First Midwest Bancorp (ONBPP) 10-K 28 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 26, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Entity File Number	0-10967
Entity Registrant Name	First Midwest Bancorp, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-3161078
Entity Address, Address Line One	8750 West Bryn Mawr Avenue
Entity Address, Address Line Two	Suite 1300
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60631-3655
City Area Code	708
Local Phone Number	831-7483
Title of 12(b) Security	Common stock, $0.01 par value
Trading Symbol	FMBI
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Central Index Key	0000702325
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2,216,559,049
Entity Common Stock, Shares Outstanding		109,670,054
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Documents Incorporated by Reference	Portions of the Registrant's proxy statement for the 2020 Annual Meeting of Stockholders are incorporated by reference into Part III.

Consolidated Statements of Fina

Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 214,894	$ 211,189
Interest-bearing deposits in other banks	84,327	78,069
Equity securities, at fair value	42,136	30,806
Securities available-for-sale, at fair value	2,873,386	2,272,009
Securities held-to-maturity, at amortized cost (fair value 2019 – $21,234; 2018 – $9,871)	21,997	10,176
Federal Home Loan Bank ("FHLB") and Federal Reserve Bank ("FRB") stock, at cost	115,409	80,302
Loans	12,840,330	11,446,783
Allowance for loan losses	(108,022)	(102,219)
Net loans	12,732,308	11,344,564
Other real estate owned ("OREO")	8,750	12,821
Premises, furniture, and equipment, net	147,996	132,502
Investment in bank-owned life insurance ("BOLI")	296,351	296,733
Goodwill and other intangible assets	875,262	790,744
Accrued interest receivable and other assets	437,581	245,734
Total assets	17,850,397	15,505,649
Liabilities
Noninterest-bearing deposits	3,802,422	3,642,989
Interest-bearing deposits	9,448,856	8,441,123
Total deposits	13,251,278	12,084,112
Borrowed funds	1,658,758	906,079
Senior and subordinated debt	233,948	203,808
Accrued interest payable and other liabilities	335,620	256,652
Total liabilities	15,479,604	13,450,651
Stockholders' Equity
Common stock	1,204	1,157
Additional paid-in capital	1,211,274	1,114,580
Retained earnings	1,380,612	1,192,767
Accumulated other comprehensive loss, net of tax	(1,954)	(52,512)
Treasury stock, at cost	(220,343)	(200,994)
Total stockholders' equity	2,370,793	2,054,998
Total liabilities and stockholders' equity	17,850,397	15,505,649
Fair Value	$ 21,234	$ 9,871

Consolidated Statements of Fi_2

Consolidated Statements of Financial Condition (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Securities held-to-maturity, at fair value	$ 21,234	$ 9,871
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	120,415,000	115,672,000
Common stock, shares outstanding	109,972,000	106,375,000
Treasury stock, shares	10,443,000	9,297,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest Income
Loans	$ 617,632	$ 523,229	$ 463,331
Investment securities – taxable	66,292	49,409	35,569
Investment securities – tax-exempt	6,501	5,060	6,296
Other short-term investments	8,314	4,794	4,520
Total interest income	698,739	582,492	509,716
Interest Expense
Deposits	77,598	37,774	16,184
Borrowed funds	18,228	15,388	9,100
Senior and subordinated debt	14,431	12,708	12,428
Total interest expense	110,257	65,870	37,712
Net interest income	588,482	516,622	472,004
Provision for loan losses	44,027	47,854	31,290
Net interest income after provision for loan losses	544,455	468,768	440,714
Noninterest Income
Service charges on deposit accounts	49,424	48,715	48,368
Wealth management fees	48,337	43,512	41,321
Card-based fees	18,133	17,024	28,992
Capital market products income	13,931	7,721	8,171
Mortgage banking income	10,105	7,094	8,131
Merchant servicing fees	1,423	1,465	10,340
Other service charges, commissions, and fees	9,940	9,425	9,843
Net securities losses	0	0
Net securities losses			(1,876)
Other income	11,586	9,636	9,859
Total noninterest income	162,879	144,592	163,149
Noninterest Expense
Salaries and wages	197,640	181,164	182,507
Retirement and other employee benefits	42,879	43,104	41,886
Net occupancy and equipment expense	56,334	53,434	49,751
Professional services	39,941	32,681	33,689
Technology and related costs	19,758	19,220	18,068
Advertising and promotions	11,561	9,248	8,694
Amortization of other intangible assets	10,481	7,444	7,865
Federal Deposit Insurance Corporation Premium ("FDIC") Expense	8,353	10,584	8,987
Net OREO expense	2,436	1,162	4,683
Merchant card expense	0	0	8,377
Cardholder expense	0	0	7,323
Other expenses	28,995	28,236	23,956
Acquisition and integration related expenses	21,860	9,613	20,123
Delivering Excellence implementation costs	1,157	20,413	0
Total noninterest expense	441,395	416,303	415,909
Income before income tax expense	265,939	197,057	187,954
Income tax expense	66,201	39,187	89,567
Net income	$ 199,738	$ 157,870	$ 98,387
Per Common Share Data
Basic earnings per common share (EPS) (in dollars per share)	$ 1.83	$ 1.52	$ 0.96
Diluted earnings per common share (in dollars per share)	$ 1.82	$ 1.52	$ 0.96
Weighted-average common shares outstanding (in shares)	108,156	102,850	101,423
Weighted-average diluted common shares outstanding (in shares)	108,584	102,854	101,443

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 199,738	$ 157,870	$ 98,387
Unrealized holding gains (losses):
Before tax	61,818	(16,294)	12,641
Tax effect	(17,218)	4,342	(5,077)
Net of tax	44,600	(11,952)	7,564
Reclassification of net losses included in net income:
Before tax	0	0	(1,876)
Tax effect	0	0	771
Net of tax	0	0	(1,105)
Net unrealized holding gains (losses)	44,600	(11,952)	8,669
Derivative Instruments
Before tax	4,670	2,786
Before tax			(4,333)
Tax effect	(1,301)	(789)
Tax effect			1,746
Net of tax	3,369	1,997
Net of tax			(2,587)
Net unrealized holding gains (losses):
Before tax	3,624	(3,850)	2,988
Tax effect	(1,035)	1,018	(1,196)
Net of tax	2,589	(2,832)	1,792
Total other comprehensive income (loss)	50,558	(12,787)	7,874
Total comprehensive income	$ 250,296	$ 145,083	$ 106,261

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income - AOCI - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		$ 2,054,998	$ 1,864,874	$ 1,257,080
Other comprehensive (loss) income		50,558	(12,787)	7,874
Adjustments to apply recent accounting pronouncements	[1]				$ 0
Ending balance		2,370,793	2,054,998	1,864,874
Accumulated Unrealized Loss on Securities Available- for-Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(28,792)	(13,976)	(22,645)
Other comprehensive (loss) income		44,600	(11,952)	8,669
Adjustments to apply recent accounting pronouncements	[1]				(2,864)
Ending balance		15,808	(28,792)	(13,976)
Accumulated Unrealized Loss on Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(3,763)	(1,176)
Other comprehensive (loss) income			1,997	(2,587)
Adjustments to apply recent accounting pronouncements	[1]				(784)
Ending balance				(3,763)
Accumulated Unrealized Loss on Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(2,550)
Other comprehensive (loss) income		3,369
Ending balance		819	(2,550)
Unrecognized Net Pension Costs
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(21,170)	(15,297)	(17,089)
Other comprehensive (loss) income		2,589	(2,832)	1,792
Adjustments to apply recent accounting pronouncements	[1]				(3,041)
Ending balance		(18,581)	(21,170)	(15,297)
Total Accumulated Other Comprehensive Loss, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(52,512)	(33,036)	(40,910)
Other comprehensive (loss) income		50,558	(12,787)	7,874
Adjustments to apply recent accounting pronouncements	[1]				$ (6,689)
Ending balance		$ (1,954)	$ (52,512)	$ (33,036)
[1]	As a result of accounting guidance adopted in 2018, certain reclassifications were made from accumulated other comprehensive loss to retained earnings as of January 1, 2018. For further discussion of this guidance, see Note 2. "Recent Accounting Pronouncements." (2) As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders’ Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2016		81,325
Beginning balance at Dec. 31, 2016	$ 1,257,080	$ 913	$ 498,937	$ 1,016,674	$ (40,910)	$ (218,534)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	98,387			98,387
Other comprehensive (loss) income	7,874				7,874
Common dividends declared ($0.39, $0.45 and $0.54)	(40,071)			(40,071)
Acquisition, net of issuance costs (in shares)		21,078
Acquisition, net of issuance costs	534,090	$ 210	533,322			558
Common stock issued (in shares)		9
Common stock issued	240		240
Restricted stock activity (in shares)		317
Restricted stock activity	(3,659)		(11,855)			8,196
Treasury stock issued to benefit plans (in shares)		(12)
Treasury stock issued to benefit plans	(290)		3			(293)
Share-based compensation expense	11,223		11,223
Ending balance (in shares) at Dec. 31, 2017		102,717
Ending balance at Dec. 31, 2017	1,864,874	$ 1,123	1,031,870	1,074,990	(33,036)	(210,073)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common dividends declared per common share (in dollars per share)		$ 0.39
Net income	157,870			157,870
Other comprehensive (loss) income	(12,787)				(12,787)
Common dividends declared ($0.39, $0.45 and $0.54)	(46,782)			(46,782)
Acquisition, net of issuance costs (in shares)		3,311
Acquisition, net of issuance costs	83,303	$ 33	83,270			0
Common stock issued (in shares)		39
Common stock issued	961	$ 1	293			667
Restricted stock activity (in shares)		311
Restricted stock activity	(4,421)		(12,983)			8,562
Treasury stock issued to benefit plans (in shares)		(3)
Treasury stock issued to benefit plans	(82)		68			(150)
Share-based compensation expense	$ 12,062		12,062
Ending balance (in shares) at Dec. 31, 2018	106,375	106,375
Ending balance at Dec. 31, 2018	$ 2,054,998	$ 1,157	1,114,580	1,192,767	(52,512)	(200,994)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common dividends declared per common share (in dollars per share)		$ 0.45
Net income	199,738			199,738
Other comprehensive (loss) income	50,558				50,558
Common dividends declared ($0.39, $0.45 and $0.54)	(59,150)			(59,150)
Acquisition, net of issuance costs (in shares)		4,879
Acquisition, net of issuance costs	101,496	$ 47	97,350			4,099
Common stock issued (in shares)		38
Common stock issued	$ 762		88			674
Common stock repurchased (in shares)	1,700	(1,687)
Repurchases of common stock	$ (33,928)					(33,928)
Restricted stock activity (in shares)		381
Restricted stock activity	(3,830)		(13,913)			10,083
Treasury stock issued to benefit plans (in shares)		(14)
Treasury stock issued to benefit plans	(291)		(14)			(277)
Share-based compensation expense	$ 13,183		13,183
Ending balance (in shares) at Dec. 31, 2019	109,972	109,972
Ending balance at Dec. 31, 2019	$ 2,370,793	$ 1,204	$ 1,211,274	$ 1,380,612	$ (1,954)	$ (220,343)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common dividends declared per common share (in dollars per share)		$ 0.54

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders’ Equity (Parentheticals) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common dividends declared per common share (in dollars per share)	$ 0.14	$ 0.14	$ 0.14	$ 0.12	$ 0.12	$ 0.11	$ 0.11	$ 0.11	$ 0.10	$ 0.10	$ 0.10	$ 0.09
Common Stock
Common dividends declared per common share (in dollars per share)													$ 0.54	$ 0.45	$ 0.39

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income		$ 199,738	$ 157,870	$ 98,387
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses		44,027	47,854	31,290
Depreciation of premises, furniture, and equipment		16,366	15,865	13,995
Net amortization of premium on securities		15,731	15,348	16,142
Net securities losses		0	0
Net securities losses				1,876
Gains on sales of 1-4 family mortgages and corporate loans held-for-sale		(9,992)	(5,562)	(7,078)
Net losses (gains) on sales and valuation adjustments of OREO		373	(347)	585
Amortization of the FDIC indemnification asset		1,208	1,208	1,208
Net losses (gains) on sales and valuation adjustments of premises, furniture, and equipment		879	5,227	(125)
BOLI income		(8,394)	(5,835)	(5,946)
Net pension (income) cost		(489)	1,447	981
Share-based compensation expense	[1]	13,183	12,062	11,223
Tax benefit related to share-based compensation		364	258	349
Provision for deferred income tax expense (benefit)		10,944	26,309	(4,077)
Amortization of other intangible assets		10,481	7,444	7,865
Originations of mortgage loans held-for-sale		(499,318)	(224,303)	(254,030)
Proceeds from sales of mortgage loans held-for-sale		474,384	245,967	258,626
Net (increase) decrease in equity securities		(4,364)	964	0
Net increase in trading securities		0	0	(2,527)
Net (increase) decrease in accrued interest receivable and other assets		(146,968)	(44,246)	121,577
Net increase (decrease) in accrued interest payables and other liabilities		108,956	(4,346)	(56,055)
Net cash provided by operating activities		227,109	253,184	234,266
Investing Activities
Proceeds from maturities, repayments, and calls of securities available-for-sale		531,032	331,026	349,444
Proceeds from sales of securities available-for-sale		93,332	24,974	629,843
Purchases of securities available-for-sale		(916,564)	(735,701)	(733,440)
Proceeds from maturities, repayments, and calls of securities held-to-maturity		4,460	3,584	8,546
Purchases of securities held-to-maturity		(2,855)	0	(15)
Net purchases of FHLB stock		(33,626)	(10,040)	(7,330)
Net increase in loans		(719,676)	(770,039)	(457,501)
Proceeds from claims on BOLI, net of premiums paid		8,776		1,722
Proceeds from claims on BOLI, net of premiums paid			(49)
Proceeds from sales of OREO		10,645	16,953	19,326
Proceeds from sales of premises, furniture, and equipment		4,145	4,561	18,031
Purchases of premises, furniture, and equipment		(20,330)	(27,800)	(16,123)
Net cash (paid for) received from acquisitions		(13,532)
Net cash (paid for) received from acquisitions			160,145	41,717
Net cash used in investing activities		(1,054,193)	(1,002,386)	(145,780)
Financing Activities
Net increase in deposit accounts		180,412	567,627	200,848
Net increase (decrease) in borrowed funds		750,933	172,977
Net increase (decrease) in borrowed funds				(164,124)
Repurchases of common stock		33,928	0	0
Cash dividends paid		(56,540)	(44,293)	(37,129)
Restricted stock activity		(3,830)	(4,421)	(3,659)
Net cash provided by (used in) financing activities		837,047	691,890	(4,064)
Net increase (decrease) in cash and cash equivalents		9,963	(57,312)	84,422
Cash and cash equivalents at beginning of year		289,258	346,570	262,148
Cash and cash equivalents at end of year		299,221	289,258	346,570
Supplemental Disclosures of Cash Flow Information:
Income taxes paid (refunded)		48,899	(1,108)	15,191
Interest paid to depositors and creditors		109,760	60,569	36,424
Dividends declared, but unpaid		15,283	12,674	10,185
Common stock issued for acquisitions, net of issuance costs		101,496	83,303	534,090
Non-cash transfers of loans to OREO		944	6,027	6,255
Non-cash transfers of loans to other assets		13,175	0	0
Non-cash transfers of loans held-for-investment to loans held-for-sale		9,472	15,060	48,999
Non-cash transfer of trading securities and securities available-for-sale to equity securities		0	$ 27,855	$ 0
Non-cash recognition of right-of-use asset		$ 143,561
[1]	Comprised of restricted stock, restricted stock unit, and performance share awards expense.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations – First Midwest Bancorp, Inc. (the "Company") is a bank holding company that was incorporated in Delaware in 1982 and began operations on March 31, 1983. The Company is headquartered in Chicago, Illinois with operations throughout metropolitan Chicago, southeast Wisconsin, northwest Indiana, central and western Illinois, and eastern Iowa. The Company operates three wholly-owned subsidiaries: First Midwest Bank (the "Bank"), Northern Oak Wealth Management, Inc. ("Northern Oak"), and Premier Asset Management LLC ("Premier"). The Bank conducts the majority of the Company's operations and Northern Oak and Premier are registered investment advisers providing advisory services to certain of the Company's wealth management clients. The Company is engaged in commercial and consumer banking and offers a full range of commercial, treasury management, equipment leasing, consumer, wealth management, trust, and private banking products and services. Basis of Presentation – The accounting and reporting policies of the Company and its subsidiaries conform to U.S. generally accepted accounting principles ("GAAP") and general practices within the banking industry. Certain reclassifications were made to prior year amounts to conform to the current year presentation. Use of Estimates – The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Although these estimates and assumptions are based on the best available information, actual results could differ from those estimates. Principles of Consolidation – The accompanying consolidated financial statements include the financial position and results of operations of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. Assets held in a fiduciary or agency capacity are not assets of the Company or its subsidiaries and are not included in the consolidated financial statements. Segment Disclosures – The Company has one reportable segment. The Company's chief operating decision maker evaluates the operations of the Company using consolidated information for purposes of allocating resources and assessing performance. Therefore, segment disclosures are not required. The following is a summary of the Company's significant accounting policies. Business Combinations – Business combinations are accounted for under the acquisition method of accounting. Assets acquired and liabilities assumed are recorded at their estimated fair values as of the date of acquisition, with any excess of the purchase price of the acquisition over the fair value of the identifiable net tangible and intangible assets acquired recorded as goodwill. Alternatively, a gain is recorded if the fair value of assets purchased exceeds the fair value of liabilities assumed and consideration paid. The results of operations of the acquired business are included in the Consolidated Statements of Income from the effective date of the acquisition. Cash and Cash Equivalents – For purposes of the Consolidated Statements of Cash Flows, management defines cash and cash equivalents to include cash and due from banks, interest-bearing deposits in other banks, and other short-term investments, if any, such as federal funds sold and securities purchased under agreements to resell. Securities – Securities are classified as held-to-maturity, equity, or available-for-sale at the time of purchase. Securities Held-to-Maturity – Securities classified as held-to-maturity are securities for which management has the intent and ability to hold to maturity. These securities are stated at cost and adjusted for amortization of premiums and accretion of discounts over the estimated lives of the securities using the effective interest method. Equity Securities – The Company's equity securities consist primarily of community development investments and certain diversified investment securities held in a grantor trust for participants in the Company's nonqualified deferred compensation plan that are invested in money market and mutual funds. These securities are carried at fair value with changes in fair value recognized in net income. Securities Available-for-Sale – All other securities are classified as available-for-sale. Securities available-for-sale are carried at fair value with unrealized gains and losses, net of related deferred income taxes, recorded in stockholders' equity as a separate component of accumulated other comprehensive loss. The historical cost of debt securities is adjusted for amortization of premiums and accretion of discounts over the estimated life of the security using the effective interest method. Amortization of premiums and accretion of discounts are included in interest income. Purchases and sales of securities are recognized on a trade date basis. Realized securities gains or losses are reported in net securities losses in the Consolidated Statements of Income. The cost of securities sold is based on the specific identification method. On a quarterly basis, the Company individually assesses securities with unrealized losses to determine whether there were any events or circumstances indicating that an other-than-temporary impairment ("OTTI") has occurred. In evaluating OTTI, the Company considers many factors, including (i) the severity and duration of the impairment, (ii) the financial condition and near-term prospects of the issuer, including external credit ratings and recent downgrades for debt securities, (iii) its intent to hold the security until its value recovers, and (iv) the likelihood that it will be required to sell the security before a recovery in value, which may be at maturity. If management intends to sell the security or believes it is more likely than not that it will be required to sell the security prior to full recovery, an OTTI charge will be recognized through income as a realized loss and included in net securities losses in the Consolidated Statements of Income. If management does not expect to sell the security or believes it is not more likely than not that it will be required to sell the security prior to full recovery, the OTTI is separated into the amount related to credit deterioration, which is recognized through income as a realized loss, and the amount resulting from other factors, which is recognized in other comprehensive income. FHLB and FRB Stock – The Company, as a member of the FHLB and FRB, is required to maintain an investment in the capital stock of the FHLB and FRB. No ready market exists for these stocks, and they have no quoted market values. The stock is redeemable at par by the FHLB and FRB and is, therefore, carried at cost and periodically evaluated for impairment. Loans – Loans held-for-investment are loans that the Company intends to hold until they are paid in full and are carried at the principal amount outstanding, including certain net deferred loan origination fees. Loan origination fees, commitment fees, and certain direct loan origination costs are deferred, and the net amount is amortized as a yield adjustment over the contractual life of the related loans or commitments and included in interest income. Fees related to letters of credit are amortized into fee income over the contractual life of the commitment. Other credit-related fees are recognized as fee income when earned. The Company's net investment in direct financing leases is included in loans and consists of future minimum lease payments and estimated residual values, net of unearned income. Interest income on loans is accrued based on principal amounts outstanding. Loans held-for-sale are carried at the lower of aggregate cost or fair value and included in other assets in the Consolidated Statements of Financial Condition. Acquired and Covered Loans – Covered loans consist of loans acquired by the Company in Federal Deposit Insurance Corporation ("FDIC")-assisted transactions, which are covered by loss share agreements with the FDIC (the "FDIC Agreements"), under which the FDIC reimburses the Company for the majority of the losses and eligible expenses related to these assets during the coverage period. Acquired loans consist of all other loans that were acquired in business combinations that are not covered by the FDIC Agreements. Certain loans that were previously classified as covered loans are no longer covered under the FDIC Agreements, and are included in acquired loans. Covered loans and acquired loans are included within loans held-for-investment. Acquired and covered loans are separated into (i) non-purchased credit impaired ("non-PCI") and (ii) purchased credit impaired ("PCI") loans. Non-PCI loans include loans that did not have evidence of credit deterioration since origination at the acquisition date. PCI loans include loans that had evidence of credit deterioration since origination and for which it was probable at acquisition that the Company would not collect all contractually required principal and interest payments. Evidence of credit deterioration was evaluated using various indicators, such as past due and non-accrual status. Leases and revolving loans do not qualify to be accounted for as PCI loans and are accounted for as non-PCI loans. The acquisition adjustment related to non-PCI loans is amortized into interest income over the contractual life of the related loans. If an acquired non-PCI loan is renewed subsequent to the acquisition date, any remaining acquisition adjustment is accreted into interest income and the loan is considered a new loan that is no longer classified as an acquired loan. PCI loans are accounted for based on estimates of expected future cash flows. To estimate the fair value, the Company generally aggregates purchased consumer loans and commercial loans into pools of loans with common risk characteristics, such as delinquency status, credit score, and internal risk ratings. The fair values of larger balance commercial loans are estimated on an individual basis. The Company use a discounted cash flow analysis involving significant unobservable inputs and assumptions to measure the fair value of PCI loans. The significant assumptions utilized in the cash flow analysis include the probability of default ("PD"), loss given default ("LGD"), and discount rate. Expected future cash flows in excess of the fair value of loans at the purchase date ("accretable yield") are recorded as interest income over the life of the loans if the timing and amount of the expected future cash flows can be reasonably estimated. The non-accretable yield represents the difference between contractually required payments and the expected future cash flows determined at acquisition. Subsequent increases in expected future cash flows are offset against the allowance for credit losses to the extent an allowance has been established or otherwise recognized as interest income prospectively. The present value of any decreases in expected future cash flows is recognized by recording a charge-off through the allowance for loan losses or providing an allowance for loan losses. 90-Days Past Due Loans – The Company's accrual of interest on loans is generally discontinued at the time the loan is 90 days past due unless the credit is sufficiently collateralized and in the process of renewal or collection. Non-accrual Loans – Generally, corporate loans are placed on non-accrual status (i) when either principal or interest payments become 90 days or more past due unless the credit is sufficiently collateralized and in the process of renewal or collection, or (ii) when an individual analysis of a borrower's creditworthiness warrants a downgrade to non-accrual regardless of past due status. When a loan is placed on non-accrual status, unpaid interest credited to income in the current year is reversed, and unpaid interest accrued in prior years is charged against the allowance for loan losses. After the loan is placed on non-accrual status, all debt service payments are applied to the principal on the loan. Future interest income may only be recorded on a cash basis after recovery of principal is reasonably assured. Non-accrual loans are returned to accrual status when the financial position of the borrower and other relevant factors indicate that the Company will collect all principal and interest. Commercial loans and loans secured by real estate are charged-off when deemed uncollectible. A loss is recorded if the net realizable value of the underlying collateral is less than the outstanding principal and interest. Consumer loans that are not secured by real estate are subject to mandatory charge-off at a specified delinquency date and are usually not classified as non-accrual prior to being charged-off. Closed-end consumer loans, which include installment, consumer secured, and single payment loans, are usually charged-off no later than the end of the month in which the loan becomes 120 days past due. PCI loans are generally considered accruing loans unless reasonable estimates of the timing and amount of expected future cash flows cannot be determined. Loans without reasonable future cash flow estimates are classified as non-accrual loans, and interest income is not recognized on those loans until the timing and amount of the expected future cash flows can be reasonably determined. Troubled Debt Restructurings ("TDRs") – A restructuring is considered a TDR when (i) the borrower is experiencing financial difficulties, and (ii) the creditor grants a concession, such as forgiveness of principal, reduction of the interest rate, changes in payments, or extension of the maturity date. Loans are not classified as TDRs when the modification is short-term or results in an insignificant delay in payments. The Company's TDRs are determined on a case-by-case basis. The Company does not accrue interest on a TDR unless it believes collection of all principal and interest under the modified terms is reasonably assured. For a TDR to begin accruing interest, the borrower must demonstrate some level of past performance and the future capacity to perform under the modified terms. Generally, six months of consecutive payment performance under the restructured terms is required before a TDR is returned to accrual status. However, the period could vary depending on the individual facts and circumstances of the loan. An evaluation of the borrower's current creditworthiness is used to assess the borrower's capacity to repay the loan under the modified terms. This evaluation includes an estimate of expected future cash flows, evidence of strong financial position, and estimates of the value of collateral, if applicable. For TDRs to be removed from TDR status in the calendar year after the restructuring, the loans must (i) have an interest rate and terms that reflect market conditions at the time of restructuring, and (ii) be in compliance with the modified terms. If the loan was restructured at below market rates and terms, it continues to be separately reported as a TDR until it is paid in full or charged-off. Impaired Loans – Impaired loans consist of corporate non-accrual loans and TDRs. A loan is considered impaired when it is probable that the Company will not collect all contractual principal and interest. With the exception of accruing TDRs, impaired loans are classified as non-accrual and are exclusive of smaller homogeneous loans, such as home equity, 1-4 family mortgages, and installment loans. Impaired loans with balances under a specified threshold are not individually evaluated for impairment. For all other impaired loans, impairment is measured by comparing the estimated value of the loan to the recorded book value. The value of collateral-dependent loans is based on the fair value of the underlying collateral, less costs to sell. The value of other loans is measured using the present value of expected future cash flows discounted at the loan's initial effective interest rate. Allowance for Credit Losses – The allowance for credit losses is comprised of the allowance for loan losses and the reserve for unfunded commitments, and is maintained by management at a level believed adequate to absorb estimated losses inherent in the existing loan portfolio. Determination of the allowance for credit losses is subjective since it requires significant estimates and management judgment, including the amounts and timing of expected future cash flows on impaired loans, estimated losses on pools of homogeneous loans, consideration of current economic trends, and other factors. Loans deemed to be uncollectible are charged-off against the allowance for loan losses, while recoveries of amounts previously charged-off are credited to the allowance for loan losses. Additions to the allowance for loan losses are charged to expense through the provision for loan losses. The amount of provision depends on a number of factors, including net charge-off levels, loan growth, changes in the composition of the loan portfolio, and the Company's assessment of the allowance for loan losses based on the methodology discussed below. Allowance for Loan Losses – The allowance for loan losses consists of (i) specific reserves for individual loans where the recorded investment exceeds the value, (ii) an allowance based on a loss migration analysis that uses historical credit loss experience for each loan category, and (iii) an allowance based on other internal and external qualitative factors. The specific reserves component of the allowance for loan losses is based on a periodic analysis of impaired loans exceeding a fixed dollar amount. If the value of an impaired loan is less than the recorded book value, the Company either establishes a valuation allowance (i.e., a specific reserve) equal to the excess of the book value over the collateral value of the loan as a component of the allowance for loan losses or charges off the amount if it is a confirmed loss. The general reserve component is based on a loss migration analysis, which examines actual loss experience by loan category for a rolling 8-quarter period and the related internal risk rating for corporate loans. The loss migration analysis is updated quarterly primarily using actual loss experience. This component is then adjusted based on management's consideration of many internal and external qualitative factors, including: • Changes in the composition of the loan portfolio, trends in the volume of loans, and trends in delinquent and non-accrual loans that could indicate that historical trends do not reflect current conditions. • Changes in credit policies and procedures, such as underwriting standards and collection, charge-off, and recovery practices. • Changes in the experience, ability, and depth of credit management and other relevant staff. • Changes in the quality of the Company's loan review system and Board of Directors oversight. • The effect of any concentration of credit and changes in the level of concentrations, such as loan type or risk rating. • Changes in the value of the underlying collateral for collateral-dependent loans. • Changes in the national and local economy that affect the collectability of various segments of the portfolio. • The effect of other external factors, such as competition and legal and regulatory requirements, on the Company's loan portfolio. The allowance for loan losses also consists of an allowance on acquired and covered non-PCI and PCI loans. No allowance for loan losses is recorded on acquired loans at the acquisition date. Subsequent to the acquisition date, an allowance for credit losses is established as necessary to reflect credit deterioration. The acquired non-PCI allowance is based on management's evaluation of the acquired non-PCI loan portfolio giving consideration to the current portfolio balance, including the remaining acquisition adjustments, maturity dates, and overall credit quality. The allowance for covered non-PCI loans is calculated in the same manner as the general reserve component based on a loss migration analysis as discussed above. The acquired and covered PCI allowance reflects the difference between the carrying value and the discounted expected future cash flows of the acquired and covered PCI loans. On a periodic basis, the adequacy of this allowance is determined through a re-estimation of expected future cash flows on all of the outstanding acquired and covered PCI loans using either a PD/LGD methodology or a specific review methodology. The PD/LGD model is a loss model that estimates expected future cash flows using a probability of default curve and loss given default estimates. Acquired non-PCI loans that have renewed subsequent to the respective acquisition dates are no longer classified as acquired loans. Instead, they are included in the general loan population and allocated an allowance based on a loss migration analysis. Reserve for Unfunded Commitments – The Company also maintains a reserve for unfunded commitments, including letters of credit, for the risk of loss inherent in these arrangements. The reserve for unfunded commitments is estimated using the loss migration analysis from the allowance for loan losses, adjusted for probabilities of future funding requirements. The reserve for unfunded commitments is included in other liabilities in the Consolidated Statements of Financial Condition. The establishment of the allowance for credit losses involves a high degree of judgment and estimation given the difficulty of assessing the factors impacting loan repayment and estimating the timing and amount of losses. While management utilizes its best judgment and information available, the adequacy of the allowance for credit losses depends on a variety of factors beyond the Company's control, including the performance of its loan portfolio, current national and local economic trends, changes in interest rates and property values, the amounts and timing of expected future cash flows on impaired loans, estimated losses on pools of homogeneous loans, the interpretation of loan risk classifications by regulatory authorities, and various internal and external qualitative factors. OREO – OREO consists of properties acquired through foreclosure in partial or total satisfaction of defaulted loans. At initial transfer into OREO, properties are recorded at fair value, less estimated selling costs. Subsequently, OREO is carried at the lower of the cost basis or fair value, less estimated selling costs. OREO write-downs occurring at the transfer date are charged against the allowance for loan losses, establishing a new cost basis. Subsequent to the initial transfer, the carrying values of OREO may be adjusted through a valuation allowance to reflect reductions in value resulting from new appraisals, new list prices, changes in market conditions, or changes in disposition strategies. Increases in value can be recognized through a reduction in the valuation allowance, but may not exceed the established cost basis. These valuation adjustments, along with expenses related to maintenance of the properties, are included in net OREO expense in the Consolidated Statements of Income. FDIC Indemnification Asset – The majority of loans and OREO acquired through FDIC-assisted transactions are covered by the FDIC Agreements, under which the FDIC reimburses the Company for the majority of the losses and eligible expenses related to these assets during the coverage period. The FDIC indemnification asset represents the present value of expected future reimbursements from the FDIC. Since the indemnified items are covered loans and covered OREO, which are initially measured at fair value, the FDIC indemnification asset is also initially measured at fair value by discounting the expected future cash flows to be received from the FDIC. These expected future cash flows are estimated by multiplying estimated losses on covered PCI loans and covered OREO by the reimbursement rates in the FDIC Agreements. The balance of the FDIC indemnification asset is adjusted periodically to reflect changes in expected future cash flows. Decreases in estimated reimbursements from the FDIC are recorded prospectively through amortization and increases in estimated reimbursements from the FDIC are recognized by an increase in the carrying value of the indemnification asset. Payments from the FDIC for reimbursement of losses result in a reduction of the FDIC indemnification asset. Depreciable Assets – Premises, furniture, and equipment are stated at cost, less accumulated depreciation. Depreciation expense is determined by the straight-line method over the estimated useful lives of the assets. Useful lives range from 3 to 10 years for furniture and equipment and 25 to 40 years for premises. Leasehold improvements are amortized over the shorter of the life of the asset or the lease term. Gains on dispositions are included in other noninterest income and losses on dispositions are included in other noninterest expense in the Consolidated Statements of Income. Maintenance and repairs are charged to operating expenses as incurred, while improvements that extend the useful life of assets are capitalized and depreciated over the estimated remaining life. Certain assets, such as buildings and land, that the Company intends to sell and meet held-for-sale criteria are transferred into the held-for-sale category at the lower of their fair value, as determined by a current appraisal, or their recorded investment. Long-lived depreciable assets are evaluated periodically for impairment when events or changes in circumstances indicate the carrying amount may not be recoverable. Impairment exists when the undiscounted expected future cash flows of a long-lived asset are less than its carrying value. In that event, the Company recognizes a loss for the difference between the carrying amount and the estimated fair value of the asset based on a quoted market price, if applicable, or a discounted cash flow analysis. Impairment losses are recorded in other noninterest expense in the Consolidated Statements of Income. BOLI – BOLI represents life insurance policies on the lives of certain Company directors and officers for which the Company is the sole owner and beneficiary. These policies are recorded as an asset in the Consolidated Statements of Financial Condition at their cash surrender value ("CSV") or the current amount that could be realized if settled. The change in CSV and insurance proceeds received are included as a component of noninterest income in the Consolidated Statements of Income. Goodwill and Other Intangible Assets – Goodwill represents the excess of the purchase price of the acquisition over the fair value of the net tangible and intangible assets acquired using the acquisition method of accounting. Goodwill is not amortized. Instead, impairment testing is conducted annually as of October 1 or more often if events or circumstances between annual tests indicate that there may be impairment. Impairment testing is performed using either a qualitative or quantitative approach at the reporting unit level. All of the Company's goodwill is allocated to First Midwest Bancorp, Inc., which is the Company's only applicable reporting unit for purposes of testing goodwill for impairment. Impairment testing performed using a qualitative approach assesses recent events and circumstances to determine whether it is more-likely-than-not that the fair value of a reporting unit is less than its carrying amount. Qualitative factors include, but are not limited to, macroeconomic conditions, industry- and market- specific conditions and trends, the Company's financial performance, market capitalization, stock price, and Company-specific events relevant to the assessment. If the assessment of qualitative factors indicates that it is not more-likely-than-not that an impairment exists, no further testing is performed; otherwise, the Company would proceed with a quantitative two-step goodwill impairment test. In the first step, the Company compares its estimate of the fair value of the reporting unit, which is based on a discounted cash flow analysis, with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired and the second step is not required. If necessary, the second step compares the implied fair value of the reporting unit goodwill with the carrying amount of that goodwill. The implied fair value of goodwill is determined by assigning the value of the reporting unit to all of the assets and liabilities of that unit, including any other identifiable intangible assets. An impairment loss is recognized if the carrying amount of the reporting unit goodwill exceeds the implied fair value of goodwill. Other intangible assets represent purchased assets that lack physical substance, but can be distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in combination with a related contract, asset, or liability. Identified intangible assets that have a finite useful life are amortized over that life in a manner that reflects the estimated decline in the economic value of the identified intangible asset. All of the Company's other intangible assets have finite lives and are amortized over varying periods not exceeding 10 years. Intangible assets are reviewed for impairment annually or more frequently when events or circumstances indicate that its carrying amount may not be recoverable. Wealth Management – Assets held in a fiduciary or agency capacity for customers are not included in the consolidated financial statements as they are not assets of the Company or its subsidiaries. Fee income is recognized on an accrual basis and is included as a component of noninterest income in the Consolidated Statements of Income. Derivative Financial Instruments – To provide derivative products to customers and in the ordinary course of business, the Company enters into derivative transactions as part of its overall interest rate risk management strategy to minimize significant unplanned fluctuations in earnings and expected future cash flows caused by interest rate volatility. All derivative instruments are recorded at fair value as either other assets or other liabilities in the Consolidated Statements of Financial Condition. Subsequent changes in a derivative's fair value are recognized in earnings unless specific hedge accounting criteria are met. On the date the Company enters into a derivative contract, the derivative is designated as a fair value hedge, a cash flow hedge, or a non-hedge derivative instrument. Fair value hedges are designed to mitigate exposure to changes in the fair value of an asset or liability attributable to a particular risk, such as interest rate risk. Cash flow hedges are designed to mitigate exposure to variability in expected future cash flows to be received or paid related to an asset, liability, or other type of forecasted transaction. The Company formally documents all relationships between hedging instruments and hedged items, including its risk management objective and strategy at inception. At the hedge's inception and quarterly thereafter, a formal assessment is performed to determine the effectiveness of the derivative in offsetting changes in the fair values or expected future cash flows of the hedged items in the current period and prospectively. If a derivative instrument designated as a hedge is terminated or ceases to be highly effective, hedge accounting is discontinued prospectively, and the gain or loss is amortized into earnings. For fair value hedges, the gain or loss is amortized over the remaining life of the hedged asset or liability. For cash flow hedges, the gain or loss is amortized over the same period that the forecasted hedged transactions impact earnings. If the hedged item is disposed of, any fair value adjustments are included in the gain or loss from the disposition of the hedged item. If the forecasted transaction is no longer probable, the gain or loss is included in earnings immediately. For fair value hedges, changes in the fair value of the derivative instruments, as well as changes in the fair value of the hedged item, are recognized in earnings. For cash flow hedges, the effective portion of the change in fair value of the derivative instrument is reported as a compone

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Adopted Accounting Pronouncements Leases: In February of 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02 to increase transparency and comparability across entities for leasing arrangements. This guidance requires lessees to recognize assets and liabilities for most leases. For lessors, this guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. In addition, this guidance clarifies criteria for the determination of whether a contract is or contains a lease. This guidance is effective for annual and interim periods beginning after December 15, 2018. The Company adopted this guidance on January 1, 2019, which resulted in the recognition of $143.6 million of right-of-use assets and additional associated lease liabilities for its operating leases. The amount of right-of-use assets and associated lease liabilities recorded upon adoption was based on the present value of future minimum lease payments, the amount of which depended on the population of leases in effect at the date of adoption. This guidance also applies to the Company's net investment in direct financing leases, which is included in loans, but did not have a material impact. The Company has elected certain practical expedients contained in this guidance, which, among other provisions, allowed the Company to not reassess the historical lease classification, initial direct costs, or existing contracts for the inclusion of leases. The Company has also elected the practical expedients for the use of hindsight in determining the lease term and the right-of-use assets, as well as an election not to apply the recognition requirements of the guidance to leases with terms of 12 months or less. The application of the hindsight practical expedient resulted in the determination that most renewal options would not be reasonably certain in determining the expected lease term. The Bank entered into a sale-leaseback transaction in 2016 that resulted in a deferred gain. Upon adoption of this guidance, the remaining deferred gain of $47.3 million after-tax was recognized immediately as a cumulative-effect adjustment to equity. For additional discussion of the sale-leaseback transaction, see Note 9, "Lease Obligations." The adoption of this guidance was applied retrospectively at the beginning of the period of adoption through a cumulative-effect adjustment and did not materially impact the Company's results of operations or liquidity but did result in a material increase in assets, liabilities, and equity. Premium Amortization on Purchased Callable Debt Securities: In March of 2017, the FASB issued ASU 2017-08 that shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. This guidance is effective for annual and interim periods beginning after December 15, 2018. The adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Improvements to Nonemployee Share-based Payment Accounting: In June of 2018, the FASB issued ASU 2018-07 that aligns the measurement and classification guidance for share-based payments to nonemployees with the guidance for share-based payments to employees. This guidance is effective for annual and interim periods beginning after December 15, 2018. The adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract: In August of 2018, the FASB issued ASU 2018-15 to reduce diversity in practice by clarifying when implementation costs are required to be capitalized in a cloud computing arrangement that is a service contract. This guidance is effective for annual and interim periods beginning after December 15, 2019. The early adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Derivatives and Hedging, Inclusion of the Secured Overnight Financing Rate ("SOFR") Overnight Index Swap Rate as a Benchmark Interest Rate for Hedge Accounting Purposes: In October of 2018, the FASB issued ASU 2018-16 adding the overnight index swap rate based on the SOFR to the list of United States benchmark interest rates eligible for hedge accounting purposes. This guidance is effective for annual and interim periods beginning after December 15, 2018. The adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Accounting Pronouncements Pending Adoption Measurement of Credit Losses on Financial Instruments: In June of 2016, the FASB issued ASU 2016-13 that will require entities to present financial assets measured at amortized cost at the net amount expected to be collected, considering an entity's current estimate of all expected credit losses. In addition, credit losses relating to available-for-sale debt securities will be required to be recorded through an allowance for credit losses, with changes in credit loss estimates recognized through current earnings. This guidance is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted, but not for periods beginning before December 15, 2018. The Company will adopt this guidance on January 1, 2020. Management is continuing its implementation efforts, which are led by a cross-functional working group. Management is in the process of determining the impact on the Company's financial condition, results of operations, liquidity, and regulatory capital ratios, but expects that the adoption of this guidance will result in an increase in the allowance for credit losses. The extent of the increase will depend on the composition of the loan portfolio, as well as the economic conditions and forecasts as of the adoption date. Management has completed its development of the forecasting model for all portfolio segments, which includes the establishment of economic factors, a one-year forecast period, and a one-year reversion to the historical average after the forecast period. Management will continue to evaluate and refine the overall process as well as its internal controls through the first quarter of 2020. Accounting for Goodwill Impairment: In January of 2017, the FASB issued ASU 2017-04 that simplifies the accounting for goodwill impairment for all entities. The new guidance eliminates the requirement to calculate the implied fair value of goodwill using the second step of the quantitative two-step goodwill impairment model prescribed under current accounting guidance. Under the new guidance, if a reporting unit's carrying amount exceeds its fair value, an entity will record an impairment charge based on that difference. This guidance is effective for annual and interim goodwill impairment testing dates beginning after December 15, 2019. Early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity. Changes to the Disclosure Requirements for Fair Value Measurement: In August of 2018, the FASB issued ASU 2018-13 that eliminates, modifies, and adds to certain fair value measurement disclosure requirements associated with the three-tiered fair value hierarchy. This guidance is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity. Changes to the Disclosure Requirements for Defined Benefit Plans: In August of 2018, the FASB issued ASU 2018-14 that makes minor changes and clarifications to the disclosure requirements for entities that sponsor defined benefit plans. This guidance is effective for annual and interim periods beginning after December 15, 2020. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity. Income Taxes: In December of 2019, the FASB issued ASU 2019-12 that removes certain exceptions to the general principles of accounting for income taxes. This guidance is effective for fiscal year, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Pending Park Bank On August 27, 2019, the Company entered into a merger agreement to acquire Bankmanagers Corp. ("Bankmanagers"), the holding company for Park Bank, based in Milwaukee Wisconsin. As of September 30, 2019, Bankmanagers had approximately $1.0 billion of assets, $875 million of deposits, and $700 million of loans. The merger agreement provides for a fixed exchange ratio of 29.9675 shares of Company common stock, plus $623.02 of cash, for each share of Bankmanagers common stock, subject to certain adjustments. As of the date of announcement, the overall transaction was valued at approximately $195 million. The transaction is subject to customary regulatory approvals and the completion of various closing conditions. Completed Acquisitions Bridgeview Bancorp, Inc. On May 9, 2019, the Company completed its acquisition of Bridgeview Bancorp, Inc. ("Bridgeview"), the holding company for Bridgeview Bank Group. At closing, the Company acquired $1.2 billion of assets, $1.0 billion of deposits, and $710.6 million of loans, net of fair value adjustments. Under the terms of the merger agreement, on May 9, 2019, each outstanding share of Bridgeview common stock was exchanged for 0.2767 shares of Company common stock, plus $1.66 of cash. In addition, each outstanding Bridgeview stock option was exchanged for the right to receive cash. This resulted in merger consideration of $135.4 million, which consisted of 4.7 million shares of Company common stock and $37.1 million of cash. Goodwill of $59.1 million associated with the acquisition was recorded by the Company. All Bridgeview operating systems were converted to the Company's operating platform during the second quarter of 2019. The fair value adjustments, including goodwill, associated with this transaction remain preliminary and may change as the Company continues to finalize the fair value of the assets and liabilities acquired. Northern Oak Wealth Management, Inc. On January 16, 2019, the Company completed its acquisition of Northern Oak Wealth Management, Inc., a registered investment adviser based in Milwaukee, Wisconsin with approximately $800 million of assets under management at closing. The fair value adjustments, including goodwill, associated with this transaction remain preliminary and may change as the Company continues to finalize the fair value of the assets and liabilities acquired. Northern States Financial Corporation On October 12, 2018, the Company completed its acquisition of Northern States Financial Corporation, ("Northern States"), the holding company for NorStates Bank, based in Waukegan, Illinois. At closing, the Company acquired $579.3 million of assets, $463.2 million of deposits, and $284.9 million of loans. Under the terms of the merger agreement, on October 12, 2018, each outstanding share of Northern States common stock was exchanged for 0.0363 shares of Company common stock. This resulted in merger consideration of $83.3 million, which consisted of 3.3 million shares of Company common stock. Goodwill of $30.0 million associated with the acquisition was recorded by the Company. All Northern States operating systems were converted to the Company's operating platform during the fourth quarter of 2018. During the third quarter of 2019, the Company finalized the fair value adjustments associated with the Northern States transaction, which required a measurement period adjustment to goodwill. This adjustment was recognized in the current period in accordance with accounting guidance applicable to business combinations. The following table presents the assets acquired and liabilities assumed, net of the fair value adjustments, in the Bridgeview and Northern States transactions as of the acquisition date. The assets acquired and liabilities assumed, both intangible and tangible, were recorded at their estimated fair values as of the acquisition date and have been accounted for under the acquisition method of accounting. Acquisition Activity (Dollar amounts in thousands, except share and per share data) Bridgeview Northern States May 9, 2019 October 12, 2018 Assets Cash and due from banks and interest-bearing deposits in other banks $ 35,097 160,145 Equity securities 6,966 3,915 Securities available-for-sale 263,090 47,149 Securities held-to-maturity 13,426 — FHLB and FRB stock 1,481 554 Loans 710,647 284,940 OREO 6,003 2,549 Investment in BOLI — 11,104 Goodwill 59,142 30,016 Other intangible assets 15,603 12,230 Premises, furniture, and equipment 17,681 5,820 Accrued interest receivable and other assets 35,997 20,911 Total assets $ 1,165,133 $ 579,333 Liabilities Noninterest-bearing deposits $ 179,267 $ 346,714 Interest-bearing deposits 807,487 116,446 Total deposits 986,754 463,160 Borrowed funds 1,746 18,218 Senior and subordinated debt 29,360 8,038 Accrued interest payable and other liabilities 11,921 6,614 Total liabilities 1,029,781 496,030 Consideration Paid Common stock (2019 - 4,728,541, shares issued at $28.61 per share, 2018 - 3,310,912 share issued at $25.16 per share), net of issuance costs 98,212 83,303 Cash paid 37,140 — Total consideration paid 135,352 83,303 $ 1,165,133 $ 579,333

Securities

Securities	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Securities	SECURITIES A summary of the Company's securities portfolio by category and maturity is presented in the following tables. Securities Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 33,939 $ 137 $ (1) $ 34,075 $ 37,925 $ 17 $ (175) $ 37,767 U.S. agency securities 249,502 758 (1,836) 248,424 144,125 45 (1,607) 142,563 Collateralized mortgage 1,547,805 14,893 (5,027) 1,557,671 1,336,531 3,362 (24,684) 1,315,209 Other mortgage-backed 678,804 7,728 (1,848) 684,684 477,665 520 (11,251) 466,934 Municipal securities 228,632 5,898 (99) 234,431 229,600 461 (2,874) 227,187 Corporate debt securities 112,797 1,791 (487) 114,101 86,074 — (3,725) 82,349 Total securities available-for-sale $ 2,851,479 $ 31,205 $ (9,298) $ 2,873,386 $ 2,311,920 $ 4,405 $ (44,316) $ 2,272,009 Securities Held-to-Maturity Municipal securities $ 21,997 $ — $ (763) $ 21,234 $ 10,176 $ — $ (305) $ 9,871 Equity Securities $ 42,136 $ 30,806 Remaining Contractual Maturity of Securities (Dollar amounts in thousands) As of December 31, 2019 Available-for-Sale Held-to-Maturity Amortized Cost Fair Value Amortized Cost Fair Value One year or less $ 131,855 $ 133,155 $ 8,672 $ 8,371 After one year to five years 193,902 195,814 6,037 5,828 After five years to ten years 299,113 302,062 4,417 4,264 After ten years — — 2,871 2,771 Securities that do not have a single contractual maturity date 2,226,609 2,242,355 — — Total $ 2,851,479 $ 2,873,386 $ 21,997 $ 21,234 The carrying value of securities available-for-sale that were pledged to secure deposits or for other purposes as permitted or required by law totaled $1.3 billion for December 31, 2019 and $1.2 billion for December 31, 2018. No securities held-to-maturity were pledged as of December 31, 2019 or 2018. Excluding securities issued or backed by the U.S. government and its agencies and U.S. government-sponsored enterprises, there were no investments in securities from one issuer that exceeded 10% of total stockholders' equity as of December 31, 2019 or 2018. There were no net securities gains (losses) recognized during the years ended December 31, 2019 and 2018. Certain securities acquired in the Bridgeview and Northern States transactions were sold shortly after the acquisition date, resulting in no gains or losses as they were recorded at fair value upon acquisition. Net realized losses on sales of securities of $1.9 million for 2017 consisted primarily of sales of CMOs and trust-preferred collateralized debt obligations at net losses of $3.2 million, which were partially offset by sales of municipal and other securities at net gains of $1.3 million. Accounting guidance requires that the credit portion of an OTTI charge be recognized through income. If a decline in fair value below carrying value is not attributable to credit deterioration and the Company does not intend to sell the security or believe it would not be more likely than not required to sell the security prior to recovery, the Company records the non-credit related portion of the decline in fair value in other comprehensive income (loss). The following table presents a rollforward of life-to-date OTTI recognized in earnings related to all securities available-for-sale held by the Company for the years ended December 31, 2019, 2018, and 2017. Changes in OTTI Recognized in Earnings (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ — $ — $ 23,345 OTTI included in earnings (1) : Reduction for securities sales (2) — — (23,345) Ending balance $ — $ — $ — (1) Included in net securities losses in the Consolidated Statements of Income. (2) These reductions were driven by the sale of 11 collateralized debt obligations ("CDOs") with a carrying value of $47.7 million during the year ended December 31, 2017. The following table presents the aggregate amount of unrealized losses and the aggregate related fair values of securities with unrealized losses as of December 31, 2019 and 2018. Securities in an Unrealized Loss Position (Dollar amounts in thousands) Less Than 12 Months Greater Than 12 Months Total Number of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses As of December 31, 2019 Securities Available-for-Sale U.S. treasury securities 5 $ 4,966 $ 1 $ — $ — $ 4,966 $ 1 U.S. agency securities 52 97,729 1,200 49,387 636 147,116 1,836 CMOs 148 187,470 2,177 412,083 2,850 599,553 5,027 MBSs 59 66,340 996 121,861 852 188,201 1,848 Municipal securities 16 9,384 89 3,104 10 12,488 99 Corporate debt securities 6 9,719 281 21,955 206 31,674 487 Total 286 $ 375,608 $ 4,744 $ 608,390 $ 4,554 $ 983,998 $ 9,298 Securities Held-to-Maturity Municipal securities 30 $ 12,202 $ 439 $ 9,032 $ 324 $ 21,234 $ 763 As of December 31, 2018 Securities Available-for-Sale U.S. treasury securities 17 $ 15,894 $ 57 $ 13,886 $ 118 $ 29,780 $ 175 U.S. agency securities 74 34,263 320 93,227 1,287 127,490 1,607 CMOs 234 171,901 1,671 863,747 23,013 1,035,648 24,684 MBSs 118 135,791 1,715 284,273 9,536 420,064 11,251 Municipal securities 423 60,863 558 109,935 2,316 170,798 2,874 Corporate debt securities 16 82,349 3,725 — — 82,349 3,725 Total 882 $ 501,061 $ 8,046 $ 1,365,068 $ 36,270 $ 1,866,129 $ 44,316 Securities Held-to-Maturity Municipal securities 5 $ — $ — $ 9,871 $ 305 $ 9,871 $ 305 Substantially all of the Company's CMOs and other MBSs are either backed by U.S. government-owned agencies or issued by U.S. government-sponsored enterprises. Municipal securities are issued by municipal authorities, and the majority are supported by third-party insurance or some other form of credit enhancement. Management does not believe any of these securities with

Loans

Loans	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Loans	LOANS Loans Held-for-Investment The following table presents the Company's loans held-for-investment by class. Loan Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Commercial and industrial $ 4,481,525 $ 4,120,293 Agricultural 405,616 430,928 Commercial real estate: Office, retail, and industrial 1,848,718 1,820,917 Multi-family 856,553 764,185 Construction 593,093 649,337 Other commercial real estate 1,383,708 1,361,810 Total commercial real estate 4,682,072 4,596,249 Total corporate loans 9,569,213 9,147,470 Home equity 851,454 851,607 1-4 family mortgages 1,927,078 1,017,181 Installment 492,585 430,525 Total consumer loans 3,271,117 2,299,313 Total loans $ 12,840,330 $ 11,446,783 Deferred loan fees included in total loans $ 7,972 $ 6,715 Overdrawn demand deposits included in total loans 10,675 8,583 The Company primarily lends to community-based and mid-sized businesses, commercial real estate customers, and consumers in its markets. Within these areas, the Company diversifies its loan portfolio by loan type, industry, and borrower. Commercial and industrial loans are underwritten after evaluating and understanding the borrower's ability to operate its business. As part of the underwriting process, the Company examines current and expected future cash flows to determine the ability of the borrower to repay its obligation. Commercial and industrial loans are primarily made based on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower and may incorporate a personal guarantee. The cash flows of the borrower may not be as expected, and the collateral securing these loans may fluctuate in value due to the success of the business or economic conditions. Most commercial and industrial loans are secured by the assets being financed or other business assets, such as accounts receivable or inventory. For loans secured by accounts receivable, the availability of funds for repayment substantially depends on the ability of the borrower to collect amounts due from its customers. Some short-term loans may be made on an unsecured basis. Agricultural loans are generally provided to meet seasonal production, equipment, and farm real estate borrowing needs of individual and corporate crop and livestock producers. Seasonal crop production loans are repaid by the liquidation of the financed crop that is typically covered by crop insurance. Equipment and real estate term loans are repaid through cash flows of the farming operation. As part of the underwriting process, the Company examines projected future cash flows, financial statement stability, and the value of the underlying collateral. Commercial real estate loans are subject to underwriting standards and processes similar to commercial and industrial loans. The repayment of commercial real estate loans depends on the successful operation of the property securing the loan or the business conducted on the property securing the loan. This category of loans may be more adversely affected by conditions in real estate markets. Management monitors and evaluates commercial real estate loans based on cash flow, collateral, geography, and risk rating criteria. The mix of properties securing the loans in our commercial real estate portfolio is balanced between owner-occupied and investor categories and is diverse in terms of type and geographic location, generally within the Company's markets. Construction loans are generally made based on estimates of costs and values associated with the completed projects and are underwritten utilizing feasibility studies, independent appraisal reviews, sensitivity analyses of absorption and lease rates, and financial analyses of the developers and property owners. Sources of repayment may be permanent long-term financing, sales of developed property, or an interim loan commitment until permanent financing is obtained. Generally, construction loans have a higher risk profile than other real estate loans since repayment is impacted by real estate values, interest rate changes, governmental regulation of real property, demand and supply of alternative real estate, the availability of long-term financing, and changes in general economic conditions. Consumer loans are centrally underwritten using a credit scoring model developed by the Fair Isaac Corporation ("FICO"), which employs a risk-based system to determine the probability that a borrower may default. Underwriting standards for home equity loans are heavily influenced by statutory requirements, which include loan-to-value and affordability ratios, risk-based pricing strategies, and documentation requirements. The home equity category consists mainly of revolving lines of credit secured by junior liens on owner-occupied real estate. Loan-to-value ratios on home equity loans and 1-4 family mortgages are based on the current appraised value of the collateral. Repayment for these loans is dependent on the borrower's continued financial stability, and is more likely to be impacted by adverse personal circumstances. The Bank is a member of the FHLB and FRB and has access to financing secured by designated assets that may include qualifying commercial real estate, residential and multi-family mortgages, home equity loans, and certain municipal and mortgage-backed securities. The carrying values of loans that were pledged to secure liabilities as of December 31, 2019 and 2018 are presented below. Carrying Value of Loans Pledged (Dollar amounts in thousands) As of December 31 2019 2018 Loans pledged to secure: FHLB advances (blanket pledge) $ 5,371,872 $ 4,443,268 FRB's Discount Window Primary Credit Program 1,173,250 1,166,128 Total $ 6,545,122 $ 5,609,396 As of December 31, 2019 and 2018, based on loans pledged under a blanket pledge agreement noted in the table above, the Bank was eligible to borrow up to $3.3 billion and $2.5 billion, respectively, in FHLB advances. As of December 31, 2019 and 2018, the Bank was eligible to borrow up to $874.3 million and $881.1 million, respectively, through the FRB's Discount Window Primary Credit Program based on assets pledged. For additional disclosure related to the Company's outstanding balance of borrowings, see Note 12, "Borrowed Funds." Loan Sales The following table presents loan sales for the years ended December 31, 2019, 2018, and 2017. Loan Sales (Dollar amounts in thousands) As of December 31, 2019 2018 2017 Corporate loan sales Proceeds from sales $ 14,650 $ 17,900 $ 52,974 Less book value of loans sold 14,149 17,498 51,781 Net gains on corporate sales (1) 501 402 1,193 1-4 family mortgage loan sales Proceeds from sales 474,384 245,967 258,626 Less book value of loans sold 464,893 240,807 252,741 Net gains on 1-4 family mortgage sales (2) 9,491 5,160 5,885 Total net gains on loan sales $ 9,992 $ 5,562 $ 7,078 (1) Net gains on corporate loan sales are included in other service charges, commissions, and fees in the Consolidated Statements of Income. (2) Net gains on 1-4 family mortgage loan sales are included in mortgage banking income in the Consolidated Statements of Income.

Acquired and Covered Loans

Acquired and Covered Loans	12 Months Ended
	Dec. 31, 2019
Transfers and Servicing [Abstract]
Acquired and Covered Loans	ACQUIRED AND COVERED LOANS Covered loans consist of loans acquired by the Company in FDIC-assisted transactions, which are covered by the FDIC Agreements. Acquired loans consist of all other loans that were acquired in business combinations that are not covered by the FDIC Agreements. Both acquired and covered loans are included in loans in the Consolidated Statements of Financial Condition. The significant accounting policies related to acquired and covered loans, which are classified as PCI and non-PCI, and the related FDIC indemnification asset, are presented in Note 1, "Summary of Significant Accounting Policies." Non-residential mortgage loans related to FDIC-assisted transactions are no longer covered under the FDIC Agreements. These non-residential loans, which totaled $7.8 million and $10.4 million as of December 31, 2019 and 2018, respectively, are included in acquired loans and no longer classified as covered loans. The losses on residential mortgage loans will continue to be covered under the FDIC Agreements through various dates between December 31, 2019 and September 30, 2020. The following table presents acquired and covered PCI and Non-PCI loans as of December 31, 2019 and 2018. Acquired and Covered Loans (Dollar amounts in thousands) As of December 31, 2019 2018 PCI Non-PCI Total PCI Non-PCI Total Acquired loans $ 161,794 $ 1,212,420 $ 1,374,214 $ 108,049 $ 1,247,492 $ 1,355,541 Covered loans 5,389 3,713 9,102 5,819 4,869 10,688 Total acquired and covered loans $ 167,183 $ 1,216,133 $ 1,383,316 $ 113,868 $ 1,252,361 $ 1,366,229 The outstanding balance of PCI loans was $243.0 million and $175.2 million as of December 31, 2019 and 2018, respectively. Acquired non-PCI loans that are renewed are no longer classified as acquired loans. These loans totaled $523.5 million and $458.0 million as of December 31, 2019 and 2018, respectively. In connection with the FDIC Agreements, the Company recorded an indemnification asset. The carrying value of the FDIC indemnification asset was $892,000, $2.1 million, and $3.3 million as of December 31, 2019, 2018, and 2017, respectively. Changes in the accretable yield for acquired and covered PCI loans were as follows. Changes in Accretable Yield (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 43,725 $ 32,957 $ 19,386 Additions 16,037 3,699 27,316 Accretion (20,607) (12,354) (15,529) Other (1) (146) 19,423 1,784 Ending balance $ 39,009 $ 43,725 $ 32,957 (1) Decreases result from the resolution of certain loans occurring earlier than anticipated while increases represent a rise in the expected future cash flows to be collected over the remaining estimated life of the underlying portfolio. Total accretion on acquired and covered PCI and non-PCI loans for December 31, 2019, 2018, and 2017 was $35.6 million, $19.5 million, and $33.9 million, respectively.

Past Due Loans, Allowance For C

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs	12 Months Ended
	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs	PAST DUE LOANS, ALLOWANCE FOR CREDIT LOSSES, IMPAIRED LOANS, AND TDRS Past Due and Non-accrual Loans The following table presents an aging analysis of the Company's past due loans as of December 31, 2019 and 2018. The aging is determined without regard to accrual status. The table also presents non-performing loans, consisting of non-accrual loans (the majority of which are past due) and loans 90 days or more past due and still accruing interest, as of each balance sheet date. Aging Analysis of Past Due Loans and Non-Performing Loans by Class (Dollar amounts in thousands) Aging Analysis (Accruing and Non-accrual) Non-performing Loans Current (1) 30-89 Days Past Due 90 Days or More Past Due Total Past Due Total Loans Non-accrual 90 Days or More Past Due, Still Accruing Interest As of December 31, 2019 Commercial and industrial $ 4,455,381 $ 11,468 $ 14,676 $ 26,144 $ 4,481,525 $ 29,995 $ 2,207 Agricultural 398,676 850 6,090 6,940 405,616 5,954 358 Commercial real estate: Office, retail, and industrial 1,830,321 2,943 15,454 18,397 1,848,718 25,857 546 Multi-family 853,762 211 2,580 2,791 856,553 2,697 — Construction 588,065 4,876 152 5,028 593,093 152 — Other commercial real estate 1,377,678 3,233 2,797 6,030 1,383,708 4,729 529 Total commercial real estate 4,649,826 11,263 20,983 32,246 4,682,072 33,435 1,075 Total corporate loans 9,503,883 23,581 41,749 65,330 9,569,213 69,384 3,640 Home equity 841,908 4,992 4,554 9,546 851,454 8,443 146 1-4 family mortgages 1,917,648 5,452 3,978 9,430 1,927,078 4,442 1,203 Installment 491,406 1,167 12 1,179 492,585 — 12 Total consumer loans 3,250,962 11,611 8,544 20,155 3,271,117 12,885 1,361 Total loans $ 12,754,845 $ 35,192 $ 50,293 $ 85,485 $ 12,840,330 $ 82,269 $ 5,001 As of December 31, 2018 Commercial and industrial $ 4,085,164 $ 8,832 $ 26,297 $ 35,129 $ 4,120,293 $ 33,507 $ 422 Agricultural 428,357 940 1,631 2,571 430,928 1,564 101 Commercial real estate: Office, retail, and industrial 1,803,059 8,209 9,649 17,858 1,820,917 6,510 4,081 Multi-family 759,402 1,487 3,296 4,783 764,185 3,107 189 Construction 645,774 3,419 144 3,563 649,337 144 — Other commercial real estate 1,353,442 4,921 3,447 8,368 1,361,810 2,854 2,197 Total commercial real estate 4,561,677 18,036 16,536 34,572 4,596,249 12,615 6,467 Total corporate loans 9,075,198 27,808 44,464 72,272 9,147,470 47,686 6,990 Home equity 843,217 6,285 2,105 8,390 851,607 5,393 104 1-4 family mortgages 1,009,925 4,361 2,895 7,256 1,017,181 3,856 1,147 Installment 428,836 1,648 41 1,689 430,525 — 41 Total consumer loans 2,281,978 12,294 5,041 17,335 2,299,313 9,249 1,292 Total loans $ 11,357,176 $ 40,102 $ 49,505 $ 89,607 $ 11,446,783 $ 56,935 $ 8,282 (1) PCI loans with an accretable yield are considered current. Allowance for Credit Losses The Company maintains an allowance for credit losses at a level deemed adequate by management to absorb estimated losses inherent in the existing loan portfolio. See Note 1, "Summary of Significant Accounting Policies," for the accounting policy for the allowance for credit losses. A rollforward of the allowance for credit losses by portfolio segment for the years ended December 31, 2019, 2018, and 2017 is presented in the table below. Allowance for Credit Losses by Portfolio Segment (Dollar amounts in thousands) Commercial, Industrial, and Agricultural Office, Retail, and Industrial Multi-family Construction Other Commercial Real Estate Consumer Reserve for Unfunded Commitments Total Allowance for Credit Losses Year Ended December 31, 2019 Beginning balance $ 63,276 $ 7,900 $ 2,464 $ 2,173 $ 4,934 $ 21,472 $ 1,200 $ 103,419 Charge-offs (28,008) (2,800) (340) (10) (800) (14,250) — (46,208) Recoveries 4,815 253 478 19 357 2,062 — 7,984 Net charge-offs (23,193) (2,547) 138 9 (443) (12,188) — (38,224) Provision for loan 22,747 2,227 348 (485) 1,917 17,273 — 44,027 Ending Balance $ 62,830 $ 7,580 $ 2,950 $ 1,697 $ 6,408 $ 26,557 $ 1,200 $ 109,222 Year Ended December 31, 2018 Beginning balance $ 55,791 $ 10,996 $ 2,534 $ 3,481 $ 6,381 $ 16,546 $ 1,000 $ 96,729 Charge-offs (36,477) (2,286) (5) (1) (410) (8,806) — (47,985) Recoveries 2,946 334 3 125 1,532 1,681 — 6,621 Net charge-offs (33,531) (1,952) (2) 124 1,122 (7,125) — (41,364) Provision for loan losses and other 41,016 (1,144) (68) (1,432) (2,569) 12,051 200 48,054 Ending balance $ 63,276 $ 7,900 $ 2,464 $ 2,173 $ 4,934 $ 21,472 $ 1,200 $ 103,419 Year Ended December 31, 2017 Beginning balance $ 40,709 $ 17,595 $ 3,261 $ 3,444 $ 7,739 $ 13,335 $ 1,000 $ 87,083 Charge-offs (22,885) (190) — (38) (755) (6,955) — (30,823) Recoveries 4,150 2,935 39 270 244 1,541 — 9,179 Net charge-offs (18,735) 2,745 39 232 (511) (5,414) — (21,644) Provision for loan 33,817 (9,344) (766) (195) (847) 8,625 — 31,290 Ending balance $ 55,791 $ 10,996 $ 2,534 $ 3,481 $ 6,381 $ 16,546 $ 1,000 $ 96,729 The table below provides a breakdown of loans and the related allowance for credit losses by portfolio segment as of December 31, 2019 and 2018. Loans and Related Allowance for Credit Losses by Portfolio Segment (Dollar amounts in thousands) Loans Allowance for Credit Losses Individually Evaluated for Impairment Collectively Evaluated for Impairment PCI Total Individually Evaluated for Impairment Collectively Evaluated for Impairment PCI Total As of December 31, 2019 Commercial, industrial, and $ 34,142 $ 4,807,114 $ 45,885 $ 4,887,141 $ 3,414 $ 59,108 $ 308 $ 62,830 Commercial real estate: Office, retail, and industrial 24,820 1,795,557 28,341 1,848,718 578 6,899 103 7,580 Multi-family 1,995 851,857 2,701 856,553 — 2,854 96 2,950 Construction 123 581,747 11,223 593,093 — 1,681 16 1,697 Other commercial real estate 3,241 1,323,635 56,832 1,383,708 — 4,867 1,541 6,408 Total commercial real estate 30,179 4,552,796 99,097 4,682,072 578 16,301 1,756 18,635 Total corporate loans 64,321 9,359,910 144,982 9,569,213 3,992 75,409 2,064 81,465 Consumer — 3,248,916 22,201 3,271,117 — 25,424 1,133 26,557 Reserve for unfunded — — — — — 1,200 — 1,200 Total loans $ 64,321 $ 12,608,826 $ 167,183 $ 12,840,330 $ 3,992 $ 102,033 $ 3,197 $ 109,222 As of December 31, 2018 Commercial, industrial, and $ 32,415 $ 4,514,349 $ 4,457 $ 4,551,221 $ 3,961 $ 58,947 $ 368 $ 63,276 Commercial real estate: Office, retail, and industrial 5,057 1,799,304 16,556 1,820,917 748 5,984 1,168 7,900 Multi-family 3,492 747,030 13,663 764,185 — 2,154 310 2,464 Construction — 644,499 4,838 649,337 — 2,019 154 2,173 Other commercial real estate 1,545 1,305,444 54,821 1,361,810 — 4,180 754 4,934 Total commercial real estate 10,094 4,496,277 89,878 4,596,249 748 14,337 2,386 17,471 Total corporate loans 42,509 9,010,626 94,335 9,147,470 4,709 73,284 2,754 80,747 Consumer — 2,279,780 19,533 2,299,313 — 20,094 1,378 21,472 Reserve for unfunded — — — — — 1,200 — 1,200 Total loans $ 42,509 $ 11,290,406 $ 113,868 $ 11,446,783 $ 4,709 $ 94,578 $ 4,132 $ 103,419 Loans Individually Evaluated for Impairment The following table presents loans individually evaluated for impairment by class of loan as of December 31, 2019 and 2018. PCI loans are excluded from this disclosure. Impaired Loans Individually Evaluated by Class (Dollar amounts in thousands) As of December 31, 2019 2018 Recorded Investment In Recorded Investment In Loans with No Specific Reserve Loans with a Specific Reserve Unpaid Principal Balance Specific Reserve Loans with No Specific Reserve Loans with a Specific Reserve Unpaid Principal Balance Specific Reserve Commercial and industrial $ 12,885 $ 15,516 $ 52,559 $ 2,456 $ 7,550 $ 23,349 $ 49,102 $ 3,960 Agricultural 1,889 3,852 9,293 958 1,318 198 3,997 1 Commercial real estate: Office, retail, and industrial 14,111 10,709 37,007 578 1,861 3,196 6,141 748 Multi-family 1,995 — 1,995 — 3,492 — 3,492 — Construction 123 — 123 — — — — — Other commercial real estate 3,241 — 3,495 — 1,545 — 1,612 — Total commercial real estate 19,470 10,709 42,620 578 6,898 3,196 11,245 748 Total impaired loans $ 34,244 $ 30,077 $ 104,472 $ 3,992 $ 15,766 $ 26,743 $ 64,344 $ 4,709 The following table presents the average recorded investment and interest income recognized on impaired loans by class for the years ended December 31, 2019, 2018, and 2017. PCI loans are excluded from this disclosure. Average Recorded Investment and Interest Income Recognized on Impaired Loans by Class (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Average Recorded Investment Interest Income Recognized (1) Average Recorded Investment Interest Income Recognized (1) Average Interest Income Recognized (1) Commercial and industrial $ 26,700 $ 115 $ 33,732 $ 225 $ 33,956 $ 1,059 Agricultural 4,374 20 2,026 32 279 101 Commercial real estate: Office, retail, and industrial 17,453 73 8,105 892 13,106 325 Multi-family 3,164 112 2,404 66 441 28 Construction 74 3 — — 7 136 Other commercial real estate 2,662 90 2,179 406 1,615 41 Total commercial real estate 23,352 278 12,688 1,364 15,169 530 Total impaired loans $ 54,427 $ 413 $ 48,445 $ 1,621 $ 49,404 $ 1,690 (1) Recorded using the cash basis of accounting. Credit Quality Indicators Corporate loans and commitments are assessed for credit risk and assigned ratings based on various characteristics, such as the borrower's cash flow, leverage, and collateral. Ratings for commercial credits are reviewed periodically. The following tables present credit quality indicators by class for corporate and consumer loans as of December 31, 2019 and 2018. Corporate Credit Quality Indicators by Class (Dollar amounts in thousands) Pass Special Mention (1) Substandard (2) Non-accrual (3) Total As of December 31, 2019 Commercial and industrial $ 4,324,709 $ 47,665 $ 79,156 $ 29,995 $ 4,481,525 Agricultural 350,827 32,764 16,071 5,954 405,616 Commercial real estate: Office, retail, and industrial 1,747,287 42,230 33,344 25,857 1,848,718 Multi-family 839,615 8,279 5,962 2,697 856,553 Construction 564,495 17,977 10,469 152 593,093 Other commercial real estate 1,295,155 39,788 44,036 4,729 1,383,708 Total commercial real estate 4,446,552 108,274 93,811 33,435 4,682,072 Total corporate loans $ 9,122,088 $ 188,703 $ 189,038 $ 69,384 $ 9,569,213 As of December 31, 2018 Commercial and industrial $ 3,952,066 $ 74,878 $ 59,842 $ 33,507 $ 4,120,293 Agricultural 407,542 10,070 11,752 1,564 430,928 Commercial real estate: Office, retail, and industrial 1,735,426 35,853 43,128 6,510 1,820,917 Multi-family 745,131 9,273 6,674 3,107 764,185 Construction 624,446 16,370 8,377 144 649,337 Other commercial real estate 1,294,128 47,736 17,092 2,854 1,361,810 Total commercial real estate 4,399,131 109,232 75,271 12,615 4,596,249 Total corporate loans $ 8,758,739 $ 194,180 $ 146,865 $ 47,686 $ 9,147,470 (1) Loans categorized as special mention exhibit potential weaknesses that require the close attention of management since these potential weaknesses may result in the deterioration of repayment prospects in the future. (2) Loans categorized as substandard exhibit a well-defined weakness that may jeopardize the liquidation of the debt. These loans continue to accrue interest because they are well-secured and collection of principal and interest is expected within a reasonable time. (3) Loans categorized as non-accrual exhibit a well-defined weakness that may jeopardize the liquidation of the debt or result in a loss if the deficiencies are not corrected. Consumer Credit Quality Indicators by Class (Dollar amounts in thousands) Performing Non-accrual Total As of December 31, 2019 Home equity $ 843,011 $ 8,443 $ 851,454 1-4 family mortgages 1,922,636 4,442 1,927,078 Installment 492,585 — 492,585 Total consumer loans $ 3,258,232 $ 12,885 $ 3,271,117 As of December 31, 2018 Home equity $ 846,214 $ 5,393 $ 851,607 1-4 family mortgages 1,013,325 3,856 1,017,181 Installment 430,525 — 430,525 Total consumer loans $ 2,290,064 $ 9,249 $ 2,299,313 TDRs TDRs are generally performed at the request of the individual borrower and may include forgiveness of principal, reduction in interest rates, changes in payments, and maturity date extensions. The table below presents TDRs by class as of December 31, 2019 and 2018. See Note 1, "Summary of Significant Accounting Policies," for the accounting policy for TDRs. TDRs by Class (Dollar amounts in thousands) As of December 31, 2019 2018 Accruing Non-accrual (1) Total Accruing Non-accrual (1) Total Commercial and industrial $ 227 $ 16,420 $ 16,647 $ 246 $ 5,994 $ 6,240 Agricultural — — — — — — Commercial real estate: Office, retail, and industrial — 3,600 3,600 — — — Multi-family 163 — 163 557 — 557 Construction — — — — — — Other commercial real estate 170 — 170 181 — 181 Total commercial real estate 333 3,600 3,933 738 — 738 Total corporate loans 560 20,020 20,580 984 5,994 6,978 Home equity 36 240 276 113 327 440 1-4 family mortgages 637 — 637 769 291 1,060 Installment — 254 254 — — — Total consumer loans 673 494 1,167 882 618 1,500 Total loans $ 1,233 $ 20,514 $ 21,747 $ 1,866 $ 6,612 $ 8,478 (1) These TDRs are included in non-accrual loans in the preceding tables. TDRs are included in the calculation of the allowance for credit losses in the same manner as impaired loans. There were $2.2 million of specific reserves related to TDRs as of December 31, 2019 and no specific reserves related to TDRs as of December 31, 2018. There were no material restructurings during the year ended December 31, 2018. The following table presents a summary of loans that were restructured during the years ended December 31, 2019 and 2017. Loans Restructured During the Period (Dollar amounts in thousands) Number of Loans Pre-Modification Recorded Investment Funds Disbursed Interest and Escrow Capitalized Charge-offs Post-Modification Recorded Investment Year Ended December 31, 2019 Commercial and industrial 5 $ 13,616 $ — $ — $ 1,424 $ 12,192 Office, retail, and industrial 2 4,473 — — 873 3,600 Multi-family 1 12 — — — 12 Total loans restructured during the period 8 $ 18,101 $ — $ — $ 2,297 $ 15,804 Year Ended December 31, 2017 Commercial and industrial 12 $ 26,733 $ 9,035 $ — $ 6,232 $ 29,536 Office, retail, and industrial 2 3,656 — — — 3,656 Total loans restructured during the period 14 $ 30,389 $ 9,035 $ — $ 6,232 $ 33,192 Accruing TDRs that do not perform in accordance with their modified terms are transferred to non-accrual. No TDRs had payment defaults during the years ended December 31, 2019, 2018, and 2017 where the default occurred within twelve months of the restructure date. A rollforward of the carrying value of TDRs for the years ended December 31, 2019, 2018, and 2017 is presented in the following table. TDR Rollforward (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Accruing Beginning balance $ 1,866 $ 1,796 $ 2,291 Additions 12 — 15,819 Net payments (262) (50) (1,923) Returned to performing status — — — Net transfers (to) from non-accrual (383) 120 (14,391) Ending balance 1,233 1,866 1,796 Non-accrual Beginning balance 6,612 24,533 6,297 Additions 18,089 527 14,570 Net payments (1,013) (14,403) (4,380) Charge-offs (3,557) (3,925) (6,345) Transfers to OREO — — — Loans sold — — — Net transfers from (to) accruing 383 (120) 14,391 Ending balance 20,514 6,612 24,533 Total TDRs $ 21,747 $ 8,478 $ 26,329 There were $530,000 and $3.8 million of commitments to lend additional funds to borrowers with TDRs as of December 31, 2019 and 2018, respectively.

Premises, Furniture, and Equipm

Premises, Furniture, and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Premises, Furniture, and Equipment	PREMISES, FURNITURE, AND EQUIPMENT The following table summarizes the Company's premises, furniture, and equipment by category. Premises, Furniture, and Equipment (Dollar amounts in thousands) As of December 31, 2019 2018 Land $ 30,807 $ 28,187 Premises 132,427 122,003 Furniture and equipment 137,349 127,421 Total cost 300,583 277,611 Accumulated depreciation (159,411) (148,831) Net book value of premises, furniture, and equipment 141,172 128,780 Assets held-for-sale 6,824 3,722 Premises, furniture, and equipment, net $ 147,996 $ 132,502 As of December 31, 2019 and 2018, assets held-for-sale consisted of former branches that are no longer in operation and parcels of land previously purchased for expansion.

Lease Obligations

Lease Obligations	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease Obligations	LEASE OBLIGATIONS The Company has the right to utilize certain premises under non-cancelable operating leases with varying maturity dates through the year ending December 31, 2059. As of December 31, 2019, the weighted-average remaining lease term on these leases was 11.19 years. Various leases contain renewal or termination options controlled by the Company or options to purchase the leased property during or at the expiration of the lease period at specific prices. Some leases contain escalation clauses calling for rentals to be adjusted for increased real estate taxes and other operating expenses or proportionately adjusted for increases in consumer or other price indices. Variable payments for real estate taxes and other operating expenses are considered to be non-lease components and are excluded from the determination of the lease liability. In addition, the Company rents or subleases certain real estate to third-parties. The following summary reflects the future minimum payments by year required under operating leases that have initial or remaining non-cancelable lease terms in excess of one year and a reconciliation of those payments to the Company's lease liability as of December 31, 2019. Lease Liability (Dollar amounts in thousands) Total Year Ending December 31, 2020 $ 17,855 2021 17,873 2022 18,007 2023 18,175 2024 18,090 2025 and thereafter 103,967 Total minimum lease payments 193,967 Discount (1) (32,403) Lease liability (2) $ 161,564 (1) Represents the net present value adjustment related to minimum lease payments. (2) Included in accrued interest payable and other liabilities in the Consolidated Statements of Financial Condition. The discount rate for the Company's operating leases is the rate implicit in the lease and, if that rate cannot be readily determined, the Company's incremental borrowing rate. The weighted-average discount rate on the Company's operating leases was 3.19% as of December 31, 2019. As of December 31, 2019, right-of-use assets of $141.0 million associated with lease liabilities were included in accrued interest receivable and other assets in the Consolidated Statements of Financial Condition. The following table presents net operating lease expense for the years ended December 31, 2019, 2018, and 2017. Net Operating Lease Expense (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Lease expense charged to operations $ 17,681 $ 24,880 $ 18,666 Accretion of operating lease intangible (1) (162) (972) (1,180) Accretion of deferred gain on sale-leaseback transaction (1) — (9,126) (5,872) Rental income from premises leased to others (1) (720) (510) (682) Net operating lease expense $ 16,799 $ 14,272 $ 10,932 (1) Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income. During 2016, the Bank completed a sale-leaseback transaction, whereby the Bank sold to a third-party 55 branches and concurrently entered into triple net lease agreements with certain affiliates of the third-party for each of the branches sold. The sale-leaseback transaction resulted in a pre-tax gain of $88.0 million, net of transaction related expenses, of which $5.5 million was immediately recognized in earnings. Remaining deferred pre-tax gains were $65.5 million as of December 31, 2018. Upon adoption of new lease guidance on January 1, 2019, the remaining after-tax gain of $47.3 million was recognized as a

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	GOODWILL AND OTHER INTANGIBLE ASSETS The Company's annual goodwill impairment test was performed as of October 1, 2019. It was determined that no impairment existed as of that date or as of December 31, 2019. For a discussion of the accounting policies for goodwill and other intangible assets, see Note 1, "Summary of Significant Accounting Policies." The following table presents changes in the carrying amount of goodwill for the years ended December 31, 2019, 2018, and 2017. Changes in the Carrying Amount of Goodwill (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 728,809 $ 697,608 $ 340,879 Acquisitions 67,947 31,201 356,729 Ending balance $ 796,756 $ 728,809 $ 697,608 The increase in goodwill for the year ended December 31, 2019 resulted from the Bridgeview and Northern Oak acquisitions and measurement period adjustment related to finalizing the fair values of the assets acquired and liabilities assumed in the Northern States acquisition. During the year ended December 31, 2018 the increase resulted from the Northern States acquisition and measurement period adjustment related to finalizing the fair values of the assets acquired and liabilities assumed in the Premier Asset Management LLC ("Premier") acquisition. During the year ended December 31, 2017, the increase resulted from the Standard Bancshares, Inc. and Premier acquisitions and measurement period adjustments related to the NI Bancshares Corporation acquisition. See Note 3, "Acquisitions," for additional detail regarding transactions completed in 2019 and 2018. The Company's other intangible assets consist of core deposit intangibles and trust department customer relationship intangibles, which are being amortized over their estimated useful lives. Other intangible assets are subject to impairment testing when events or circumstances indicate that their carrying amount may not be recoverable. The increase in other intangible assets for the year ended December 31, 2019 resulted from the Bridgeview and Northern Oak acquisitions. The increase in other intangible assets for the year ended December 31, 2018 resulted from the Northern States acquisition. During 2019 there were no events or circumstances to indicate impairment. Other Intangible Assets (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Gross Accumulated Amortization Net Gross Accumulated Amortization Net Gross Accumulated Amortization Net Beginning balance $ 110,206 $ 48,271 $ 61,935 $ 97,976 $ 40,827 $ 57,149 $ 58,959 $ 32,962 $ 25,997 Additions 27,052 — 27,052 12,230 — 12,230 39,017 — 39,017 Amortization expense — 10,481 (10,481) — 7,444 (7,444) — 7,865 (7,865) Ending balance $ 137,258 $ 58,752 $ 78,506 $ 110,206 $ 48,271 $ 61,935 $ 97,976 $ 40,827 $ 57,149 Weighted-average remaining life (in years) 7.5 7.8 8.3 Estimated remaining useful lives (in years) 0.5 to 9.3 0.7 to 9.8 0.2 to 9.3 Scheduled Amortization of Other Intangible Assets (Dollar amounts in thousands) Total Year Ending December 31, 2020 $ 10,951 2021 10,875 2022 10,796 2023 10,418 2024 10,172 2025 and thereafter 25,294 Total $ 78,506

Deposits

Deposits	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Deposits	DEPOSITS The following table presents the Company's deposits by type. Summary of Deposits (Dollar amounts in thousands) As of December 31, 2019 2018 Demand deposits $ 3,802,422 $ 3,642,989 Savings deposits 2,062,848 2,053,494 NOW accounts 2,259,505 2,063,213 Money market deposits 2,093,049 1,783,512 Time deposits less than $100,000 1,615,609 1,348,664 Time deposits greater than $100,000 1,417,845 1,192,240 Total deposits $ 13,251,278 $ 12,084,112 The following table provides maturity information related to the Company's time deposits. Scheduled Maturities of Time Deposits (Dollar amounts in thousands) Total Year Ending December 31, 2020 $ 2,800,474 2021 150,806 2022 34,140 2023 17,894 2024 29,792 2025 and thereafter 348 Total $ 3,033,454

Borrowed Funds

Borrowed Funds	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Borrowed Funds	BORROWED FUNDS The following table summarizes the Company's borrowed funds by funding source. Summary of Borrowed Funds (Dollar amounts in thousands) As of December 31, 2019 2018 Securities sold under agreements to repurchase $ 103,515 $ 121,079 Federal funds purchased 160,000 — FHLB advances 1,395,243 785,000 Total borrowed funds $ 1,658,758 $ 906,079 Securities sold under agreements to repurchase and federal funds purchased generally mature within 1 to 90 days from the transaction date. Securities sold under agreements to repurchase are treated as financings and the obligations to repurchase securities sold are included as a liability in the Consolidated Statements of Financial Condition. Repurchase agreements are secured by U.S. treasury and agency securities, which are held in third-party pledge accounts, if required. The securities underlying the agreements remain in the respective asset accounts. As of December 31, 2019, the Company did not have amounts at risk under repurchase agreements with any individual counterparty or group of counterparties that exceeded 10% of stockholders' equity. The Bank is a member of the FHLB and has access to term financing from the FHLB. These advances are secured by designated assets that may include qualifying commercial real estate, residential and multi-family mortgages, home equity loans, and certain municipal and mortgage-backed securities. See Note 5, "Loans," for detail of the carrying value of loans pledged. As of December 31, 2019, FHLB advances, including certain putable advances, had fixed interest rates that range from 0.70% to 2.04% and maturity dates that range from January 2020 to November 2029. The Company hedges interest rates on borrowed funds using interest rate swaps through which the Company receives variable amounts and pays fixed amounts. See Note 20, "Derivative Instruments and Hedging Activities" for a detailed discussion of interest rate swaps. The following table presents short-term credit lines available for use, for which the Company did not have an outstanding balance as of December 31, 2019 and 2018. Short-Term Credit Lines Available for Use (Dollar amounts in thousands) As of December 31, 2019 2018 FRB's Discount Window Primary Credit Program $ 874,256 $ 881,113 Available federal funds lines 718,000 684,000 Correspondent bank line of credit 50,000 50,000 On September 27, 2016, the Company entered into a loan agreement with U.S. Bank National Association providing for a $50.0 million short-term, unsecured revolving credit facility. On September 26, 2019, the Company entered into a third amendment to this credit facility, which extends the maturity to September 26, 2020. Advances will bear interest at a rate equal to one-month LIBOR plus 1.75%, adjusted on a monthly basis, and the Company must pay an unused facility fee equal to 0.35% per annum on a quarterly basis. Management may use this line of credit for general corporate purposes. As of December 31, 2019 and 2018, no amount was outstanding under the facility.

Senior and Subordinated Debt

Senior and Subordinated Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Senior and Subordinated Debt	SENIOR AND SUBORDINATED DEBT The following table presents the Company's senior and subordinated debt by issuance. Senior and Subordinated Debt (Dollar amounts in thousands) As of December 31, Issuance Date Maturity Date Interest Rate 2019 2018 Subordinated notes September 2016 September 2026 5.875% $ 147,637 $ 147,282 Junior subordinated debentures: First Midwest Capital Trust I ("FMCT") November 2003 December 2033 6.950% 37,805 37,803 Great Lakes Statutory Trust II ("GLST II") (1) December 2005 December 2035 L+1.400% (2) 4,674 4,580 Great Lakes Statutory Trust III ("GLST III") (1) June 2007 September 2037 L+1.700% (2) 6,187 6,071 Northern States Statutory Trust I ("NSST I") (1) September 2005 September 2035 L+1.800% (2) 8,206 8,072 Bridgeview Statutory Trust I ("BST") (1) July 2001 July 2031 L+3.580% (2) 14,542 — Bridgeview Capital Trust II ("BCT") (1) December 2002 January 2033 L+3.350% (2) 14,897 — Total junior subordinated debentures 86,311 56,526 Total senior and subordinated debt $ 233,948 $ 203,808 (1) The junior subordinated debentures related to BST, BCT, GLST II, GLST III, and NSST I were assumed by the Company through acquisitions. These amounts include acquisition adjustment discounts that total $7.2 million and $6.0 million as of December 31, 2019 and 2018, respectively. (2) The interest rates are variable rates based on three-month LIBOR plus the margin indicated. Junior Subordinated Debentures FMCT, GLST II, GLST III, NSST I, BST, and BCT are Delaware statutory business trusts. These trusts were established for the purpose of issuing trust-preferred securities and lending the proceeds to the Company in return for junior subordinated debentures of the Company. The junior subordinated debentures are the sole assets of each trust. Therefore, each trust's ability to pay amounts due on the trust-preferred securities is solely dependent on the Company making payments on the related junior subordinated debentures. The trust-preferred securities are subject to mandatory redemption, in whole or in part, on repayment of the junior subordinated debentures at the stated maturity date or on redemption. The Company guarantees payments of distributions and redemptions on the trust-preferred securities on a limited basis. For regulatory capital purposes, the Tier 1 capital treatment of trust-preferred securities ended during 2018 due to the Company's asset growth, and those securities now are instead treated as Tier 2 capital. The statutory trusts qualify as variable interest entities for which the Company is not the primary beneficiary. Consequently, the accounts of those entities are not consolidated in the Company's financial statements.

Material Transactions Affecting

Material Transactions Affecting Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Material Transactions Affecting Stockholders' Equity	MATERIAL TRANSACTIONS AFFECTING STOCKHOLDERS' EQUITY Issued Common Stock On May 9, 2019, the Company issued 4.7 million shares of its common stock with a market value of $28.61 per share at issuance as part of the consideration in the Bridgeview acquisition. Additional information regarding the Bridgeview acquisition is presented in Note 3, "Acquisitions." On October 12, 2018, the Company issued 3.3 million shares of its common stock with a market value of $25.16 per share at issuance as part of the consideration in the Northern States acquisition. Additional information regarding the Northern States acquisition is presented in Note 3, "Acquisitions." Stock Repurchases On March 19, 2019, the Company announced a new stock repurchase program that authorizes the Company to repurchase up to $180 million of its common stock from time to time on the open market or in privately negotiated transactions, at the discretion of the Company. The Company repurchased 1.7 million shares of its common stock at a total cost of $33.9 million during the year ended December 31, 2019. On February 19, 2020, the Board approved a new stock repurchase program, under which the Company is authorized to repurchase up to $200 million of its outstanding common stock through December 31, 2021. This new stock repurchase program replaces the prior $180 million program, which was scheduled to expire in March 2020. The stock repurchase program does not obligate the Company to repurchase a specific dollar amount or number of shares, and the program may be extended, modified, or discontinued at any time. Repurchases under the Company's repurchase programs are made at prices determined by the Company. Authorized Common Stock On May 17, 2017, the Company's stockholders approved and adopted an amendment to the Company's Restated Certificate of Incorporation. The amendment increased the Company's authorized common stock by 100,000,000 shares. Following this amendment, the Company is now authorized to issue a total of 251,000,000 shares, including 1,000,000 shares of preferred stock, without a par value, and 250,000,000 shares of common stock, $0.01 par value per share. Quarterly Dividend on Common Shares The Company's Board of Directors (the "Board") declared a quarterly cash dividend on the Company's common stock of $0.09 per share for the first quarter of 2017 with an increase in the quarterly cash dividend to $0.10 per share for each of the quarters thereafter in 2017. The Company increased the quarterly cash dividend to $0.11 per share for each of the first three quarters of 2018 with an increase to $0.12 per share for the fourth quarter of 2018 and first quarter of 2019. The quarterly cash dividend increased to $0.14 per share for each of the quarters from the second quarter of 2019 through the fourth quarter of 2019. Other than share-based compensation, which is disclosed in Note 18, "Share-Based Compensation", there were no additional material transactions that affected stockholders' equity during the three years ended December 31, 2019.

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Common Share	EARNINGS PER COMMON SHARE The table below displays the calculation of basic and diluted EPS. Basic and Diluted EPS (Amounts in thousands, except per share data) Years Ended December 31, 2019 2018 2017 Net income $ 199,738 $ 157,870 $ 98,387 Net income applicable to non-vested restricted shares (1,681) (1,312) (916) Net income applicable to common shares $ 198,057 $ 156,558 $ 97,471 Weighted-average common shares outstanding: Weighted-average common shares outstanding (basic) 108,156 102,850 101,423 Dilutive effect of common stock equivalents 428 4 20 Weighted-average diluted common shares outstanding 108,584 102,854 101,443 Basic EPS $ 1.83 $ 1.52 $ 0.96 Diluted EPS 1.82 1.52 0.96 Anti-dilutive shares not included in the computation of diluted EPS (1) — 27 229 (1) This amount represents outstanding stock options for which the exercise price is greater than the average market price of the Company's common stock. The final outstanding stock options were exercised during the first quarter of 2018.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Components of Income Tax Expense (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Current income tax expense (benefit): Federal $ 50,141 $ 13,497 $ 93,540 State 5,116 (619) 104 Total 55,257 12,878 93,644 Deferred income tax expense (benefit): Federal (1,879) 14,489 (12,219) State 12,823 11,820 8,142 Total 10,944 26,309 (4,077) Total income tax expense $ 66,201 $ 39,187 $ 89,567 Federal income tax expense and the related effective income tax rate are influenced by the amount of tax-exempt income derived from investment securities and BOLI in relation to pre-tax income as well as state income taxes. State income tax expense and the related effective income tax rate are driven by both the amount of state tax-exempt income in relation to pre-tax income and state tax rules for consolidated/combined reporting and sourcing of income and expense. Federal income tax reform was enacted on December 22, 2017. The new law enacted various changes to the federal corporate income tax, the most impactful being the reduction in the corporate tax rate to a flat 21%. Components of Effective Tax Rate (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Amount % of Pretax Income Amount % of Pretax Income Amount % of Pretax Income Statutory federal income tax $ 55,847 21.0 $ 41,382 21.0 $ 65,784 35.0 Increase (decrease) in income taxes resulting from: State income tax, net of federal income tax effect 14,172 5.3 8,846 4.5 5,069 2.7 Tax-exempt income, net of interest expense disallowance (3,234) (1.2) (3,104) (1.6) (5,065) (2.7) Deferred tax asset revaluation — — (8,721) (4.4) 23,709 12.6 Other (584) (0.2) 784 0.4 70 0.1 Total $ 66,201 24.9 % $ 39,187 19.9 % $ 89,567 47.7 % The increase in income tax expense and the effective tax rate for the year ended December 31, 2019 compared to 2018 was due primarily to the increase in taxable income and an increase in the state effective tax rate. The 2018 effective tax rate was favorably impacted by the decrease in the applicable federal income tax rate from 35% to 21% and the recognition of $8.7 million of income tax benefits resulting from federal income tax reform. As of December 31, 2017, the Company's revaluation of its deferred tax assets and liabilities at the newly enacted 21% rate resulted in additional tax expense of $26.6 million, partly offset by a $2.8 million benefit due to a change in the Illinois income tax rate. As of December 31, 2019, the Company's retained earnings included an appropriation for an acquired thrift's tax bad debt reserves of approximately $5.8 million, as well as $5.8 million and $2.5 million for December 31, 2018 and 2017, respectively, for which no provision for federal or state income taxes has been made. If, in the future, this portion of retained earnings were distributed as a result of the liquidation of the Company or its subsidiaries, federal and state income taxes would be imposed at the then applicable rates. Differences between the amounts reported in the consolidated financial statements and the tax basis of assets and liabilities result in temporary differences for which deferred tax assets and liabilities were recorded. Deferred Tax Assets and Liabilities (Dollar amounts in thousands) As of December 31, 2019 2018 Deferred tax assets: Lease liability 33,871 $ — Allowance for credit losses 21,010 19,591 Federal net operating loss ("NOL") carryforwards 19,505 8,871 Non-equity based compensation 7,115 2,210 Equity based compensation 5,043 3,971 OREO 1,996 1,460 Alternative minimum tax ("AMT") and other credit carryforwards 368 244 Deferred gain on sale-leaseback transaction — 13,752 State NOL carryforwards — 6,240 Deferred incentives — 1,382 Property valuation adjustments — 1,214 Other 6,988 5,232 Total deferred tax assets 95,896 64,167 Deferred tax liabilities: Right-of-use asset (29,611) — Accrued retirement benefits (8,453) (8,502) Fixed assets (5,648) (7,322) Deferred loan fees and costs (5,445) (4,985) Acquisition adjustments (1,261) (686) Other (2,821) (2,823) Total deferred tax liabilities (53,239) (24,318) Deferred tax valuation allowance — — Net deferred tax assets 42,657 39,849 Tax effect of adjustments related to other comprehensive income (loss) 725 20,280 Net deferred tax assets including adjustments $ 43,382 $ 60,129 NOL carryforwards available to offset future taxable income: Federal gross NOL carryforwards, begin to expire in 2030 $ 92,880 $ 42,242 Illinois gross NOL carryforwards — 209,802 Indiana gross NOL carryforwards — 14,260 Wisconsin gross NOL carryforwards — 1,212 AMT credits 204 — During the year ended December 31, 2019, the Company recorded net deferred tax assets of $32.1 million related to the Bridgeview acquisition. During the year ended December 31, 2018, the Company recorded net deferred tax assets of $17.0 million related to the Northern States acquisition. During the years ended December 31, 2019 and 2018, the Company transferred certain loans into real estate mortgage investment conduit trusts, which are classified as loans in the financial statements and as securities for tax purposes. Net deferred tax assets are included in other assets in the accompanying Consolidated Statements of Financial Condition. Management believes that it is more likely than not that net deferred tax assets will be fully realized and no valuation allowance is required. Uncertainty in Income Taxes The Company files a U.S. federal income tax return and state income tax returns in various states. Income tax returns filed by the Company are no longer subject to examination by federal and state income tax authorities for years prior to 2016, except for amended changes to 2015 federal and Illinois tax returns and 2014 Iowa and Wisconsin tax returns. Rollforward of Unrecognized Tax Benefits (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 16,350 $ 16,248 $ 2,039 Additions for tax positions relating to the current year 1,158 1,209 845 Additions for tax positions relating to prior years — 582 13,389 Reductions for tax positions relating to prior years (224) (60) (25) Reductions for settlements with taxing authorities (900) (1,629) — Ending balance $ 16,384 $ 16,350 $ 16,248 Interest and penalties not included above (1) : Interest expense (income) , net of tax effect, and penalties $ 38 $ (21) $ 118 Accrued interest and penalties, net of tax effect, at end of year 208 170 191 (1) Included in income tax expense in the Consolidated Statements of Income. The Company does not anticipate that the amount of uncertain tax positions will significantly increase or decrease in the next twelve months. Included in the balance as of December 31, 2019, 2018, and 2017 are tax positions totaling $13.0 million, $13.1 million and $12.9 million, respectively, which would favorably affect the Company's effective tax rate if recognized in future periods.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Profit Sharing Plan The Company has a defined contribution retirement savings plan (the "Profit Sharing Plan") that covers qualified employees who meet certain eligibility requirements. The Profit Sharing Plan gives qualified employees (including certain highly compensated employees) the option to contribute up to 100% of their pre-tax base salary through salary deductions under Section 401(k) of the Internal Revenue Code. At the employees' direction, employee contributions are invested among a variety of investment alternatives. In addition, the Company makes a matching contribution of 4% of the eligible employee's compensation. On an annual basis, the Company automatically contributes 2% of the employee's eligible compensation regardless of voluntary contributions made by the employee. There is also a discretionary profit sharing component of the Profit Sharing Plan, which permits the Company to distribute up to 15% of the employee's compensation. The Company's matching contributions vest immediately, while the automatic and discretionary components vest over six Profit Sharing Plan (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Profit sharing expense (1) $ 8,226 $ 7,803 $ 7,346 Company dividends received by the Profit Sharing Plan $ 414 $ 457 $ 441 Company shares held by the Profit Sharing Plan at the end of the year: Number of shares 812,886 1,047,213 1,079,975 Fair value $ 18,745 $ 20,745 $ 25,930 (1) Included in retirement and other employee benefits in the Consolidated Statements of Income. Pension Plan The Company sponsors a defined benefit pension plan (the "Pension Plan"), which provides for retirement benefits based on years of service and compensation levels of the participants. The Pension Plan covers employees who met certain eligibility requirements and were hired before April 1, 2007, the date it was amended to eliminate new enrollment of new participants. Effective January 1, 2014, benefit accruals were frozen under the Pension Plan. Actuarially determined pension costs are charged to current operations and included in retirement and other employee benefits in the Consolidated Statements of Income. The Company's funding policy is to contribute amounts to the Pension Plan that are sufficient to meet the minimum funding requirements of the Employee Retirement Income Security Act of 1974 plus additional amounts as the Company deems appropriate. Pension Plan Cost and Obligations (Dollar amounts in thousands) As of December 31, 2019 2018 Accumulated benefit obligation $ 70,236 $ 58,271 Change in projected benefit obligation Beginning balance $ 58,271 $ 67,923 Service cost — — Interest cost 1,841 2,031 Settlements (4,268) (7,199) Actuarial loss (gain) 15,200 (3,717) Benefits paid (808) (767) Ending balance $ 70,236 $ 58,271 Change in fair value of plan assets Beginning balance $ 76,210 $ 66,159 Actual return on plan assets 21,156 (6,983) Benefits paid (808) (767) Employer contributions — 25,000 Settlements (4,268) (7,199) Ending balance $ 92,290 $ 76,210 Funded status recognized in the Consolidated Statements of Financial Condition Noncurrent asset $ 22,054 $ 17,939 Amounts recognized in accumulated other comprehensive loss Prior service cost $ — $ — Net loss 25,721 29,345 Net amount recognized $ 25,721 $ 29,345 Actuarial losses included in accumulated other comprehensive loss as a percent of Accumulated benefit obligation 36.6 % 50.4 % Fair value of plan assets 27.9 % 38.5 % Amounts expected to be amortized from accumulated other comprehensive loss into net periodic benefit cost in the next fiscal year Prior service cost $ — $ — Net loss 820 426 Net amount expected to be recognized $ 820 $ 426 Weighted-average assumptions at the end of the year used to determine the actuarial present value of the projected benefit obligation Discount rate 3.04 % 4.10 % To estimate the interest cost component of the net periodic benefit expense for the Pension Plan, the Company utilizes a full yield curve approach by applying specific spot rates along the yield curve used in the determination of the benefit obligation to the relevant projected cash flows. To the extent the cumulative actuarial losses included in accumulated other comprehensive loss exceed 10% of the greater of the accumulated benefit obligation or the market-related value of the Pension Plan assets, it is the Company's policy to amortize the Pension Plan's net actuarial losses into income over the average remaining life expectancy of the Pension Plan participants. Actuarial losses included in accumulated other comprehensive loss as of December 31, 2019 exceeded 10% of the accumulated benefit obligation and the fair value of Pension Plan assets. The amortization of net actuarial losses is a component of the net periodic benefit cost. Amortization of the net actuarial losses and prior service cost included in other comprehensive income (loss) is not expected to have a material impact on the Company's future results of operations, financial position, or liquidity. Net Periodic Benefit Pension Cost (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Components of net periodic benefit cost Interest cost $ 1,841 $ 2,031 $ 1,712 Expected return on plan assets (4,642) (3,820) (3,802) Recognized net actuarial loss 531 533 591 Amortization of prior service cost — — — Recognized settlement loss 1,781 2,703 2,480 Net periodic (income) cost (489) 1,447 981 Other changes in plan assets and benefit obligations recognized as Net gain (loss) for the period 1,313 (7,086) (83) Amortization of net loss 2,311 3,236 3,071 Total unrealized gain (loss) 3,624 (3,850) 2,988 Total recognized in net periodic pension cost and other $ 4,113 $ (5,297) $ 2,007 Weighted-average assumptions used to determine the net periodic cost Discount rate 4.10 % 3.45 % 3.86 % Expected return on plan assets 5.75 % 5.75 % 6.25 % Pension Plan Asset Allocation (Dollar amounts in thousands) Percentage of Plan Assets as of December 31, Target Allocation Fair Value of Plan Assets (1) 2019 2018 Asset Category Equity securities 50 - 65% $ 54,800 59 % 61 % Fixed income 25 - 55% 33,976 37 % 37 % Cash equivalents 0 - 10% 3,514 4 % 2 % Total $ 92,290 100 % 100 % (1) Additional information regarding the fair value of Pension Plan assets as of December 31, 2019 can be found in Note 22, "Fair Value." The expected long-term rate of return on Pension Plan assets represents the average rate of return expected to be earned over the period the benefits included in the benefit obligation are to be paid. In developing the expected rate of return, the Company considers long-term returns based on historical market data and projections of future returns for each asset category, as well as historical actual returns on the Pension Plan assets with the assistance of its independent actuarial consultant. Using this reference data, the Company develops a forward-looking return expectation for each asset category and a weighted-average expected long-term rate of return based on the target asset allocation. The investment objective of the Pension Plan is to maximize the return on Pension Plan assets over a long-term horizon to satisfy the Pension Plan obligations. In establishing its investment and asset allocation strategies, the Company considers expected returns and the volatility associated with different strategies. The investment strategies established by the Company's Retirement Plan Committee provide for growth of capital with a moderate level of volatility by investing assets according to the target allocations stated above and reallocating those assets as needed to stay within those allocations. Investments are weighted toward publicly traded securities. Investment strategies that include alternative asset classes, such as private equity hedge funds and real estate, are generally avoided. The following table presents estimated future pension benefit payments under the Pension Plan for retirees already receiving benefits and future retirees, assuming they retire and begin receiving unreduced benefits as soon as they are eligible. Estimated Future Pension Benefit Payments (Dollar amounts in thousands) Year ending December 31, 2020 $ 8,478 2021 5,300 2022 5,872 2023 4,497 2024 4,977 2025-2028 20,844

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	SHARE-BASED COMPENSATION The Company maintains various equity-based compensation plans in order to grant equity awards to certain key employees and non-employee directors. Share-Based Plans First Midwest Bancorp, Inc. 2018 Stock and Incentive Plan ("2018 Stock and Incentive Plan") – In May of 2018, the Company's stockholders approved the 2018 Stock and Incentive Plan, which succeeds the Omnibus Stock and Incentive Plan ("Omnibus Plan") described below, under which the Company has ceased making new awards. The Company's stockholders authorized an additional 2,000,000 shares of the Company's common stock for award under the 2018 Stock and Incentive Plan, with the remaining shares eligible for issuance under the Omnibus Plan now being eligible for issuance under the 2018 Stock and Incentive Plan. The 2018 Stock and Incentive Plan allows for the grant of both incentive and non-statutory ("nonqualified") stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, and performance units to certain key employees. The Company's current equity compensation program for key employees includes restricted stock, restricted stock units, and performance shares. Both restricted stock and restricted stock unit awards vest over three For participants who are granted performance shares, they may earn performance shares totaling between 0% and 200% of the number of performance shares granted based on achieving certain performance metrics. Performance shares may be earned based on achieving an internal metric (core return on average tangible common equity) and an external metric (relative total shareholder return) over a three Omnibus Plan – In 1989, the Board adopted the Omnibus Plan, which allowed for the grant of both incentive and nonqualified stock options, stock appreciation rights, restricted stock, restricted stock units, performance units, and other awards to certain key employees. Effective May 16, 2018, the Omnibus Plan has been succeeded by the 2018 Stock and Incentive Plan and the Company no longer makes awards under the Omnibus Plan. Shares eligible for issuance under the Omnibus Plan at the time the 2018 Stock and Incentive Plan was approved by the Company's stockholders were transferred to the 2018 Stock and Incentive Plan. All outstanding equity awards granted prior to the approval of the 2018 Stock and Incentive Plan will continue to be governed by the Omnibus Plan. Nonemployee Directors Stock Plan (the "Directors Plan") – In 1997, the Board adopted the Directors Plan, which provides for the grant of equity awards to non-management Board members. In 2008, the Company amended the Directors Plan to allow for the grant of restricted stock awards, among other items. Since 2015, non-management members receive fully vested shares of the Company's common stock rather than restricted stock. The 2018 Stock and Incentive Plan, the Omnibus Plan, and the Directors Plan, and material amendments, were submitted to and approved by the stockholders of the Company. The Company issues treasury shares to satisfy the vesting of restricted stock, restricted stock units, and performance share awards. Shares of Common Stock Available Under Share-Based Plans As of December 31, 2019 Shares Authorized Shares Available For Grant 2018 Stock and Incentive Plan (1) 3,295,590 2,648,229 Directors Plan 481,250 102,989 (1) The shares of the Company's common stock underlying all outstanding equity awards governed by the Omnibus Plan that are canceled, forfeited, or expire will be available for issuance under the 2018 Stock and Incentive Plan. Restricted Stock, Restricted Stock Unit, and Performance Share Awards Restricted Stock, Restricted Stock Unit, and Performance Share Award Transactions (Amounts in thousands, except per share data) Year Ended December 31, 2019 Restricted Stock/Unit Awards Performance Shares Number of Shares/Units Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Non-vested awards beginning balance 947 $ 23.32 468 $ 19.88 Granted 497 23.04 146 23.04 Vested (417) 21.13 (94) 21.13 Forfeited (35) 24.20 (19) 24.20 Non-vested awards ending balance 992 $ 24.03 501 $ 20.40 In addition, non-management board members received, in the aggregate, 14,000 shares of common stock for both the years ended December 31, 2019 and 2018, respectively. Other Restricted Stock, Restricted Stock Unit, and Performance Share Award Information (Amounts in thousands, except per share data) Years Ended December 31, 2019 2018 2017 Weighted-average grant date fair value of restricted stock, restricted stock unit, and performance share awards granted during the year $ 23.04 $ 24.96 $ 24.71 Total fair value of restricted stock, restricted stock unit, and performance share awards vested during the year 13,092 10,870 13,760 Income tax benefit realized from the vesting/release of restricted stock, restricted stock unit, and performance share awards 2,920 2,970 4,007 No restricted stock, restricted stock unit, or performance share award modifications were made during the periods presented. Compensation Expense The Company recognizes share-based compensation expense based on the estimated fair value of the award at the grant or modification date. Share-based compensation expense is included in salaries and wages in the Consolidated Statements of Income. Effect of Recording Share-Based Compensation Expense (Dollar amounts in thousands) Years ended December 31, 2019 2018 2017 Total share-based compensation expense (1) $ 13,183 $ 12,062 $ 11,223 Income tax benefit 3,678 3,365 4,601 Share-based compensation expense, net of tax $ 9,505 $ 8,697 $ 6,622 Unrecognized compensation expense $ 14,299 $ 13,982 $ 13,266 Weighted-average amortization period remaining (in years) 1.1 1.2 1.3 (1) Comprised of restricted stock, restricted stock unit, and performance share awards expense.

Regulatory and Capital Matters

Regulatory and Capital Matters	12 Months Ended
	Dec. 31, 2019
Banking and Thrift [Abstract]
Regulatory and Capital Matters	REGULATORY AND CAPITAL MATTERS The Company and its subsidiaries are subject to various regulatory requirements that impose restrictions on cash, loans or advances, and dividends. The Bank is also required to maintain reserves against deposits. Reserves are held either in the form of vault cash or noninterest-bearing balances maintained with the FRB and are based on the average daily balances and statutory reserve ratios prescribed by the type of deposit account. Reserve balances totaling $135.4 million as of December 31, 2019 and $149.2 million as of December 31, 2018 were maintained in accordance with these requirements. Under current Federal Reserve regulations, the Bank is limited in the amount it may loan or advance to First Midwest Bancorp, Inc. on an unconsolidated basis (the "Parent Company") and its non-bank subsidiaries. Loans or advances to a single subsidiary may not exceed 10%, and loans to all subsidiaries may not exceed 20%, of the Bank's capital stock and surplus. Loans from subsidiary banks to non-bank subsidiaries, including the Parent Company, are also required to be collateralized. The principal source of cash flow for the Parent Company is dividends from the Bank. Various federal and state banking regulations and capital guidelines limit the amount of dividends that the Bank may pay to the Parent Company. Without prior regulatory approval and while maintaining its well-capitalized status, the Bank can initiate aggregate dividend payments in 2020 of $91.4 million plus its net profits for 2020, as defined by statute, up to the date of any such dividend declaration. Future payment of dividends by the Bank depends on individual regulatory capital requirements and levels of profitability. The Company and the Bank are also subject to various capital requirements set up and administered by federal banking agencies. Under capital adequacy guidelines, the Company and the Bank must meet specific guidelines that involve quantitative measures given the risk levels of assets and certain off-balance sheet items calculated under regulatory accounting practices ("risk-weighted assets"). The capital amounts and classification are also subject to qualitative judgments by the regulators regarding components of capital and assets, risk weightings, and other factors. The Federal Reserve, the primary regulator of the Company and the Bank, establishes minimum capital requirements that must be met by the Company and the Bank. As defined in the regulations, quantitative measures established by regulation to ensure capital adequacy require the Company and the Bank to maintain minimum amounts and ratios of total capital to risk-weighted assets, Tier 1 capital to risk-weighted assets, common equity Tier 1 capital ("CET1") to risk-weighted assets, and Tier 1 capital to adjusted average assets. Failure to meet minimum capital requirements could result in actions by regulators that could have a material adverse effect on the Company's financial statements. As of December 31, 2019, the Company and the Bank met all capital adequacy requirements. As of December 31, 2019, the Bank was "well-capitalized" under the regulatory framework for prompt corrective action. There are no conditions or events since that management believes would change the Bank's classification. The following table outlines the Company's and the Bank's measures of capital as of the dates presented and the capital guidelines established by the Federal Reserve for the Company and the Bank to be categorized as adequately capitalized and avoid limitations on certain distributions, as well as for the Bank to be categorized as "well-capitalized." Summary of Regulatory Capital Ratios (Dollar amounts in thousands) Actual Adequately Capitalized To Be Well-Capitalized Under Prompt Corrective Action Provisions Capital Ratio % Capital Ratio % Capital Ratio % As of December 31, 2019 Total capital to risk-weighted assets: First Midwest Bancorp, Inc. $ 1,843,597 12.96 $ 1,493,672 10.500 N/A N/A First Midwest Bank 1,598,886 11.28 1,488,796 10.500 $ 1,417,901 10.00 Tier 1 capital to risk-weighted assets: First Midwest Bancorp, Inc. 1,496,048 10.52 1,209,163 8.500 N/A N/A First Midwest Bank 1,489,664 10.51 1,205,215 8.500 1,134,320 8.00 CET1 to risk-weighted assets: First Midwest Bancorp, Inc. 1,496,048 10.52 995,781 7.000 N/A N/A First Midwest Bank 1,489,664 10.51 992,530 7.000 921,635 6.50 Tier 1 capital to average assets: First Midwest Bancorp, Inc. 1,496,048 8.81 679,365 4.000 N/A N/A First Midwest Bank 1,489,664 8.79 677,570 4.000 846,963 5.00 As of December 31, 2018 Total capital to risk-weighted assets: First Midwest Bancorp, Inc. $ 1,626,489 12.62 $ 1,273,103 9.875 N/A N/A First Midwest Bank 1,463,026 11.39 1,268,662 9.875 $ 1,284,721 10.00 Tier 1 capital to risk-weighted assets: First Midwest Bancorp, Inc. 1,315,098 10.20 1,015,259 7.875 N/A N/A First Midwest Bank 1,359,607 10.58 1,011,718 7.875 1,027,777 8.00 CET1 to risk-weighted assets: First Midwest Bancorp, Inc. 1,315,432 10.20 821,876 6.375 N/A N/A First Midwest Bank 1,359,607 10.58 819,009 6.375 835,068 6.50 Tier 1 capital to average assets: First Midwest Bancorp, Inc. 1,315,098 8.90 591,293 4.000 N/A N/A First Midwest Bank 1,359,607 9.41 577,991 4.000 722,488 5.00 N/A – Not applicable. In July of 2013, the Federal Reserve published final rules (the "Basel III Capital Rules") implementing the Basel III framework set forth by the Basel Committee on Banking Supervision (the "Basel Committee"). The phase-in period for the final rules began for the Company on January 1, 2015, and was completed on January 1, 2019. Since full phase-in on January 1, 2019, the Basel III Capital Rules have required the Company and the Bank to maintain the following: • A minimum ratio of CET1 to risk-weighted assets of at least 4.5%, plus a 2.5% "capital conservation buffer" (resulting in a minimum ratio of CET1 to risk-weighted assets of at least 7.0%). • A minimum ratio of Tier 1 capital to risk-weighted assets of at least 6.0%, plus the capital conservation buffer (resulting in a minimum Tier 1 capital ratio of 8.5%). • A minimum ratio of total capital (Tier 1 capital plus Tier 2 capital) to risk-weighted assets of at least 8.0%, plus the capital conservation buffer (resulting in a minimum total capital ratio of 10.5%). • A minimum leverage ratio of 4.0%, calculated as the ratio of Tier 1 capital to average assets. The Basel III Capital Rules also provide for a number of deductions from and adjustments to CET1 that were phased-in over a four In July of 2019, federal bank regulators adopted final rules intended to simplify the capital treatment for certain deferred tax assets, mortgage servicing assets, investments in non-consolidated financial entities and minority interests for banking organizations, such as the Company and the Bank, that are not subject to the advanced approaches framework (the "Capital Simplification Rules"). The Capital Simplification Rules and the rescission of the Transition Rule took effect for the Company as of January 1, 2020. In December of 2017, the Basel Committee published standards that it described as the finalization of the Basel III post-crisis regulatory reforms (the standards are commonly referred to as "Basel IV"). Among other things, these standards revise the Basel Committee's standardized approach for credit risk (including the recalibration of risk weights and introducing new capital requirements for certain "unconditionally cancellable commitments," such as unused credit card lines of credit) and provide a new standardized approach for operational risk capital. Under the Basel framework, these standards will generally be effective on January 1, 2022, with an aggregate output floor phasing in through January 1, 2027. Under the current U.S. capital rules, operational risk capital requirements and a capital floor apply only to advanced approaches banking organizations and not to the Company or the Bank. The impact of Basel IV on the Company and the Bank will depend on the manner in which it is implemented by the federal bank regulators.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES In the ordinary course of business, the Company enters into derivative transactions as part of its overall interest rate risk management strategy. The significant accounting policies related to derivative instruments and hedging activities are presented in Note 1, "Summary of Significant Accounting Policies." Cash Flow Hedges As of December 31, 2019, the Company hedged $815.0 million of certain corporate variable rate loans using interest rate swaps through which the Company receives fixed amounts and pays variable amounts. The Company also hedged $1.1 billion of borrowed funds using forward starting interest rate swaps through which the Company receives variable amounts and pays fixed amounts. These transactions allow the Company to add stability to net interest income and manage its exposure to interest rate movements. Forward starting interest rate swaps totaling $560.0 million began on various dates between February of 2017 and December of 2019, and mature between February of 2020 and September of 2022. The remaining forward starting interest rate swaps totaling $530.0 million begin on various dates between February of 2020 and February of 2021 and mature between February of 2022 and August of 2024. The weighted-average fixed interest rate to be paid on these interest rate swaps that have not yet begun was 2.13% as of December 31, 2019. These derivative contracts are designated as cash flow hedges. Cash Flow Hedges (Dollar amounts in thousands) As of December 31, 2019 2018 Gross notional amount outstanding $ 1,905,000 $ 2,280,000 Derivative asset fair value in other assets (1) 727 6,889 Derivative liability fair value in other liabilities (1) (119) (11,328) Weighted-average interest rate received 1.88 % 2.12 % Weighted-average interest rate paid 1.74 % 2.20 % Weighted-average maturity (in years) 1.18 1.53 (1) Certain cash flow hedges are transacted through a clearinghouse ("centrally cleared") and their change in fair value is settled by the counterparties to the transaction, which results in no fair value. Changes in the fair value of cash flow hedges are recorded in accumulated other comprehensive income (loss) on an after-tax basis and are subsequently reclassified to interest income or expense in the period that the forecasted hedged item impacts earnings. As of December 31, 2019, the Company estimates that $1.0 million will be reclassified from accumulated other comprehensive loss as an increase to interest income over the next twelve months. Other Derivative Instruments The Company also enters into derivative transactions through capital market products with its commercial customers and simultaneously enters into an offsetting interest rate derivative transaction with third-parties. This transaction allows the Company's customers to effectively convert a variable rate loan into a fixed rate loan. Due to the offsetting nature of these transactions, the Company does not apply hedge accounting treatment. The Company's credit exposure on these derivative transactions results primarily from counterparty credit risk. The credit valuation adjustment ("CVA") is a fair value adjustment to the derivative to account for this risk. As of December 31, 2019 and 2018, the Company's credit exposure was fully secured by the underlying collateral on customer loans and mitigated through netting arrangements with third-parties; therefore, no CVA was recorded. Capital market products income related to commercial customer derivative instruments of $13.9 million, $7.7 million, and $8.2 million was recorded in noninterest income for the years ended December 31, 2019, 2018, and 2017, respectively. Other Derivative Instruments (Dollar amounts in thousands) As of December 31, 2019 2018 Gross notional amount outstanding $ 4,340,384 $ 3,085,226 Derivative asset fair value in other assets (1) 61,709 25,168 Derivative liability fair value in other liabilities (1) (18,416) (17,533) Fair value of derivative (2) 18,856 18,013 (1) Certain other derivative instruments are centrally cleared and their change in fair value is settled by the counterparties to the transaction, which results in no fair value. (2) This amount represents the fair value if credit risk related contingent factors were triggered. The Company occasionally enters into risk participation agreements with counterparty banks to transfer or assume a portion of the credit risk related to customer transactions. The amounts of these instruments were not material for any period presented. The Company had no other derivative instruments as of December 31, 2019 and 2018. The Company does not enter into derivative transactions for purely speculative purposes. The following table presents the impact of derivative instruments on comprehensive income and the reclassification of gains (losses) from accumulated other comprehensive loss to net interest income for the years ended December 31, 2019 and 2018, and 2017. Cash Flow Hedge Accounting on Accumulated Other Comprehensive Income (Dollar amounts in thousands) Years Ended December 30, 2019 2018 2017 Gains (losses) recognized in other comprehensive income Interest rate swaps in interest income $ 13,236 $ 18,776 $ 11,150 Interest rate swaps in interest expense (16,873) (20,500) (8,025) Reclassification of gains (losses) included in net income Interest rate swaps in interest income $ 3,975 $ 2,611 $ 5,159 Interest rate swaps in interest expense (5,008) (3,673) (3,951) The following table presents the impact of derivative instruments on net interest income for the years ended December 31, 2019, 2018, and 2017. Hedge Income (Dollar amounts in thousands) Years Ended December 30, 2019 2018 2017 Cash Flow Hedges Interest rate swaps in interest income 3,975 2,611 5,159 Interest rate swaps in interest expense (5,008) (3,673) (3,951) Total cash flow hedges (1,033) (1,062) 1,208 Credit Risk Derivative instruments are inherently subject to credit risk, which represents the Company's risk of loss when the counterparty to a derivative contract fails to perform according to the terms of the agreement. Credit risk is managed by limiting and collateralizing the aggregate amount of net unrealized losses by transaction, monitoring the size and the maturity structure of the derivatives, and applying uniform credit standards. Company policy establishes limits on credit exposure to any single counterparty. In addition, the Company established bilateral collateral agreements with derivative counterparties that provide for exchanges of marketable securities or cash to collateralize either party's net losses above a stated minimum threshold. As of December 31, 2019 and 2018, these collateral agreements covered 100% of the fair value of the Company's outstanding derivatives. Derivative assets and liabilities are presented gross, rather than net, of pledged collateral amounts. Certain derivative instruments are subject to master netting agreements with counterparties. The Company records these transactions at their gross fair values and does not offset derivative assets and liabilities in the Consolidated Statements of Financial Condition. The following table presents the fair value of the Company's derivatives and offsetting positions as of December 31, 2019 and 2018. Fair Value of Offsetting Derivatives (Dollar amounts in thousands) As of December 31, 2019 2018 Assets Liabilities Assets Liabilities Gross amounts recognized $ 62,436 $ 18,535 $ 32,057 $ 28,861 Less: amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition (1) 62,436 18,535 32,057 28,861 Gross amounts not offset in the Consolidated Statements of Financial Condition: Offsetting derivative positions (2,674) (2,674) (11,678) (11,678) Cash collateral pledged — (15,861) (9,060) (3,506) Net credit exposure $ 59,762 $ — $ 11,319 $ 13,677 (1) Included in other assets or other liabilities in the Consolidated Statements of Financial Condition. As of December 31, 2019 and 2018, the Company's derivative instruments generally contained provisions that require the Company's debt to remain above a certain credit rating by each of the major credit rating agencies or that the Company maintain certain capital levels. If the Company's debt were to fall below that credit rating or the Company's capital were to fall below the required levels, it would be in violation of those provisions, and the counterparties to the derivative instruments could terminate the swap transaction and demand cash settlement of the derivative instrument in an amount equal to the derivative liability fair value. As of December 31, 2019 and 2018, the Company was in compliance with these provisions.

Commitments, Guarantees, and Co

Commitments, Guarantees, and Contingent Liabilities	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments, Guarantees, and Contingent Liabilities	COMMITMENTS, GUARANTEES, AND CONTINGENT LIABILITIES Credit Commitments and Guarantees In the normal course of business, the Company enters into a variety of financial instruments with off-balance sheet risk to meet the financing needs of its customers and to conduct lending activities, including commitments to extend credit as well as standby and commercial letters of credit. These instruments involve elements of credit and interest rate risk in excess of the amount recognized in the Consolidated Statements of Financial Condition. Contractual or Notional Amounts of Financial Instruments (Dollar amounts in thousands) As of December 31, 2019 2018 Commitments to extend credit: Commercial, industrial, and agricultural $ 1,852,040 $ 1,729,286 Commercial real estate 296,053 296,882 Home equity 576,956 570,553 Other commitments (1) 251,093 244,917 Total commitments to extend credit $ 2,976,142 $ 2,841,638 Letters of credit $ 103,684 $ 112,728 (1) Other commitments includes installment and overdraft protection program commitments. Commitments to extend credit are agreements to lend funds to a customer, subject to contractual terms and covenants. Commitments generally have fixed expiration dates or other termination clauses, variable interest rates, and fee requirements, when applicable. Since many of the commitments are expected to expire without being drawn, the total commitment amounts do not necessarily represent future cash flow requirements. In the event of a customer's non-performance, the Company's credit loss exposure is equal to the contractual amount of the commitments. The credit risk is essentially the same as extending loans to customers for the full contractual amount. The Company uses the same credit policies for credit commitments as its loans and minimizes exposure to credit loss through various collateral requirements. Letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third-party. Letters of credit generally are contingent on the failure of the customer to perform according to the terms of the contract with the third-party and are often issued in favor of a municipality where construction is taking place to ensure the borrower adequately completes the construction. Commercial letters of credit are issued to facilitate transactions between a customer and a third-party based on agreed upon terms. The maximum potential future payments guaranteed by the Company under letters of credit arrangements are equal to the contractual amount of the commitment. If a commitment is funded, the Company may seek recourse through the liquidation of the underlying collateral, including real estate, production plants and property, marketable securities, or receipt of cash. As a result of the sale of certain 1-4 family mortgage loans, the Company is contractually obligated to repurchase early payment default loans or loans that do not meet underwriting requirements at recorded value. In accordance with the sales agreements, there is no limitation to the maximum potential future payments or expiration of the Company's recourse obligation. There were no material loan repurchases during the years ended December 31, 2019 or 2018. Legal Proceedings In the ordinary course of business, there were certain legal proceedings pending against the Company and its subsidiaries at December 31, 2019. While the outcome of any legal proceeding is inherently uncertain, based on information currently available, the Company's management does not expect that any liabilities arising from pending legal matters will have a material adverse effect on the Company's business, financial condition, or results of operations.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value	FAIR VALUE Fair value represents the amount expected to be received to sell an asset or paid to transfer a liability in its principal or most advantageous market in an orderly transaction between market participants at the measurement date. In accordance with fair value accounting guidance, the Company measures, records, and reports various types of assets and liabilities at fair value on either a recurring or non-recurring basis in the Consolidated Statements of Financial Condition. Those assets and liabilities are presented below in the sections titled "Assets and Liabilities Required to be Measured at Fair Value on a Recurring Basis" and "Assets and Liabilities Required to be Measured at Fair Value on a Non-Recurring Basis." Other assets and liabilities are not required to be measured at fair value in the Consolidated Statements of Financial Condition, but must be disclosed at fair value. See the "Fair Value Measurements of Other Financial Instruments" section of this note. Any aggregation of the estimated fair values presented in this note does not represent the value of the Company. Depending on the nature of the asset or liability, the Company uses various valuation methodologies and assumptions to estimate fair value. GAAP provides a three-tiered fair value hierarchy based on the inputs used to measure fair value. The hierarchy is defined as follows: • Level 1 – Quoted prices in active markets for identical assets or liabilities. • Level 2 – Observable inputs other than level 1 prices, such as quoted prices for similar instruments, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs require significant management judgment or estimation, some of which use model-based techniques and may be internally developed. Assets and liabilities are assigned to a level within the fair value hierarchy based on the lowest level of significant input used to measure fair value. Assets and liabilities may change levels within the fair value hierarchy due to market conditions or other circumstances. Those transfers are recognized on the date of the event that prompted the transfer. There were no transfers of assets or liabilities required to be measured at fair value on a recurring basis between levels of the fair value hierarchy during the periods presented. Assets and Liabilities Required to be Measured at Fair Value on a Recurring Basis The following table provides the fair value for assets and liabilities required to be measured at fair value on a recurring basis in the Consolidated Statements of Financial Condition by level in the fair value hierarchy. Recurring Fair Value Measurements (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets Equity securities $ 23,703 $ 13,400 $ — $ 19,658 $ 11,148 $ — Securities available-for-sale U.S. treasury securities 34,075 — — 37,767 — — U.S. agency securities — 248,424 — — 142,563 — CMOs — 1,557,671 — — 1,315,209 — MBSs — 684,684 — — 466,934 — Municipal securities — 234,431 — — 227,187 — Corporate debt securities — 114,101 — — 82,349 — Total securities available-for-sale 34,075 2,839,311 — 37,767 2,234,242 — Mortgage servicing rights ("MSRs") (1) — — 5,858 — — 6,730 Derivative assets (1) — 62,436 — — 32,057 — Liabilities Derivative liabilities (2) $ — $ 18,535 $ — $ — $ 28,861 $ — (1) Included in other assets in the Consolidated Statements of Financial Condition. (2) Included in other liabilities in the Consolidated Statements of Financial Condition. The following sections describe the specific valuation techniques and inputs used to measure financial assets and liabilities at fair value. Equity Securities The Company's equity securities consist primarily of community development investments and certain diversified investment securities held in a grantor trust for participants in the Company's nonqualified deferred compensation plan that are invested in money market and mutual funds. The fair value of certain community development investments is based on quoted prices in active markets or market prices for similar securities obtained from external pricing services or dealer market participants and is classified in level 2 of the fair value hierarchy. As of December 31, 2019, the fair value of certain community development investments totaling $5.0 million was based on the net asset value per share ("NAV") practical expedient and can be redeemed at any month end with 30 days notice. Since these investments are measured at fair value using the NAV practical expedient, they are not classified in the fair value hierarchy. The fair value of the money market and mutual funds is based on quoted market prices in active exchange markets and is classified in level 1 of the fair value hierarchy. Securities Available-for-Sale The Company's securities available-for-sale are primarily fixed income instruments that are not quoted on an exchange, but may be traded in active markets. The fair values for these securities are based on quoted prices in active markets or market prices for similar securities obtained from external pricing services or dealer market participants and are classified in level 2 in the fair value hierarchy. The fair value of U.S. treasury securities is based on quoted market prices in active exchange markets and is classified in level 1 of the fair value hierarchy. Quarterly, the Company evaluates the methodologies used by its external pricing services to estimate the fair value of these securities to determine whether the valuations represent an exit price in the Company's principal markets. The Company liquidated all of its remaining CDOs during 2017. A rollforward of the carrying value of CDOs for the year ended December 31, 2017 is presented in the following table. Carrying Value of CDOs (Dollar amounts in thousands) Years Ended December 31, 2017 Beginning balance $ 33,260 Additions — Change in other comprehensive income (1) 14,421 Paydowns and sales (47,681) Ending balance $ — (1) Included in unrealized holding gains (losses) in the Consolidated Statements of Comprehensive Income. Mortgage Servicing Rights The Company services loans for others totaling $653.7 million and $627.3 million as of December 31, 2019 and 2018, respectively. These loans are owned by third-parties and are not included in the Consolidated Statements of Financial Condition. The Company determines the fair value of MSRs by estimating the present value of expected future cash flows associated with the mortgage loans being serviced and classifies them in level 3 of the fair value hierarchy. The following table presents the ranges of significant, unobservable inputs used by the Company to determine the fair value of MSRs as of December 31, 2019 and 2018. Significant Unobservable Inputs Used in the Valuation of MSRs As of December 31, 2019 2018 Prepayment speed 6.7 % - 12.0% 6.5 % - 13.5% Maturity (months) 18 - 94 20 - 104 Discount rate 9.3 % - 12.0% 9.5 % - 12.0% The impact of changes in these key inputs could result in a significantly higher or lower fair value measurement for MSRs. Significant increases in expected prepayment speeds and discount rates have negative impacts on the valuation. Higher maturity assumptions have a favorable effect on the estimated fair value. A rollforward of the carrying value of MSRs for the three years ended December 31, 2019 is presented in the following table. Carrying Value of MSRs (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 6,730 $ 5,894 $ 6,120 New MSRs 1,228 1,080 673 Total (losses) gains included in earnings (1) : Changes in valuation inputs and assumptions (1,559) 475 (41) Other changes in fair value (2) (541) (719) (858) Ending balance (3) $ 5,858 $ 6,730 $ 5,894 Contractual servicing fees earned during the year (1) $ 1,586 $ 1,517 $ 1,536 Total amount of loans being serviced for the benefit of 653,656 627,323 607,016 (1) Included in mortgage banking income in the Consolidated Statements of Income and related to assets held as of December 31, 2019, 2018, and 2017. (2) Primarily represents changes in expected future cash flows over time due to payoffs and paydowns. (3) Included in other assets in the Consolidated Statements of Financial Condition. Derivative Assets and Derivative Liabilities The Company enters into interest rate swaps and derivative transactions with commercial customers. These derivative transactions are executed in the dealer market, and pricing is based on market quotes obtained from the counterparties. The market quotes were developed using market observable inputs, which primarily include LIBOR. Therefore, derivatives are classified in level 2 of the fair value hierarchy. For its derivative assets and liabilities, the Company also considers non-performance risk, including the likelihood of default by itself and its counterparties, when evaluating whether the market quotes from the counterparties are representative of an exit price. Pension Plan Assets Although Pension Plan assets are not consolidated in the Company's Consolidated Statements of Financial Condition, they are required to be measured at fair value on an annual basis. The fair value of Pension Plan assets is presented in the following table by level in the fair value hierarchy. Annual Fair Value Measurements for Pension Plan Assets (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Level 1 Level 2 Total Level 1 Level 2 Total Pension plan assets: Mutual funds (1) $ 34,231 $ — $ 34,231 $ 27,246 $ — $ 27,246 U.S. government and government agency securities 3,720 3,685 7,405 4,389 3,626 8,015 Corporate bonds — 10,865 10,865 — 10,472 10,472 Common stocks 34,693 — 34,693 26,882 — 26,882 Common trust funds N/A N/A 5,096 N/A N/A 3,595 Total pension plan assets $ 72,644 $ 14,550 $ 92,290 $ 58,517 $ 14,098 $ 76,210 N/A – Not applicable for investments measured at fair value using net asset value ("NAV") as a practical expedient which are not classified in the fair value hierarchy. (1) Includes mutual funds, money market funds, cash, cash equivalents, and accrued interest. Mutual funds, certain U.S. government agency securities, and common stocks are based on quoted market prices in active exchange markets and classified in level 1 of the fair value hierarchy. Corporate bonds and certain U.S. government and government agency securities are valued at quoted prices from independent sources that are based on observable market trades or observable prices for similar bonds where a price for the identical bond is not observable and, therefore, are classified in level 2 of the fair value hierarchy. Common trust funds are valued at NAV on the last business day of the Pension Plan's year end, which is used as a practical expedient to estimate fair value. The NAV is based on the value of the underlying assets owned by the fund, minus its liabilities, divided by the number of units outstanding. Since these investments are measured at fair value using the NAV as a practical expedient, they are not classified in the fair value hierarchy. There were no Pension Plan assets classified in level 3 of the fair value hierarchy. Assets and Liabilities Required to be Measured at Fair Value on a Non-Recurring Basis The following table provides the fair value for each class of assets and liabilities required to be measured at fair value on a non-recurring basis in the Consolidated Statements of Financial Condition by level in the fair value hierarchy. Non-Recurring Fair Value Measurements (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Collateral-dependent impaired loans (1) $ — $ — $ 41,326 $ — $ — $ 24,565 OREO (2) — — 3,325 — — 6,012 Loans held-for-sale (3) — — 36,032 — — 3,478 Assets held-for-sale (4) — — 6,824 — — 3,722 (1) Includes impaired loans with charge-offs and impaired loans with a specific reserve during the periods presented. (2) Includes OREO with fair value adjustments subsequent to initial transfer that occurred during the periods presented. (3) Included in other assets in the Consolidated Statements of Financial Condition. (4) Included in premises, furniture, and equipment in the Consolidated Statements of Financial Condition. Collateral-Dependent Impaired Loans Certain collateral-dependent impaired loans are subject to fair value adjustments to reflect the difference between the carrying value of the loan and the value of the underlying collateral. The fair values of collateral-dependent impaired loans are primarily determined by current appraised values of the underlying collateral. Based on the age and/or type, appraisals may be adjusted in the range of 0% to 15%. In certain cases, an internal valuation may be used when the underlying collateral is located in areas where comparable sales data is limited or unavailable. Accordingly, collateral-dependent impaired loans are classified in level 3 of the fair value hierarchy. Collateral-dependent impaired loans for which the fair value is greater than the recorded investment are not measured at fair value in the Consolidated Statements of Financial Condition and are not included in this disclosure. OREO The fair value of OREO is measured using the current appraised value of the properties. In certain circumstances, a current appraisal may not be available or may not represent an accurate measurement of the property's fair value due to outdated market information or other factors. In these cases, the fair value is determined based on the lower of the (i) most recent appraised value, (ii) broker price opinion, (iii) current listing price, or (iv) signed sales contract. Given these valuation methods, OREO is classified in level 3 of the fair value hierarchy. Loans Held-for-Sale Loans held-for-sale consists of 1-4 family mortgage loans, which were originated with the intent to sell as of December 31, 2019 and 2018. These loans were recorded in the held-for-sale category at the contract price, which approximates fair value, and, accordingly, are classified in level 3 of the fair value hierarchy. Assets Held-for-Sale As of December 31, 2019, assets held-for-sale consists of former branches that are no longer in operation and parcels of land previously purchased for expansion. These properties are being actively marketed and were transferred into the held-for-sale category at their fair value as determined by current appraisals. Based on these valuation methods, they are classified in level 3 of the fair value hierarchy. Goodwill and Other Intangible Assets Goodwill and other intangible assets are subject to annual impairment testing, which requires a significant degree of management judgment. If the testing had resulted in impairment, the Company would have classified goodwill and other intangible assets in level 3 of the fair value hierarchy as a non-recurring fair value measurement. Additional information regarding goodwill, other intangible assets, and impairment policies can be found in Note 1, "Summary of Significant Accounting Policies," and Note 10, "Goodwill and Other Intangible Assets." Financial Instruments Not Required to be Measured at Fair Value For certain financial instruments that are not required to be measured at fair value in the Consolidated Statements of Financial Condition, the Company must disclose the estimated fair values and the level within the fair value hierarchy as shown in the following table. Fair Value Measurements of Other Financial Instruments (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Fair Value Hierarchy Carrying Fair Value Carrying Fair Value Assets Cash and due from banks 1 $ 214,894 $ 214,894 $ 211,189 $ 211,189 Interest-bearing deposits in other banks 2 84,327 84,327 78,069 78,069 Securities held-to-maturity 2 21,997 21,234 10,176 9,871 FHLB and FRB stock 2 115,409 115,409 80,302 80,302 Loans 3 12,733,200 12,535,848 11,346,668 11,052,040 Investment in BOLI 3 296,351 296,351 296,733 296,733 Accrued interest receivable 3 59,716 59,716 54,847 54,847 Other interest-earning assets 3 — — 5 5 Liabilities Deposits 2 $ 13,251,278 $ 13,247,871 $ 12,084,112 $ 12,064,604 Borrowed funds 2 1,658,758 1,658,758 906,079 906,079 Senior and subordinated debt 2 233,948 277,203 203,808 211,207 Accrued interest payable 2 10,502 10,502 10,005 10,005 Management uses various methodologies and assumptions to determine the estimated fair values of the financial instruments in the table above. The fair value estimates are made at a discrete point in time based on relevant market information and consider management's judgments regarding future expected economic conditions, loss experience, and specific risk characteristics of the financial instruments. Loans include the FDIC indemnification asset and net loans, which consists of loans held-for-investment, acquired loans, and the allowance for loan losses. As of both December 31, 2019 and 2018, the Company estimated the fair value of lending commitments outstanding to be immaterial.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS The Company, through the Bank, makes loans to and has transactions with certain of its directors and executive officers. All of these loans and transactions were made on substantially the same terms, including interest rates and collateral requirements, for comparable transactions with unrelated persons and did not involve more than the normal risk of collectability or present unfavorable features. For the years ended December 31, 2019 and 2018, loans to directors and executive officers were not greater than 5% of stockholders' equity.

Condensed Parent Company Financ

Condensed Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Parent Company Financial Statements	CONDENSED PARENT COMPANY FINANCIAL STATEMENTS The following represents the condensed financial statements of First Midwest Bancorp, Inc., the Parent Company. Statements of Financial Condition (Parent Company only) (Dollar amounts in thousands) As of December 31, 2019 2018 Assets Cash and due from banks $ 247,507 $ 158,026 Investments in and advances to subsidiaries 2,360,467 2,091,158 Other assets 45,306 55,782 Total assets $ 2,653,280 $ 2,304,966 Liabilities and Stockholders' Equity Senior and subordinated debt $ 233,948 $ 203,808 Accrued interest payable and other liabilities 48,539 46,160 Stockholders' equity 2,370,793 2,054,998 Total liabilities and stockholders' equity $ 2,653,280 $ 2,304,966 Statements of Income (Parent Company only) (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Income Dividends from subsidiaries $ 236,137 $ 86,095 $ 74,091 Interest income 613 453 2,211 Securities transactions and other 23 280 (1,372) Total income 236,773 86,828 74,930 Expenses Interest expense 14,431 12,708 12,428 Salaries and employee benefits 13,903 22,430 20,978 Other expenses 11,384 9,440 9,126 Total expenses 39,718 44,578 42,532 Income before income tax benefit and equity in undistributed income of subsidiaries 197,055 42,250 32,398 Income tax benefit 10,609 13,299 14,851 Income before equity in undistributed income of subsidiaries 207,664 55,549 47,249 Equity in undistributed (loss) income of subsidiaries (7,926) 102,321 51,138 Net income 199,738 157,870 98,387 Net income applicable to non-vested restricted shares (1,681) (1,312) (916) Net income applicable to common shares $ 198,057 $ 156,558 $ 97,471 Statements of Cash Flows (Parent Company only) (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Operating Activities Net income $ 199,738 $ 157,870 $ 98,387 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed loss (income) of subsidiaries 7,926 (102,321) (51,138) Depreciation of premises, furniture, and equipment 51 42 9 Net securities losses — — 1,523 Share-based compensation expense 13,183 12,062 11,223 Tax benefit related to share-based compensation 364 258 349 Net (increase) decrease in other assets (67,330) 35,981 18,667 Net increase (decrease) in other liabilities 49,813 (17,942) (52,377) Net cash provided by operating activities 203,745 85,950 26,643 Investing Activities Proceeds from sales and maturities of securities available-for-sale — — 42,516 Purchase of premises, furniture, and equipment — (61) (119) Net cash (paid) received for acquisitions (19,966) 39 (47,364) Net cash used in investing activities (19,966) (22) (4,967) Financing Activities Repurchases of common stock (33,928) — — Cash dividends paid (56,540) (44,293) (37,129) Restricted stock activity (3,830) (4,421) (3,952) Net cash used in financing activities (94,298) (48,714) (41,081) Net increase (decrease) in cash and cash equivalents 89,481 37,214 (19,405) Cash and cash equivalents at beginning of year 158,026 120,812 140,217 Cash and cash equivalents at end of year $ 247,507 $ 158,026 $ 120,812 Supplemental Disclosures of Cash Flow Information: Common stock issued for acquisitions, net of issuance costs $ 101,496 $ 83,303 $ 534,090

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Nature of Operations and Basis of Presentation	Nature of Operations – First Midwest Bancorp, Inc. (the "Company") is a bank holding company that was incorporated in Delaware in 1982 and began operations on March 31, 1983. The Company is headquartered in Chicago, Illinois with operations throughout metropolitan Chicago, southeast Wisconsin, northwest Indiana, central and western Illinois, and eastern Iowa. The Company operates three wholly-owned subsidiaries: First Midwest Bank (the "Bank"), Northern Oak Wealth Management, Inc. ("Northern Oak"), and Premier Asset Management LLC ("Premier"). The Bank conducts the majority of the Company's operations and Northern Oak and Premier are registered investment advisers providing advisory services to certain of the Company's wealth management clients. The Company is engaged in commercial and consumer banking and offers a full range of commercial, treasury management, equipment leasing, consumer, wealth management, trust, and private banking products and services.
Reclassification	Certain reclassifications were made to prior year amounts to conform to the current year presentation.
Use of Estimates	Use of Estimates – The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Although these estimates and assumptions are based on the best available information, actual results could differ from those estimates.
Principles of Consolidation	Principles of Consolidation – The accompanying consolidated financial statements include the financial position and results of operations of the Company and its subsidiaries after elimination of all significant intercompany accounts and transactions. Assets held in a fiduciary or agency capacity are not assets of the Company or its subsidiaries and are not included in the consolidated financial statements.
Segment Disclosures	Segment Disclosures – The Company has one reportable segment. The Company's chief operating decision maker evaluates the operations of the Company using consolidated information for purposes of allocating resources and assessing performance. Therefore, segment disclosures are not required.
Business Combinations	Business Combinations – Business combinations are accounted for under the acquisition method of accounting. Assets acquired and liabilities assumed are recorded at their estimated fair values as of the date of acquisition, with any excess of the purchase price of the acquisition over the fair value of the identifiable net tangible and intangible assets acquired recorded as goodwill. Alternatively, a gain is recorded if the fair value of assets purchased exceeds the fair value of liabilities assumed and consideration paid. The results of operations of the acquired business are included in the Consolidated Statements of Income from the effective date of the acquisition.
Cash and Cash Equivalents	Cash and Cash Equivalents – For purposes of the Consolidated Statements of Cash Flows, management defines cash and cash equivalents to include cash and due from banks, interest-bearing deposits in other banks, and other short-term investments, if any, such as federal funds sold and securities purchased under agreements to resell.
Securities	Securities – Securities are classified as held-to-maturity, equity, or available-for-sale at the time of purchase. Securities Held-to-Maturity – Securities classified as held-to-maturity are securities for which management has the intent and ability to hold to maturity. These securities are stated at cost and adjusted for amortization of premiums and accretion of discounts over the estimated lives of the securities using the effective interest method. Equity Securities – The Company's equity securities consist primarily of community development investments and certain diversified investment securities held in a grantor trust for participants in the Company's nonqualified deferred compensation plan that are invested in money market and mutual funds. These securities are carried at fair value with changes in fair value recognized in net income. Securities Available-for-Sale – All other securities are classified as available-for-sale. Securities available-for-sale are carried at fair value with unrealized gains and losses, net of related deferred income taxes, recorded in stockholders' equity as a separate component of accumulated other comprehensive loss. The historical cost of debt securities is adjusted for amortization of premiums and accretion of discounts over the estimated life of the security using the effective interest method. Amortization of premiums and accretion of discounts are included in interest income. Purchases and sales of securities are recognized on a trade date basis. Realized securities gains or losses are reported in net securities losses in the Consolidated Statements of Income. The cost of securities sold is based on the specific identification method. On a quarterly basis, the Company individually assesses securities with unrealized losses to determine whether there were any events or circumstances indicating that an other-than-temporary impairment ("OTTI") has occurred. In evaluating OTTI, the Company considers many factors, including (i) the severity and duration of the impairment, (ii) the financial condition and near-term prospects of the issuer, including external credit ratings and recent downgrades for debt securities, (iii) its intent to hold the security until its value recovers, and (iv) the likelihood that it will be required to sell the security before a recovery in value, which may be at maturity. If management intends to sell the security or believes it is more likely than not that it will be required to sell the security prior to full recovery, an OTTI charge will be recognized through income as a realized loss and included in net securities losses in the Consolidated Statements of Income. If management does not expect to sell the security or believes it is not more likely than not that it will be required to sell the security prior to full recovery, the OTTI is separated into the amount related to credit deterioration, which is recognized through income as a realized loss, and the amount resulting from other factors, which is recognized in other comprehensive income.
FHLB and FRB Stock	FHLB and FRB Stock – The Company, as a member of the FHLB and FRB, is required to maintain an investment in the capital stock of the FHLB and FRB. No ready market exists for these stocks, and they have no quoted market values. The stock is redeemable at par by the FHLB and FRB and is, therefore, carried at cost and periodically evaluated for impairment.
Loans	Loans – Loans held-for-investment are loans that the Company intends to hold until they are paid in full and are carried at the principal amount outstanding, including certain net deferred loan origination fees. Loan origination fees, commitment fees, and certain direct loan origination costs are deferred, and the net amount is amortized as a yield adjustment over the contractual life of the related loans or commitments and included in interest income. Fees related to letters of credit are amortized into fee income over the contractual life of the commitment. Other credit-related fees are recognized as fee income when earned. The Company's net investment in direct financing leases is included in loans and consists of future minimum lease payments and estimated residual values, net of unearned income. Interest income on loans is accrued based on principal amounts outstanding. Loans held-for-sale are carried at the lower of aggregate cost or fair value and included in other assets in the Consolidated Statements of Financial Condition.
Acquired and Covered Loans	Acquired and Covered Loans – Covered loans consist of loans acquired by the Company in Federal Deposit Insurance Corporation ("FDIC")-assisted transactions, which are covered by loss share agreements with the FDIC (the "FDIC Agreements"), under which the FDIC reimburses the Company for the majority of the losses and eligible expenses related to these assets during the coverage period. Acquired loans consist of all other loans that were acquired in business combinations that are not covered by the FDIC Agreements. Certain loans that were previously classified as covered loans are no longer covered under the FDIC Agreements, and are included in acquired loans. Covered loans and acquired loans are included within loans held-for-investment. Acquired and covered loans are separated into (i) non-purchased credit impaired ("non-PCI") and (ii) purchased credit impaired ("PCI") loans. Non-PCI loans include loans that did not have evidence of credit deterioration since origination at the acquisition date. PCI loans include loans that had evidence of credit deterioration since origination and for which it was probable at acquisition that the Company would not collect all contractually required principal and interest payments. Evidence of credit deterioration was evaluated using various indicators, such as past due and non-accrual status. Leases and revolving loans do not qualify to be accounted for as PCI loans and are accounted for as non-PCI loans. The acquisition adjustment related to non-PCI loans is amortized into interest income over the contractual life of the related loans. If an acquired non-PCI loan is renewed subsequent to the acquisition date, any remaining acquisition adjustment is accreted into interest income and the loan is considered a new loan that is no longer classified as an acquired loan. PCI loans are accounted for based on estimates of expected future cash flows. To estimate the fair value, the Company generally aggregates purchased consumer loans and commercial loans into pools of loans with common risk characteristics, such as delinquency status, credit score, and internal risk ratings. The fair values of larger balance commercial loans are estimated on an individual basis. The Company use a discounted cash flow analysis involving significant unobservable inputs and assumptions to measure the fair value of PCI loans. The significant assumptions utilized in the cash flow analysis include the probability of default ("PD"), loss given default ("LGD"), and discount rate. Expected future cash flows in excess of the fair value of loans at the purchase date ("accretable yield") are recorded as interest income over the life of the loans if the timing and amount of the expected future cash flows can be reasonably estimated. The non-accretable yield represents the difference between contractually required payments and the expected future cash flows determined at acquisition. Subsequent increases in expected future cash flows are offset against the allowance for credit losses to the extent an allowance has been established or
90-Days Past Due Loans	90-Days Past Due Loans – The Company's accrual of interest on loans is generally discontinued at the time the loan is 90 days past due unless the credit is sufficiently collateralized and in the process of renewal or collection.
Non-accrual Loans	Non-accrual Loans – Generally, corporate loans are placed on non-accrual status (i) when either principal or interest payments become 90 days or more past due unless the credit is sufficiently collateralized and in the process of renewal or collection, or (ii) when an individual analysis of a borrower's creditworthiness warrants a downgrade to non-accrual regardless of past due status. When a loan is placed on non-accrual status, unpaid interest credited to income in the current year is reversed, and unpaid interest accrued in prior years is charged against the allowance for loan losses. After the loan is placed on non-accrual status, all debt service payments are applied to the principal on the loan. Future interest income may only be recorded on a cash basis after recovery of principal is reasonably assured. Non-accrual loans are returned to accrual status when the financial position of the borrower and other relevant factors indicate that the Company will collect all principal and interest. Commercial loans and loans secured by real estate are charged-off when deemed uncollectible. A loss is recorded if the net realizable value of the underlying collateral is less than the outstanding principal and interest. Consumer loans that are not secured by real estate are subject to mandatory charge-off at a specified delinquency date and are usually not classified as non-accrual prior to being charged-off. Closed-end consumer loans, which include installment, consumer secured, and single payment loans, are usually charged-off no later than the end of the month in which the loan becomes 120 days past due. PCI loans are generally considered accruing loans unless reasonable estimates of the timing and amount of expected future cash flows cannot be determined. Loans without reasonable future cash flow estimates are classified as non-accrual loans, and interest income is not recognized on those loans until the timing and amount of the expected future cash flows can be reasonably determined.
Troubled Debt Restructurings (TDRs)	Troubled Debt Restructurings ("TDRs") – A restructuring is considered a TDR when (i) the borrower is experiencing financial difficulties, and (ii) the creditor grants a concession, such as forgiveness of principal, reduction of the interest rate, changes in payments, or extension of the maturity date. Loans are not classified as TDRs when the modification is short-term or results in an insignificant delay in payments. The Company's TDRs are determined on a case-by-case basis. The Company does not accrue interest on a TDR unless it believes collection of all principal and interest under the modified terms is reasonably assured. For a TDR to begin accruing interest, the borrower must demonstrate some level of past performance and the future capacity to perform under the modified terms. Generally, six months of consecutive payment performance under the restructured terms is required before a TDR is returned to accrual status. However, the period could vary depending on the individual facts and circumstances of the loan. An evaluation of the borrower's current creditworthiness is used to assess the borrower's capacity to repay the loan under the modified terms. This evaluation includes an estimate of expected future cash flows, evidence of strong financial position, and estimates of the value of collateral, if applicable. For TDRs to be removed from TDR status in the calendar year after the restructuring, the loans must (i) have an interest rate and terms that reflect market conditions at the time of restructuring, and (ii) be in compliance with the modified terms. If the loan was restructured at below market rates and terms, it continues to be separately reported as a TDR until it is paid in full or charged-off.
Impaired Loans	Impaired Loans – Impaired loans consist of corporate non-accrual loans and TDRs. A loan is considered impaired when it is probable that the Company will not collect all contractual principal and interest. With the exception of accruing TDRs, impaired loans are classified as non-accrual and are exclusive of smaller homogeneous loans, such as home equity, 1-4 family mortgages, and installment loans. Impaired loans with balances under a specified threshold are not individually evaluated for impairment. For all other impaired loans, impairment is measured by comparing the estimated value of the loan to the recorded book value. The value of collateral-dependent loans is based on the fair value of the underlying collateral, less costs to sell. The value of other loans is measured using the present value of expected future cash flows discounted at the loan's initial effective interest rate.
Allowance for Credit Losses and Allowance for Loan Losses	Allowance for Credit Losses – The allowance for credit losses is comprised of the allowance for loan losses and the reserve for unfunded commitments, and is maintained by management at a level believed adequate to absorb estimated losses inherent in the existing loan portfolio. Determination of the allowance for credit losses is subjective since it requires significant estimates and management judgment, including the amounts and timing of expected future cash flows on impaired loans, estimated losses on pools of homogeneous loans, consideration of current economic trends, and other factors. Loans deemed to be uncollectible are charged-off against the allowance for loan losses, while recoveries of amounts previously charged-off are credited to the allowance for loan losses. Additions to the allowance for loan losses are charged to expense through the provision for loan losses. The amount of provision depends on a number of factors, including net charge-off levels, loan growth, changes in the composition of the loan portfolio, and the Company's assessment of the allowance for loan losses based on the methodology discussed below. Allowance for Loan Losses – The allowance for loan losses consists of (i) specific reserves for individual loans where the recorded investment exceeds the value, (ii) an allowance based on a loss migration analysis that uses historical credit loss experience for each loan category, and (iii) an allowance based on other internal and external qualitative factors. The specific reserves component of the allowance for loan losses is based on a periodic analysis of impaired loans exceeding a fixed dollar amount. If the value of an impaired loan is less than the recorded book value, the Company either establishes a valuation allowance (i.e., a specific reserve) equal to the excess of the book value over the collateral value of the loan as a component of the allowance for loan losses or charges off the amount if it is a confirmed loss. The general reserve component is based on a loss migration analysis, which examines actual loss experience by loan category for a rolling 8-quarter period and the related internal risk rating for corporate loans. The loss migration analysis is updated quarterly primarily using actual loss experience. This component is then adjusted based on management's consideration of many internal and external qualitative factors, including: • Changes in the composition of the loan portfolio, trends in the volume of loans, and trends in delinquent and non-accrual loans that could indicate that historical trends do not reflect current conditions. • Changes in credit policies and procedures, such as underwriting standards and collection, charge-off, and recovery practices. • Changes in the experience, ability, and depth of credit management and other relevant staff. • Changes in the quality of the Company's loan review system and Board of Directors oversight. • The effect of any concentration of credit and changes in the level of concentrations, such as loan type or risk rating. • Changes in the value of the underlying collateral for collateral-dependent loans. • Changes in the national and local economy that affect the collectability of various segments of the portfolio. • The effect of other external factors, such as competition and legal and regulatory requirements, on the Company's loan portfolio. The allowance for loan losses also consists of an allowance on acquired and covered non-PCI and PCI loans. No allowance for loan losses is recorded on acquired loans at the acquisition date. Subsequent to the acquisition date, an allowance for credit losses is established as necessary to reflect credit deterioration. The acquired non-PCI allowance is based on management's evaluation of the acquired non-PCI loan portfolio giving consideration to the current portfolio balance, including the remaining acquisition adjustments, maturity dates, and overall credit quality. The allowance for covered non-PCI loans is calculated in the same manner as the general reserve component based on a loss migration analysis as discussed above. The acquired and covered PCI allowance reflects the difference between the carrying value and the discounted expected future cash flows of the acquired and covered PCI loans. On a periodic basis, the adequacy of this allowance is determined through a re-estimation of expected future cash flows on all of the outstanding acquired and covered PCI loans using either a PD/LGD methodology or a specific review methodology. The PD/LGD model is a loss model that estimates expected future cash flows using a probability of default curve and loss given default estimates. Acquired non-PCI loans that have renewed subsequent to the respective acquisition dates are no longer classified as acquired loans. Instead, they are included in the general loan population and allocated an allowance based on a loss migration analysis. Reserve for Unfunded Commitments – The Company also maintains a reserve for unfunded commitments, including letters of credit, for the risk of loss inherent in these arrangements. The reserve for unfunded commitments is estimated using the loss migration analysis from the allowance for loan losses, adjusted for probabilities of future funding requirements. The reserve for unfunded commitments is included in other liabilities in the Consolidated Statements of Financial Condition. The establishment of the allowance for credit losses involves a high degree of judgment and estimation given the difficulty of assessing the factors impacting loan repayment and estimating the timing and amount of losses. While management utilizes its best judgment and information available, the adequacy of the allowance for credit losses depends on a variety of factors beyond the Company's control, including the performance of its loan portfolio, current national and local economic trends, changes in interest rates and property values, the amounts and timing of expected future cash flows on impaired loans, estimated losses on pools of homogeneous loans, the interpretation of loan risk classifications by regulatory authorities, and various internal and external qualitative factors.
OREO	OREO – OREO consists of properties acquired through foreclosure in partial or total satisfaction of defaulted loans. At initial transfer into OREO, properties are recorded at fair value, less estimated selling costs. Subsequently, OREO is carried at the lower of the cost basis or fair value, less estimated selling costs. OREO write-downs occurring at the transfer date are charged against the allowance for loan losses, establishing a new cost basis. Subsequent to the initial transfer, the carrying values of OREO may be adjusted through a valuation allowance to reflect reductions in value resulting from new appraisals, new list
FDIC Indemnification Asset	FDIC Indemnification Asset – The majority of loans and OREO acquired through FDIC-assisted transactions are covered by the FDIC Agreements, under which the FDIC reimburses the Company for the majority of the losses and eligible expenses related to these assets during the coverage period. The FDIC indemnification asset represents the present value of expected future reimbursements from the FDIC. Since the indemnified items are covered loans and covered OREO, which are initially measured at fair value, the FDIC indemnification asset is also initially measured at fair value by discounting the expected future cash flows to be received from the FDIC. These expected future cash flows are estimated by multiplying estimated losses on covered PCI loans and covered OREO by the reimbursement rates in the FDIC Agreements. The balance of the FDIC indemnification asset is adjusted periodically to reflect changes in expected future cash flows. Decreases in estimated reimbursements from the FDIC are recorded prospectively through amortization and increases in estimated reimbursements from the FDIC are recognized by an increase in the carrying value of the indemnification asset. Payments from the FDIC for reimbursement of losses result in a reduction of the FDIC indemnification asset.
Depreciable Assets	Depreciable Assets – Premises, furniture, and equipment are stated at cost, less accumulated depreciation. Depreciation expense is determined by the straight-line method over the estimated useful lives of the assets. Useful lives range from 3 to 10 years for furniture and equipment and 25 to 40 years for premises. Leasehold improvements are amortized over the shorter of the life of the asset or the lease term. Gains on dispositions are included in other noninterest income and losses on dispositions are included in other noninterest expense in the Consolidated Statements of Income. Maintenance and repairs are charged to operating expenses as incurred, while improvements that extend the useful life of assets are capitalized and depreciated over the estimated remaining life. Certain assets, such as buildings and land, that the Company intends to sell and meet held-for-sale criteria are transferred into the held-for-sale category at the lower of their fair value, as determined by a current appraisal, or their recorded investment. Long-lived depreciable assets are evaluated periodically for impairment when events or changes in circumstances indicate the carrying amount may not be recoverable. Impairment exists when the undiscounted expected future cash flows of a long-lived asset are less than its carrying value. In that event, the Company recognizes a loss for the difference between the carrying amount and the estimated fair value of the asset based on a quoted market price, if applicable, or a discounted cash flow analysis. Impairment losses are recorded in other noninterest expense in the Consolidated Statements of Income.
BOLI	BOLI – BOLI represents life insurance policies on the lives of certain Company directors and officers for which the Company is the sole owner and beneficiary. These policies are recorded as an asset in the Consolidated Statements of Financial Condition at their cash surrender value ("CSV") or the current amount that could be realized if settled. The change in CSV and insurance proceeds received are included as a component of noninterest income in the Consolidated Statements of Income.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets – Goodwill represents the excess of the purchase price of the acquisition over the fair value of the net tangible and intangible assets acquired using the acquisition method of accounting. Goodwill is not amortized. Instead, impairment testing is conducted annually as of October 1 or more often if events or circumstances between annual tests indicate that there may be impairment. Impairment testing is performed using either a qualitative or quantitative approach at the reporting unit level. All of the Company's goodwill is allocated to First Midwest Bancorp, Inc., which is the Company's only applicable reporting unit for purposes of testing goodwill for impairment. Impairment testing performed using a qualitative approach assesses recent events and circumstances to determine whether it is more-likely-than-not that the fair value of a reporting unit is less than its carrying amount. Qualitative factors include, but are not limited to, macroeconomic conditions, industry- and market- specific conditions and trends, the Company's financial performance, market capitalization, stock price, and Company-specific events relevant to the assessment. If the assessment of qualitative factors indicates that it is not more-likely-than-not that an impairment exists, no further testing is performed; otherwise, the Company would proceed with a quantitative two-step goodwill impairment test. In the first step, the Company compares its estimate of the fair value of the reporting unit, which is based on a discounted cash flow analysis, with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired and the second step is not required. If necessary, the second step compares the implied fair value of the reporting unit goodwill with the carrying amount of that goodwill. The implied fair value of goodwill is determined by assigning the value of the reporting unit to all of the assets and liabilities of that unit, including any other identifiable intangible assets. An impairment loss is recognized if the carrying amount of the reporting unit goodwill exceeds the implied fair value of goodwill. Other intangible assets represent purchased assets that lack physical substance, but can be distinguished from goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged either on its own or in
Wealth Management	Wealth Management – Assets held in a fiduciary or agency capacity for customers are not included in the consolidated financial statements as they are not assets of the Company or its subsidiaries. Fee income is recognized on an accrual basis and is included as a component of noninterest income in the Consolidated Statements of Income.
Derivative Financial Instruments	Derivative Financial Instruments – To provide derivative products to customers and in the ordinary course of business, the Company enters into derivative transactions as part of its overall interest rate risk management strategy to minimize significant unplanned fluctuations in earnings and expected future cash flows caused by interest rate volatility. All derivative instruments are recorded at fair value as either other assets or other liabilities in the Consolidated Statements of Financial Condition. Subsequent changes in a derivative's fair value are recognized in earnings unless specific hedge accounting criteria are met. On the date the Company enters into a derivative contract, the derivative is designated as a fair value hedge, a cash flow hedge, or a non-hedge derivative instrument. Fair value hedges are designed to mitigate exposure to changes in the fair value of an asset or liability attributable to a particular risk, such as interest rate risk. Cash flow hedges are designed to mitigate exposure to variability in expected future cash flows to be received or paid related to an asset, liability, or other type of forecasted transaction. The Company formally documents all relationships between hedging instruments and hedged items, including its risk management objective and strategy at inception. At the hedge's inception and quarterly thereafter, a formal assessment is performed to determine the effectiveness of the derivative in offsetting changes in the fair values or expected future cash flows of the hedged items in the current period and prospectively. If a derivative instrument designated as a hedge is terminated or ceases to be highly effective, hedge accounting is discontinued prospectively, and the gain or loss is amortized into earnings. For fair value hedges, the gain or loss is amortized over the remaining life of the hedged asset or liability. For cash flow hedges, the gain or loss is amortized over the same period that the forecasted hedged transactions impact earnings. If the hedged item is disposed of, any fair value adjustments are included in the gain or loss from the disposition of the hedged item. If the forecasted transaction is no longer probable, the gain or loss is included in earnings immediately. For fair value hedges, changes in the fair value of the derivative instruments, as well as changes in the fair value of the hedged item, are recognized in earnings. For cash flow hedges, the effective portion of the change in fair value of the derivative instrument is reported as a component of accumulated other comprehensive loss and is reclassified to earnings when the hedged transaction is reflected in earnings. Ineffectiveness is calculated based on the change in fair value of the hedged item compared with the change in fair value of the hedging instrument. For all types of hedges, any ineffectiveness in the hedging relationship is recognized in earnings during the period the ineffectiveness occurs.
Comprehensive Income	Comprehensive Income – Comprehensive income is the total of reported net income and other comprehensive income (loss) that includes all other revenues, expenses, gains, and losses that are not reported in net income under GAAP. The Company includes the following items, net of tax, in other comprehensive income (loss) in the Consolidated Statements of Comprehensive Income: (i) changes in unrealized gains or losses on securities available-for-sale, (ii) changes in the fair value of derivatives designated as cash flow hedges, and (iii) changes in unrecognized net pension costs related to the Company's pension plan.
Treasury Stock	Treasury Stock – Treasury stock acquired is recorded at cost and is carried as a reduction of stockholders' equity in the Consolidated Statements of Financial Condition. Treasury stock issued is valued based on the "last in, first out" inventory method. The difference between the consideration received on issuance and the carrying value is charged or credited to additional paid-in capital.
Share-Based Compensation	Share-Based Compensation – The Company recognizes share-based compensation expense based on the estimated fair value of the award at the grant or modification date over the period during which an employee is required to provide service in exchange for such award. Share-based compensation expense is included in salaries and wages in the Consolidated Statements of Income.
Income Taxes	Income Taxes – The Company files U.S. federal income tax returns and state income tax returns in various states. The provision for income taxes is based on income in the consolidated financial statements, rather than amounts reported on the Company's income tax return.
Earnings per Common Share	Earnings per Common Share – EPS is computed using the two-class method. Basic EPS is computed by dividing net income applicable to common shares by the weighted-average number of common shares outstanding during the applicable period, excluding outstanding participating securities. Participating securities include non-vested restricted stock awards and restricted stock units, which contain nonforfeitable rights to dividends or dividend equivalents. Diluted earnings per common share is computed using the weighted-average number of shares determined for the basic earnings per common share computation, plus the dilutive effect of stock compensation using the treasury stock method.
Adopted Accounting Pronouncements and Accounting Pronouncements Pending Adoption	Adopted Accounting Pronouncements Leases: In February of 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02 to increase transparency and comparability across entities for leasing arrangements. This guidance requires lessees to recognize assets and liabilities for most leases. For lessors, this guidance modifies the lease classification criteria and the accounting for sales-type and direct financing leases. In addition, this guidance clarifies criteria for the determination of whether a contract is or contains a lease. This guidance is effective for annual and interim periods beginning after December 15, 2018. The Company adopted this guidance on January 1, 2019, which resulted in the recognition of $143.6 million of right-of-use assets and additional associated lease liabilities for its operating leases. The amount of right-of-use assets and associated lease liabilities recorded upon adoption was based on the present value of future minimum lease payments, the amount of which depended on the population of leases in effect at the date of adoption. This guidance also applies to the Company's net investment in direct financing leases, which is included in loans, but did not have a material impact. The Company has elected certain practical expedients contained in this guidance, which, among other provisions, allowed the Company to not reassess the historical lease classification, initial direct costs, or existing contracts for the inclusion of leases. The Company has also elected the practical expedients for the use of hindsight in determining the lease term and the right-of-use assets, as well as an election not to apply the recognition requirements of the guidance to leases with terms of 12 months or less. The application of the hindsight practical expedient resulted in the determination that most renewal options would not be reasonably certain in determining the expected lease term. The Bank entered into a sale-leaseback transaction in 2016 that resulted in a deferred gain. Upon adoption of this guidance, the remaining deferred gain of $47.3 million after-tax was recognized immediately as a cumulative-effect adjustment to equity. For additional discussion of the sale-leaseback transaction, see Note 9, "Lease Obligations." The adoption of this guidance was applied retrospectively at the beginning of the period of adoption through a cumulative-effect adjustment and did not materially impact the Company's results of operations or liquidity but did result in a material increase in assets, liabilities, and equity. Premium Amortization on Purchased Callable Debt Securities: In March of 2017, the FASB issued ASU 2017-08 that shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. This guidance is effective for annual and interim periods beginning after December 15, 2018. The adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Improvements to Nonemployee Share-based Payment Accounting: In June of 2018, the FASB issued ASU 2018-07 that aligns the measurement and classification guidance for share-based payments to nonemployees with the guidance for share-based payments to employees. This guidance is effective for annual and interim periods beginning after December 15, 2018. The adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract: In August of 2018, the FASB issued ASU 2018-15 to reduce diversity in practice by clarifying when implementation costs are required to be capitalized in a cloud computing arrangement that is a service contract. This guidance is effective for annual and interim periods beginning after December 15, 2019. The early adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Derivatives and Hedging, Inclusion of the Secured Overnight Financing Rate ("SOFR") Overnight Index Swap Rate as a Benchmark Interest Rate for Hedge Accounting Purposes: In October of 2018, the FASB issued ASU 2018-16 adding the overnight index swap rate based on the SOFR to the list of United States benchmark interest rates eligible for hedge accounting purposes. This guidance is effective for annual and interim periods beginning after December 15, 2018. The adoption of this guidance on January 1, 2019 did not materially impact the Company's financial condition, results of operations, or liquidity. Accounting Pronouncements Pending Adoption Measurement of Credit Losses on Financial Instruments: In June of 2016, the FASB issued ASU 2016-13 that will require entities to present financial assets measured at amortized cost at the net amount expected to be collected, considering an entity's current estimate of all expected credit losses. In addition, credit losses relating to available-for-sale debt securities will be required to be recorded through an allowance for credit losses, with changes in credit loss estimates recognized through current earnings. This guidance is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted, but not for periods beginning before December 15, 2018. The Company will adopt this guidance on January 1, 2020. Management is continuing its implementation efforts, which are led by a cross-functional working group. Management is in the process of determining the impact on the Company's financial condition, results of operations, liquidity, and regulatory capital ratios, but expects that the adoption of this guidance will result in an increase in the allowance for credit losses. The extent of the increase will depend on the composition of the loan portfolio, as well as the economic conditions and forecasts as of the adoption date. Management has completed its development of the forecasting model for all portfolio segments, which includes the establishment of economic factors, a one-year forecast period, and a one-year reversion to the historical average after the forecast period. Management will continue to evaluate and refine the overall process as well as its internal controls through the first quarter of 2020. Accounting for Goodwill Impairment: In January of 2017, the FASB issued ASU 2017-04 that simplifies the accounting for goodwill impairment for all entities. The new guidance eliminates the requirement to calculate the implied fair value of goodwill using the second step of the quantitative two-step goodwill impairment model prescribed under current accounting guidance. Under the new guidance, if a reporting unit's carrying amount exceeds its fair value, an entity will record an impairment charge based on that difference. This guidance is effective for annual and interim goodwill impairment testing dates beginning after December 15, 2019. Early adoption is permitted for annual and interim goodwill impairment testing dates after January 1, 2017. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity. Changes to the Disclosure Requirements for Fair Value Measurement: In August of 2018, the FASB issued ASU 2018-13 that eliminates, modifies, and adds to certain fair value measurement disclosure requirements associated with the three-tiered fair value hierarchy. This guidance is effective for annual and interim periods beginning after December 15, 2019. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity. Changes to the Disclosure Requirements for Defined Benefit Plans: In August of 2018, the FASB issued ASU 2018-14 that makes minor changes and clarifications to the disclosure requirements for entities that sponsor defined benefit plans. This guidance is effective for annual and interim periods beginning after December 15, 2020. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity. Income Taxes: In December of 2019, the FASB issued ASU 2019-12 that removes certain exceptions to the general principles of accounting for income taxes. This guidance is effective for fiscal year, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity.
Pension and Other Postretirement Plans	To the extent the cumulative actuarial losses included in accumulated other comprehensive loss exceed 10% of the greater of the accumulated benefit obligation or the market-related value of the Pension Plan assets, it is the Company's policy to amortize the Pension Plan's net actuarial losses into income over the average remaining life expectancy of the Pension Plan participants. Actuarial losses included in accumulated other comprehensive loss as of December 31, 2019 exceeded 10% of the accumulated benefit obligation and the fair value of Pension Plan assets. The amortization of net actuarial losses is a component of the net periodic benefit cost. Amortization of the net actuarial losses and prior service cost included in other comprehensive income (loss) is not expected to have a material impact on the Company's future results of operations, financial position, or liquidity.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of Acquisition Activity	The following table presents the assets acquired and liabilities assumed, net of the fair value adjustments, in the Bridgeview and Northern States transactions as of the acquisition date. The assets acquired and liabilities assumed, both intangible and tangible, were recorded at their estimated fair values as of the acquisition date and have been accounted for under the acquisition method of accounting. Acquisition Activity (Dollar amounts in thousands, except share and per share data) Bridgeview Northern States May 9, 2019 October 12, 2018 Assets Cash and due from banks and interest-bearing deposits in other banks $ 35,097 160,145 Equity securities 6,966 3,915 Securities available-for-sale 263,090 47,149 Securities held-to-maturity 13,426 — FHLB and FRB stock 1,481 554 Loans 710,647 284,940 OREO 6,003 2,549 Investment in BOLI — 11,104 Goodwill 59,142 30,016 Other intangible assets 15,603 12,230 Premises, furniture, and equipment 17,681 5,820 Accrued interest receivable and other assets 35,997 20,911 Total assets $ 1,165,133 $ 579,333 Liabilities Noninterest-bearing deposits $ 179,267 $ 346,714 Interest-bearing deposits 807,487 116,446 Total deposits 986,754 463,160 Borrowed funds 1,746 18,218 Senior and subordinated debt 29,360 8,038 Accrued interest payable and other liabilities 11,921 6,614 Total liabilities 1,029,781 496,030 Consideration Paid Common stock (2019 - 4,728,541, shares issued at $28.61 per share, 2018 - 3,310,912 share issued at $25.16 per share), net of issuance costs 98,212 83,303 Cash paid 37,140 — Total consideration paid 135,352 83,303 $ 1,165,133 $ 579,333

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	A summary of the Company's securities portfolio by category and maturity is presented in the following tables. Securities Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 33,939 $ 137 $ (1) $ 34,075 $ 37,925 $ 17 $ (175) $ 37,767 U.S. agency securities 249,502 758 (1,836) 248,424 144,125 45 (1,607) 142,563 Collateralized mortgage 1,547,805 14,893 (5,027) 1,557,671 1,336,531 3,362 (24,684) 1,315,209 Other mortgage-backed 678,804 7,728 (1,848) 684,684 477,665 520 (11,251) 466,934 Municipal securities 228,632 5,898 (99) 234,431 229,600 461 (2,874) 227,187 Corporate debt securities 112,797 1,791 (487) 114,101 86,074 — (3,725) 82,349 Total securities available-for-sale $ 2,851,479 $ 31,205 $ (9,298) $ 2,873,386 $ 2,311,920 $ 4,405 $ (44,316) $ 2,272,009 Securities Held-to-Maturity Municipal securities $ 21,997 $ — $ (763) $ 21,234 $ 10,176 $ — $ (305) $ 9,871 Equity Securities $ 42,136 $ 30,806
Securities Available-for-Sale	A summary of the Company's securities portfolio by category and maturity is presented in the following tables. Securities Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 33,939 $ 137 $ (1) $ 34,075 $ 37,925 $ 17 $ (175) $ 37,767 U.S. agency securities 249,502 758 (1,836) 248,424 144,125 45 (1,607) 142,563 Collateralized mortgage 1,547,805 14,893 (5,027) 1,557,671 1,336,531 3,362 (24,684) 1,315,209 Other mortgage-backed 678,804 7,728 (1,848) 684,684 477,665 520 (11,251) 466,934 Municipal securities 228,632 5,898 (99) 234,431 229,600 461 (2,874) 227,187 Corporate debt securities 112,797 1,791 (487) 114,101 86,074 — (3,725) 82,349 Total securities available-for-sale $ 2,851,479 $ 31,205 $ (9,298) $ 2,873,386 $ 2,311,920 $ 4,405 $ (44,316) $ 2,272,009 Securities Held-to-Maturity Municipal securities $ 21,997 $ — $ (763) $ 21,234 $ 10,176 $ — $ (305) $ 9,871 Equity Securities $ 42,136 $ 30,806
Securities Held-to-Maturity	A summary of the Company's securities portfolio by category and maturity is presented in the following tables. Securities Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 33,939 $ 137 $ (1) $ 34,075 $ 37,925 $ 17 $ (175) $ 37,767 U.S. agency securities 249,502 758 (1,836) 248,424 144,125 45 (1,607) 142,563 Collateralized mortgage 1,547,805 14,893 (5,027) 1,557,671 1,336,531 3,362 (24,684) 1,315,209 Other mortgage-backed 678,804 7,728 (1,848) 684,684 477,665 520 (11,251) 466,934 Municipal securities 228,632 5,898 (99) 234,431 229,600 461 (2,874) 227,187 Corporate debt securities 112,797 1,791 (487) 114,101 86,074 — (3,725) 82,349 Total securities available-for-sale $ 2,851,479 $ 31,205 $ (9,298) $ 2,873,386 $ 2,311,920 $ 4,405 $ (44,316) $ 2,272,009 Securities Held-to-Maturity Municipal securities $ 21,997 $ — $ (763) $ 21,234 $ 10,176 $ — $ (305) $ 9,871 Equity Securities $ 42,136 $ 30,806
Trading Securities	A summary of the Company's securities portfolio by category and maturity is presented in the following tables. Securities Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 33,939 $ 137 $ (1) $ 34,075 $ 37,925 $ 17 $ (175) $ 37,767 U.S. agency securities 249,502 758 (1,836) 248,424 144,125 45 (1,607) 142,563 Collateralized mortgage 1,547,805 14,893 (5,027) 1,557,671 1,336,531 3,362 (24,684) 1,315,209 Other mortgage-backed 678,804 7,728 (1,848) 684,684 477,665 520 (11,251) 466,934 Municipal securities 228,632 5,898 (99) 234,431 229,600 461 (2,874) 227,187 Corporate debt securities 112,797 1,791 (487) 114,101 86,074 — (3,725) 82,349 Total securities available-for-sale $ 2,851,479 $ 31,205 $ (9,298) $ 2,873,386 $ 2,311,920 $ 4,405 $ (44,316) $ 2,272,009 Securities Held-to-Maturity Municipal securities $ 21,997 $ — $ (763) $ 21,234 $ 10,176 $ — $ (305) $ 9,871 Equity Securities $ 42,136 $ 30,806
Remaining Contractual Maturity of Securities	Remaining Contractual Maturity of Securities (Dollar amounts in thousands) As of December 31, 2019 Available-for-Sale Held-to-Maturity Amortized Cost Fair Value Amortized Cost Fair Value One year or less $ 131,855 $ 133,155 $ 8,672 $ 8,371 After one year to five years 193,902 195,814 6,037 5,828 After five years to ten years 299,113 302,062 4,417 4,264 After ten years — — 2,871 2,771 Securities that do not have a single contractual maturity date 2,226,609 2,242,355 — — Total $ 2,851,479 $ 2,873,386 $ 21,997 $ 21,234
Changes in OTTI Recognized in Earnings	The following table presents a rollforward of life-to-date OTTI recognized in earnings related to all securities available-for-sale held by the Company for the years ended December 31, 2019, 2018, and 2017. Changes in OTTI Recognized in Earnings (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ — $ — $ 23,345 OTTI included in earnings (1) : Reduction for securities sales (2) — — (23,345) Ending balance $ — $ — $ — (1) Included in net securities losses in the Consolidated Statements of Income. (2) These reductions were driven by the sale of 11 collateralized debt obligations ("CDOs") with a carrying value of $47.7 million during the year ended December 31, 2017.
Securities in an Unrealized Loss Position	The following table presents the aggregate amount of unrealized losses and the aggregate related fair values of securities with unrealized losses as of December 31, 2019 and 2018. Securities in an Unrealized Loss Position (Dollar amounts in thousands) Less Than 12 Months Greater Than 12 Months Total Number of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses As of December 31, 2019 Securities Available-for-Sale U.S. treasury securities 5 $ 4,966 $ 1 $ — $ — $ 4,966 $ 1 U.S. agency securities 52 97,729 1,200 49,387 636 147,116 1,836 CMOs 148 187,470 2,177 412,083 2,850 599,553 5,027 MBSs 59 66,340 996 121,861 852 188,201 1,848 Municipal securities 16 9,384 89 3,104 10 12,488 99 Corporate debt securities 6 9,719 281 21,955 206 31,674 487 Total 286 $ 375,608 $ 4,744 $ 608,390 $ 4,554 $ 983,998 $ 9,298 Securities Held-to-Maturity Municipal securities 30 $ 12,202 $ 439 $ 9,032 $ 324 $ 21,234 $ 763 As of December 31, 2018 Securities Available-for-Sale U.S. treasury securities 17 $ 15,894 $ 57 $ 13,886 $ 118 $ 29,780 $ 175 U.S. agency securities 74 34,263 320 93,227 1,287 127,490 1,607 CMOs 234 171,901 1,671 863,747 23,013 1,035,648 24,684 MBSs 118 135,791 1,715 284,273 9,536 420,064 11,251 Municipal securities 423 60,863 558 109,935 2,316 170,798 2,874 Corporate debt securities 16 82,349 3,725 — — 82,349 3,725 Total 882 $ 501,061 $ 8,046 $ 1,365,068 $ 36,270 $ 1,866,129 $ 44,316 Securities Held-to-Maturity Municipal securities 5 $ — $ — $ 9,871 $ 305 $ 9,871 $ 305

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Composition Of Loan Portfolio	The following table presents the Company's loans held-for-investment by class. Loan Portfolio (Dollar amounts in thousands) As of December 31, 2019 2018 Commercial and industrial $ 4,481,525 $ 4,120,293 Agricultural 405,616 430,928 Commercial real estate: Office, retail, and industrial 1,848,718 1,820,917 Multi-family 856,553 764,185 Construction 593,093 649,337 Other commercial real estate 1,383,708 1,361,810 Total commercial real estate 4,682,072 4,596,249 Total corporate loans 9,569,213 9,147,470 Home equity 851,454 851,607 1-4 family mortgages 1,927,078 1,017,181 Installment 492,585 430,525 Total consumer loans 3,271,117 2,299,313 Total loans $ 12,840,330 $ 11,446,783 Deferred loan fees included in total loans $ 7,972 $ 6,715 Overdrawn demand deposits included in total loans 10,675 8,583
Schedule of Financial Instruments Owned and Pledged as Collateral	The carrying values of loans that were pledged to secure liabilities as of December 31, 2019 and 2018 are presented below. Carrying Value of Loans Pledged (Dollar amounts in thousands) As of December 31 2019 2018 Loans pledged to secure: FHLB advances (blanket pledge) $ 5,371,872 $ 4,443,268 FRB's Discount Window Primary Credit Program 1,173,250 1,166,128 Total $ 6,545,122 $ 5,609,396
Schedule of Loans Sold	The following table presents loan sales for the years ended December 31, 2019, 2018, and 2017. Loan Sales (Dollar amounts in thousands) As of December 31, 2019 2018 2017 Corporate loan sales Proceeds from sales $ 14,650 $ 17,900 $ 52,974 Less book value of loans sold 14,149 17,498 51,781 Net gains on corporate sales (1) 501 402 1,193 1-4 family mortgage loan sales Proceeds from sales 474,384 245,967 258,626 Less book value of loans sold 464,893 240,807 252,741 Net gains on 1-4 family mortgage sales (2) 9,491 5,160 5,885 Total net gains on loan sales $ 9,992 $ 5,562 $ 7,078 (1) Net gains on corporate loan sales are included in other service charges, commissions, and fees in the Consolidated Statements of Income. (2) Net gains on 1-4 family mortgage loan sales are included in mortgage banking income in the Consolidated Statements of Income.

Acquired and Covered Loans (Tab

Acquired and Covered Loans (Tables)	12 Months Ended
	Dec. 31, 2019
Transfers and Servicing [Abstract]
Acquired and Covered Loans	The following table presents acquired and covered PCI and Non-PCI loans as of December 31, 2019 and 2018. Acquired and Covered Loans (Dollar amounts in thousands) As of December 31, 2019 2018 PCI Non-PCI Total PCI Non-PCI Total Acquired loans $ 161,794 $ 1,212,420 $ 1,374,214 $ 108,049 $ 1,247,492 $ 1,355,541 Covered loans 5,389 3,713 9,102 5,819 4,869 10,688 Total acquired and covered loans $ 167,183 $ 1,216,133 $ 1,383,316 $ 113,868 $ 1,252,361 $ 1,366,229
Changes In Accretable Yield For Purchased Credit Impaired Loans	Changes in the accretable yield for acquired and covered PCI loans were as follows. Changes in Accretable Yield (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 43,725 $ 32,957 $ 19,386 Additions 16,037 3,699 27,316 Accretion (20,607) (12,354) (15,529) Other (1) (146) 19,423 1,784 Ending balance $ 39,009 $ 43,725 $ 32,957 (1) Decreases result from the resolution of certain loans occurring earlier than anticipated while increases represent a rise in the expected future cash flows to be collected over the remaining estimated life of the underlying portfolio.

Past Due Loans, Allowance For_2

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs (Tables)	12 Months Ended
	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Past Due Financing Receivables	The following table presents an aging analysis of the Company's past due loans as of December 31, 2019 and 2018. The aging is determined without regard to accrual status. The table also presents non-performing loans, consisting of non-accrual loans (the majority of which are past due) and loans 90 days or more past due and still accruing interest, as of each balance sheet date. Aging Analysis of Past Due Loans and Non-Performing Loans by Class (Dollar amounts in thousands) Aging Analysis (Accruing and Non-accrual) Non-performing Loans Current (1) 30-89 Days Past Due 90 Days or More Past Due Total Past Due Total Loans Non-accrual 90 Days or More Past Due, Still Accruing Interest As of December 31, 2019 Commercial and industrial $ 4,455,381 $ 11,468 $ 14,676 $ 26,144 $ 4,481,525 $ 29,995 $ 2,207 Agricultural 398,676 850 6,090 6,940 405,616 5,954 358 Commercial real estate: Office, retail, and industrial 1,830,321 2,943 15,454 18,397 1,848,718 25,857 546 Multi-family 853,762 211 2,580 2,791 856,553 2,697 — Construction 588,065 4,876 152 5,028 593,093 152 — Other commercial real estate 1,377,678 3,233 2,797 6,030 1,383,708 4,729 529 Total commercial real estate 4,649,826 11,263 20,983 32,246 4,682,072 33,435 1,075 Total corporate loans 9,503,883 23,581 41,749 65,330 9,569,213 69,384 3,640 Home equity 841,908 4,992 4,554 9,546 851,454 8,443 146 1-4 family mortgages 1,917,648 5,452 3,978 9,430 1,927,078 4,442 1,203 Installment 491,406 1,167 12 1,179 492,585 — 12 Total consumer loans 3,250,962 11,611 8,544 20,155 3,271,117 12,885 1,361 Total loans $ 12,754,845 $ 35,192 $ 50,293 $ 85,485 $ 12,840,330 $ 82,269 $ 5,001 As of December 31, 2018 Commercial and industrial $ 4,085,164 $ 8,832 $ 26,297 $ 35,129 $ 4,120,293 $ 33,507 $ 422 Agricultural 428,357 940 1,631 2,571 430,928 1,564 101 Commercial real estate: Office, retail, and industrial 1,803,059 8,209 9,649 17,858 1,820,917 6,510 4,081 Multi-family 759,402 1,487 3,296 4,783 764,185 3,107 189 Construction 645,774 3,419 144 3,563 649,337 144 — Other commercial real estate 1,353,442 4,921 3,447 8,368 1,361,810 2,854 2,197 Total commercial real estate 4,561,677 18,036 16,536 34,572 4,596,249 12,615 6,467 Total corporate loans 9,075,198 27,808 44,464 72,272 9,147,470 47,686 6,990 Home equity 843,217 6,285 2,105 8,390 851,607 5,393 104 1-4 family mortgages 1,009,925 4,361 2,895 7,256 1,017,181 3,856 1,147 Installment 428,836 1,648 41 1,689 430,525 — 41 Total consumer loans 2,281,978 12,294 5,041 17,335 2,299,313 9,249 1,292 Total loans $ 11,357,176 $ 40,102 $ 49,505 $ 89,607 $ 11,446,783 $ 56,935 $ 8,282 (1) PCI loans with an accretable yield are considered current.
Allowance For Credit Losses On Financing Receivables	A rollforward of the allowance for credit losses by portfolio segment for the years ended December 31, 2019, 2018, and 2017 is presented in the table below. Allowance for Credit Losses by Portfolio Segment (Dollar amounts in thousands) Commercial, Industrial, and Agricultural Office, Retail, and Industrial Multi-family Construction Other Commercial Real Estate Consumer Reserve for Unfunded Commitments Total Allowance for Credit Losses Year Ended December 31, 2019 Beginning balance $ 63,276 $ 7,900 $ 2,464 $ 2,173 $ 4,934 $ 21,472 $ 1,200 $ 103,419 Charge-offs (28,008) (2,800) (340) (10) (800) (14,250) — (46,208) Recoveries 4,815 253 478 19 357 2,062 — 7,984 Net charge-offs (23,193) (2,547) 138 9 (443) (12,188) — (38,224) Provision for loan 22,747 2,227 348 (485) 1,917 17,273 — 44,027 Ending Balance $ 62,830 $ 7,580 $ 2,950 $ 1,697 $ 6,408 $ 26,557 $ 1,200 $ 109,222 Year Ended December 31, 2018 Beginning balance $ 55,791 $ 10,996 $ 2,534 $ 3,481 $ 6,381 $ 16,546 $ 1,000 $ 96,729 Charge-offs (36,477) (2,286) (5) (1) (410) (8,806) — (47,985) Recoveries 2,946 334 3 125 1,532 1,681 — 6,621 Net charge-offs (33,531) (1,952) (2) 124 1,122 (7,125) — (41,364) Provision for loan losses and other 41,016 (1,144) (68) (1,432) (2,569) 12,051 200 48,054 Ending balance $ 63,276 $ 7,900 $ 2,464 $ 2,173 $ 4,934 $ 21,472 $ 1,200 $ 103,419 Year Ended December 31, 2017 Beginning balance $ 40,709 $ 17,595 $ 3,261 $ 3,444 $ 7,739 $ 13,335 $ 1,000 $ 87,083 Charge-offs (22,885) (190) — (38) (755) (6,955) — (30,823) Recoveries 4,150 2,935 39 270 244 1,541 — 9,179 Net charge-offs (18,735) 2,745 39 232 (511) (5,414) — (21,644) Provision for loan 33,817 (9,344) (766) (195) (847) 8,625 — 31,290 Ending balance $ 55,791 $ 10,996 $ 2,534 $ 3,481 $ 6,381 $ 16,546 $ 1,000 $ 96,729
Schedule of Loans and The Related Allowance for Credit Losses	The table below provides a breakdown of loans and the related allowance for credit losses by portfolio segment as of December 31, 2019 and 2018. Loans and Related Allowance for Credit Losses by Portfolio Segment (Dollar amounts in thousands) Loans Allowance for Credit Losses Individually Evaluated for Impairment Collectively Evaluated for Impairment PCI Total Individually Evaluated for Impairment Collectively Evaluated for Impairment PCI Total As of December 31, 2019 Commercial, industrial, and $ 34,142 $ 4,807,114 $ 45,885 $ 4,887,141 $ 3,414 $ 59,108 $ 308 $ 62,830 Commercial real estate: Office, retail, and industrial 24,820 1,795,557 28,341 1,848,718 578 6,899 103 7,580 Multi-family 1,995 851,857 2,701 856,553 — 2,854 96 2,950 Construction 123 581,747 11,223 593,093 — 1,681 16 1,697 Other commercial real estate 3,241 1,323,635 56,832 1,383,708 — 4,867 1,541 6,408 Total commercial real estate 30,179 4,552,796 99,097 4,682,072 578 16,301 1,756 18,635 Total corporate loans 64,321 9,359,910 144,982 9,569,213 3,992 75,409 2,064 81,465 Consumer — 3,248,916 22,201 3,271,117 — 25,424 1,133 26,557 Reserve for unfunded — — — — — 1,200 — 1,200 Total loans $ 64,321 $ 12,608,826 $ 167,183 $ 12,840,330 $ 3,992 $ 102,033 $ 3,197 $ 109,222 As of December 31, 2018 Commercial, industrial, and $ 32,415 $ 4,514,349 $ 4,457 $ 4,551,221 $ 3,961 $ 58,947 $ 368 $ 63,276 Commercial real estate: Office, retail, and industrial 5,057 1,799,304 16,556 1,820,917 748 5,984 1,168 7,900 Multi-family 3,492 747,030 13,663 764,185 — 2,154 310 2,464 Construction — 644,499 4,838 649,337 — 2,019 154 2,173 Other commercial real estate 1,545 1,305,444 54,821 1,361,810 — 4,180 754 4,934 Total commercial real estate 10,094 4,496,277 89,878 4,596,249 748 14,337 2,386 17,471 Total corporate loans 42,509 9,010,626 94,335 9,147,470 4,709 73,284 2,754 80,747 Consumer — 2,279,780 19,533 2,299,313 — 20,094 1,378 21,472 Reserve for unfunded — — — — — 1,200 — 1,200 Total loans $ 42,509 $ 11,290,406 $ 113,868 $ 11,446,783 $ 4,709 $ 94,578 $ 4,132 $ 103,419
Impaired Financing Receivables	The following table presents loans individually evaluated for impairment by class of loan as of December 31, 2019 and 2018. PCI loans are excluded from this disclosure. Impaired Loans Individually Evaluated by Class (Dollar amounts in thousands) As of December 31, 2019 2018 Recorded Investment In Recorded Investment In Loans with No Specific Reserve Loans with a Specific Reserve Unpaid Principal Balance Specific Reserve Loans with No Specific Reserve Loans with a Specific Reserve Unpaid Principal Balance Specific Reserve Commercial and industrial $ 12,885 $ 15,516 $ 52,559 $ 2,456 $ 7,550 $ 23,349 $ 49,102 $ 3,960 Agricultural 1,889 3,852 9,293 958 1,318 198 3,997 1 Commercial real estate: Office, retail, and industrial 14,111 10,709 37,007 578 1,861 3,196 6,141 748 Multi-family 1,995 — 1,995 — 3,492 — 3,492 — Construction 123 — 123 — — — — — Other commercial real estate 3,241 — 3,495 — 1,545 — 1,612 — Total commercial real estate 19,470 10,709 42,620 578 6,898 3,196 11,245 748 Total impaired loans $ 34,244 $ 30,077 $ 104,472 $ 3,992 $ 15,766 $ 26,743 $ 64,344 $ 4,709 The following table presents the average recorded investment and interest income recognized on impaired loans by class for the years ended December 31, 2019, 2018, and 2017. PCI loans are excluded from this disclosure. Average Recorded Investment and Interest Income Recognized on Impaired Loans by Class (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Average Recorded Investment Interest Income Recognized (1) Average Recorded Investment Interest Income Recognized (1) Average Interest Income Recognized (1) Commercial and industrial $ 26,700 $ 115 $ 33,732 $ 225 $ 33,956 $ 1,059 Agricultural 4,374 20 2,026 32 279 101 Commercial real estate: Office, retail, and industrial 17,453 73 8,105 892 13,106 325 Multi-family 3,164 112 2,404 66 441 28 Construction 74 3 — — 7 136 Other commercial real estate 2,662 90 2,179 406 1,615 41 Total commercial real estate 23,352 278 12,688 1,364 15,169 530 Total impaired loans $ 54,427 $ 413 $ 48,445 $ 1,621 $ 49,404 $ 1,690 (1) Recorded using the cash basis of accounting.
Financing Receivable Credit Quality Indicators	The following tables present credit quality indicators by class for corporate and consumer loans as of December 31, 2019 and 2018. Corporate Credit Quality Indicators by Class (Dollar amounts in thousands) Pass Special Mention (1) Substandard (2) Non-accrual (3) Total As of December 31, 2019 Commercial and industrial $ 4,324,709 $ 47,665 $ 79,156 $ 29,995 $ 4,481,525 Agricultural 350,827 32,764 16,071 5,954 405,616 Commercial real estate: Office, retail, and industrial 1,747,287 42,230 33,344 25,857 1,848,718 Multi-family 839,615 8,279 5,962 2,697 856,553 Construction 564,495 17,977 10,469 152 593,093 Other commercial real estate 1,295,155 39,788 44,036 4,729 1,383,708 Total commercial real estate 4,446,552 108,274 93,811 33,435 4,682,072 Total corporate loans $ 9,122,088 $ 188,703 $ 189,038 $ 69,384 $ 9,569,213 As of December 31, 2018 Commercial and industrial $ 3,952,066 $ 74,878 $ 59,842 $ 33,507 $ 4,120,293 Agricultural 407,542 10,070 11,752 1,564 430,928 Commercial real estate: Office, retail, and industrial 1,735,426 35,853 43,128 6,510 1,820,917 Multi-family 745,131 9,273 6,674 3,107 764,185 Construction 624,446 16,370 8,377 144 649,337 Other commercial real estate 1,294,128 47,736 17,092 2,854 1,361,810 Total commercial real estate 4,399,131 109,232 75,271 12,615 4,596,249 Total corporate loans $ 8,758,739 $ 194,180 $ 146,865 $ 47,686 $ 9,147,470 (1) Loans categorized as special mention exhibit potential weaknesses that require the close attention of management since these potential weaknesses may result in the deterioration of repayment prospects in the future. (2) Loans categorized as substandard exhibit a well-defined weakness that may jeopardize the liquidation of the debt. These loans continue to accrue interest because they are well-secured and collection of principal and interest is expected within a reasonable time. (3) Loans categorized as non-accrual exhibit a well-defined weakness that may jeopardize the liquidation of the debt or result in a loss if the deficiencies are not corrected. Consumer Credit Quality Indicators by Class (Dollar amounts in thousands) Performing Non-accrual Total As of December 31, 2019 Home equity $ 843,011 $ 8,443 $ 851,454 1-4 family mortgages 1,922,636 4,442 1,927,078 Installment 492,585 — 492,585 Total consumer loans $ 3,258,232 $ 12,885 $ 3,271,117 As of December 31, 2018 Home equity $ 846,214 $ 5,393 $ 851,607 1-4 family mortgages 1,013,325 3,856 1,017,181 Installment 430,525 — 430,525 Total consumer loans $ 2,290,064 $ 9,249 $ 2,299,313
Troubled Debt Restructurings on Financing Receivables	The table below presents TDRs by class as of December 31, 2019 and 2018. See Note 1, "Summary of Significant Accounting Policies," for the accounting policy for TDRs. TDRs by Class (Dollar amounts in thousands) As of December 31, 2019 2018 Accruing Non-accrual (1) Total Accruing Non-accrual (1) Total Commercial and industrial $ 227 $ 16,420 $ 16,647 $ 246 $ 5,994 $ 6,240 Agricultural — — — — — — Commercial real estate: Office, retail, and industrial — 3,600 3,600 — — — Multi-family 163 — 163 557 — 557 Construction — — — — — — Other commercial real estate 170 — 170 181 — 181 Total commercial real estate 333 3,600 3,933 738 — 738 Total corporate loans 560 20,020 20,580 984 5,994 6,978 Home equity 36 240 276 113 327 440 1-4 family mortgages 637 — 637 769 291 1,060 Installment — 254 254 — — — Total consumer loans 673 494 1,167 882 618 1,500 Total loans $ 1,233 $ 20,514 $ 21,747 $ 1,866 $ 6,612 $ 8,478 (1) These TDRs are included in non-accrual loans in the preceding tables. Loans Restructured During the Period (Dollar amounts in thousands) Number of Loans Pre-Modification Recorded Investment Funds Disbursed Interest and Escrow Capitalized Charge-offs Post-Modification Recorded Investment Year Ended December 31, 2019 Commercial and industrial 5 $ 13,616 $ — $ — $ 1,424 $ 12,192 Office, retail, and industrial 2 4,473 — — 873 3,600 Multi-family 1 12 — — — 12 Total loans restructured during the period 8 $ 18,101 $ — $ — $ 2,297 $ 15,804 Year Ended December 31, 2017 Commercial and industrial 12 $ 26,733 $ 9,035 $ — $ 6,232 $ 29,536 Office, retail, and industrial 2 3,656 — — — 3,656 Total loans restructured during the period 14 $ 30,389 $ 9,035 $ — $ 6,232 $ 33,192 A rollforward of the carrying value of TDRs for the years ended December 31, 2019, 2018, and 2017 is presented in the following table. TDR Rollforward (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Accruing Beginning balance $ 1,866 $ 1,796 $ 2,291 Additions 12 — 15,819 Net payments (262) (50) (1,923) Returned to performing status — — — Net transfers (to) from non-accrual (383) 120 (14,391) Ending balance 1,233 1,866 1,796 Non-accrual Beginning balance 6,612 24,533 6,297 Additions 18,089 527 14,570 Net payments (1,013) (14,403) (4,380) Charge-offs (3,557) (3,925) (6,345) Transfers to OREO — — — Loans sold — — — Net transfers from (to) accruing 383 (120) 14,391 Ending balance 20,514 6,612 24,533 Total TDRs $ 21,747 $ 8,478 $ 26,329

Premises, Furniture, and Equi_2

Premises, Furniture, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	The following table summarizes the Company's premises, furniture, and equipment by category. Premises, Furniture, and Equipment (Dollar amounts in thousands) As of December 31, 2019 2018 Land $ 30,807 $ 28,187 Premises 132,427 122,003 Furniture and equipment 137,349 127,421 Total cost 300,583 277,611 Accumulated depreciation (159,411) (148,831) Net book value of premises, furniture, and equipment 141,172 128,780 Assets held-for-sale 6,824 3,722 Premises, furniture, and equipment, net $ 147,996 $ 132,502

Lease Obligations (Tables)

Lease Obligations (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of Future Minimum Lease Liability	The following summary reflects the future minimum payments by year required under operating leases that have initial or remaining non-cancelable lease terms in excess of one year and a reconciliation of those payments to the Company's lease liability as of December 31, 2019. Lease Liability (Dollar amounts in thousands) Total Year Ending December 31, 2020 $ 17,855 2021 17,873 2022 18,007 2023 18,175 2024 18,090 2025 and thereafter 103,967 Total minimum lease payments 193,967 Discount (1) (32,403) Lease liability (2) $ 161,564 (1) Represents the net present value adjustment related to minimum lease payments. (2) Included in accrued interest payable and other liabilities in the Consolidated Statements of Financial Condition.
Schedule of Net Operating Lease Expense	The following table presents net operating lease expense for the years ended December 31, 2019, 2018, and 2017. Net Operating Lease Expense (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Lease expense charged to operations $ 17,681 $ 24,880 $ 18,666 Accretion of operating lease intangible (1) (162) (972) (1,180) Accretion of deferred gain on sale-leaseback transaction (1) — (9,126) (5,872) Rental income from premises leased to others (1) (720) (510) (682) Net operating lease expense $ 16,799 $ 14,272 $ 10,932 (1) Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table presents changes in the carrying amount of goodwill for the years ended December 31, 2019, 2018, and 2017. Changes in the Carrying Amount of Goodwill (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 728,809 $ 697,608 $ 340,879 Acquisitions 67,947 31,201 356,729 Ending balance $ 796,756 $ 728,809 $ 697,608
Schedule of Finite-Lived Intangible Assets	Other Intangible Assets (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Gross Accumulated Amortization Net Gross Accumulated Amortization Net Gross Accumulated Amortization Net Beginning balance $ 110,206 $ 48,271 $ 61,935 $ 97,976 $ 40,827 $ 57,149 $ 58,959 $ 32,962 $ 25,997 Additions 27,052 — 27,052 12,230 — 12,230 39,017 — 39,017 Amortization expense — 10,481 (10,481) — 7,444 (7,444) — 7,865 (7,865) Ending balance $ 137,258 $ 58,752 $ 78,506 $ 110,206 $ 48,271 $ 61,935 $ 97,976 $ 40,827 $ 57,149 Weighted-average remaining life (in years) 7.5 7.8 8.3 Estimated remaining useful lives (in years) 0.5 to 9.3 0.7 to 9.8 0.2 to 9.3
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Scheduled Amortization of Other Intangible Assets (Dollar amounts in thousands) Total Year Ending December 31, 2020 $ 10,951 2021 10,875 2022 10,796 2023 10,418 2024 10,172 2025 and thereafter 25,294 Total $ 78,506

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Schedule of Deposits	The following table presents the Company's deposits by type. Summary of Deposits (Dollar amounts in thousands) As of December 31, 2019 2018 Demand deposits $ 3,802,422 $ 3,642,989 Savings deposits 2,062,848 2,053,494 NOW accounts 2,259,505 2,063,213 Money market deposits 2,093,049 1,783,512 Time deposits less than $100,000 1,615,609 1,348,664 Time deposits greater than $100,000 1,417,845 1,192,240 Total deposits $ 13,251,278 $ 12,084,112
Schedule of Maturities of Time Deposits	The following table provides maturity information related to the Company's time deposits. Scheduled Maturities of Time Deposits (Dollar amounts in thousands) Total Year Ending December 31, 2020 $ 2,800,474 2021 150,806 2022 34,140 2023 17,894 2024 29,792 2025 and thereafter 348 Total $ 3,033,454

Borrowed Funds (Tables)

Borrowed Funds (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Debt	The following table summarizes the Company's borrowed funds by funding source. Summary of Borrowed Funds (Dollar amounts in thousands) As of December 31, 2019 2018 Securities sold under agreements to repurchase $ 103,515 $ 121,079 Federal funds purchased 160,000 — FHLB advances 1,395,243 785,000 Total borrowed funds $ 1,658,758 $ 906,079
Unused Short-Term Credit Lines Available for Use	The following table presents short-term credit lines available for use, for which the Company did not have an outstanding balance as of December 31, 2019 and 2018. Short-Term Credit Lines Available for Use (Dollar amounts in thousands) As of December 31, 2019 2018 FRB's Discount Window Primary Credit Program $ 874,256 $ 881,113 Available federal funds lines 718,000 684,000 Correspondent bank line of credit 50,000 50,000

Senior and Subordinated Debt (T

Senior and Subordinated Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table presents the Company's senior and subordinated debt by issuance. Senior and Subordinated Debt (Dollar amounts in thousands) As of December 31, Issuance Date Maturity Date Interest Rate 2019 2018 Subordinated notes September 2016 September 2026 5.875% $ 147,637 $ 147,282 Junior subordinated debentures: First Midwest Capital Trust I ("FMCT") November 2003 December 2033 6.950% 37,805 37,803 Great Lakes Statutory Trust II ("GLST II") (1) December 2005 December 2035 L+1.400% (2) 4,674 4,580 Great Lakes Statutory Trust III ("GLST III") (1) June 2007 September 2037 L+1.700% (2) 6,187 6,071 Northern States Statutory Trust I ("NSST I") (1) September 2005 September 2035 L+1.800% (2) 8,206 8,072 Bridgeview Statutory Trust I ("BST") (1) July 2001 July 2031 L+3.580% (2) 14,542 — Bridgeview Capital Trust II ("BCT") (1) December 2002 January 2033 L+3.350% (2) 14,897 — Total junior subordinated debentures 86,311 56,526 Total senior and subordinated debt $ 233,948 $ 203,808 (1) The junior subordinated debentures related to BST, BCT, GLST II, GLST III, and NSST I were assumed by the Company through acquisitions. These amounts include acquisition adjustment discounts that total $7.2 million and $6.0 million as of December 31, 2019 and 2018, respectively. (2) The interest rates are variable rates based on three-month LIBOR plus the margin indicated.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The table below displays the calculation of basic and diluted EPS. Basic and Diluted EPS (Amounts in thousands, except per share data) Years Ended December 31, 2019 2018 2017 Net income $ 199,738 $ 157,870 $ 98,387 Net income applicable to non-vested restricted shares (1,681) (1,312) (916) Net income applicable to common shares $ 198,057 $ 156,558 $ 97,471 Weighted-average common shares outstanding: Weighted-average common shares outstanding (basic) 108,156 102,850 101,423 Dilutive effect of common stock equivalents 428 4 20 Weighted-average diluted common shares outstanding 108,584 102,854 101,443 Basic EPS $ 1.83 $ 1.52 $ 0.96 Diluted EPS 1.82 1.52 0.96 Anti-dilutive shares not included in the computation of diluted EPS (1) — 27 229 (1) This amount represents outstanding stock options for which the exercise price is greater than the average market price of the Company's common stock. The final outstanding stock options were exercised during the first quarter of 2018.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Components of Income Tax Expense (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Current income tax expense (benefit): Federal $ 50,141 $ 13,497 $ 93,540 State 5,116 (619) 104 Total 55,257 12,878 93,644 Deferred income tax expense (benefit): Federal (1,879) 14,489 (12,219) State 12,823 11,820 8,142 Total 10,944 26,309 (4,077) Total income tax expense $ 66,201 $ 39,187 $ 89,567
Schedule of Effective Income Tax Rate Reconciliation	Components of Effective Tax Rate (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Amount % of Pretax Income Amount % of Pretax Income Amount % of Pretax Income Statutory federal income tax $ 55,847 21.0 $ 41,382 21.0 $ 65,784 35.0 Increase (decrease) in income taxes resulting from: State income tax, net of federal income tax effect 14,172 5.3 8,846 4.5 5,069 2.7 Tax-exempt income, net of interest expense disallowance (3,234) (1.2) (3,104) (1.6) (5,065) (2.7) Deferred tax asset revaluation — — (8,721) (4.4) 23,709 12.6 Other (584) (0.2) 784 0.4 70 0.1 Total $ 66,201 24.9 % $ 39,187 19.9 % $ 89,567 47.7 %
Schedule of Deferred Tax Assets and Liabilities	Deferred Tax Assets and Liabilities (Dollar amounts in thousands) As of December 31, 2019 2018 Deferred tax assets: Lease liability 33,871 $ — Allowance for credit losses 21,010 19,591 Federal net operating loss ("NOL") carryforwards 19,505 8,871 Non-equity based compensation 7,115 2,210 Equity based compensation 5,043 3,971 OREO 1,996 1,460 Alternative minimum tax ("AMT") and other credit carryforwards 368 244 Deferred gain on sale-leaseback transaction — 13,752 State NOL carryforwards — 6,240 Deferred incentives — 1,382 Property valuation adjustments — 1,214 Other 6,988 5,232 Total deferred tax assets 95,896 64,167 Deferred tax liabilities: Right-of-use asset (29,611) — Accrued retirement benefits (8,453) (8,502) Fixed assets (5,648) (7,322) Deferred loan fees and costs (5,445) (4,985) Acquisition adjustments (1,261) (686) Other (2,821) (2,823) Total deferred tax liabilities (53,239) (24,318) Deferred tax valuation allowance — — Net deferred tax assets 42,657 39,849 Tax effect of adjustments related to other comprehensive income (loss) 725 20,280 Net deferred tax assets including adjustments $ 43,382 $ 60,129 NOL carryforwards available to offset future taxable income: Federal gross NOL carryforwards, begin to expire in 2030 $ 92,880 $ 42,242 Illinois gross NOL carryforwards — 209,802 Indiana gross NOL carryforwards — 14,260 Wisconsin gross NOL carryforwards — 1,212 AMT credits 204 —
Summary of Income Tax Contingencies	Rollforward of Unrecognized Tax Benefits (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 16,350 $ 16,248 $ 2,039 Additions for tax positions relating to the current year 1,158 1,209 845 Additions for tax positions relating to prior years — 582 13,389 Reductions for tax positions relating to prior years (224) (60) (25) Reductions for settlements with taxing authorities (900) (1,629) — Ending balance $ 16,384 $ 16,350 $ 16,248 Interest and penalties not included above (1) : Interest expense (income) , net of tax effect, and penalties $ 38 $ (21) $ 118 Accrued interest and penalties, net of tax effect, at end of year 208 170 191 (1) Included in income tax expense in the Consolidated Statements of Income.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Profit Sharing Plan	Profit Sharing Plan (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Profit sharing expense (1) $ 8,226 $ 7,803 $ 7,346 Company dividends received by the Profit Sharing Plan $ 414 $ 457 $ 441 Company shares held by the Profit Sharing Plan at the end of the year: Number of shares 812,886 1,047,213 1,079,975 Fair value $ 18,745 $ 20,745 $ 25,930 (1) Included in retirement and other employee benefits in the Consolidated Statements of Income.
Schedule of Pension Plan Cost and Obligation	Pension Plan Cost and Obligations (Dollar amounts in thousands) As of December 31, 2019 2018 Accumulated benefit obligation $ 70,236 $ 58,271 Change in projected benefit obligation Beginning balance $ 58,271 $ 67,923 Service cost — — Interest cost 1,841 2,031 Settlements (4,268) (7,199) Actuarial loss (gain) 15,200 (3,717) Benefits paid (808) (767) Ending balance $ 70,236 $ 58,271 Change in fair value of plan assets Beginning balance $ 76,210 $ 66,159 Actual return on plan assets 21,156 (6,983) Benefits paid (808) (767) Employer contributions — 25,000 Settlements (4,268) (7,199) Ending balance $ 92,290 $ 76,210 Funded status recognized in the Consolidated Statements of Financial Condition Noncurrent asset $ 22,054 $ 17,939 Amounts recognized in accumulated other comprehensive loss Prior service cost $ — $ — Net loss 25,721 29,345 Net amount recognized $ 25,721 $ 29,345 Actuarial losses included in accumulated other comprehensive loss as a percent of Accumulated benefit obligation 36.6 % 50.4 % Fair value of plan assets 27.9 % 38.5 % Amounts expected to be amortized from accumulated other comprehensive loss into net periodic benefit cost in the next fiscal year Prior service cost $ — $ — Net loss 820 426 Net amount expected to be recognized $ 820 $ 426 Weighted-average assumptions at the end of the year used to determine the actuarial present value of the projected benefit obligation Discount rate 3.04 % 4.10 %
Schedule of Net Periodic Benefit Pension Costs	Net Periodic Benefit Pension Cost (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Components of net periodic benefit cost Interest cost $ 1,841 $ 2,031 $ 1,712 Expected return on plan assets (4,642) (3,820) (3,802) Recognized net actuarial loss 531 533 591 Amortization of prior service cost — — — Recognized settlement loss 1,781 2,703 2,480 Net periodic (income) cost (489) 1,447 981 Other changes in plan assets and benefit obligations recognized as Net gain (loss) for the period 1,313 (7,086) (83) Amortization of net loss 2,311 3,236 3,071 Total unrealized gain (loss) 3,624 (3,850) 2,988 Total recognized in net periodic pension cost and other $ 4,113 $ (5,297) $ 2,007 Weighted-average assumptions used to determine the net periodic cost Discount rate 4.10 % 3.45 % 3.86 % Expected return on plan assets 5.75 % 5.75 % 6.25 %
Schedule of Pension Plan Asset Allocation	Pension Plan Asset Allocation (Dollar amounts in thousands) Percentage of Plan Assets as of December 31, Target Allocation Fair Value of Plan Assets (1) 2019 2018 Asset Category Equity securities 50 - 65% $ 54,800 59 % 61 % Fixed income 25 - 55% 33,976 37 % 37 % Cash equivalents 0 - 10% 3,514 4 % 2 % Total $ 92,290 100 % 100 % (1) Additional information regarding the fair value of Pension Plan assets as of December 31, 2019 can be found in Note 22, "Fair Value."
Schedule of Estimated Future Pension Benefit Payments	The following table presents estimated future pension benefit payments under the Pension Plan for retirees already receiving benefits and future retirees, assuming they retire and begin receiving unreduced benefits as soon as they are eligible. Estimated Future Pension Benefit Payments (Dollar amounts in thousands) Year ending December 31, 2020 $ 8,478 2021 5,300 2022 5,872 2023 4,497 2024 4,977 2025-2028 20,844

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Shares of Common Stock Available Under Share-Based Plans	Shares of Common Stock Available Under Share-Based Plans As of December 31, 2019 Shares Authorized Shares Available For Grant 2018 Stock and Incentive Plan (1) 3,295,590 2,648,229 Directors Plan 481,250 102,989
Restricted Stock, Restricted Stock Unit, and Performance Share Award Transactions	Restricted Stock, Restricted Stock Unit, and Performance Share Award Transactions (Amounts in thousands, except per share data) Year Ended December 31, 2019 Restricted Stock/Unit Awards Performance Shares Number of Shares/Units Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Non-vested awards beginning balance 947 $ 23.32 468 $ 19.88 Granted 497 23.04 146 23.04 Vested (417) 21.13 (94) 21.13 Forfeited (35) 24.20 (19) 24.20 Non-vested awards ending balance 992 $ 24.03 501 $ 20.40
Schedule of Other Share-based Compensation, Activity	Other Restricted Stock, Restricted Stock Unit, and Performance Share Award Information (Amounts in thousands, except per share data) Years Ended December 31, 2019 2018 2017 Weighted-average grant date fair value of restricted stock, restricted stock unit, and performance share awards granted during the year $ 23.04 $ 24.96 $ 24.71 Total fair value of restricted stock, restricted stock unit, and performance share awards vested during the year 13,092 10,870 13,760 Income tax benefit realized from the vesting/release of restricted stock, restricted stock unit, and performance share awards 2,920 2,970 4,007
Effect of Recording Share-Based Compensation Expense	Effect of Recording Share-Based Compensation Expense (Dollar amounts in thousands) Years ended December 31, 2019 2018 2017 Total share-based compensation expense (1) $ 13,183 $ 12,062 $ 11,223 Income tax benefit 3,678 3,365 4,601 Share-based compensation expense, net of tax $ 9,505 $ 8,697 $ 6,622 Unrecognized compensation expense $ 14,299 $ 13,982 $ 13,266 Weighted-average amortization period remaining (in years) 1.1 1.2 1.3 (1) Comprised of restricted stock, restricted stock unit, and performance share awards expense.

Regulatory and Capital Matters

Regulatory and Capital Matters (Tables)	12 Months Ended
	Dec. 31, 2019
Banking and Thrift [Abstract]
Summary of Regulatory Capital Ratios	The following table outlines the Company's and the Bank's measures of capital as of the dates presented and the capital guidelines established by the Federal Reserve for the Company and the Bank to be categorized as adequately capitalized and avoid limitations on certain distributions, as well as for the Bank to be categorized as "well-capitalized." Summary of Regulatory Capital Ratios (Dollar amounts in thousands) Actual Adequately Capitalized To Be Well-Capitalized Under Prompt Corrective Action Provisions Capital Ratio % Capital Ratio % Capital Ratio % As of December 31, 2019 Total capital to risk-weighted assets: First Midwest Bancorp, Inc. $ 1,843,597 12.96 $ 1,493,672 10.500 N/A N/A First Midwest Bank 1,598,886 11.28 1,488,796 10.500 $ 1,417,901 10.00 Tier 1 capital to risk-weighted assets: First Midwest Bancorp, Inc. 1,496,048 10.52 1,209,163 8.500 N/A N/A First Midwest Bank 1,489,664 10.51 1,205,215 8.500 1,134,320 8.00 CET1 to risk-weighted assets: First Midwest Bancorp, Inc. 1,496,048 10.52 995,781 7.000 N/A N/A First Midwest Bank 1,489,664 10.51 992,530 7.000 921,635 6.50 Tier 1 capital to average assets: First Midwest Bancorp, Inc. 1,496,048 8.81 679,365 4.000 N/A N/A First Midwest Bank 1,489,664 8.79 677,570 4.000 846,963 5.00 As of December 31, 2018 Total capital to risk-weighted assets: First Midwest Bancorp, Inc. $ 1,626,489 12.62 $ 1,273,103 9.875 N/A N/A First Midwest Bank 1,463,026 11.39 1,268,662 9.875 $ 1,284,721 10.00 Tier 1 capital to risk-weighted assets: First Midwest Bancorp, Inc. 1,315,098 10.20 1,015,259 7.875 N/A N/A First Midwest Bank 1,359,607 10.58 1,011,718 7.875 1,027,777 8.00 CET1 to risk-weighted assets: First Midwest Bancorp, Inc. 1,315,432 10.20 821,876 6.375 N/A N/A First Midwest Bank 1,359,607 10.58 819,009 6.375 835,068 6.50 Tier 1 capital to average assets: First Midwest Bancorp, Inc. 1,315,098 8.90 591,293 4.000 N/A N/A First Midwest Bank 1,359,607 9.41 577,991 4.000 722,488 5.00 N/A – Not applicable.

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Interest Rate Derivatives	Cash Flow Hedges (Dollar amounts in thousands) As of December 31, 2019 2018 Gross notional amount outstanding $ 1,905,000 $ 2,280,000 Derivative asset fair value in other assets (1) 727 6,889 Derivative liability fair value in other liabilities (1) (119) (11,328) Weighted-average interest rate received 1.88 % 2.12 % Weighted-average interest rate paid 1.74 % 2.20 % Weighted-average maturity (in years) 1.18 1.53 (1) Certain cash flow hedges are transacted through a clearinghouse ("centrally cleared") and their change in fair value is settled by the counterparties to the transaction, which results in no fair value. The following table presents the impact of derivative instruments on net interest income for the years ended December 31, 2019, 2018, and 2017. Hedge Income (Dollar amounts in thousands) Years Ended December 30, 2019 2018 2017 Cash Flow Hedges Interest rate swaps in interest income 3,975 2,611 5,159 Interest rate swaps in interest expense (5,008) (3,673) (3,951) Total cash flow hedges (1,033) (1,062) 1,208
Schedule of Derivative Instruments	Other Derivative Instruments (Dollar amounts in thousands) As of December 31, 2019 2018 Gross notional amount outstanding $ 4,340,384 $ 3,085,226 Derivative asset fair value in other assets (1) 61,709 25,168 Derivative liability fair value in other liabilities (1) (18,416) (17,533) Fair value of derivative (2) 18,856 18,013 (1) Certain other derivative instruments are centrally cleared and their change in fair value is settled by the counterparties to the transaction, which results in no fair value. (2) This amount represents the fair value if credit risk related contingent factors were triggered.
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table presents the impact of derivative instruments on comprehensive income and the reclassification of gains (losses) from accumulated other comprehensive loss to net interest income for the years ended December 31, 2019 and 2018, and 2017. Cash Flow Hedge Accounting on Accumulated Other Comprehensive Income (Dollar amounts in thousands) Years Ended December 30, 2019 2018 2017 Gains (losses) recognized in other comprehensive income Interest rate swaps in interest income $ 13,236 $ 18,776 $ 11,150 Interest rate swaps in interest expense (16,873) (20,500) (8,025) Reclassification of gains (losses) included in net income Interest rate swaps in interest income $ 3,975 $ 2,611 $ 5,159 Interest rate swaps in interest expense (5,008) (3,673) (3,951)
Offsetting Assets	The following table presents the fair value of the Company's derivatives and offsetting positions as of December 31, 2019 and 2018. Fair Value of Offsetting Derivatives (Dollar amounts in thousands) As of December 31, 2019 2018 Assets Liabilities Assets Liabilities Gross amounts recognized $ 62,436 $ 18,535 $ 32,057 $ 28,861 Less: amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition (1) 62,436 18,535 32,057 28,861 Gross amounts not offset in the Consolidated Statements of Financial Condition: Offsetting derivative positions (2,674) (2,674) (11,678) (11,678) Cash collateral pledged — (15,861) (9,060) (3,506) Net credit exposure $ 59,762 $ — $ 11,319 $ 13,677 (1) Included in other assets or other liabilities in the Consolidated Statements of Financial Condition.
Offsetting Liabilities	The following table presents the fair value of the Company's derivatives and offsetting positions as of December 31, 2019 and 2018. Fair Value of Offsetting Derivatives (Dollar amounts in thousands) As of December 31, 2019 2018 Assets Liabilities Assets Liabilities Gross amounts recognized $ 62,436 $ 18,535 $ 32,057 $ 28,861 Less: amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition (1) 62,436 18,535 32,057 28,861 Gross amounts not offset in the Consolidated Statements of Financial Condition: Offsetting derivative positions (2,674) (2,674) (11,678) (11,678) Cash collateral pledged — (15,861) (9,060) (3,506) Net credit exposure $ 59,762 $ — $ 11,319 $ 13,677 (1) Included in other assets or other liabilities in the Consolidated Statements of Financial Condition.

Commitments, Guarantees, and _2

Commitments, Guarantees, and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments Disclosure	Contractual or Notional Amounts of Financial Instruments (Dollar amounts in thousands) As of December 31, 2019 2018 Commitments to extend credit: Commercial, industrial, and agricultural $ 1,852,040 $ 1,729,286 Commercial real estate 296,053 296,882 Home equity 576,956 570,553 Other commitments (1) 251,093 244,917 Total commitments to extend credit $ 2,976,142 $ 2,841,638 Letters of credit $ 103,684 $ 112,728 (1) Other commitments includes installment and overdraft protection program commitments.

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table provides the fair value for assets and liabilities required to be measured at fair value on a recurring basis in the Consolidated Statements of Financial Condition by level in the fair value hierarchy. Recurring Fair Value Measurements (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets Equity securities $ 23,703 $ 13,400 $ — $ 19,658 $ 11,148 $ — Securities available-for-sale U.S. treasury securities 34,075 — — 37,767 — — U.S. agency securities — 248,424 — — 142,563 — CMOs — 1,557,671 — — 1,315,209 — MBSs — 684,684 — — 466,934 — Municipal securities — 234,431 — — 227,187 — Corporate debt securities — 114,101 — — 82,349 — Total securities available-for-sale 34,075 2,839,311 — 37,767 2,234,242 — Mortgage servicing rights ("MSRs") (1) — — 5,858 — — 6,730 Derivative assets (1) — 62,436 — — 32,057 — Liabilities Derivative liabilities (2) $ — $ 18,535 $ — $ — $ 28,861 $ — (1) Included in other assets in the Consolidated Statements of Financial Condition. (2) Included in other liabilities in the Consolidated Statements of Financial Condition.
Carrying Value of CDOs	A rollforward of the carrying value of CDOs for the year ended December 31, 2017 is presented in the following table. Carrying Value of CDOs (Dollar amounts in thousands) Years Ended December 31, 2017 Beginning balance $ 33,260 Additions — Change in other comprehensive income (1) 14,421 Paydowns and sales (47,681) Ending balance $ — (1) Included in unrealized holding gains (losses) in the Consolidated Statements of Comprehensive Income.
Significant Unobservable Inputs Used in the Valuation of MSRs	The following table presents the ranges of significant, unobservable inputs used by the Company to determine the fair value of MSRs as of December 31, 2019 and 2018. Significant Unobservable Inputs Used in the Valuation of MSRs As of December 31, 2019 2018 Prepayment speed 6.7 % - 12.0% 6.5 % - 13.5% Maturity (months) 18 - 94 20 - 104 Discount rate 9.3 % - 12.0% 9.5 % - 12.0%
Fair Value Inputs Mortgage Servicing Assets Quantitative Information	A rollforward of the carrying value of MSRs for the three years ended December 31, 2019 is presented in the following table. Carrying Value of MSRs (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Beginning balance $ 6,730 $ 5,894 $ 6,120 New MSRs 1,228 1,080 673 Total (losses) gains included in earnings (1) : Changes in valuation inputs and assumptions (1,559) 475 (41) Other changes in fair value (2) (541) (719) (858) Ending balance (3) $ 5,858 $ 6,730 $ 5,894 Contractual servicing fees earned during the year (1) $ 1,586 $ 1,517 $ 1,536 Total amount of loans being serviced for the benefit of 653,656 627,323 607,016 (1) Included in mortgage banking income in the Consolidated Statements of Income and related to assets held as of December 31, 2019, 2018, and 2017. (2) Primarily represents changes in expected future cash flows over time due to payoffs and paydowns. (3) Included in other assets in the Consolidated Statements of Financial Condition.
Fair Value Assets Measured On Annual Basis	The fair value of Pension Plan assets is presented in the following table by level in the fair value hierarchy. Annual Fair Value Measurements for Pension Plan Assets (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Level 1 Level 2 Total Level 1 Level 2 Total Pension plan assets: Mutual funds (1) $ 34,231 $ — $ 34,231 $ 27,246 $ — $ 27,246 U.S. government and government agency securities 3,720 3,685 7,405 4,389 3,626 8,015 Corporate bonds — 10,865 10,865 — 10,472 10,472 Common stocks 34,693 — 34,693 26,882 — 26,882 Common trust funds N/A N/A 5,096 N/A N/A 3,595 Total pension plan assets $ 72,644 $ 14,550 $ 92,290 $ 58,517 $ 14,098 $ 76,210 N/A – Not applicable for investments measured at fair value using net asset value ("NAV") as a practical expedient which are not classified in the fair value hierarchy. (1) Includes mutual funds, money market funds, cash, cash equivalents, and accrued interest.
Fair Value Measurements, Nonrecurring	The following table provides the fair value for each class of assets and liabilities required to be measured at fair value on a non-recurring basis in the Consolidated Statements of Financial Condition by level in the fair value hierarchy. Non-Recurring Fair Value Measurements (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Collateral-dependent impaired loans (1) $ — $ — $ 41,326 $ — $ — $ 24,565 OREO (2) — — 3,325 — — 6,012 Loans held-for-sale (3) — — 36,032 — — 3,478 Assets held-for-sale (4) — — 6,824 — — 3,722 (1) Includes impaired loans with charge-offs and impaired loans with a specific reserve during the periods presented. (2) Includes OREO with fair value adjustments subsequent to initial transfer that occurred during the periods presented. (3) Included in other assets in the Consolidated Statements of Financial Condition. (4) Included in premises, furniture, and equipment in the Consolidated Statements of Financial Condition.
Fair Value, by Balance Sheet Grouping	For certain financial instruments that are not required to be measured at fair value in the Consolidated Statements of Financial Condition, the Company must disclose the estimated fair values and the level within the fair value hierarchy as shown in the following table. Fair Value Measurements of Other Financial Instruments (Dollar amounts in thousands) As of December 31, 2019 As of December 31, 2018 Fair Value Hierarchy Carrying Fair Value Carrying Fair Value Assets Cash and due from banks 1 $ 214,894 $ 214,894 $ 211,189 $ 211,189 Interest-bearing deposits in other banks 2 84,327 84,327 78,069 78,069 Securities held-to-maturity 2 21,997 21,234 10,176 9,871 FHLB and FRB stock 2 115,409 115,409 80,302 80,302 Loans 3 12,733,200 12,535,848 11,346,668 11,052,040 Investment in BOLI 3 296,351 296,351 296,733 296,733 Accrued interest receivable 3 59,716 59,716 54,847 54,847 Other interest-earning assets 3 — — 5 5 Liabilities Deposits 2 $ 13,251,278 $ 13,247,871 $ 12,084,112 $ 12,064,604 Borrowed funds 2 1,658,758 1,658,758 906,079 906,079 Senior and subordinated debt 2 233,948 277,203 203,808 211,207 Accrued interest payable 2 10,502 10,502 10,005 10,005

Condensed Parent Company Fina_2

Condensed Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Statements of Financial Condition - Parent Company Only	The following represents the condensed financial statements of First Midwest Bancorp, Inc., the Parent Company. Statements of Financial Condition (Parent Company only) (Dollar amounts in thousands) As of December 31, 2019 2018 Assets Cash and due from banks $ 247,507 $ 158,026 Investments in and advances to subsidiaries 2,360,467 2,091,158 Other assets 45,306 55,782 Total assets $ 2,653,280 $ 2,304,966 Liabilities and Stockholders' Equity Senior and subordinated debt $ 233,948 $ 203,808 Accrued interest payable and other liabilities 48,539 46,160 Stockholders' equity 2,370,793 2,054,998 Total liabilities and stockholders' equity $ 2,653,280 $ 2,304,966
Statements of Income - Parent Company Only	Statements of Income (Parent Company only) (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Income Dividends from subsidiaries $ 236,137 $ 86,095 $ 74,091 Interest income 613 453 2,211 Securities transactions and other 23 280 (1,372) Total income 236,773 86,828 74,930 Expenses Interest expense 14,431 12,708 12,428 Salaries and employee benefits 13,903 22,430 20,978 Other expenses 11,384 9,440 9,126 Total expenses 39,718 44,578 42,532 Income before income tax benefit and equity in undistributed income of subsidiaries 197,055 42,250 32,398 Income tax benefit 10,609 13,299 14,851 Income before equity in undistributed income of subsidiaries 207,664 55,549 47,249 Equity in undistributed (loss) income of subsidiaries (7,926) 102,321 51,138 Net income 199,738 157,870 98,387 Net income applicable to non-vested restricted shares (1,681) (1,312) (916) Net income applicable to common shares $ 198,057 $ 156,558 $ 97,471
Statements of Cash Flows - Parent Company Only	Statements of Cash Flows (Parent Company only) (Dollar amounts in thousands) Years Ended December 31, 2019 2018 2017 Operating Activities Net income $ 199,738 $ 157,870 $ 98,387 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed loss (income) of subsidiaries 7,926 (102,321) (51,138) Depreciation of premises, furniture, and equipment 51 42 9 Net securities losses — — 1,523 Share-based compensation expense 13,183 12,062 11,223 Tax benefit related to share-based compensation 364 258 349 Net (increase) decrease in other assets (67,330) 35,981 18,667 Net increase (decrease) in other liabilities 49,813 (17,942) (52,377) Net cash provided by operating activities 203,745 85,950 26,643 Investing Activities Proceeds from sales and maturities of securities available-for-sale — — 42,516 Purchase of premises, furniture, and equipment — (61) (119) Net cash (paid) received for acquisitions (19,966) 39 (47,364) Net cash used in investing activities (19,966) (22) (4,967) Financing Activities Repurchases of common stock (33,928) — — Cash dividends paid (56,540) (44,293) (37,129) Restricted stock activity (3,830) (4,421) (3,952) Net cash used in financing activities (94,298) (48,714) (41,081) Net increase (decrease) in cash and cash equivalents 89,481 37,214 (19,405) Cash and cash equivalents at beginning of year 158,026 120,812 140,217 Cash and cash equivalents at end of year $ 247,507 $ 158,026 $ 120,812 Supplemental Disclosures of Cash Flow Information: Common stock issued for acquisitions, net of issuance costs $ 101,496 $ 83,303 $ 534,090

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2019subsidiarysegment
Property, Plant and Equipment [Line Items]
Number of wholly-owned subsidiaries | subsidiary	3
Number of reportable segments | segment	1
Finite-lived intangible assets amortization period	10 years
Furniture And Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Furniture And Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	10 years
Premises | Minimum
Property, Plant and Equipment [Line Items]
Useful life	25 years
Premises | Maximum
Property, Plant and Equipment [Line Items]
Useful life	40 years

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019		Jan. 01, 2018	[2]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	$ 141,000	$ 143,600
Adjustments to apply recent accounting pronouncements		47,257	[1]	$ 0
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments to apply recent accounting pronouncements		$ 47,257	[1]	$ 6,689
[1]	As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."
[2]	As a result of accounting guidance adopted in 2018, certain reclassifications were made from accumulated other comprehensive loss to retained earnings as of January 1, 2018. For further discussion of this guidance, see Note 2. "Recent Accounting Pronouncements." (2) As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 27, 2019	May 09, 2019	Oct. 12, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Jan. 16, 2019	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill				$ 796,756	$ 728,809	$ 697,608			$ 340,879
Acquisition and integration related expenses				$ 21,860	$ 9,613	$ 20,123
Park Bank
Business Acquisition [Line Items]
Announced assets to be acquired							$ 1,000,000
Announced deposits to be acquired							875,000
Announced loans to be acquired							$ 700,000
Fixed exchange ratio (in shares)	29.9675
Cash paid per share in business acquisition	$ 623.02
Announced consideration to be transferred	$ 195,000
Bridgeview Bancorp, Inc.
Business Acquisition [Line Items]
Fixed exchange ratio (in shares)		0.2767
Cash paid per share in business acquisition		$ 1.66
Total assets		$ 1,165,133
Total deposits		986,754
Total loans		710,647
Consideration transferred		$ 135,352
Common stock, shares issued (in shares)		4,728,541
Cash paid		$ 37,140
Goodwill		$ 59,142
Northern Oak Wealth Management, Inc.
Business Acquisition [Line Items]
Assets under management acquired								$ 800,000
Northern States Financial Corporation
Business Acquisition [Line Items]
Fixed exchange ratio (in shares)			0.000363
Total assets			$ 579,333
Total deposits			463,160
Total loans			284,940
Consideration transferred			$ 83,303
Common stock, shares issued (in shares)			3,310,912
Cash paid			$ 0
Goodwill			$ 30,016

Acquisitions - Acquisition Acti

Acquisitions - Acquisition Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	May 09, 2019	Oct. 12, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Goodwill			$ 796,756	$ 728,809	$ 697,608	$ 340,879
Northern States Financial Corporation
Assets
Cash and due from banks and interest-bearing deposits in other banks		$ 160,145
Equity securities		3,915
Securities available-for-sale		47,149
Securities held-to-maturity		0
FHLB and FRB stock		554
Loans		284,940
OREO		2,549
Investment in BOLI		11,104
Goodwill		30,016
Other intangible assets		12,230
Premises, furniture, and equipment		5,820
Accrued interest receivable and other assets		20,911
Total assets		579,333
Liabilities
Noninterest-bearing deposits		346,714
Interest-bearing deposits		116,446
Total deposits		463,160
Borrowed funds		18,218
Senior and subordinated debt		8,038
Accrued interest payable and other liabilities		6,614
Total liabilities		496,030
Consideration Paid
Common stock (2019 - 4,728,541, shares issued at $28.61 per share, 2018 - 3,310,912 share issued at $25.16 per share), net of issuance costs		83,303
Cash paid		0
Total consideration paid		$ 83,303
Common stock, shares issued (in shares)		3,310,912
Shares issued (in dollars per share)		$ 25.16
Bridgeview Bancorp, Inc.
Assets
Cash and due from banks and interest-bearing deposits in other banks	$ 35,097
Equity securities	6,966
Securities available-for-sale	263,090
Securities held-to-maturity	13,426
FHLB and FRB stock	1,481
Loans	710,647
OREO	6,003
Investment in BOLI	0
Goodwill	59,142
Other intangible assets	15,603
Premises, furniture, and equipment	17,681
Accrued interest receivable and other assets	35,997
Total assets	1,165,133
Liabilities
Noninterest-bearing deposits	179,267
Interest-bearing deposits	807,487
Total deposits	986,754
Borrowed funds	1,746
Senior and subordinated debt	29,360
Accrued interest payable and other liabilities	11,921
Total liabilities	1,029,781
Consideration Paid
Common stock (2019 - 4,728,541, shares issued at $28.61 per share, 2018 - 3,310,912 share issued at $25.16 per share), net of issuance costs	98,212
Cash paid	37,140
Total consideration paid	$ 135,352
Common stock, shares issued (in shares)	4,728,541
Shares issued (in dollars per share)	$ 28.61

Securities - Securities Portfol

Securities - Securities Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,851,479	$ 2,311,920
Gross Unrealized Gains	31,205	4,405
Gross Unrealized Losses	(9,298)	(44,316)
Fair Value	2,873,386	2,272,009
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	21,997	10,176
Fair Value	21,234	9,871
Debt and Equity Securities, FV-NI [Line Items]
Equity Securities	42,136	30,806
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	33,939	37,925
Gross Unrealized Gains	137	17
Gross Unrealized Losses	(1)	(175)
Fair Value	34,075	37,767
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	249,502	144,125
Gross Unrealized Gains	758	45
Gross Unrealized Losses	(1,836)	(1,607)
Fair Value	248,424	142,563
Collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,547,805	1,336,531
Gross Unrealized Gains	14,893	3,362
Gross Unrealized Losses	(5,027)	(24,684)
Fair Value	1,557,671	1,315,209
Other Mortgage Backed Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	678,804	477,665
Gross Unrealized Gains	7,728	520
Gross Unrealized Losses	(1,848)	(11,251)
Fair Value	684,684	466,934
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	228,632	229,600
Gross Unrealized Gains	5,898	461
Gross Unrealized Losses	(99)	(2,874)
Fair Value	234,431	227,187
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	21,997	10,176
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(763)	(305)
Fair Value	21,234	9,871
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	112,797	86,074
Gross Unrealized Gains	1,791	0
Gross Unrealized Losses	(487)	(3,725)
Fair Value	114,101	82,349
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Equity Securities	$ 42,136	$ 30,806

Securities - Remaining Contract

Securities - Remaining Contractual Maturity of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Available-for-Sale Securities, Amortized Cost Basis [Abstract]
One year or less	$ 131,855
After one year to five years	193,902
After five years to ten years	299,113
After ten years	0
Securities that do not have a single contractual maturity date	2,226,609
Amortized Cost	2,851,479	$ 2,311,920
Available-for-Sale Securities, Fair Value [Abstract]
One year or less	133,155
After one year to five years	195,814
After five years to ten years	302,062
After ten years	0
Securities that do not have a single contractual maturity date	2,242,355
Total	2,873,386	2,272,009
Held-to-Maturity Securities, Amortized Cost [Abstract]
One year or less	8,672
After one year to five years	6,037
After five years to ten years	4,417
After ten years	2,871
Securities that do not have a single contractual maturity date	0
Amortized Cost	21,997	10,176
Held-to-Maturity Securities, Fair Value [Abstract]
One year or less	8,371
After one year to five years	5,828
After five years to ten years	4,264
After ten years	2,771
Securities that do not have a single contractual maturity date	0
Total	$ 21,234	$ 9,871

Securities - Narrative (Details

Securities - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, pledged		$ 1,300,000,000	$ 1,200,000,000
Debt securities, held-to-maturity, pledged		$ 0	$ 0
CMOs
Debt Securities, Available-for-sale [Line Items]
Net realized (losses) gains on sales of securities	$ 1,900,000
CDOs
Debt Securities, Available-for-sale [Line Items]
Net realized (losses) gains on sales of securities	3,200,000
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Net realized (losses) gains on sales of securities	$ 1,300,000

Securities - Changes In Credit

Securities - Changes In Credit Losses Recognized In Earnings (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)security
Changes in Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance		$ 0	$ 0	$ 23,345
OTTI included in earnings:
Reduction for securities sales	[1],[2]	0	0	(23,345)
Ending balance		$ 0	$ 0	0
CDOs
OTTI included in earnings:
Reduction for securities sales				$ (47,700)
Number of CDOs sold (security) | security				11
[1]	Included in net securities losses in the Consolidated Statements of Income.
[2]	These reductions were driven by the sale of 11 collateralized debt obligations ("CDOs") with a carrying value of $47.7 million during the year ended December 31, 2017.

Securities - Securities In An U

Securities - Securities In An Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2019USD ($)security	Dec. 31, 2018USD ($)security
Fair Value
Number of Securities | security	286	882
Fair Value - Less Than 12 Months	$ 375,608	$ 501,061
Fair Value - 12 Months or Longer	608,390	1,365,068
Fair Value - Total	983,998	1,866,129
Unrealized Losses
Unrealized Losses - Less Than 12 Months	4,744	8,046
Unrealized Losses - 12 Months or Longer	4,554	36,270
Unrealized Losses - Total	$ 9,298	$ 44,316
U.S. treasury securities
Fair Value
Number of Securities | security	5	17
Fair Value - Less Than 12 Months	$ 4,966	$ 15,894
Fair Value - 12 Months or Longer	0	13,886
Fair Value - Total	4,966	29,780
Unrealized Losses
Unrealized Losses - Less Than 12 Months	1	57
Unrealized Losses - 12 Months or Longer	0	118
Unrealized Losses - Total	$ 1	$ 175
U.S. agency securities
Fair Value
Number of Securities | security	52	74
Fair Value - Less Than 12 Months	$ 97,729	$ 34,263
Fair Value - 12 Months or Longer	49,387	93,227
Fair Value - Total	147,116	127,490
Unrealized Losses
Unrealized Losses - Less Than 12 Months	1,200	320
Unrealized Losses - 12 Months or Longer	636	1,287
Unrealized Losses - Total	$ 1,836	$ 1,607
CMOs
Fair Value
Number of Securities | security	148	234
Fair Value - Less Than 12 Months	$ 187,470	$ 171,901
Fair Value - 12 Months or Longer	412,083	863,747
Fair Value - Total	599,553	1,035,648
Unrealized Losses
Unrealized Losses - Less Than 12 Months	2,177	1,671
Unrealized Losses - 12 Months or Longer	2,850	23,013
Unrealized Losses - Total	$ 5,027	$ 24,684
MBSs
Fair Value
Number of Securities | security	59	118
Fair Value - Less Than 12 Months	$ 66,340	$ 135,791
Fair Value - 12 Months or Longer	121,861	284,273
Fair Value - Total	188,201	420,064
Unrealized Losses
Unrealized Losses - Less Than 12 Months	996	1,715
Unrealized Losses - 12 Months or Longer	852	9,536
Unrealized Losses - Total	$ 1,848	$ 11,251
Municipal securities
Fair Value
Number of Securities | security	16	423
Fair Value - Less Than 12 Months	$ 9,384	$ 60,863
Fair Value - 12 Months or Longer	3,104	109,935
Fair Value - Total	12,488	170,798
Unrealized Losses
Unrealized Losses - Less Than 12 Months	89	558
Unrealized Losses - 12 Months or Longer	10	2,316
Unrealized Losses - Total	$ 99	$ 2,874
Schedule of Held-to-Maturity Securities [Line Items]
Number of Securities | security	30	5
Fair Value - Less than 12 Months	$ 12,202	$ 0
Unrealized Losses - Less than 12 Months	439	0
Fair Value - 12 Months or Longer	9,032	9,871
Unrealized Losses - 12 Months or Longer	324	305
Fair Value - Total	21,234	9,871
Unrealized Losses - Total	$ 763	$ 305
Corporate debt securities
Fair Value
Number of Securities | security	6	16
Fair Value - Less Than 12 Months	$ 9,719	$ 82,349
Fair Value - 12 Months or Longer	21,955	0
Fair Value - Total	31,674	82,349
Unrealized Losses
Unrealized Losses - Less Than 12 Months	281	3,725
Unrealized Losses - 12 Months or Longer	206	0
Unrealized Losses - Total	$ 487	$ 3,725

Loans - Loan Portfolio (Details

Loans - Loan Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 12,840,330	$ 11,446,783
Deferred loan fees included in total loans	7,972	6,715
Overdrawn demand deposits included in total loans	10,675	8,583
Commercial, industrial, and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,887,141	4,551,221
Commercial, industrial, and agricultural | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,481,525	4,120,293
Total loans	4,481,525	4,120,293
Commercial, industrial, and agricultural | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	405,616	430,928
Total loans	405,616	430,928
Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,682,072	4,596,249
Total loans	4,682,072	4,596,249
Commercial real estate loans | Office, retail, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,848,718	1,820,917
Total loans	1,848,718	1,820,917
Commercial real estate loans | Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	856,553	764,185
Total loans	856,553	764,185
Commercial real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	593,093	649,337
Total loans	593,093	649,337
Commercial real estate loans | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,383,708	1,361,810
Total loans	1,383,708	1,361,810
Total corporate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	9,569,213	9,147,470
Total loans	9,569,213	9,147,470
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,271,117	2,299,313
Total loans	3,271,117	2,299,313
Consumer loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	851,454	851,607
Total loans	851,454	851,607
Consumer loans | 1-4 family mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,927,078	1,017,181
Total loans	1,927,078	1,017,181
Consumer loans | Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	492,585	430,525
Total loans	$ 492,585	$ 430,525

Loans - Carrying Value of Loans

Loans - Carrying Value of Loans Pledged (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loans pledged to secure:
FHLB advances (blanket pledge)	$ 5,371,872	$ 4,443,268
FRB's Discount Window Primary Credit Program	1,173,250	1,166,128
Total	$ 6,545,122	$ 5,609,396

Loans - Narrative (Details)

Loans - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Eligible borrowing capacity in FHLB advances	$ 3,300,000	$ 2,500,000
FRB's Discount Window Primary Credit Program
Accounts, Notes, Loans and Financing Receivable [Line Items]
Eligible borrowing capacity through FRB's Discount Window Primary Credit Program	$ 874,256	$ 881,113

Loans - Loans Sales (Details)

Loans - Loans Sales (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total net gains on loan sales		$ 9,992	$ 5,562	$ 7,078
Corporate loan sales
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sales		14,650	17,900	52,974
Less book value of loans sold		14,149	17,498	51,781
Total net gains on loan sales	[1]	501	402	1,193
1-4 family mortgage loan sales
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sales		474,384	245,967	258,626
Less book value of loans sold		464,893	240,807	252,741
Total net gains on loan sales	[2]	$ 9,491	$ 5,160	$ 5,885
[1]	Net gains on corporate loan sales are included in other service charges, commissions, and fees in the Consolidated Statements of Income.
[2]	Net gains on 1-4 family mortgage loan sales are included in mortgage banking income in the Consolidated Statements of Income.

Acquired and Covered Loans - Na

Acquired and Covered Loans - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items]
Non-residential mortgage loans with expired loss share agreements	$ 7,800	$ 10,400
Outstanding balance of PCI loans	243,000	175,200
Renewed non-purchased credit impaired loans	523,500	458,000
FDIC indemnification asset	892	2,100	$ 3,300
Acquired and Covered Receivables
Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items]
Accretion on acquired loans	$ 35,600	$ 19,500	$ 33,900

Acquired and Covered Loans - Ac

Acquired and Covered Loans - Acquired and Covered Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Acquired Loans [Line Items]
Non-PCI	$ 1,216,133	$ 1,252,361
Total	1,383,316	1,366,229
Acquired loans
Acquired Loans [Line Items]
Non-PCI	1,212,420	1,247,492
Total	1,374,214	1,355,541
Covered loans
Acquired Loans [Line Items]
Non-PCI	3,713	4,869
Total	9,102	10,688
Receivables acquired with deteriorated credit quality
Acquired Loans [Line Items]
PCI	167,183	113,868
Receivables acquired with deteriorated credit quality | Acquired loans
Acquired Loans [Line Items]
PCI	161,794	108,049
Receivables acquired with deteriorated credit quality | Covered loans
Acquired Loans [Line Items]
PCI	$ 5,389	$ 5,819

Acquired and Covered Loans - Ch

Acquired and Covered Loans - Changes in Accretable Yield (Details) - Receivables acquired with deteriorated credit quality - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in Accretable Yield [Roll Forward]
Beginning balance		$ 43,725	$ 32,957	$ 19,386
Additions		16,037	3,699	27,316
Accretion		(20,607)	(12,354)	(15,529)
Other	[1]	(146)	19,423	1,784
Ending balance		$ 39,009	$ 43,725	$ 32,957
[1]	ncreases represent a rise in the expected future cash flows to be collected over the remaining estimated life of the underlying portfolio.

Past Due Loans, Allowance For_3

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Aging Analysis of Past Due Loans and Non-Performing Loans by Class (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	$ 12,754,845	$ 11,357,176
Past Due		85,485	89,607
Total loans		12,840,330	11,446,783
Non-accrual		82,269	56,935
90 Days or More Past Due, Still Accruing Interest		5,001	8,282
30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		35,192	40,102
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		50,293	49,505
Commercial, industrial, and agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		4,887,141	4,551,221
Commercial, industrial, and agricultural | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	4,455,381	4,085,164
Past Due		26,144	35,129
Total loans		4,481,525	4,120,293
Non-accrual		29,995	33,507
90 Days or More Past Due, Still Accruing Interest		2,207	422
Commercial, industrial, and agricultural | Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	398,676	428,357
Past Due		6,940	2,571
Total loans		405,616	430,928
Non-accrual		5,954	1,564
90 Days or More Past Due, Still Accruing Interest		358	101
Commercial, industrial, and agricultural | 30-89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		11,468	8,832
Commercial, industrial, and agricultural | 30-89 Days Past Due | Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		850	940
Commercial, industrial, and agricultural | 90 Days or More Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		14,676	26,297
Commercial, industrial, and agricultural | 90 Days or More Past Due | Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		6,090	1,631
Commercial real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	4,649,826	4,561,677
Past Due		32,246	34,572
Total loans		4,682,072	4,596,249
Non-accrual		33,435	12,615
90 Days or More Past Due, Still Accruing Interest		1,075	6,467
Commercial real estate loans | Office, retail, and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	1,830,321	1,803,059
Past Due		18,397	17,858
Total loans		1,848,718	1,820,917
Non-accrual		25,857	6,510
90 Days or More Past Due, Still Accruing Interest		546	4,081
Commercial real estate loans | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	853,762	759,402
Past Due		2,791	4,783
Total loans		856,553	764,185
Non-accrual		2,697	3,107
90 Days or More Past Due, Still Accruing Interest		0	189
Commercial real estate loans | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	588,065	645,774
Past Due		5,028	3,563
Total loans		593,093	649,337
Non-accrual		152	144
90 Days or More Past Due, Still Accruing Interest		0	0
Commercial real estate loans | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	1,377,678	1,353,442
Past Due		6,030	8,368
Total loans		1,383,708	1,361,810
Non-accrual		4,729	2,854
90 Days or More Past Due, Still Accruing Interest		529	2,197
Commercial real estate loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		11,263	18,036
Commercial real estate loans | 30-89 Days Past Due | Office, retail, and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		2,943	8,209
Commercial real estate loans | 30-89 Days Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		211	1,487
Commercial real estate loans | 30-89 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		4,876	3,419
Commercial real estate loans | 30-89 Days Past Due | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		3,233	4,921
Commercial real estate loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		20,983	16,536
Commercial real estate loans | 90 Days or More Past Due | Office, retail, and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		15,454	9,649
Commercial real estate loans | 90 Days or More Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		2,580	3,296
Commercial real estate loans | 90 Days or More Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		152	144
Commercial real estate loans | 90 Days or More Past Due | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		2,797	3,447
Total corporate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	9,503,883	9,075,198
Past Due		65,330	72,272
Total loans		9,569,213	9,147,470
Non-accrual		69,384	47,686
90 Days or More Past Due, Still Accruing Interest		3,640	6,990
Total corporate loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		23,581	27,808
Total corporate loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		41,749	44,464
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	3,250,962	2,281,978
Past Due		20,155	17,335
Total loans		3,271,117	2,299,313
Non-accrual		12,885	9,249
90 Days or More Past Due, Still Accruing Interest		1,361	1,292
Consumer loans | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	841,908	843,217
Past Due		9,546	8,390
Total loans		851,454	851,607
Non-accrual		8,443	5,393
90 Days or More Past Due, Still Accruing Interest		146	104
Consumer loans | 1-4 family mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	1,917,648	1,009,925
Past Due		9,430	7,256
Total loans		1,927,078	1,017,181
Non-accrual		4,442	3,856
90 Days or More Past Due, Still Accruing Interest		1,203	1,147
Consumer loans | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	491,406	428,836
Past Due		1,179	1,689
Total loans		492,585	430,525
Non-accrual		0	0
90 Days or More Past Due, Still Accruing Interest		12	41
Consumer loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		11,611	12,294
Consumer loans | 30-89 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		4,992	6,285
Consumer loans | 30-89 Days Past Due | 1-4 family mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		5,452	4,361
Consumer loans | 30-89 Days Past Due | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		1,167	1,648
Consumer loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		8,544	5,041
Consumer loans | 90 Days or More Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		4,554	2,105
Consumer loans | 90 Days or More Past Due | 1-4 family mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		3,978	2,895
Consumer loans | 90 Days or More Past Due | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due		$ 12	$ 41
[1]	PCI loans with an accretable yield are considered current.

Past Due Loans, Allowance For_4

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	$ 103,419	$ 96,729	$ 87,083
Charge-offs	(46,208)	(47,985)	(30,823)
Recoveries	7,984	6,621	9,179
Net charge-offs	(38,224)	(41,364)	(21,644)
Provision for loan losses and other	44,027	48,054	31,290
Ending Balance	109,222	103,419	96,729
Reserve for Unfunded Commitments
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	1,200	1,000	1,000
Charge-offs	0	0	0
Recoveries	0	0	0
Net charge-offs	0	0	0
Provision for loan losses and other	0	200	0
Ending Balance	1,200	1,200	1,000
Commercial, Industrial, and Agricultural
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	63,276	55,791	40,709
Charge-offs	(28,008)	(36,477)	(22,885)
Recoveries	4,815	2,946	4,150
Net charge-offs	(23,193)	(33,531)	(18,735)
Provision for loan losses and other	22,747	41,016	33,817
Ending Balance	62,830	63,276	55,791
Commercial Real Estate Loans
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	17,471
Ending Balance	18,635	17,471
Commercial Real Estate Loans | Office, Retail, and Industrial
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	7,900	10,996	17,595
Charge-offs	(2,800)	(2,286)	(190)
Recoveries	253	334	2,935
Net charge-offs	(2,547)	(1,952)	2,745
Provision for loan losses and other	2,227	(1,144)	(9,344)
Ending Balance	7,580	7,900	10,996
Commercial Real Estate Loans | Multi-family
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	2,464	2,534	3,261
Charge-offs	(340)	(5)	0
Recoveries	478	3	39
Net charge-offs	138	(2)	39
Provision for loan losses and other	348	(68)	(766)
Ending Balance	2,950	2,464	2,534
Commercial Real Estate Loans | Construction
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	2,173	3,481	3,444
Charge-offs	(10)	(1)	(38)
Recoveries	19	125	270
Net charge-offs	9	124	232
Provision for loan losses and other	(485)	(1,432)	(195)
Ending Balance	1,697	2,173	3,481
Commercial Real Estate Loans | Other Commercial Real Estate
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	4,934	6,381	7,739
Charge-offs	(800)	(410)	(755)
Recoveries	357	1,532	244
Net charge-offs	(443)	1,122	(511)
Provision for loan losses and other	1,917	(2,569)	(847)
Ending Balance	6,408	4,934	6,381
Consumer Loans
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	21,472
Ending Balance	26,557	21,472
Consumer Loans | Consumer Loans
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	21,472	16,546	13,335
Charge-offs	(14,250)	(8,806)	(6,955)
Recoveries	2,062	1,681	1,541
Net charge-offs	(12,188)	(7,125)	(5,414)
Provision for loan losses and other	17,273	12,051	8,625
Ending Balance	$ 26,557	$ 21,472	$ 16,546

Past Due Loans, Allowance For_5

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Loans and Related Allowance for Credit Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	$ 64,321	$ 42,509
Loans Collectively Evaluated for Impairment	12,608,826	11,290,406
Total loans	12,840,330	11,446,783
Allowance for Credit Losses Individually Evaluated for Impairment	3,992	4,709
Allowance for Credit Losses Collectively Evaluated for Impairment	102,033	94,578
Total Allowance for Credit Losses	109,222	103,419	$ 96,729	$ 87,083
PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	167,183	113,868
Total Allowance for Credit Losses	3,197	4,132
Reserve for unfunded commitments
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	0	0
Loans Collectively Evaluated for Impairment	0	0
Total loans	0	0
Allowance for Credit Losses Individually Evaluated for Impairment	0	0
Allowance for Credit Losses Collectively Evaluated for Impairment	1,200	1,200
Total Allowance for Credit Losses	1,200	1,200	1,000	1,000
Reserve for unfunded commitments | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	0	0
Total Allowance for Credit Losses	0	0
Commercial, industrial, and agricultural
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	34,142	32,415
Loans Collectively Evaluated for Impairment	4,807,114	4,514,349
Total loans	4,887,141	4,551,221
Allowance for Credit Losses Individually Evaluated for Impairment	3,414	3,961
Allowance for Credit Losses Collectively Evaluated for Impairment	59,108	58,947
Total Allowance for Credit Losses	62,830	63,276	55,791	40,709
Commercial, industrial, and agricultural | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	45,885	4,457
Total Allowance for Credit Losses	308	368
Commercial real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	30,179	10,094
Loans Collectively Evaluated for Impairment	4,552,796	4,496,277
Total loans	4,682,072	4,596,249
Allowance for Credit Losses Individually Evaluated for Impairment	578	748
Allowance for Credit Losses Collectively Evaluated for Impairment	16,301	14,337
Total Allowance for Credit Losses	18,635	17,471
Commercial real estate loans | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	99,097	89,878
Total Allowance for Credit Losses	1,756	2,386
Commercial real estate loans | Office, retail, and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	24,820	5,057
Loans Collectively Evaluated for Impairment	1,795,557	1,799,304
Total loans	1,848,718	1,820,917
Allowance for Credit Losses Individually Evaluated for Impairment	578	748
Allowance for Credit Losses Collectively Evaluated for Impairment	6,899	5,984
Total Allowance for Credit Losses	7,580	7,900	10,996	17,595
Commercial real estate loans | Office, retail, and industrial | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	28,341	16,556
Total Allowance for Credit Losses	103	1,168
Commercial real estate loans | Multi-family
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	1,995	3,492
Loans Collectively Evaluated for Impairment	851,857	747,030
Total loans	856,553	764,185
Allowance for Credit Losses Individually Evaluated for Impairment	0	0
Allowance for Credit Losses Collectively Evaluated for Impairment	2,854	2,154
Total Allowance for Credit Losses	2,950	2,464	2,534	3,261
Commercial real estate loans | Multi-family | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	2,701	13,663
Total Allowance for Credit Losses	96	310
Commercial real estate loans | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	123	0
Loans Collectively Evaluated for Impairment	581,747	644,499
Total loans	593,093	649,337
Allowance for Credit Losses Individually Evaluated for Impairment	0	0
Allowance for Credit Losses Collectively Evaluated for Impairment	1,681	2,019
Total Allowance for Credit Losses	1,697	2,173	3,481	3,444
Commercial real estate loans | Construction | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	11,223	4,838
Total Allowance for Credit Losses	16	154
Commercial real estate loans | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	3,241	1,545
Loans Collectively Evaluated for Impairment	1,323,635	1,305,444
Total loans	1,383,708	1,361,810
Allowance for Credit Losses Individually Evaluated for Impairment	0	0
Allowance for Credit Losses Collectively Evaluated for Impairment	4,867	4,180
Total Allowance for Credit Losses	6,408	4,934	$ 6,381	$ 7,739
Commercial real estate loans | Other commercial real estate | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	56,832	54,821
Total Allowance for Credit Losses	1,541	754
Total corporate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	64,321	42,509
Loans Collectively Evaluated for Impairment	9,359,910	9,010,626
Total loans	9,569,213	9,147,470
Allowance for Credit Losses Individually Evaluated for Impairment	3,992	4,709
Allowance for Credit Losses Collectively Evaluated for Impairment	75,409	73,284
Total Allowance for Credit Losses	81,465	80,747
Total corporate loans | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	144,982	94,335
Total Allowance for Credit Losses	2,064	2,754
Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment	0	0
Loans Collectively Evaluated for Impairment	3,248,916	2,279,780
Total loans	3,271,117	2,299,313
Allowance for Credit Losses Individually Evaluated for Impairment	0	0
Allowance for Credit Losses Collectively Evaluated for Impairment	25,424	20,094
Total Allowance for Credit Losses	26,557	21,472
Consumer loans | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	22,201	19,533
Total Allowance for Credit Losses	$ 1,133	$ 1,378

Past Due Loans, Allowance For_6

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Impaired Loans Individually Evaluated by Class (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	$ 34,244	$ 15,766
Recorded Investment in Loans with a Specific Reserve	30,077	26,743
Unpaid Principal Balance	104,472	64,344
Specific Reserve	3,992	4,709
Commercial, industrial, and agricultural | Commercial and industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	12,885	7,550
Recorded Investment in Loans with a Specific Reserve	15,516	23,349
Unpaid Principal Balance	52,559	49,102
Specific Reserve	2,456	3,960
Commercial, industrial, and agricultural | Agricultural
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	1,889	1,318
Recorded Investment in Loans with a Specific Reserve	3,852	198
Unpaid Principal Balance	9,293	3,997
Specific Reserve	958	1
Commercial real estate loans
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	19,470	6,898
Recorded Investment in Loans with a Specific Reserve	10,709	3,196
Unpaid Principal Balance	42,620	11,245
Specific Reserve	578	748
Commercial real estate loans | Office, retail, and industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	14,111	1,861
Recorded Investment in Loans with a Specific Reserve	10,709	3,196
Unpaid Principal Balance	37,007	6,141
Specific Reserve	578	748
Commercial real estate loans | Multi-family
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	1,995	3,492
Recorded Investment in Loans with a Specific Reserve	0	0
Unpaid Principal Balance	1,995	3,492
Specific Reserve	0	0
Commercial real estate loans | Construction
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	123	0
Recorded Investment in Loans with a Specific Reserve	0	0
Unpaid Principal Balance	123	0
Specific Reserve	0	0
Commercial real estate loans | Other commercial real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	3,241	1,545
Recorded Investment in Loans with a Specific Reserve	0	0
Unpaid Principal Balance	3,495	1,612
Specific Reserve	$ 0	$ 0

Past Due Loans, Allowance For_7

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Impaired Loans Individually Evaluated by Class (Continued) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		$ 54,427	$ 48,445	$ 49,404
Interest Income Recognized	[1]	413	1,621	1,690
Commercial, industrial, and agricultural | Commercial and industrial
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		26,700	33,732	33,956
Interest Income Recognized	[1]	115	225	1,059
Commercial, industrial, and agricultural | Agricultural
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		4,374	2,026	279
Interest Income Recognized	[1]	20	32	101
Commercial real estate loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		23,352	12,688	15,169
Interest Income Recognized	[1]	278	1,364	530
Commercial real estate loans | Office, retail, and industrial
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		17,453	8,105	13,106
Interest Income Recognized	[1]	73	892	325
Commercial real estate loans | Multi-family
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		3,164	2,404	441
Interest Income Recognized	[1]	112	66	28
Commercial real estate loans | Construction
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		74	0	7
Interest Income Recognized	[1]	3	0	136
Commercial real estate loans | Other commercial real estate
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		2,662	2,179	1,615
Interest Income Recognized	[1]	$ 90	$ 406	$ 41
[1]	Recorded using the cash basis of accounting.

Past Due Loans, Allowance For_8

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Credit Quality Indicators by Class, Excluding Covered Loans (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Commercial, industrial, and agricultural | Commercial and industrial
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		$ 4,481,525	$ 4,120,293
Commercial, industrial, and agricultural | Commercial and industrial | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		4,324,709	3,952,066
Commercial, industrial, and agricultural | Commercial and industrial | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	47,665	74,878
Commercial, industrial, and agricultural | Commercial and industrial | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	79,156	59,842
Commercial, industrial, and agricultural | Commercial and industrial | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	29,995	33,507
Commercial, industrial, and agricultural | Agricultural
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		405,616	430,928
Commercial, industrial, and agricultural | Agricultural | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		350,827	407,542
Commercial, industrial, and agricultural | Agricultural | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	32,764	10,070
Commercial, industrial, and agricultural | Agricultural | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	16,071	11,752
Commercial, industrial, and agricultural | Agricultural | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	5,954	1,564
Commercial real estate loans
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		4,682,072	4,596,249
Commercial real estate loans | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		4,446,552	4,399,131
Commercial real estate loans | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	108,274	109,232
Commercial real estate loans | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	93,811	75,271
Commercial real estate loans | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	33,435	12,615
Commercial real estate loans | Office, retail, and industrial
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		1,848,718	1,820,917
Commercial real estate loans | Office, retail, and industrial | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		1,747,287	1,735,426
Commercial real estate loans | Office, retail, and industrial | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	42,230	35,853
Commercial real estate loans | Office, retail, and industrial | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	33,344	43,128
Commercial real estate loans | Office, retail, and industrial | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	25,857	6,510
Commercial real estate loans | Multi-family
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		856,553	764,185
Commercial real estate loans | Multi-family | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		839,615	745,131
Commercial real estate loans | Multi-family | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	8,279	9,273
Commercial real estate loans | Multi-family | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	5,962	6,674
Commercial real estate loans | Multi-family | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	2,697	3,107
Commercial real estate loans | Construction
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		593,093	649,337
Commercial real estate loans | Construction | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		564,495	624,446
Commercial real estate loans | Construction | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	17,977	16,370
Commercial real estate loans | Construction | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	10,469	8,377
Commercial real estate loans | Construction | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	152	144
Commercial real estate loans | Other commercial real estate
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		1,383,708	1,361,810
Commercial real estate loans | Other commercial real estate | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		1,295,155	1,294,128
Commercial real estate loans | Other commercial real estate | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	39,788	47,736
Commercial real estate loans | Other commercial real estate | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	44,036	17,092
Commercial real estate loans | Other commercial real estate | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	4,729	2,854
Total corporate loans
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		9,569,213	9,147,470
Total corporate loans | Pass
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class		9,122,088	8,758,739
Total corporate loans | Special Mention
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[1]	188,703	194,180
Total corporate loans | Substandard
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[2]	189,038	146,865
Total corporate loans | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans [Line Items
Credit Quality Indicators by Class	[3]	$ 69,384	$ 47,686
[1]	Loans categorized as special mention exhibit potential weaknesses that require the close attention of management since these potential weaknesses may result in the deterioration of repayment prospects in the future.
[2]	Loans categorized as substandard exhibit a well-defined weakness that may jeopardize the liquidation of the debt. These loans continue to accrue interest because they are well-secured and collection of principal and interest is expected within a reasonable time.
[3]	Loans categorized as non-accrual exhibit a well-defined weakness that may jeopardize the liquidation of the debt or result in a loss if the deficiencies are not corrected.

Past Due Loans, Allowance For_9

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) (Details) - Consumer loans - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	$ 3,271,117	$ 2,299,313
Performing
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	3,258,232	2,290,064
Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	12,885	9,249
Home equity
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	851,454	851,607
Home equity | Performing
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	843,011	846,214
Home equity | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	8,443	5,393
1-4 family mortgages
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	1,927,078	1,017,181
1-4 family mortgages | Performing
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	1,922,636	1,013,325
1-4 family mortgages | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	4,442	3,856
Installment
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	492,585	430,525
Installment | Performing
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	492,585	430,525
Installment | Non-accrual
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - Credit Quality Indicators by Class, Excluding Covered Loans (Continued) [Line Items]
Credit Quality Indicators by Class	$ 0	$ 0

Past Due Loans, Allowance Fo_10

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - TDRs By Class (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Accruing		$ 1,233	$ 1,866
Non-accrual	[1]	20,514	6,612
Total		21,747	8,478	$ 26,329
Commercial, industrial, and agricultural | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Accruing		227	246
Non-accrual	[1]	16,420	5,994
Total		16,647	6,240
Commercial, industrial, and agricultural | Agricultural
Financing Receivable, Modifications [Line Items]
Accruing		0	0
Non-accrual	[1]	0	0
Total		0	0
Commercial real estate loans
Financing Receivable, Modifications [Line Items]
Accruing		333	738
Non-accrual	[1]	3,600	0
Total		3,933	738
Commercial real estate loans | Office, retail, and industrial
Financing Receivable, Modifications [Line Items]
Accruing		0	0
Non-accrual	[1]	3,600	0
Total		3,600	0
Commercial real estate loans | Multi-family
Financing Receivable, Modifications [Line Items]
Accruing		163	557
Non-accrual	[1]	0	0
Total		163	557
Commercial real estate loans | Construction
Financing Receivable, Modifications [Line Items]
Accruing		0	0
Non-accrual	[1]	0	0
Total		0	0
Commercial real estate loans | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Accruing		170	181
Non-accrual	[1]	0	0
Total		170	181
Total corporate loans
Financing Receivable, Modifications [Line Items]
Accruing		560	984
Non-accrual	[1]	20,020	5,994
Total		20,580	6,978
Consumer loans
Financing Receivable, Modifications [Line Items]
Accruing		673	882
Non-accrual	[1]	494	618
Total		1,167	1,500
Consumer loans | Home equity
Financing Receivable, Modifications [Line Items]
Accruing		36	113
Non-accrual	[1]	240	327
Total		276	440
Consumer loans | 1-4 family mortgages
Financing Receivable, Modifications [Line Items]
Accruing		637	769
Non-accrual	[1]	0	291
Total		637	1,060
Consumer loans | Installment
Financing Receivable, Modifications [Line Items]
Accruing		0	0
Non-accrual	[1]	254	0
Total		$ 254	$ 0
[1]	These TDRs are included in non-accrual loans in the preceding tables.

Past Due Loans, Allowance Fo_11

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Specific reserves related to TDRs	$ 2,200,000	$ 0
Commitments to lend additional funds on TDR loans	$ 530,000	$ 3,800,000

Past Due Loans, Allowance Fo_12

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - TDRs That Were Restructured (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)loan	Dec. 31, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	8	14
Pre-Modification Recorded Investment	$ 18,101	$ 30,389
Funds Disbursed	0	9,035
Interest and Escrow Capitalized	0	0
Charge-offs	2,297	6,232
Post-Modification Recorded Investment	$ 15,804	$ 33,192
Commercial, industrial, and agricultural | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	5	12
Pre-Modification Recorded Investment	$ 13,616	$ 26,733
Funds Disbursed	0	9,035
Interest and Escrow Capitalized	0	0
Charge-offs	1,424	6,232
Post-Modification Recorded Investment	$ 12,192	$ 29,536
Commercial real estate loans | Office, retail, and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	2	2
Pre-Modification Recorded Investment	$ 4,473	$ 3,656
Funds Disbursed	0	0
Interest and Escrow Capitalized	0	0
Charge-offs	873	0
Post-Modification Recorded Investment	$ 3,600	$ 3,656
Commercial real estate loans | Multi-family
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1
Pre-Modification Recorded Investment	$ 12
Funds Disbursed	0
Interest and Escrow Capitalized	0
Charge-offs	0
Post-Modification Recorded Investment	$ 12

Past Due Loans, Allowance Fo_13

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs - TDR Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Troubled Debt Restructuring Activity [Roll Forward]
Beginning balance	$ 8,478	$ 26,329
Additions	15,804		$ 33,192
Ending balance	21,747	8,478	26,329
Accruing
Troubled Debt Restructuring Activity [Roll Forward]
Beginning balance	1,866	1,796	2,291
Additions	12	0	15,819
Net payments	(262)	(50)	(1,923)
Returned to performing status	0	0	0
Net transfers (to) from non-accrual	(383)	120	(14,391)
Ending balance	1,233	1,866	1,796
Non-accrual
Troubled Debt Restructuring Activity [Roll Forward]
Beginning balance	6,612	24,533	6,297
Additions	18,089	527	14,570
Net payments	(1,013)	(14,403)	(4,380)
Charge-offs	(3,557)	(3,925)	(6,345)
Transfers to OREO	0	0	0
Loans sold	0	0	0
Net transfers from (to) accruing	383	(120)	14,391
Ending balance	$ 20,514	$ 6,612	$ 24,533

Premises, Furniture, and Equi_3

Premises, Furniture, and Equipment - Premises, Furniture, and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Land	$ 30,807	$ 28,187
Premises	132,427	122,003
Furniture and equipment	137,349	127,421
Total cost	300,583	277,611
Accumulated depreciation	(159,411)	(148,831)
Net book value of premises, furniture, and equipment	141,172	128,780
Assets held-for-sale	6,824	3,722
Premises, furniture, and equipment, net	$ 147,996	$ 132,502

Premises, Furniture, and Equi_4

Premises, Furniture, and Equipment - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation of premises, furniture, and equipment	$ 16,366	$ 15,865	$ 13,995

Narrative (Details)

Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2016USD ($)branch	Dec. 31, 2019USD ($)	Jan. 01, 2019USD ($)		Jan. 01, 2018USD ($)	[2]
Leases [Abstract]
Operating lease, weighted average remaining lease term			11 years 2 months 8 days
Operating lease, weighted average discount rate (as a percent)			3.19%
Right-of-use asset			$ 141,000	$ 143,600
Lessee, Lease, Description [Line Items]
Sale and leaseback transaction, number of branches sold | branch		55
Sale and leaseback transaction, pre-tax gain	$ 65,500	$ 88,000
Sale and leaseback transaction, transaction related expenses		$ 5,500
Adjustments to apply recent accounting pronouncements				47,257	[1]	$ 0
Retained Earnings
Lessee, Lease, Description [Line Items]
Adjustments to apply recent accounting pronouncements				$ 47,257	[1]	$ 6,689
[1]	As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."
[2]	As a result of accounting guidance adopted in 2018, certain reclassifications were made from accumulated other comprehensive loss to retained earnings as of January 1, 2018. For further discussion of this guidance, see Note 2. "Recent Accounting Pronouncements." (2) As a result of accounting guidance adopted in 2019, the remaining deferred gain on a sale-leaseback transaction was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2019. For further discussion of this guidance, see Note 2, "Recent Accounting Pronouncements."

Schedule of Lease Liability (De

Schedule of Lease Liability (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 17,855
2021	17,873
2022	18,007
2023	18,175
2024	18,090
2025 and thereafter	103,967
Total minimum lease payments	193,967
Discount	(32,403)	[1]
Lease liability	$ 161,564	[2],[3]
[1]	Represents the net present value adjustment related to minimum lease payments.
[2]	Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income
[3]	Included in accrued interest payable and other liabilities in the Consolidated Statements of Financial Condition.

Schedule of Net Operating Lease

Schedule of Net Operating Lease Expense (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Lease expense charged to operations		$ 17,681	$ 24,880	$ 18,666
Accretion of operating lease intangible	[1]	(162)	(972)	(1,180)
Accretion of deferred gain on sale-leaseback transaction	[1]		(9,126)	(5,872)
Rental income from premises leased to others	[1]	(720)	(510)	(682)
Net operating lease expense		$ 16,799	$ 14,272	$ 10,932
[1]	Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning balance	$ 728,809	$ 697,608	$ 340,879
Acquisitions	67,947	31,201	356,729
Ending balance	$ 796,756	$ 728,809	$ 697,608

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-lived Intangible Assets [Roll Forward]
Balance at the beginning of the year, gross	$ 110,206	$ 97,976	$ 58,959
Balance at the beginning of the year, accumulated amortization	48,271	40,827	32,962
Balance at the beginning of the year, net	61,935	57,149	25,997
Additions	27,052	12,230	39,017
Amortization expense	(10,481)	(7,444)	(7,865)
Balance at the end of the year, gross	137,258	110,206	97,976
Balance at the end of the year, accumulated amortization	58,752	48,271	40,827
Balance at the end of the year, net	$ 78,506	$ 61,935	$ 57,149
Weighted-average remaining life (in years)	7 years 6 months	7 years 9 months 18 days	8 years 3 months 18 days
Minimum
Finite-lived Intangible Assets [Roll Forward]
Estimated useful lives (in years)	6 months	8 months 12 days	2 months 12 days
Maximum
Finite-lived Intangible Assets [Roll Forward]
Estimated useful lives (in years)	9 years 3 months 18 days	9 years 9 months 18 days	9 years 3 months 18 days

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Amortization of Other Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2020	$ 10,951
2021	10,875
2022	10,796
2023	10,418
2024	10,172
2025 and thereafter	25,294
Total	$ 78,506	$ 61,935	$ 57,149	$ 25,997

Deposits - Summary of Deposits

Deposits - Summary of Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Demand deposits	$ 3,802,422	$ 3,642,989
Savings deposits	2,062,848	2,053,494
NOW accounts	2,259,505	2,063,213
Money market deposits	2,093,049	1,783,512
Time deposits less than $100,000	1,615,609	1,348,664
Time deposits greater than $100,000	1,417,845	1,192,240
Total deposits	$ 13,251,278	$ 12,084,112

Deposits - Maturities of Time D

Deposits - Maturities of Time Deposits (Details) $ in Thousands	Dec. 31, 2019USD ($)
Maturities of Time Deposits [Abstract]
2020	$ 2,800,474
2021	150,806
2022	34,140
2023	17,894
2024	29,792
2025 and thereafter	348
Total	$ 3,033,454

Borrowed Funds - Summary of Bor

Borrowed Funds - Summary of Borrowed Funds (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Securities sold under agreements to repurchase	$ 103,515	$ 121,079
FHLB advances	1,395,243	785,000
Total borrowed funds	1,658,758	906,079
Federal Funds Purchased	$ 160,000	$ 0

Borrowed Funds - Narrative (Det

Borrowed Funds - Narrative (Details) - USD ($)	Sep. 27, 2016	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Line of credit maximum borrowing capacity	$ 50,000,000
Line of credit unused facility fee	0.35%
Line of credit amount outstanding		$ 0	$ 0
One-Month LIBOR Plus 1.75%
Short-term Debt [Line Items]
Line of credit interest rate spread	1.75%
Minimum
Short-term Debt [Line Items]
Federal funds purchased, maturity period		1 day
Maximum
Short-term Debt [Line Items]
Federal funds purchased, maturity period		90 days
FHLB Advances | Minimum
Short-term Debt [Line Items]
FHLB fixed interest rate		0.70%
FHLB maturity date range, start		Jan. 1, 2020
FHLB Advances | Maximum
Short-term Debt [Line Items]
FHLB fixed interest rate		2.04%
FHLB maturity date range, end		Nov. 1, 2029

Borrowed Funds - Short-Term Cre

Borrowed Funds - Short-Term Credit Lines Available for Use (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
FRB's Discount Window Primary Credit Program
Line of Credit Facility [Line Items]
Amount outstanding	$ 874,256	$ 881,113
Available federal funds lines
Line of Credit Facility [Line Items]
Amount outstanding	718,000	684,000
Correspondent bank line of credit
Line of Credit Facility [Line Items]
Amount outstanding	$ 50,000	$ 50,000

Senior and Subordinated Debt -

Senior and Subordinated Debt - Schedule of Senior and Subordinated Debt (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 86,311		$ 56,526
Senior and subordinated debt		233,948		203,808
BST, BCT, GLST II, GLST III, and NSST I
Debt Instrument [Line Items]
Debt instrument, unamortized discount		7,200
GLST II, GLST III, and NSST I
Debt Instrument [Line Items]
Debt instrument, unamortized discount				6,000
Subordinated notes due in 2026
Debt Instrument [Line Items]
Subordinated notes		$ 147,637		$ 147,282
Interest rate		5.875%	[1],[2]	5.875%
Issuance date		Sep. 29, 2016		Sep. 29, 2016
Maturity date		Sep. 29, 2026		Sep. 29, 2026
Junior Subordinated Debentures, First Midwest Capital Trust I | First Midwest Capital Trust I (FMCT)
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 37,805		$ 37,803
Interest rate		6.95%		6.95%	[1],[2]
Issuance date		Nov. 11, 2003		Nov. 11, 2003
Maturity date		Dec. 1, 2033		Dec. 1, 2033
Junior Subordinated Debentures, Great Lakes Statutory Trust II | Great Lakes Statutory Trust II (GLST II)
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 4,674		$ 4,580
Basis spread on variable interest rate	[1],[2]	1.40%		1.40%
Issuance date		Dec. 15, 2005		Dec. 15, 2005
Maturity date		Dec. 15, 2035		Dec. 15, 2035
Junior Subordinated Debentures, Great Lakes Statutory Trust III | Great Lakes Statutory Trust III (GLST III)
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 6,187		$ 6,071
Basis spread on variable interest rate	[1],[2]	1.70%		1.70%
Issuance date		Jun. 15, 2007		Jun. 15, 2007
Maturity date		Sep. 15, 2037		Sep. 15, 2037
Junior Subordinated Debentures, Northern States Statutory Trust I | Northern States Statutory Trust I (NSST I)
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 8,206		$ 8,072
Basis spread on variable interest rate	[1],[2]	1.80%		1.80%
Issuance date		Sep. 7, 2005		Sep. 7, 2005
Maturity date		Sep. 7, 2035		Sep. 7, 2035
Junior Subordinated Debentures, Bridgeview Statutory Trust I | Bridgeview Statutory Trust I (BST)
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 14,542
Basis spread on variable interest rate	[1],[2]	3.58%
Issuance date		Dec. 19, 2002
Maturity date		Jan. 7, 2033
Junior Subordinated Debentures, Bridgeview Capital Trust II | Bridgeview Capital Trust II (BCT)
Debt Instrument [Line Items]
Total junior subordinated debentures		$ 14,897
Basis spread on variable interest rate	[1],[2]	3.35%
Issuance date		Jul. 31, 2001
Maturity date		Jul. 31, 2031
[1]	The interest rates are variable rates based on three-month LIBOR plus the margin indicated
[2]	The junior subordinated debentures related to BST, BCT, GLST II, GLST III, and NSST I were assumed by the Company through acquisitions. These amounts include acquisition adjustment discounts that total $7.2 million and $6.0 million as of December 31, 2019 and 2018, respectively.

Material Transactions Affecti_2

Material Transactions Affecting Stockholders' Equity (Details) - USD ($)	May 09, 2019	Oct. 12, 2018	May 17, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Feb. 19, 2020	Mar. 19, 2019
Class of Stock [Line Items]
Stock repurchase program, authorized amount																		$ 180,000,000
Common stock repurchased (in shares)																1,700,000
Total cost of common stock repurchased																$ 33,928,000
Common stock, increase shares authorized (in shares)			100,000,000
Common stock and preferred stock, shares authorized (in shares)			251,000,000
Preferred stock, shares authorized (in shares)			1,000,000	1,000,000				1,000,000								1,000,000
Common stock, shares authorized (in shares)			250,000,000	250,000,000				250,000,000								250,000,000
Common stock, par value (in dollars per share)			$ 0.01	$ 0.01				$ 0.01								$ 0.01
Common dividends declared per common share (in dollars per share)				$ 0.14	$ 0.14	$ 0.14	$ 0.12	$ 0.12	$ 0.11	$ 0.11	$ 0.11	$ 0.10	$ 0.10	$ 0.10	$ 0.09
Subsequent Event
Class of Stock [Line Items]
Stock repurchase program, authorized amount																	$ 200,000,000
Stock repurchase program replaced																	$ 180,000,000
Bridgeview Bancorp, Inc.
Class of Stock [Line Items]
Common stock, shares issued (in shares)	4,728,541
Shares issued (in dollars per share)	$ 28.61
Northern States Financial Corporation
Class of Stock [Line Items]
Common stock, shares issued (in shares)		3,310,912
Shares issued (in dollars per share)		$ 25.16

Earnings Per Common Share - Bas

Earnings Per Common Share - Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income		$ 199,738	$ 157,870	$ 98,387
Net income applicable to non-vested restricted shares		(1,681)	(1,312)	(916)
Net income applicable to common shares		$ 198,057	$ 156,558	$ 97,471
Weighted-average common shares outstanding:
Weighted-average common shares outstanding (basic) (in shares)		108,156	102,850	101,423
Dilutive effect of common stock equivalents (in shares)		428	4	20
Weighted-average diluted common shares outstanding (in shares)		108,584	102,854	101,443
Basic EPS (in dollars per share)		$ 1.83	$ 1.52	$ 0.96
Diluted EPS (in dollars per share)		$ 1.82	$ 1.52	$ 0.96
Anti-dilutive shares not included in the computation of diluted EPS (in shares)	[1]	0	27	229
[1]	This amount represents outstanding stock options for which the exercise price is greater than the average market price of the Company's common stock. The final outstanding stock options were exercised during the first quarter of 2018.

Income Taxes - Components of In

Income Taxes - Components of Income Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income tax expense (benefit):
Federal	$ 50,141	$ 13,497	$ 93,540
State	5,116	(619)	104
Total	55,257	12,878	93,644
Deferred income tax expense (benefit):
Federal	(1,879)	14,489	(12,219)
State	12,823	11,820	8,142
Total	10,944	26,309	(4,077)
Total income tax expense	$ 66,201	$ 39,187	$ 89,567

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Income Taxes [Line Items]
Acquired thrift's tax bad debt reserve	$ 5,800	$ 2,500	$ 5,800
Deferred tax assets, net	60,129		43,382
Unrecognized tax benefit that would affect effective tax rate	13,100	12,900	13,000
Bridgeview Bancorp, Inc.
Income Taxes [Line Items]
Deferred tax assets, net			$ 32,100
Northern States Financial Corporation
Income Taxes [Line Items]
Deferred tax assets, net	17,000
State and Local Jurisdiction
Income Taxes [Line Items]
Revaluation of deferred tax assets		2,800
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Revaluation of deferred tax assets	$ 8,700	$ 26,600

Income Taxes - Components of Ef

Income Taxes - Components of Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amount
Statutory federal income tax	$ 55,847	$ 41,382	$ 65,784
State income tax, net of federal income tax effect	14,172	8,846	5,069
Tax-exempt income, net of interest expense disallowance	(3,234)	(3,104)	(5,065)
Deferred tax asset revaluation	0	(8,721)	23,709
Other	(584)	784	70
Total income tax expense	$ 66,201	$ 39,187	$ 89,567
% of Pretax Income
Statutory federal income tax rate (percent of pretax income)	21.00%	21.00%	35.00%
State income tax, net of federal income tax effect (percent of pretax income)	5.30%	4.50%	2.70%
Tax-exempt income, net of interest expense disallowance (percent of pretax income)	(1.20%)	(1.60%)	(2.70%)
Deferred tax asset revaluation (percent of pretax income)	0.00%	(4.40%)	12.60%
Other (percent of pretax income)	(0.20%)	0.40%	0.10%
Effective tax rate	24.90%	19.90%	47.70%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Lease liability	$ 33,871
Allowance for credit losses	21,010	$ 19,591
Federal net operating loss ("NOL") carryforwards	19,505	8,871
Non-equity based compensation	7,115	2,210
Equity based compensation	5,043	3,971
OREO	1,996	1,460
Alternative minimum tax ("AMT") and other credit carryforwards	368	244
Deferred gain on sale-leaseback transaction		13,752
State NOL carryforwards		6,240
Deferred incentives		1,382
Property valuation adjustments		1,214
Other	6,988	5,232
Total deferred tax assets	95,896	64,167
Deferred tax liabilities:
Right-of-use asset	(29,611)
Accrued retirement benefits	(8,453)	(8,502)
Fixed assets	(5,648)	(7,322)
Deferred loan fees and costs	(5,445)	(4,985)
Acquisition adjustments	(1,261)	(686)
Other	(2,821)	(2,823)
Total deferred tax liabilities	(53,239)	(24,318)
Deferred tax valuation allowance	0	0
Net deferred tax assets	42,657	39,849
Tax effect of adjustments related to other comprehensive income (loss)	725	20,280
Net deferred tax assets including adjustments	43,382	60,129
NOL carryforwards available to offset future taxable income:
AMT credits	204	0
Internal Revenue Service (IRS)
NOL carryforwards available to offset future taxable income:
Gross NOL Carryforwards	92,880	42,242
ILLINOIS
NOL carryforwards available to offset future taxable income:
Gross NOL Carryforwards	0	209,802
INDIANA
NOL carryforwards available to offset future taxable income:
Gross NOL Carryforwards	0	14,260
WISCONSIN
NOL carryforwards available to offset future taxable income:
Gross NOL Carryforwards	$ 0	$ 1,212

Income Taxes - Rollforward of U

Income Taxes - Rollforward of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance		$ 16,350	$ 16,248	$ 2,039
Additions for tax positions relating to the current year		1,158	1,209	845
Additions for tax positions relating to prior years		0	582	13,389
Reductions for tax positions relating to prior years		(224)	(60)	(25)
Reductions for settlements with taxing authorities		(900)	(1,629)	0
Ending balance		16,384	16,350	16,248
Interest and penalties not included above:
Interest expense (income), net of tax effect, and penalties	[1]	38	(21)	118
Accrued interest and penalties, net of tax effect, at end of year	[1]	$ 208	$ 170	$ 191
[1]	Included in income tax expense in the Consolidated Statements of Income.

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan, employer matching contribution percent of employee's compensation	4.00%
Defined contribution plan, discretionary contribution vesting period	6 years
Actuarial losses as a percentage of accumulated benefit obligation	36.60%	50.40%
Pension Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Actuarial losses as a percentage of accumulated benefit obligation	10.00%
Contributions
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan, employee contribution limit, percentage of compensation	100.00%
Voluntary 401K Plans
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan, employer automatic contribution limit	2.00%
Deferred Profit Sharing
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan, employer automatic contribution limit	15.00%

Employee Benefit Plans - Profit

Employee Benefit Plans - Profit Sharing Plan (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan Disclosure [Line Items]
Profit sharing expense		$ 42,879	$ 43,104	$ 41,886
Profit Sharing Expense
Defined Contribution Plan Disclosure [Line Items]
Profit sharing expense	[1]	8,226	7,803	7,346
Company dividends received by the Profit Sharing Plan		$ 414	$ 457	$ 441
Company shares held by the Profit Sharing Plan at the end of the year:
Number of shares		812,886	1,047,213	1,079,975
Fair value		$ 18,745	$ 20,745	$ 25,930
[1]	Included in retirement and other employee benefits in the Consolidated Statements of Income.

Employee Benefit Plans - Pensio

Employee Benefit Plans - Pension Plan Cost and Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Accumulated benefit obligation	$ 70,236		$ 58,271
Change in projected benefit obligation
Beginning balance	58,271		67,923
Service cost	0		0
Interest cost	1,841		2,031	$ 1,712
Settlements	(4,268)		(7,199)
Actuarial loss (gain)	15,200		(3,717)
Benefits paid	(808)		(767)
Ending balance	70,236		58,271	67,923
Change in fair value of plan assets
Beginning balance	76,210		66,159
Actual return on plan assets	21,156		(6,983)
Benefits paid	(808)		(767)
Employer contributions	0		25,000
Settlements	(4,268)		(7,199)
Ending balance	92,290	[1]	76,210	$ 66,159
Funded status recognized in the Consolidated Statements of Financial Condition
Noncurrent asset	22,054		17,939
Amounts recognized in accumulated other comprehensive loss
Prior service cost	0		0
Net loss	25,721		29,345
Net amount recognized	$ 25,721		$ 29,345
Actuarial losses included in accumulated other comprehensive loss as a percent of
Accumulated benefit obligation	36.60%		50.40%
Fair value of plan assets	27.90%		38.50%
Amounts expected to be amortized from accumulated other comprehensive loss into net periodic benefit cost in the next fiscal year
Prior service cost	$ 0		$ 0
Net loss	820		426
Net amount expected to be recognized	$ 820		$ 426
Weighted-average assumptions at the end of the year used to determine the actuarial present value of the projected benefit obligation
Discount rate	3.04%		4.10%
[1]	Additional information regarding the fair value of Pension Plan assets as of December 31, 2019 can be found in Note 22, "Fair Value."

Employee Benefit Plans - Net Pe

Employee Benefit Plans - Net Periodic Benefit Pension Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of net periodic benefit cost
Interest cost	$ 1,841	$ 2,031	$ 1,712
Expected return on plan assets	(4,642)	(3,820)	(3,802)
Recognized net actuarial loss	531	533	591
Amortization of prior service cost	0	0	0
Recognized settlement loss	1,781	2,703	2,480
Net periodic (income) cost	(489)	1,447	981
Other changes in plan assets and benefit obligations recognized as a charge to other comprehensive income (loss)
Net gain (loss) for the period	1,313	(7,086)	(83)
Amortization of net loss	2,311	3,236	3,071
Total unrealized gain (loss)	3,624	(3,850)	2,988
Total recognized in net periodic pension cost and other comprehensive income (loss)	$ 4,113	$ (5,297)	$ 2,007
Weighted-average assumptions used to determine the net periodic cost
Discount rate	4.10%	3.45%	3.86%
Expected return on plan assets	5.75%	5.75%	6.25%

Employee Benefit Plans - Pens_2

Employee Benefit Plans - Pension Plan Asset Allocation (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Asset Category
Fair Value of Plan Assets (in dollars)		$ 92,290	[1]	$ 76,210	$ 66,159
Percentage of Plan Assets		100.00%		100.00%
Equity securities
Asset Category
Fair Value of Plan Assets (in dollars)	[1]	$ 54,800
Percentage of Plan Assets		59.00%		61.00%
Fixed income
Asset Category
Fair Value of Plan Assets (in dollars)	[1]	$ 33,976
Percentage of Plan Assets		37.00%		37.00%
Cash equivalents
Asset Category
Fair Value of Plan Assets (in dollars)	[1]	$ 3,514
Percentage of Plan Assets		4.00%		2.00%
Minimum | Equity securities
Asset Category
Target plan asset allocations		50.00%
Minimum | Fixed income
Asset Category
Target plan asset allocations		25.00%
Minimum | Cash equivalents
Asset Category
Target plan asset allocations		0.00%
Maximum | Equity securities
Asset Category
Target plan asset allocations		65.00%
Maximum | Fixed income
Asset Category
Target plan asset allocations		55.00%
Maximum | Cash equivalents
Asset Category
Target plan asset allocations		10.00%
[1]	Additional information regarding the fair value of Pension Plan assets as of December 31, 2019 can be found in Note 22, "Fair Value."

Employee Benefit Plans - Estima

Employee Benefit Plans - Estimated Future Pension Benefit Payments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Retirement Benefits [Abstract]
2020	$ 8,478
2021	5,300
2022	5,872
2023	4,497
2024	4,977
2025-2028	$ 20,844

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - shares	May 17, 2017	May 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, increase shares authorized (in shares)	100,000,000
2018 Stock and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, increase shares authorized (in shares)		2,000,000
Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			14,000	14,000
Restricted Stock And Restricted Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Granted (in shares)			497,000
Restricted Stock And Restricted Stock Unit Awards | Vesting After Two Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			50.00%
Restricted Stock And Restricted Stock Unit Awards | Vesting After Three Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			50.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of internal and external performance metric analysis			3 years
Metric weighting (percent)			50.00%
Granted (in shares)			146,000
Performance Shares | Vesting After Three Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			33.00%
Performance Shares | Vesting After Fourth Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			33.00%
Performance Shares | Vesting After Fifth Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			33.00%
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned of those granted based on performance			0.00%
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares earned of those granted based on performance			200.00%

Share-Based Compensation - Shar

Share-Based Compensation - Shares of Common Stock Available Under Share-Based Plans (Details)	Dec. 31, 2019shares
2018 Stock and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Authorized (in shares)	3,295,590	[1]
Shares Available For Grant (in shares)	2,648,229	[1]
Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Authorized (in shares)	481,250
Shares Available For Grant (in shares)	102,989
[1]	The shares of the Company's common stock underlying all outstanding equity awards governed by the Omnibus Plan that are canceled, forfeited, or expire will be available for issuance under the 2018 Stock and Incentive Plan.

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Award Transactions (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Restricted Stock/Unit Awards
Number of Shares/Units
Non-vested awards at beginning of year (in shares) | shares	947
Granted (in shares) | shares	497
Vested (in shares) | shares	(417)
Forfeited (in shares) | shares	(35)
Non-vested awards at end of year (in shares) | shares	992
Weighted Average Grant Date Fair Value
Non-vested awards at beginning of year (in dollars per share) | $ / shares	$ 23.32
Granted (in dollars per share) | $ / shares	23.04
Vested (in dollars per share) | $ / shares	21.13
Forfeited (in dollars per share) | $ / shares	24.20
Non-vested awards at end of year (in dollars per share) | $ / shares	$ 24.03
Performance Shares
Number of Shares/Units
Non-vested awards at beginning of year (in shares) | shares	468
Granted (in shares) | shares	146
Vested (in shares) | shares	(94)
Forfeited (in shares) | shares	(19)
Non-vested awards at end of year (in shares) | shares	501
Weighted Average Grant Date Fair Value
Non-vested awards at beginning of year (in dollars per share) | $ / shares	$ 19.88
Granted (in dollars per share) | $ / shares	23.04
Vested (in dollars per share) | $ / shares	21.13
Forfeited (in dollars per share) | $ / shares	24.20
Non-vested awards at end of year (in dollars per share) | $ / shares	$ 20.40

Share-Based Compensation - Othe

Share-Based Compensation - Other Restricted Stock Award/Unit Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit realized from the vesting/release of restricted stock, restricted stock unit, and performance share awards	$ 3,678	$ 3,365	$ 4,601
Restricted Stock Restricted Stock Unit and Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of restricted stock, restricted stock unit, and performance share awards granted during the year (in dollars per share)	$ 23.04	$ 24.96	$ 24.71
Total fair value of restricted stock, restricted stock unit, and performance share awards vested during the year	$ 13,092	$ 10,870	$ 13,760
Income tax benefit realized from the vesting/release of restricted stock, restricted stock unit, and performance share awards	$ 2,920	$ 2,970	$ 4,007

Share-Based Compensation - Effe

Share-Based Compensation - Effect of Recording Share-Based Compensation Expense (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Share-based compensation expense	[1]	$ 13,183	$ 12,062	$ 11,223
Income tax benefit		3,678	3,365	4,601
Share-based compensation expense, net of tax		9,505	8,697	6,622
Unrecognized compensation expense		$ 14,299	$ 13,982	$ 13,266
Weighted-average amortization period remaining (in years)		1 year 1 month 6 days	1 year 2 months 12 days	1 year 3 months 18 days
[1]	Comprised of restricted stock, restricted stock unit, and performance share awards expense.

Regulatory and Capital Matter_2

Regulatory and Capital Matters - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash reserve balance	$ 135.4	$ 149.2
Adjustment to available dividends	$ 91.4
Tier 1 risk based capital conservation buffer initial requirements phasing duration	4 years
January 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum ratio of CET1 to risk-weighted assets	4.50%
Capital conservation buffer	2.50%
Resulting minimum ratio of CET1 to risk-weighted assets after capital conversion buffer	7.00%
Minimum ratio of Tier 1 capital to risk-weighted assets	6.00%
Minimum ratio of Tier 1 capital to risk-weighted assets, adjusted	8.50%
Minimum ratio of Total capital to risk-weighted assets	8.00%
Minimum ratio of Total capital to risk-weighted assets, adjusted	10.50%
Minimum leverage ratio	4.00%

Regulatory and Capital Matter_3

Regulatory and Capital Matters - Summary of Capital Ratios (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
First Midwest Bancorp, Inc.
Total capital to risk-weighted assets:
Actual Capital	$ 1,843,597,000	$ 1,626,489,000
Actual Ratio (percent)	12.96%	12.62%
Adequately Capitalized Capital	$ 1,493,672,000	$ 1,273,103,000
Adequately Capitalized Ratio (percent)	10.50%	9.875%
Tier 1 capital to risk-weighted assets:
Actual Capital	$ 1,496,048,000	$ 1,315,098,000
Actual Ratio (percent)	10.52%	10.20%
Adequately Capitalized Capital	$ 1,209,163,000	$ 1,015,259,000
Adequately Capitalized Ratio (percent)	8.50%	7.875%
CET1 to risk-weighted assets:
Actual Capital	$ 1,496,048,000	$ 1,315,432,000
Actual Ratio (percent)	10.52%	10.20%
Adequately Capitalized Capital	$ 995,781,000	$ 821,876,000
Adequately Capitalized Ratio (percent)	7.00%	6.375%
Tier 1 capital to average assets:
Actual Capital	$ 1,496,048,000	$ 1,315,098,000
Actual Ratio (percent)	8.81%	8.90%
Adequately Capitalized Capital	$ 679,365,000	$ 591,293,000
Adequately Capitalized Ratio (percent)	4.00%	4.00%
First Midwest Bank
Total capital to risk-weighted assets:
Actual Capital	$ 1,598,886,000	$ 1,463,026,000
Actual Ratio (percent)	11.28%	11.39%
Adequately Capitalized Capital	$ 1,488,796,000	$ 1,268,662,000
Adequately Capitalized Ratio (percent)	10.50%	9.875%
To Be Well-Capitalized Under Prompt Corrective Action Provisions Capital	$ 1,417,901,000	$ 1,284,721,000
To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio (percent)	10.00%	10.00%
Tier 1 capital to risk-weighted assets:
Actual Capital	$ 1,489,664,000	$ 1,359,607,000
Actual Ratio (percent)	10.51%	10.58%
Adequately Capitalized Capital	$ 1,205,215,000	$ 1,011,718,000
Adequately Capitalized Ratio (percent)	8.50%	7.875%
To Be Well-Capitalized Under Prompt Corrective Action Provisions Capital	$ 1,134,320,000	$ 1,027,777,000
To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio (percent)	8.00%	8.00%
CET1 to risk-weighted assets:
Actual Capital	$ 1,489,664,000	$ 1,359,607,000
Actual Ratio (percent)	10.51%	10.58%
Adequately Capitalized Capital	$ 992,530,000	$ 819,009,000
Adequately Capitalized Ratio (percent)	7.00%	6.375%
To be Well-Capitalized Under Prompt Corrective Action Provisions Capital	$ 921,635,000	$ 835,068,000
To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio ( percent)	6.50%	6.50%
Tier 1 capital to average assets:
Actual Capital	$ 1,489,664,000	$ 1,359,607,000
Actual Ratio (percent)	8.79%	9.41%
Adequately Capitalized Capital	$ 677,570,000	$ 577,991,000
Adequately Capitalized Ratio (percent)	4.00%	4.00%
To Be Well-Capitalized Under Prompt Corrective Action Provisions Capital	$ 846,963,000	$ 722,488,000
To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio (percent)	5.00%	5.00%

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 02, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest rate cash flow hedge to be reclassified during next 12 months, net	$ (1,000)
Capital market products income	$ 13,931	$ 7,721	$ 8,171
Portion of fair value outstanding, interest rate swaps covered by collateral agreements (percent)	100.00%	100.00%
Cash Flow Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of variable rate loans hedged using interest rate swaps	$ 815,000
Amount hedged of borrowed funds using forward starting interest rate swaps	1,100,000			$ 560,000
Amount to be hedged of borrowed funds using forward staring interest rate swaps	$ 530,000
Weighted-average interest rate to be paid	2.13%

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Cash Flow Hedges (Details) - Cash Flow Hedging - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross notional amount outstanding		$ 1,905,000	$ 2,280,000
Derivative asset fair value in other assets	[1]	727	6,889
Derivative liability fair value in other liabilities	[1]	$ (119)	$ (11,328)
Weighted-average interest rate received (as a percent)		1.88%	2.12%
Weighted-average interest rate paid (as a percent)		1.74%	2.20%
Weighted-average maturity (in years)		1 year 2 months 4 days	1 year 6 months 10 days
[1]	Certain cash flow hedges are transacted through a clearinghouse ("centrally cleared") and their change in fair value is settled by the counterparties to the transaction, which results in no fair value.

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities - Other Derivative Instruments (Details) - Other Derivative Instruments - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Gross notional amount outstanding		$ 4,340,384	$ 3,085,226
Derivative asset fair value in other assets	[1]	61,709	25,168
Derivative liability fair value in other liabilities	[1]	(18,416)	(17,533)
Fair value of derivative	[2]	$ 18,856	$ 18,013
[1]	Certain other derivative instruments are centrally cleared and their change in fair value is settled by the counterparties to the transaction, which results in no fair value.
[2]	This amount represents the fair value if credit risk related contingent factors were triggered.

Derivative Instruments and He_6

Derivative Instruments and Hedging Activities - Cash Flow Hedge Accounting on AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Before tax	$ 4,670	$ 2,786
Interest Income
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Before tax	13,236	18,776	$ 11,150
Reclassification of gains (losses) included in net income	3,975	2,611	5,159
Interest Expense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Before tax	(16,873)	(20,500)	(8,025)
Reclassification of gains (losses) included in net income	$ (5,008)	$ (3,673)	$ (3,951)

Derivative Instruments and He_7

Derivative Instruments and Hedging Activities - Effect of Derivatives on Interest Income (Details) - Designated as Hedging Instrument - Cash Flow Hedging - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
(Loss) gain on derivative, net	$ (1,033)	$ (1,062)	$ 1,208
Interest Income
Derivative Instruments and Hedging Activities Disclosures [Line Items]
(Loss) gain on derivative, net	3,975	2,611	5,159
Interest Expense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
(Loss) gain on derivative, net	$ (5,008)	$ (3,673)	$ (3,951)

Derivative Instruments and He_8

Derivative Instruments and Hedging Activities - Offsetting Derivatives (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Assets
Gross amounts recognized		$ 62,436	$ 32,057
Less: amounts offset in the Consolidated Statements of Financial Condition		0	0
Net amount presented in the Consolidated Statements of Financial Condition	[1]	62,436	32,057
Offsetting derivative positions		(2,674)	(11,678)
Cash collateral pledged		0	(9,060)
Net credit exposure		59,762	11,319
Liabilities
Gross amounts recognized		18,535	28,861
Less: amounts offset in the Consolidated Statements of Financial Condition		0	0
Net amount presented in the Consolidated Statements of Financial Condition	[1]	18,535	28,861
Offsetting derivative positions		(2,674)	(11,678)
Cash collateral pledged		(15,861)	(3,506)
Net credit exposure		$ 0	$ 13,677
[1]	Included in other assets or other liabilities in the Consolidated Statements of Financial Condition.

Commitments, Guarantees, and _3

Commitments, Guarantees, and Contingent Liabilities (Details) - Contractual or Notional Amounts of Financial Instruments - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Commitments to extend credit:
Letters of credit		$ 103,684	$ 112,728
Commitments to extend credit
Commitments to extend credit:
Commercial, industrial, and agricultural		1,852,040	1,729,286
Commercial real estate		296,053	296,882
Home equity		576,956	570,553
Other commitments	[1]	251,093	244,917
Total commitments to extend credit		$ 2,976,142	$ 2,841,638
[1]	Other commitments includes installment and overdraft protection program commitments.

Fair Value - Recurring Fair Val

Fair Value - Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017	[1]	Dec. 31, 2016
Assets
Equity securities, at fair value		$ 42,136		$ 30,806
Securities available-for-sale:
Securities available-for-sale, at fair value		2,873,386		2,272,009
Mortgage servicing rights (MSRs)		5,858	[1]	6,730	[1]	$ 5,894		$ 6,120
U.S. treasury securities
Securities available-for-sale:
Securities available-for-sale, at fair value		34,075		37,767
U.S. agency securities
Securities available-for-sale:
Securities available-for-sale, at fair value		248,424		142,563
CMOs
Securities available-for-sale:
Securities available-for-sale, at fair value		1,557,671		1,315,209
MBSs
Securities available-for-sale:
Securities available-for-sale, at fair value		684,684		466,934
Municipal securities
Securities available-for-sale:
Securities available-for-sale, at fair value		234,431		227,187
Corporate debt securities
Securities available-for-sale:
Securities available-for-sale, at fair value		114,101		82,349
Recurring | Level 1
Assets
Equity securities, at fair value		23,703		19,658
Securities available-for-sale:
Securities available-for-sale, at fair value		34,075		37,767
Mortgage servicing rights (MSRs)		0		0	[2]
Derivative assets	[2]	0		0
Liabilities
Derivative liabilities	[3]	0		0
Recurring | Level 1 | U.S. treasury securities
Securities available-for-sale:
Securities available-for-sale, at fair value		34,075		37,767
Recurring | Level 1 | U.S. agency securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 1 | CMOs
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 1 | MBSs
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 1 | Municipal securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 1 | Corporate debt securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 2
Assets
Equity securities, at fair value		13,400		11,148
Securities available-for-sale:
Securities available-for-sale, at fair value		2,839,311		2,234,242
Mortgage servicing rights (MSRs)	[2]	0		0
Derivative assets	[2]	62,436		32,057
Liabilities
Derivative liabilities	[3]	18,535		28,861
Recurring | Level 2 | U.S. treasury securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 2 | U.S. agency securities
Securities available-for-sale:
Securities available-for-sale, at fair value		248,424		142,563
Recurring | Level 2 | CMOs
Securities available-for-sale:
Securities available-for-sale, at fair value		1,557,671		1,315,209
Recurring | Level 2 | MBSs
Securities available-for-sale:
Securities available-for-sale, at fair value		684,684		466,934
Recurring | Level 2 | Municipal securities
Securities available-for-sale:
Securities available-for-sale, at fair value		234,431		227,187
Recurring | Level 2 | Corporate debt securities
Securities available-for-sale:
Securities available-for-sale, at fair value		114,101		82,349
Recurring | Level 3
Assets
Equity securities, at fair value		0		0
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Mortgage servicing rights (MSRs)	[2]	5,858		6,730
Derivative assets	[2]	0		0
Liabilities
Derivative liabilities	[3]	0		0
Recurring | Level 3 | U.S. treasury securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 3 | U.S. agency securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 3 | CMOs
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 3 | MBSs
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 3 | Municipal securities
Securities available-for-sale:
Securities available-for-sale, at fair value		0		0
Recurring | Level 3 | Corporate debt securities
Securities available-for-sale:
Securities available-for-sale, at fair value		$ 0		$ 0
[1]	Included in other assets in the Consolidated Statements of Financial Condition.
[2]	Included in other assets in the Consolidated Statements of Financial Condition.
[3]	Included in other liabilities in the Consolidated Statements of Financial Condition.

Fair Value - Narrative (Details

Fair Value - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value [Line Items]
Equity securities, at fair value	$ 42,136	$ 30,806
Total amount of loans being serviced for the benefit of others at the end of the year	$ 653,656	627,323	$ 607,016
Minimum
Fair Value [Line Items]
Appraisal adjustment (percent)	0.00%
Maximum
Fair Value [Line Items]
Appraisal adjustment (percent)	15.00%
Recurring | Level 2
Fair Value [Line Items]
Equity securities, at fair value	$ 13,400	$ 11,148
Recurring | Level 2 | Community Development Investments
Fair Value [Line Items]
Equity securities, at fair value	$ 5,000

Fair Value - Rollforward of Car

Fair Value - Rollforward of Carrying Value of CDOs (Details) - CDOs $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Rollforward of the Carrying Value of CDOs
Beginning balance	$ 33,260
Additions	0
Change in other comprehensive income	14,421	[1]
Paydowns and sales	(47,681)
Ending balance	$ 0
[1]	Included in unrealized holding gains (losses) in the Consolidated Statements of Comprehensive Income.

Fair Value - Significant Unobse

Fair Value - Significant Unobservable Inputs Used in the Valuation of MSRs (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Minimum
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Prepayment speed	6.70%	6.50%
Maturity (months)	18 months	20 months
Discount rate	9.30%	9.50%
Maximum
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Prepayment speed	12.00%	13.50%
Maturity (months)	94 months	104 months
Discount rate	12.00%	12.00%

Fair Value - Rollforward of C_2

Fair Value - Rollforward of Carrying Value of MSRs (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Rollforward of Carrying Value of MSRs
Beginning balance		$ 6,730	[1]	$ 5,894	[1]	$ 6,120
New MSRs		1,228		1,080		673
Total (losses) gains included in earnings:
Changes in valuation inputs and assumptions	[2]	(1,559)		475		(41)
Other changes in fair value	[2],[3]	(541)		(719)		(858)
Ending balance	[1]	5,858		6,730		5,894
Contractual servicing fees earned during the year	[2]	1,586		1,517		1,536
Total amount of loans being serviced for the benefit of others at the end of the year		$ 653,656		$ 627,323		$ 607,016
[1]	Included in other assets in the Consolidated Statements of Financial Condition.
[2]	Included in mortgage banking income in the Consolidated Statements of Income and related to assets held as of December 31, 2019, 2018, and 2017.
[3]	Primarily represents changes in expected future cash flows over time due to payoffs and paydowns.

Fair Value - Annual Fair Value

Fair Value - Annual Fair Value Measurements of Pension Plan Asses (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		$ 92,290	[1]	$ 76,210	$ 66,159
Mutual funds
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	[2]	34,231		27,246
U.S. agency securities
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		7,405		8,015
Corporate debt securities
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		10,865		10,472
Common stocks
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		34,693		26,882
Common trust fund
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		5,096		3,595
Level 1
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		72,644		58,517
Level 1 | Mutual funds
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	[2]	34,231		27,246
Level 1 | U.S. agency securities
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		3,720		4,389
Level 1 | Corporate debt securities
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		0		0
Level 1 | Common stocks
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		34,693		26,882
Level 2
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		14,550		14,098
Level 2 | Mutual funds
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets	[2]	0		0
Level 2 | U.S. agency securities
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		3,685		3,626
Level 2 | Corporate debt securities
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		10,865		10,472
Level 2 | Common stocks
Fair Value Defined Benefit Plan Disclosure [Line Items]
Pension plan assets		$ 0		$ 0
[1]	Additional information regarding the fair value of Pension Plan assets as of December 31, 2019 can be found in Note 22, "Fair Value."
[2]	Includes mutual funds, money market funds, cash, cash equivalents, and accrued interest.

Fair Value - Non-Recurring Fair

Fair Value - Non-Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Fair Value (Details) - Assets Measured On A Non-Recurring Basis [Line Items]
OREO		$ 8,750	$ 12,821
Level 1 | Nonrecurring
Fair Value (Details) - Assets Measured On A Non-Recurring Basis [Line Items]
Collateral-dependent impaired loans	[1]	0	0
OREO	[2]	0	0
Loans held-for-sale	[3]	0	0
Assets held-for-sale	[4]	0	0
Level 2 | Nonrecurring
Fair Value (Details) - Assets Measured On A Non-Recurring Basis [Line Items]
Collateral-dependent impaired loans	[1]	0	0
OREO	[2]	0	0
Loans held-for-sale	[3]	0	0
Assets held-for-sale	[4]	0	0
Level 3 | Nonrecurring
Fair Value (Details) - Assets Measured On A Non-Recurring Basis [Line Items]
Collateral-dependent impaired loans	[1]	41,326	24,565
OREO	[2]	3,325	6,012
Loans held-for-sale	[3]	36,032	3,478
Assets held-for-sale	[4]	$ 6,824	$ 3,722
[1]	Includes impaired loans with charge-offs and impaired loans with a specific reserve during the periods presented.
[2]	Includes OREO with fair value adjustments subsequent to initial transfer that occurred during the periods presented.
[3]	Included in other assets in the Consolidated Statements of Financial Condition.
[4]	Included in premises, furniture, and equipment in the Consolidated Statements of Financial Condition.

Fair Value - Fair Value Measure

Fair Value - Fair Value Measurements of Other Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 214,894	$ 211,189
Interest-bearing deposits in other banks	84,327	78,069
Securities held-to-maturity	21,997	10,176
FHLB and FRB stock	115,409	80,302
Loans	12,732,308	11,344,564
Investment in BOLI	296,351	296,733
Liabilities
Deposits	13,251,278	12,084,112
Borrowed funds	1,658,758	906,079
Senior and subordinated debt	233,948	203,808
Level 1 | Carrying Amount
Assets
Cash and due from banks	214,894	211,189
Level 1 | Fair Value
Assets
Cash and due from banks	214,894	211,189
Level 2 | Carrying Amount
Assets
Interest-bearing deposits in other banks	84,327	78,069
Securities held-to-maturity	21,997	10,176
FHLB and FRB stock	115,409	80,302
Liabilities
Deposits	13,251,278	12,084,112
Borrowed funds	1,658,758	906,079
Senior and subordinated debt	233,948	203,808
Accrued interest payable	10,502	10,005
Level 2 | Fair Value
Assets
Interest-bearing deposits in other banks	84,327	78,069
Securities held-to-maturity	21,234	9,871
FHLB and FRB stock	115,409	80,302
Liabilities
Deposits	13,247,871	12,064,604
Borrowed funds	1,658,758	906,079
Senior and subordinated debt	277,203	211,207
Accrued interest payable	10,502	10,005
Level 3 | Carrying Amount
Assets
Loans	12,733,200	11,346,668
Investment in BOLI	296,351	296,733
Accrued interest receivable	59,716	54,847
Other interest-earning assets	0	5
Level 3 | Fair Value
Assets
Loans	12,535,848	11,052,040
Investment in BOLI	296,351	296,733
Accrued interest receivable	59,716	54,847
Other interest-earning assets	$ 0	$ 5

Related Party Transactions - Na

Related Party Transactions - Narrative (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (percent)	5.00%	5.00%

Condensed Parent Company Fina_3

Condensed Parent Company Financial Statements - Statements of Financial Condition (Parent Company Only) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 214,894	$ 211,189
Other assets	437,581	245,734
Total assets	17,850,397	15,505,649
Liabilities and Stockholders' Equity
Senior and subordinated debt	233,948	203,808
Accrued interest payable and other liabilities	335,620	256,652
Stockholders' equity	2,370,793	2,054,998	$ 1,864,874	$ 1,257,080
Total liabilities and stockholders' equity	17,850,397	15,505,649
Parent Company
Assets
Cash and due from banks	247,507	158,026
Investments in and advances to subsidiaries	2,360,467	2,091,158
Other assets	45,306	55,782
Total assets	2,653,280	2,304,966
Liabilities and Stockholders' Equity
Senior and subordinated debt	233,948	203,808
Accrued interest payable and other liabilities	48,539	46,160
Stockholders' equity	2,370,793	2,054,998
Total liabilities and stockholders' equity	$ 2,653,280	$ 2,304,966

Condensed Parent Company Fina_4

Condensed Parent Company Financial Statements - Statements of Income (Parent Company Only) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income
Interest income	$ 698,739	$ 582,492	$ 509,716
Securities transactions and other	11,586	9,636	9,859
Expenses
Interest expense	110,257	65,870	37,712
Other expenses	28,995	28,236	23,956
Income before income tax expense	265,939	197,057	187,954
Income tax benefit	(66,201)	(39,187)	(89,567)
Net income	199,738	157,870	98,387
Net income applicable to non-vested restricted shares	(1,681)	(1,312)	(916)
Net income applicable to common shares	198,057	156,558	97,471
Parent Company
Income
Dividends from subsidiaries	236,137	86,095	74,091
Interest income	613	453	2,211
Securities transactions and other	23	280	(1,372)
Total income	236,773	86,828	74,930
Expenses
Interest expense	14,431	12,708	12,428
Salaries and employee benefits	13,903	22,430	20,978
Other expenses	11,384	9,440	9,126
Total expenses	39,718	44,578	42,532
Income before income tax expense	197,055	42,250	32,398
Income tax benefit	10,609	13,299	14,851
Income before equity in undistributed income of subsidiaries	207,664	55,549	47,249
Equity in undistributed (loss) income of subsidiaries	(7,926)	102,321	51,138
Net income	199,738	157,870	98,387
Net income applicable to non-vested restricted shares	(1,681)	(1,312)	(916)
Net income applicable to common shares	$ 198,057	$ 156,558	$ 97,471

Condensed Parent Company Fina_5

Condensed Parent Company Financial Statements - Statements of Cash Flows (Parent Company Only) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income		$ 199,738	$ 157,870	$ 98,387
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of premises, furniture, and equipment		16,366	15,865	13,995
Net securities losses		0	0
Net securities losses				1,876
Share-based compensation expense	[1]	13,183	12,062	11,223
Tax benefit related to share-based compensation		364	258	349
Net (increase) decrease in other assets		(146,968)	(44,246)	121,577
Net increase (decrease) in other liabilities		108,956	(4,346)	(56,055)
Net cash provided by operating activities		227,109	253,184	234,266
Investing Activities
Purchases of premises, furniture, and equipment		(20,330)	(27,800)	(16,123)
Net cash (paid) received for acquisitions		13,532
Net cash used in investing activities		(1,054,193)	(1,002,386)	(145,780)
Financing Activities
Repurchases of common stock		(33,928)	0	0
Cash dividends paid		(56,540)	(44,293)	(37,129)
Restricted stock activity		(3,830)	(4,421)	(3,659)
Net cash used in financing activities		837,047	691,890	(4,064)
Supplemental Disclosures of Cash Flow Information:
Common stock issued for acquisitions, net of issuance costs		101,496	83,303	534,090
Parent Company
Operating Activities
Net income		199,738	157,870	98,387
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed loss (income) of subsidiaries		7,926	(102,321)	(51,138)
Depreciation of premises, furniture, and equipment		51	42	9
Net securities losses		0	0
Net securities losses				1,523
Share-based compensation expense		13,183	12,062	11,223
Tax benefit related to share-based compensation		364	258	349
Net (increase) decrease in other assets		(67,330)	35,981	18,667
Net increase (decrease) in other liabilities		49,813	(17,942)	(52,377)
Net cash provided by operating activities		203,745	85,950	26,643
Investing Activities
Proceeds from sales and maturities of securities available-for-sale		0	0	42,516
Purchases of premises, furniture, and equipment		0	(61)	(119)
Net cash (paid) received for acquisitions		(19,966)	39	(47,364)
Net cash used in investing activities		(19,966)	(22)	(4,967)
Financing Activities
Repurchases of common stock		(33,928)
Cash dividends paid		(56,540)	(44,293)	(37,129)
Restricted stock activity		(3,830)	(4,421)	(3,952)
Net cash used in financing activities		(94,298)	(48,714)	(41,081)
Cash and Cash Equivalents, Period Increase (Decrease), Total		89,481	37,214	(19,405)
Cash and Cash Equivalents, at Carrying Value, Beginning Balance		158,026	120,812	140,217
Cash and Cash Equivalents, at Carrying Value, Ending Balance		247,507	158,026	120,812
Supplemental Disclosures of Cash Flow Information:
Common stock issued for acquisitions, net of issuance costs		$ 101,496	$ 83,303	$ 534,090
[1]	Comprised of restricted stock, restricted stock unit, and performance share awards expense.