (Loss)	The following is a summary of the components of People’s United’s total other comprehensive income (loss): Year ended December 31, 2021 (in millions) Pre-Tax Tax Effect After-Tax Net actuarial gains and losses on pension and other postretirement plans: Net actuarial gain arising during the year $ 79.8 $ (18.1) $ 61.7 Reclassification adjustment for net actuarial loss included in net income 9.0 (2.0) 7.0 Net actuarial gain 88.8 (20.1) 68.7 Net unrealized gains and losses on debt securities available-for-sale: Net unrealized holding losses arising during the year (160.8) 38.4 (122.4) Net unrealized losses (160.8) 38.4 (122.4) Net unrealized gains and losses on debt securities transferred to held-to-maturity: Reclassification adjustment for amortization of unrealized losses on debt 4.9 (1.1) 3.8 Net unrealized gains 4.9 (1.1) 3.8 Net unrealized gains and losses on derivatives accounted for as cash flow hedges: Net unrealized gains arising during the year 1.2 (0.3) 0.9 Reclassification adjustment for net realized losses included in net income 1.8 (0.4) 1.4 Net unrealized gains 3.0 (0.7) 2.3 Total other comprehensive loss $ (64.1) $ 16.5 $ (47.6) Year ended December 31, 2020 (in millions) Pre-Tax Tax Effect After-Tax Net actuarial gains and losses on pension and other postretirement plans: Net actuarial loss arising during the year $ (15.7) $ 3.7 $ (12.0) Reclassification adjustment for net actuarial loss included in net income 8.4 (2.0) 6.4 Net actuarial loss (7.3) 1.7 (5.6) Net unrealized gains and losses on debt securities available-for-sale: Net unrealized holding gains arising during the year 107.8 (25.5) 82.3 Net unrealized gains 107.8 (25.5) 82.3 Net unrealized gains and losses on debt securities transferred to held-to-maturity: Reclassification adjustment for amortization of unrealized losses on debt 4.7 (1.1) 3.6 Net unrealized gains 4.7 (1.1) 3.6 Net unrealized gains and losses on derivatives accounted for as cash flow hedges: Net unrealized losses arising during the year (1.4) 0.4 (1.0) Reclassification adjustment for net realized gains included in net income (2.0) 0.4 (1.6) Net unrealized losses (3.4) 0.8 (2.6) Total other comprehensive income $ 101.8 $ (24.1) $ 77.7 Year ended December 31, 2019 (in millions) Pre-Tax Tax Effect After-Tax Net actuarial gains and losses on pension and other postretirement plans: Net actuarial gain arising during the year $ 12.1 $ (2.4) $ 9.7 Reclassification adjustment for net actuarial loss included in net income 8.3 (1.7) 6.6 Net actuarial gain 20.4 (4.1) 16.3 Net unrealized gains and losses on debt securities available-for-sale: Net unrealized holding gains arising during the year 89.2 (21.3) 67.9 Reclassification adjustment for net realized losses included in net income (0.1) — (0.1) Net unrealized gains 89.1 (21.3) 67.8 Net unrealized gains and losses on debt securities transferred to held-to-maturity: Reclassification adjustment for amortization of unrealized losses on debt 4.6 (1.1) 3.5 Net unrealized gains 4.6 (1.1) 3.5 Net unrealized gains and losses on derivatives accounted for as cash flow hedges: Net unrealized gains arising during the year 1.9 (0.4) 1.5 Reclassification adjustment for net realized losses included in net income 1.1 (0.3) 0.8 Net unrealized gains 3.0 (0.7) 2.3 Total other comprehensive income $ 117.1 $ (27.2) $ 89.9

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Changes in Benefit Obligations and Plan Assets	The following table summarizes changes in the benefit obligations and plan assets of (i) the Qualified Plan, the People's Supplemental Plans, the First Connecticut Supplemental Plan, the BSB Bancorp Supplemental Plan and the United Financial Supplemental Plan (together the “Pension Plans”) and (ii) the People’s Postretirement Plan, the First Connecticut Postretirement Plans, the BSB Bancorp Post Retirement Welfare (Life Insurance) Plan and the United Financial Postretirement Benefit Plan (together the “Other Postretirement Plans”). The table also shows the funded status (or the difference between benefit obligations and plan assets) recognized in the Consolidated Statements of Condition. All plans have a December 31 measurement date. Pension Plans Other (in millions) 2021 2020 2021 2020 Benefit obligations: (1) Beginning of year $ 740.5 $ 665.5 $ 17.7 $ 18.7 Service cost — — 0.3 0.3 Interest cost 16.2 19.7 0.4 0.6 Actuarial loss (gain) (24.8) 85.9 (1.3) (1.5) Benefits paid (29.6) (30.0) (0.6) (0.4) Settlements (2.7) (0.6) — — End of year 699.6 740.5 16.5 17.7 Fair value of plan assets: Beginning of year 839.9 746.7 — — Actual return on assets 107.7 120.2 — — Employer contributions 5.4 3.6 0.6 0.4 Benefits paid (29.6) (30.0) (0.6) (0.4) Settlements (2.7) (0.6) — — End of year 920.7 839.9 — — Funded status at end of year $ 221.1 $ 99.4 $ (16.5) $ (17.7) Amounts recognized in the Consolidated Statements Other assets $ 256.4 $ 141.2 $ — $ — Other liabilities (35.3) (41.8) (16.5) (17.7) Funded status at end of year $ 221.1 $ 99.4 $ (16.5) $ (17.7) (1) Represents the projected benefit obligation for the Pension Plans and the accumulated benefit obligation for the Other Postretirement Plans.
Accumulated and Projected Benefit Obligations	The following table summarizes the accumulated and projected benefit obligations for the Pension Plans at the respective measurement dates: Pension Plans As of December 31 (in millions) 2021 2020 Accumulated benefit obligations: Qualified Plan $ 664.3 $ 698.7 Supplemental Plans 35.0 41.6 Total $ 699.3 $ 740.3 Projected benefit obligations: Qualified Plan $ 664.3 $ 698.7 Supplemental Plans 35.3 41.8 Total $ 699.6 $ 740.5
Components of Net Periodic Benefit (Income) Expense and Other Amounts	Components of net periodic benefit (income) expense and other amounts recognized in other comprehensive income (loss) are as follows: Pension Plans Other Years ended December 31 (in millions) 2021 2020 2019 2021 2020 2019 Net periodic benefit (income) expense: Interest cost $ 16.2 $ 19.7 $ 22.9 $ 0.7 $ 0.9 $ 0.9 Expected return on plan assets (54.2) (49.5) (46.1) — — — Recognized net actuarial loss 8.2 7.9 5.3 — 0.2 0.1 Settlements (1) 0.8 0.2 2.9 — — — Net periodic benefit (income) expense (29.0) (21.7) (15.0) 0.7 1.1 1.0 Other changes in plan assets and benefit obligations Net actuarial (gain) loss (87.3) 7.5 (20.5) (1.3) (1.6) 1.1 Total pre-tax changes recognized in other (87.3) 7.5 (20.5) (1.3) (1.6) 1.1 Total recognized in net periodic benefit $ (116.3) $ (14.2) $ (35.5) $ (0.6) $ (0.5) $ 2.1 (1) Settlement charges are a result of lump-sum benefit payments in excess of the sum of a plan’s annual interest and service costs. When an employer settles the full amount of its obligation for vested benefits with respect to some of a plan’s participants, the employer is required to recognize in income a pro-rata portion of the aggregate gain or loss recorded in AOCL.
Pre-Tax Amounts in Accumulated Other Comprehensive Loss	The pre-tax amounts in AOCL that have not been recognized as components of net periodic benefit (income) expense are as follows: Pension Plans Other As of December 31 (in millions) 2021 2020 2021 2020 Net actuarial loss $ 148.7 $ 236.0 $ 1.0 $ 2.3 Total pre-tax amounts included in AOCL $ 148.7 $ 236.0 $ 1.0 $ 2.3
Assumptions Used in Determining Benefit Obligations and Net Periodic Benefit Expense	The following assumptions were used in determining the benefit obligations and net periodic benefit (income) expense as of and for the periods indicated: Qualified Plans Other Postretirement Plans 2021 2020 2019 2021 2020 2019 Weighted-average assumptions used to determine Discount rate: People’s Qualified Plan 2.86 % 2.50 % 3.38 % 2.90 % 2.50 % 3.40 % First Connecticut Qualified Plan (1) n/a n/a 3.39 n/a n/a n/a United Financial Qualified Plan (2) n/a 2.53 3.42 n/a n/a n/a Rate of compensation increase n/a n/a n/a n/a n/a n/a Weighted-average assumptions used to determine net Discount rate: People’s Qualified Plan (3) 2.50%/3.14% 3.38 % 4.41 % 2.50 % 3.40 % 4.40 % First Connecticut Qualified Plan (1) n/a 3.39 4.41 n/a n/a n/a United Financial Qualified Plan (2) 2.53 3.42 3.33 n/a n/a n/a Expected return on plan assets: People’s Qualified Plan 7.25 7.25 7.25 n/a n/a n/a First Connecticut Qualified Plan (1) n/a n/a 6.00 n/a n/a n/a United Financial Qualified Plan (2) 5.25 5.25 5.25 n/a n/a n/a Rate of compensation increase n/a n/a n/a n/a n/a n/a Assumed health care cost trend rates at December 31: Health care cost trend rate assumed for next year n/a n/a n/a 5.20 % 5.50 % 5.70 % Rate to which the cost trend rate is assumed to n/a n/a n/a 4.50 4.50 4.50 Year that the rate reaches the ultimate trend rate n/a n/a n/a 2037 2037 2037 n/a — not applicable (1) Effective December 31, 2020, the First Connecticut Qualified Plan was merged into the People’s Qualified Plan. (2) Effective March 31, 2021, the United Financial Qualified Plan was merged into the People’s Qualified Plan. (3) Rate of 2.50% through March 31, 2021 and 3.14% through December 31, 2021.
Asset Allocation	All investment decisions are governed by an established policy that contains the following asset allocation guidelines: Asset Class Policy Target % Policy Range % Cash equivalents 1 0-20 Equity securities 71 55-75 Fixed income securities 28 10-40
Fair Value of Assets in Qualified Plans	The following table summarizes the percentages of fair value for the major categories of assets in the qualified plans as of the respective measurement dates: Plan Assets 2021 2020 As of December 31 People’s United Financial People’s United Financial Equity securities 70 % n/a 70 % 4 % Cash and fixed income securities 30 n/a 30 96 Total 100 % n/a 100 % 100 % (1) Effective March 31, 2021, the United Financial Qualified Plan was merged into the People’s Qualified Plan. (2) The United Financial Qualified Plan was not yet aligned with the Company's investment strategy and asset allocation guidelines as the acquisition of United Financial occurred effective November 1, 2019.
Plan Assets Measured at Fair Value	The following tables present the Qualified Plan’s assets measured at fair value: Fair Value Measurements Using As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 41.5 $ — $ — $ 41.5 Equity securities: Common stocks 353.5 — — 353.5 Mutual funds — 287.1 — 287.1 Fixed income securities: Mutual funds — 118.1 — 118.1 Corporate — 75.8 — 75.8 U.S. Treasury — 43.9 — 43.9 Other — 0.8 — 0.8 Total $ 395.0 $ 525.7 $ — $ 920.7 Fair Value Measurements Using As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 23.9 $ — $ — $ 23.9 Equity securities: Common stocks 302.6 — — 302.6 Mutual funds — 259.6 — 259.6 Fixed income securities: Mutual funds — 103.3 — 103.3 Corporate — 96.5 — 96.5 U.S. Treasury — 52.5 — 52.5 Other — 1.5 — 1.5 Total $ 326.5 $ 513.4 $ — $ 839.9

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Performance Share Activity	The following is a summary of performance share activity under the 2014 Plan: Shares Weighted-Average Unvested performance shares outstanding at December 31, 2018 1,453,372 $ 17.85 Granted 637,118 17.84 Forfeited (80,319) 18.66 Vested (505,755) 15.23 Unvested performance shares outstanding at December 31, 2019 1,504,416 18.68 Granted 691,989 16.75 Change in shares based on approved performance factors 79,623 18.60 Forfeited (55,378) 17.90 Vested (501,569) 18.60 Unvested performance shares outstanding at December 31, 2020 1,719,081 17.94 Granted 832,965 15.57 Change in shares based on approved performance factors 94,341 19.71 Forfeited (43,032) 16.44 Vested (569,476) 19.77 Unvested performance shares outstanding at December 31, 2021 2,033,879 $ 16.58
Stock Option Incentive Plan	The following is a summary of stock option activity under the Incentive Plans and the SOP: Shares Weighted-Average Weighted-Average Aggregate Options outstanding at December 31, 2018 14,677,067 $ 15.87 Granted 2,807,692 17.62 Forfeited (652,965) 18.28 Exercised (1,632,971) 14.77 Options outstanding at December 31, 2019 15,198,823 16.20 Granted 3,419,934 16.21 Forfeited (552,726) 16.65 Exercised (43,759) 14.91 Options outstanding at December 31, 2020 18,022,272 16.19 Granted 2,322,549 15.29 Forfeited (221,074) 17.24 Exercised (2,790,967) 14.50 Options outstanding at December 31, 2021 17,332,780 $ 16.33 5.7 $ 32.4 Options exercisable at December 31, 2021 12,134,430 $ 16.46 4.6 $ 22.6 (1) Reflects only those stock options with intrinsic value at December 31, 2021.
Options Outstanding and Options Exercisable	Additional information concerning options outstanding and options exercisable at December 31, 2021 is summarized as follows: Exercise Price Range Options Outstanding Options Exercisable Weighted-Average Number Remaining Exercise Number Weighted-Average $11.29 — $14.71 3,708,487 2.8 $ 14.04 3,704,519 $ 14.04 14.72 — 15.75 4,565,982 6.1 15.07 2,305,988 14.85 15.76 — 18.40 5,303,025 7.7 16.81 2,368,637 17.08 18.41 — 19.71 3,755,286 5.6 19.45 3,755,286 19.45
Restricted Stock Award Incentive Plan	The following is a summary of restricted stock award activity under the Incentive Plans and the RRP: Shares Weighted-Average Unvested restricted shares outstanding at December 31, 2018 730,550 $ 18.03 Granted 383,420 17.44 Forfeited (68,091) 17.11 Vested (347,078) 17.49 Unvested restricted shares outstanding at December 31, 2019 698,801 18.07 Granted 562,739 14.60 Forfeited (28,090) 17.31 Vested (326,878) 18.33 Unvested restricted shares outstanding at December 31, 2020 906,572 15.85 Granted 474,766 15.29 Forfeited (54,921) 15.07 Vested (411,720) 16.59 Unvested restricted shares outstanding at December 31, 2021 914,697 $ 15.27

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables summarize People’s United’s financial instruments that are measured at fair value on a recurring basis: Fair Value Measurements Using As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Debt securities available-for-sale: U.S. Treasury and agency $ 636.7 $ — $ — $ 636.7 GSE mortgage-backed and CMO securities — 6,007.3 — 6,007.3 Other assets: Exchange-traded funds 89.2 — — 89.2 Mutual funds 5.3 — — 5.3 Interest rate swaps — 384.0 — 384.0 Interest rate caps — 1.7 — 1.7 Foreign exchange contracts — 2.4 — 2.4 Forward commitments to sell residential — — — — Total $ 731.2 $ 6,395.4 $ — $ 7,126.6 Financial liabilities: Interest rate swaps $ — $ 90.8 $ — $ 90.8 Interest rate caps — 1.7 — 1.7 Risk participation agreements — 0.2 — 0.2 Foreign exchange contracts — 2.6 — 2.6 Interest rate-lock commitments on residential — — — — Total $ — $ 95.3 $ — $ 95.3 Fair Value Measurements Using As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Debt securities available-for-sale: U.S. Treasury and agency $ 541.6 $ — $ — $ 541.6 GSE mortgage-backed securities — 4,383.9 — 4,383.9 Equity securities 5.3 — — 5.3 Other assets: Exchange-traded funds 53.0 — — 53.0 Mutual funds 3.9 — — 3.9 Interest rate swaps — 783.8 — 783.8 Interest rate caps — 3.0 — 3.0 Foreign exchange contracts — 12.8 — 12.8 Forward commitments to sell residential mortgage loans — 0.7 — 0.7 Total $ 603.8 $ 5,184.2 $ — $ 5,788.0 Financial liabilities: Interest rate swaps $ — $ 157.2 $ — $ 157.2 Interest rate caps — 3.0 — 3.0 Risk participation agreements — 0.4 — 0.4 Foreign exchange contracts — 8.8 — 8.8 Interest rate-lock commitments on residential mortgage loans — 1.0 — 1.0 Total $ — $ 170.4 $ — $ 170.4 (1) Fair value totaled less than $0.1 million at December 31, 2021.
Assets Measured at Fair Value on Non-Recurring Basis	The following tables summarize People’s United’s assets that are measured at fair value on a non-recurring basis: Fair Value Measurements Using As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Loans held-for-sale (1) $ — $ 8.8 $ — $ 8.8 Collateral dependent loans (2) — — 25.3 25.3 REO and repossessed assets (3) — — 5.1 5.1 Mortgage servicing rights (4) — — 4.3 4.3 Total $ — $ 8.8 $ 34.7 $ 43.5 Fair Value Measurements Using As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Goodwill (5) $ — $ — $ 2,680.8 $ 2,680.8 Loans held-for-sale (1) — 26.5 — 26.5 Collateral dependent loans (2) — — 32.8 32.8 REO and repossessed assets (3) — — 12.5 12.5 Mortgage servicing rights (4) — — 4.8 4.8 Total $ — $ 26.5 $ 2,730.9 $ 2,757.4 (1) Consists of residential mortgage loans; no fair value adjustments were recorded for the years ended December 31, 2021 and 2020. (2) Represents the recorded investment in collateral dependent loans with a related ACL totaling $13.6 million and $20.5 million at December 31, 2021 and 2020, respectively, measured in accordance with applicable accounting guidance. The provision for credit losses on collateral dependent loans totaled $3.6 million and $22.0 million for the years ended December 31, 2021 and 2020, respectively. (3) Represents: (i) $3.7 million of repossessed assets and (ii) $1.4 million of residential REO at December 31, 2021. (4) Fair value adjustments totaling $(0.5) million and $(5.8) million were recorded for the years ended December 31, 2021 and 2020, respectively.
Carrying Amounts and Estimated Fair Values of Financial Instruments	The following tables summarize the carrying amounts, estimated fair values and placement in the fair value hierarchy of People’s United’s financial instruments that are not measured at fair value either on a recurring or non-recurring basis: Carrying Estimated Fair Value As of December 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Cash and due from banks $ 320.5 $ 320.5 $ — $ — $ 320.5 Short-term investments 10,268.8 — 10,268.8 — 10,268.8 Debt securities held-to-maturity, net 3,841.5 — 4,034.6 1.5 4,036.1 FRB and FHLB stock 264.6 — 264.6 — 264.6 Total loans, net (1) 37,482.4 — 6,906.6 30,636.5 37,543.1 Financial liabilities: Time deposits 3,696.7 — 3,703.3 — 3,703.3 Other deposits 50,058.6 — 50,058.6 — 50,058.6 FHLB advances 562.6 — 562.7 — 562.7 Customer repurchase agreements 395.2 — 395.2 — 395.2 Notes and debentures 992.8 — 1,010.6 — 1,010.6 Carrying Estimated Fair Value As of December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Financial assets: Cash and due from banks $ 477.3 $ 477.3 $ — $ — $ 477.3 Short-term investments 3,766.0 — 3,766.0 — 3,766.0 Debt securities held-to-maturity 3,993.8 — 4,265.5 1.5 4,267.0 FRB and FHLB stock 266.6 — 266.6 — 266.6 Total loans, net (1) 43,411.6 — 8,539.4 35,294.0 43,833.4 Financial liabilities: Time deposits 5,658.8 — 5,699.7 — 5,699.7 Other deposits 46,478.9 — 46,478.9 — 46,478.9 FHLB advances 569.7 — 570.3 — 570.3 Customer repurchase agreements 452.9 — 452.9 — 452.9 Federal funds purchased 125.0 — 125.0 — 125.0 Notes and debentures 1,009.6 — 1,035.8 — 1,035.8 (1) Excludes collateral dependent loans measured at fair value on a non-recurring basis totaling $25.3 million and $32.8 million at December 31, 2021 and 2020, respectively.

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, All Other Investments [Abstract]
Summary of Contractual or Notional Amounts of Financial Instruments	A summary of the contractual or notional amounts of People’s United’s lending-related and derivative financial instruments follows: As of December 31 (in millions) 2021 2020 Lending-Related Financial Instruments: (1) Loan origination commitments and unadvanced lines of credit: Commercial and industrial $ 8,332.8 $ 6,723.5 Home equity and other consumer 3,536.5 3,349.5 Commercial real estate 795.1 962.4 Equipment financing 655.6 437.6 Residential mortgage 18.9 44.6 Letters of credit: Stand-by 156.0 150.4 Commercial 4.2 4.5 Derivative Financial Instruments: (2) Interest rate swaps: For market risk management 925.0 925.0 For commercial customers: Customer 8,469.9 8,878.6 Institutional counterparties 8,478.3 8,881.3 Interest rate caps: For commercial customers: Customer 163.7 185.1 Institutional counterparties 163.7 185.1 Risk participation agreements 903.2 924.3 Foreign exchange contracts 321.8 285.3 Forward commitments to sell residential mortgage loans 0.7 25.4 Interest rate-lock commitments on residential mortgage loans 0.7 41.5 (1) The contractual amounts of these financial instruments represent People’s United’s maximum potential exposure to credit loss, assuming: (i) the instruments are fully funded at a later date; (ii) the borrower does not meet contractual repayment obligations; and (iii) any collateral or other security proves to be worthless. (2) The contractual or notional amounts of these financial instruments are substantially greater than People’s United’s maximum potential exposure to credit loss.
Schedule of Notional Amounts and Fair Values of Derivatives Outstanding	The table below provides a summary of the notional amounts and fair values (presented on a gross basis) of derivatives outstanding: Fair Values (1) Type of Notional Amounts Assets Liabilities As of December 31 (in millions) 2021 2020 2021 2020 2021 2020 Derivatives Not Designated as Hedging Interest rate swaps: Commercial customers N/A $ 8,469.9 $ 8,878.6 $ 359.7 $ 778.0 $ 15.8 $ 0.4 Institutional counterparties N/A 8,478.3 8,881.3 24.3 5.8 75.0 156.8 Interest rate caps: Commercial customers N/A 163.7 185.1 1.4 3.0 0.3 — Institutional counterparties N/A 163.7 185.1 0.3 — 1.4 3.0 Risk participation agreements N/A 903.2 924.3 — — 0.2 0.4 Foreign exchange contracts N/A 321.8 285.3 2.4 12.8 2.6 8.8 Forward commitments to sell N/A 0.7 25.4 — 0.7 — — Interest rate-lock commitments on N/A 0.7 41.5 — — — 1.0 Total 388.1 800.3 95.3 170.4 Derivatives Designated as Hedging Interest rate swaps: FHLB advances Cash flow 550.0 550.0 — — — — Subordinated notes Fair value 375.0 375.0 — — — — Total — — — — Total fair value of $ 388.1 $ 800.3 $ 95.3 $ 170.4 (1) Assets are recorded in other assets and liabilities are recorded in other liabilities. (2) Fair value totaled less than $0.1 million at December 31, 2021.
Impact of Derivatives on Pre-Tax Income and Accumulated Other Comprehensive Loss	The following table summarizes the impact of People’s United’s derivatives on pre-tax income and AOCL: Type of Amount of Pre-Tax Gain (Loss) Amount of Pre-Tax Gain (Loss) Years ended December 31 (in millions) 2021 2020 2019 2021 2020 2019 Derivatives Not Designated as Interest rate swaps: Commercial customers N/A $ (236.3) $ 614.8 $ 374.9 $ — $ — $ — Institutional counterparties N/A 241.1 (599.4) (350.3) — — — Interest rate caps: Commercial customers N/A (1.2) 1.4 1.4 — — — Institutional counterparties N/A 1.8 (1.4) (1.5) — — — Foreign exchange contracts N/A 1.4 1.0 1.0 — — — Risk participation agreements N/A 0.1 (0.5) (0.4) — — — Forward commitments to sell N/A (0.7) 0.3 0.3 — — — Interest rate-lock commitments on N/A 1.0 (0.5) (0.4) — — — Total 7.2 15.7 25.0 — — — Derivatives Designated as Interest rate swaps Fair value 9.7 5.9 0.3 — — — Interest rate swaps Cash flow (1.9) 1.9 (1.2) 1.2 (1.3) 1.9 Interest rate locks Cash flow 0.1 0.1 0.1 — — — Total 7.9 7.9 (0.8) 1.2 (1.3) 1.9 Total $ 15.1 $ 23.6 $ 24.2 $ 1.2 $ (1.3) $ 1.9 (1) Amounts recognized in earnings are recorded in interest income, interest expense or other non-interest income for derivatives designated as hedging instruments and in other non-interest income for derivatives not designated as hedging instruments.

Balance Sheet Offsetting (Table

Balance Sheet Offsetting (Tables)	12 Months Ended
	Dec. 31, 2021
Offsetting [Abstract]
Summary of Gross Presentation, Financial Instruments that are Eligible for Offset Not Offset in Consolidated Statement of Condition	The following tables provide a gross presentation, the effects of offsetting, and a net presentation of the Company’s financial instruments that are eligible for offset in the Consolidated Statements of Condition. The collateral amounts in these tables are limited to the outstanding balances of the related asset or liability (after netting is applied) and, therefore, instances of overcollateralization are not presented. In the tables below, the Net Amount Presented of the derivative assets and liabilities can be reconciled to the fair value of the Company’s derivative financial instruments in Note 23. The Company’s derivative contracts with commercial customers and customer repurchase agreements are not subject to master netting arrangements and, therefore, have been excluded from the tables below. Gross Gross Net Gross Amounts Not Offset Net As of December 31, 2021 (in millions) Financial Collateral Financial assets: Interest rate swaps/caps: Counterparty A $ 0.1 $ — $ 0.1 $ (0.1) $ — $ — Counterparty B — — — — — — Counterparty C 1.7 — 1.7 (1.7) — — Counterparty D 0.6 — 0.6 (0.6) — — Counterparty E 20.0 — 20.0 — — 20.0 Other counterparties 2.2 — 2.2 (1.7) (0.4) 0.1 Foreign exchange contracts 2.4 — 2.4 — — 2.4 Total $ 27.0 $ — $ 27.0 $ (4.1) $ (0.4) $ 22.5 Financial liabilities: Interest rate swaps/caps: Counterparty A $ 2.3 $ — $ 2.3 $ (0.1) $ (2.2) $ — Counterparty B 3.6 — 3.6 — (3.6) — Counterparty C 28.8 — 28.8 (1.7) (27.1) — Counterparty D 9.6 — 9.6 (0.6) (8.7) 0.3 Counterparty E — — — — — — Other counterparties 32.1 — 32.1 (1.7) (30.4) — Foreign exchange contracts 2.6 — 2.6 — — 2.6 Total $ 79.0 $ — $ 79.0 $ (4.1) $ (72.0) $ 2.9 Gross Gross Net Gross Amounts Not Offset Net As of December 31, 2020 (in millions) Financial Collateral Financial assets: Interest rate swaps/caps: Counterparty A $ — $ — $ — $ — $ — $ — Counterparty B — — — — — — Counterparty C 0.3 — 0.3 (0.3) — — Counterparty D — — — — — — Counterparty E 5.4 — 5.4 — — 5.4 Other counterparties 0.1 — 0.1 (0.1) — — Foreign exchange contracts 12.8 — 12.8 — — 12.8 Total $ 18.6 $ — $ 18.6 $ (0.4) $ — $ 18.2 Financial liabilities: Interest rate swaps/caps: Counterparty A $ 5.6 $ — $ 5.6 $ — $ (5.6) $ — Counterparty B 7.1 — 7.1 — (7.1) — Counterparty C 56.6 — 56.6 (0.3) (56.3) — Counterparty D 21.4 — 21.4 — (10.4) 11.0 Counterparty E — — — — — — Other counterparties 69.1 — 69.1 (0.1) (69.0) — Foreign exchange contracts 8.8 — 8.8 — — 8.8 Total $ 168.6 $ — $ 168.6 $ (0.4) $ (148.4) $ 19.8
Summary of Collateral Swaps	The following tables show the extent to which assets and liabilities exchanged under resale and repurchase agreements have been offset in the Consolidated Statements of Condition. These agreements: (i) are entered into simultaneously with the same financial institution counterparty; (ii) have the same principal amounts and inception/maturity dates; and (iii) are subject to a master netting arrangement that contains a conditional right of offset upon default. At December 31, 2021 and 2020, the Company posted as collateral marketable securities with fair values of $252.9 million and $258.7 million, respectively, and, in turn, accepted as collateral marketable securities with fair values of $258.9 million and $254.4 million, respectively. As of December 31, 2021 (in millions) Gross Gross Net Total resale agreements $ 250.0 $ (250.0) $ — Total repurchase agreements $ 250.0 $ (250.0) $ — As of December 31, 2020 (in millions) Gross Gross Net Total resale agreements $ 250.0 $ (250.0) $ — Total repurchase agreements $ 250.0 $ (250.0) $ —

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Selected Financial Information Business Segments	The following tables provide selected financial information for People’s United’s reportable segments: Year ended December 31, 2021 (in millions) Commercial Retail Total Treasury Other Total Net interest income (loss) $ 1,145.1 $ 677.6 $ 1,822.7 $ (317.8) $ (5.8) $ 1,499.1 Provision for credit losses 52.9 8.5 61.4 (0.1) (109.6) (48.3) Total non-interest income 172.4 195.7 368.1 14.8 10.7 393.6 Total non-interest expense 452.0 651.8 1,103.8 2.4 77.6 1,183.8 Income (loss) before income tax 812.6 213.0 1,025.6 (305.3) 36.9 757.2 Income tax expense (benefit) 162.8 42.6 205.4 (61.0) 7.9 152.3 Net income (loss) $ 649.8 $ 170.4 $ 820.2 $ (244.3) $ 29.0 $ 604.9 Average total assets $ 33,644.4 $ 10,923.9 $ 44,568.3 $ 17,946.9 $ 1,737.9 $ 64,253.1 Average total liabilities 19,466.3 28,915.0 48,381.3 7,274.9 893.9 56,550.1 Year ended December 31, 2020 (in millions) Commercial Retail Total Treasury Other Total Net interest income (loss) $ 1,098.9 $ 634.9 $ 1,733.8 $ (118.5) $ (39.5) $ 1,575.8 Provision for credit losses 52.8 10.0 62.8 (0.3) 93.3 155.8 Total non-interest income 217.3 182.2 399.5 7.8 85.4 492.7 Total non-interest expense (1) 478.5 1,009.4 1,487.9 3.7 72.5 1,564.1 Income (loss) before income tax 784.9 (202.3) 582.6 (114.1) (119.9) 348.6 Income tax expense (benefit) 144.7 27.4 172.1 (19.8) (23.3) 129.0 Net income (loss) $ 640.2 $ (229.7) $ 410.5 $ (94.3) $ (96.6) $ 219.6 Average total assets $ 35,946.3 $ 13,447.3 $ 49,393.6 $ 9,988.1 $ 1,656.4 $ 61,038.1 Average total liabilities 16,524.6 26,978.3 43,502.9 8,863.8 859.6 53,226.3 (1) Retail Banking includes a $353.0 million non-cash goodwill impairment charge (see Note 8). Year ended December 31, 2019 (in millions) Commercial Retail Total Treasury Other Total Net interest income (loss) $ 807.1 $ 555.1 $ 1,362.2 $ 66.5 $ (16.4) $ 1,412.3 Provision for credit losses 44.1 8.9 53.0 — (24.7) 28.3 Total non-interest income 206.5 195.9 402.4 14.1 14.6 431.1 Total non-interest expense 448.7 600.2 1,048.9 13.8 100.0 1,162.7 Income (loss) before income tax 520.8 141.9 662.7 66.8 (77.1) 652.4 Income tax expense (benefit) 104.3 28.5 132.8 13.5 (14.3) 132.0 Net income (loss) $ 416.5 $ 113.4 $ 529.9 $ 53.3 $ (62.8) $ 520.4 Average total assets $ 29,746.8 $ 12,560.9 $ 42,307.7 $ 7,882.3 $ 1,468.0 $ 51,658.0 Average total liabilities 11,490.2 23,397.7 34,887.9 9,011.9 686.9 44,586.7

Parent Company Financial Info_2

Parent Company Financial Information (Tables) - People's United Financial, Inc.	12 Months Ended
	Dec. 31, 2021
Condensed Balance Sheet Statements, Captions [Line Items]
Condensed Statements of Condition	CONDENSED STATEMENTS OF CONDITION As of December 31 (in millions) 2021 2020 Assets: Cash at bank subsidiary $ 490.2 $ 305.3 Total cash and cash equivalents 490.2 305.3 Equity securities, at fair value — 5.3 Investments in subsidiaries: Bank subsidiary 7,775.6 7,600.3 Non-bank subsidiaries 10.1 7.3 Goodwill 203.0 203.0 Due from bank subsidiary 5.8 3.1 Other assets 0.2 62.2 Total assets $ 8,484.9 $ 8,186.5 Liabilities and Stockholders’ Equity: Notes and debentures $ 578.4 $ 579.1 Other liabilities 4.7 4.6 Stockholders’ equity 7,901.8 7,602.8 Total liabilities and stockholders’ equity $ 8,484.9 $ 8,186.5
Condensed Statements of Income	CONDENSED STATEMENTS OF INCOME Years ended December 31 (in millions) 2021 2020 2019 Revenues: Dividend income from subsidiaries: Bank subsidiary $ 437.0 $ 498.0 $ 457.0 Non-bank subsidiaries 2.5 — — Interest income 0.1 0.3 0.4 Non-interest income 1.1 (0.8) 1.7 Total revenues 440.7 497.5 459.1 Expenses: Interest on notes and debentures 21.7 21.7 19.2 Non-interest expense 20.0 8.5 14.1 Total expenses 41.7 30.2 33.3 Income before income tax benefit and subsidiaries 399.0 467.3 425.8 Income tax benefit (8.5) (6.5) (6.2) Income before subsidiaries undistributed income 407.5 473.8 432.0 Subsidiaries undistributed income (distributions in excess of income) 197.4 (254.2) 88.4 Net income $ 604.9 $ 219.6 $ 520.4
Condensed Statements of Comprehensive Income	CONDENSED STATEMENTS OF COMPREHENSIVE INCOME Years ended December 31 (in millions) 2021 2020 2019 Net income $ 604.9 $ 219.6 $ 520.4 Other comprehensive (loss) income, net of tax: Net unrealized losses on derivatives accounted for as cash flow hedges (0.1) (0.1) (0.1) Other comprehensive (loss) income of bank subsidiary (47.5) 77.8 90.0 Total other comprehensive (loss) income, net of tax (47.6) 77.7 89.9 Total comprehensive income $ 557.3 $ 297.3 $ 610.3
Condensed Statements of Cash Flows	CONDENSED STATEMENTS OF CASH FLOWS Years ended December 31 (in millions) 2021 2020 2019 Cash Flows from Operating Activities: Net income $ 604.9 $ 219.6 $ 520.4 Adjustments to reconcile net income to net cash provided Subsidiaries (undistributed income) distributions in excess of income (197.4) 254.2 (88.4) Net change in other assets and other liabilities 58.4 (2.1) (0.7) Net cash provided by operating activities 465.9 471.7 431.3 Cash Flows from Investing Activities: Proceeds from sales of equity securities 6.4 2.0 1.6 Net cash provided by investing activities 6.4 2.0 1.6 Cash Flows from Financing Activities: Cash dividends paid on common stock (307.8) (304.1) (274.8) Cash dividends paid on preferred stock (14.1) (14.1) (14.1) Common stock repurchases (2.1) (306.1) (4.5) Proceeds from stock options exercised 36.6 0.7 24.1 Net cash used in financing activities (287.4) (623.6) (269.3) Net increase (decrease) in cash and cash equivalents 184.9 (149.9) 163.6 Cash and cash equivalents at beginning of year 305.3 455.2 291.6 Cash and cash equivalents at end of year $ 490.2 $ 305.3 $ 455.2

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	The following table presents People’s United’s quarterly financial data for 2021 and 2020: 2021 (1) 2020 (1) (dollars in millions, except First Second Third Fourth First Second Third Fourth Interest and dividend income $ 417.0 $ 406.3 $ 393.8 $ 384.2 $ 499.1 $ 457.6 $ 436.8 $ 421.5 Interest expense 31.1 25.4 23.5 22.2 103.1 52.0 45.4 38.7 Net interest income 385.9 380.9 370.3 362.0 396.0 405.6 391.4 382.8 Provision for credit losses (13.6) (40.8) 12.1 (6.0) 33.5 80.8 26.8 14.7 Net interest income after 399.5 421.7 358.2 368.0 362.5 324.8 364.6 368.1 Non-interest income 94.6 99.0 100.4 99.6 123.8 89.6 101.1 178.2 Non-interest expense 311.9 305.0 289.2 277.7 320.1 304.0 293.6 646.4 Income (loss) before income 182.2 215.7 169.4 189.9 166.2 110.4 172.1 (100.1) Income tax expense 37.7 44.9 29.7 40.0 35.8 20.5 27.5 45.2 Net income (loss) 144.5 170.8 139.7 149.9 130.4 89.9 144.6 (145.3) Preferred stock dividend 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 Net income (loss) available to $ 141.0 $ 167.3 $ 136.2 $ 146.4 $ 126.9 $ 86.4 $ 141.1 $ (148.8) Common Share Data: EPS: Basic $ 0.34 $ 0.40 $ 0.32 $ 0.35 $ 0.30 $ 0.21 $ 0.34 $ (0.36) Diluted 0.33 0.39 0.32 0.34 0.30 0.21 0.34 (0.35) Common dividends paid 75.7 77.3 77.4 77.4 77.3 75.5 75.7 75.6 Dividends paid per 0.1800 0.1825 0.1825 0.1825 0.1775 0.1800 0.1800 0.1800 Common dividend payout ratio 53.7 % 46.2 % 56.8 % 52.9 % 60.9 % 87.4 % 53.6 % (50.8) % Stock price: High $ 19.40 $ 19.62 $ 18.08 $ 19.05 $ 17.00 $ 13.99 $ 12.36 $ 13.58 Low 12.66 16.75 15.18 16.20 10.40 9.37 9.74 9.98 Weighted average common shares Basic 419.12 421.09 421.43 421.65 427.18 417.91 418.05 418.15 Diluted 422.58 425.08 424.77 425.45 429.77 420.15 420.29 420.39 (1) The sum of the quarterly amounts for certain line items may not equal the full-year amounts due to rounding.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended								12 Months Ended
	Dec. 31, 2021USD ($)	Sep. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2021USD ($)segment	Dec. 31, 2021USD ($)Reporting_Unit	Dec. 31, 2021USD ($)Segment	Dec. 31, 2020USD ($)Reporting_Unit	Dec. 31, 2019USD ($)Reporting_Unit
Summary Of Significant Accounting Policies [Line Items]
Number of days of non accrual status									90 days
Accruing interest total	$ 0				$ 0				$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Non-interest income	$ 99,600,000	$ 100,400,000	$ 99,000,000	$ 94,600,000	$ 178,200,000	$ 101,100,000	$ 89,600,000	$ 123,800,000		$ 393,600,000				$ 492,700,000	$ 431,100,000
Non-interest income percentage	70.00%				56.00%				70.00%	70.00%	70.00%	70.00%	70.00%	56.00%	67.00%
Number of primary operating segments											3		3
Number of reporting units | Reporting_Unit												3		3	3
Percent of loans using LIBOR	50.00%								50.00%	50.00%	50.00%	50.00%	50.00%
Operating Segments
Summary Of Significant Accounting Policies [Line Items]
Non-interest income										$ 368,100,000				$ 399,500,000	$ 402,400,000
Significant Revenue Streams
Summary Of Significant Accounting Policies [Line Items]
Non-interest income										276,000,000				277,000,000	288,000,000
Trade name intangible | Accelerated Amortization
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life, (in years)									20 years
Trade name intangible | Straight Line Amortization
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life, (in years)									5 years
Commercial Banking | Operating Segments
Summary Of Significant Accounting Policies [Line Items]
Non-interest income										$ 172,400,000				$ 217,300,000	$ 206,500,000
Non-interest income percentage	35.00%				40.00%				35.00%	35.00%	35.00%	35.00%	35.00%	40.00%	40.00%
Retail Banking | Operating Segments
Summary Of Significant Accounting Policies [Line Items]
Non-interest income										$ 195,700,000				$ 182,200,000	$ 195,900,000
Non-interest income percentage	35.00%				30.00%				35.00%	35.00%	35.00%	35.00%	35.00%	30.00%	30.00%
Wealth Management | Operating Segments
Summary Of Significant Accounting Policies [Line Items]
Non-interest income percentage	30.00%				30.00%				30.00%	30.00%	30.00%	30.00%	30.00%	30.00%	30.00%
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									10 years
Building
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									40 years
Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									10 years
Minimum
Summary Of Significant Accounting Policies [Line Items]
Loan agreement									6 months
Minimum | Core deposit intangible
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life, (in years)									6 years
Minimum | Trust relationships
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life, (in years)									10 years
Minimum | Data Processing and Other Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									3 years
Minimum | Computer Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Term of contract with customers									1 year
Maximum | Core deposit intangible
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life, (in years)									10 years
Maximum | Trust relationships
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life, (in years)									15 years
Maximum | Data Processing and Other Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									5 years
Maximum | Computer Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, (in years)									5 years

Acquisitions and Dispositions -

Acquisitions and Dispositions - Additional Information (Detail) shares in Millions, $ in Millions	Nov. 02, 2020USD ($)	Nov. 01, 2019USD ($)branchshares	Oct. 25, 2019USD ($)branch	Apr. 01, 2019USD ($)branchshares	Dec. 31, 2021USD ($)branch	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Aug. 05, 2021branch	Feb. 22, 2021	Jan. 21, 2021branch	Jan. 02, 2019USD ($)
Business Acquisition [Line Items]
Shares conversion ratio									0.118
Number of branches operated | branch					111
Contract termination costs					$ 24.2
Connecticut And New York
Business Acquisition [Line Items]
Number of branches operated | branch										140
Connecticut
Business Acquisition [Line Items]
Number of branches operated | branch					84
Number of branches retained | branch								27
New York State
Business Acquisition [Line Items]
Number of branches operated | branch					27
People's United Insurance Agency
Business Acquisition [Line Items]
Transaction amount	$ 120
Value of assets	58.5
Goodwill	31.7
Intangible assets	3.2
Value of liabilities	14.4
Gain on disposal	$ 75.9
Central Maine Branch Sale
Business Acquisition [Line Items]
Gain on disposal			$ 7.6
Number of branches sold | branch			8
Loans sold			$ 103
Deposits sold			258
Assets under management sold			$ 227
M&T Bank Corporation
Business Acquisition [Line Items]
Merger-related expenses					$ 22.3
United Financial
Business Acquisition [Line Items]
Merger-related expenses					43.3	$ 22.2
Business acquisition consideration transferred		$ 720.6
Business acquisition common stock shares (in shares) | shares		44.4
Number of branches acquired | branch		58
Assets acquired		$ 7,220
Liabilities acquired		$ 6,500
BSB Bancorp
Business Acquisition [Line Items]
Merger-related expenses					$ 0.4	$ 8.1
Business acquisition consideration transferred				$ 324.5
Business acquisition common stock shares (in shares) | shares				19.7
Number of branches acquired | branch				6
Assets acquired				$ 3,190
Liabilities acquired				$ 2,860
VAR Technology Finance
Business Acquisition [Line Items]
Loans											$ 60
Payments for merger related costs							$ 1.9

Cash and Cash Equivalents - Add

Cash and Cash Equivalents - Additional Information (Detail)	Dec. 31, 2021	Dec. 31, 2020
FHLB of New York
Cash and Cash Equivalents [Line Items]
Interest rate	0.15%	0.10%

Cash and Cash Equivalents - Cas

Cash and Cash Equivalents - Cash and Short-Term Investments (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Interest-bearing deposits at the FRB-NY	$ 10,180.8	$ 3,598.9
Collateral posted for derivative instruments	73.4	151.9
Money market mutual funds	14.1	8.9
Other	0.5	6.3
Total short-term investments	$ 10,268.8	$ 3,766

Securities - Available-for-Sale

Securities - Available-for-Sale and Held-to-Maturity Debt Securities Gains (Losses) (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt securities available-for-sale:
Amortized Cost	$ 6,687.9	$ 4,804.5
Allowance for credit loss	0	0
Gross Unrealized Gains	55.7	122.7
Gross Unrealized Losses	(99.6)	(1.7)
Fair Value	6,644	4,925.5
Debt securities held-to-maturity:
Amortized Cost	3,843	3,995.4
Allowance for credit loss	(1.5)	(1.6)	$ 0
Gross Unrealized Gains	197.7	273.4
Gross Unrealized Losses	(3.1)	(0.2)
Fair Value	4,036.1	4,267
U.S. Treasury and agency
Debt securities available-for-sale:
Amortized Cost	632.7	529.8
Allowance for credit loss	0	0
Gross Unrealized Gains	4	11.8
Gross Unrealized Losses	0	0
Fair Value	636.7	541.6
Debt securities held-to-maturity:
Amortized Cost	0
Fair Value	0
GSE mortgage-backed securities
Debt securities available-for-sale:
Amortized Cost	6,055.2	4,274.7
Allowance for credit loss	0	0
Gross Unrealized Gains	51.7	110.9
Gross Unrealized Losses	(99.6)	(1.7)
Fair Value	6,007.3	4,383.9
Debt securities held-to-maturity:
Amortized Cost	893.5	1,079.9
Allowance for credit loss	0	0
Gross Unrealized Gains	15.6	36.4
Gross Unrealized Losses	0	0
Fair Value	909.1	1,116.3
State and municipal
Debt securities available-for-sale:
Amortized Cost	0
Fair Value	0
Debt securities held-to-maturity:
Amortized Cost	2,865.2	2,824.3
Allowance for credit loss	(0.1)	(0.1)	0
Gross Unrealized Gains	180.4	236
Gross Unrealized Losses	(3)	0
Fair Value	3,042.5	3,060.2
Corporate
Debt securities available-for-sale:
Amortized Cost	0
Fair Value	0
Debt securities held-to-maturity:
Amortized Cost	82.8	89.7
Allowance for credit loss	(1.4)	(1.5)	$ 0
Gross Unrealized Gains	1.7	1
Gross Unrealized Losses	(0.1)	(0.2)
Fair Value	83	89
Other
Debt securities available-for-sale:
Amortized Cost	0
Fair Value	0
Debt securities held-to-maturity:
Amortized Cost	1.5	1.5
Allowance for credit loss	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 1.5	$ 1.5

Securities - Additional Informa

Securities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021USD ($)Securitybranch	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Investment [Line Items]
Debt securities, available-for-sale, accrued interest receivable	$ 12,600,000	$ 10,700,000
Debt securities, held-to-maturity, accrued interest receivable	31,900,000	31,500,000
Debt securities, held-to-maturity, nonaccrual	0	0
Debt securities with unrealized losses	$ 99,600,000	1,700,000
Number of debt securities classified as available-for-sale | Security	172
Percentage of available for sale debt securities with loss position	42.00%
Number of debt securities owned | branch	412
Available-for-sale unrealized losses	$ 99,600,000	1,700,000
Impairment of investments	0	0	$ 0
Debt security available for sale with fair values pledged with collateral for public deposits	3,540,000,000	4,930,000,000
Debt security available for sale with a held-to-maturity pledged with collateral for public deposits	$ 1,730,000,000	2,080,000,000
Weighted average tax rate equivalent	24.60%
Unrealized loss on equity securities	$ (300,000)	(1,100,000)
Unrealized gain on equity securities			1,500,000
Federal Reserve Bank stock percentage	6.00%
Impairment of investments	$ 0
Dividend income on capital stock	209,700,000	195,700,000	186,500,000
Maximum
Investment [Line Items]
Debt securities with unrealized losses	100,000
Investment in Federal Home Loan Bank Stock
Investment [Line Items]
Impairment of investments	0
Dividend income on capital stock	600,000	4,800,000	7,000,000
FHLB of New York
Investment [Line Items]
Acquired shares of capital stock	229,100,000	228,400,000
Dividend income on capital stock	3,400,000	2,000,000	$ 3,800,000
FHLB of Boston
Investment [Line Items]
Acquired shares of capital stock	35,500,000	38,200,000
GSE mortgage-backed securities
Investment [Line Items]
Debt securities with unrealized losses	99,600,000	1,700,000
Available-for-sale unrealized losses	$ 99,600,000	$ 1,700,000
Available for sale securities average maturity period	23 years

Securities - Allowance for Cred

Securities - Allowance for Credit Loss on Held-to-Maturity Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 1.6	$ 0
Provision for credit losses on securities (note 4)	(0.1)	(0.3)	$ 0
Balance at end of period	1.5	1.6	0
Cumulative Effect, Period of Adoption, Adjustment
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0	1.9
Balance at end of period		0	1.9
Cumulative Effect, Period of Adoption, Adjusted Balance
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	1.6	1.9
Balance at end of period		1.6	1.9
Corporate
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	1.5	0
Provision for credit losses on securities (note 4)	(0.1)	(0.3)
Balance at end of period	1.4	1.5	0
Corporate | Cumulative Effect, Period of Adoption, Adjustment
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0	1.8
Balance at end of period		0	1.8
Corporate | Cumulative Effect, Period of Adoption, Adjusted Balance
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	1.5	1.8
Balance at end of period		1.5	1.8
State and municipal
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0.1	0
Provision for credit losses on securities (note 4)	0	0
Balance at end of period	0.1	0.1	0
State and municipal | Cumulative Effect, Period of Adoption, Adjustment
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0	0.1
Balance at end of period		0	0.1
State and municipal | Cumulative Effect, Period of Adoption, Adjusted Balance
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 0.1	0.1
Balance at end of period		$ 0.1	$ 0.1

Securities - Debt Securities He

Securities - Debt Securities Held-to-maturity Credit Quality (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Investment [Line Items]
Debt securities held-to-maturity, net	$ 3,843	$ 3,995.4
Internal Investment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	3,837.8	3,990.2
Internal Noninvestment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	5.2	5.2
State and municipal
Investment [Line Items]
Debt securities held-to-maturity, net	2,865.2	2,824.3
State and municipal | Internal Investment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	2,865	2,824.1
State and municipal | Internal Noninvestment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	0.2	0.2
GSE mortgage-backed securities
Investment [Line Items]
Debt securities held-to-maturity, net	893.5	1,079.9
GSE mortgage-backed securities | Internal Investment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	893.5	1,079.9
GSE mortgage-backed securities | Internal Noninvestment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	0	0
Corporate
Investment [Line Items]
Debt securities held-to-maturity, net	82.8	89.7
Corporate | Internal Investment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	77.8	84.7
Corporate | Internal Noninvestment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	5	5
Other
Investment [Line Items]
Debt securities held-to-maturity, net	1.5	1.5
Other | Internal Investment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	1.5	1.5
Other | Internal Noninvestment Grade
Investment [Line Items]
Debt securities held-to-maturity, net	$ 0	$ 0

Securities - Continuous Unreali

Securities - Continuous Unrealized Loss Position on Available-for-Sale and Held-to-Maturities Securities (Detail) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Available-for-sale, Fair Value
Less Than 12 Months	$ 2,993,400,000	$ 225,500,000
12 Months Or Longer	1,120,900,000	0
Total	4,114,300,000	225,500,000
Available-for-sale, Unrealized Losses
Less Than 12 Months	(55,200,000)	(1,700,000)
12 Months Or Longer	(44,400,000)	0
Total	(99,600,000)	(1,700,000)
GSE mortgage-backed securities
Available-for-sale, Fair Value
Less Than 12 Months	2,978,300,000	225,500,000
12 Months Or Longer	1,120,900,000	0
Total	4,099,200,000	225,500,000
Available-for-sale, Unrealized Losses
Less Than 12 Months	(55,200,000)	(1,700,000)
12 Months Or Longer	(44,400,000)	0
Total	(99,600,000)	$ (1,700,000)
U.S. Treasury and agency
Available-for-sale, Fair Value
Less Than 12 Months	15,100,000
12 Months Or Longer	0
Total	15,100,000
Available-for-sale, Unrealized Losses
Less Than 12 Months	0
12 Months Or Longer	0
Total	0
Maximum
Available-for-sale, Unrealized Losses
Total	$ (100,000)

Securities - Summary of Amortiz

Securities - Summary of Amortized Cost and Fair Value of Debt Securities Based on Remaining Period to Contractual Maturity (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Available for sale amortized cost
Within 1 year	$ 389.3
After 1 but within 5 years	337.2
After 5 but within 10 years	1,448.7
After 10 years	4,512.7
Amortized Cost	6,687.9	$ 4,804.5
Available for sale fair value
Within 1 year	391.9
After 1 but within 5 years	342.2
After 5 but within 10 years	1,458.8
After 10 years	4,451.1
Fair value	$ 6,644	4,925.5
Available for sale FTE yield
Within 1 year	1.44%
After 1 but within 5 years	1.74%
After 5 but within 10 years	1.96%
After 10 years	1.56%
Total	1.65%
Held-to-maturity amortized cost
Within 1 year	$ 88.7
After 1 but within 5 years	939.9
After 5 but within 10 years	1,016.5
After 10 years	1,797.9
Amortized Cost	3,843	3,995.4
Held-to-maturity fair value
Within 1 year	89.5
After 1 but within 5 years	958.3
After 5 but within 10 years	1,078.4
After 10 years	1,909.9
Fair value	$ 4,036.1	4,267
Held-to-maturity FTE yield
Within 1 year	2.63%
After 1 but within 5 years	2.54%
After 5 but within 10 years	3.56%
After 10 years	3.45%
Total	3.24%
U.S. Treasury and agency
Available for sale amortized cost
Within 1 year	$ 372.3
After 1 but within 5 years	260.4
Amortized Cost	632.7	529.8
Available for sale fair value
Within 1 year	374.9
After 1 but within 5 years	261.8
Fair value	$ 636.7	541.6
Available for sale FTE yield
Within 1 year	1.36%
After 1 but within 5 years	1.34%
Total	1.35%
Held-to-maturity amortized cost
Within 1 year	$ 0
After 1 but within 5 years	0
Amortized Cost	0
Held-to-maturity fair value
Within 1 year	0
After 1 but within 5 years	0
Fair value	$ 0
Held-to-maturity FTE yield
Within 1 year	0.00%
After 1 but within 5 years	0.00%
Total	0.00%
GSE mortgage-backed securities
Available for sale amortized cost
Within 1 year	$ 17
After 1 but within 5 years	76.8
After 5 but within 10 years	1,448.7
After 10 years	4,512.7
Amortized Cost	6,055.2	4,274.7
Available for sale fair value
Within 1 year	17
After 1 but within 5 years	80.4
After 5 but within 10 years	1,458.8
After 10 years	4,451.1
Fair value	$ 6,007.3	4,383.9
Available for sale FTE yield
Within 1 year	3.15%
After 1 but within 5 years	3.11%
After 5 but within 10 years	1.96%
After 10 years	1.56%
Total	1.68%
Held-to-maturity amortized cost
Within 1 year	$ 43.9
After 1 but within 5 years	705.7
After 5 but within 10 years	143.9
After 10 years	0
Amortized Cost	893.5	1,079.9
Held-to-maturity fair value
Within 1 year	44.2
After 1 but within 5 years	716.6
After 5 but within 10 years	148.3
After 10 years	0
Fair value	$ 909.1	1,116.3
Held-to-maturity FTE yield
Within 1 year	2.21%
After 1 but within 5 years	2.45%
After 5 but within 10 years	2.23%
After 10 years	0.00%
Total	2.40%
State and municipal
Available for sale amortized cost
Within 1 year	$ 0
After 1 but within 5 years	0
After 5 but within 10 years	0
After 10 years	0
Amortized Cost	0
Available for sale fair value
Within 1 year	0
After 1 but within 5 years	0
After 5 but within 10 years	0
After 10 years	0
Fair value	$ 0
Available for sale FTE yield
Within 1 year	0.00%
After 1 but within 5 years	0.00%
After 5 but within 10 years	0.00%
After 10 years	0.00%
Total	0.00%
Held-to-maturity amortized cost
Within 1 year	$ 43.8
After 1 but within 5 years	220.9
After 5 but within 10 years	802.6
After 10 years	1,797.9
Amortized Cost	2,865.2	2,824.3
Held-to-maturity fair value
Within 1 year	44.3
After 1 but within 5 years	228.4
After 5 but within 10 years	859.9
After 10 years	1,909.9
Fair value	$ 3,042.5	3,060.2
Held-to-maturity FTE yield
Within 1 year	3.06%
After 1 but within 5 years	2.84%
After 5 but within 10 years	3.70%
After 10 years	3.45%
Total	3.47%
Corporate
Available for sale amortized cost
Within 1 year	$ 0
After 1 but within 5 years	0
After 5 but within 10 years	0
Amortized Cost	0
Available for sale fair value
Within 1 year	0
After 1 but within 5 years	0
After 5 but within 10 years	0
Fair value	$ 0
Available for sale FTE yield
Within 1 year	0.00%
After 1 but within 5 years	0.00%
After 5 but within 10 years	0.00%
Total	0.00%
Held-to-maturity amortized cost
Within 1 year	$ 1
After 1 but within 5 years	11.8
After 5 but within 10 years	70
Amortized Cost	82.8	89.7
Held-to-maturity fair value
Within 1 year	1
After 1 but within 5 years	11.8
After 5 but within 10 years	70.2
Fair value	$ 83	89
Held-to-maturity FTE yield
Within 1 year	2.67%
After 1 but within 5 years	2.60%
After 5 but within 10 years	4.66%
Total	4.34%
Other
Available for sale amortized cost
After 1 but within 5 years	$ 0
Amortized Cost	0
Available for sale fair value
After 1 but within 5 years	0
Fair value	$ 0
Available for sale FTE yield
After 1 but within 5 years	0.00%
Total	0.00%
Held-to-maturity amortized cost
After 1 but within 5 years	$ 1.5
Amortized Cost	1.5	1.5
Held-to-maturity fair value
After 1 but within 5 years	1.5
Fair value	$ 1.5	$ 1.5
Held-to-maturity FTE yield
After 1 but within 5 years	1.75%
Total	1.75%

Securities - Schedule of Compon

Securities - Schedule of Components of Net Security Losses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt securities:
Gains	$ 2.1	$ 0	$ 0.5
Losses	(2.1)	0	(0.4)
Total debt securities	0	0	0.1
Trading debt securities:
Gains (1)	0	0	0.1
Losses	0	0	0
Total trading debt securities	0	0	0.1
Net security gains	0	0	$ 0.2
U.S. Treasury and CMO Securities
Trading debt securities:
Net security gains	$ 0
Maximum | U.S. Treasury and CMO Securities
Trading debt securities:
Net security gains		$ 0.1

Loans - Additional Information

Loans - Additional Information (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020USD ($)	Dec. 31, 2021USD ($)segmentRating	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of segments (in segments) | segment		2
Net deferred loan costs		$ 65.3	$ 68.1
Construction loans		845.8	1,200
Interest-only residential mortgage loans		595.5	866.4
Net gains on sales of residential mortgage loans		1.6	4.8	$ 1.9
Loans held-for-sale		8.8	26.5
Allowance for loan losses		$ 343.6	425.1	246.6	$ 240.4
Interest rate reduction		2.00%
Collateral values/LTV ratios, minimum		70.00%
Borrower credit scores, minimum | Rating		680
Other Assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, accrued interest		$ 122.7	$ 159.9
Connecticut
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		23.00%
Massachusetts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		19.00%
New York State
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		18.00%
New England
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		53.00%	55.00%
Residential Mortgage Construction Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Construction loans		$ 32.9	$ 44.8
Construction loan not yet advanced		11.9	7.2
Equipment financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Early non-performing loans		$ 68.5	$ 90.1
Equipment financing | Outside New England
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		94.00%	94.00%
Equipment financing | Texas California and New York
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		29.00%
Equipment financing | Outside Texas California and New York
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total loan portfolio representing loans to customers		7.00%
Commercial Construction Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Construction loan not yet advanced		$ 365.4	$ 508.6
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-for-sale		8.8	26.5
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Early non-performing loans		49.2	34
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-for-sale				157.9
Early non-performing loans		29.3	26
Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-for-sale				333.7
Consumer And Commercial Loans | Other Non-Interest Income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gain on sale of loans	$ 16.9
MW/ABL
Accounts, Notes, Loans and Financing Receivable [Line Items]
Early non-performing loans		0.8	1
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, accrued interest, writeoff		0.5	1.3
Allowance for loan losses		$ 201.6	303.6	217.9	209.5
Duration of extension for payment deferral on TDRs, years		3 years
Commercial | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral dependent loans		$ 79.8	71.1
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
CARES Act loan		431.5	2,300
CARES Act deferred loan fees		14.8	45.9
Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, accrued interest, writeoff		0.1	0.2
Allowance for loan losses		$ 142	121.5	28.7	$ 30.9
Duration of extension for payment deferral on TDRs, years		10 years
Retail Loans | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral dependent loans		$ 21	37.8
Non-Performing Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non accrual interest income		2	4.1	2.3
Troubled Debt Restructurings
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in originated loans classified as TDRs		303.2	196.9
Allowance for loan losses		18.4	12
Impaired interest income		6.1	4.6	$ 5.5
Foreclosure or Bankruptcy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Early non-performing loans		$ 26.4	$ 32.6

Loans - Summary of Loans by Loa

Loans - Summary of Loans by Loan Portfolio Segment and Class (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 37,851.3		$ 43,869.5
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	29,131.9		33,249.2
Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,719.4		10,620.3
Commercial real estate | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11,936.7		13,336.9
Commercial real estate | Commercial | Revision of Prior Period, Reclassification, Adjustment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ (350)
Commercial and industrial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,747.6		10,764.1
Commercial and industrial | Commercial | Revision of Prior Period, Reclassification, Adjustment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 350
Equipment financing | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,143.1		4,930
MW/ABL | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,304.5		4,218.2
Residential mortgage | Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,004.3		8,518.9
Adjustable-rate | Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,064.3		5,517.3
Fixed-rate | Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,940		3,001.6
Home equity and other consumer | Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,715.1		2,101.4
Home equity | Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,635.9		1,997.2
Other consumer | Retail Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 79.2		$ 104.2

Loans - Summary of Aging Inform

Loans - Summary of Aging Information by Class of Loan (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	$ 37,851.3	$ 43,869.5
Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	37,635.1	43,571.7
Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	216.2	297.8
30-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	99	149.9
90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	117.2	147.9
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	29,131.9	33,249.2
Commercial | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	11,936.7	13,336.9
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	8,747.6	10,764.1
Commercial | Equipment financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	5,143.1	4,930
Commercial | MW/ABL
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	3,304.5	4,218.2
Commercial | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	28,976.4	33,043.1
Commercial | Financial Asset, Not Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	11,874.4	13,283.2
Commercial | Financial Asset, Not Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	8,717.5	10,694.9
Commercial | Financial Asset, Not Past Due | Equipment financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	5,080	4,846.8
Commercial | Financial Asset, Not Past Due | MW/ABL
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	3,304.5	4,218.2
Commercial | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	155.5	206.1
Commercial | Financial Asset, Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	62.3	53.7
Commercial | Financial Asset, Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	30.1	69.2
Commercial | Financial Asset, Past Due | Equipment financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	63.1	83.2
Commercial | Financial Asset, Past Due | MW/ABL
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Commercial | 30-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	68.4	108.6
Commercial | 30-89 Days | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	6.7	27.3
Commercial | 30-89 Days | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	13.4	17.3
Commercial | 30-89 Days | Equipment financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	48.3	64
Commercial | 30-89 Days | MW/ABL
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Commercial | 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	87.1	97.5
Commercial | 90 Days or More | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	55.6	26.4
Commercial | 90 Days or More | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	16.7	51.9
Commercial | 90 Days or More | Equipment financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	14.8	19.2
Commercial | 90 Days or More | MW/ABL
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0	0
Retail Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	8,719.4	10,620.3
Retail Loans | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	7,004.3	8,518.9
Retail Loans | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,635.9	1,997.2
Retail Loans | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	79.2	104.2
Retail Loans | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	8,658.7	10,528.6
Retail Loans | Financial Asset, Not Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	6,959.2	8,447.9
Retail Loans | Financial Asset, Not Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	1,620.8	1,977.3
Retail Loans | Financial Asset, Not Past Due | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	78.7	103.4
Retail Loans | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	60.7	91.7
Retail Loans | Financial Asset, Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	45.1	71
Retail Loans | Financial Asset, Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	15.1	19.9
Retail Loans | Financial Asset, Past Due | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0.5	0.8
Retail Loans | 30-89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	30.6	41.3
Retail Loans | 30-89 Days | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	22.2	32.2
Retail Loans | 30-89 Days | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	8	8.4
Retail Loans | 30-89 Days | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	0.4	0.7
Retail Loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	30.1	50.4
Retail Loans | 90 Days or More | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	22.9	38.8
Retail Loans | 90 Days or More | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	7.1	11.5
Retail Loans | 90 Days or More | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans	$ 0.1	$ 0.1

Loans - Summarized Recorded Inv

Loans - Summarized Recorded Investments, by Class of Loan, in Originated Non-Performing Loans (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	$ 1.6	$ 16.6
Originated in fiscal year before latest fiscal year	14.4	42.1
Originated two years before latest fiscal year	39.5	41.6
Originated three years before latest fiscal year	47.6	46.5
Originated four years before latest fiscal year	29.3	26.3
Prior	128	113.7
Revolving Loans	2.7	15.7
Revolving Loans Converted to Term	25.4	26.6
Total	288.5	329.1	$ 224.1
Non-Accrual Loans With No ACL	76	75.5
Government guarantees	2.9	2.5	1.3
Foreclosure
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	12.3	23.6	17
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	1.6	16.6
Originated in fiscal year before latest fiscal year	14.1	39.1
Originated two years before latest fiscal year	37.6	37.3
Originated three years before latest fiscal year	42.9	44.5
Originated four years before latest fiscal year	27.9	23.1
Prior	91.5	59.8
Revolving Loans	2.7	15.7
Revolving Loans Converted to Term	13.7	10
Total	232	246.1	140
Non-Accrual Loans With No ACL	$ 56.4	39.3
Guarantee rate	100.00%
Retail Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	$ 0	0
Originated in fiscal year before latest fiscal year	0.3	3
Originated two years before latest fiscal year	1.9	4.3
Originated three years before latest fiscal year	4.7	2
Originated four years before latest fiscal year	1.4	3.2
Prior	36.5	53.9
Revolving Loans	0	0
Revolving Loans Converted to Term	11.7	16.6
Total	56.5	83	84.1
Non-Accrual Loans With No ACL	19.6	36.2
Commercial real estate | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before latest fiscal year	0	8.6
Originated two years before latest fiscal year	10.9	9.7
Originated three years before latest fiscal year	24.6	2.8
Originated four years before latest fiscal year	4.9	1.9
Prior	64.2	35.4
Revolving Loans	0	0.2
Revolving Loans Converted to Term	0.2	1.8
Total	104.8	60.4	53.8
Non-Accrual Loans With No ACL	42.9	10.9
Commercial and industrial | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	0.3	0.2
Originated in fiscal year before latest fiscal year	0.1	3.1
Originated two years before latest fiscal year	5.3	2.3
Originated three years before latest fiscal year	1	16.2
Originated four years before latest fiscal year	4.5	13.4
Prior	16.5	17.5
Revolving Loans	2.7	15.5
Revolving Loans Converted to Term	12.7	7.2
Total	43.1	75.4	38.5
Non-Accrual Loans With No ACL	11.3	27.8
Equipment financing | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	1.3	16.4
Originated in fiscal year before latest fiscal year	14	27.4
Originated two years before latest fiscal year	21.4	25.3
Originated three years before latest fiscal year	17.3	25.5
Originated four years before latest fiscal year	18.5	7.8
Prior	10.8	6.9
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Total	83.3	109.3	47.7
Non-Accrual Loans With No ACL	2.2	0.6
MW/ABL | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before latest fiscal year	0	0
Originated two years before latest fiscal year	0	0
Originated three years before latest fiscal year	0	0
Originated four years before latest fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0.8	1
Total	0.8	1
Non-Accrual Loans With No ACL	0	0
Residential mortgage | Retail Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before latest fiscal year	0.2	2.9
Originated two years before latest fiscal year	1.8	3.9
Originated three years before latest fiscal year	4.3	1.8
Originated four years before latest fiscal year	1.3	2.6
Prior	34.2	51.1
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Total	41.8	62.3	63.3
Non-Accrual Loans With No ACL	14.8	28.3
Home equity | Retail Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before latest fiscal year	0.1	0
Originated two years before latest fiscal year	0	0.4
Originated three years before latest fiscal year	0.4	0.1
Originated four years before latest fiscal year	0.1	0.6
Prior	2.3	2.8
Revolving Loans	0	0
Revolving Loans Converted to Term	11.7	16.6
Total	14.6	20.5	20.8
Non-Accrual Loans With No ACL	4.8	7.9
Other consumer | Retail Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before latest fiscal year	0	0.1
Originated two years before latest fiscal year	0.1	0
Originated three years before latest fiscal year	0	0.1
Originated four years before latest fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Total	0.1	0.2	$ 0
Non-Accrual Loans With No ACL	$ 0	$ 0

Loans - Summary of Recorded Inv

Loans - Summary of Recorded Investments in TDRs by Class of Loan (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)contract	Dec. 31, 2020USD ($)contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	188	202
Pre-Modification Outstanding Recorded Investment	$ 129.4	$ 132.2
Post-Modification Outstanding Recorded Investment	$ 129.4	$ 132.2
Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	64	114
Pre-Modification Outstanding Recorded Investment	$ 107.6	$ 110.2
Post-Modification Outstanding Recorded Investment	$ 107.6	$ 110.2
Retail Loans
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	124	88
Pre-Modification Outstanding Recorded Investment	$ 21.8	$ 22
Post-Modification Outstanding Recorded Investment	$ 21.8	$ 22
Commercial real estate | Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	18	18
Pre-Modification Outstanding Recorded Investment	$ 74.1	$ 16.7
Post-Modification Outstanding Recorded Investment	$ 74.1	$ 16.7
Commercial real estate | Commercial | Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	10	13
Post-Modification Outstanding Recorded Investment	$ 14.9	$ 8.3
Commercial real estate | Commercial | Payment Deferral
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	4	2
Post-Modification Outstanding Recorded Investment	$ 37.8	$ 3.9
Commercial real estate | Commercial | Temporary Rate Reduction
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract		1
Post-Modification Outstanding Recorded Investment		$ 0.4
Commercial real estate | Commercial | Combination of Concessions
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	4	2
Post-Modification Outstanding Recorded Investment	$ 21.4	$ 4.1
Commercial and industrial | Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	25	44
Pre-Modification Outstanding Recorded Investment	$ 26.7	$ 71.5
Post-Modification Outstanding Recorded Investment	$ 26.7	$ 71.5
Commercial and industrial | Commercial | Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	18	23
Post-Modification Outstanding Recorded Investment	$ 16.8	$ 30
Commercial and industrial | Commercial | Payment Deferral
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	2	10
Post-Modification Outstanding Recorded Investment	$ 4.6	$ 36.7
Commercial and industrial | Commercial | Temporary Rate Reduction
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract		2
Post-Modification Outstanding Recorded Investment		$ 0.9
Commercial and industrial | Commercial | Combination of Concessions
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	5	9
Post-Modification Outstanding Recorded Investment	$ 5.3	$ 3.9
Equipment financing | Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	19	43
Pre-Modification Outstanding Recorded Investment	$ 3.8	$ 14.4
Post-Modification Outstanding Recorded Investment	$ 3.8	$ 14.4
Equipment financing | Commercial | Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	11	21
Post-Modification Outstanding Recorded Investment	$ 0.9	$ 5.2
Equipment financing | Commercial | Payment Deferral
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	2	13
Post-Modification Outstanding Recorded Investment	$ 1.5	$ 3.4
Equipment financing | Commercial | Combination of Concessions
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	6	9
Post-Modification Outstanding Recorded Investment	$ 1.4	$ 5.8
MW/ABL | Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	2	9
Pre-Modification Outstanding Recorded Investment	$ 3	$ 7.6
Post-Modification Outstanding Recorded Investment	$ 3	$ 7.6
MW/ABL | Commercial | Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	2	9
Post-Modification Outstanding Recorded Investment	$ 3	$ 7.6
Residential mortgage | Retail Loans
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	55	38
Pre-Modification Outstanding Recorded Investment	$ 17	$ 16.3
Post-Modification Outstanding Recorded Investment	$ 17	$ 16.3
Residential mortgage | Retail Loans | Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	1
Post-Modification Outstanding Recorded Investment	$ 2
Residential mortgage | Retail Loans | Payment Deferral
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	29	12
Post-Modification Outstanding Recorded Investment	$ 8.6	$ 7.3
Residential mortgage | Retail Loans | Combination of Concessions
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	13	16
Post-Modification Outstanding Recorded Investment	$ 4.6	$ 6.6
Residential mortgage | Retail Loans | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	12	10
Post-Modification Outstanding Recorded Investment	$ 1.8	$ 2.4
Home equity | Retail Loans
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	69	50
Pre-Modification Outstanding Recorded Investment	$ 4.8	$ 5.7
Post-Modification Outstanding Recorded Investment	$ 4.8	$ 5.7
Home equity | Retail Loans | Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	4
Post-Modification Outstanding Recorded Investment	$ 0.2
Home equity | Retail Loans | Payment Deferral
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	13	2
Post-Modification Outstanding Recorded Investment	$ 0.8	$ 0.2
Home equity | Retail Loans | Combination of Concessions
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	39	29
Post-Modification Outstanding Recorded Investment	$ 2.4	$ 4
Home equity | Retail Loans | Bankruptcy
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	13	19
Post-Modification Outstanding Recorded Investment	$ 1.4	$ 1.5
Other consumer | Retail Loans
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0	$ 0

Loans - Summary of Recorded I_2

Loans - Summary of Recorded Investments in TDRs by Class of Loan, Subsequently Defaulted (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)contract	Dec. 31, 2020USD ($)contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	23	21
Recorded Investment | $	$ 4.7	$ 8
Commercial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	9	19
Recorded Investment | $	$ 1.5	$ 7.9
Commercial | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	0	2
Recorded Investment | $	$ 0	$ 1.5
Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	1	8
Recorded Investment | $	$ 1.2	$ 4.7
Commercial | Equipment financing
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	8	9
Recorded Investment | $	$ 0.3	$ 1.7
Commercial | MW/ABL
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	0	0
Recorded Investment | $	$ 0	$ 0
Retail Loans
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	14	2
Recorded Investment | $	$ 3.2	$ 0.1
Retail Loans | Residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	6	2
Recorded Investment | $	$ 2.8	$ 0.1
Retail Loans | Home equity
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	8	0
Recorded Investment | $	$ 0.4	$ 0
Retail Loans | Other consumer
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	0	0
Recorded Investment | $	$ 0	$ 0

Loans - Schedule of Commercial

Loans - Schedule of Commercial Loans by Risk Rating (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 37,851.3	$ 43,869.5
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	29,131.9	33,249.2
Commercial | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	530	889
Originated in fiscal year before current fiscal year	1,001.5	1,842.8
Originated two years before current fiscal year	1,937.6	1,779.3
Originated three years before current fiscal year	1,457.2	1,580.9
Originated four years before current fiscal year	1,193.2	1,396.3
Prior	5,646.1	5,655.6
Revolving Loans	137.6	169.1
Revolving Loans Converted to Term	33.5	23.9
Loans	11,936.7	13,336.9
Commercial | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	508.3	848.5
Originated in fiscal year before current fiscal year	916.4	1,743.2
Originated two years before current fiscal year	1,701	1,490.4
Originated three years before current fiscal year	1,177.7	1,397.8
Originated four years before current fiscal year	968.2	1,274.2
Prior	4,796.2	5,039.3
Revolving Loans	136.1	165.8
Revolving Loans Converted to Term	32.9	19.7
Loans	10,236.8	11,978.9
Commercial | Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	18.4	28.5
Originated in fiscal year before current fiscal year	73.8	72.9
Originated two years before current fiscal year	124.1	225.6
Originated three years before current fiscal year	129.7	131.2
Originated four years before current fiscal year	118.4	58.9
Prior	342.7	362.7
Revolving Loans	0	0.5
Revolving Loans Converted to Term	0.4	0
Loans	807.5	880.3
Commercial | Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	3.3	12
Originated in fiscal year before current fiscal year	11.3	26.7
Originated two years before current fiscal year	112.5	63.3
Originated three years before current fiscal year	149.7	51.9
Originated four years before current fiscal year	106.6	63.2
Prior	506.2	252.7
Revolving Loans	1.5	2.8
Revolving Loans Converted to Term	0.2	4.2
Loans	891.3	476.8
Commercial | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	0
Originated two years before current fiscal year	0	0
Originated three years before current fiscal year	0.1	0
Originated four years before current fiscal year	0	0
Prior	1	0.9
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	1.1	0.9
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	1,659.9	3,093.7
Originated in fiscal year before current fiscal year	676.7	1,364.9
Originated two years before current fiscal year	894.6	952.5
Originated three years before current fiscal year	580.1	695
Originated four years before current fiscal year	573.1	574.9
Prior	1,734.2	1,853.3
Revolving Loans	2,554.7	2,127.6
Revolving Loans Converted to Term	74.3	102.2
Loans	8,747.6	10,764.1
Commercial | Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	1,646.7	2,952.8
Originated in fiscal year before current fiscal year	656.3	1,236.9
Originated two years before current fiscal year	834.3	821.9
Originated three years before current fiscal year	538.7	527.1
Originated four years before current fiscal year	445.9	487.2
Prior	1,517.6	1,588.5
Revolving Loans	2,475.4	1,949.1
Revolving Loans Converted to Term	47	77.4
Loans	8,161.9	9,640.9
Commercial | Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	2.2	113.9
Originated in fiscal year before current fiscal year	2.9	41.7
Originated two years before current fiscal year	19.3	46.4
Originated three years before current fiscal year	10.9	120.3
Originated four years before current fiscal year	41.5	57.1
Prior	81.6	122.1
Revolving Loans	24.7	80.8
Revolving Loans Converted to Term	8.4	6.3
Loans	191.5	588.6
Commercial | Commercial and industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	11	27
Originated in fiscal year before current fiscal year	17.5	86.3
Originated two years before current fiscal year	40.7	84.2
Originated three years before current fiscal year	30.5	47.6
Originated four years before current fiscal year	85.7	29.8
Prior	134.5	141.2
Revolving Loans	54.6	97.7
Revolving Loans Converted to Term	18.9	18.4
Loans	393.4	532.2
Commercial | Commercial and industrial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	0
Originated two years before current fiscal year	0.3	0
Originated three years before current fiscal year	0	0
Originated four years before current fiscal year	0	0.8
Prior	0.5	1.5
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0.1
Loans	0.8	2.4
Commercial | Equipment financing
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	2,183.2	1,893.7
Originated in fiscal year before current fiscal year	1,270.3	1,523.7
Originated two years before current fiscal year	956.5	831.6
Originated three years before current fiscal year	444.9	419.2
Originated four years before current fiscal year	192.8	177.6
Prior	95.4	84.2
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	5,143.1	4,930
Commercial | Equipment financing | Pass
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	2,005.1	1,703.3
Originated in fiscal year before current fiscal year	1,151.2	1,358.7
Originated two years before current fiscal year	847.7	727.2
Originated three years before current fiscal year	390.6	362.1
Originated four years before current fiscal year	157.7	155.5
Prior	78.5	67.1
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	4,630.8	4,373.9
Commercial | Equipment financing | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	27.5	20.5
Originated in fiscal year before current fiscal year	8.4	27.5
Originated two years before current fiscal year	14.4	16.7
Originated three years before current fiscal year	5.9	7.3
Originated four years before current fiscal year	8	4.2
Prior	2.5	1.5
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	66.7	77.7
Commercial | Equipment financing | Substandard
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	150.6	169.9
Originated in fiscal year before current fiscal year	110.7	137.5
Originated two years before current fiscal year	94.4	87.7
Originated three years before current fiscal year	48.4	49.8
Originated four years before current fiscal year	27.1	17.9
Prior	14.4	15.6
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	445.6	478.4
Commercial | Equipment financing | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	0
Originated two years before current fiscal year	0	0
Originated three years before current fiscal year	0	0
Originated four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	0	0
Commercial | MW/ABL
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	44.7	99.4
Originated in fiscal year before current fiscal year	13.8	27.2
Originated two years before current fiscal year	15	18.3
Originated three years before current fiscal year	10.2	8.8
Originated four years before current fiscal year	3.1	14.1
Prior	25.7	19.6
Revolving Loans	3,191.2	4,029.8
Revolving Loans Converted to Term	0.8	1
Loans	3,304.5	4,218.2
Commercial | MW/ABL | Pass
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	44.7	99.4
Originated in fiscal year before current fiscal year	13.8	18.6
Originated two years before current fiscal year	15	18.3
Originated three years before current fiscal year	10.2	8.8
Originated four years before current fiscal year	3.1	14.1
Prior	25.7	19.6
Revolving Loans	3,147.8	3,994.3
Revolving Loans Converted to Term	0	0
Loans	3,260.3	4,173.1
Commercial | MW/ABL | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	6.9
Originated two years before current fiscal year	0	0
Originated three years before current fiscal year	0	0
Originated four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	12.6	20.5
Revolving Loans Converted to Term	0	0
Loans	12.6	27.4
Commercial | MW/ABL | Substandard
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	1.7
Originated two years before current fiscal year	0	0
Originated three years before current fiscal year	0	0
Originated four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	30.8	15
Revolving Loans Converted to Term	0.8	1
Loans	31.6	17.7
Commercial | MW/ABL | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	0
Originated two years before current fiscal year	0	0
Originated three years before current fiscal year	0	0
Originated four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	$ 0	$ 0

Loans - Summary of Retail Loans

Loans - Summary of Retail Loans by Risk Rating (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 37,851.3	$ 43,869.5
Retail Loans
Financing Receivable, Recorded Investment [Line Items]
Loans	8,719.4	10,620.3
Retail Loans | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	1,382.5	1,443.2
Originated in fiscal year before current fiscal year	1,299.3	866.3
Originated two years before current fiscal year	557.5	877.2
Originated three years before current fiscal year	480.7	1,131.1
Originated four years before current fiscal year	648	1,611.4
Prior	2,636.3	2,589.7
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	7,004.3	8,518.9
Retail Loans | Residential mortgage | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	753.4	609.5
Originated in fiscal year before current fiscal year	643	349.1
Originated two years before current fiscal year	277	338.3
Originated three years before current fiscal year	208.8	504
Originated four years before current fiscal year	321.4	1,004.6
Prior	1,922.9	1,793.8
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	4,126.5	4,599.3
Retail Loans | Residential mortgage | Moderate Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	567.1	752.5
Originated in fiscal year before current fiscal year	602.8	456.8
Originated two years before current fiscal year	243.7	443.9
Originated three years before current fiscal year	215.6	517.5
Originated four years before current fiscal year	253.3	520.2
Prior	463.1	519.8
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	2,345.6	3,210.7
Retail Loans | Residential mortgage | High Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	62	81.2
Originated in fiscal year before current fiscal year	53.5	60.4
Originated two years before current fiscal year	36.8	95
Originated three years before current fiscal year	56.3	109.6
Originated four years before current fiscal year	73.3	86.6
Prior	250.3	276.1
Revolving Loans	0	0
Revolving Loans Converted to Term	0	0
Loans	532.2	708.9
Retail Loans | Home equity
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	3.5	5.3
Originated in fiscal year before current fiscal year	3.8	32.9
Originated two years before current fiscal year	21.7	68.4
Originated three years before current fiscal year	45.1	58.8
Originated four years before current fiscal year	39.7	24.8
Prior	58.3	58
Revolving Loans	1,262.9	1,515.7
Revolving Loans Converted to Term	200.9	233.3
Loans	1,635.9	1,997.2
Retail Loans | Home equity | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	2.4	1.9
Originated in fiscal year before current fiscal year	2.4	7.4
Originated two years before current fiscal year	8.2	21.1
Originated three years before current fiscal year	24.2	24.6
Originated four years before current fiscal year	22.7	10.7
Prior	29.2	25.8
Revolving Loans	538.1	580
Revolving Loans Converted to Term	44.4	42.9
Loans	671.6	714.4
Retail Loans | Home equity | Moderate Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0.7	0.6
Originated in fiscal year before current fiscal year	0.8	3.7
Originated two years before current fiscal year	4.1	9.2
Originated three years before current fiscal year	12	12.2
Originated four years before current fiscal year	11.6	6.6
Prior	15.5	13.4
Revolving Loans	416.4	520
Revolving Loans Converted to Term	43.3	45.3
Loans	504.4	611
Retail Loans | Home equity | High Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0.4	2.8
Originated in fiscal year before current fiscal year	0.6	21.8
Originated two years before current fiscal year	9.4	38.1
Originated three years before current fiscal year	8.9	22
Originated four years before current fiscal year	5.4	7.5
Prior	13.6	18.8
Revolving Loans	308.4	415.7
Revolving Loans Converted to Term	113.2	145.1
Loans	459.9	671.8
Retail Loans | Other consumer
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	5.9	6.4
Originated in fiscal year before current fiscal year	2.9	29
Originated two years before current fiscal year	13.2	19.6
Originated three years before current fiscal year	8.3	3.2
Originated four years before current fiscal year	1.5	1.4
Prior	7.7	11.3
Revolving Loans	37.5	33
Revolving Loans Converted to Term	2.2	0.3
Loans	79.2	104.2
Retail Loans | Other consumer | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	1.2	0.9
Originated in fiscal year before current fiscal year	0.5	1.7
Originated two years before current fiscal year	1.4	1.7
Originated three years before current fiscal year	1.3	0.9
Originated four years before current fiscal year	0.8	0.4
Prior	2.6	2.7
Revolving Loans	18	11.4
Revolving Loans Converted to Term	1.2	0.1
Loans	27	19.8
Retail Loans | Other consumer | Moderate Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	0	0
Originated in fiscal year before current fiscal year	0	0
Originated two years before current fiscal year	0	0
Originated three years before current fiscal year	0	0
Originated four years before current fiscal year	0	0
Prior	0	0.1
Revolving Loans	4	4.8
Revolving Loans Converted to Term	0.1	0.1
Loans	4.1	5
Retail Loans | Other consumer | High Risk
Financing Receivable, Recorded Investment [Line Items]
Originated in current fiscal year	4.7	5.5
Originated in fiscal year before current fiscal year	2.4	27.3
Originated two years before current fiscal year	11.8	17.9
Originated three years before current fiscal year	7	2.3
Originated four years before current fiscal year	0.7	1
Prior	5.1	8.5
Revolving Loans	15.5	16.8
Revolving Loans Converted to Term	0.9	0.1
Loans	$ 48.1	$ 79.4

Loans - Summary of Credit Quali

Loans - Summary of Credit Quality Indicators by Class of Loan (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 37,851.3	$ 43,869.5
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	29,131.9	33,249.2
Retail Loans
Financing Receivable, Recorded Investment [Line Items]
Loans	8,719.4	10,620.3
Commercial real estate | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	11,936.7	13,336.9
Commercial real estate | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	10,236.8	11,978.9
Commercial real estate | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	807.5	880.3
Commercial real estate | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	891.3	476.8
Commercial real estate | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1.1	0.9
Commercial and industrial | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	8,747.6	10,764.1
Commercial and industrial | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	8,161.9	9,640.9
Commercial and industrial | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	191.5	588.6
Commercial and industrial | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	393.4	532.2
Commercial and industrial | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0.8	2.4
Equipment financing | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	5,143.1	4,930
Equipment financing | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	4,630.8	4,373.9
Equipment financing | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	66.7	77.7
Equipment financing | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	445.6	478.4
Equipment financing | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Residential mortgage | Retail Loans
Financing Receivable, Recorded Investment [Line Items]
Loans	7,004.3	8,518.9
Residential mortgage | Retail Loans | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	4,126.5	4,599.3
Residential mortgage | Retail Loans | Moderate Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	2,345.6	3,210.7
Residential mortgage | Retail Loans | High Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	532.2	708.9
Home equity | Retail Loans
Financing Receivable, Recorded Investment [Line Items]
Loans	1,635.9	1,997.2
Home equity | Retail Loans | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	671.6	714.4
Home equity | Retail Loans | Moderate Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	504.4	611
Home equity | Retail Loans | High Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	459.9	671.8
Other consumer | Retail Loans
Financing Receivable, Recorded Investment [Line Items]
Loans	79.2	104.2
Other consumer | Retail Loans | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	27	19.8
Other consumer | Retail Loans | Moderate Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	4.1	5
Other consumer | Retail Loans | High Risk
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 48.1	$ 79.4

Loans - Revolving Loans Convert

Loans - Revolving Loans Converted to Term (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	$ 80.9	$ 91.9
Commercial
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	40.4	54.7
Commercial | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	15.3	1.4
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	25.1	53.3
Commercial | Equipment financing
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	0	0
Commercial | MW/ABL
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	0	0
Retail Loans
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	40.5	37.2
Retail Loans | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	0	0
Retail Loans | Home equity
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	39.3	37.1
Retail Loans | Other consumer
Financing Receivable, Recorded Investment [Line Items]
Revolving loans converted to term loan	$ 1.2	$ 0.1

Allowance For Credit Losses (De

Allowance For Credit Losses (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Allowance for Credit Loss [Abstract]
Financing receivable, allowance for credit losses, collectively evaluated for impairment	$ 330	$ 404.6
Financing receivable, allowance for credit losses, individually evaluated for impairment	$ 13.6	$ 20.5

Allowance for Credit Losses - S

Allowance for Credit Losses - Schedule of Allowance For Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 425.1	$ 246.6	$ 240.4
Charge-offs	(51.4)	(58.9)	(31.5)
Recoveries	18.1	9.1	9.4
Net loan charge-offs	(33.3)	(49.8)	(22.1)
Provision for credit losses on loans	(48.2)	156.1	28.3
Balance at end of period	343.6	425.1	246.6
Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	303.6	217.9	209.5
Charge-offs	(48.3)	(52.4)	(27.5)
Recoveries	12.8	6.4	6.3
Net loan charge-offs	(35.5)	(46)	(21.2)
Provision for credit losses on loans	(66.5)	149	29.6
Balance at end of period	201.6	303.6	217.9
Retail Loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	121.5	28.7	30.9
Charge-offs	(3.1)	(6.5)	(4)
Recoveries	5.3	2.7	3.1
Net loan charge-offs	2.2	(3.8)	(0.9)
Provision for credit losses on loans	18.3	7.1	(1.3)
Balance at end of period	$ 142	121.5	28.7
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		72.2
Balance at end of period			72.2
Cumulative Effect, Period of Adoption, Adjustment | Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		(17.3)
Balance at end of period			(17.3)
Cumulative Effect, Period of Adoption, Adjustment | Retail Loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		89.5
Balance at end of period			89.5
Cumulative Effect, Period of Adoption, Adjusted Balance
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		318.8
Balance at end of period			318.8
Cumulative Effect, Period of Adoption, Adjusted Balance | Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		200.6
Balance at end of period			200.6
Cumulative Effect, Period of Adoption, Adjusted Balance | Retail Loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		$ 118.2
Balance at end of period			$ 118.2

Allowance For Credit Losses - O

Allowance For Credit Losses - Off-Balance Sheet (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 26.9	$ 5.6	$ 2.7
Provision charged (credited) to income	1.5	6.8	2.9
Balance at end of period	$ 28.4	26.9	5.6
Cumulative Effect, Period of Adoption, Adjustment
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period		14.5
Balance at end of period			14.5
Cumulative Effect, Period of Adoption, Adjusted Balance
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period		$ 20.1
Balance at end of period			$ 20.1

Leases - Net Investment in Leas

Leases - Net Investment in Lease Financing Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Lease payments receivable	$ 1,368.3	$ 1,418.4
Estimated residual value of leased assets	130.1	132.7
Gross investment in lease financing receivables	1,498.4	1,551.1
Plus: Deferred origination costs	10.2	11.6
Less: Unearned income	(140.4)	(150.7)
Total net investment in lease financing receivables	$ 1,368.2	$ 1,412

Leases - Contractual Maturities

Leases - Contractual Maturities of Lease Financing Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2022	$ 532.9
2023	402.6
2024	292
2025	172.3
2026	83
Later years	15.6
Gross investment in lease financing receivables	$ 1,498.4	$ 1,551.1

Leases - Schedule of Lease Inco

Leases - Schedule of Lease Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Lease financing receivables	$ 66.3	$ 69	$ 66.7
Operating leases	44.7	49.7	50.8
Total lease income	$ 111	$ 118.7	$ 117.5

Leases - Components of Lease Co

Leases - Components of Lease Cost and Supplemental Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 63	$ 65.1	$ 61.6
Variable lease cost	9.8	10	8.6
Finance lease cost	0.3	0.3	0.1
Sublease income	(2.2)	(1.9)	(1.4)
Net lease cost	$ 70.9	$ 73.5	68.9
Lease ROU assets:
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets	Other Assets
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets	Other Assets
Operating lease	$ 210.6	$ 234.9
Finance lease	$ 2.1	$ 2.3
Lease liabilities:
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Operating lease	$ 242	$ 270.4
Finance lease	$ 4.5	$ 4.9
Weighted-average discount rate:
Operating leases	2.86%	3.08%
Finance leases	2.59%	2.59%
Weighted-average remaining lease term (in years):
Operating leases	7 years 2 months 12 days	7 years 7 months 6 days
Finance leases	10 years 3 months 18 days	11 years 2 months 12 days
Cash payments included in the measurement of lease liabilities:
Reported in operating cash from operating leases	$ 68.6	$ 66.6	61.7
Reported in financing cash from finance leases	0.1	0.1	0.1
ROU assets obtained in exchange for lessee:
Operating lease liabilities	31.4	22.8	89.1
Finance lease liabilities	$ 0	$ 0	$ 2.6

Leases - Contractual Maturiti_2

Leases - Contractual Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Operating Leases
2022	$ 55.6
2023	44.2
2024	38.8
2025	34.7
2026	24.5
Later years	74.1
Total lease payments	271.9
Less: Interest	(29.9)
Operating lease	242	$ 270.4
Finance Leases
2022	0.5
2023	0.5
2024	0.5
2025	0.5
2026	0.5
Later years	2.6
Total lease payments	5.1
Less: Interest	(0.6)
Finance lease	$ 4.5	$ 4.9

Leases - Additional Information

Leases - Additional Information (Details) $ in Millions	3 Months Ended
	Sep. 30, 2021USD ($)saleLeaseback	Dec. 31, 2019USD ($)
Leases [Abstract]
Number of sale-leaseback transactions | saleLeaseback	2
Gain on sale leaseback transaction | $	$ 3.9	$ 3.3

Goodwill and Other Acquisitio_3

Goodwill and Other Acquisition-Related Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Millions	Oct. 01, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance		$ 2,680.8	$ 3,065.5
Write-down relating to the sale of branches			(31.7)
Goodwill impairment	$ (353)	0	(353)	$ 0
Ending balance		2,680.8	2,680.8	3,065.5
Commercial Banking
Goodwill [Roll Forward]
Beginning balance		1,966.1	1,966.1
Write-down relating to the sale of branches			0
Goodwill impairment			0
Ending balance		1,966.1	1,966.1	1,966.1
Retail Banking
Goodwill [Roll Forward]
Beginning balance		657.9	1,010.9
Write-down relating to the sale of branches			0
Goodwill impairment			(353)
Ending balance		657.9	657.9	1,010.9
Wealth Management
Goodwill [Roll Forward]
Beginning balance		56.8	88.5
Write-down relating to the sale of branches			(31.7)
Goodwill impairment			0
Ending balance		$ 56.8	$ 56.8	$ 88.5

Goodwill and Other Acquisitio_4

Goodwill and Other Acquisition-Related Intangible Assets - Additional Information (Detail)	Oct. 01, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2021USD ($)Reporting_Unit	Dec. 31, 2020USD ($)Reporting_Unit	Dec. 31, 2019USD ($)Reporting_Unit	Oct. 25, 2019branch
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment (note 8)	$ 353,000,000			$ 0	$ 353,000,000	$ 0
Impairment percent of total goodwill	12.00%
Number of reporting units | Reporting_Unit				3	3	3
Goodwill expected to be tax deductible		$ 113,600,000		$ 103,400,000	$ 113,600,000
Weighted-average amortization period				12 years
Amortization of other acquisition-related intangible assets				$ 37,000,000	40,800,000	$ 32,500,000
Amortization expense attributable to other acquisition-related intangible assets, 2021				30,900,000
Amortization expense attributable to other acquisition-related intangible assets, 2022				23,200,000
Amortization expense attributable to other acquisition-related intangible assets, 2023				19,500,000
Amortization expense attributable to other acquisition-related intangible assets, 2024				16,700,000
Amortization expense attributable to other acquisition-related intangible assets, 2025				13,800,000
Impairment losses relating to goodwill or other acquisition-related intangible assets				$ 0	0	$ 0
Commercial Banking
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment (note 8)					0
Percentage of fair value in excess of carrying amount	4.00%
Wealth Management
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment (note 8)					$ 0
Percentage of fair value in excess of carrying amount	103.00%
Valuation Technique, Discounted Cash Flow
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment assessment, weighted percent	75.00%
Valuation, Market Approach
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment assessment, weighted percent	25.00%
Central Maine Branch Sale
Acquired Finite-Lived Intangible Assets [Line Items]
Number of branches sold | branch							8
Trust relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset write-down		$ 3,200,000	$ 1,000,000
Mutual Fund Management Contract
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset write-down			16,500,000
Trade name intangible
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible asset write-down			$ 1,900,000

Goodwill and Other Acquisitio_5

Goodwill and Other Acquisition-Related Intangible Assets - Other Acquisition-Related Intangibles (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 536.5	$ 536.5
Accumulated Amortization	408.7	371.4
Carrying Amount	127.8	165.1
Core deposit intangible
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	303.9	303.9
Accumulated Amortization	230.9	206.3
Carrying Amount	73	97.6
Trade name intangible
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	123.9	123.9
Accumulated Amortization	85.5	79.6
Carrying Amount	38.4	44.3
Client relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	24.4	24.4
Accumulated Amortization	10.5	8.4
Carrying Amount	13.9	16
Trust relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	42.7	42.7
Accumulated Amortization	40.2	37.6
Carrying Amount	2.5	5.1
Insurance relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	38.1	38.1
Accumulated Amortization	38.1	38.1
Carrying Amount	0	0
Favorable lease agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	2.9	2.9
Accumulated Amortization	2.9	0.9
Carrying Amount	0	2
Non-compete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Amount	0.6	0.6
Accumulated Amortization	0.6	0.5
Carrying Amount	$ 0	$ 0.1

Premises and Equipment - Compon

Premises and Equipment - Components of Premises and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Land	$ 48	$ 51.1
Buildings	303.5	313.6
Leasehold improvements	166.5	169.6
Furniture and equipment	280.7	277.3
Total	798.7	811.6
Less: Accumulated depreciation and amortization	556.9	534.9
Total premises and equipment, net	$ 241.8	$ 276.7

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense included in occupancy and equipment expense	$ 44	$ 43.4	$ 41.7

Other Assets and Other Liabil_3

Other Assets and Other Liabilities - Components of Other Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Other Assets [Line Items]
Affordable housing investments	$ 588.3	$ 460.8
Fair value of derivative financial instruments (notes 21 and 23)	388.1	800.3
Funded status of defined benefit pension plans	256.4	141.2
Lease ROU assets	212.7	237.2
Accrued interest receivable (notes 4 and 5)	167.2	202.2
Leased equipment	118.3	163.7
Assets held in trust for supplemental retirement plans	94.5	56.9
Net deferred tax asset	63.5	45.8
Economic development investments	33.8	29.1
Other prepaid expenses	26.5	32.7
Current income tax receivable	18.6	44.7
Investment in joint venture	14.4	14.7
Loan disbursements in process	7.1	68
Mortgage servicing rights	4.3	4.8
Repossessed assets	3.7	5.7
Other	26.6	37.6
Total other assets	2,025.4	2,352.2
Commercial real estate
Schedule Of Other Assets [Line Items]
REO	0	3.6
Residential mortgage
Schedule Of Other Assets [Line Items]
REO	$ 1.4	$ 3.2

Other Assets and Other Liabil_4

Other Assets and Other Liabilities - Components of Other Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Assets And Other Liabilities [Abstract]
Future contingent commitments for affordable housing investments	$ 264.5	$ 182.4
Lease liabilities	246.5	275.3
Fair value of derivative financial instruments (notes 21 and 23)	95.3	170.4
Accrued expenses payable	92.8	82.6
Accrued employee benefits	90.3	72.2
Liabilities for supplemental retirement plans	86.8	89.5
Liability for unsettled purchases of securities	45.5	194.8
Reserve for uncertain tax positions	32.4	33.4
ACL on off-balance-sheet credit exposures (note 6)	28.4	26.9	$ 5.6	$ 2.7
Other postretirement plans	16.5	17.7
Accrued interest payable	11	12.1
Loan payments in process	0	28.3
Other	24.7	8.5
Total other liabilities	$ 1,034.7	$ 1,194.1

Deposits - Schedule of Deposits

Deposits - Schedule of Deposits (Detail) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Amount
Non-interest-bearing	$ 17,941,100,000	$ 15,881,700,000
Savings	6,733,700,000	6,029,700,000
Interest-bearing checking and money market	25,383,800,000	24,567,500,000
Time deposits maturing:
Within 3 months	1,444,200,000	1,850,600,000
After 3 but within 6 months	836,700,000	1,155,100,000
After 6 months but within 1 year	807,700,000	1,464,100,000
After 1 but within 2 years	447,600,000	950,800,000
After 2 but within 3 years	76,200,000	165,700,000
After 3 but within 4 years	50,600,000	18,100,000
After 4 but within 5 years	33,700,000	54,400,000
After 5 years (less than $0.1 million)	0	0
Total	3,696,700,000	5,658,800,000
Total deposits	$ 53,755,300,000	$ 52,137,700,000
Weighted- Average Rate
Non-interest-bearing	0.00%	0.00%
Savings	0.02%	0.04%
Interest-bearing checking and money market	0.12%	0.17%
Time deposits maturing:
Within 3 months	0.57%	1.10%
After 3 but within 6 months	0.25%	0.68%
After 6 months but within 1 year	0.20%	0.75%
After 1 but within 2 years	0.73%	1.02%
After 2 but within 3 years	0.43%	1.75%
After 3 but within 4 years	0.67%	0.99%
After 4 but within 5 years	0.33%	0.68%
After 5 years	0.00%	0.99%
Total	0.43%	0.92%
Total deposits	0.09%	0.19%
Maximum
Time deposits maturing:
After 5 years (less than $0.1 million)	$ 0	$ 100,000

Deposits - Additional Informati

Deposits - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financial Services Costs [Abstract]
Time deposits issued in amounts that exceed $250,000	$ 771.8	$ 1,200
Non-interest-bearing deposit overdrafts	$ 2.8	$ 2.8

Deposits - Schedule of Interest

Deposits - Schedule of Interest Expense on Deposits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financial Services Costs [Abstract]
Savings	$ 2	$ 5.4	$ 13.4
Interest-bearing checking and money market	38.4	86.8	195.9
Time	28.3	95	147.6
Total	$ 68.7	$ 187.2	$ 356.9

Borrowings - Summary of Borrowi

Borrowings - Summary of Borrowings (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fixed-rate FHLB advances maturing:
After 1 month but within 1 year	$ 551.2	$ 556.9
After 1 but within 2 years	0.5	1.2
After 2 but within 3 years	0	0.5
After 3 but within 4 years	8.5	0
After 4 but within 5 years	0.7	8.6
After 5 years	1.7	2.5
Total FHLB advances	562.6	569.7	$ 3,125.4
Federal funds purchased maturing:
Within 1 month	0	125
Total federal funds purchased	0	125	1,620
Customer repurchase agreements maturing:
Within 1 month	395.2	452.9
Total customer repurchase agreements	395.2	452.9	$ 409.1
Total borrowings	$ 957.8	$ 1,147.6
Fixed-rate FHLB advances maturing, weighted average rate
After 1 month but within 1 year	0.37%	0.41%
After 1 but within 2 years	0.05%	0.50%
After 2 but within 3 years	0.00%	0.05%
After 3 but within 4 years	1.70%	0.00%
After 4 but within 5 years	0.57%	1.70%
After 5 years	0.92%	0.83%
Total FHLB advances	0.39%	0.43%
Federal funds purchased maturing, weighted average rate
Within 1 month	0.00%	0.07%
Total federal funds purchased	0.00%	0.07%
Customer repurchase agreements maturing:
Within 1 month	0.10%	0.14%
Total customer repurchase agreements	0.10%	0.14%
Total borrowings, weighted average rate	0.27%	0.28%

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) $ in Billions	Dec. 31, 2021USD ($)
Debt Disclosure [Abstract]
Repurchase agreements and advances borrowing limit	$ 11.8
Unsecured borrowing capacity	$ 1

Borrowings - Interest Expense o

Borrowings - Interest Expense on Borrowings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
FHLB advances	$ 4.3	$ 13.7	$ 50.1
Federal funds purchased	0	5.4	24.6
Customer repurchase agreements	0.4	1.1	2.2
Other borrowings	0	0	0.1
Total	$ 4.7	$ 20.2	$ 77

Borrowings - Information Concer

Borrowings - Information Concerning Parent Company Borrowings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
FHLB advances:
Balance at year end	$ 562.6	$ 569.7	$ 3,125.4
Average outstanding during the year	569.6	1,371.2	2,098
Maximum outstanding at any month end	$ 569.7	$ 4,489.7	$ 3,125.5
Average interest rate during the year	0.75%	1.00%	2.39%
Federal funds purchased:
Balance at year end	$ 0	$ 125	$ 1,620
Average outstanding during the year	52.8	688.2	1,127.5
Maximum outstanding at any month end	$ 150	$ 1,692	$ 1,665
Average interest rate during the year	0.09%	0.79%	2.18%
Customer repurchase agreements:
Balance at year end	$ 395.2	$ 452.9	$ 409.1
Average outstanding during the year	394.3	379	296.6
Maximum outstanding at any month end	$ 436.2	$ 452.9	$ 409.1
Average interest rate during the year	0.11%	0.29%	0.75%
Other borrowings:
Balance at year end	$ 0	$ 0	$ 0
Average outstanding during the year	0	0	3.3
Maximum outstanding at any month end	$ 0	$ 0	$ 10.4
Average interest rate during the year	0.00%	0.00%	1.87%
Securities Sold under Agreements to Repurchase
Customer repurchase agreements:
Carrying amount of collateral securities at year end	$ 403.1	$ 462	$ 418

Notes and Debentures - Schedule

Notes and Debentures - Schedule of Subordinated Borrowing (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Subordinated Borrowing [Line Items]
Total notes and debentures	$ 992.8	$ 1,009.6
4.00% Subordinated Notes Due 2024
Subordinated Borrowing [Line Items]
Interest rate on debt	4.00%
People's United Financial, Inc.
Subordinated Borrowing [Line Items]
Total notes and debentures	$ 578.4	579.1
People's United Financial, Inc. | 3.65% Senior Notes Due 2022
Subordinated Borrowing [Line Items]
Debt instrument interest rate	3.65%
Senior notes	$ 499.6	498.9
People's United Financial, Inc. | 5.75% Subordinated Notes Due 2024
Subordinated Borrowing [Line Items]
Interest rate on debt	5.75%
Subordinated notes	$ 78.8	80.2
People's United Bank | 4.00% Subordinated Notes Due 2024
Subordinated Borrowing [Line Items]
Subordinated notes	$ 414.4	$ 430.5

Notes and Debentures - Addition

Notes and Debentures - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021
Subordinated Borrowing [Line Items]
Debt instrument, maturity date	Apr. 16, 2024
4.00% Subordinated Notes Due 2024
Subordinated Borrowing [Line Items]
Interest rate on debt	4.00%
People's United Financial, Inc. | 3.65% Senior Notes Due 2022
Subordinated Borrowing [Line Items]
Debt instrument interest rate	3.65%
Debt instrument call option date	Sep. 6, 2022
Percentage of redemption price to principal amount	100.00%
People's United Financial, Inc. | 5.75% Subordinated Notes Due 2024
Subordinated Borrowing [Line Items]
Interest rate on debt	5.75%
People's United Bank | 4.00% Subordinated Notes Due 2024
Subordinated Borrowing [Line Items]
Percentage of redemption price to principal amount	100.00%
Number of days excluded for redemption of principal amount on occurrence of a regulatory event	90 days

Income Taxes - Summary of Total

Income Taxes - Summary of Total Income Tax Expense (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax expense applicable to pre-tax income	$ 40	$ 29.7	$ 44.9	$ 37.7	$ 45.2	$ 27.5	$ 20.5	$ 35.8	$ 152.3	$ 129	$ 132
Deferred income tax (benefit) expense applicable to items reported in total other comprehensive income (loss)									(16.5)	24.1	27.2
Total									$ 135.8	$ 153.1	$ 159.2

Income Taxes - Income Tax Effec

Income Taxes - Income Tax Effects Related to Items Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal									$ 116	$ 113.4	$ 90.8
State									33.7	34.3	26.9
Total current tax expense									149.7	147.7	117.7
Deferred tax expense (benefit)									2.6	(18.7)	14.3
Total income tax expense	$ 40	$ 29.7	$ 44.9	$ 37.7	$ 45.2	$ 27.5	$ 20.5	$ 35.8	152.3	129	132
Increase (decrease) in valuation allowance for state deferred tax assets									$ (6.2)	$ (13.7)	$ (7.7)

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amount
Expected income tax expense									$ 159	$ 73.2	$ 137
State income tax, net of federal tax effect									27.1	23.9	22.6
Non-deductible FDIC insurance premiums									4.8	5.8	4.4
Tax-exempt interest									(22.7)	(22)	(21.4)
Federal income tax credits									(14.8)	(14.8)	(12.7)
Tax-exempt income from BOLI									(2.4)	(2.7)	(2.2)
Equity-based compensation									(0.5)	1.3	(0.1)
Release of CT valuation allowance	$ (7.1)								0	(7.1)	0
Non-deductible goodwill impairment									0	74.1	0
Other, net									1.8	(2.7)	4.4
Total income tax expense	$ 40	$ 29.7	$ 44.9	$ 37.7	$ 45.2	$ 27.5	$ 20.5	$ 35.8	$ 152.3	$ 129	$ 132
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Expected income tax expense									21.00%	21.00%	21.00%
State income tax, net of federal tax effect									3.60%	6.80%	3.40%
Non-deductible FDIC insurance premiums									0.60%	1.60%	0.70%
Tax-exempt interest									(3.00%)	(6.30%)	(3.30%)
Federal income tax credits									(1.90%)	(4.20%)	(2.00%)
Tax-exempt income from BOLI									(0.30%)	(0.80%)	(0.30%)
Equity-based compensation									(0.10%)	0.40%	0.00%
Release of CT valuation allowance									0.00%	(2.10%)	0.00%
Non-deductible goodwill impairment									0.00%	21.30%	0.00%
Other, net									0.20%	(0.70%)	0.70%
Effective income tax rate									20.10%	37.00%	20.20%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)fundmobileSolarUnit	Dec. 31, 2019USD ($)
Schedule Of Income Tax Expense [Line Items]
Affordable housing investments	$ 588.3	$ 588.3	$ 460.8
Future contingent commitments	264.5	$ 264.5	182.4
Amortization period		10 years
Income tax expense		$ 38.9	$ 31.4	$ 25
Number of tax advantage funds | fund			3
Number of mobile solar generators to be acquired under limited liability company | mobileSolarUnit			500
Connecticut tax net operating loss carryforwards	1,000	1,000
Adjustment of state net deferred tax assets	7.1	0	$ 7.1	0
Current income tax receivable	18.6	18.6	44.7
Accrued interest expense related to the unrecognized income tax benefits	$ 0.1	0.1	0.1
People's United Financial, Inc. | D.C. Solar investment
Schedule Of Income Tax Expense [Line Items]
Write down of investment				8.4
Additions related to D.C. Solar		$ 0	$ 0	$ 18.9

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Allowance for credit losses and non-accrual interest	$ 96.2	$ 117.3
State tax net operating loss carryforwards, net of federal tax effect	59.6	65.9
Tax credits and net operating loss carryforwards	24.7	24.7
Equity-based compensation	20.3	19.9
Acquisition-related deferred tax assets	12.8	12.7
ROU lease assets, net of lease liabilities	7.6	8.6
D.C. Solar investment basis difference	6.8	6.8
Unrealized loss on debt securities available-for-sale	6.3	0
Unrealized loss on debt securities transferred to held-to-maturity	1.4	2.5
Other deductible temporary differences	33.3	26.6
Total deferred tax assets	269	285
Less: valuation allowance for state deferred tax assets	(52.5)	(58.7)
Total deferred tax assets, net of the valuation allowance	216.5	226.3
Deferred tax liabilities:
Leasing activities	(69.3)	(88.3)
Unrealized gain on debt securities available-for-sale	0	(31.4)
Pension and other postretirement benefits	(57.3)	(25.6)
Book over tax income recognized on consumer loans	(17.2)	(17.2)
Temporary differences related to merchant services joint venture	(3.3)	(3.5)
Mark-to-market and original issue discounts for tax purposes	(3.7)	(1.8)
Other taxable temporary differences	(2.2)	(12.7)
Total deferred tax liabilities	(153)	(180.5)
Net deferred tax asset	$ 63.5	$ 45.8

Income Taxes - Unrecognized Inc

Income Taxes - Unrecognized Income Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 33.4	$ 33.3	$ 5.2
Additions for tax positions taken in prior years	0	0.1	0.5
Reductions attributable to audit settlements/lapse of statute of limitations	(1)	0	0
Balance at end of year	32.4	33.4	33.3
United Financial | D.C. Solar investment
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Additions related to D.C. Solar	0	0	8.7
People's United Financial, Inc. | D.C. Solar investment
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Additions related to D.C. Solar	$ 0	$ 0	$ 18.9

Stockholders' Equity and Divi_2

Stockholders' Equity and Dividends - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Apr. 30, 2007
Schedule Of Stockholders Equity [Line Items]
Preferred stock, shares authorized (in shares)	50,000,000				50,000,000				50,000,000	50,000,000
Preferred stock, par value (in dollars per share)	$ 0.01				$ 0.01				$ 0.01	$ 0.01
Preferred stock, shares issued (in shares)	10,000,000				10,000,000				10,000,000	10,000,000
Common stock, shares authorized (in shares)	1,950,000,000				1,950,000,000				1,950,000,000	1,950,000,000
Common stock, par value (in dollars per share)	$ 0.01				$ 0.01				$ 0.01	$ 0.01
Common stock, shares issued (in shares)	536,900,000				533,700,000				536,900,000	533,700,000
Number of common stock purchased (in shares)	109,000,000				109,000,000				109,000,000	109,000,000
Shares authorized to be repurchased (in shares)							20,000,000
Treasury stock shares acquired (in shares)								19,800,000			200,000
Treasury stock acquired								$ 304.4		$ 304.4	$ 2.5
Original loan amount ESOP												$ 216.8
ESOP shares purchased in open market												10,500,000
Unallocated common stock of Employee Stock Ownership Plan (in shares)	5,226,787				5,600,000				5,226,787	5,600,000
Unallocated common stock of employee stock ownership plan	$ 108.4				$ 115.6				$ 108.4	$ 115.6
Cash dividends on common stock (in dollars per share)									$ 0.7275	$ 0.7175	$ 0.7075
Dividend payout ratio	52.90%	56.80%	46.20%	53.70%	(50.80%)	53.60%	87.40%	60.90%	52.10%	148.00%	54.30%
Repurchases Authorized by Board of Directors
Schedule Of Stockholders Equity [Line Items]
Number of common stock purchased (in shares)	106,400,000								106,400,000
2007 Recognition and Retention Plan
Schedule Of Stockholders Equity [Line Items]
Number of common stock purchased (in shares)	2,600,000								2,600,000
People's United Financial, Inc.
Schedule Of Stockholders Equity [Line Items]
Preferred stock, shares authorized (in shares)	50,000,000								50,000,000
Preferred stock, par value (in dollars per share)	$ 0.01								$ 0.01
Preferred stock, shares issued (in shares)	10,000,000								10,000,000
Common stock, shares authorized (in shares)	1,950,000,000								1,950,000,000
Common stock, par value (in dollars per share)	$ 0.01								$ 0.01
Common stock, shares issued (in shares)	536,900,000								536,900,000
People's United Financial, Inc. | Bank Subsidiary
Schedule Of Stockholders Equity [Line Items]
Cash dividends payable to parent company									$ 437	$ 498	$ 457
People's United Bank
Schedule Of Stockholders Equity [Line Items]
Retained net income under federal regulations									$ (60.8)
2014 Long-Term Incentive Plan | 2007 Recognition and Retention Plan
Schedule Of Stockholders Equity [Line Items]
Additional awards under RRP (in shares)	0								0

Regulatory Capital Requiremen_3

Regulatory Capital Requirements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 capital, Ratio, Minimum capital adequacy	4.50%
Capital conservation buffer	2.50%
Common Equity Tier 1 Capital, Ratio, Minimum Capital Adequacy including conservation buffer	7.00%
Risk-based capital tier 1, Ratio, Minimum capital adequacy	0.060
Risk-based capital tier 1, Ratio, Minimum capital adequacy including conservation buffer	8.50%
Total, Ratio, Minimum capital adequacy	0.080
Total, Ratio, Minimum capital adequacy including conservation buffer	10.50%
Leverage (core) capital, Ratio	0.040
Capital conservation buffer	2.50%
People's United Financial, Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 capital, Ratio, Minimum capital adequacy	7.00%	7.00%
Risk-based capital tier 1, Ratio, Minimum capital adequacy	0.085	0.085
Total, Ratio, Minimum capital adequacy	0.139	0.124
Leverage (core) capital, Ratio	0.085	0.083
Risk-weighted assets	$ 41,800,000,000	$ 45,100,000,000
People's United Financial, Inc. | 4.00% Subordinated Notes Due 2024
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Senior notes issuance	$ 75,000,000
Reduction percentage	20.00%
Reduction amount	$ 15,000,000
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 capital, Ratio, Minimum capital adequacy	7.00%	7.00%
Risk-based capital tier 1, Ratio, Minimum capital adequacy	0.085	0.085
Total, Ratio, Minimum capital adequacy	0.140	0.128
Leverage (core) capital, Ratio	0.086	0.087
Risk-weighted assets	$ 41,800,000,000	$ 45,000,000,000
Bank | 4.00% Subordinated Notes Due 2024
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Senior notes issuance	$ 400,000,000
Reduction percentage	20.00%
Reduction amount	$ 80,000,000

Regulatory Capital Requiremen_4

Regulatory Capital Requirements - Regulatory Capital Requirements and Ratio under Basel III Capital Rules (Detail) $ in Millions	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Leverage Capital, Ratio	0.040
Total, Ratio	0.080
CET 1 Risk-Based Capital, Ratio, Minimum Capital Required	4.50%
Tier 1 Risk-Based Capital, Ratio, Minimum Capital Required	0.060
Total Risk-Weighted Assets for allowance for loan losses	1.25%
People's United Financial, Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Leverage Capital, Amount	$ 5,326.7	$ 4,967.8
CET 1 Risk-Based Capital, Amount	5,082.6	4,723.7
Tier 1 Risk-Based Capital	5,326.7	4,967.8
Total, Amount	$ 5,793.3	$ 5,589.5
Tier 1 Leverage Capital, Ratio	0.085	0.083
CET 1 Risk-Based Capital, Ratio	12.20%	10.50%
Tier 1 Risk-Based Capital, Ratio	0.127	0.110
Total, Ratio	0.139	0.124
Tier 1 Leverage Capital, Minimum Capital Required, Amount	$ 2,502	$ 2,388.4
CET 1 Risk-Based Capital, Minimum Capital Required, Amount	2,925.6	3,155.3
Tier 1 Risk-Based Capital, Minimum Capital Required, Amount	3,552.5	3,831.4
Total, Minimum Capital Required, Amount	$ 4,388.3	$ 4,732.9
Tier 1 Leverage Capital, Ratio, Minimum Capital Required	0.040	0.040
CET 1 Risk-Based Capital, Ratio, Minimum Capital Required	7.00%	7.00%
Tier 1 Risk-Based Capital, Ratio, Minimum Capital Required	0.085	0.085
Total, Ratio, Minimum Capital Required	0.105	0.105
Tier 1 Risk-Based Capital, Well-Capitalized, Amount	$ 2,507.6	$ 2,704.5
Total, Well-Capitalized, Amount	$ 4,179.4	$ 4,507.5
Tier 1 Risk-Based Capital, Ratio, Well-Capitalized	0.060	0.060
Total, Ratio, Well-Capitalized	0.100	0.100
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Leverage Capital, Amount	$ 5,403.6	$ 5,168.4
CET 1 Risk-Based Capital, Amount	5,403.6	5,168.4
Tier 1 Risk-Based Capital	5,403.6	5,168.4
Total, Amount	$ 5,840.2	$ 5,745.1
Tier 1 Leverage Capital, Ratio	0.086	0.087
CET 1 Risk-Based Capital, Ratio	12.90%	11.50%
Tier 1 Risk-Based Capital, Ratio	0.129	0.115
Total, Ratio	0.140	0.128
Tier 1 Leverage Capital, Minimum Capital Required, Amount	$ 2,501.8	$ 2,387.9
CET 1 Risk-Based Capital, Minimum Capital Required, Amount	2,925	3,151.1
Tier 1 Risk-Based Capital, Minimum Capital Required, Amount	3,551.7	3,826.3
Total, Minimum Capital Required, Amount	$ 4,387.4	$ 4,726.7
Tier 1 Leverage Capital, Ratio, Minimum Capital Required	0.040	0.040
CET 1 Risk-Based Capital, Ratio, Minimum Capital Required	7.00%	7.00%
Tier 1 Risk-Based Capital, Ratio, Minimum Capital Required	0.085	0.085
Total, Ratio, Minimum Capital Required	0.105	0.105
Tier 1 Leverage Capital, Well-Capitalized, Amount	$ 3,127.2	$ 2,984.8
CET 1 Risk-Based Capital, Well-Capitalized, Amount	2,716	2,926
Tier 1 Risk-Based Capital, Well-Capitalized, Amount	3,342.8	3,601.3
Total, Well-Capitalized, Amount	$ 4,178.5	$ 4,501.6
Tier 1 Leverage Capital, Ratio , Well-Capitalized	0.050	0.050
CET 1 Risk-Based Capital, Ratio, Well-Capitalized	6.50%	6.50%
Tier 1 Risk-Based Capital, Ratio, Well-Capitalized	0.080	0.080
Total, Ratio, Well-Capitalized	0.100	0.100

Earnings Per Common Share - Bas

Earnings Per Common Share - Basic and Diluted Earnings Per Common Share, Reflecting Application of Two-Class Method (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 146.4	$ 136.2	$ 167.3	$ 141	$ (148.8)	$ 141.1	$ 86.4	$ 126.9	$ 590.8	$ 205.5	$ 506.3
Dividends paid on and undistributed earnings allocated to participating securities									0	0	(0.2)
Earnings attributable to common shareholders									$ 590.8	$ 205.5	$ 506.1
Weighted average common shares outstanding for basic EPS (in shares)	421,650	421,430	421,090	419,120	418,150	418,050	417,910	427,180	420,800	420,300	394,000
Effect of dilutive equity-based awards (in shares)									3,700	2,300	3,200
Weighted average common shares and common-equivalent shares for diluted EPS (in shares)	425,450	424,770	425,080	422,580	420,390	420,290	420,150	429,770	424,500	422,600	397,200
EPS:
Basic (in dollars per share)	$ 0.35	$ 0.32	$ 0.40	$ 0.34	$ (0.36)	$ 0.34	$ 0.21	$ 0.30	$ 1.40	$ 0.49	$ 1.28
Diluted (in dollars per share)	$ 0.34	$ 0.32	$ 0.39	$ 0.33	$ (0.35)	$ 0.34	$ 0.21	$ 0.30	$ 1.39	$ 0.49	$ 1.27

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Anti-dilutive equity-based awards excluded from calculation of diluted EPS (in shares)	11.3	18	6.7

Comprehensive Income - Schedule

Comprehensive Income - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 7,602.8	$ 7,947.2	$ 6,533.9
Other comprehensive income (loss) before reclassifications	(59.8)	69.3	79.1
Amounts reclassified from AOCL	12.2	8.4	10.8
Total other comprehensive (loss) income, net of tax	(47.6)	77.7	89.9
Ending Balance	7,901.8	7,602.8	7,947.2
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(89.2)	(166.9)	(256.8)
Total other comprehensive (loss) income, net of tax	(47.6)	77.7	89.9
Ending Balance	(136.8)	(89.2)	(166.9)
Pension and Other Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(181.8)	(176.2)	(192.5)
Other comprehensive income (loss) before reclassifications	61.7	(12)	9.7
Amounts reclassified from AOCL	7	6.4	6.6
Total other comprehensive (loss) income, net of tax	68.7	(5.6)	16.3
Ending Balance	(113.1)	(181.8)	(176.2)
Net Unrealized Gains (Losses) on Debt Securities Available-for-Sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	103.1	20.8	(47)
Other comprehensive income (loss) before reclassifications	(122.4)	82.3	67.9
Amounts reclassified from AOCL	0	0	(0.1)
Total other comprehensive (loss) income, net of tax	(122.4)	82.3	67.8
Ending Balance	(19.3)	103.1	20.8
Net Unrealized Gains (Losses) on Debt Securities Transferred to Held-to-Maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(8.2)	(11.8)	(15.3)
Other comprehensive income (loss) before reclassifications	0	0	0
Amounts reclassified from AOCL	3.8	3.6	3.5
Total other comprehensive (loss) income, net of tax	3.8	3.6	3.5
Ending Balance	(4.4)	(8.2)	(11.8)
Net Unrealized Gains (Losses) on Derivatives Accounted for as Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2.3)	0.3	(2)
Other comprehensive income (loss) before reclassifications	0.9	(1)	1.5
Amounts reclassified from AOCL	1.4	(1.6)	0.8
Total other comprehensive (loss) income, net of tax	2.3	(2.6)	2.3
Ending Balance	$ 0	$ (2.3)	$ 0.3

Comprehensive Income - Summary

Comprehensive Income - Summary of Amounts Reclassified from AOCL (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Non-interest income									$ 72.3	$ 112.1	$ 123.5
Interest and dividend income - securities									(28.8)	(31.8)	(34.9)
Income before income tax expense	$ 189.9	$ 169.4	$ 215.7	$ 182.2	$ (100.1)	$ 172.1	$ 110.4	$ 166.2	757.2	348.6	652.4
Income tax expense	(40)	(29.7)	(44.9)	(37.7)	(45.2)	(27.5)	(20.5)	(35.8)	(152.3)	(129)	(132)
Net income	$ 149.9	$ 139.7	$ 170.8	$ 144.5	$ (145.3)	$ 144.6	$ 89.9	$ 130.4	604.9	219.6	520.4
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income									(12.2)	(8.4)	(10.8)
Pension and Other Postretirement Plans | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income tax expense									(9)	(8.4)	(8.3)
Income tax expense									2	2	1.7
Net income									(7)	(6.4)	(6.6)
Net actuarial loss | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Non-interest income									(9)	(8.4)	(8.3)
Net Unrealized Gains (Losses) on Debt Securities Available-for-Sale | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income tax expense									0	0	0.1
Income tax expense									0	0	0
Net income									0	0	0.1
Net Unrealized Gains (Losses) on Debt Securities Transferred to Held-to-Maturity | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income tax expense									(4.9)	(4.7)	(4.6)
Income tax expense									1.1	1.1	1.1
Net income									(3.8)	(3.6)	(3.5)
Net Unrealized Gains (Losses) on Derivatives Accounted for as Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income tax expense									(1.8)	2	(1.1)
Income tax expense									0.4	(0.4)	0.3
Net income									(1.4)	1.6	(0.8)
Net Unrealized Gains (Losses) on Derivatives Accounted for as Cash Flow Hedges | Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and dividend income - securities									(1.9)	1.9	(1.2)
Net Unrealized Gains (Losses) on Derivatives Accounted for as Cash Flow Hedges | Interest rate locks | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and dividend income - securities									$ 0.1	$ 0.1	$ 0.1

Comprehensive Income - Deferred

Comprehensive Income - Deferred Income Taxes Applicable to Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred income taxes	$ 44.6	$ 28.1	$ 52.2
Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred income taxes	36.9	57	55.3
Net Unrealized Gains (Losses) on Debt Securities Available-for-Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred income taxes	6.3	(32.1)	(6.6)
Net Unrealized Gains (Losses) on Debt Securities Transferred to Held-to-Maturity
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred income taxes	1.4	2.5	3.6
Net Unrealized Gains (Losses) on Derivatives Accounted for as Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred income taxes	$ 0	$ 0.7	$ (0.1)

Comprehensive Income - Other Co

Comprehensive Income - Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before reclassifications, after tax amount	$ (59.8)	$ 69.3	$ 79.1
Reclassification adjustment, after-tax amount	12.2	8.4	10.8
Other comprehensive income (loss), pre-tax amount	(64.1)	101.8	117.1
Other comprehensive income (loss), tax effect	16.5	(24.1)	(27.2)
Total other comprehensive (loss) income, net of tax	(47.6)	77.7	89.9
Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before reclassifications, pre-tax amount	79.8	(15.7)	12.1
OCI, before reclassification, tax effect	(18.1)	3.7	(2.4)
OCI, before reclassifications, after tax amount	61.7	(12)	9.7
Reclassification adjustment, pre-tax amount	9	8.4	8.3
Reclassification adjustment, tax effect	(2)	(2)	(1.7)
Reclassification adjustment, after-tax amount	7	6.4	6.6
Other comprehensive income (loss), pre-tax amount	88.8	(7.3)	20.4
Other comprehensive income (loss), tax effect	(20.1)	1.7	(4.1)
Total other comprehensive (loss) income, net of tax	68.7	(5.6)	16.3
Net Unrealized Gains (Losses) on Debt Securities Available-for-Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before reclassifications, pre-tax amount	(160.8)	107.8	89.2
OCI, before reclassification, tax effect	38.4	(25.5)	(21.3)
OCI, before reclassifications, after tax amount	(122.4)	82.3	67.9
Reclassification adjustment, pre-tax amount			(0.1)
Reclassification adjustment, tax effect			0
Reclassification adjustment, after-tax amount	0	0	(0.1)
Other comprehensive income (loss), pre-tax amount	(160.8)	107.8	89.1
Other comprehensive income (loss), tax effect	38.4	(25.5)	(21.3)
Total other comprehensive (loss) income, net of tax	(122.4)	82.3	67.8
Net Unrealized Gains (Losses) on Debt Securities Transferred to Held-to-Maturity
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before reclassifications, after tax amount	0	0	0
Reclassification adjustment, pre-tax amount	4.9	4.7	4.6
Reclassification adjustment, tax effect	(1.1)	(1.1)	(1.1)
Reclassification adjustment, after-tax amount	3.8	3.6	3.5
Other comprehensive income (loss), pre-tax amount	4.9	4.7	4.6
Other comprehensive income (loss), tax effect	(1.1)	(1.1)	(1.1)
Total other comprehensive (loss) income, net of tax	3.8	3.6	3.5
Net Unrealized Gains (Losses) on Derivatives Accounted for as Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, before reclassifications, pre-tax amount	1.2	(1.4)	1.9
OCI, before reclassification, tax effect	(0.3)	0.4	(0.4)
OCI, before reclassifications, after tax amount	0.9	(1)	1.5
Reclassification adjustment, pre-tax amount	1.8	(2)	1.1
Reclassification adjustment, tax effect	(0.4)	0.4	(0.3)
Reclassification adjustment, after-tax amount	1.4	(1.6)	0.8
Other comprehensive income (loss), pre-tax amount	3	(3.4)	3
Other comprehensive income (loss), tax effect	(0.7)	0.8	(0.7)
Total other comprehensive (loss) income, net of tax	$ 2.3	$ (2.6)	$ 2.3

Employee Benefit Plans - People

Employee Benefit Plans - People's United Employee Pension and Other Postretirement Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Average compensation term on which pension plan benefits are based, in years			5 years
Average compensation term within last ten years on which pension plan benefits are based, in years			5 years
Term considered when determining employee pension benefits, in years			10 years
Trust assets		$ 94.5	$ 94.5	$ 56.9
Maximum percentage of fixed income holdings invested in issues rated below Baa			30.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of covered employee's eligible compensation			4.00%
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations:		699.6	$ 699.6	740.5	$ 665.5
Defined benefit plan, expected future benefit payments in year one		31.3	31.3
Defined benefit plan, expected future benefit payments in year two		32.9	32.9
Defined benefit plan, expected future benefit payments in year three		34.8	34.8
Defined benefit plan, expected future benefit payments in year four		35	35
Defined benefit plan, expected future benefit payments in year five		37.4	37.4
Defined benefit plan, expected future benefit payments after five years		193.9	193.9
Pension Plans | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Trust assets		40.5	40.5
Projected benefit obligations:		35.3	35.3	41.8
Pension Plans | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations:		$ 664.3	664.3	$ 698.7
Net periodic benefit income			$ 35.6
Maximum percentage of any individual security			3.00%
Percentage of equity holdings invested in international equities			50.00%
Maximum percentage of fixed income holdings invested in issues rated below Baa			2.50%
Market value of total plan assets			2.50%
Pension Plans | Qualified Plan | People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of covered employee's eligible compensation			3.00%
Minimum age requirement to participate in pension plan, years			18 years
Minimum service hours per year requirement to participate in pension plan			1000 hours
Amortization of unrecognized gain loss over average remaining life of plan participants			24 years
Discount rate used to determine benefit obligation		2.86%	2.86%	2.50%	3.38%
Discount rate used to calculate net periodic benefit cost	2.50%	3.14%		3.38%	4.41%
Expected long-term rate of return assumption			7.25%	7.25%	7.25%
Expected long-term rate of return assumption			7.25%
Discount rate			2.86%
Pension Plans | Qualified Plan | United Financial Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to determine benefit obligation				2.53%	3.42%
Discount rate used to calculate net periodic benefit cost			2.53%	3.42%	3.33%
Expected long-term rate of return assumption			5.25%	5.25%	5.25%
Pension Plans | Minimum | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to determine benefit obligation		2.18%	2.18%	1.60%
Discount rate used to calculate net periodic benefit cost			1.84%	1.29%
Pension Plans | Minimum | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated unrecognized gain or loss percentage for amortization of actuarial gain loss			10.00%
Pension Plans | Minimum | Qualified Plan | People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to calculate net periodic benefit cost	2.50%
Pension Plans | Maximum | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to determine benefit obligation		2.90%	2.90%	2.50%
Discount rate used to calculate net periodic benefit cost			2.90%	2.50%
Pension Plans | Maximum | Qualified Plan | People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to calculate net periodic benefit cost		3.14%
Other Pension Plan, Postretirement or Supplemental Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions		$ 4.1	$ 4.1
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations:		16.5	16.5	$ 17.7	$ 18.7
Defined benefit plan, expected future benefit payments in year one		1.1	1.1
Defined benefit plan, expected future benefit payments in year two		1.1	1.1
Defined benefit plan, expected future benefit payments in year three		1.1	1.1
Defined benefit plan, expected future benefit payments in year four		1.1	1.1
Defined benefit plan, expected future benefit payments in year five		1	1
Defined benefit plan, expected future benefit payments after five years		$ 4.6	$ 4.6
Other Postretirement Plans | People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to determine benefit obligation		2.90%	2.90%	2.50%	3.40%
Discount rate used to calculate net periodic benefit cost			2.50%	3.40%	4.40%

Employee Benefit Plans - Change

Employee Benefit Plans - Changes in Benefit Obligations and Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Pension Plans
Benefit Obligation
Beginning of year	$ 740.5	$ 665.5
Service cost	0	0
Interest cost	16.2	19.7
Actuarial loss (gain)	(24.8)	85.9
Benefits paid	(29.6)	(30)
Settlements	(2.7)	(0.6)
End of year	699.6	740.5
Fair value of plan assets:
Beginning of year	839.9	746.7
Actual return on assets	107.7	120.2
Employer contributions	5.4	3.6
Benefits paid	(29.6)	(30)
Settlements	(2.7)	(0.6)
End of year	920.7	839.9
Funded status at end of year	221.1	99.4
Amounts recognized in the Consolidated Statements of Condition:
Other assets	256.4	141.2
Other liabilities	(35.3)	(41.8)
Funded status at end of year	221.1	99.4
Other Postretirement Plans
Benefit Obligation
Beginning of year	17.7	18.7
Service cost	0.3	0.3
Interest cost	0.4	0.6
Actuarial loss (gain)	(1.3)	(1.5)
Benefits paid	(0.6)	(0.4)
Settlements	0	0
End of year	16.5	17.7
Fair value of plan assets:
Beginning of year	0	0
Actual return on assets	0	0
Employer contributions	0.6	0.4
Benefits paid	(0.6)	(0.4)
Settlements	0	0
End of year	0	0
Funded status at end of year	(16.5)	(17.7)
Amounts recognized in the Consolidated Statements of Condition:
Other assets	0	0
Other liabilities	(16.5)	(17.7)
Funded status at end of year	$ (16.5)	$ (17.7)

Employee Benefit Plans - Accumu

Employee Benefit Plans - Accumulated and Projected Benefit Obligations (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations:	$ 86.8	$ 89.5
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations:	699.3	740.3
Projected benefit obligations:	699.6	740.5	$ 665.5
Pension Plans | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations:	664.3	698.7
Projected benefit obligations:	664.3	698.7
Pension Plans | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations:	35	41.6
Projected benefit obligations:	$ 35.3	$ 41.8

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit (Income) Expense and Other Amounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss	$ (79.8)	$ 15.7	$ (12.1)
Pension Plans
Net periodic benefit (income) expense:
Interest cost	16.2	19.7	22.9
Expected return on plan assets	(54.2)	(49.5)	(46.1)
Recognized net actuarial loss	8.2	7.9	5.3
Settlements	0.8	0.2	2.9
Net periodic benefit (income) expense	(29)	(21.7)	(15)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss	(87.3)	7.5	(20.5)
Total pre-tax changes recognized in other comprehensive income (loss)	(87.3)	7.5	(20.5)
Total recognized in net periodic benefit (income) expense and other comprehensive income (loss)	(116.3)	(14.2)	(35.5)
Other Postretirement Plans
Net periodic benefit (income) expense:
Interest cost	0.7	0.9	0.9
Expected return on plan assets	0	0	0
Recognized net actuarial loss	0	0.2	0.1
Settlements	0	0	0
Net periodic benefit (income) expense	0.7	1.1	1
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss	(1.3)	(1.6)	1.1
Total pre-tax changes recognized in other comprehensive income (loss)	(1.3)	(1.6)	1.1
Total recognized in net periodic benefit (income) expense and other comprehensive income (loss)	$ (0.6)	$ (0.5)	$ 2.1

Employee Benefit Plans - Pre-Ta

Employee Benefit Plans - Pre-Tax Amounts in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 148.7	$ 236
Total pre-tax amounts included in AOCL	148.7	236
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	1	2.3
Total pre-tax amounts included in AOCL	$ 1	$ 2.3

Employee Benefit Plans - Assump

Employee Benefit Plans - Assumptions Used in Determining Benefit Obligations and Net Periodic Benefit Expense (Detail)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assumed health care cost trend rates at December 31:
Health care cost trend rate assumed for next year		5.20%	5.20%	5.50%	5.70%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		4.50%	4.50%	4.50%	4.50%
Year that the rate reaches the ultimate trend rate			2037	2037	2037
Pension Plans | People's Qualified Plan | Qualified Plan
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate:		2.86%	2.86%	2.50%	3.38%
Weighted-average assumptions used to determine net periodic benefit (income) expense for the years ended December 31:
Discount rate:	2.50%	3.14%		3.38%	4.41%
Expected return on plan assets:			7.25%	7.25%	7.25%
Pension Plans | People's Qualified Plan | Qualified Plan | Minimum
Weighted-average assumptions used to determine net periodic benefit (income) expense for the years ended December 31:
Discount rate:	2.50%
Pension Plans | People's Qualified Plan | Qualified Plan | Maximum
Weighted-average assumptions used to determine net periodic benefit (income) expense for the years ended December 31:
Discount rate:		3.14%
Pension Plans | First Connecticut Qualified Plan | Qualified Plan
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate:					3.39%
Weighted-average assumptions used to determine net periodic benefit (income) expense for the years ended December 31:
Discount rate:				3.39%	4.41%
Expected return on plan assets:					6.00%
Pension Plans | United Financial Qualified Plan | Qualified Plan
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate:				2.53%	3.42%
Weighted-average assumptions used to determine net periodic benefit (income) expense for the years ended December 31:
Discount rate:			2.53%	3.42%	3.33%
Expected return on plan assets:			5.25%	5.25%	5.25%
Other Postretirement Plans | People's Qualified Plan
Weighted-average assumptions used to determine benefit obligations at December 31:
Discount rate:		2.90%	2.90%	2.50%	3.40%
Weighted-average assumptions used to determine net periodic benefit (income) expense for the years ended December 31:
Discount rate:			2.50%	3.40%	4.40%

Employee Benefit Plans - Assets

Employee Benefit Plans - Assets Allocation (Detail) - Pension Plans - Qualified Plan	Dec. 31, 2021
Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	1.00%
Cash equivalents | Minimum
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	0.00%
Cash equivalents | Maximum
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	20.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	71.00%
Equity securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	55.00%
Equity securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	75.00%
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	28.00%
Fixed income securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	10.00%
Fixed income securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Policy target percentage	40.00%

Employee Benefit Plans - Fair V

Employee Benefit Plans - Fair Value of Assets in Qualified Plans (Detail) - Pension Plans - Qualified Plan	Dec. 31, 2021	Dec. 31, 2020
People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets	100.00%	100.00%
United Financial Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets		100.00%
Equity securities | People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets	70.00%	70.00%
Equity securities | United Financial Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets		4.00%
Cash and fixed income securities | People's Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets	30.00%	30.00%
Cash and fixed income securities | United Financial Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets		96.00%

Employee Benefit Plans - Plan A

Employee Benefit Plans - Plan Assets Measured at Fair Value (Detail) - Pension Plans - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	$ 920.7	$ 839.9	$ 746.7
Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	920.7	839.9
Cash equivalents | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	41.5	23.9
Common stocks | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	353.5	302.6
Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	287.1	259.6
U.S. Treasury and agency | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	43.9	52.5
Corporate | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	75.8	96.5
Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	118.1	103.3
Other | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0.8	1.5
Level 1   | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	395	326.5
Level 1   | Cash equivalents | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	41.5	23.9
Level 1   | Common stocks | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	353.5	302.6
Level 1   | Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 1   | U.S. Treasury and agency | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 1   | Corporate | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 1   | Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 1   | Other | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 2   | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	525.7	513.4
Level 2   | Cash equivalents | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 2   | Common stocks | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 2   | Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	287.1	259.6
Level 2   | U.S. Treasury and agency | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	43.9	52.5
Level 2   | Corporate | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	75.8	96.5
Level 2   | Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	118.1	103.3
Level 2   | Other | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0.8	1.5
Level 3   | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | Cash equivalents | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | Common stocks | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | U.S. Treasury and agency | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | Corporate | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | Mutual funds | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	0	0
Level 3   | Other | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets measured at fair value	$ 0	$ 0

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Stock Ownership Plan - Additional Information (Detail) - USD ($) $ in Millions	Apr. 30, 2007	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
ESOP loan	$ 216.8	$ 161.2
ESOP, shares to be purchased (in shares)	10,453,575
Loan repayments expected annual through 2036		18.8
Cash dividends paid on unallocated ESOP shares		$ 4.1	$ 4.3	$ 4.4
Minimum age requirement to participate in ESOP		18 years
Minimum work experience within 12 months of hire needed to participate in ESOP		1000 hours
ESOP common stock allocated (in shares)		5,226,788
Unallocated common stock of Employee Stock Ownership Plan (in shares)		5,226,787	5,600,000
Fair value of deferred ESOP shares		$ 93.1
ESOP compensation expense		$ 5.9	$ 4.3	$ 5.7

Employee Benefit Plans - Empl_2

Employee Benefit Plans - Employee Savings Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage of pre-tax compensation an employee can contribute to savings plan	50.00%
Percentage of matching contribution on employee savings plan	100.00%
Trust assets	$ 94.5	$ 56.9
Employee savings plan expense	679.6	674.8	$ 646.2
Employee Savings Plan | Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Trust assets	54
Related benefit obligation	51.5
Employee savings plan expense	$ 34.2	$ 35.5	$ 32.3
Maximum
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage employer will match on pre-tax compensation	4.00%

Stock Based Compensation Plans

Stock Based Compensation Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting period						1 year
Expense related to share-based awards	$ 27,600	$ 26,200	$ 24,900
Long-term incentive plan (in shares)	2,322,549	3,419,934	2,807,692
Total cost of shares repurchased and retired	$ 2,100	$ 1,700	$ 2,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense related to share-based awards	14,200	11,200	12,200
Unamortized cost for unvested options and awards	$ 12,300
Weighted-average vesting period, years	1 year 9 months 18 days
Fair value of restricted stock awards	$ 9,400	7,200	7,700
Unamortized cost for share-based awards estimated forfeiture rate	5.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense related to share-based awards	$ 5,500	6,300	5,200
Unamortized cost for unvested options and awards	$ 4,600
Weighted-average vesting period, years	1 year 8 months 12 days
Unamortized cost for share-based awards estimated forfeiture rate	5.00%
Intrinsic value of stock options exercised	$ 9,700	100	3,200
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense related to share-based awards	7,100	7,800	6,600
Unamortized cost for unvested options and awards	$ 6,300
Weighted-average vesting period, years	1 year 8 months 12 days
Fair value of restricted stock awards	$ 6,800	$ 5,900	$ 6,000
Unamortized cost for share-based awards estimated forfeiture rate	5.00%
Minimum tax withholding obligations upon the vesting of restricted stock awards granted (in shares)	119,143	117,125	115,632
Total cost of shares repurchased and retired	$ 2,200	$ 1,600	$ 2,000
Share based compensation arrangement by share based payment award grants in period weighted average grant date fair value (in dollars per share)	$ 15.29	$ 14.60	$ 17.44
2007 Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and stock options per year over a five year period, in years					20.00%
2007 Plans | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award service period					5 years
2014 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock reserved for issuance under the Directors' Equity Plan (in shares)	75,850,000
Reserved shares remaining, available for future awards (in shares)	15,562,209
2014 Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares depleted for every share subject to award other than option or stock appreciation right (in shares)	7.98
Performance period	3 years
Share based compensation arrangement by share based payment award grants in period weighted average grant date fair value (in dollars per share)	$ 15.57	$ 16.75	$ 17.84
2014 Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares depleted for every share subject to award other than option or stock appreciation right (in shares)	5.32
Options granted, vesting period	3 years			3 years
2014 Plan | Restricted Stock | Tranche 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	33.00%
2014 Plan | Restricted Stock | Tranche 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	33.00%
2014 Plan | Restricted Stock | Tranche 3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	33.00%
Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under the Incentive Plans after two years						66.00%	50.00%
Options granted under the Incentive Plans after three years						100.00%	75.00%
Options granted under the Incentive Plans after four years							100.00%
Options granted under the Incentive Plans after one year						33.00%
New awards granted (in shares)	0
Long-term incentive plan (in shares)	2,322,549	3,419,934	2,807,692
Weighted-average grant-date fair value of options (in dollars per share)	$ 2.73	$ 1.67	$ 2.04
Expected volatility rate	33.00%	21.00%	19.00%
Dividend yield	4.70%	4.40%	4.00%
Risk-free interest rate	0.70%	1.40%	2.60%
Expected option life, years	5 years	4 years	4 years
Incentive Plans | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration, maximum term							10 years
Directors' Equity Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock reserved for issuance under the Directors' Equity Plan (in shares)	1,492,500
Reserved shares remaining, available for future awards (in shares)	214,452
Expense related to share-based awards	$ 800	$ 900	$ 900
New awards granted (in shares)	44,262	75,267	58,340
Director's equity compensation plan fair value	$ 95
Share based compensation arrangement by share based payment award grants in period weighted average grant date fair value (in dollars per share)	$ 19.36	$ 11.30	$ 16.31

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans - Summary of Performance Share Activity (Detail) - 2014 Plan - Performance Shares - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares
Unvested shares outstanding, beginning balance (in shares)	1,719,081	1,504,416	1,453,372
Granted (in shares)	832,965	691,989	637,118
Change in shares based on approved performance factors (in shares)	94,341	79,623
Forfeited (in shares)	(43,032)	(55,378)	(80,319)
Vested (in shares)	(569,476)	(501,569)	(505,755)
Unvested shares outstanding, ending balance (in shares)	2,033,879	1,719,081	1,504,416
Weighted-average grant date fair value
Unvested shares outstanding, beginning balance (in dollars per share)	$ 17.94	$ 18.68	$ 17.85
Granted (in dollars per share)	15.57	16.75	17.84
Change in shares based on approved performance factors (in dollars per share)	19.71	18.60
Forfeited (in dollars per share)	16.44	17.90	18.66
Vested (in dollars per share)	19.77	18.60	15.23
Unvested shares outstanding, ending balance (in dollars per share)	$ 16.58	$ 17.94	$ 18.68

Stock Based Compensation Plan_2

Stock Based Compensation Plans - Summary of Stock Option Incentive Plan (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares Subject To Option
Options outstanding beginning balance (in shares)	18,022,272	15,198,823	14,677,067
Granted (in shares)	2,322,549	3,419,934	2,807,692
Forfeited (in shares)	(221,074)	(552,726)	(652,965)
Exercised (in shares)	(2,790,967)	(43,759)	(1,632,971)
Options outstanding, ending balance (in shares)	17,332,780	18,022,272	15,198,823
Options exercisable ending balance (in shares)	12,134,430
Weighted-Average Exercise Price
Options outstanding, beginning balance (in dollars per share)	$ 16.19	$ 16.20	$ 15.87
Granted (in dollars per share)	15.29	16.21	17.62
Forfeited (in dollars per share)	17.24	16.65	18.28
Exercised (in dollars per share)	14.50	14.91	14.77
Options outstanding, ending balance (in dollars per share)	16.33	$ 16.19	$ 16.20
Options exercisable weighted average exercise price (in dollars per share)	$ 16.46
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding weighted average remaining contractual term, in years	5 years 8 months 12 days
Options exercisable weighted average remaining contractual term	4 years 7 months 6 days
Options outstanding aggregate intrinsic value	$ 32.4
Options exercisable aggregate intrinsic value	$ 22.6

Stock Based Compensation Plan_3

Stock Based Compensation Plans - Summary of Option Outstanding and Exercisable (Detail)	12 Months Ended
	Dec. 31, 2021$ / sharesshares
$11.29 — $14.71
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Exercise Price minimum (in dollars per share)	$ 11.29
Options Exercise Price maximum (in dollars per share)	$ 14.71
Number of options outstanding (in dollars per share) | shares	3,708,487
Remaining Life	2 years 9 months 18 days
Exercise Price (in dollars per share)	$ 14.04
Number of options exercisable | shares	3,704,519
Weighted Average Exercise Price (in dollars per share)	$ 14.04
14.72 — 15.75
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Exercise Price minimum (in dollars per share)	14.72
Options Exercise Price maximum (in dollars per share)	$ 15.75
Number of options outstanding (in dollars per share) | shares	4,565,982
Remaining Life	6 years 1 month 6 days
Exercise Price (in dollars per share)	$ 15.07
Number of options exercisable | shares	2,305,988
Weighted Average Exercise Price (in dollars per share)	$ 14.85
15.76 — 18.40
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Exercise Price minimum (in dollars per share)	15.76
Options Exercise Price maximum (in dollars per share)	$ 18.40
Number of options outstanding (in dollars per share) | shares	5,303,025
Remaining Life	7 years 8 months 12 days
Exercise Price (in dollars per share)	$ 16.81
Number of options exercisable | shares	2,368,637
Weighted Average Exercise Price (in dollars per share)	$ 17.08
18.41 — 19.71
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Exercise Price minimum (in dollars per share)	18.41
Options Exercise Price maximum (in dollars per share)	$ 19.71
Number of options outstanding (in dollars per share) | shares	3,755,286
Remaining Life	5 years 7 months 6 days
Exercise Price (in dollars per share)	$ 19.45
Number of options exercisable | shares	3,755,286
Weighted Average Exercise Price (in dollars per share)	$ 19.45

Stock Based Compensation Plan_4

Stock Based Compensation Plans - Summary of Restricted Stock Activity (Detail) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares
Unvested shares outstanding, beginning balance (in shares)	906,572	698,801	730,550
Granted (in shares)	474,766	562,739	383,420
Forfeited (in shares)	(54,921)	(28,090)	(68,091)
Vested (in shares)	(411,720)	(326,878)	(347,078)
Unvested shares outstanding, ending balance (in shares)	914,697	906,572	698,801
Weighted-average grant date fair value
Unvested shares outstanding, beginning balance (in dollars per share)	$ 15.85	$ 18.07	$ 18.03
Granted (in dollars per share)	15.29	14.60	17.44
Forfeited (in dollars per share)	15.07	17.31	17.11
Vested (in dollars per share)	16.59	18.33	17.49
Unvested shares outstanding, ending balance (in dollars per share)	$ 15.27	$ 15.85	$ 18.07

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021trust
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of trusts funded to provide benefit payments	2
GSE mortgage-backed securities | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of available-for-sale residential mortgage-backed securities portfolio	7 years
GSE mortgage-backed securities | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of available-for-sale residential mortgage-backed securities portfolio	40 years
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount to impaired loans	10.00%

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financial assets:
Debt securities available-for-sale, at fair value	$ 6,644	$ 4,925.5
Equity securities	0	5.3
Fair value of derivative financial instruments	27	18.6
Financial liabilities:
Fair value of derivative financial instruments	79	168.6
Fair Value, Recurring
Financial assets:
Equity securities		5.3
Total	7,126.6	5,788
Financial liabilities:
Total	95.3	170.4
Exchange-traded funds | Fair Value, Recurring
Financial assets:
Other assets	89.2	53
Mutual funds | Fair Value, Recurring
Financial assets:
Other assets	5.3	3.9
U.S. Treasury and agency
Financial assets:
Debt securities available-for-sale, at fair value	636.7	541.6
U.S. Treasury and agency | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	636.7	541.6
GSE mortgage-backed securities
Financial assets:
Debt securities available-for-sale, at fair value	6,007.3	4,383.9
GSE mortgage-backed securities | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	6,007.3	4,383.9
Interest rate swaps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	384	783.8
Financial liabilities:
Fair value of derivative financial instruments	90.8	157.2
Interest rate caps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	1.7	3
Financial liabilities:
Fair value of derivative financial instruments	1.7	3
Foreign exchange contracts | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	2.4	12.8
Financial liabilities:
Fair value of derivative financial instruments	2.6	8.8
Forward commitments to sell residential mortgage loans | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0.7
Forward commitments to sell residential mortgage loans | Fair Value, Recurring | Maximum
Financial assets:
Fair value of derivative financial instruments	0.1
Risk participation agreements | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0.2	0.4
Interest rate-lock commitments on residential mortgage loans | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0	1
Interest rate-lock commitments on residential mortgage loans | Fair Value, Recurring | Maximum
Financial liabilities:
Fair value of derivative financial instruments	0.1
Level 1   | Fair Value, Recurring
Financial assets:
Equity securities		5.3
Total	731.2	603.8
Financial liabilities:
Total	0	0
Level 1   | Exchange-traded funds | Fair Value, Recurring
Financial assets:
Other assets	89.2	53
Level 1   | Mutual funds | Fair Value, Recurring
Financial assets:
Other assets	5.3	3.9
Level 1   | U.S. Treasury and agency | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	636.7	541.6
Level 1   | GSE mortgage-backed securities | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	0	0
Level 1   | Interest rate swaps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 1   | Interest rate caps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 1   | Foreign exchange contracts | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 1   | Forward commitments to sell residential mortgage loans | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Level 1   | Risk participation agreements | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 1   | Interest rate-lock commitments on residential mortgage loans | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 2   | Fair Value, Recurring
Financial assets:
Equity securities		0
Total	6,395.4	5,184.2
Financial liabilities:
Total	95.3	170.4
Level 2   | Exchange-traded funds | Fair Value, Recurring
Financial assets:
Other assets	0	0
Level 2   | Mutual funds | Fair Value, Recurring
Financial assets:
Other assets	0	0
Level 2   | U.S. Treasury and agency | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	0	0
Level 2   | GSE mortgage-backed securities | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	6,007.3	4,383.9
Level 2   | Interest rate swaps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	384	783.8
Financial liabilities:
Fair value of derivative financial instruments	90.8	157.2
Level 2   | Interest rate caps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	1.7	3
Financial liabilities:
Fair value of derivative financial instruments	1.7	3
Level 2   | Foreign exchange contracts | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	2.4	12.8
Financial liabilities:
Fair value of derivative financial instruments	2.6	8.8
Level 2   | Forward commitments to sell residential mortgage loans | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0.7
Level 2   | Risk participation agreements | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0.2	0.4
Level 2   | Interest rate-lock commitments on residential mortgage loans | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0	1
Level 3   | Fair Value, Recurring
Financial assets:
Equity securities		0
Total	0	0
Financial liabilities:
Total	0	0
Level 3   | Exchange-traded funds | Fair Value, Recurring
Financial assets:
Other assets	0	0
Level 3   | Mutual funds | Fair Value, Recurring
Financial assets:
Other assets	0	0
Level 3   | U.S. Treasury and agency | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	0	0
Level 3   | GSE mortgage-backed securities | Fair Value, Recurring
Financial assets:
Debt securities available-for-sale, at fair value	0	0
Level 3   | Interest rate swaps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 3   | Interest rate caps | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 3   | Foreign exchange contracts | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 3   | Forward commitments to sell residential mortgage loans | Fair Value, Recurring
Financial assets:
Fair value of derivative financial instruments	0	0
Level 3   | Risk participation agreements | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	0	0
Level 3   | Interest rate-lock commitments on residential mortgage loans | Fair Value, Recurring
Financial liabilities:
Fair value of derivative financial instruments	$ 0	$ 0

Fair Value Measurements - Ass_2

Fair Value Measurements - Assets Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 2,680,800,000	$ 2,680,800,000	$ 3,065,500,000
Loans held-for-sale	8,800,000	26,500,000
Mortgage servicing rights	4,300,000	4,800,000
Allowance for loan losses	343,600,000	425,100,000	246,600,000	$ 240,400,000
Provision for credit losses on loans (note 6)	(48,200,000)	156,100,000	$ 28,300,000
Repossessed assets	3,700,000	5,700,000
Nonoperating Income (Expense)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Write downs and net loss on sale of foreclosed/repossessed assets charged to non-interest expense total	(100,000)	5,200,000
REO and Repossessed Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Provision for credit losses on loans (note 6)	1,100,000	4,600,000
Residential mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value adjustments	0	0
Real estate owned	1,400,000	3,200,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		2,680,800,000
Loans held-for-sale	8,800,000
REO and repossessed assets	5,100,000	12,500,000
Mortgage servicing rights	4,300,000	4,800,000
Total	43,500,000	2,757,400,000
Fair value adjustments	(500,000)	(5,800,000)
Fair Value, Measurements, Nonrecurring | Collateral Pledged
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	25,300,000	32,800,000
Fair Value, Measurements, Nonrecurring | Residential mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		26,500,000
Fair Value, Measurements, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		0
Loans held-for-sale	0
REO and repossessed assets	0	0
Mortgage servicing rights	0	0
Total	0	0
Fair Value, Measurements, Nonrecurring | Level 1   | Collateral Pledged
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	0	0
Fair Value, Measurements, Nonrecurring | Level 1   | Residential mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		0
Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		0
Loans held-for-sale	8,800,000
REO and repossessed assets	0	0
Mortgage servicing rights	0	0
Total	8,800,000	26,500,000
Fair Value, Measurements, Nonrecurring | Level 2   | Collateral Pledged
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	0	0
Fair Value, Measurements, Nonrecurring | Level 2   | Residential mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		26,500,000
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		2,680,800,000
Loans held-for-sale	0
REO and repossessed assets	5,100,000	12,500,000
Mortgage servicing rights	4,300,000	4,800,000
Total	34,700,000	2,730,900,000
Fair Value, Measurements, Nonrecurring | Level 3   | Collateral Pledged
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	25,300,000	32,800,000
Allowance for loan losses	13,600,000	20,500,000
Provision for credit losses on loans (note 6)	$ 3,600,000	22,000,000
Fair Value, Measurements, Nonrecurring | Level 3   | Residential mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale		$ 0

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amounts and Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 320.5	$ 477.3
Short-term investments	10,268.8	3,766
Debt securities held-to-maturity, net	3,843	3,995.4
FRB and FHLB stock	264.6	266.6
Time deposits	3,696.7	5,658.8
FHLB advances	562.6	569.7	$ 3,125.4
Customer repurchase agreements	395.2	452.9	409.1
Federal funds purchased	0	125	$ 1,620
Notes and debentures	992.8	1,009.6
Collateral Pledged | Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Collateral dependent loans	25.3	32.8
Level 1   | Collateral Pledged | Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Collateral dependent loans	0	0
Level 2   | Collateral Pledged | Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Collateral dependent loans	0	0
Level 3   | Collateral Pledged | Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Collateral dependent loans	25.3	32.8
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	320.5	477.3
Short-term investments	10,268.8	3,766
Debt securities held-to-maturity, net	3,841.5	3,993.8
FRB and FHLB stock	264.6	266.6
Total loans, net	37,482.4	43,411.6
Time deposits	3,696.7	5,658.8
Other deposits	50,058.6	46,478.9
FHLB advances	562.6	569.7
Customer repurchase agreements	395.2	452.9
Federal funds purchased		125
Notes and debentures	992.8	1,009.6
Estimated Fair Value Measurements
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	320.5	477.3
Short-term investments	10,268.8	3,766
Debt securities held-to-maturity, net	4,036.1	4,267
FRB and FHLB stock	264.6	266.6
Total loans, net	37,543.1	43,833.4
Time deposits	3,703.3	5,699.7
Other deposits	50,058.6	46,478.9
FHLB advances	562.7	570.3
Customer repurchase agreements	395.2	452.9
Federal funds purchased		125
Notes and debentures	1,010.6	1,035.8
Estimated Fair Value Measurements | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	320.5	477.3
Short-term investments	0	0
Debt securities held-to-maturity, net	0	0
FRB and FHLB stock	0	0
Total loans, net	0	0
Time deposits	0	0
Other deposits	0	0
FHLB advances	0	0
Customer repurchase agreements	0	0
Federal funds purchased		0
Notes and debentures	0	0
Estimated Fair Value Measurements | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Short-term investments	10,268.8	3,766
Debt securities held-to-maturity, net	4,034.6	4,265.5
FRB and FHLB stock	264.6	266.6
Total loans, net	6,906.6	8,539.4
Time deposits	3,703.3	5,699.7
Other deposits	50,058.6	46,478.9
FHLB advances	562.7	570.3
Customer repurchase agreements	395.2	452.9
Federal funds purchased		125
Notes and debentures	1,010.6	1,035.8
Estimated Fair Value Measurements | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Short-term investments	0	0
Debt securities held-to-maturity, net	1.5	1.5
FRB and FHLB stock	0	0
Total loans, net	30,636.5	35,294
Time deposits	0	0
Other deposits	0	0
FHLB advances	0	0
Customer repurchase agreements	0	0
Federal funds purchased		0
Notes and debentures	$ 0	$ 0

Financial Instruments - Summary

Financial Instruments - Summary of Contractual or Notional Amounts of Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Commercial and industrial
Derivative Instruments And Hedging Activities [Line Items]
Loan origination commitments and unadvanced lines of credit:	$ 8,332.8	$ 6,723.5
Home equity and other consumer
Derivative Instruments And Hedging Activities [Line Items]
Loan origination commitments and unadvanced lines of credit:	3,536.5	3,349.5
Commercial real estate
Derivative Instruments And Hedging Activities [Line Items]
Loan origination commitments and unadvanced lines of credit:	795.1	962.4
Equipment financing
Derivative Instruments And Hedging Activities [Line Items]
Loan origination commitments and unadvanced lines of credit:	655.6	437.6
Residential Mortgage
Derivative Instruments And Hedging Activities [Line Items]
Loan origination commitments and unadvanced lines of credit:	18.9	44.6
Forward commitments to sell residential mortgage loans
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	0.7	25.4
Interest rate-lock commitments on residential mortgage loans
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	0.7	41.5
Stand-By Letters of Credit
Derivative Instruments And Hedging Activities [Line Items]
Letters of credit:	156	150.4
Commercial Letters of Credit
Derivative Instruments And Hedging Activities [Line Items]
Letters of credit:	4.2	4.5
Interest rate swaps | Subordinated Notes
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	925	925
Interest rate swaps | Customer
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	8,469.9	8,878.6
Interest rate swaps | Institutional counterparties
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	8,478.3	8,881.3
Interest rate caps | Customer
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	163.7	185.1
Interest rate caps | Institutional counterparties
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	163.7	185.1
Risk participation agreements
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	903.2	924.3
Foreign exchange contracts
Derivative Instruments And Hedging Activities [Line Items]
Derivative Financial Instruments	$ 321.8	$ 285.3

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Average period extended for letter of credit	1 year
Loan commitments and letters of credit	$ 28,400,000	$ 26,900,000
Net liability position, derivative instruments	0
Net unrealized gains (losses) arising during the year	1,200,000	(1,400,000)	$ 1,900,000
Interest rate swaps | Subordinated Notes
Derivative [Line Items]
Notional Amounts	925,000,000	925,000,000
Interest rate swaps | Fair Value
Derivative [Line Items]
Subordinated notes	400,000,000
Notional Amounts	$ 375,000,000
Basis points	1.265%
Interest rate swaps | Cash Flow | Federal Home Loan Bank Certificates and Obligations (FHLB) | Derivatives Designated as Hedging Instruments:
Derivative [Line Items]
Notional Amounts	$ 550,000,000	$ 550,000,000
Treasury Forward Interest Rate Locks ("T-Locks")
Derivative [Line Items]
Period hedged items affected earnings, years	10 years
Net unrealized gains (losses) arising during the year	$ 900,000
Total unrecognized gain	100,000
Treasury Forward Interest Rate Locks ("T-Locks") | Subordinated Notes
Derivative [Line Items]
Senior notes issuance	$ 500,000,000

Financial Instruments - Schedul

Financial Instruments - Schedule of Notional Amounts and Fair Values of Derivatives Outstanding (Detail) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Financial assets	$ 27,000,000	$ 18,600,000
Financial assets	388,100,000	800,300,000
Financial liabilities	79,000,000	168,600,000
Financial liabilities	95,300,000	170,400,000
Forward commitments to sell residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	700,000	25,400,000
Interest rate-lock commitments on residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	700,000	41,500,000
Derivatives Not Designated as Hedging Instruments:
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Financial assets	388,100,000	800,300,000
Financial liabilities	95,300,000	170,400,000
Derivatives Not Designated as Hedging Instruments: | Forward commitments to sell residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	700,000	25,400,000
Financial assets	0	700,000
Financial liabilities	0	0
Derivatives Not Designated as Hedging Instruments: | Forward commitments to sell residential mortgage loans | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Financial assets	100,000
Financial liabilities	100,000
Derivatives Not Designated as Hedging Instruments: | Interest rate-lock commitments on residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	700,000	41,500,000
Financial assets	0	0
Financial liabilities	0	1,000,000
Derivatives Not Designated as Hedging Instruments: | Interest rate-lock commitments on residential mortgage loans | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Financial assets	100,000
Financial liabilities	100,000
Derivatives Designated as Hedging Instruments:
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Financial assets	0	0
Financial liabilities	0	0
Interest rate swaps | Fair Value
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	375,000,000
Interest rate swaps | Derivatives Not Designated as Hedging Instruments: | Commercial customers
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	8,469,900,000	8,878,600,000
Financial assets	359,700,000	778,000,000
Financial liabilities	15,800,000	400,000
Interest rate swaps | Derivatives Not Designated as Hedging Instruments: | Institutional counterparties
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	8,478,300,000	8,881,300,000
Financial assets	24,300,000	5,800,000
Financial liabilities	75,000,000	156,800,000
Interest rate swaps | Derivatives Designated as Hedging Instruments: | Cash Flow | Federal Home Loan Bank Certificates and Obligations (FHLB)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	550,000,000	550,000,000
Financial assets	0	0
Financial liabilities	0	0
Interest rate swaps | Derivatives Designated as Hedging Instruments: | Subordinated Notes | Fair Value
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	375,000,000	375,000,000
Financial assets	0	0
Financial liabilities	0	0
Interest rate caps | Derivatives Not Designated as Hedging Instruments: | Commercial customers
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	163,700,000	185,100,000
Financial assets	1,400,000	3,000,000
Financial liabilities	300,000	0
Interest rate caps | Derivatives Not Designated as Hedging Instruments: | Institutional counterparties
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	163,700,000	185,100,000
Financial assets	300,000	0
Financial liabilities	1,400,000	3,000,000
Risk participation agreements
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	903,200,000	924,300,000
Risk participation agreements | Derivatives Not Designated as Hedging Instruments:
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	903,200,000	924,300,000
Financial assets	0	0
Financial liabilities	200,000	400,000
Foreign exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	321,800,000	285,300,000
Financial assets	2,400,000	12,800,000
Financial liabilities	2,600,000	8,800,000
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments:
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amounts	321,800,000	285,300,000
Financial assets	2,400,000	12,800,000
Financial liabilities	$ 2,600,000	$ 8,800,000

Financial Instruments - Impact

Financial Instruments - Impact of Derivatives on Pre-Tax Income and Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	$ 15.1	$ 23.6	$ 24.2
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	1.2	(1.3)	1.9
Derivatives Not Designated as Hedging Instruments:
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	7.2	15.7	25
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Forward commitments to sell residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	(0.7)	0.3	0.3
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Interest rate-lock commitments on residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	1	(0.5)	(0.4)
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Interest rate swaps | Commercial customers
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	(236.3)	614.8	374.9
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Interest rate swaps | Institutional counterparties
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	241.1	(599.4)	(350.3)
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Interest rate caps | Commercial customers
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	(1.2)	1.4	1.4
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Interest rate caps | Institutional counterparties
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	1.8	(1.4)	(1.5)
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Foreign exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	1.4	1	1
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Not Designated as Hedging Instruments: | Risk participation agreements
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	0.1	(0.5)	(0.4)
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Designated as Hedging Instruments:
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	7.9	7.9	(0.8)
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	1.2	(1.3)	1.9
Derivatives Designated as Hedging Instruments: | Cash Flow | Interest rate-lock commitments on residential mortgage loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	0.1	0.1	0.1
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Designated as Hedging Instruments: | Interest rate swaps | Fair Value
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	9.7	5.9	0.3
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	0	0	0
Derivatives Designated as Hedging Instruments: | Interest rate swaps | Cash Flow
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pre-Tax Gain (Loss) Recognized in Earnings	(1.9)	1.9	(1.2)
Amount of Pre-Tax Gain (Loss) Recognized in AOCL	$ 1.2	$ (1.3)	$ 1.9

Balance Sheet Offsetting - Summ

Balance Sheet Offsetting - Summary of Gross Presentation, Financial Instruments that are Eligible for Offset in Consolidated Statement of Condition (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financial assets:
Gross Amount Recognized	$ 27	$ 18.6
Gross Amount Offset	0	0
Net Amount Presented	27	18.6
Gross amounts not offset, financial instruments	(4.1)	(0.4)
Gross amounts not offset, collateral	(0.4)	0
Net Amount	22.5	18.2
Financial liabilities:
Gross Amount Recognized	79	168.6
Gross Amount Offset	0	0
Net Amount Presented	79	168.6
Gross amounts not offset, financial instruments	(4.1)	(0.4)
Gross amounts not offset, collateral	(72)	(148.4)
Net Amount	2.9	19.8
Interest Rate Swaps/Caps
Financial assets:
Gross Amount Offset	0
Foreign exchange contracts
Financial assets:
Gross Amount Recognized	2.4	12.8
Gross Amount Offset	0	0
Net Amount Presented	2.4	12.8
Gross amounts not offset, financial instruments	0	0
Gross amounts not offset, collateral	0	0
Net Amount	2.4	12.8
Financial liabilities:
Gross Amount Recognized	2.6	8.8
Gross Amount Offset	0	0
Net Amount Presented	2.6	8.8
Gross amounts not offset, financial instruments	0	0
Gross amounts not offset, collateral	0	0
Net Amount	2.6	8.8
Counterparty A | Interest Rate Swaps/Caps
Financial assets:
Gross Amount Recognized	0.1	0
Gross Amount Offset	0	0
Net Amount Presented	0.1	0
Gross amounts not offset, financial instruments	(0.1)	0
Gross amounts not offset, collateral	0	0
Net Amount	0	0
Financial liabilities:
Gross Amount Recognized	2.3	5.6
Gross Amount Offset	0	0
Net Amount Presented	2.3	5.6
Gross amounts not offset, financial instruments	(0.1)	0
Gross amounts not offset, collateral	(2.2)	(5.6)
Net Amount	0	0
Counterparty B | Interest Rate Swaps/Caps
Financial assets:
Gross Amount Recognized	0	0
Gross Amount Offset	0	0
Net Amount Presented	0	0
Gross amounts not offset, financial instruments	0	0
Gross amounts not offset, collateral	0	0
Net Amount	0	0
Financial liabilities:
Gross Amount Recognized	3.6	7.1
Gross Amount Offset	0	0
Net Amount Presented	3.6	7.1
Gross amounts not offset, financial instruments	0	0
Gross amounts not offset, collateral	(3.6)	(7.1)
Net Amount	0	0
Counterparty C | Interest Rate Swaps/Caps
Financial assets:
Gross Amount Recognized	1.7	0.3
Gross Amount Offset	0	0
Net Amount Presented	1.7	0.3
Gross amounts not offset, financial instruments	(1.7)	(0.3)
Gross amounts not offset, collateral	0	0
Net Amount	0	0
Financial liabilities:
Gross Amount Recognized	28.8	56.6
Gross Amount Offset	0	0
Net Amount Presented	28.8	56.6
Gross amounts not offset, financial instruments	(1.7)	(0.3)
Gross amounts not offset, collateral	(27.1)	(56.3)
Net Amount	0	0
Counterparty D | Interest Rate Swaps/Caps
Financial assets:
Gross Amount Recognized	0.6	0
Gross Amount Offset	0	0
Net Amount Presented	0.6	0
Gross amounts not offset, financial instruments	(0.6)	0
Gross amounts not offset, collateral	0	0
Net Amount	0	0
Financial liabilities:
Gross Amount Recognized	9.6	21.4
Gross Amount Offset	0	0
Net Amount Presented	9.6	21.4
Gross amounts not offset, financial instruments	(0.6)	0
Gross amounts not offset, collateral	(8.7)	(10.4)
Net Amount	0.3	11
Counterparty E | Interest Rate Swaps/Caps
Financial assets:
Gross Amount Recognized	20	5.4
Gross Amount Offset		0
Net Amount Presented	20	5.4
Gross amounts not offset, financial instruments	0	0
Gross amounts not offset, collateral	0	0
Net Amount	20	5.4
Financial liabilities:
Gross Amount Recognized	0	0
Gross Amount Offset	0	0
Net Amount Presented	0	0
Gross amounts not offset, financial instruments	0	0
Gross amounts not offset, collateral	0	0
Net Amount	0	0
Other counterparties | Interest Rate Swaps/Caps
Financial assets:
Gross Amount Recognized	2.2	0.1
Gross Amount Offset	0	0
Net Amount Presented	2.2	0.1
Gross amounts not offset, financial instruments	(1.7)	(0.1)
Gross amounts not offset, collateral	(0.4)	0
Net Amount	0.1	0
Financial liabilities:
Gross Amount Recognized	32.1	69.1
Gross Amount Offset	0	0
Net Amount Presented	32.1	69.1
Gross amounts not offset, financial instruments	(1.7)	(0.1)
Gross amounts not offset, collateral	(30.4)	(69)
Net Amount	$ 0	$ 0

Balance Sheet Offsetting - Addi

Balance Sheet Offsetting - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
U.S. Treasury
Offsettting Assets and Liabilities [Line Items]
Fair value of treasury securities	$ 252.9	$ 258.7
Mortgage-Backed Securities
Offsettting Assets and Liabilities [Line Items]
Fair value of treasury securities	$ 258.9	$ 254.4

Balance Sheet Offsetting - Su_2

Balance Sheet Offsetting - Summary of Collateral Swaps (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total repurchase agreements
Total customer repurchase agreements	$ 395.2	$ 452.9	$ 409.1
Collateral Swaps
Total resale agreements
Gross Amount Recognized	250	250
Gross Amount Offset	(250)	(250)
Net Amount Presented	0	0
Total repurchase agreements
Gross Amount Recognized	250	250
Gross Amount Offset	(250)	(250)
Total customer repurchase agreements	$ 0	$ 0

Segment Information - Additiona

Segment Information - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2021segment	Dec. 31, 2021Segment	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of primary operating segments		3	3
Number of operating reportable segments | Segment			2
Non-interest income	$ 72.3			$ 112.1	$ 123.5
Other
Segment Reporting Information [Line Items]
Non-interest income	3.9			75.9	10.9
Other non-interest expense	$ 47.8			$ 45.9	$ 65.6

Segment Information - Selected

Segment Information - Selected Financial Information Business Segments (Detail) - USD ($) $ in Millions	Oct. 01, 2020	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Net interest income (loss)		$ 362	$ 370.3	$ 380.9	$ 385.9	$ 382.8	$ 391.4	$ 405.6	$ 396	$ 1,499.1	$ 1,575.8	$ 1,412.3
Provisions for credit losses		(6)	12.1	(40.8)	(13.6)	14.7	26.8	80.8	33.5	(48.3)	155.8	28.3
Total non-interest income		99.6	100.4	99	94.6	178.2	101.1	89.6	123.8	393.6	492.7	431.1
Total non-interest expense		277.7	289.2	305	311.9	646.4	293.6	304	320.1	1,183.8	1,564.1	1,162.7
Income before income tax expense		189.9	169.4	215.7	182.2	(100.1)	172.1	110.4	166.2	757.2	348.6	652.4
Income tax expense (note 14)		40	29.7	44.9	37.7	45.2	27.5	20.5	35.8	152.3	129	132
Net income		$ 149.9	$ 139.7	$ 170.8	$ 144.5	$ (145.3)	$ 144.6	$ 89.9	$ 130.4	604.9	219.6	520.4
Average total assets										64,253.1	61,038.1	51,658
Average total liabilities										56,550.1	53,226.3	44,586.7
Goodwill impairment (note 8)	$ 353									0	353	0
Commercial Banking
Segment Reporting Information [Line Items]
Goodwill impairment (note 8)											0
Retail Banking
Segment Reporting Information [Line Items]
Goodwill impairment (note 8)											353
Operating Segments
Segment Reporting Information [Line Items]
Net interest income (loss)										1,822.7	1,733.8	1,362.2
Provisions for credit losses										61.4	62.8	53
Total non-interest income										368.1	399.5	402.4
Total non-interest expense										1,103.8	1,487.9	1,048.9
Income before income tax expense										1,025.6	582.6	662.7
Income tax expense (note 14)										205.4	172.1	132.8
Net income										820.2	410.5	529.9
Average total assets										44,568.3	49,393.6	42,307.7
Average total liabilities										48,381.3	43,502.9	34,887.9
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income (loss)										1,145.1	1,098.9	807.1
Provisions for credit losses										52.9	52.8	44.1
Total non-interest income										172.4	217.3	206.5
Total non-interest expense										452	478.5	448.7
Income before income tax expense										812.6	784.9	520.8
Income tax expense (note 14)										162.8	144.7	104.3
Net income										649.8	640.2	416.5
Average total assets										33,644.4	35,946.3	29,746.8
Average total liabilities										19,466.3	16,524.6	11,490.2
Operating Segments | Retail Banking
Segment Reporting Information [Line Items]
Net interest income (loss)										677.6	634.9	555.1
Provisions for credit losses										8.5	10	8.9
Total non-interest income										195.7	182.2	195.9
Total non-interest expense										651.8	1,009.4	600.2
Income before income tax expense										213	(202.3)	141.9
Income tax expense (note 14)										42.6	27.4	28.5
Net income										170.4	(229.7)	113.4
Average total assets										10,923.9	13,447.3	12,560.9
Average total liabilities										28,915	26,978.3	23,397.7
Treasury
Segment Reporting Information [Line Items]
Net interest income (loss)										(317.8)	(118.5)	66.5
Provisions for credit losses										(0.1)	(0.3)	0
Total non-interest income										14.8	7.8	14.1
Total non-interest expense										2.4	3.7	13.8
Income before income tax expense										(305.3)	(114.1)	66.8
Income tax expense (note 14)										(61)	(19.8)	13.5
Net income										(244.3)	(94.3)	53.3
Average total assets										17,946.9	9,988.1	7,882.3
Average total liabilities										7,274.9	8,863.8	9,011.9
Other
Segment Reporting Information [Line Items]
Net interest income (loss)										(5.8)	(39.5)	(16.4)
Provisions for credit losses										(109.6)	93.3	(24.7)
Total non-interest income										10.7	85.4	14.6
Total non-interest expense										77.6	72.5	100
Income before income tax expense										36.9	(119.9)	(77.1)
Income tax expense (note 14)										7.9	(23.3)	(14.3)
Net income										29	(96.6)	(62.8)
Average total assets										1,737.9	1,656.4	1,468
Average total liabilities										$ 893.9	$ 859.6	$ 686.9

Parent Company Financial Info_3

Parent Company Financial Information - Condensed Statements of Condition (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Cash at bank subsidiary	$ 320.5	$ 477.3
Total cash and cash equivalents	10,589.3	4,243.3
Equity securities, at fair value	0	5.3
Goodwill	2,680.8	2,680.8	$ 3,065.5
Other assets	2,025.4	2,352.2
Total assets	64,642.4	63,091.8
Liabilities and Stockholders’ Equity:
Notes and debentures	992.8	1,009.6
Other liabilities	1,034.7	1,194.1
Total stockholders’ equity	7,901.8	7,602.8	$ 7,947.2	$ 6,533.9
Total liabilities and stockholders’ equity	64,642.4	63,091.8
People's United Financial, Inc.
Assets:
Cash at bank subsidiary	490.2	305.3
Total cash and cash equivalents	490.2	305.3
Equity securities, at fair value	0	5.3
Goodwill	203	203
Due from bank subsidiary	5.8	3.1
Other assets	0.2	62.2
Total assets	8,484.9	8,186.5
Liabilities and Stockholders’ Equity:
Notes and debentures	578.4	579.1
Other liabilities	4.7	4.6
Total stockholders’ equity	7,901.8	7,602.8
Total liabilities and stockholders’ equity	8,484.9	8,186.5
People's United Financial, Inc. | Bank Subsidiary
Assets:
Investments in subsidiaries:	7,775.6	7,600.3
People's United Financial, Inc. | Non Bank Subsidiaries
Assets:
Investments in subsidiaries:	$ 10.1	$ 7.3

Parent Company Financial Info_4

Parent Company Financial Information - Condensed Statements of Income (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Interest income	$ 384.2	$ 393.8	$ 406.3	$ 417	$ 421.5	$ 436.8	$ 457.6	$ 499.1	$ 1,601.3	$ 1,815	$ 1,881.1
Non-interest income									72.3	112.1	123.5
Expenses:
Interest on notes and debentures									28.8	31.8	34.9
Non-interest expense	277.7	289.2	305	311.9	646.4	293.6	304	320.1	1,183.8	1,564.1	1,162.7
Income tax expense (note 14)	40	29.7	44.9	37.7	45.2	27.5	20.5	35.8	152.3	129	132
Net income	$ 149.9	$ 139.7	$ 170.8	$ 144.5	$ (145.3)	$ 144.6	$ 89.9	$ 130.4	604.9	219.6	520.4
People's United Financial, Inc.
Revenues:
Interest income									0.1	0.3	0.4
Non-interest income									1.1	(0.8)	1.7
Total revenues									440.7	497.5	459.1
Expenses:
Interest on notes and debentures									21.7	21.7	19.2
Non-interest expense									20	8.5	14.1
Total expenses									41.7	30.2	33.3
Income before income tax benefit and subsidiaries undistributed income (distributions in excess of income)									399	467.3	425.8
Income tax expense (note 14)									(8.5)	(6.5)	(6.2)
Income before subsidiaries undistributed income (distributions in excess of income)									407.5	473.8	432
Subsidiaries undistributed income (distributions in excess of income)									197.4	(254.2)	88.4
Net income									604.9	219.6	520.4
People's United Financial, Inc. | Bank Subsidiary
Revenues:
Bank subsidiary									437	498	457
People's United Financial, Inc. | Non Bank Subsidiaries
Revenues:
Bank subsidiary									$ 2.5	$ 0	$ 0

Parent Company Financial Info_5

Parent Company Financial Information - Condensed Statements of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net income	$ 149.9	$ 139.7	$ 170.8	$ 144.5	$ (145.3)	$ 144.6	$ 89.9	$ 130.4	$ 604.9	$ 219.6	$ 520.4
Other comprehensive (loss) income, net of tax:
Total other comprehensive (loss) income, net of tax									(47.6)	77.7	89.9
Total comprehensive income									557.3	297.3	610.3
People's United Financial, Inc.
Condensed Financial Statements, Captions [Line Items]
Net income									604.9	219.6	520.4
Other comprehensive (loss) income, net of tax:
Net unrealized losses on derivatives accounted for as cash flow hedges									(0.1)	(0.1)	(0.1)
Other comprehensive (loss) income of bank subsidiary									(47.5)	77.8	90
Total other comprehensive (loss) income, net of tax									(47.6)	77.7	89.9
Total comprehensive income									$ 557.3	$ 297.3	$ 610.3

Parent Company Financial Info_6

Parent Company Financial Information - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities:
Net income	$ 604.9	$ 219.6	$ 520.4
Adjustments to reconcile net income to net cash provided by operating activities:
Net change in other assets and other liabilities	494.4	(494.3)	(466.7)
Net cash provided by operating activities	1,216.1	842.9	240.8
Cash Flows from Investing Activities:
Proceeds from sales of equity securities	6.4	2	1.6
Net cash provided by (used in) investing activities	3,989.6	(1,318)	(310.5)
Cash Flows from Financing Activities:
Cash dividends paid on common stock	(307.8)	(304.1)	(274.8)
Cash dividends paid on preferred stock	(14.1)	(14.1)	(14.1)
Common stock repurchases	(2.1)	(306.1)	(4.5)
Proceeds from stock options exercised	36.6	0.7	24.1
Net cash provided by (used in) financing activities	1,140.3	3,917.4	(61.3)
Net increase (decrease) in cash and cash equivalents	6,346	3,442.3	(131)
Cash and cash equivalents at beginning of year	4,243.3	801	932
Cash and cash equivalents at end of year	10,589.3	4,243.3	801
People's United Financial, Inc.
Cash Flows from Operating Activities:
Net income	604.9	219.6	520.4
Adjustments to reconcile net income to net cash provided by operating activities:
Subsidiaries (undistributed income) distributions in excess of income	(197.4)	254.2	(88.4)
Net change in other assets and other liabilities	58.4	(2.1)	(0.7)
Net cash provided by operating activities	465.9	471.7	431.3
Cash Flows from Investing Activities:
Proceeds from sales of equity securities	6.4	2	1.6
Net cash provided by (used in) investing activities	6.4	2	1.6
Cash Flows from Financing Activities:
Cash dividends paid on common stock	(307.8)	(304.1)	(274.8)
Cash dividends paid on preferred stock	(14.1)	(14.1)	(14.1)
Common stock repurchases	(2.1)	(306.1)	(4.5)
Proceeds from stock options exercised	36.6	0.7	24.1
Net cash provided by (used in) financing activities	(287.4)	(623.6)	(269.3)
Net increase (decrease) in cash and cash equivalents	184.9	(149.9)	163.6
Cash and cash equivalents at beginning of year	305.3	455.2	291.6
Cash and cash equivalents at end of year	$ 490.2	$ 305.3	$ 455.2

Selected Quarterly Financial _3

Selected Quarterly Financial Data - Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information [Line Items]
Interest and dividend income	$ 384.2	$ 393.8	$ 406.3	$ 417	$ 421.5	$ 436.8	$ 457.6	$ 499.1	$ 1,601.3	$ 1,815	$ 1,881.1
Interest expense	22.2	23.5	25.4	31.1	38.7	45.4	52	103.1	102.2	239.2	468.8
Net interest income	362	370.3	380.9	385.9	382.8	391.4	405.6	396	1,499.1	1,575.8	1,412.3
Provisions for credit losses	(6)	12.1	(40.8)	(13.6)	14.7	26.8	80.8	33.5	(48.3)	155.8	28.3
Net interest income after provisions for credit losses	368	358.2	421.7	399.5	368.1	364.6	324.8	362.5	1,547.4	1,420	1,384
Non-interest income	99.6	100.4	99	94.6	178.2	101.1	89.6	123.8	393.6	492.7	431.1
Non-interest expense	277.7	289.2	305	311.9	646.4	293.6	304	320.1	1,183.8	1,564.1	1,162.7
Income before income tax expense	189.9	169.4	215.7	182.2	(100.1)	172.1	110.4	166.2	757.2	348.6	652.4
Income tax expense (note 14)	40	29.7	44.9	37.7	45.2	27.5	20.5	35.8	152.3	129	132
Net income	149.9	139.7	170.8	144.5	(145.3)	144.6	89.9	130.4	604.9	219.6	520.4
Preferred stock dividend	3.5	3.5	3.5	3.5	3.5	3.5	3.5	3.5	14.1	14.1	14.1
Net income available to common shareholders	$ 146.4	$ 136.2	$ 167.3	$ 141	$ (148.8)	$ 141.1	$ 86.4	$ 126.9	$ 590.8	$ 205.5	$ 506.3
EPS:
Basic (in dollars per share)	$ 0.35	$ 0.32	$ 0.40	$ 0.34	$ (0.36)	$ 0.34	$ 0.21	$ 0.30	$ 1.40	$ 0.49	$ 1.28
Diluted (in dollars per share)	$ 0.34	$ 0.32	$ 0.39	$ 0.33	$ (0.35)	$ 0.34	$ 0.21	$ 0.30	$ 1.39	$ 0.49	$ 1.27
Common dividends paid	$ 77.4	$ 77.4	$ 77.3	$ 75.7	$ 75.6	$ 75.7	$ 75.5	$ 77.3	$ 307.8	$ 304.1	$ 274.8
Dividends paid per common share (in dollars per share)	$ 0.1825	$ 0.1825	$ 0.1825	$ 0.1800	$ 0.1800	$ 0.1800	$ 0.1800	$ 0.1775	$ 0.1825	$ 0.1800
Common dividend payout ratio	52.90%	56.80%	46.20%	53.70%	(50.80%)	53.60%	87.40%	60.90%	52.10%	148.00%	54.30%
Basic (in shares)	421,650	421,430	421,090	419,120	418,150	418,050	417,910	427,180	420,800	420,300	394,000
Diluted (in shares)	425,450	424,770	425,080	422,580	420,390	420,290	420,150	429,770	424,500	422,600	397,200
Maximum
EPS:
Stock price (in dollars per share)	$ 19.05	$ 18.08	$ 19.62	$ 19.40	$ 13.58	$ 12.36	$ 13.99	$ 17	$ 19.05	$ 13.58
Minimum
EPS:
Stock price (in dollars per share)	$ 16.20	$ 15.18	$ 16.75	$ 12.66	$ 9.98	$ 9.74	$ 9.37	$ 10.40	$ 16.20	$ 9.98