First Midwest Bancorp (ONBPP) 10-Q 6 Nov 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Nov. 03, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	FIRST MIDWEST BANCORP INC
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		102,728,899
Amendment Flag	false
Entity Central Index Key	702,325
Entity Filer Category	Large Accelerated Filer
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3

Consolidated Statements of Fina

Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 174,147	$ 155,055
Interest-bearing deposits in other banks	252,753	107,093
Trading securities, at fair value	20,425	17,920
Securities available-for-sale, at fair value	1,732,984	1,919,450
Securities held-to-maturity, at amortized cost	14,638	22,291
Federal Home Loan Bank (FHLB) and Federal Reserve Bank (FRB) stock, at cost	69,708	59,131
Loans	10,390,292	8,254,145
Allowance for loan losses	(94,814)	(86,083)
Net loans	10,295,478	8,168,062
Other real estate owned (OREO)	19,873	26,083
Premises, furniture, and equipment, net	131,295	82,577
Investment in bank-owned life insurance (BOLI)	279,639	219,746
Goodwill and other intangible assets	750,436	366,876
Accrued interest receivable and other assets	525,766	278,271
Total assets	14,267,142	11,422,555
Liabilities
Noninterest-bearing deposits	3,580,922	2,766,748
Interest-bearing deposits	7,627,575	6,061,855
Total deposits	11,208,497	8,828,603
Borrowed funds	700,536	879,008
Senior and subordinated debt	195,028	194,603
Accrued interest payable and other liabilities	297,951	263,261
Total liabilities	12,402,012	10,165,475
Stockholders' Equity
Common stock	1,123	913
Additional paid-in capital	1,029,002	498,937
Retained earnings	1,082,921	1,016,674
Accumulated other comprehensive loss, net of tax	(38,036)	(40,910)
Treasury stock, at cost	(209,880)	(218,534)
Total stockholders' equity	1,865,130	1,257,080
Total liabilities and stockholders' equity	$ 14,267,142	$ 11,422,555
Stockholders' Equity, Number of Shares, Par Value, and Other Disclosures
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares authorized (in shares)	250,000,000	150,000,000
Common stock, shares issued (in shares)	112,348,000	91,284,000
Common stock, shares outstanding (in shares)	102,722,000	81,325,000
Treasury stock, shares (in shares)	9,626,000	9,959,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest Income
Loans	$ 118,101	$ 87,505	$ 345,286	$ 252,486
Investment securities	10,667	9,629	31,678	27,550
Other short-term investments	1,148	772	3,167	1,968
Total interest income	129,916	97,906	380,131	282,004
Interest Expense
Deposits	4,369	2,520	11,307	7,387
Borrowed funds	2,544	1,782	6,837	4,597
Senior and subordinated debt	3,110	2,632	9,314	8,353
Total interest expense	10,023	6,934	27,458	20,337
Net interest income	119,893	90,972	352,673	261,667
Provision for loan losses	10,109	9,998	23,266	25,676
Net interest income after provision for loan losses	109,784	80,974	329,407	235,991
Noninterest Income
Service charges on deposit accounts	12,561	10,708	36,079	30,350
Wealth management fees	10,169	8,495	30,354	24,696
Card-based fees	5,992	7,332	22,940	21,642
Capital market products income	2,592	2,916	6,185	8,197
Mortgage banking income	2,246	3,394	5,779	6,625
Other service charges, commissions, and fees	4,745	5,621	16,043	16,484
Net gain on sale-leaseback transaction	0	5,509	0	5,509
Net securities gains	3,197	187	3,481	1,097
Other income	1,846	1,691	7,383	5,001
Total noninterest income	43,348	45,853	128,244	119,601
Noninterest Expense
Salaries and employee benefits	55,638	46,372	165,985	137,233
Net occupancy and equipment expense	12,115	10,755	36,925	30,380
Professional services	8,498	6,772	26,073	17,984
Technology and related costs	4,505	3,881	13,423	11,251
Net OREO expense	657	313	3,988	2,099
Other expenses	15,393	13,623	47,066	41,074
Acquisition and integration related expenses	384	1,172	20,123	6,810
Total noninterest expense	97,190	82,888	313,583	246,831
Income before income tax expense	55,942	43,939	144,068	108,761
Income tax expense	17,707	15,537	48,028	37,130
Net income	$ 38,235	$ 28,402	$ 96,040	$ 71,631
Per Common Share Data
Basic earnings per common share (in dollars per share)	$ 0.37	$ 0.35	$ 0.94	$ 0.89
Diluted earnings per common share (in dollars per share)	0.37	0.35	0.94	0.89
Dividends declared per common share (in dollars per share)	$ 0.10	$ 0.09	$ 0.29	$ 0.27
Weighted-average common shares outstanding (in Shares)	101,752	80,396	101,307	79,589
Weighted-average diluted common shares outstanding (in Shares)	101,772	80,409	101,327	79,602

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 38,235	$ 28,402	$ 96,040	$ 71,631
Unrealized holding gains (losses):
Before tax	428	(6,695)	11,078	21,671
Tax effect	(174)	2,676	(4,436)	(8,665)
Net of tax	254	(4,019)	6,642	13,006
Reclassification of net gains included in net income:
Before tax	3,197	187	3,481	1,097
Tax effect	(1,311)	(75)	(1,425)	(439)
Net of tax	1,886	112	2,056	658
Net unrealized holding (losses) gains	(1,632)	(4,131)	4,586	12,348
Derivative Instruments
Before tax	276	(779)	(2,849)	4,420
Tax effect	(113)	311	1,137	(1,781)
Net of tax	163	(468)	(1,712)	2,639
Total other comprehensive (loss) income	(1,469)	(4,599)	2,874	14,987
Total comprehensive income	$ 36,766	$ 23,803	$ 98,914	$ 86,618

Consolidated Statements of Com5

Consolidated Statements of Comprehensive Income - AOCI - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income	$ 2,874	$ 14,987
Accumulated Unrealized Gain (Loss) on Securities Available- for-Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(22,645)	(10,271)
Other comprehensive income	4,586	12,348
Ending balance	(18,059)	2,077
Accumulated Unrealized Gain (Loss) on Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,176)	(2,468)
Other comprehensive income	(1,712)	2,639
Ending balance	(2,888)	171
Unrecognized Net Pension Costs
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(17,089)	(15,650)
Other comprehensive income	0	0
Ending balance	(17,089)	(15,650)
Total Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(40,910)	(28,389)
Other comprehensive income	2,874	14,987
Ending balance	$ (38,036)	$ (13,402)

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
Balance Beginning (in Shares) at Dec. 31, 2015		77,952
Balance Beginning at Dec. 31, 2015	$ 1,146,268	$ 882	$ 446,672	$ 953,516	$ (28,389)	$ (226,413)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	71,631			71,631
Other comprehensive income	14,987				14,987
Common dividends declared ($0.27 and $0.29 per common share in 2016 and 2017, respectively)	(21,876)			(21,876)
Acquisitions, net of issuance costs (in Shares)		3,042
Acquisitions, net of issuance costs	54,896	$ 31	54,865
Common stock issued (in Shares)		10
Common stock issued	169		169
Restricted stock activity (in Shares)		326
Restricted stock activity	(2,548)		(10,610)			8,062
Treasury stock issued to benefit plans (in Shares)		(6)
Treasury stock issued to benefit plans	(106)		(21)			(85)
Share-based compensation expense	5,843		5,843
Balance Ending at Sep. 30, 2016	$ 1,269,264	$ 913	496,918	1,003,271	(13,402)	(218,436)
Balance Ending (in Shares) at Sep. 30, 2016		81,324
Balance Beginning (in Shares) at Dec. 31, 2016	81,325	81,325
Balance Beginning 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	96,040			96,040
Other comprehensive income	2,874				2,874
Common dividends declared ($0.27 and $0.29 per common share in 2016 and 2017, respectively)	(29,793)			(29,793)
Acquisitions, net of issuance costs (in Shares)		21,078
Acquisitions, net of issuance costs	534,090	$ 210	533,322			558
Common stock issued (in Shares)		7
Common stock issued	175		175
Restricted stock activity (in Shares)		321
Restricted stock activity	(3,679)		(11,987)			8,308
Treasury stock issued to benefit plans (in Shares)		(9)
Treasury stock issued to benefit plans	(211)		1			(212)
Share-based compensation expense	8,554		8,554
Balance Ending at Sep. 30, 2017	$ 1,865,130	$ 1,123	$ 1,029,002	$ 1,082,921	$ (38,036)	$ (209,880)
Balance Ending (in Shares) at Sep. 30, 2017	102,722	102,722

Consolidated Statements of Cha7

Consolidated Statements of Changes In Stockholders' Equity (Parentheticals) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.10	$ 0.09	$ 0.29	$ 0.27

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Statement of Cash Flows [Abstract]
Net cash (used in) provided by operating activities	$ (50,073)	$ 104,626
Investing Activities
Proceeds from maturities, repayments, and calls of securities available-for-sale	251,160	263,243
Proceeds from sales of securities available-for-sale	437,401	42,794
Purchases of securities available-for-sale	(289,244)	(824,883)
Proceeds from maturities, repayments, and calls of securities held-to-maturity	7,663	4,695
Purchases of securities held-to-maturity	(10)	(16)
Net purchases of FHLB stock	(7,330)	(12,651)
Net increase in loans	(392,384)	(630,012)
Premiums paid on BOLI, net of proceeds from claims	132	1,597
Proceeds from sales of OREO	17,460	6,069
Proceeds from sales of premises, furniture, and equipment	13,135	150,747
Purchases of premises, furniture, and equipment	(11,680)	(12,320)
Net cash received from acquisitions	41,717	57,347
Net cash provided by (used in) investing activities	68,020	(953,390)
Financing Activities
Net increase in deposit accounts	356,020	413,445
Net (decrease) increase in borrowed funds	(178,472)	472,027
Net proceeds from the issuance of subordinated notes	0	146,484
Payments for the maturity of subordinated debt	0	(38,500)
Cash dividends paid	(26,852)	(21,885)
Restricted stock activity	(3,891)	(2,318)
Net cash provided by financing activities	146,805	969,253
Net increase in cash and cash equivalents	164,752	120,489
Cash and cash equivalents at beginning of period	262,148	381,202
Cash and cash equivalents at end of period	426,900	501,691
Supplemental Disclosures of Cash Flow Information:
Income taxes paid	14,310	14,645
Interest paid to depositors and creditors	27,538	17,656
Dividends declared, but unpaid	10,184	7,241
Stock issued for acquisitions, net of issuance costs	534,090	54,896
Non-cash transfers of loans to OREO	3,770	3,894
Non-cash transfers of loans held-for-investment to loans held-for-sale	$ 42,970	$ 77,030

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation – The accompanying unaudited condensed consolidated interim financial statements ("consolidated financial statements") of First Midwest Bancorp, Inc. (the " Company "), a Delaware corporation, were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (" SEC ") for quarterly reports on Form 10-Q and reflect all adjustments that management deems necessary for the fair presentation of the financial position and results of operations for the periods presented. The results of operations for the quarter and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 . 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. The accompanying consolidated financial statements do not include certain information and note disclosures required by GAAP for complete annual financial statements. Therefore, these financial statements should be read in conjunction with the Company 's 2016 Annual Report on Form 10-K (" 2016 10-K"). The Company uses the accrual basis of accounting for financial reporting purposes. 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. The accounting policies related to business combinations, loans, the allowance for credit losses, and derivative financial instruments are presented below. For a summary of all other significant accounting policies, see Note 1, "Summary of Significant Accounting Policies," in the Company 's 2016 10-K. 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 Condensed Consolidated Statements of Income from the effective date of the acquisition. 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 consists 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. 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, automobile, 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 ( " TDR s" ) – 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 TDR s when the modification is short-term or results in an insignificant delay in payments. The Company 's TDR s 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 TDR s 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 restructured until it is paid in full or charged-off. Impaired Loans – Impaired loans consist of corporate non-accrual loans and TDR s. 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 TDR s, 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 probability of default/loss given default (" 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 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, the economy, changes in interest rates and property values, and the interpretation of loan risk classifications by regulatory authorities. 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.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Adopted Accounting Pronouncements Contingent Put and Call Options in Debt Instruments: In March of 2016, the Financial Accounting Standards Board ("FASB") issued final guidance clarifying the requirements for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. Entities are required to apply the guidance to existing debt instruments (or hybrid financial instruments that are determined to have a debt host) using a modified retrospective transition method as of the period of adoption. The adoption of this guidance on January 1, 2017 did not impact the Company 's financial condition, results of operations, or liquidity. Equity Method Accounting: In March of 2016, the FASB issued final guidance to simplify the equity method of accounting. The guidance eliminates the requirement to retrospectively apply equity method accounting in previous periods when an investor initially obtains significant influence over an investee. This guidance is effective for annual and interim periods beginning after December 15, 2016. The adoption of this guidance on January 1, 2017 did not impact the Company 's financial condition, results of operations, or liquidity. Accounting for Employee Share-based Payments: In March of 2016, the FASB issued guidance to simplify the accounting for employee share-based payment transactions. The guidance requires entities to recognize the income tax effects of awards in the income statement when the awards vest or are settled. In addition, the guidance allows entities to repurchase more of an employee's shares than it can under current guidance for tax withholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur. The adoption of this guidance on January 1, 2017 resulted in a $638,000 tax benefit to the provision for income tax expense for the nine months ended September 30, 2017 , recorded in the Company's results of operations. The Company elected to estimate forfeitures, which is consistent with the Company's practice before the adoption of this guidance. Accounting Pronouncements Pending Adoption Revenue from Contracts with Customers: In May of 2014, the FASB issued guidance that requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In March of 2016, the FASB issued an amendment to this guidance to clarify the implementation of guidance on principal versus agent consideration. Additional amendments to clarify the implementation guidance on the identification of performance obligations and licensing were issued in April of 2016 and narrow-scope improvements and practical expedients were issued in May of 2016. The guidance was initially effective for annual and interim reporting periods beginning on or after December 15, 2016 but was deferred to December 15, 2017, and must be applied either retrospectively or using the modified retrospective approach. Early adoption is permitted, but not before the original effective date. The Company's revenue is comprised of net interest income on financial assets and liabilities, which is excluded from the scope of this guidance, and noninterest income. The primary sources of revenue within noninterest income are service charges on deposit accounts, wealth management fees, card-based fees, and merchant servicing fees. Based upon the Company's initial assessment, this guidance is expected to affect how the Company currently presents certain contract costs on a gross basis versus a net basis against the related noninterest income and will result in the expansion of the qualitative disclosures regarding noninterest income. The Company will adopt this guidance on January 1, 2018 using the modified retrospective approach and does not expect the changes in presentation of certain contract costs or the expanded disclosures to have a significant impact on the Company's financial condition, results of operations, or liquidity. The Company is in the process of completing its review of contracts to validate this initial assessment. Amendments to Guidance on Classifying and Measuring Financial Instruments: In January of 2016, the FASB issued guidance that will require entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value. Any changes in fair value will be recognized in net income unless the investments qualify for a new practicability exception. This guidance also requires entities to adjust the fair value disclosures for financial instruments carried at amortized cost from an entry price to an exit price. No changes were made to the guidance for classifying and measuring investments in debt securities and loans. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Leases: In February of 2016, the FASB issued guidance 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. Early adoption is permitted. During 2016, First Midwest Bank (the "Bank") entered into a sale-leaseback transaction that resulted in a deferred gain of $82.5 million , with $76.1 million remaining as of September 30, 2017 . Upon adoption of this guidance, the remaining deferred gain will be recognized immediately as a cumulative-effect adjustment to equity. For additional discussion of the sale-leaseback transaction, see Note 8 " Premises, Furniture, and Equipment ." Management is evaluating the new guidance and the additional impact to the Company 's financial condition, results of operations, or liquidity. Measurement of Credit Losses on Financial Instruments: In June of 2016, the FASB issued guidance 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. Management is evaluating the new guidance and the impact to the Company 's financial condition, results of operations, and liquidity. Classification of Certain Cash Receipts and Cash Payments: In August of 2016, the FASB issued guidance clarifying certain cash flow presentation and classification issues to reduce diversity in practice. This guidance is effective for annual and interim reporting periods beginning on or after December 15, 2017. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company 's Consolidated Statement of Cash Flows. Income Taxes: In October of 2016, the FASB issued guidance that requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Clarifying the Definition of a Business: In January of 2017, the FASB issued guidance that clarifies the definition of a business to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Accounting for Goodwill Impairment: In January of 2017, the FASB issued guidance 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. Presentation of Defined Benefit Retirement Plan Costs: In March of 2017, the FASB issued guidance that changes how employers that sponsor defined pension and or other postretirement benefit plans present the net periodic benefit cost in the income statement. Employers will present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Other components of net periodic benefit cost will be presented separately from the line item(s) that includes the service cost. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Premium Amortization on Purchased Callable Debt Securities: In March of 2017, the FASB issued guidance 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. 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. Share-based Payment Award Modifications: In May of 2017, the FASB issued guidance to reduce diversity in practice by clarifying when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Derivatives and Hedging: In August of 2017, the FASB issued guidance to better align the financial reporting related to hedging activities with the economic objectives of those activities and to simplify the application of current hedge accounting guidance. Entities are required to apply the guidance using a modified retrospective method as of the period of adoption. This guidance is effective for annual and interim periods beginning after December 31, 2018. Early adoption is permitted. Management is evaluating the new guidance, but does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Completed Acquisitions Standard Bancshares, Inc. On January 6, 2017, the Company completed its acquisition of Standard Bancshares, Inc. (" Standard "), the holding company for Standard Bank and Trust Company. Pursuant to the terms of the merger agreement, on January 6, 2017, each outstanding share of Standard common stock was canceled and converted into the right to receive 0.4350 of a share of Company common stock. Based on the closing price of shares of Company common stock of $25.34 on that date, as reported by NASDAQ, the value of the merger consideration per share of Standard common stock was $11.02 . Each outstanding Standard stock settled right was redeemed for cash, and each outstanding Standard stock option and each share of Standard phantom stock was canceled and terminated in exchange for the right to receive cash, in each case, pursuant to the terms of the merger agreement. This resulted in an overall transaction value of approximately $580.7 million , which consisted of 21,057,085 shares of Company common stock and $47.1 million in cash. Goodwill of $339.2 million associated with the acquisition was recorded by the Company. All operating systems were converted during the first quarter of 2017. During the third quarter of 2017, the Company updated the fair value adjustments associated with the Standard transaction. The adjustments were recognized in the current period in accordance with accounting guidance applicable to business combinations. 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. Premier Asset Management LLC On February 28, 2017, the Company completed its acquisition of Premier Asset Management LLC ("Premier"), a registered investment advisor based in Chicago, Illinois. At the close of the acquisition, the Company acquired approximately $550.0 million of trust assets under management. 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. NI Bancshares Corporation On March 8, 2016, the Company completed its acquisition of NI Bancshares Corporation (" NI Bancshares "), the holding company for The National Bank & Trust Company of Sycamore, which included ten banking offices in northern Illinois and over $700.0 million in trust assets under management. The merger consideration was a combination of Company common stock and cash, at a purchase price of $70.1 million . Goodwill of $22.2 million associated with the acquisition was recorded by the Company. The fair value adjustments associated with this transaction were finalized during the first quarter of 2017. The following table presents the assets acquired and liabilities assumed, net of the fair value adjustments, in the Standard and NI Bancshares 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 (Amounts in thousands, except share and per share data) Standard NI Bancshares January 6, 2017 March 8, 2016 Assets Cash and due from banks and interest-bearing deposits in other banks $ 102,149 $ 72,533 Securities available-for-sale 214,107 125,843 Securities held-to-maturity — 1,864 FHLB and FRB stock 3,247 1,549 Loans 1,769,655 396,181 OREO 8,424 2,863 Investment in BOLI 55,629 8,384 Goodwill 339,207 22,174 Other intangible assets 31,072 10,408 Premises, furniture, and equipment 60,286 19,636 Accrued interest receivable and other assets 56,003 16,453 Total assets $ 2,639,779 $ 677,888 Liabilities Noninterest-bearing deposits $ 675,354 $ 130,909 Interest-bearing deposits 1,348,520 464,012 Total deposits 2,023,874 594,921 Borrowed funds — 2,416 Intangible liabilities — 230 Accrued interest payable and other liabilities 35,190 10,239 Total liabilities 2,059,064 607,806 Consideration Paid Common stock (2017 - 21,057,085 shares issued at $25.34 per share, 2016 - 3,042,494 shares issued at $18.059 per share), net of issuance costs 533,590 54,896 Cash paid 47,125 15,186 Total consideration paid 580,715 70,082 $ 2,639,779 $ 677,888 Expenses related to the acquisition and integration of the transactions above totaled $384,000 and $20.1 million during the quarter and nine months ended September 30, 2017 , respectively, and are reported as a separate component within noninterest expense in the Condensed Consolidated Statements of Income. Expenses related to the acquisition and integration of the transactions above totaled $1.2 million and $6.8 million during the quarter and nine months ended September 30, 2016 , respectively. The acquisition of Standard was considered material to the Company's financial statements; therefore, pro forma financial data and related disclosures are included in the following tables. The unaudited pro forma combined results of operations for the quarters and nine months ended September 30, 2017 and 2016 are presented as if the Standard acquisition had occurred on January 1, 2016, the first day of the Company's 2016 fiscal year. The unaudited pro forma combined results of operations are presented for illustrative purposes only and do not necessarily indicate the financial results of the combined companies had the companies actually been combined at the beginning of the period presented. Fair value adjustments included in the following table are preliminary and may be revised. The unaudited pro forma combined results of operations also do not consider any potential impacts of potential revenue enhancements, anticipated cost savings and expense efficiencies, or asset dispositions, among other factors. Acquisition and integration related expenses directly attributable to the Standard acquisition have been excluded from the following table and are estimated to total $27.0 million , of which $384,000 and $19.1 million was expensed during the quarter and nine months ended September 30, 2017 , respectively. Unaudited Pro Forma Combined Results of Operations (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Total revenues (1) $ 163,241 $ 164,786 $ 482,526 $ 462,962 Net income 38,462 32,589 106,848 85,054 (1) Includes net interest income and total noninterest income. Acquired loans are recorded at fair value, which incorporates credit risk, at the date of acquisition. No allowance for credit losses is recorded on the acquisition date. Acquired loans are separated into (i) non-PCI and (ii) 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. PCI loans are accounted for based on estimates of expected future cash flows. 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. For additional discussion regarding significant accounting policies on acquired loans see Note 1 , " Summary of Significant Accounting Policies ." The following table presents additional detail for loans acquired in the Standard transaction at the acquisition date. Standard Acquired Loans (Dollar amounts in thousands) January 6, 2017 PCI Loans Non-PCI Loans Fair value $ 126,469 $ 1,643,186 Contractually required principal and interest payments 211,931 1,937,060 Best estimate of contractual cash flows not expected to be collected (1) 57,783 100,762 Best estimate of contractual cash flows expected to be collected 154,148 1,836,298 (1) Includes interest payments not expected to be collected due to loan prepayments as well as principal and interest payments not expected to be collected due to customer default.

Securities

Securities	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Securities	SECURITIES The significant accounting policies related to securities are presented in Note 1 , " Summary of Significant Accounting Policies " to the Consolidated Financial Statements in the Company 's 2016 10-K. 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 September 30, 2017 As of December 31, 2016 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 42,567 $ 14 $ (77 ) $ 42,504 $ 48,581 $ 26 $ (66 ) $ 48,541 U.S. agency securities 154,666 303 (362 ) 154,607 183,528 519 (410 ) 183,637 Collateralized mortgage obligations ("CMOs") 949,762 459 (12,999 ) 937,222 1,064,130 969 (17,653 ) 1,047,446 Other mortgage-backed securities ("MBSs") 358,746 307 (3,580 ) 355,473 337,139 1,395 (5,879 ) 332,655 Municipal securities 204,571 1,294 (841 ) 205,024 273,319 1,245 (3,718 ) 270,846 Trust-preferred collateralized debt obligations ("CDOs") 45,851 275 (15,300 ) 30,826 47,681 261 (14,682 ) 33,260 Equity securities 7,358 185 (215 ) 7,328 3,206 147 (288 ) 3,065 Total securities available-for-sale $ 1,763,521 $ 2,837 $ (33,374 ) $ 1,732,984 $ 1,957,584 $ 4,562 $ (42,696 ) $ 1,919,450 Securities Held-to-Maturity Municipal securities $ 14,638 $ — $ (1,717 ) $ 12,921 $ 22,291 $ — $ (4,079 ) $ 18,212 Trading Securities $ 20,425 $ 17,920 Remaining Contractual Maturity of Securities (Dollar amounts in thousands) As of September 30, 2017 Available-for-Sale Held-to-Maturity Amortized Cost Fair Value Amortized Cost Fair Value One year or less $ 97,905 $ 94,691 $ 1,947 $ 1,718 After one year to five years 303,899 293,924 6,065 5,354 After five years to ten years — — 2,243 1,980 After ten years 45,851 44,346 4,383 3,869 Securities that do not have a single contractual maturity date 1,315,866 1,300,023 — — Total $ 1,763,521 $ 1,732,984 $ 14,638 $ 12,921 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 September 30, 2017 and $1.1 billion for December 31, 2016 . No securities held-to-maturity were pledged as of September 30, 2017 or December 31, 2016 . During the quarters and nine months ended September 30, 2017 and 2016 there were no material gross trading gains (losses). The following table presents net realized gains on securities available-for-sale for the quarters and nine months ended September 30, 2017 and 2016 . Securities Available-for-Sale Gains (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Gains on sales of securities: Gross realized gains $ 3,197 $ 187 $ 3,481 $ 1,266 Gross realized losses — — — (169 ) Net realized gains on sales of securities 3,197 187 3,481 1,097 Non-cash impairment charges: Other-than-temporary securities impairment ("OTTI") — — — — Net realized gains $ 3,197 $ 187 $ 3,481 $ 1,097 Securities acquired in the Standard transaction in the first quarter of 2017 were sold shortly after the acquisition date for $210.2 million , resulting in no gains or losses as the securities were recorded at fair value upon acquisition. 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. The outstanding balance of OTTI previously recognized on securities available-for-sale was $23.3 million for both September 30, 2017 and December 31, 2016 . During the quarters and nine months ended September 30, 2017 and 2016 there were no additions or reductions to the balance of OTTI related to securities available-for-sale. The following table presents the aggregate amount of unrealized losses and the aggregate related fair values of securities with unrealized losses as of September 30, 2017 and December 31, 2016 . Securities in an Unrealized Loss Position (Dollar amounts in thousands) Less Than 12 Months 12 Months or Longer Total Number of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses As of September 30, 2017 Securities Available-for-Sale U.S. treasury securities 16 $ 30,469 $ 51 $ 5,998 $ 26 $ 36,467 $ 77 U.S. agency securities 33 71,538 291 8,241 71 79,779 362 CMOs 195 607,645 7,680 241,930 5,319 849,575 12,999 MBSs 72 262,080 2,851 41,994 729 304,074 3,580 Municipal securities 138 42,951 461 17,045 380 59,996 841 CDOs 7 — — 30,015 15,300 30,015 15,300 Equity securities 2 — — 6,833 215 6,833 215 Total 463 $ 1,014,683 $ 11,334 $ 352,056 $ 22,040 $ 1,366,739 $ 33,374 Securities Held-to-Maturity Municipal securities 10 $ — $ — $ 12,921 $ 1,717 $ 12,921 $ 1,717 As of December 31, 2016 Securities Available-for-Sale U.S. treasury securities 16 $ 33,505 $ 61 $ 3,995 $ 5 $ 37,500 $ 66 U.S. agency securities 28 62,064 364 11,814 46 73,878 410 CMOs 194 523,233 10,309 411,758 7,344 934,991 17,653 MBSs 68 221,174 4,726 77,780 1,154 298,954 5,880 Municipal securities 380 133,957 3,059 29,280 659 163,237 3,718 CDOs 7 — — 30,592 14,682 30,592 14,682 Equity securities 2 404 201 2,319 86 2,723 287 Total 695 $ 974,337 $ 18,720 $ 567,538 $ 23,976 $ 1,541,875 $ 42,696 Securities Held-to-Maturity Municipal securities 14 $ — $ — $ 18,212 $ 4,079 $ 18,212 $ 4,079 Substantially all of the Company 's CMO s 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 unrealized losses as of September 30, 2017 represent OTTI related to credit deterioration. These unrealized losses are attributed to changes in interest rates and temporary market movements. The Company does not intend to sell these securities and it is not more likely than not that the Company will be required to sell them before recovery of their amortized cost basis, which may be at maturity. The unrealized losses on CDOs as of September 30, 2017 reflect changes in market activity for these securities. Management does not believe these unrealized losses represent OTTI related to credit deterioration. In addition, the Company does not intend to sell the CDOs with unrealized losses and the Company does not believe it is more likely than not that it will be required to sell them before recovery of their amortized cost basis, which may be at maturity. Significant judgment is required to calculate the fair value of the CDOs . For a detailed discussion of the CDO valuation methodology, see Note 16 , " Fair Value ."

Loans

Loans	9 Months Ended
	Sep. 30, 2017
Loans and Leases Receivable Disclosure [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 September 30, December 31, Commercial and industrial $ 3,462,612 $ 2,827,658 Agricultural 437,721 389,496 Commercial real estate: Office, retail, and industrial 1,960,367 1,581,967 Multi-family 711,101 614,052 Construction 545,666 451,540 Other commercial real estate 1,391,241 979,528 Total commercial real estate 4,608,375 3,627,087 Total corporate loans 8,508,708 6,844,241 Home equity 847,209 747,983 1-4 family mortgages 711,607 423,922 Installment 322,768 237,999 Total consumer loans 1,881,584 1,409,904 Total loans $ 10,390,292 $ 8,254,145 Deferred loan fees included in total loans $ 5,189 $ 3,838 Overdrawn demand deposits included in total loans 6,616 7,836 The increase in total loans for the quarter ended September 30, 2017 includes loans acquired in the Standard acquisition. For additional disclosure related to the Standard transaction, see Note 3 , " Acquisitions ." 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. It is the Company 's policy to review each prospective credit to determine the appropriateness and the adequacy of security or collateral prior to making a loan. In the event of borrower default, the Company seeks recovery in compliance with state lending laws, the Company 's lending standards, and credit monitoring and remediation procedures. A discussion of risk characteristics relevant to each portfolio segment is presented in Note 5 , "Loans" to the Consolidated Financial Statements in the Company 's 2016 10-K. Loan Sales The following table presents loan sales for the quarters and nine months ended September 30, 2017 and 2016 . Loan Sales (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Corporate loan sales Proceeds from sales $ 11,833 $ 12,223 $ 46,770 $ 36,082 Less book value of loans sold 11,512 11,828 45,752 34,718 Net gains on corporate loan sales (1) 321 395 1,018 1,364 1-4 family mortgage loan sales Proceeds from sales $ 73,889 $ 110,167 190,544 202,932 Less book value of loans sold 72,149 107,255 186,208 198,024 Net gains on 1-4 family mortgage loan sales (2) 1,740 2,912 4,336 4,908 Total net gains on loan sales $ 2,061 $ 3,307 $ 5,354 $ 6,272 (1) Net gains on corporate loan sales are included in other service charges, commissions, and fees in the Condensed Consolidated Statements of Income. (2) Net gains on 1-4 family mortgage loan sales are included in mortgage banking income in the Condensed Consolidated Statements of Income. The Company retained servicing responsibilities for a portion of the 1-4 family mortgage loans sold and collects servicing fees equal to a percentage of the outstanding principal balance. For additional disclosure related to the Company's obligations resulting from the sale of certain 1-4 family mortgage loans, see Note 15 , " Commitments, Guarantees, and Contingent Liabilities ."

Acquired and Covered Loans

Acquired and Covered Loans	9 Months Ended
	Sep. 30, 2017
Acquired Loans [Abstract]
Acquired and Covered Loans	ACQUIRED AND COVERED LOANS The significant accounting policies related to acquired and covered loans, which are classified as PCI and non-PCI , are presented in Note 1 , " Summary of Significant Accounting Policies ." The following table presents the carrying amount of acquired and covered PCI and non-PCI loans as of September 30, 2017 and December 31, 2016 . Acquired and Covered Loans (1) (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 PCI Non-PCI Total PCI Non-PCI Total Acquired loans $ 150,405 $ 1,694,032 $ 1,844,437 $ 53,772 $ 613,339 $ 667,111 Covered loans 6,871 12,474 19,345 7,895 15,379 23,274 Total acquired and covered loans $ 157,276 $ 1,706,506 $ 1,863,782 $ 61,667 $ 628,718 $ 690,385 (1) Included in loans in the Consolidated Statements of Condition. The outstanding balance of PCI loans was $229.1 million and $84.8 million as of September 30, 2017 and December 31, 2016 , respectively. The increase in acquired loans compared to December 31, 2016 includes loans acquired in the Standard acquisition. For additional disclosure related to the Standard transaction, see Note 3 , " Acquisitions ." Acquired non-PCI loans that are renewed are no longer classified as acquired loans. These loans totaled $304.0 million and $117.6 million as of September 30, 2017 and December 31, 2016 , respectively. In connection with the FDIC Agreements , the Company recorded an indemnification asset. To maintain eligibility for the loss share reimbursement, the Company is required to follow certain servicing procedures as specified in the FDIC Agreements . The Company was in compliance with those requirements as of September 30, 2017 and December 31, 2016 . Rollforwards of the carrying value of the FDIC indemnification asset for the quarters and nine months ended September 30, 2017 and 2016 are presented in the following table. Changes in the FDIC Indemnification Asset (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 3,918 $ 5,171 $ 4,522 $ 3,903 Amortization (302 ) (302 ) (906 ) (884 ) Change in expected reimbursements from the FDIC for changes in expected credit losses (123 ) (228 ) (653 ) (487 ) Net payments to the FDIC 123 191 653 2,300 Ending balance $ 3,616 $ 4,832 $ 3,616 $ 4,832 Changes in the accretable yield for acquired and covered PCI loans were as follows. Changes in Accretable Yield (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balances $ 39,870 $ 25,082 $ 19,385 $ 24,912 Additions — — 27,316 3,981 Accretion (4,263 ) (2,763 ) (12,106 ) (6,612 ) Other (1) 478 (1,012 ) 1,490 (974 ) Ending balance $ 36,085 $ 21,307 $ 36,085 $ 21,307 (1) Increases represent a rise in the expected future cash flows to be collected over the remaining estimated life of the underlying portfolio while decreases result from the resolution of certain loans occurring earlier than anticipated. Total accretion on acquired and covered PCI and non-PCI loans for the quarter and nine months ended September 30, 2017 was $7.6 million and $27.7 million , respectively, and $4.6 million and $11.9 million for the same periods in 2016 .

Past Due Loans, Allowance For C

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 . 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 (2) 90 Days or More Past Due, Still Accruing Interest As of September 30, 2017 Commercial and industrial $ 3,444,056 $ 14,536 $ 4,020 $ 18,556 $ 3,462,612 $ 41,504 $ 1,166 Agricultural 436,693 325 703 1,028 437,721 380 335 Commercial real estate: Office, retail, and industrial 1,950,010 4,411 5,946 10,357 1,960,367 12,221 — Multi-family 707,959 3,013 129 3,142 711,101 153 129 Construction 545,119 29 518 547 545,666 146 374 Other commercial real estate 1,387,969 1,356 1,916 3,272 1,391,241 2,239 349 Total commercial real estate 4,591,057 8,809 8,509 17,318 4,608,375 14,759 852 Total corporate loans 8,471,806 23,670 13,232 36,902 8,508,708 56,643 2,353 Home equity 840,966 3,729 2,514 6,243 847,209 5,529 44 1-4 family mortgages 707,498 3,714 395 4,109 711,607 3,004 — Installment 320,210 2,116 442 2,558 322,768 — 442 Total consumer loans 1,868,674 9,559 3,351 12,910 1,881,584 8,533 486 Total loans $ 10,340,480 $ 33,229 $ 16,583 $ 49,812 $ 10,390,292 $ 65,176 $ 2,839 As of December 31, 2016 Commercial and industrial $ 2,816,442 $ 6,426 $ 4,790 $ 11,216 $ 2,827,658 $ 29,938 $ 374 Agricultural 388,596 — 900 900 389,496 181 736 Commercial real estate: Office, retail, and industrial 1,564,007 5,327 12,633 17,960 1,581,967 17,277 1,129 Multi-family 612,446 858 748 1,606 614,052 311 604 Construction 450,927 332 281 613 451,540 286 — Other commercial real estate 974,575 1,307 3,646 4,953 979,528 2,892 1,526 Total commercial real estate 3,601,955 7,824 17,308 25,132 3,627,087 20,766 3,259 Total corporate loans 6,806,993 14,250 22,998 37,248 6,844,241 50,885 4,369 Home equity 740,919 4,545 2,519 7,064 747,983 5,465 109 1-4 family mortgages 420,264 2,652 1,006 3,658 423,922 2,939 272 Installment 236,264 1,476 259 1,735 237,999 — 259 Total consumer loans 1,397,447 8,673 3,784 12,457 1,409,904 8,404 640 Total loans $ 8,204,440 $ 22,923 $ 26,782 $ 49,705 $ 8,254,145 $ 59,289 $ 5,009 (1) PCI loans with an accretable yield are considered current. (2) Includes PCI loans of $239,000 and $681,000 as of September 30, 2017 and December 31, 2016 , respectively, which no longer have an accretable yield as estimates of expected future cash flows have decreased since the acquisition due to credit deterioration. 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 quarters and nine months ended September 30, 2017 and 2016 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 Quarter ended September 30, 2017 Beginning balance $ 46,271 $ 15,008 $ 2,919 $ 4,094 $ 7,479 $ 16,600 $ 1,000 $ 93,371 Charge-offs (8,935 ) (14 ) — 6 (6 ) (1,617 ) — (10,566 ) Recoveries 698 1,825 2 19 25 331 — 2,900 Net charge-offs (8,237 ) 1,811 2 25 19 (1,286 ) — (7,666 ) Provision for loan losses and other 13,994 (5,129 ) (296 ) 161 (257 ) 1,636 — 10,109 Ending balance $ 52,028 $ 11,690 $ 2,625 $ 4,280 $ 7,241 $ 16,950 $ 1,000 $ 95,814 Quarter ended September 30, 2016 Beginning balance $ 40,084 $ 12,985 $ 2,933 $ 2,239 $ 7,492 $ 14,372 $ 1,400 $ 81,505 Charge-offs (1,760 ) (2,193 ) — — (509 ) (1,488 ) — (5,950 ) Recoveries 615 42 69 9 94 326 — 1,155 Net charge-offs (1,145 ) (2,151 ) 69 9 (415 ) (1,162 ) — (4,795 ) Provision for loan losses and other 3,579 3,019 1,048 916 1,490 (54 ) (400 ) 9,598 Ending balance $ 42,518 $ 13,853 $ 4,050 $ 3,164 $ 8,567 $ 13,156 $ 1,000 $ 86,308 Nine months ended September 30, 2017 Beginning balance $ 40,709 $ 17,595 $ 3,261 $ 3,444 $ 7,739 $ 13,335 $ 1,000 $ 87,083 Charge-offs (15,966 ) (141 ) — (38 ) (721 ) (4,837 ) — (21,703 ) Recoveries 2,764 2,808 36 258 205 1,097 — 7,168 Net charge-offs (13,202 ) 2,667 36 220 (516 ) (3,740 ) — (14,535 ) Provision for loan losses and other 24,521 (8,572 ) (672 ) 616 18 7,355 — 23,266 Ending balance $ 52,028 $ 11,690 $ 2,625 $ 4,280 $ 7,241 $ 16,950 $ 1,000 $ 95,814 Nine months ended September 30, 2016 Beginning balance $ 37,074 $ 13,124 $ 2,469 $ 1,440 $ 6,109 $ 13,414 $ 1,225 $ 74,855 Charge-offs (5,684 ) (4,358 ) (288 ) (134 ) (2,833 ) (3,975 ) — (17,272 ) Recoveries 1,693 153 95 44 314 975 — 3,274 Net charge-offs (3,991 ) (4,205 ) (193 ) (90 ) (2,519 ) (3,000 ) — (13,998 ) Provision for loan losses and other 9,435 4,934 1,774 1,814 4,977 2,742 (225 ) 25,451 Ending balance $ 42,518 $ 13,853 $ 4,050 $ 3,164 $ 8,567 $ 13,156 $ 1,000 $ 86,308 The table below provides a breakdown of loans and the related allowance for credit losses by portfolio segment as of September 30, 2017 and December 31, 2016 . 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 September 30, 2017 Commercial, industrial, and agricultural $ 39,121 $ 3,835,995 $ 25,217 $ 3,900,333 $ 3,408 $ 48,107 $ 513 $ 52,028 Commercial real estate: Office, retail, and industrial 11,211 1,932,332 16,824 1,960,367 9 10,291 1,390 11,690 Multi-family 395 696,490 14,216 711,101 — 2,524 101 2,625 Construction — 532,016 13,650 545,666 — 4,060 220 4,280 Other commercial real estate 656 1,325,280 65,305 1,391,241 — 6,126 1,115 7,241 Total commercial real estate 12,262 4,486,118 109,995 4,608,375 9 23,001 2,826 25,836 Total corporate loans 51,383 8,322,113 135,212 8,508,708 3,417 71,108 3,339 77,864 Consumer — 1,859,520 22,064 1,881,584 — 15,684 1,266 16,950 Reserve for unfunded commitments — — — — — 1,000 — 1,000 Total loans $ 51,383 $ 10,181,633 $ 157,276 $ 10,390,292 $ 3,417 $ 87,792 $ 4,605 $ 95,814 As of December 31, 2016 Commercial, industrial, and agricultural $ 24,645 $ 3,189,327 $ 3,182 $ 3,217,154 $ 507 $ 39,554 $ 648 $ 40,709 Commercial real estate: Office, retail, and industrial 16,287 1,553,234 12,446 1,581,967 — 16,148 1,447 17,595 Multi-family 398 601,429 12,225 614,052 — 3,059 202 3,261 Construction 34 447,058 4,448 451,540 — 3,280 164 3,444 Other commercial real estate 1,286 965,900 12,342 979,528 18 6,613 1,108 7,739 Total commercial real estate 18,005 3,567,621 41,461 3,627,087 18 29,100 2,921 32,039 Total corporate loans 42,650 6,756,948 44,643 6,844,241 525 68,654 3,569 72,748 Consumer — 1,392,880 17,024 1,409,904 — 12,210 1,125 13,335 Reserve for unfunded commitments — — — — — 1,000 — 1,000 Total loans $ 42,650 $ 8,149,828 $ 61,667 $ 8,254,145 $ 525 $ 81,864 $ 4,694 $ 87,083 Loans Individually Evaluated for Impairment The following table presents loans individually evaluated for impairment by class of loan as of September 30, 2017 and December 31, 2016 . PCI loans are excluded from this disclosure. Impaired Loans Individually Evaluated by Class (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 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 $ 24,688 $ 14,433 $ 47,700 $ 3,408 $ 11,579 $ 13,066 $ 29,514 $ 507 Agricultural — — — — — — — — Commercial real estate: Office, retail, and industrial 7,146 4,065 14,480 9 16,287 — 21,057 — Multi-family 395 — 395 — 398 — 398 — Construction — — — — 34 — 34 — Other commercial real estate 656 — 754 — 1,016 270 2,141 18 Total commercial real estate 8,197 4,065 15,629 9 17,735 270 23,630 18 Total impaired loans individually evaluated for impairment $ 32,885 $ 18,498 $ 63,329 $ 3,417 $ 29,314 $ 13,336 $ 53,144 $ 525 The following table presents the average recorded investment and interest income recognized on impaired loans by class for the quarters and nine months ended September 30, 2017 and 2016 . PCI loans are excluded from this disclosure. Average Recorded Investment and Interest Income Recognized on Impaired Loans by Class (Dollar amounts in thousands) Quarters Ended September 30, 2017 2016 Average Interest Income Recognized (1) Average Interest Income Recognized (1) Commercial and industrial $ 44,682 $ 368 $ 7,829 $ 57 Agricultural 140 — — — Commercial real estate: Office, retail, and industrial 12,496 — 16,101 3 Multi-family 396 — 399 11 Construction — — 34 — Other commercial real estate 1,415 — 2,561 — Total commercial real estate 14,307 — 19,095 14 Total impaired loans $ 59,129 $ 368 $ 26,924 $ 71 Nine Months Ended September 30, 2017 2016 Average Interest (1) Average Interest (1) Commercial and industrial $ 32,765 $ 924 $ 5,312 $ 107 Agricultural 348 — — — Commercial real estate: Office, retail, and industrial 13,680 262 12,012 80 Multi-family 396 28 500 12 Construction 9 136 70 — Other commercial real estate 1,652 20 3,190 72 Total commercial real estate 15,737 446 15,772 164 Total impaired loans $ 48,850 $ 1,370 $ 21,084 $ 271 (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 September 30, 2017 and December 31, 2016 . Corporate Credit Quality Indicators by Class (Dollar amounts in thousands) Pass Special Mention (1) (4) Substandard (2) (4) Non-accrual (3) Total As of September 30, 2017 Commercial and industrial $ 3,286,087 $ 72,491 $ 62,530 $ 41,504 $ 3,462,612 Agricultural 417,612 13,310 6,419 380 437,721 Commercial real estate: Office, retail, and industrial 1,877,165 25,919 45,062 12,221 1,960,367 Multi-family 703,659 5,433 1,856 153 711,101 Construction 525,097 9,113 11,310 146 545,666 Other commercial real estate 1,334,385 32,693 21,924 2,239 1,391,241 Total commercial real estate 4,440,306 73,158 80,152 14,759 4,608,375 Total corporate loans $ 8,144,005 $ 158,959 $ 149,101 $ 56,643 $ 8,508,708 As of December 31, 2016 Commercial and industrial $ 2,638,833 $ 92,340 $ 66,547 $ 29,938 $ 2,827,658 Agricultural 366,382 17,039 5,894 181 389,496 Commercial real estate: Office, retail, and industrial 1,491,170 34,007 39,513 17,277 1,581,967 Multi-family 607,342 4,370 2,029 311 614,052 Construction 438,946 111 12,197 286 451,540 Other commercial real estate 951,284 11,808 13,544 2,892 979,528 Total commercial real estate 3,488,742 50,296 67,283 20,766 3,627,087 Total corporate loans $ 6,493,957 $ 159,675 $ 139,724 $ 50,885 $ 6,844,241 (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 well-defined weaknesses 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 well-defined weaknesses that may jeopardize the liquidation of the debt or result in a loss if the deficiencies are not corrected. (4) Total special mention and substandard loans includes accruing TDR s of $664,000 as of September 30, 2017 and $834,000 as of December 31, 2016 . Consumer Credit Quality Indicators by Class (Dollar amounts in thousands) Performing Non-accrual Total As of September 30, 2017 Home equity $ 841,680 $ 5,529 $ 847,209 1-4 family mortgages 708,603 3,004 711,607 Installment 322,768 — 322,768 Total consumer loans $ 1,873,051 $ 8,533 $ 1,881,584 As of December 31, 2016 Home equity $ 742,518 $ 5,465 $ 747,983 1-4 family mortgages 420,983 2,939 423,922 Installment 237,999 — 237,999 Total consumer loans $ 1,401,500 $ 8,404 $ 1,409,904 TDR s TDR s 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 TDR s by class as of September 30, 2017 and December 31, 2016 . See Note 1, "Summary of Significant Accounting Policies," for the accounting policy for TDR s. TDR s by Class (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 Accruing Non-accrual (1) Total Accruing Non-accrual (1) Total Commercial and industrial $ 269 $ 22,780 $ 23,049 $ 281 $ 150 $ 431 Agricultural — — — — — — Commercial real estate: Office, retail, and industrial — 4,512 4,512 155 4,733 4,888 Multi-family 577 153 730 586 168 754 Construction — — — — — — Other commercial real estate 194 — 194 268 48 316 Total commercial real estate 771 4,665 5,436 1,009 4,949 5,958 Total corporate loans 1,040 27,445 28,485 1,290 5,099 6,389 Home equity 88 755 843 177 820 997 1-4 family mortgages 685 462 1,147 824 378 1,202 Installment — — — — — — Total consumer loans 773 1,217 1,990 1,001 1,198 2,199 Total loans $ 1,813 $ 28,662 $ 30,475 $ 2,291 $ 6,297 $ 8,588 (1) These TDR s are included in non-accrual loans in the preceding tables. TDR s are included in the calculation of the allowance for credit losses in the same manner as impaired loans. There were $1.3 million in specific reserves related to TDR s as of September 30, 2017 . There were no specific reserves related to TDRs as of December 31, 2016 . The following table presents a summary of loans that were restructured during the quarter and nine months ended September 30, 2017 . There were no material restructures during the quarter and nine months ended September 30, 2016 . 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 Quarter ended September 30, 2017 Commercial and industrial 10 $ 25,811 $ 196 $ — $ 1,736 $ 24,271 Office, retail, and industrial 2 3,656 — — — 3,656 Total TDRs restructured during the period 12 $ 29,467 $ 196 $ — $ 1,736 $ 27,927 Nine months ended September 30, 2017 Commercial and industrial 12 $ 26,733 $ 196 $ — $ 1,736 $ 25,193 Office, retail, and industrial 2 3,656 — — — 3,656 Total TDRs restructured during the period 14 $ 30,389 $ 196 $ — $ 1,736 $ 28,849 Accruing TDR s that do not perform in accordance with their modified terms are transferred to non-accrual. There were no material TDR s that defaulted within twelve months of the restructure date during the quarters and nine months ended September 30, 2017 and 2016 . A rollforward of the carrying value of TDR s for the quarters and nine months ended September 30, 2017 and 2016 is presented in the following table. TDR Rollforward (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Accruing Beginning balance $ 2,029 $ 2,491 $ 2,291 $ 2,743 Additions 14,897 — 15,819 — Net payments received (1,798 ) (22 ) (1,905 ) (91 ) Net transfers to non-accrual (13,315 ) (101 ) (14,392 ) (284 ) Ending balance 1,813 2,368 1,813 2,368 Non-accrual Beginning balance 3,036 1,690 6,297 2,324 Additions 14,570 — 14,570 — Net payments received (127 ) (31 ) (4,352 ) (609 ) Charge-offs (2,132 ) (170 ) (2,245 ) (409 ) Net transfers from accruing 13,315 101 14,392 284 Ending balance 28,662 1,590 28,662 1,590 Total TDRs $ 30,475 $ 3,958 $ 30,475 $ 3,958 For TDR s 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. Loans that were not restructured at market rates and terms, that are not in compliance with the modified terms, or for which there is a concern about the future ability of the borrower to meet its obligations under the modified terms, continue to be separately reported as restructured until paid in full or charged-off. There were no material commitments to lend additional funds to borrowers with TDR s as of September 30, 2017 and December 31, 2016 .

Premises, Furniture, and Equipm

Premises, Furniture, and Equipment	9 Months Ended
	Sep. 30, 2017
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 September 30, December 31, Land $ 30,267 $ 18,304 Premises 119,325 94,369 Furniture and equipment 114,547 105,859 Total cost 264,139 218,532 Accumulated depreciation (142,001 ) (140,030 ) Net book value of premises, furniture, and equipment 122,138 78,502 Assets held-for-sale 9,157 4,075 Total premises, furniture, and equipment $ 131,295 $ 82,577 During 2016, the Bank completed a sale-leaseback transaction, whereby the Bank sold to a third party for an aggregate cash purchase price of $150.3 million , 55 properties with book values totaling $58.8 million , owned and operated by the Bank as branches. The Bank concurrently entered into triple net lease agreements with certain affiliates of the third party for each of the branches sold. Subject to the right of the Bank to terminate certain of the lease agreements at the end of the eleventh year, the lease agreements have initial terms of 14 years. Each lease agreement provides the Bank with five consecutive renewal options of five years each. The sale-leaseback transaction resulted in a pre-tax gain of $88.0 million , net of transaction related expenses, with $76.1 million of deferred pre-tax gains remaining as of September 30, 2017 . As of September 30, 2017 and December 31, 2016 assets held-for-sale consisted of former branches that are no longer in operation and parcels of land previously purchased for expansion. Depreciation on premises, furniture, and equipment totaled $3.5 million and $10.5 million for the quarter and nine months ended September 30, 2017 , respectively. Depreciation on premises, furniture, and equipment totaled $3.4 million and $10.1 million for the same periods in 2016 . Operating Leases As of September 30, 2017 , the Company was obligated to utilize certain premises and equipment under certain non-cancelable operating leases, which expire at various dates through the year ending December 31, 2033 . Many of these leases contain renewal options and certain leases provide 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. 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 as of September 30, 2017 . Future Minimum Operating Lease Payments (Dollar amounts in thousands) Total One year or less $ 19,298 After one year to two years 17,737 After two years to three years 17,008 After three years to four years 16,815 After four years to five years 16,550 After five years 120,048 Total minimum lease payments $ 207,456 As of September 30, 2017 , deferred pre-tax gains of $76.1 million related to the sale-lease back transaction will be accreted as a reduction to lease expense in other expenses on the Condensed Consolidated Statements of Income on a straight-line basis over the initial terms of the leases. The Company assumed certain operating leases related to various branches in previous acquisitions. An intangible liability is recorded when the cash flows of a lease exceeds its fair market value. This intangible liability will be accreted into income as a reduction to net occupancy and equipment expense using the straight-line method over the initial term of each lease, which expire between 2018 and 2030. The intangible liability is included in accrued interest and other liabilities in the Consolidated Statements of Financial Condition. The following table presents the remaining scheduled accretion of the intangible liability by year. Scheduled Accretion of Operating Lease Intangible (Dollar amounts in thousands) Total One year or less $ 1,011 After one year to two years 742 After two years to three years 648 After three years to four years 648 After four years to five years 648 After five years 3,511 Total accretion $ 7,208 The following table presents net operating lease expense for the quarters and nine months ended September 30, 2017 and 2016 . Net Operating Lease Expense (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Lease expense charged to operations $ 4,747 $ 2,229 $ 14,027 $ 5,729 Accretion of operating lease intangible (1) (295 ) (295 ) (885 ) (876 ) Accretion of deferred gain on sale-leaseback transaction (1) (1,463 ) — (4,409 ) — Rental income from premises leased to others (1) (171 ) (118 ) (521 ) (404 ) Net operating lease expense $ 2,818 $ 1,816 $ 8,212 $ 4,449 (1) Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2017
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, 2016. It was determined that no impairment existed as of that date or as of September 30, 2017 . For a discussion of the accounting policies for goodwill and other intangible assets, see Note 1 , " Summary of Significant Accounting Policies " to the Consolidated Financial Statements in the Company 's 2016 10-K. The following table presents changes in the carrying amount of goodwill for the quarters and nine months ended September 30, 2017 and 2016 . Changes in the Carrying Amount of Goodwill (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 691,527 $ 341,513 $ 340,879 $ 319,007 Acquisitions (46 ) (756 ) 350,602 21,750 Ending balance $ 691,481 $ 340,757 $ 691,481 $ 340,757 The decrease in goodwill for the quarter ended September 30, 2017 resulted from measurement period adjustments associated with the Standard transaction. The increase for the nine months ended September 30, 2017 resulted from the Standard and Premier acquisitions and measurement period adjustments related to finalizing the fair values of the assets acquired and liabilities assumed in the NI Bancshares acquisition. The decrease in goodwill for the quarter ended September 30, 2016 resulted from measurement period adjustments associated with the NI Bancshares acquisition. The increase for the nine months ended September 30, 2016 resulted from the NI Bancshares acquisition. The Company's other intangible assets are 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 its carrying amount may not be recoverable. The increase in other intangible assets for the nine months ended September 30, 2017 resulted from the Standard and Premier acquisitions. The increase in other intangible assets for the nine months ended September 30, 2016 resulted from the NI Bancshares acquisition. During the quarters ended September 30, 2017 and September 30, 2016 there were no events or circumstances to indicate impairment. Other Intangible Assets (Dollar amounts in thousands) Nine Months Ended September 30, 2017 2016 Gross Accumulated Amortization Net Gross Accumulated Amortization Net Beginning balance $ 58,959 $ 32,962 $ 25,997 $ 48,550 $ 28,280 $ 20,270 Additions 39,017 — 39,017 10,409 — 10,409 Amortization expense — 6,059 (6,059 ) — 3,475 (3,475 ) Ending balance $ 97,976 $ 39,021 $ 58,955 $ 58,959 $ 31,755 $ 27,204 Scheduled Amortization of Other Intangible Assets (Dollar amounts in thousands) Total Year Ending September 30, 2018 $ 7,173 2019 7,083 2020 7,036 2021 6,970 2022 6,898 2023 and thereafter 23,795 Total $ 58,955

Deposits

Deposits	9 Months Ended
	Sep. 30, 2017
Deposits [Abstract]
Deposits	DEPOSITS The following table presents the Company's deposits by type. Summary of Deposits (Dollar amounts in thousands) As of September 30, December 31, Demand deposits $ 3,580,922 $ 2,766,748 Savings deposits 2,022,717 1,615,833 NOW accounts 2,048,893 1,675,421 Money market deposits 1,969,865 1,577,316 Time deposits less than $100,000 888,238 755,558 Time deposits greater than $100,000 697,862 437,727 Total deposits $ 11,208,497 $ 8,828,603 The increase in total deposits for the nine months ended September 30, 2017 includes deposits assumed in the Standard acquisition. For additional disclosure related to the Standard transaction, see Note 3 , " Acquisitions ."

Borrowed Funds

Borrowed Funds	9 Months Ended
	Sep. 30, 2017
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 September 30, December 31, Securities sold under agreements to repurchase $ 110,536 $ 129,008 FHLB advances 590,000 750,000 Total borrowed funds $ 700,536 $ 879,008 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. The securities underlying the agreements remain in the respective asset accounts. 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 municipal and mortgage-backed securities. As of September 30, 2017 , the Company held various short-term FHLB advances with fixed interest rates that range from 1.18% to 1.24% and maturity dates that range from October 2, 2017 to December 1, 2017 . 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 14 "Derivative Instruments and Hedging Activities" for a detailed discussion of interest rate swaps. 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, 2017, the Company entered into a first amendment to this credit facility, which extends the maturity to September 26, 2018. 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 expects to use this line of credit for general corporate purposes. As of September 30, 2017 , no amount was outstanding under the facility.

Material Transactions Affecting

Material Transactions Affecting Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Material Transactions Affecting Stockholders' Equity	MATERIAL TRANSACTIONS AFFECTING STOCKHOLDERS' EQUITY 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.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Common Share	EARNINGS PER COMMON SHARE The table below displays the calculation of basic and diluted earnings per common share (" EPS "). Basic and Diluted EPS (Amounts in thousands, except per share data) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Net income $ 38,235 $ 28,402 $ 96,040 $ 71,631 Net income applicable to non-vested restricted shares (340 ) (324 ) (910 ) (826 ) Net income applicable to common shares $ 37,895 $ 28,078 $ 95,130 $ 70,805 Weighted-average common shares outstanding: Weighted-average common shares outstanding (basic) 101,752 80,396 101,307 79,589 Dilutive effect of common stock equivalents 20 13 20 13 Weighted-average diluted common shares outstanding 101,772 80,409 101,327 79,602 Basic EPS $ 0.37 $ 0.35 $ 0.94 $ 0.89 Diluted EPS $ 0.37 $ 0.35 $ 0.94 $ 0.89 Anti-dilutive shares not included in the computation of diluted EPS (1) 190 454 242 510 (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.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2017
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." Fair Value Hedges The Company hedges the fair value of fixed rate commercial real estate loans using interest rate swaps through which the Company pays fixed amounts and receives variable amounts. These derivative contracts are designated as fair value hedges. Fair Value Hedges (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Gross notional amount outstanding $ 5,583 $ 5,958 Derivative liability fair value (146 ) (282 ) Weighted-average interest rate received 3.23 % 2.63 % Weighted-average interest rate paid 5.96 % 5.96 % Weighted-average maturity (in years) 1.10 1.84 Fair value of derivative (1) $ 157 $ 296 (1) This amount represents the fair value if credit risk related contingent features were triggered. Hedge ineffectiveness is recognized in other noninterest income in the Condensed Consolidated Statements of Income. For the quarters and nine months ended September 30, 2017 and 2016 , gains or losses related to fair value hedge ineffectiveness were not material. Cash Flow Hedges As of September 30, 2017 , the Company hedged $980.0 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 $980.0 million 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 $415.0 million began on various dates between June of 2015 and February of 2017, and mature between June of 2019 and February of 2020. The remaining forward starting interest rate swaps totaling $565.0 million begin at various dates between February of 2018 and February of 2020 and mature between February of 2020 and April of 2022. The weighted-average fixed interest rate to be paid on these interest rate swaps that have not yet begun was 1.96% as of September 30, 2017 . These derivative contracts are designated as cash flow hedges. Cash Flow Hedges (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Gross notional amount outstanding $ 1,960,000 $ 1,470,000 Derivative asset fair value 3,234 5,402 Derivative liability fair value (6,729 ) (7,390 ) Weighted-average interest rate received 1.55 % 1.37 % Weighted-average interest rate paid 1.51 % 1.11 % Weighted-average maturity (in years) 2.50 2.83 The effective portion of gains or losses on cash flow hedges is recorded in accumulated other comprehensive loss on an after-tax basis and is subsequently reclassified to interest income or expense in the period that the forecasted hedged item impacts earnings. Hedge effectiveness is determined using a regression analysis at the inception of the hedge relationship and on an ongoing basis. For the quarters and nine months ended September 30, 2017 and 2016, there were no material gains or losses related to cash flow hedge ineffectiveness. As of September 30, 2017 , the Company estimates that $581,000 will be reclassified from accumulated other comprehensive loss as a decrease 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 September 30, 2017 and December 31, 2016 , 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 $2.6 million and $6.2 million were recorded in noninterest income for the quarter and nine months ended September 30, 2017 , respectively. There were $2.9 million and $8.2 million of capital market products income recorded for the quarter and nine months ended September 30, 2016 , respectively. Other Derivative Instruments (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Gross notional amount outstanding $ 2,463,967 $ 1,656,612 Derivative asset fair value 18,268 13,478 Derivative liability fair value (14,443 ) (13,478 ) Fair value of derivative (1) 14,704 13,753 (1) This amount represents the fair value if credit risk related contingent features 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 periods presented. The Company had no other derivative instruments as of September 30, 2017 and December 31, 2016 . The Company does not enter into derivative transactions for purely speculative purposes. 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 September 30, 2017 and December 31, 2016 , these collateral agreements covered 100% of the fair value of the Company's outstanding fair value hedges. 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 September 30, 2017 and December 31, 2016 . Fair Value of Offsetting Derivatives (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 Assets Liabilities Assets Liabilities Gross amounts recognized $ 21,502 $ 21,318 $ 18,880 $ 21,150 Less: amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition (1) 21,502 21,318 18,880 21,150 Gross amounts not offset in the Consolidated Statements of Financial Condition: Offsetting derivative positions (16,557 ) (16,557 ) (10,889 ) (10,889 ) Cash collateral pledged — (4,761 ) — (10,261 ) Net credit exposure $ 4,945 $ — $ 7,991 $ — (1) Included in other assets or other liabilities in the Consolidated Statements of Financial Condition. As of September 30, 2017 and December 31, 2016 , 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 September 30, 2017 and December 31, 2016 the Company was in compliance with these provisions.

Commitments, Guarantees, and Co

Commitments, Guarantees, and Contingent Liabilities	9 Months Ended
	Sep. 30, 2017
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 and 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 September 30, 2017 December 31, 2016 Commitments to extend credit: Commercial, industrial, and agricultural $ 1,739,259 $ 1,522,152 Commercial real estate 322,705 397,423 Home equity 512,560 426,384 Other commitments (1) 246,609 214,943 Total commitments to extend credit $ 2,821,133 $ 2,560,902 Letters of credit $ 132,990 $ 100,430 (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 quarters and nine months ended September 30, 2017 and 2016 . Legal Proceedings In the ordinary course of business, there were certain legal proceedings pending against the Company and its subsidiaries at September 30, 2017 . 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 financial position, results of operations, or cash flows.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 As of December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets: Trading securities: Money market funds $ 1,738 $ — $ — $ 1,645 $ — $ — Mutual funds 18,687 — — 16,275 — — Total trading securities 20,425 — — 17,920 — — Securities available-for-sale: U.S. treasury securities 42,504 — — 48,541 — — U.S. agency securities — 154,607 — — 183,637 — CMOs — 937,222 — — 1,047,446 — MBSs — 355,473 — — 332,655 — Municipal securities — 205,024 — — 270,846 — CDOs — — 30,826 — — 33,260 Equity securities — 7,328 — — 3,065 — Total securities available-for-sale 42,504 1,659,654 30,826 48,541 1,837,649 33,260 Mortgage servicing rights ("MSRs") (1) — — 5,766 — — 6,120 Derivative assets (1) — 21,502 — — 18,880 — Liabilities: Derivative liabilities (2) $ — $ 21,318 $ — $ — $ 21,150 $ — (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. Trading Securities The Company's trading securities consist of diversified investment securities held in a grantor trust and are invested in money market and mutual funds. The fair value of these 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 of 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. CDOs are classified in level 3 of the fair value hierarchy. The Company estimates the fair values for each CDO using discounted cash flow analyses with the assistance of a structured credit valuation firm. This methodology is based on credit analysis and historical financial data for each of the issuers underlying the CDOs (the "Issuers"). These estimates are highly subjective and sensitive to several significant, unobservable inputs. The cash flows for each Issuer are then discounted to present values using LIBOR plus an adjustment to reflect the impact of market factors. Finally, the discounted cash flows for each Issuer are aggregated to derive the estimated fair value for the specific CDO . The following table presents the ranges of significant, unobservable inputs calculated using the weighted-average of the Issuers used by the Company as of September 30, 2017 and December 31, 2016. Significant Unobservable Inputs Used in the Valuation of CDOs As of September 30, 2017 December 31, 2016 Probability of prepayment 0.0 % - 11.4% 0.0 % - 10.9% Probability of default 16.5 % - 44.8% 16.7 % - 46.8% Loss given default 93.4 % - 99.2% 93.3 % - 98.9% Probability of deferral cure 0.0 % - 100.0% 7.6 % - 100.0% Most Issuers have the right to prepay the securities on the fifth anniversary of issuance and under other limited circumstances. To estimate prepayments, a credit analysis of each Issuer is performed to estimate its ability and likelihood to fund a prepayment. If a prepayment occurs, the Company receives cash equal to the par value for the portion of the CDO associated with that Issuer. The likelihood that an Issuer who is currently deferring payment on the securities will pay all deferred amounts and remain current thereafter is based on an analysis of the Issuer's asset quality, leverage ratios, and other measures of financial viability. The impact of changes in these key inputs could result in a significantly higher or lower fair value measurement for each CDO . The timing of the default, the magnitude of the default, and the timing and magnitude of the cure probability are directly interrelated. Defaults that occur sooner and/or are greater than anticipated have a negative impact on the valuation. In addition, a high cure probability assumption has a positive effect on the fair value, and, if a cure event takes place sooner than anticipated, the impact on the valuation is also favorable. Management monitors the valuation results of each CDO on a quarterly basis, which includes an analysis of historical pricing trends for these types of securities, overall economic conditions (such as tracking LIBOR curves), and the performance of the Issuers' industries. Annually, management validates significant assumptions by reviewing detailed back-testing performed by the structured credit valuation firm. A rollforward of the carrying value of CDOs for the quarters and nine months ended September 30, 2017 and 2016 is presented in the following table. Carrying Value of CDOs (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 33,454 $ 30,431 $ 33,260 $ 31,529 Change in other comprehensive income (1) (739 ) 1,794 (604 ) 764 Other (1,889 ) (326 ) (1,830 ) (394 ) Ending balance $ 30,826 $ 31,899 $ 30,826 $ 31,899 (1) Included in unrealized holding gains in the Consolidated Statements of Comprehensive Income. During the third quarter of 2017, three CDOs with carrying values totaling $1.9 million were sold at gains. MSR s The Company services loans for others totaling $616.7 million as of September 30, 2017 and $640.5 million as of December 31, 2016 . 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 MSR s 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 MSR s as of September 30, 2017 and December 31, 2016 . Significant Unobservable Inputs Used in the Valuation of MSR s As of September 30, 2017 December 31, 2016 Prepayment speed 8.8 % - 26.2% 7.7 % - 22.8% Maturity (months) 7 - 91 12 - 103 Discount rate 9.5 % - 13.0% 9.5 % - 13.0% The impact of changes in these key inputs could result in a significantly higher or lower fair value measurement for MSR s. 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 MSR s for the quarters and nine months ended September 30, 2017 and 2016 is presented in the following table. Carrying Value of MSR s (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 5,925 $ 4,938 $ 6,120 $ 1,853 Additions from acquisition — — — 3,092 New MSRs 161 581 522 928 Total losses included in earnings (1) : Changes in valuation inputs and assumptions (121 ) (205 ) (209 ) (377 ) Other changes in fair value (2) (199 ) (238 ) (667 ) (420 ) Ending balance $ 5,766 $ 5,076 $ 5,766 $ 5,076 Contractual servicing fees earned (1) $ 379 $ 373 $ 1,158 $ 922 (1) Included in mortgage banking income in the Condensed Consolidated Statements of Income and related to assets held as of September 30, 2017 and 2016 . (2) Primarily represents changes in expected future cash flows due to payoffs and paydowns. 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 counterparty are representative of an exit price. 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 September 30, 2017 As of December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Collateral-dependent impaired loans (1) $ — $ — $ 19,265 $ — $ — $ 22,019 OREO (2) — — 8,304 — — 8,624 Loans held-for-sale (3) — — 17,508 — — 10,484 Assets held-for-sale (4) — — 9,157 — — 4,075 (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 As of September 30, 2017 , loans held-for-sale consists of 1-4 family mortgage loans, which were originated with the intent to sell. These loans were recorded in the held-for-sale category at the contract price and, accordingly, are classified in level 3 of the fair value hierarchy. As of December 31, 2016 , loans held-for-sale consists of 1-4 family mortgage loans, which were originated with the intent to sell, and a corporate loan. Assets Held-for-Sale Assets held-for-sale as of September 30, 2017 and December 31, 2016 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. 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 September 30, 2017 December 31, 2016 Fair Value Hierarchy Level Carrying Amount Fair Value Carrying Amount Fair Value Assets: Cash and due from banks 1 $ 174,147 $ 174,147 $ 155,055 $ 155,055 Interest-bearing deposits in other banks 2 252,753 252,753 107,093 107,093 Securities held-to-maturity 2 14,638 12,921 22,291 18,212 FHLB and FRB stock 2 69,708 69,708 59,131 59,131 Loans 3 10,299,094 10,048,553 8,172,584 7,973,845 Investment in BOLI 3 279,639 279,639 219,746 219,746 Accrued interest receivable 3 43,697 43,697 34,384 34,384 Other interest-earning assets 3 327 327 834 834 Liabilities: Deposits 2 $ 11,208,497 $ 11,195,159 $ 8,828,603 $ 8,820,572 Borrowed funds 2 700,536 700,536 879,008 879,008 Senior and subordinated debt 2 195,028 194,449 194,603 197,888 Accrued interest payable 2 3,336 3,336 3,416 3,416 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. Short-Term Financial Assets and Liabilities - For financial instruments with a shorter-term or with no stated maturity, prevailing market rates, and limited credit risk, the carrying amounts approximate fair value. Those financial instruments include cash and due from banks, interest-bearing deposits in other banks, accrued interest receivable, and accrued interest payable. Securities Held-to-Maturity - The fair value of securities held-to-maturity is estimated using the present value of expected future cash flows of the remaining maturities of the securities. FHLB and FRB Stock - The carrying amounts approximate fair value as the stock is non-marketable. Loans - Loans includes the FDIC indemnification asset and net loans, which consists of loans held-for-investment, acquired loans, and the allowance for loan losses. The fair value of loans is estimated using the present value of the expected future cash flows of the remaining maturities of the loans. Prepayment assumptions that consider the Company's historical experience and current economic and lending conditions were included. The discount rate was based on the LIBOR yield curve with adjustments for liquidity and credit risk inherent in the loans. Investment in BOLI - The fair value of BOLI approximates the carrying amount as both are based on each policy's respective cash surrender value ("CSV"), which is the amount the Company would receive from the liquidation of these investments. The CSV is derived from monthly reports provided by the managing brokers and is determined using the Company 's initial insurance premium and earnings of the underlying assets, offset by management fees. Other Interest-Earning Assets - The fair value of other interest-earning assets is estimated using the present value of the expected future cash flows of the remaining maturities of the assets. Deposits - The fair values disclosed for demand deposits, savings deposits, NOW accounts, and money market deposits are equal to the amount payable on demand at the reporting date (i.e., their carrying amounts). The fair value for fixed-rate time deposits was estimated using the expected future cash flows discounted based on the LIBOR yield curve, plus or minus the spread associated with current pricing. Borrowed Funds - The fair value of FHLB advances is estimated by discounting the agreements based on maturities using the rates currently offered for FHLB advances of similar remaining maturities adjusted for prepayment penalties that would be incurred if the borrowings were paid off on the measurement date. The carrying amounts of securities sold under agreements to repurchase approximate their fair value due to their short-term nature. Senior and Subordinated Debt - The fair values of senior and subordinated notes are estimated based on quoted market prices of similar instruments. The fair values of junior subordinated debentures are estimated based on quoted market prices of comparable securities when available, or by discounting the expected future cash flows at market interest rates. Commitments to Extend Credit and Letters of Credit - The Company estimated the fair value of lending commitments outstanding to be immaterial based on (i) the limited interest rate exposure of the commitments outstanding due to their variable nature, (ii) the short-term nature of the commitment periods, (iii) termination clauses provided in the agreements, and (iv) the market rate of fees charged.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation – The accompanying unaudited condensed consolidated interim financial statements ("consolidated financial statements") of First Midwest Bancorp, Inc. (the " Company "), a Delaware corporation, were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (" SEC ") for quarterly reports on Form 10-Q and reflect all adjustments that management deems necessary for the fair presentation of the financial position and results of operations for the periods presented. The results of operations for the quarter and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 . 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. The accompanying consolidated financial statements do not include certain information and note disclosures required by GAAP for complete annual financial statements. Therefore, these financial statements should be read in conjunction with the Company 's 2016 Annual Report on Form 10-K (" 2016 10-K"). The Company uses the accrual basis of accounting for financial reporting purposes.
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.
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 Condensed Consolidated Statements of Income from the effective date of the acquisition.
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 consists 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. 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	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, automobile, 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 ( " TDR s" ) – 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 TDR s when the modification is short-term or results in an insignificant delay in payments. The Company 's TDR s 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 TDR s 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 restructured until it is paid in full or charged-off.
Impaired Loans	Impaired Loans – Impaired loans consist of corporate non-accrual loans and TDR s. 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 TDR s, 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/Loan Losses and Reserve for Unfunded Commitments	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 probability of default/loss given default (" 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 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, the economy, changes in interest rates and property values, and the interpretation of loan risk classifications by regulatory authorities.
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.
Recent Accounting Pronouncements	Adopted Accounting Pronouncements Contingent Put and Call Options in Debt Instruments: In March of 2016, the Financial Accounting Standards Board ("FASB") issued final guidance clarifying the requirements for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. Entities are required to apply the guidance to existing debt instruments (or hybrid financial instruments that are determined to have a debt host) using a modified retrospective transition method as of the period of adoption. The adoption of this guidance on January 1, 2017 did not impact the Company 's financial condition, results of operations, or liquidity. Equity Method Accounting: In March of 2016, the FASB issued final guidance to simplify the equity method of accounting. The guidance eliminates the requirement to retrospectively apply equity method accounting in previous periods when an investor initially obtains significant influence over an investee. This guidance is effective for annual and interim periods beginning after December 15, 2016. The adoption of this guidance on January 1, 2017 did not impact the Company 's financial condition, results of operations, or liquidity. Accounting for Employee Share-based Payments: In March of 2016, the FASB issued guidance to simplify the accounting for employee share-based payment transactions. The guidance requires entities to recognize the income tax effects of awards in the income statement when the awards vest or are settled. In addition, the guidance allows entities to repurchase more of an employee's shares than it can under current guidance for tax withholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur. The adoption of this guidance on January 1, 2017 resulted in a $638,000 tax benefit to the provision for income tax expense for the nine months ended September 30, 2017 , recorded in the Company's results of operations. The Company elected to estimate forfeitures, which is consistent with the Company's practice before the adoption of this guidance. Accounting Pronouncements Pending Adoption Revenue from Contracts with Customers: In May of 2014, the FASB issued guidance that requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In March of 2016, the FASB issued an amendment to this guidance to clarify the implementation of guidance on principal versus agent consideration. Additional amendments to clarify the implementation guidance on the identification of performance obligations and licensing were issued in April of 2016 and narrow-scope improvements and practical expedients were issued in May of 2016. The guidance was initially effective for annual and interim reporting periods beginning on or after December 15, 2016 but was deferred to December 15, 2017, and must be applied either retrospectively or using the modified retrospective approach. Early adoption is permitted, but not before the original effective date. The Company's revenue is comprised of net interest income on financial assets and liabilities, which is excluded from the scope of this guidance, and noninterest income. The primary sources of revenue within noninterest income are service charges on deposit accounts, wealth management fees, card-based fees, and merchant servicing fees. Based upon the Company's initial assessment, this guidance is expected to affect how the Company currently presents certain contract costs on a gross basis versus a net basis against the related noninterest income and will result in the expansion of the qualitative disclosures regarding noninterest income. The Company will adopt this guidance on January 1, 2018 using the modified retrospective approach and does not expect the changes in presentation of certain contract costs or the expanded disclosures to have a significant impact on the Company's financial condition, results of operations, or liquidity. The Company is in the process of completing its review of contracts to validate this initial assessment. Amendments to Guidance on Classifying and Measuring Financial Instruments: In January of 2016, the FASB issued guidance that will require entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value. Any changes in fair value will be recognized in net income unless the investments qualify for a new practicability exception. This guidance also requires entities to adjust the fair value disclosures for financial instruments carried at amortized cost from an entry price to an exit price. No changes were made to the guidance for classifying and measuring investments in debt securities and loans. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Leases: In February of 2016, the FASB issued guidance 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. Early adoption is permitted. During 2016, First Midwest Bank (the "Bank") entered into a sale-leaseback transaction that resulted in a deferred gain of $82.5 million , with $76.1 million remaining as of September 30, 2017 . Upon adoption of this guidance, the remaining deferred gain will be recognized immediately as a cumulative-effect adjustment to equity. For additional discussion of the sale-leaseback transaction, see Note 8 " Premises, Furniture, and Equipment ." Management is evaluating the new guidance and the additional impact to the Company 's financial condition, results of operations, or liquidity. Measurement of Credit Losses on Financial Instruments: In June of 2016, the FASB issued guidance 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. Management is evaluating the new guidance and the impact to the Company 's financial condition, results of operations, and liquidity. Classification of Certain Cash Receipts and Cash Payments: In August of 2016, the FASB issued guidance clarifying certain cash flow presentation and classification issues to reduce diversity in practice. This guidance is effective for annual and interim reporting periods beginning on or after December 15, 2017. Early adoption is permitted. Management does not expect the adoption of this guidance will materially impact the Company 's Consolidated Statement of Cash Flows. Income Taxes: In October of 2016, the FASB issued guidance that requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Clarifying the Definition of a Business: In January of 2017, the FASB issued guidance that clarifies the definition of a business to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Accounting for Goodwill Impairment: In January of 2017, the FASB issued guidance 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. Presentation of Defined Benefit Retirement Plan Costs: In March of 2017, the FASB issued guidance that changes how employers that sponsor defined pension and or other postretirement benefit plans present the net periodic benefit cost in the income statement. Employers will present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Other components of net periodic benefit cost will be presented separately from the line item(s) that includes the service cost. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Premium Amortization on Purchased Callable Debt Securities: In March of 2017, the FASB issued guidance 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. 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. Share-based Payment Award Modifications: In May of 2017, the FASB issued guidance to reduce diversity in practice by clarifying when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. This guidance is effective for annual and interim periods beginning after December 15, 2017. 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. Derivatives and Hedging: In August of 2017, the FASB issued guidance to better align the financial reporting related to hedging activities with the economic objectives of those activities and to simplify the application of current hedge accounting guidance. Entities are required to apply the guidance using a modified retrospective method as of the period of adoption. This guidance is effective for annual and interim periods beginning after December 31, 2018. Early adoption is permitted. Management is evaluating the new guidance, but does not expect the adoption of this guidance will materially impact the Company's financial condition, results of operations, or liquidity.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2017
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 Standard and NI Bancshares 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 (Amounts in thousands, except share and per share data) Standard NI Bancshares January 6, 2017 March 8, 2016 Assets Cash and due from banks and interest-bearing deposits in other banks $ 102,149 $ 72,533 Securities available-for-sale 214,107 125,843 Securities held-to-maturity — 1,864 FHLB and FRB stock 3,247 1,549 Loans 1,769,655 396,181 OREO 8,424 2,863 Investment in BOLI 55,629 8,384 Goodwill 339,207 22,174 Other intangible assets 31,072 10,408 Premises, furniture, and equipment 60,286 19,636 Accrued interest receivable and other assets 56,003 16,453 Total assets $ 2,639,779 $ 677,888 Liabilities Noninterest-bearing deposits $ 675,354 $ 130,909 Interest-bearing deposits 1,348,520 464,012 Total deposits 2,023,874 594,921 Borrowed funds — 2,416 Intangible liabilities — 230 Accrued interest payable and other liabilities 35,190 10,239 Total liabilities 2,059,064 607,806 Consideration Paid Common stock (2017 - 21,057,085 shares issued at $25.34 per share, 2016 - 3,042,494 shares issued at $18.059 per share), net of issuance costs 533,590 54,896 Cash paid 47,125 15,186 Total consideration paid 580,715 70,082 $ 2,639,779 $ 677,888
Unaudited Pro Forma Combined Results of Operations	Unaudited Pro Forma Combined Results of Operations (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Total revenues (1) $ 163,241 $ 164,786 $ 482,526 $ 462,962 Net income 38,462 32,589 106,848 85,054 (1) Includes net interest income and total noninterest income.
Summary of Standard Acquired Loans	The following table presents additional detail for loans acquired in the Standard transaction at the acquisition date. Standard Acquired Loans (Dollar amounts in thousands) January 6, 2017 PCI Loans Non-PCI Loans Fair value $ 126,469 $ 1,643,186 Contractually required principal and interest payments 211,931 1,937,060 Best estimate of contractual cash flows not expected to be collected (1) 57,783 100,762 Best estimate of contractual cash flows expected to be collected 154,148 1,836,298 (1) Includes interest payments not expected to be collected due to loan prepayments as well as principal and interest payments not expected to be collected due to customer default.

Securities (Tables)

Securities (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
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 September 30, 2017 As of December 31, 2016 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 42,567 $ 14 $ (77 ) $ 42,504 $ 48,581 $ 26 $ (66 ) $ 48,541 U.S. agency securities 154,666 303 (362 ) 154,607 183,528 519 (410 ) 183,637 Collateralized mortgage obligations ("CMOs") 949,762 459 (12,999 ) 937,222 1,064,130 969 (17,653 ) 1,047,446 Other mortgage-backed securities ("MBSs") 358,746 307 (3,580 ) 355,473 337,139 1,395 (5,879 ) 332,655 Municipal securities 204,571 1,294 (841 ) 205,024 273,319 1,245 (3,718 ) 270,846 Trust-preferred collateralized debt obligations ("CDOs") 45,851 275 (15,300 ) 30,826 47,681 261 (14,682 ) 33,260 Equity securities 7,358 185 (215 ) 7,328 3,206 147 (288 ) 3,065 Total securities available-for-sale $ 1,763,521 $ 2,837 $ (33,374 ) $ 1,732,984 $ 1,957,584 $ 4,562 $ (42,696 ) $ 1,919,450 Securities Held-to-Maturity Municipal securities $ 14,638 $ — $ (1,717 ) $ 12,921 $ 22,291 $ — $ (4,079 ) $ 18,212 Trading Securities $ 20,425 $ 17,920
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 September 30, 2017 As of December 31, 2016 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 42,567 $ 14 $ (77 ) $ 42,504 $ 48,581 $ 26 $ (66 ) $ 48,541 U.S. agency securities 154,666 303 (362 ) 154,607 183,528 519 (410 ) 183,637 Collateralized mortgage obligations ("CMOs") 949,762 459 (12,999 ) 937,222 1,064,130 969 (17,653 ) 1,047,446 Other mortgage-backed securities ("MBSs") 358,746 307 (3,580 ) 355,473 337,139 1,395 (5,879 ) 332,655 Municipal securities 204,571 1,294 (841 ) 205,024 273,319 1,245 (3,718 ) 270,846 Trust-preferred collateralized debt obligations ("CDOs") 45,851 275 (15,300 ) 30,826 47,681 261 (14,682 ) 33,260 Equity securities 7,358 185 (215 ) 7,328 3,206 147 (288 ) 3,065 Total securities available-for-sale $ 1,763,521 $ 2,837 $ (33,374 ) $ 1,732,984 $ 1,957,584 $ 4,562 $ (42,696 ) $ 1,919,450 Securities Held-to-Maturity Municipal securities $ 14,638 $ — $ (1,717 ) $ 12,921 $ 22,291 $ — $ (4,079 ) $ 18,212 Trading Securities $ 20,425 $ 17,920
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 September 30, 2017 As of December 31, 2016 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value Gains Losses Gains Losses Securities Available-for-Sale U.S. treasury securities $ 42,567 $ 14 $ (77 ) $ 42,504 $ 48,581 $ 26 $ (66 ) $ 48,541 U.S. agency securities 154,666 303 (362 ) 154,607 183,528 519 (410 ) 183,637 Collateralized mortgage obligations ("CMOs") 949,762 459 (12,999 ) 937,222 1,064,130 969 (17,653 ) 1,047,446 Other mortgage-backed securities ("MBSs") 358,746 307 (3,580 ) 355,473 337,139 1,395 (5,879 ) 332,655 Municipal securities 204,571 1,294 (841 ) 205,024 273,319 1,245 (3,718 ) 270,846 Trust-preferred collateralized debt obligations ("CDOs") 45,851 275 (15,300 ) 30,826 47,681 261 (14,682 ) 33,260 Equity securities 7,358 185 (215 ) 7,328 3,206 147 (288 ) 3,065 Total securities available-for-sale $ 1,763,521 $ 2,837 $ (33,374 ) $ 1,732,984 $ 1,957,584 $ 4,562 $ (42,696 ) $ 1,919,450 Securities Held-to-Maturity Municipal securities $ 14,638 $ — $ (1,717 ) $ 12,921 $ 22,291 $ — $ (4,079 ) $ 18,212 Trading Securities $ 20,425 $ 17,920
Remaining Contractual Maturity of Securities	Remaining Contractual Maturity of Securities (Dollar amounts in thousands) As of September 30, 2017 Available-for-Sale Held-to-Maturity Amortized Cost Fair Value Amortized Cost Fair Value One year or less $ 97,905 $ 94,691 $ 1,947 $ 1,718 After one year to five years 303,899 293,924 6,065 5,354 After five years to ten years — — 2,243 1,980 After ten years 45,851 44,346 4,383 3,869 Securities that do not have a single contractual maturity date 1,315,866 1,300,023 — — Total $ 1,763,521 $ 1,732,984 $ 14,638 $ 12,921
Securities Available-for-Sale Gains	The following table presents net realized gains on securities available-for-sale for the quarters and nine months ended September 30, 2017 and 2016 . Securities Available-for-Sale Gains (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Gains on sales of securities: Gross realized gains $ 3,197 $ 187 $ 3,481 $ 1,266 Gross realized losses — — — (169 ) Net realized gains on sales of securities 3,197 187 3,481 1,097 Non-cash impairment charges: Other-than-temporary securities impairment ("OTTI") — — — — Net realized gains $ 3,197 $ 187 $ 3,481 $ 1,097
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 September 30, 2017 and December 31, 2016 . Securities in an Unrealized Loss Position (Dollar amounts in thousands) Less Than 12 Months 12 Months or Longer Total Number of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses As of September 30, 2017 Securities Available-for-Sale U.S. treasury securities 16 $ 30,469 $ 51 $ 5,998 $ 26 $ 36,467 $ 77 U.S. agency securities 33 71,538 291 8,241 71 79,779 362 CMOs 195 607,645 7,680 241,930 5,319 849,575 12,999 MBSs 72 262,080 2,851 41,994 729 304,074 3,580 Municipal securities 138 42,951 461 17,045 380 59,996 841 CDOs 7 — — 30,015 15,300 30,015 15,300 Equity securities 2 — — 6,833 215 6,833 215 Total 463 $ 1,014,683 $ 11,334 $ 352,056 $ 22,040 $ 1,366,739 $ 33,374 Securities Held-to-Maturity Municipal securities 10 $ — $ — $ 12,921 $ 1,717 $ 12,921 $ 1,717 As of December 31, 2016 Securities Available-for-Sale U.S. treasury securities 16 $ 33,505 $ 61 $ 3,995 $ 5 $ 37,500 $ 66 U.S. agency securities 28 62,064 364 11,814 46 73,878 410 CMOs 194 523,233 10,309 411,758 7,344 934,991 17,653 MBSs 68 221,174 4,726 77,780 1,154 298,954 5,880 Municipal securities 380 133,957 3,059 29,280 659 163,237 3,718 CDOs 7 — — 30,592 14,682 30,592 14,682 Equity securities 2 404 201 2,319 86 2,723 287 Total 695 $ 974,337 $ 18,720 $ 567,538 $ 23,976 $ 1,541,875 $ 42,696 Securities Held-to-Maturity Municipal securities 14 $ — $ — $ 18,212 $ 4,079 $ 18,212 $ 4,079

Loans (Tables)

Loans (Tables)	9 Months Ended
	Sep. 30, 2017
Loans and Leases Receivable Disclosure [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 September 30, December 31, Commercial and industrial $ 3,462,612 $ 2,827,658 Agricultural 437,721 389,496 Commercial real estate: Office, retail, and industrial 1,960,367 1,581,967 Multi-family 711,101 614,052 Construction 545,666 451,540 Other commercial real estate 1,391,241 979,528 Total commercial real estate 4,608,375 3,627,087 Total corporate loans 8,508,708 6,844,241 Home equity 847,209 747,983 1-4 family mortgages 711,607 423,922 Installment 322,768 237,999 Total consumer loans 1,881,584 1,409,904 Total loans $ 10,390,292 $ 8,254,145 Deferred loan fees included in total loans $ 5,189 $ 3,838 Overdrawn demand deposits included in total loans 6,616 7,836
Schedule Of Loans Sold	The following table presents loan sales for the quarters and nine months ended September 30, 2017 and 2016 . Loan Sales (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Corporate loan sales Proceeds from sales $ 11,833 $ 12,223 $ 46,770 $ 36,082 Less book value of loans sold 11,512 11,828 45,752 34,718 Net gains on corporate loan sales (1) 321 395 1,018 1,364 1-4 family mortgage loan sales Proceeds from sales $ 73,889 $ 110,167 190,544 202,932 Less book value of loans sold 72,149 107,255 186,208 198,024 Net gains on 1-4 family mortgage loan sales (2) 1,740 2,912 4,336 4,908 Total net gains on loan sales $ 2,061 $ 3,307 $ 5,354 $ 6,272 (1) Net gains on corporate loan sales are included in other service charges, commissions, and fees in the Condensed Consolidated Statements of Income. (2) Net gains on 1-4 family mortgage loan sales are included in mortgage banking income in the Condensed Consolidated Statements of Income.

Acquired and Covered Loans (Tab

Acquired and Covered Loans (Tables)	9 Months Ended
	Sep. 30, 2017
Acquired Loans [Abstract]
Acquired Loans	The following table presents the carrying amount of acquired and covered PCI and non-PCI loans as of September 30, 2017 and December 31, 2016 . Acquired and Covered Loans (1) (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 PCI Non-PCI Total PCI Non-PCI Total Acquired loans $ 150,405 $ 1,694,032 $ 1,844,437 $ 53,772 $ 613,339 $ 667,111 Covered loans 6,871 12,474 19,345 7,895 15,379 23,274 Total acquired and covered loans $ 157,276 $ 1,706,506 $ 1,863,782 $ 61,667 $ 628,718 $ 690,385 (1) Included in loans in the Consolidated Statements of Condition.
FDIC Indemnification Asset Roll Forward	Rollforwards of the carrying value of the FDIC indemnification asset for the quarters and nine months ended September 30, 2017 and 2016 are presented in the following table. Changes in the FDIC Indemnification Asset (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 3,918 $ 5,171 $ 4,522 $ 3,903 Amortization (302 ) (302 ) (906 ) (884 ) Change in expected reimbursements from the FDIC for changes in expected credit losses (123 ) (228 ) (653 ) (487 ) Net payments to the FDIC 123 191 653 2,300 Ending balance $ 3,616 $ 4,832 $ 3,616 $ 4,832
Schedule Of 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) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balances $ 39,870 $ 25,082 $ 19,385 $ 24,912 Additions — — 27,316 3,981 Accretion (4,263 ) (2,763 ) (12,106 ) (6,612 ) Other (1) 478 (1,012 ) 1,490 (974 ) Ending balance $ 36,085 $ 21,307 $ 36,085 $ 21,307 (1) Increases represent a rise in the expected future cash flows to be collected over the remaining estimated life of the underlying portfolio while decreases result from the resolution of certain loans occurring earlier than anticipated.

Past Due Loans, Allowance For30

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 . 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 (2) 90 Days or More Past Due, Still Accruing Interest As of September 30, 2017 Commercial and industrial $ 3,444,056 $ 14,536 $ 4,020 $ 18,556 $ 3,462,612 $ 41,504 $ 1,166 Agricultural 436,693 325 703 1,028 437,721 380 335 Commercial real estate: Office, retail, and industrial 1,950,010 4,411 5,946 10,357 1,960,367 12,221 — Multi-family 707,959 3,013 129 3,142 711,101 153 129 Construction 545,119 29 518 547 545,666 146 374 Other commercial real estate 1,387,969 1,356 1,916 3,272 1,391,241 2,239 349 Total commercial real estate 4,591,057 8,809 8,509 17,318 4,608,375 14,759 852 Total corporate loans 8,471,806 23,670 13,232 36,902 8,508,708 56,643 2,353 Home equity 840,966 3,729 2,514 6,243 847,209 5,529 44 1-4 family mortgages 707,498 3,714 395 4,109 711,607 3,004 — Installment 320,210 2,116 442 2,558 322,768 — 442 Total consumer loans 1,868,674 9,559 3,351 12,910 1,881,584 8,533 486 Total loans $ 10,340,480 $ 33,229 $ 16,583 $ 49,812 $ 10,390,292 $ 65,176 $ 2,839 As of December 31, 2016 Commercial and industrial $ 2,816,442 $ 6,426 $ 4,790 $ 11,216 $ 2,827,658 $ 29,938 $ 374 Agricultural 388,596 — 900 900 389,496 181 736 Commercial real estate: Office, retail, and industrial 1,564,007 5,327 12,633 17,960 1,581,967 17,277 1,129 Multi-family 612,446 858 748 1,606 614,052 311 604 Construction 450,927 332 281 613 451,540 286 — Other commercial real estate 974,575 1,307 3,646 4,953 979,528 2,892 1,526 Total commercial real estate 3,601,955 7,824 17,308 25,132 3,627,087 20,766 3,259 Total corporate loans 6,806,993 14,250 22,998 37,248 6,844,241 50,885 4,369 Home equity 740,919 4,545 2,519 7,064 747,983 5,465 109 1-4 family mortgages 420,264 2,652 1,006 3,658 423,922 2,939 272 Installment 236,264 1,476 259 1,735 237,999 — 259 Total consumer loans 1,397,447 8,673 3,784 12,457 1,409,904 8,404 640 Total loans $ 8,204,440 $ 22,923 $ 26,782 $ 49,705 $ 8,254,145 $ 59,289 $ 5,009 (1) PCI loans with an accretable yield are considered current. (2) Includes PCI loans of $239,000 and $681,000 as of September 30, 2017 and December 31, 2016 , respectively, which no longer have an accretable yield as estimates of expected future cash flows have decreased since the acquisition due to credit deterioration.
Allowance for Credit Losses on Financing Receivables	A rollforward of the allowance for credit losses by portfolio segment for the quarters and nine months ended September 30, 2017 and 2016 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 Quarter ended September 30, 2017 Beginning balance $ 46,271 $ 15,008 $ 2,919 $ 4,094 $ 7,479 $ 16,600 $ 1,000 $ 93,371 Charge-offs (8,935 ) (14 ) — 6 (6 ) (1,617 ) — (10,566 ) Recoveries 698 1,825 2 19 25 331 — 2,900 Net charge-offs (8,237 ) 1,811 2 25 19 (1,286 ) — (7,666 ) Provision for loan losses and other 13,994 (5,129 ) (296 ) 161 (257 ) 1,636 — 10,109 Ending balance $ 52,028 $ 11,690 $ 2,625 $ 4,280 $ 7,241 $ 16,950 $ 1,000 $ 95,814 Quarter ended September 30, 2016 Beginning balance $ 40,084 $ 12,985 $ 2,933 $ 2,239 $ 7,492 $ 14,372 $ 1,400 $ 81,505 Charge-offs (1,760 ) (2,193 ) — — (509 ) (1,488 ) — (5,950 ) Recoveries 615 42 69 9 94 326 — 1,155 Net charge-offs (1,145 ) (2,151 ) 69 9 (415 ) (1,162 ) — (4,795 ) Provision for loan losses and other 3,579 3,019 1,048 916 1,490 (54 ) (400 ) 9,598 Ending balance $ 42,518 $ 13,853 $ 4,050 $ 3,164 $ 8,567 $ 13,156 $ 1,000 $ 86,308 Nine months ended September 30, 2017 Beginning balance $ 40,709 $ 17,595 $ 3,261 $ 3,444 $ 7,739 $ 13,335 $ 1,000 $ 87,083 Charge-offs (15,966 ) (141 ) — (38 ) (721 ) (4,837 ) — (21,703 ) Recoveries 2,764 2,808 36 258 205 1,097 — 7,168 Net charge-offs (13,202 ) 2,667 36 220 (516 ) (3,740 ) — (14,535 ) Provision for loan losses and other 24,521 (8,572 ) (672 ) 616 18 7,355 — 23,266 Ending balance $ 52,028 $ 11,690 $ 2,625 $ 4,280 $ 7,241 $ 16,950 $ 1,000 $ 95,814 Nine months ended September 30, 2016 Beginning balance $ 37,074 $ 13,124 $ 2,469 $ 1,440 $ 6,109 $ 13,414 $ 1,225 $ 74,855 Charge-offs (5,684 ) (4,358 ) (288 ) (134 ) (2,833 ) (3,975 ) — (17,272 ) Recoveries 1,693 153 95 44 314 975 — 3,274 Net charge-offs (3,991 ) (4,205 ) (193 ) (90 ) (2,519 ) (3,000 ) — (13,998 ) Provision for loan losses and other 9,435 4,934 1,774 1,814 4,977 2,742 (225 ) 25,451 Ending balance $ 42,518 $ 13,853 $ 4,050 $ 3,164 $ 8,567 $ 13,156 $ 1,000 $ 86,308
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 September 30, 2017 and December 31, 2016 . 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 September 30, 2017 Commercial, industrial, and agricultural $ 39,121 $ 3,835,995 $ 25,217 $ 3,900,333 $ 3,408 $ 48,107 $ 513 $ 52,028 Commercial real estate: Office, retail, and industrial 11,211 1,932,332 16,824 1,960,367 9 10,291 1,390 11,690 Multi-family 395 696,490 14,216 711,101 — 2,524 101 2,625 Construction — 532,016 13,650 545,666 — 4,060 220 4,280 Other commercial real estate 656 1,325,280 65,305 1,391,241 — 6,126 1,115 7,241 Total commercial real estate 12,262 4,486,118 109,995 4,608,375 9 23,001 2,826 25,836 Total corporate loans 51,383 8,322,113 135,212 8,508,708 3,417 71,108 3,339 77,864 Consumer — 1,859,520 22,064 1,881,584 — 15,684 1,266 16,950 Reserve for unfunded commitments — — — — — 1,000 — 1,000 Total loans $ 51,383 $ 10,181,633 $ 157,276 $ 10,390,292 $ 3,417 $ 87,792 $ 4,605 $ 95,814 As of December 31, 2016 Commercial, industrial, and agricultural $ 24,645 $ 3,189,327 $ 3,182 $ 3,217,154 $ 507 $ 39,554 $ 648 $ 40,709 Commercial real estate: Office, retail, and industrial 16,287 1,553,234 12,446 1,581,967 — 16,148 1,447 17,595 Multi-family 398 601,429 12,225 614,052 — 3,059 202 3,261 Construction 34 447,058 4,448 451,540 — 3,280 164 3,444 Other commercial real estate 1,286 965,900 12,342 979,528 18 6,613 1,108 7,739 Total commercial real estate 18,005 3,567,621 41,461 3,627,087 18 29,100 2,921 32,039 Total corporate loans 42,650 6,756,948 44,643 6,844,241 525 68,654 3,569 72,748 Consumer — 1,392,880 17,024 1,409,904 — 12,210 1,125 13,335 Reserve for unfunded commitments — — — — — 1,000 — 1,000 Total loans $ 42,650 $ 8,149,828 $ 61,667 $ 8,254,145 $ 525 $ 81,864 $ 4,694 $ 87,083
Impaired Financing Receivables	The following table presents the average recorded investment and interest income recognized on impaired loans by class for the quarters and nine months ended September 30, 2017 and 2016 . PCI loans are excluded from this disclosure. Average Recorded Investment and Interest Income Recognized on Impaired Loans by Class (Dollar amounts in thousands) Quarters Ended September 30, 2017 2016 Average Interest Income Recognized (1) Average Interest Income Recognized (1) Commercial and industrial $ 44,682 $ 368 $ 7,829 $ 57 Agricultural 140 — — — Commercial real estate: Office, retail, and industrial 12,496 — 16,101 3 Multi-family 396 — 399 11 Construction — — 34 — Other commercial real estate 1,415 — 2,561 — Total commercial real estate 14,307 — 19,095 14 Total impaired loans $ 59,129 $ 368 $ 26,924 $ 71 Nine Months Ended September 30, 2017 2016 Average Interest (1) Average Interest (1) Commercial and industrial $ 32,765 $ 924 $ 5,312 $ 107 Agricultural 348 — — — Commercial real estate: Office, retail, and industrial 13,680 262 12,012 80 Multi-family 396 28 500 12 Construction 9 136 70 — Other commercial real estate 1,652 20 3,190 72 Total commercial real estate 15,737 446 15,772 164 Total impaired loans $ 48,850 $ 1,370 $ 21,084 $ 271 (1) Recorded using the cash basis of accounting. The following table presents loans individually evaluated for impairment by class of loan as of September 30, 2017 and December 31, 2016 . PCI loans are excluded from this disclosure. Impaired Loans Individually Evaluated by Class (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 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 $ 24,688 $ 14,433 $ 47,700 $ 3,408 $ 11,579 $ 13,066 $ 29,514 $ 507 Agricultural — — — — — — — — Commercial real estate: Office, retail, and industrial 7,146 4,065 14,480 9 16,287 — 21,057 — Multi-family 395 — 395 — 398 — 398 — Construction — — — — 34 — 34 — Other commercial real estate 656 — 754 — 1,016 270 2,141 18 Total commercial real estate 8,197 4,065 15,629 9 17,735 270 23,630 18 Total impaired loans individually evaluated for impairment $ 32,885 $ 18,498 $ 63,329 $ 3,417 $ 29,314 $ 13,336 $ 53,144 $ 525
Financing Receivable Credit Quality Indicators	The following tables present credit quality indicators by class for corporate and consumer loans, as of September 30, 2017 and December 31, 2016 . Corporate Credit Quality Indicators by Class (Dollar amounts in thousands) Pass Special Mention (1) (4) Substandard (2) (4) Non-accrual (3) Total As of September 30, 2017 Commercial and industrial $ 3,286,087 $ 72,491 $ 62,530 $ 41,504 $ 3,462,612 Agricultural 417,612 13,310 6,419 380 437,721 Commercial real estate: Office, retail, and industrial 1,877,165 25,919 45,062 12,221 1,960,367 Multi-family 703,659 5,433 1,856 153 711,101 Construction 525,097 9,113 11,310 146 545,666 Other commercial real estate 1,334,385 32,693 21,924 2,239 1,391,241 Total commercial real estate 4,440,306 73,158 80,152 14,759 4,608,375 Total corporate loans $ 8,144,005 $ 158,959 $ 149,101 $ 56,643 $ 8,508,708 As of December 31, 2016 Commercial and industrial $ 2,638,833 $ 92,340 $ 66,547 $ 29,938 $ 2,827,658 Agricultural 366,382 17,039 5,894 181 389,496 Commercial real estate: Office, retail, and industrial 1,491,170 34,007 39,513 17,277 1,581,967 Multi-family 607,342 4,370 2,029 311 614,052 Construction 438,946 111 12,197 286 451,540 Other commercial real estate 951,284 11,808 13,544 2,892 979,528 Total commercial real estate 3,488,742 50,296 67,283 20,766 3,627,087 Total corporate loans $ 6,493,957 $ 159,675 $ 139,724 $ 50,885 $ 6,844,241 (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 well-defined weaknesses 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 well-defined weaknesses that may jeopardize the liquidation of the debt or result in a loss if the deficiencies are not corrected. (4) Total special mention and substandard loans includes accruing TDR s of $664,000 as of September 30, 2017 and $834,000 as of December 31, 2016 . Consumer Credit Quality Indicators by Class (Dollar amounts in thousands) Performing Non-accrual Total As of September 30, 2017 Home equity $ 841,680 $ 5,529 $ 847,209 1-4 family mortgages 708,603 3,004 711,607 Installment 322,768 — 322,768 Total consumer loans $ 1,873,051 $ 8,533 $ 1,881,584 As of December 31, 2016 Home equity $ 742,518 $ 5,465 $ 747,983 1-4 family mortgages 420,983 2,939 423,922 Installment 237,999 — 237,999 Total consumer loans $ 1,401,500 $ 8,404 $ 1,409,904
Troubled Debt Restructuring Activity Rollforward	The table below presents TDR s by class as of September 30, 2017 and December 31, 2016 . See Note 1, "Summary of Significant Accounting Policies," for the accounting policy for TDR s. TDR s by Class (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 Accruing Non-accrual (1) Total Accruing Non-accrual (1) Total Commercial and industrial $ 269 $ 22,780 $ 23,049 $ 281 $ 150 $ 431 Agricultural — — — — — — Commercial real estate: Office, retail, and industrial — 4,512 4,512 155 4,733 4,888 Multi-family 577 153 730 586 168 754 Construction — — — — — — Other commercial real estate 194 — 194 268 48 316 Total commercial real estate 771 4,665 5,436 1,009 4,949 5,958 Total corporate loans 1,040 27,445 28,485 1,290 5,099 6,389 Home equity 88 755 843 177 820 997 1-4 family mortgages 685 462 1,147 824 378 1,202 Installment — — — — — — Total consumer loans 773 1,217 1,990 1,001 1,198 2,199 Total loans $ 1,813 $ 28,662 $ 30,475 $ 2,291 $ 6,297 $ 8,588 (1) These TDR s are included in non-accrual loans in the preceding tables. The following table presents a summary of loans that were restructured during the quarter and nine months ended September 30, 2017 . There were no material restructures during the quarter and nine months ended September 30, 2016 . 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 Quarter ended September 30, 2017 Commercial and industrial 10 $ 25,811 $ 196 $ — $ 1,736 $ 24,271 Office, retail, and industrial 2 3,656 — — — 3,656 Total TDRs restructured during the period 12 $ 29,467 $ 196 $ — $ 1,736 $ 27,927 Nine months ended September 30, 2017 Commercial and industrial 12 $ 26,733 $ 196 $ — $ 1,736 $ 25,193 Office, retail, and industrial 2 3,656 — — — 3,656 Total TDRs restructured during the period 14 $ 30,389 $ 196 $ — $ 1,736 $ 28,849 A rollforward of the carrying value of TDR s for the quarters and nine months ended September 30, 2017 and 2016 is presented in the following table. TDR Rollforward (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Accruing Beginning balance $ 2,029 $ 2,491 $ 2,291 $ 2,743 Additions 14,897 — 15,819 — Net payments received (1,798 ) (22 ) (1,905 ) (91 ) Net transfers to non-accrual (13,315 ) (101 ) (14,392 ) (284 ) Ending balance 1,813 2,368 1,813 2,368 Non-accrual Beginning balance 3,036 1,690 6,297 2,324 Additions 14,570 — 14,570 — Net payments received (127 ) (31 ) (4,352 ) (609 ) Charge-offs (2,132 ) (170 ) (2,245 ) (409 ) Net transfers from accruing 13,315 101 14,392 284 Ending balance 28,662 1,590 28,662 1,590 Total TDRs $ 30,475 $ 3,958 $ 30,475 $ 3,958

Premises, Furniture, and Equi31

Premises, Furniture, and Equipment (Tables)	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Summary of 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 September 30, December 31, Land $ 30,267 $ 18,304 Premises 119,325 94,369 Furniture and equipment 114,547 105,859 Total cost 264,139 218,532 Accumulated depreciation (142,001 ) (140,030 ) Net book value of premises, furniture, and equipment 122,138 78,502 Assets held-for-sale 9,157 4,075 Total premises, furniture, and equipment $ 131,295 $ 82,577
Schedule of Future Minimum Lease Payments for Operating Leases	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 as of September 30, 2017 . Future Minimum Operating Lease Payments (Dollar amounts in thousands) Total One year or less $ 19,298 After one year to two years 17,737 After two years to three years 17,008 After three years to four years 16,815 After four years to five years 16,550 After five years 120,048 Total minimum lease payments $ 207,456
Scheduled Accretion of Operating Lease Intangible	The following table presents the remaining scheduled accretion of the intangible liability by year. Scheduled Accretion of Operating Lease Intangible (Dollar amounts in thousands) Total One year or less $ 1,011 After one year to two years 742 After two years to three years 648 After three years to four years 648 After four years to five years 648 After five years 3,511 Total accretion $ 7,208
Schedule Of Net Operating Lease Expense	The following table presents net operating lease expense for the quarters and nine months ended September 30, 2017 and 2016 . Net Operating Lease Expense (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Lease expense charged to operations $ 4,747 $ 2,229 $ 14,027 $ 5,729 Accretion of operating lease intangible (1) (295 ) (295 ) (885 ) (876 ) Accretion of deferred gain on sale-leaseback transaction (1) (1,463 ) — (4,409 ) — Rental income from premises leased to others (1) (171 ) (118 ) (521 ) (404 ) Net operating lease expense $ 2,818 $ 1,816 $ 8,212 $ 4,449 (1) Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income.

Goodwill and Other Intangible32

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table presents changes in the carrying amount of goodwill for the quarters and nine months ended September 30, 2017 and 2016 . Changes in the Carrying Amount of Goodwill (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 691,527 $ 341,513 $ 340,879 $ 319,007 Acquisitions (46 ) (756 ) 350,602 21,750 Ending balance $ 691,481 $ 340,757 $ 691,481 $ 340,757
Schedule of Finite-Lived Intangible Assets	Other Intangible Assets (Dollar amounts in thousands) Nine Months Ended September 30, 2017 2016 Gross Accumulated Amortization Net Gross Accumulated Amortization Net Beginning balance $ 58,959 $ 32,962 $ 25,997 $ 48,550 $ 28,280 $ 20,270 Additions 39,017 — 39,017 10,409 — 10,409 Amortization expense — 6,059 (6,059 ) — 3,475 (3,475 ) Ending balance $ 97,976 $ 39,021 $ 58,955 $ 58,959 $ 31,755 $ 27,204
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Scheduled Amortization of Other Intangible Assets (Dollar amounts in thousands) Total Year Ending September 30, 2018 $ 7,173 2019 7,083 2020 7,036 2021 6,970 2022 6,898 2023 and thereafter 23,795 Total $ 58,955

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2017
Deposits [Abstract]
Schedule Of Deposits	The following table presents the Company's deposits by type. Summary of Deposits (Dollar amounts in thousands) As of September 30, December 31, Demand deposits $ 3,580,922 $ 2,766,748 Savings deposits 2,022,717 1,615,833 NOW accounts 2,048,893 1,675,421 Money market deposits 1,969,865 1,577,316 Time deposits less than $100,000 888,238 755,558 Time deposits greater than $100,000 697,862 437,727 Total deposits $ 11,208,497 $ 8,828,603

Borrowed Funds (Tables)

Borrowed Funds (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, December 31, Securities sold under agreements to repurchase $ 110,536 $ 129,008 FHLB advances 590,000 750,000 Total borrowed funds $ 700,536 $ 879,008

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The table below displays the calculation of basic and diluted earnings per common share (" EPS "). Basic and Diluted EPS (Amounts in thousands, except per share data) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Net income $ 38,235 $ 28,402 $ 96,040 $ 71,631 Net income applicable to non-vested restricted shares (340 ) (324 ) (910 ) (826 ) Net income applicable to common shares $ 37,895 $ 28,078 $ 95,130 $ 70,805 Weighted-average common shares outstanding: Weighted-average common shares outstanding (basic) 101,752 80,396 101,307 79,589 Dilutive effect of common stock equivalents 20 13 20 13 Weighted-average diluted common shares outstanding 101,772 80,409 101,327 79,602 Basic EPS $ 0.37 $ 0.35 $ 0.94 $ 0.89 Diluted EPS $ 0.37 $ 0.35 $ 0.94 $ 0.89 Anti-dilutive shares not included in the computation of diluted EPS (1) 190 454 242 510 (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.

Derivative Instruments and He36

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Interest Rate Derivatives	Fair Value Hedges (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Gross notional amount outstanding $ 5,583 $ 5,958 Derivative liability fair value (146 ) (282 ) Weighted-average interest rate received 3.23 % 2.63 % Weighted-average interest rate paid 5.96 % 5.96 % Weighted-average maturity (in years) 1.10 1.84 Fair value of derivative (1) $ 157 $ 296 (1) This amount represents the fair value if credit risk related contingent features were triggered. Cash Flow Hedges (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Gross notional amount outstanding $ 1,960,000 $ 1,470,000 Derivative asset fair value 3,234 5,402 Derivative liability fair value (6,729 ) (7,390 ) Weighted-average interest rate received 1.55 % 1.37 % Weighted-average interest rate paid 1.51 % 1.11 % Weighted-average maturity (in years) 2.50 2.83
Schedule of Derivative Instruments	Other Derivative Instruments (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Gross notional amount outstanding $ 2,463,967 $ 1,656,612 Derivative asset fair value 18,268 13,478 Derivative liability fair value (14,443 ) (13,478 ) Fair value of derivative (1) 14,704 13,753 (1) This amount represents the fair value if credit risk related contingent features were triggered.
Offsetting Assets	The following table presents the fair value of the Company's derivatives and offsetting positions as of September 30, 2017 and December 31, 2016 . Fair Value of Offsetting Derivatives (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 Assets Liabilities Assets Liabilities Gross amounts recognized $ 21,502 $ 21,318 $ 18,880 $ 21,150 Less: amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition (1) 21,502 21,318 18,880 21,150 Gross amounts not offset in the Consolidated Statements of Financial Condition: Offsetting derivative positions (16,557 ) (16,557 ) (10,889 ) (10,889 ) Cash collateral pledged — (4,761 ) — (10,261 ) Net credit exposure $ 4,945 $ — $ 7,991 $ — (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 September 30, 2017 and December 31, 2016 . Fair Value of Offsetting Derivatives (Dollar amounts in thousands) As of September 30, 2017 As of December 31, 2016 Assets Liabilities Assets Liabilities Gross amounts recognized $ 21,502 $ 21,318 $ 18,880 $ 21,150 Less: amounts offset in the Consolidated Statements of Financial Condition — — — — Net amount presented in the Consolidated Statements of Financial Condition (1) 21,502 21,318 18,880 21,150 Gross amounts not offset in the Consolidated Statements of Financial Condition: Offsetting derivative positions (16,557 ) (16,557 ) (10,889 ) (10,889 ) Cash collateral pledged — (4,761 ) — (10,261 ) Net credit exposure $ 4,945 $ — $ 7,991 $ — (1) Included in other assets or other liabilities in the Consolidated Statements of Financial Condition.

Commitments, Guarantees, and 37

Commitments, Guarantees, and Contingent Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments Disclosure	Contractual or Notional Amounts of Financial Instruments (Dollar amounts in thousands) As of September 30, 2017 December 31, 2016 Commitments to extend credit: Commercial, industrial, and agricultural $ 1,739,259 $ 1,522,152 Commercial real estate 322,705 397,423 Home equity 512,560 426,384 Other commitments (1) 246,609 214,943 Total commitments to extend credit $ 2,821,133 $ 2,560,902 Letters of credit $ 132,990 $ 100,430 (1) Other commitments includes installment and overdraft protection program commitments.

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 As of December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets: Trading securities: Money market funds $ 1,738 $ — $ — $ 1,645 $ — $ — Mutual funds 18,687 — — 16,275 — — Total trading securities 20,425 — — 17,920 — — Securities available-for-sale: U.S. treasury securities 42,504 — — 48,541 — — U.S. agency securities — 154,607 — — 183,637 — CMOs — 937,222 — — 1,047,446 — MBSs — 355,473 — — 332,655 — Municipal securities — 205,024 — — 270,846 — CDOs — — 30,826 — — 33,260 Equity securities — 7,328 — — 3,065 — Total securities available-for-sale 42,504 1,659,654 30,826 48,541 1,837,649 33,260 Mortgage servicing rights ("MSRs") (1) — — 5,766 — — 6,120 Derivative assets (1) — 21,502 — — 18,880 — Liabilities: Derivative liabilities (2) $ — $ 21,318 $ — $ — $ 21,150 $ — (1) Included in other assets in the Consolidated Statements of Financial Condition. (2) Included in other liabilities in the Consolidated Statements of Financial Condition.
Significant Unobservable Inputs Used in the Valuation of CDOs	The following table presents the ranges of significant, unobservable inputs used by the Company to determine the fair value of MSR s as of September 30, 2017 and December 31, 2016 . Significant Unobservable Inputs Used in the Valuation of MSR s As of September 30, 2017 December 31, 2016 Prepayment speed 8.8 % - 26.2% 7.7 % - 22.8% Maturity (months) 7 - 91 12 - 103 Discount rate 9.5 % - 13.0% 9.5 % - 13.0% The following table presents the ranges of significant, unobservable inputs calculated using the weighted-average of the Issuers used by the Company as of September 30, 2017 and December 31, 2016. Significant Unobservable Inputs Used in the Valuation of CDOs As of September 30, 2017 December 31, 2016 Probability of prepayment 0.0 % - 11.4% 0.0 % - 10.9% Probability of default 16.5 % - 44.8% 16.7 % - 46.8% Loss given default 93.4 % - 99.2% 93.3 % - 98.9% Probability of deferral cure 0.0 % - 100.0% 7.6 % - 100.0%
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	A rollforward of the carrying value of CDOs for the quarters and nine months ended September 30, 2017 and 2016 is presented in the following table. Carrying Value of CDOs (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 33,454 $ 30,431 $ 33,260 $ 31,529 Change in other comprehensive income (1) (739 ) 1,794 (604 ) 764 Other (1,889 ) (326 ) (1,830 ) (394 ) Ending balance $ 30,826 $ 31,899 $ 30,826 $ 31,899 (1) Included in unrealized holding gains in the Consolidated Statements of Comprehensive Income. During the third quarter of 2017, three CDOs with carrying values totaling $1.9 million were sold at gains.
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 MSR s as of September 30, 2017 and December 31, 2016 . Significant Unobservable Inputs Used in the Valuation of MSR s As of September 30, 2017 December 31, 2016 Prepayment speed 8.8 % - 26.2% 7.7 % - 22.8% Maturity (months) 7 - 91 12 - 103 Discount rate 9.5 % - 13.0% 9.5 % - 13.0% The following table presents the ranges of significant, unobservable inputs calculated using the weighted-average of the Issuers used by the Company as of September 30, 2017 and December 31, 2016. Significant Unobservable Inputs Used in the Valuation of CDOs As of September 30, 2017 December 31, 2016 Probability of prepayment 0.0 % - 11.4% 0.0 % - 10.9% Probability of default 16.5 % - 44.8% 16.7 % - 46.8% Loss given default 93.4 % - 99.2% 93.3 % - 98.9% Probability of deferral cure 0.0 % - 100.0% 7.6 % - 100.0%
Schedule of Servicing Assets at Fair Value	A rollforward of the carrying value of MSR s for the quarters and nine months ended September 30, 2017 and 2016 is presented in the following table. Carrying Value of MSR s (Dollar amounts in thousands) Quarters Ended Nine Months Ended 2017 2016 2017 2016 Beginning balance $ 5,925 $ 4,938 $ 6,120 $ 1,853 Additions from acquisition — — — 3,092 New MSRs 161 581 522 928 Total losses included in earnings (1) : Changes in valuation inputs and assumptions (121 ) (205 ) (209 ) (377 ) Other changes in fair value (2) (199 ) (238 ) (667 ) (420 ) Ending balance $ 5,766 $ 5,076 $ 5,766 $ 5,076 Contractual servicing fees earned (1) $ 379 $ 373 $ 1,158 $ 922 (1) Included in mortgage banking income in the Condensed Consolidated Statements of Income and related to assets held as of September 30, 2017 and 2016 . (2) Primarily represents changes in expected future cash flows due to payoffs and paydowns.
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 September 30, 2017 As of December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Collateral-dependent impaired loans (1) $ — $ — $ 19,265 $ — $ — $ 22,019 OREO (2) — — 8,304 — — 8,624 Loans held-for-sale (3) — — 17,508 — — 10,484 Assets held-for-sale (4) — — 9,157 — — 4,075 (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 September 30, 2017 December 31, 2016 Fair Value Hierarchy Level Carrying Amount Fair Value Carrying Amount Fair Value Assets: Cash and due from banks 1 $ 174,147 $ 174,147 $ 155,055 $ 155,055 Interest-bearing deposits in other banks 2 252,753 252,753 107,093 107,093 Securities held-to-maturity 2 14,638 12,921 22,291 18,212 FHLB and FRB stock 2 69,708 69,708 59,131 59,131 Loans 3 10,299,094 10,048,553 8,172,584 7,973,845 Investment in BOLI 3 279,639 279,639 219,746 219,746 Accrued interest receivable 3 43,697 43,697 34,384 34,384 Other interest-earning assets 3 327 327 834 834 Liabilities: Deposits 2 $ 11,208,497 $ 11,195,159 $ 8,828,603 $ 8,820,572 Borrowed funds 2 700,536 700,536 879,008 879,008 Senior and subordinated debt 2 195,028 194,449 194,603 197,888 Accrued interest payable 2 3,336 3,336 3,416 3,416

Recent Accounting Pronounceme39

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Share-based compensation tax benefit	$ 638
Deferred gain, net	$ 76,100	$ 82,500

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) $ / shares in Units, $ in Thousands

Jan. 06, 2017USD ($)$ / sharesshares

Mar. 08, 2016USD ($)retail_branchshares

Sep. 30, 2017USD ($)

Sep. 30, 2016USD ($)

Sep. 30, 2017USD ($)

Sep. 30, 2016USD ($)

Dec. 31, 2017USD ($)

Jun. 30, 2017USD ($)

Feb. 28, 2017USD ($)

Dec. 31, 2016USD ($)

Jun. 30, 2016USD ($)

Dec. 31, 2015USD ($)

Business Acquisition [Line Items]

Goodwill

$ 691,481

$ 340,757

$ 691,481

$ 340,757

$ 691,527

$ 340,879

$ 341,513

$ 319,007

Acquisition and integration related expenses

384

$ 1,172

20,123

$ 6,810

Standard Bancshares, Inc.

Business Acquisition [Line Items]

Fixed exchange ratio (in Shares) | shares

0.4350

Consideration transferred

$ 580,715

Common stock, shares issued (in Shares) | shares

21,057,085

Cash paid

$ 47,125

Goodwill

$ 339,207

Acquisition and integration related expenses

$ 384

$ 19,100

Premier Asset Management LLC

Business Acquisition [Line Items]

Assets under management acquired

$ 550,000

NI Bancshares Corporation

Business Acquisition [Line Items]

Consideration transferred

$ 70,082

Common stock, shares issued (in Shares) | shares

3,042,494

Cash paid

$ 15,186

Goodwill

$ 22,174

Number of retail branches acquired | retail_branch

10

Minimum value of trust assets under management acquired

$ 700,000

First Midwest Bancorp, Inc

Business Acquisition [Line Items]

Share price (in Dollars per share) | $ / shares

$ 25.34

Standard Bancshares, Inc.

Business Acquisition [Line Items]

Share price (in Dollars per share) | $ / shares

$ 11.02

Forecast | Standard Bancshares, Inc.

Business Acquisition [Line Items]

Estimated acquisition and integration related expenses

$ 27,000

Acquisitions - Acquisition Acti

Acquisitions - Acquisition Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 06, 2017	Mar. 08, 2016	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Assets
Goodwill			$ 691,481	$ 691,527	$ 340,879	$ 340,757	$ 341,513	$ 319,007
Liabilities
Intangible liabilities			$ 7,208
Standard Bancshares, Inc.
Assets
Cash and due from banks and interest-bearing deposits in other banks	$ 102,149
Securities available-for-sale	214,107
Securities held-to-maturity	0
FHLB and FRB stock	3,247
Loans	1,769,655
OREO	8,424
Investment in BOLI	55,629
Goodwill	339,207
Other intangible assets	31,072
Premises, furniture, and equipment	60,286
Accrued interest receivable and other assets	56,003
Total assets	2,639,779
Liabilities
Noninterest-bearing deposits	675,354
Interest-bearing deposits	1,348,520
Total deposits	2,023,874
Borrowed funds	0
Intangible liabilities	0
Accrued interest payable and other liabilities	35,190
Total liabilities	2,059,064
Consideration Paid
Common stock (2017 - 21,057,085 shares issued at $25.34 per share, 2016 - 3,042,494 shares issued at $18.059 per share), net of issuance costs	533,590
Cash paid	47,125
Total consideration paid	$ 580,715
Common stock, shares issued (in Shares)	21,057,085
Common Stock, shares issued (in dollars per share)	$ 25.34
NI Bancshares Corporation
Assets
Cash and due from banks and interest-bearing deposits in other banks		$ 72,533
Securities available-for-sale		125,843
Securities held-to-maturity		1,864
FHLB and FRB stock		1,549
Loans		396,181
OREO		2,863
Investment in BOLI		8,384
Goodwill		22,174
Other intangible assets		10,408
Premises, furniture, and equipment		19,636
Accrued interest receivable and other assets		16,453
Total assets		677,888
Liabilities
Noninterest-bearing deposits		130,909
Interest-bearing deposits		464,012
Total deposits		594,921
Borrowed funds		2,416
Intangible liabilities		230
Accrued interest payable and other liabilities		10,239
Total liabilities		607,806
Consideration Paid
Common stock (2017 - 21,057,085 shares issued at $25.34 per share, 2016 - 3,042,494 shares issued at $18.059 per share), net of issuance costs		54,896
Cash paid		15,186
Total consideration paid		$ 70,082
Common stock, shares issued (in Shares)		3,042,494
Common Stock, shares issued (in dollars per share)		$ 18.059

Acquisitions - Unaudited Pro Fo

Acquisitions - Unaudited Pro Forma Combined Results of Operations (Details) - Standard Bancshares, Inc. - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Total revenues	[1]	$ 163,241	$ 164,786	$ 482,526	$ 462,962
Net income		$ 38,462	$ 32,589	$ 106,848	$ 85,054
[1]	Includes net interest income and total noninterest income.

Acquisitions - Standard Acquire

Acquisitions - Standard Acquired Loans (Details) - Standard Bancshares, Inc. - Acquired loans $ in Thousands	Jan. 06, 2017USD ($)
Business Acquisition [Line Items]
Fair value	$ 1,643,186
Contractually required principal and interest payments	1,937,060
Best estimate of contractual cash flows not expected to be collected	100,762	[1]
Best estimate of contractual cash flows expected to be collected	1,836,298
PCI
Business Acquisition [Line Items]
Fair value	126,469
Contractually required principal and interest payments	211,931
Best estimate of contractual cash flows not expected to be collected	57,783	[1]
Best estimate of contractual cash flows expected to be collected	$ 154,148
[1]	Includes interest payments not expected to be collected due to loan prepayments as well as principal and interest payments not expected to be collected due to customer default.

Securities - Securities Portfol

Securities - Securities Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 20,425	$ 17,920
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,763,521	1,957,584
Gross Unrealized Gains	2,837	4,562
Gross Unrealized Losses	(33,374)	(42,696)
Fair Value	1,732,984	1,919,450
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,638	22,291
Fair Value	12,921
U.S. treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	42,567	48,581
Gross Unrealized Gains	14	26
Gross Unrealized Losses	(77)	(66)
Fair Value	42,504	48,541
U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	154,666	183,528
Gross Unrealized Gains	303	519
Gross Unrealized Losses	(362)	(410)
Fair Value	154,607	183,637
Collateralized mortgage obligations (CMOs)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	949,762	1,064,130
Gross Unrealized Gains	459	969
Gross Unrealized Losses	(12,999)	(17,653)
Fair Value	937,222	1,047,446
Other mortgage-backed securities (MBSs)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	358,746	337,139
Gross Unrealized Gains	307	1,395
Gross Unrealized Losses	(3,580)	(5,879)
Fair Value	355,473	332,655
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	204,571	273,319
Gross Unrealized Gains	1,294	1,245
Gross Unrealized Losses	(841)	(3,718)
Fair Value	205,024	270,846
Trust-preferred collateralized debt obligations (CDOs)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	45,851	47,681
Gross Unrealized Gains	275	261
Gross Unrealized Losses	(15,300)	(14,682)
Fair Value	30,826	33,260
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,358	3,206
Gross Unrealized Gains	185	147
Gross Unrealized Losses	(215)	(288)
Fair Value	7,328	3,065
Trading Securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	20,425	17,920
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,638	22,291
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,717)	(4,079)
Fair Value	$ 12,921	$ 18,212

Securities - Remaining Contract

Securities - Remaining Contractual Maturity of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale Securities, Amortized Cost [Abstract]
One year or less	$ 97,905
After one year to five years	303,899
After five years to ten years	0
After ten years	45,851
Securities that do not have a single contractual maturity date	1,315,866
Amortized Cost	1,763,521	$ 1,957,584
Available-for-sale Securities, Fair Value [Abstract]
One year or less	94,691
After one year to five years	293,924
After five years to ten years	0
After ten years	44,346
Securities that do not have a single contractual maturity date	1,300,023
Fair Value	1,732,984	1,919,450
Held-to-maturity Securities, Amortized Cost [Abstract]
One year or less	1,947
After one year to five years	6,065
After five years to ten years	2,243
After ten years	4,383
Securities that do not have a single contractual maturity date	0
Amortized Cost	14,638	$ 22,291
Held-to-maturity Securities, Fair Value [Abstract]
One year or less	1,718
After one year to five years	5,354
After five years to ten years	1,980
After ten years	3,869
Securities that do not have a single contractual maturity date	0
Fair Value	$ 12,921

Securities - Additional Informa

Securities - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities pledged as collateral		$ 1,300,000,000	$ 1,100,000,000
Held-to-maturity securities pledged as collateral		0	0
Carrying value of securities sold	$ 210,200,000
OTTI balance		$ 23,300,000	$ 23,300,000

Securities - Securities Gains (

Securities - Securities Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gains on sales of securities:
Gross realized gains	$ 3,197	$ 187	$ 3,481	$ 1,266
Gross realized losses	0	0	0	(169)
Net realized gains on sales of securities	3,197	187	3,481	1,097
Non-cash impairment charges:
Other-than-temporary securities impairment (OTTI)	0	0	0	0
Net realized gains	$ 3,197	$ 187	$ 3,481	$ 1,097

Securities - Securities In An U

Securities - Securities In An Unrealized Loss Position (Details) $ in Thousands	Sep. 30, 2017USD ($)security	Dec. 31, 2016USD ($)security
Securities Available-for-Sale
Number of Securities | security	463	695
Fair Value
Less Than 12 Months	$ 1,014,683	$ 974,337
12 Months or Longer	352,056	567,538
Total	1,366,739	1,541,875
Unrealized Losses
Less Than 12 Months	11,334	18,720
12 Months or Longer	22,040	23,976
Total	$ 33,374	$ 42,696
U.S. treasury securities
Securities Available-for-Sale
Number of Securities | security	16	16
Fair Value
Less Than 12 Months	$ 30,469	$ 33,505
12 Months or Longer	5,998	3,995
Total	36,467	37,500
Unrealized Losses
Less Than 12 Months	51	61
12 Months or Longer	26	5
Total	$ 77	$ 66
U.S. agency securities
Securities Available-for-Sale
Number of Securities | security	33	28
Fair Value
Less Than 12 Months	$ 71,538	$ 62,064
12 Months or Longer	8,241	11,814
Total	79,779	73,878
Unrealized Losses
Less Than 12 Months	291	364
12 Months or Longer	71	46
Total	$ 362	$ 410
CMOs
Securities Available-for-Sale
Number of Securities | security	195	194
Fair Value
Less Than 12 Months	$ 607,645	$ 523,233
12 Months or Longer	241,930	411,758
Total	849,575	934,991
Unrealized Losses
Less Than 12 Months	7,680	10,309
12 Months or Longer	5,319	7,344
Total	$ 12,999	$ 17,653
MBSs
Securities Available-for-Sale
Number of Securities | security	72	68
Fair Value
Less Than 12 Months	$ 262,080	$ 221,174
12 Months or Longer	41,994	77,780
Total	304,074	298,954
Unrealized Losses
Less Than 12 Months	2,851	4,726
12 Months or Longer	729	1,154
Total	$ 3,580	$ 5,880
Municipal securities
Securities Available-for-Sale
Number of Securities | security	138	380
Fair Value
Less Than 12 Months	$ 42,951	$ 133,957
12 Months or Longer	17,045	29,280
Total	59,996	163,237
Unrealized Losses
Less Than 12 Months	461	3,059
12 Months or Longer	380	659
Total	$ 841	$ 3,718
CDOs
Securities Available-for-Sale
Number of Securities | security	7	7
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	30,015	30,592
Total	30,015	30,592
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	15,300	14,682
Total	$ 15,300	$ 14,682
Equity securities
Securities Available-for-Sale
Number of Securities | security	2	2
Fair Value
Less Than 12 Months	$ 0	$ 404
12 Months or Longer	6,833	2,319
Total	6,833	2,723
Unrealized Losses
Less Than 12 Months	0	201
12 Months or Longer	215	86
Total	$ 215	$ 287
Municipal securities
Securities Held-to-Maturity
Number of Securities | security	10	14
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	12,921	18,212
Total	12,921	18,212
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	1,717	4,079
Total	$ 1,717	$ 4,079

Loans - Loan Portfolio (Details

Loans - Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 10,390,292	$ 8,254,145
Deferred loan fees included in total loans	5,189	3,838
Overdrawn demand deposits included in total loans	6,616	7,836
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,900,333	3,217,154
Commercial and industrial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,462,612	2,827,658
Total loans	3,462,612	2,827,658
Commercial and industrial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	437,721	389,496
Total loans	437,721	389,496
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,608,375	3,627,087
Total loans	4,608,375	3,627,087
Commercial real estate | Office, retail, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,960,367	1,581,967
Total loans	1,960,367	1,581,967
Commercial real estate | Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	711,101	614,052
Total loans	711,101	614,052
Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	545,666	451,540
Total loans	545,666	451,540
Commercial real estate | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,391,241	979,528
Total loans	1,391,241	979,528
Total corporate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,508,708	6,844,241
Total loans	8,508,708	6,844,241
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,881,584	1,409,904
Total loans	1,881,584	1,409,904
Consumer loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	847,209	747,983
Total loans	847,209	747,983
Consumer loans | 1-4 family mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	711,607	423,922
Total loans	711,607	423,922
Consumer loans | Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	322,768	237,999
Total loans	$ 322,768	$ 237,999

Loans - Loans Sales (Details)

Loans - Loans Sales (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total net gains on loan sales		$ 2,061	$ 3,307	$ 5,354	$ 6,272
Corporate loan sales
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sales		11,833	12,223	46,770	36,082
Less book value of loans sold		11,512	11,828	45,752	34,718
Total net gains on loan sales	[1]	321	395	1,018	1,364
1-4 family mortgage loan sales
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sales		73,889	110,167	190,544	202,932
Less book value of loans sold		72,149	107,255	186,208	198,024
Total net gains on loan sales	[2]	$ 1,740	$ 2,912	$ 4,336	$ 4,908
[1]	Net gains on corporate loan sales are included in other service charges, commissions, and fees in the Condensed Consolidated Statements of Income.
[2]	Net gains on 1-4 family mortgage loan sales are included in mortgage banking income in the Condensed Consolidated Statements of Income.

Acquired and Covered Loans - Ac

Acquired and Covered Loans - Acquired Loans (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Acquired Loans (Details) - Acquired Loans [Line Items]
Non-PCI	[1]	$ 1,706,506	$ 628,718
Total	[1]	1,863,782	690,385
Acquired loans
Acquired Loans (Details) - Acquired Loans [Line Items]
Non-PCI	[1]	1,694,032	613,339
Total	[1]	1,844,437	667,111
Covered loans
Acquired Loans (Details) - Acquired Loans [Line Items]
Non-PCI	[1]	12,474	15,379
Total	[1]	19,345	23,274
Receivables acquired with deteriorated credit quality
Acquired Loans (Details) - Acquired Loans [Line Items]
PCI	[1]	157,276	61,667
Receivables acquired with deteriorated credit quality | Acquired loans
Acquired Loans (Details) - Acquired Loans [Line Items]
PCI	[1]	150,405	53,772
Receivables acquired with deteriorated credit quality | Covered loans
Acquired Loans (Details) - Acquired Loans [Line Items]
PCI	[1]	$ 6,871	$ 7,895
[1]	Included in loans in the Consolidated Statements of Condition.

Acquired and Covered Loans - Ad

Acquired and Covered Loans - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Acquired Loans [Abstract]
Outstanding balance of PCI loans	$ 229,100		$ 229,100		$ 84,800
Renewed non-purchased credit impaired loans	304,000		304,000		$ 117,600
Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items]
Accretion on acquired loans	4,263	$ 2,763	12,106	$ 6,612
Acquired and Covered Receivables
Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items]
Accretion on acquired loans	$ 7,600	$ 4,600	$ 27,700	$ 11,900

Acquired and Covered Loans - Ch

Acquired and Covered Loans - Changes in FDIC Indemnification Asset (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
FDIC Indemnification Asset [Roll Forward]
Beginning balance	$ 3,918	$ 5,171	$ 4,522	$ 3,903
Amortization	(302)	(302)	(906)	(884)
Change in expected reimbursements from the FDIC for changes in expected credit losses	(123)	(228)	(653)	(487)
Net payments to the FDIC	123	191	653	2,300
Ending balance	$ 3,616	$ 4,832	$ 3,616	$ 4,832

Acquired and Covered Loans - 54

Acquired and Covered Loans - Changes in Accretable Yield (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Changes in Accretable Yield [Roll Forward]
Beginning balances		$ 39,870	$ 25,082	$ 19,385	$ 24,912
Additions		0	0	27,316	3,981
Accretion		(4,263)	(2,763)	(12,106)	(6,612)
Other	[1]	478	(1,012)	1,490	(974)
Ending balance		$ 36,085	$ 21,307	$ 36,085	$ 21,307
[1]	Increases represent a rise in the expected future cash flows to be collected over the remaining estimated life of the underlying portfolio while decreases result from the resolution of certain loans occurring earlier than anticipated.

Past Due Loans, Allowance For55

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		Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	$ 10,340,480	$ 8,204,440
Total Past Due		49,812	49,705
Total Loans		10,390,292	8,254,145
Non- accrual	[2]	65,176	59,289
90 Days or More Past Due, Still Accruing Interest		2,839	5,009
Receivables acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI	[3]	157,276	61,667
Receivables acquired with deteriorated credit quality | Non-accrual
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI		239	681
30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		33,229	22,923
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		16,583	26,782
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans		3,900,333	3,217,154
Commercial and industrial | Receivables acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI		25,217	3,182
Commercial and industrial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	3,444,056	2,816,442
Total Past Due		18,556	11,216
Total Loans		3,462,612	2,827,658
Non- accrual	[2]	41,504	29,938
90 Days or More Past Due, Still Accruing Interest		1,166	374
Commercial and industrial | Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	436,693	388,596
Total Past Due		1,028	900
Total Loans		437,721	389,496
Non- accrual	[2]	380	181
90 Days or More Past Due, Still Accruing Interest		335	736
Commercial and industrial | 30-89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		14,536	6,426
Commercial and industrial | 30-89 Days Past Due | Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		325	0
Commercial and industrial | 90 Days or More Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4,020	4,790
Commercial and industrial | 90 Days or More Past Due | Agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		703	900
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	4,591,057	3,601,955
Total Past Due		17,318	25,132
Total Loans		4,608,375	3,627,087
Non- accrual	[2]	14,759	20,766
90 Days or More Past Due, Still Accruing Interest		852	3,259
Commercial real estate | Receivables acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI		109,995	41,461
Commercial real estate | Office, retail, and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	1,950,010	1,564,007
Total Past Due		10,357	17,960
Total Loans		1,960,367	1,581,967
Non- accrual	[2]	12,221	17,277
90 Days or More Past Due, Still Accruing Interest		0	1,129
Commercial real estate | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	707,959	612,446
Total Past Due		3,142	1,606
Total Loans		711,101	614,052
Non- accrual	[2]	153	311
90 Days or More Past Due, Still Accruing Interest		129	604
Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	545,119	450,927
Total Past Due		547	613
Total Loans		545,666	451,540
Non- accrual	[2]	146	286
90 Days or More Past Due, Still Accruing Interest		374	0
Commercial real estate | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	1,387,969	974,575
Total Past Due		3,272	4,953
Total Loans		1,391,241	979,528
Non- accrual	[2]	2,239	2,892
90 Days or More Past Due, Still Accruing Interest		349	1,526
Commercial real estate | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		8,809	7,824
Commercial real estate | 30-89 Days Past Due | Office, retail, and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4,411	5,327
Commercial real estate | 30-89 Days Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		3,013	858
Commercial real estate | 30-89 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		29	332
Commercial real estate | 30-89 Days Past Due | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,356	1,307
Commercial real estate | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		8,509	17,308
Commercial real estate | 90 Days or More Past Due | Office, retail, and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		5,946	12,633
Commercial real estate | 90 Days or More Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		129	748
Commercial real estate | 90 Days or More Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		518	281
Commercial real estate | 90 Days or More Past Due | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,916	3,646
Total corporate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	8,471,806	6,806,993
Total Past Due		36,902	37,248
Total Loans		8,508,708	6,844,241
Non- accrual	[2]	56,643	50,885
90 Days or More Past Due, Still Accruing Interest		2,353	4,369
Total corporate loans | Receivables acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI		135,212	44,643
Total corporate loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		23,670	14,250
Total corporate loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		13,232	22,998
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	1,868,674	1,397,447
Total Past Due		12,910	12,457
Total Loans		1,881,584	1,409,904
Non- accrual	[2]	8,533	8,404
90 Days or More Past Due, Still Accruing Interest		486	640
Consumer loans | Receivables acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI		22,064	17,024
Consumer loans | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	840,966	740,919
Total Past Due		6,243	7,064
Total Loans		847,209	747,983
Non- accrual	[2]	5,529	5,465
90 Days or More Past Due, Still Accruing Interest		44	109
Consumer loans | 1-4 family mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	707,498	420,264
Total Past Due		4,109	3,658
Total Loans		711,607	423,922
Non- accrual	[2]	3,004	2,939
90 Days or More Past Due, Still Accruing Interest		0	272
Consumer loans | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	[1]	320,210	236,264
Total Past Due		2,558	1,735
Total Loans		322,768	237,999
Non- accrual	[2]	0	0
90 Days or More Past Due, Still Accruing Interest		442	259
Consumer loans | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		9,559	8,673
Consumer loans | 30-89 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		3,729	4,545
Consumer loans | 30-89 Days Past Due | 1-4 family mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		3,714	2,652
Consumer loans | 30-89 Days Past Due | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		2,116	1,476
Consumer loans | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		3,351	3,784
Consumer loans | 90 Days or More Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		2,514	2,519
Consumer loans | 90 Days or More Past Due | 1-4 family mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		395	1,006
Consumer loans | 90 Days or More Past Due | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		$ 442	$ 259
[1]	PCI loans with an accretable yield are considered current.
[2]	Includes PCI loans of $239,000 and $681,000 as of September 30, 2017 and December 31, 2016, respectively, which no longer have an accretable yield as estimates of expected future cash flows have decreased since the acquisition due to credit deterioration.
[3]	Included in loans in the Consolidated Statements of Condition.

Past Due Loans, Allowance For56

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	$ 93,371	$ 81,505	$ 87,083	$ 74,855
Charge-offs	(10,566)	(5,950)	(21,703)	(17,272)
Recoveries	2,900	1,155	7,168	3,274
Net charge-offs	(7,666)	(4,795)	(14,535)	(13,998)
Provision for loan losses and other	10,109	9,598	23,266	25,451
Ending balance	95,814	86,308	95,814	86,308
Reserve for Unfunded Commitments
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	1,000	1,400	1,000	1,225
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net charge-offs	0	0	0	0
Provision for loan losses and other	0	(400)	0	(225)
Ending balance	1,000	1,000	1,000	1,000
Commercial, Industrial, and Agricultural
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	46,271	40,084	40,709	37,074
Charge-offs	(8,935)	(1,760)	(15,966)	(5,684)
Recoveries	698	615	2,764	1,693
Net charge-offs	(8,237)	(1,145)	(13,202)	(3,991)
Provision for loan losses and other	13,994	3,579	24,521	9,435
Ending balance	52,028	42,518	52,028	42,518
Commercial Real Estate
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance			32,039
Ending balance	25,836		25,836
Commercial Real Estate | Office, Retail, and Industrial
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	15,008	12,985	17,595	13,124
Charge-offs	(14)	(2,193)	(141)	(4,358)
Recoveries	1,825	42	2,808	153
Net charge-offs	1,811	(2,151)	2,667	(4,205)
Provision for loan losses and other	(5,129)	3,019	(8,572)	4,934
Ending balance	11,690	13,853	11,690	13,853
Commercial Real Estate | Multi-family
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	2,919	2,933	3,261	2,469
Charge-offs	0	0	0	(288)
Recoveries	2	69	36	95
Net charge-offs	2	69	36	(193)
Provision for loan losses and other	(296)	1,048	(672)	1,774
Ending balance	2,625	4,050	2,625	4,050
Commercial Real Estate | Construction
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	4,094	2,239	3,444	1,440
Charge-offs	6	0	(38)	(134)
Recoveries	19	9	258	44
Net charge-offs	25	9	220	(90)
Provision for loan losses and other	161	916	616	1,814
Ending balance	4,280	3,164	4,280	3,164
Commercial Real Estate | Other Commercial Real Estate
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	7,479	7,492	7,739	6,109
Charge-offs	(6)	(509)	(721)	(2,833)
Recoveries	25	94	205	314
Net charge-offs	19	(415)	(516)	(2,519)
Provision for loan losses and other	(257)	1,490	18	4,977
Ending balance	7,241	8,567	7,241	8,567
Consumer
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance			13,335
Ending balance	16,950		16,950
Consumer | Consumer
Allowance for Credit Losses by Portfolio Segment [Roll Forward]
Beginning balance	16,600	14,372	13,335	13,414
Charge-offs	(1,617)	(1,488)	(4,837)	(3,975)
Recoveries	331	326	1,097	975
Net charge-offs	(1,286)	(1,162)	(3,740)	(3,000)
Provision for loan losses and other	1,636	(54)	7,355	2,742
Ending balance	$ 16,950	$ 13,156	$ 16,950	$ 13,156

Past Due Loans, Allowance For57

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		Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		$ 51,383		$ 42,650
Loans Collectively Evaluated for Impairment		10,181,633		8,149,828
Loans		10,390,292		8,254,145
Allowance for Credit Losses Individually Evaluated for Impairment		3,417		525
Allowance for Credit Losses Collectively Evaluated for Impairment		87,792		81,864
Total Allowance for Credit Losses		95,814	$ 93,371	87,083	$ 86,308	$ 81,505	$ 74,855
PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI	[1]	157,276		61,667
Total Allowance for Credit Losses		4,605		4,694
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
Loans		0		0
Allowance for Credit Losses Individually Evaluated for Impairment		0		0
Allowance for Credit Losses Collectively Evaluated for Impairment		1,000		1,000
Total Allowance for Credit Losses		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 and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		39,121		24,645
Loans Collectively Evaluated for Impairment		3,835,995		3,189,327
Loans		3,900,333		3,217,154
Allowance for Credit Losses Individually Evaluated for Impairment		3,408		507
Allowance for Credit Losses Collectively Evaluated for Impairment		48,107		39,554
Total Allowance for Credit Losses		52,028	$ 46,271	40,709	$ 42,518	$ 40,084	$ 37,074
Commercial and industrial | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		25,217		3,182
Total Allowance for Credit Losses		513		648
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		12,262		18,005
Loans Collectively Evaluated for Impairment		4,486,118		3,567,621
Loans		4,608,375		3,627,087
Allowance for Credit Losses Individually Evaluated for Impairment		9		18
Allowance for Credit Losses Collectively Evaluated for Impairment		23,001		29,100
Total Allowance for Credit Losses		25,836		32,039
Commercial real estate | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		109,995		41,461
Total Allowance for Credit Losses		2,826		2,921
Commercial real estate | Office, retail, and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		11,211		16,287
Loans Collectively Evaluated for Impairment		1,932,332		1,553,234
Loans		1,960,367		1,581,967
Allowance for Credit Losses Individually Evaluated for Impairment		9		0
Allowance for Credit Losses Collectively Evaluated for Impairment		10,291		16,148
Total Allowance for Credit Losses		11,690		17,595
Commercial real estate | Office, retail, and industrial | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		16,824		12,446
Total Allowance for Credit Losses		1,390		1,447
Commercial real estate | Multi-family
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		395		398
Loans Collectively Evaluated for Impairment		696,490		601,429
Loans		711,101		614,052
Allowance for Credit Losses Individually Evaluated for Impairment		0		0
Allowance for Credit Losses Collectively Evaluated for Impairment		2,524		3,059
Total Allowance for Credit Losses		2,625		3,261
Commercial real estate | Multi-family | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		14,216		12,225
Total Allowance for Credit Losses		101		202
Commercial real estate | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		0		34
Loans Collectively Evaluated for Impairment		532,016		447,058
Loans		545,666		451,540
Allowance for Credit Losses Individually Evaluated for Impairment		0		0
Allowance for Credit Losses Collectively Evaluated for Impairment		4,060		3,280
Total Allowance for Credit Losses		4,280		3,444
Commercial real estate | Construction | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		13,650		4,448
Total Allowance for Credit Losses		220		164
Commercial real estate | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		656		1,286
Loans Collectively Evaluated for Impairment		1,325,280		965,900
Loans		1,391,241		979,528
Allowance for Credit Losses Individually Evaluated for Impairment		0		18
Allowance for Credit Losses Collectively Evaluated for Impairment		6,126		6,613
Total Allowance for Credit Losses		7,241		7,739
Commercial real estate | Other commercial real estate | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		65,305		12,342
Total Allowance for Credit Losses		1,115		1,108
Total corporate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		51,383		42,650
Loans Collectively Evaluated for Impairment		8,322,113		6,756,948
Loans		8,508,708		6,844,241
Allowance for Credit Losses Individually Evaluated for Impairment		3,417		525
Allowance for Credit Losses Collectively Evaluated for Impairment		71,108		68,654
Total Allowance for Credit Losses		77,864		72,748
Total corporate loans | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		135,212		44,643
Total Allowance for Credit Losses		3,339		3,569
Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Individually Evaluated for Impairment		0		0
Loans Collectively Evaluated for Impairment		1,859,520		1,392,880
Loans		1,881,584		1,409,904
Allowance for Credit Losses Individually Evaluated for Impairment		0		0
Allowance for Credit Losses Collectively Evaluated for Impairment		15,684		12,210
Total Allowance for Credit Losses		16,950		13,335
Consumer loans | PCI
Financing Receivable, Allowance for Credit Losses [Line Items]
PCI		22,064		17,024
Total Allowance for Credit Losses		$ 1,266		$ 1,125
[1]	Included in loans in the Consolidated Statements of Condition.

Past Due Loans, Allowance For58

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - Impaired Loans Individually Evaluated by Class (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	$ 32,885	$ 29,314
Recorded Investment in Loans with a Specific Reserve	18,498	13,336
Unpaid Principal Balance	63,329	53,144
Specific Reserve	3,417	525
Commercial and industrial | Commercial and industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	24,688	11,579
Recorded Investment in Loans with a Specific Reserve	14,433	13,066
Unpaid Principal Balance	47,700	29,514
Specific Reserve	3,408	507
Commercial and industrial | Agricultural
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	0	0
Recorded Investment in Loans with a Specific Reserve	0	0
Unpaid Principal Balance	0	0
Specific Reserve	0	0
Commercial real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	8,197	17,735
Recorded Investment in Loans with a Specific Reserve	4,065	270
Unpaid Principal Balance	15,629	23,630
Specific Reserve	9	18
Commercial real estate | Office, retail, and industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	7,146	16,287
Recorded Investment in Loans with a Specific Reserve	4,065	0
Unpaid Principal Balance	14,480	21,057
Specific Reserve	9	0
Commercial real estate | Multi-family
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	395	398
Recorded Investment in Loans with a Specific Reserve	0	0
Unpaid Principal Balance	395	398
Specific Reserve	0	0
Commercial real estate | Construction
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	0	34
Recorded Investment in Loans with a Specific Reserve	0	0
Unpaid Principal Balance	0	34
Specific Reserve	0	0
Commercial real estate | Other commercial real estate
Financing Receivable, Impaired [Line Items]
Recorded Investment in Loans with No Specific Reserve	656	1,016
Recorded Investment in Loans with a Specific Reserve	0	270
Unpaid Principal Balance	754	2,141
Specific Reserve	$ 0	$ 18

Past Due Loans, Allowance For59

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - Impaired Loans Individually Evaluated by Class (Continued) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		$ 59,129	$ 26,924	$ 48,850	$ 21,084
Interest Income Recognized	[1]	368	71	1,370	271
Commercial and industrial | Commercial and industrial
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		44,682	7,829	32,765	5,312
Interest Income Recognized	[1]	368	57	924	107
Commercial and industrial | Agricultural
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		140	0	348	0
Interest Income Recognized	[1]	0	0	0	0
Commercial real estate
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		14,307	19,095	15,737	15,772
Interest Income Recognized	[1]	0	14	446	164
Commercial real estate | Office, retail, and industrial
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		12,496	16,101	13,680	12,012
Interest Income Recognized	[1]	0	3	262	80
Commercial real estate | Multi-family
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		396	399	396	500
Interest Income Recognized	[1]	0	11	28	12
Commercial real estate | Construction
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		0	34	9	70
Interest Income Recognized	[1]	0	0	136	0
Commercial real estate | Other commercial real estate
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		1,415	2,561	1,652	3,190
Interest Income Recognized	[1]	$ 0	$ 0	$ 20	$ 72
[1]	Recorded using the cash basis of accounting.

Past Due Loans, Allowance For60

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - Credit Quality Indicators by Class (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Accruing		$ 1,813	$ 2,291
Special Mention and Substandard Loans
Financing Receivable, Recorded Investment [Line Items]
Accruing		664	834
Total corporate loans
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		8,508,708	6,844,241
Total corporate loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		8,144,005	6,493,957
Total corporate loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	158,959	159,675
Total corporate loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	149,101	139,724
Total corporate loans | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	56,643	50,885
Commercial and industrial | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		3,462,612	2,827,658
Accruing		269	281
Commercial and industrial | Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		3,286,087	2,638,833
Commercial and industrial | Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	72,491	92,340
Commercial and industrial | Commercial and industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	62,530	66,547
Commercial and industrial | Commercial and industrial | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	41,504	29,938
Commercial and industrial | Agricultural
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		437,721	389,496
Accruing		0	0
Commercial and industrial | Agricultural | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		417,612	366,382
Commercial and industrial | Agricultural | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	13,310	17,039
Commercial and industrial | Agricultural | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	6,419	5,894
Commercial and industrial | Agricultural | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	380	181
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		4,608,375	3,627,087
Accruing		771	1,009
Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		4,440,306	3,488,742
Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	73,158	50,296
Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	80,152	67,283
Commercial real estate | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	14,759	20,766
Commercial real estate | Office, retail, and industrial
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		1,960,367	1,581,967
Accruing		0	155
Commercial real estate | Office, retail, and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		1,877,165	1,491,170
Commercial real estate | Office, retail, and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	25,919	34,007
Commercial real estate | Office, retail, and industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	45,062	39,513
Commercial real estate | Office, retail, and industrial | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	12,221	17,277
Commercial real estate | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		711,101	614,052
Accruing		577	586
Commercial real estate | Multi-family | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		703,659	607,342
Commercial real estate | Multi-family | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	5,433	4,370
Commercial real estate | Multi-family | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	1,856	2,029
Commercial real estate | Multi-family | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	153	311
Commercial real estate | Construction
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		545,666	451,540
Accruing		0	0
Commercial real estate | Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		525,097	438,946
Commercial real estate | Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	9,113	111
Commercial real estate | Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	11,310	12,197
Commercial real estate | Construction | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	146	286
Commercial real estate | Other commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		1,391,241	979,528
Accruing		194	268
Commercial real estate | Other commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class		1,334,385	951,284
Commercial real estate | Other commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[1],[2]	32,693	11,808
Commercial real estate | Other commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[2],[3]	21,924	13,544
Commercial real estate | Other commercial real estate | Non-accrual
Financing Receivable, Recorded Investment [Line Items]
Credit Quality Indicators by Class	[4]	$ 2,239	$ 2,892
[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]	Total special mention and substandard loans includes accruing TDRs of $664,000 as of September 30, 2017 and $834,000 as of December 31, 2016.
[3]	Loans categorized as substandard exhibit well-defined weaknesses 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.
[4]	Loans categorized as non-accrual exhibit well-defined weaknesses that may jeopardize the liquidation of the debt or result in a loss if the deficiencies are not corrected.

Past Due Loans, Allowance For61

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - Credit Quality Indicators by Class (Continued) (Details) - Consumer loans - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
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	$ 1,881,584	$ 1,409,904
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	1,873,051	1,401,500
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	8,533	8,404
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	847,209	747,983
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	841,680	742,518
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	5,529	5,465
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	711,607	423,922
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	708,603	420,983
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	3,004	2,939
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	322,768	237,999
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	322,768	237,999
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 For62

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - TDRs By Class (Details) - USD ($)		Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		$ 1,813,000	$ 2,291,000
Non-accrual	[1]	28,662,000	6,297,000
Total		30,475,000	8,588,000	$ 3,958,000
Specific reserves related to TDRs		1,300,000	0
Material commitments to lend additional funds to borrowers with TDRs		0	0
Commercial and industrial | Commercial and industrial
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		269,000	281,000
Non-accrual	[1]	22,780,000	150,000
Total		23,049,000	431,000
Commercial and industrial | Agricultural
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		0	0
Non-accrual	[1]	0	0
Total		0	0
Commercial real estate
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		771,000	1,009,000
Non-accrual	[1]	4,665,000	4,949,000
Total		5,436,000	5,958,000
Commercial real estate | Office, retail, and industrial
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		0	155,000
Non-accrual	[1]	4,512,000	4,733,000
Total		4,512,000	4,888,000
Commercial real estate | Multi-family
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		577,000	586,000
Non-accrual	[1]	153,000	168,000
Total		730,000	754,000
Commercial real estate | Construction
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		0	0
Non-accrual	[1]	0	0
Total		0	0
Commercial real estate | Other commercial real estate
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		194,000	268,000
Non-accrual	[1]	0	48,000
Total		194,000	316,000
Total corporate loans
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		1,040,000	1,290,000
Non-accrual	[1]	27,445,000	5,099,000
Total		28,485,000	6,389,000
Consumer loans
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		773,000	1,001,000
Non-accrual	[1]	1,217,000	1,198,000
Total		1,990,000	2,199,000
Consumer loans | Home equity
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		88,000	177,000
Non-accrual	[1]	755,000	820,000
Total		843,000	997,000
Consumer loans | 1-4 family mortgages
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		685,000	824,000
Non-accrual	[1]	462,000	378,000
Total		1,147,000	1,202,000
Consumer loans | Installment
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing		0	0
Non-accrual	[1]	0	0
Total		$ 0	$ 0
[1]	These TDRs are included in non-accrual loans in the preceding tables.

Past Due Loans, Allowance For63

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - TDRs That Were Restructured (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017USD ($)loan	Sep. 30, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	12	14
Pre- Modification Recorded Investment	$ 29,467	$ 30,389
Funds Disbursed	196	196
Interest and Escrow Capitalized	0	0
Charge-offs	1,736	1,736
Post- Modification Recorded Investment	$ 27,927	$ 28,849
Commercial and industrial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	10	12
Pre- Modification Recorded Investment	$ 25,811	$ 26,733
Funds Disbursed	196	196
Interest and Escrow Capitalized	0	0
Charge-offs	1,736	1,736
Post- Modification Recorded Investment	$ 24,271	$ 25,193
Commercial real estate | Office, retail, and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	2	2
Pre- Modification Recorded Investment	$ 3,656	$ 3,656
Funds Disbursed	0	0
Interest and Escrow Capitalized	0	0
Charge-offs	0	0
Post- Modification Recorded Investment	$ 3,656	$ 3,656

Past Due Loans, Allowance For64

Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - TDR Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Troubled Debt Restructuring Activity Rollforward [Roll Forward]
Beginning balance			$ 8,588
Additions	$ 27,927		28,849
Ending balance	30,475	$ 3,958	30,475	$ 3,958
Accruing
Troubled Debt Restructuring Activity Rollforward [Roll Forward]
Beginning balance	2,029	2,491	2,291	2,743
Additions	14,897	0	15,819	0
Net payments received	(1,798)	(22)	(1,905)	(91)
Net transfers to non-accrual	(13,315)	(101)	(14,392)	(284)
Ending balance	1,813	2,368	1,813	2,368
Non-accrual
Troubled Debt Restructuring Activity Rollforward [Roll Forward]
Beginning balance	3,036	1,690	6,297	2,324
Additions	14,570	0	14,570	0
Net payments received	(127)	(31)	(4,352)	(609)
Charge-offs	(2,132)	(170)	(2,245)	(409)
Net transfers from accruing	13,315	101	14,392	284
Ending balance	$ 28,662	$ 1,590	$ 28,662	$ 1,590

Premises, Furniture, and Equi65

Premises, Furniture, and Equipment - Schedule of Premises, Furniture, and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Land	$ 30,267	$ 18,304
Premises	119,325	94,369
Furniture and equipment	114,547	105,859
Total cost	264,139	218,532
Accumulated depreciation	(142,001)	(140,030)
Net book value of premises, furniture, and equipment	122,138	78,502
Assets held-for-sale	9,157	4,075
Total premises, furniture, and equipment	$ 131,295	$ 82,577

Premises, Furniture, and Equi66

Premises, Furniture, and Equipment - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)retail_branchrenewal_option
Property, Plant and Equipment [Line Items]
Aggregate cash purchase price					$ 150.3
Number of branches sold | retail_branch					55
Net book value of properties					$ 58.8
Initial term of lease for sale-leaseback transaction					14 years
Number of lease renewal options | renewal_option					5
Pre-tax gain on sale-leaseback transaction					$ 88
Deferred gain, net	$ 76.1		$ 76.1		$ 82.5
Depreciation of premises, furniture, and equipment	$ 3.5	$ 3.4	$ 10.5	$ 10.1
Five Year Renewal Period
Property, Plant and Equipment [Line Items]
Renewal lease periods for sale-leaseback transactions					5 years

Premises, Furniture, and Equi67

Premises, Furniture, and Equipment - Operating Leases (Details) $ in Thousands	Sep. 30, 2017USD ($)
Property, Plant and Equipment [Abstract]
One year or less	$ 19,298
After one year to two years	17,737
After two years to three years	17,008
After three years to four years	16,815
After four years to five years	16,550
After five years	120,048
Total minimum lease payments	$ 207,456

Premises, Furniture, and Equi68

Premises, Furniture, and Equipment - Accretion of Operating Leases (Details) $ in Thousands	Sep. 30, 2017USD ($)
Property, Plant and Equipment [Abstract]
One year or less	$ 1,011
After one year to two years	742
After two years to three years	648
After three years to four years	648
After four years to five years	648
After five years	3,511
Total accretion	$ 7,208

Premises, Furniture, and Equi69

Premises, Furniture, and Equipment - Rental Expense (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Lease expense charged to operations		$ 4,747	$ 2,229	$ 14,027	$ 5,729
Accretion of operating lease intangible	[1]	(295)	(295)	(885)	(876)
Accretion of deferred gain on sale-leaseback transaction	[1]	(1,463)	0	(4,409)	0
Rental income from premises leased to others	[1]	(171)	(118)	(521)	(404)
Net operating lease expense		$ 2,818	$ 1,816	$ 8,212	$ 4,449
[1]	Included as reductions to net occupancy and equipment expense in the Condensed Consolidated Statements of Income.

Goodwill and Other Intangible70

Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Goodwill [Roll Forward]
Beginning balance	$ 691,527	$ 341,513	$ 340,879	$ 319,007
Acquisitions	(46)	(756)	350,602	21,750
Ending balance	$ 691,481	$ 340,757	$ 691,481	$ 340,757

Goodwill and Other Intangible71

Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Finite-lived Intangible Assets [Roll Forward]
Balance at the beginning of the year, gross	$ 58,959	$ 48,550
Balance at the beginning of the year, accumulated amortization	32,962	28,280
Balance at the beginning of the year, net	25,997	20,270
Additions	39,017	10,409
Amortization expense	6,059	3,475
Balance at the end of the year, gross	97,976	58,959
Balance at the end of the year, accumulated amortization	39,021	31,755
Balance at the end of the year, net	$ 58,955	$ 27,204

Goodwill and Other Intangible72

Goodwill and Other Intangible Assets - Amortization of Other Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 7,173
2,019	7,083
2,020	7,036
2,021	6,970
2,022	6,898
2023 and thereafter	23,795
Total	$ 58,955	$ 25,997	$ 27,204	$ 20,270

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Deposits [Abstract]
Demand deposits	$ 3,580,922	$ 2,766,748
Savings deposits	2,022,717	1,615,833
NOW accounts	2,048,893	1,675,421
Money market deposits	1,969,865	1,577,316
Time deposits less than $100,000	888,238	755,558
Time deposits greater than $100,000	697,862	437,727
Total deposits	$ 11,208,497	$ 8,828,603

Borrowed Funds - Summary of Bor

Borrowed Funds - Summary of Borrowed Funds (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Securities sold under agreements to repurchase	$ 110,536	$ 129,008
FHLB advances	590,000	750,000
Total borrowed funds	$ 700,536	$ 879,008

Borrowed Funds - Additional Inf

Borrowed Funds - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 27, 2016
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
One-Month LIBOR Plus 1.75%
Short-term Debt [Line Items]
Line of credit interest rate spread	1.75%
FHLB Advances
Short-term Debt [Line Items]
FHLB maturity date range, start	Oct. 2, 2017
FHLB maturity date range, end	Dec. 1, 2017
FHLB Advances | Minimum
Short-term Debt [Line Items]
FHLB fixed interest rate	1.18%
FHLB Advances | Maximum
Short-term Debt [Line Items]
FHLB fixed interest rate	1.24%

Material Transactions Affecti76

Material Transactions Affecting Stockholders' Equity (Details) - $ / shares	May 17, 2017	Sep. 30, 2017	Dec. 31, 2016
Equity [Abstract]
Increase to authorized common stock (in shares)	100,000,000
Increase to common and preferred shares authorized (in shares)	251,000,000
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000	1,000,000
Common stock, shares authorized (in shares)	250,000,000	250,000,000	150,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net income		$ 38,235	$ 28,402	$ 96,040	$ 71,631
Net income applicable to non-vested restricted shares		(340)	(324)	(910)	(826)
Net income applicable to common shares		$ 37,895	$ 28,078	$ 95,130	$ 70,805
Weighted-average common shares outstanding:
Weighted-average common shares outstanding (basic) (in Shares)		101,752	80,396	101,307	79,589
Dilutive effect of common stock equivalents (in Shares)		20	13	20	13
Weighted-average diluted common shares outstanding (in Shares)		101,772	80,409	101,327	79,602
Basic EPS (in dollars per share)		$ 0.37	$ 0.35	$ 0.94	$ 0.89
Diluted EPS (in dollars per share)		$ 0.37	$ 0.35	$ 0.94	$ 0.89
Anti-dilutive shares not included in the computation of diluted EPS (in Shares)	[1]	190	454	242	510
[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.

Derivative Instruments and He78

Derivative Instruments and Hedging Activities - Fair Value Hedges (Details) - Fair Value Hedging - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross notional amount outstanding		$ 5,583	$ 5,958
Derivative liability fair value		$ (146)	$ (282)
Weighted-average interest rate received		3.23%	2.63%
Weighted-average interest rate paid		5.96%	5.96%
Weighted-average maturity (in years)		1 year 1 month 5 days	1 year 10 months 2 days
Fair value of derivative	[1]	$ 157	$ 296
[1]	This amount represents the fair value if credit risk related contingent features were triggered.

Derivative Instruments and He79

Derivative Instruments and Hedging Activities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Feb. 28, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Amount of variable rate loans hedged using interest rate swaps	$ 980,000		$ 980,000
Amount hedged of borrowed funds using forward starting interest rate swaps	980,000		980,000		$ 415,000
Amount to be hedged of borrowed funds using forward starting interest rate swaps	$ 565,000		$ 565,000
Weighted-average interest rate to be paid	1.96%		1.96%
Interest rate cash flow hedge loss to be reclassified during next 12 months, net	$ 581		$ 581
Capital market products income	$ 2,592	$ 2,916	$ 6,185	$ 8,197
Portion of fair value of outstanding interest rate swaps covered by collateral agreements (percent)	100.00%		100.00%			100.00%

Derivative Instruments and He80

Derivative Instruments and Hedging Activities - Cash Flow Hedges (Details) - Cash Flow Hedging - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross notional amount outstanding	$ 1,960,000	$ 1,470,000
Derivative asset fair value	3,234	5,402
Derivative liability fair value	$ (6,729)	$ (7,390)
Weighted-average interest rate received	1.55%	1.37%
Weighted-average interest rate paid	1.51%	1.11%
Weighted-average maturity (in years)	2 years 6 months	2 years 9 months 28 days

Derivative Instruments and He81

Derivative Instruments and Hedging Activities - Other Derivative Instruments (Details) - Other Derivative Instruments - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Gross notional amount outstanding		$ 2,463,967	$ 1,656,612
Derivative asset fair value		18,268	13,478
Derivative liability fair value		(14,443)	(13,478)
Fair value of derivative	[1]	$ 14,704	$ 13,753
[1]	This amount represents the fair value if credit risk related contingent features were triggered.

Derivative Instruments and He82

Derivative Instruments and Hedging Activities - Offsetting Derivatives (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Assets
Gross amounts recognized		$ 21,502	$ 18,880
Less: amounts offset in the Consolidated Statements of Financial Condition		0	0
Net amount presented in the Consolidated Statements of Financial Condition	[1]	21,502	18,880
Offsetting derivative positions		(16,557)	(10,889)
Cash collateral pledged		0	0
Net credit exposure		4,945	7,991
Liabilities
Gross amounts recognized		21,318	21,150
Less: amounts offset in the Consolidated Statements of Financial Condition		0	0
Net amount presented in the Consolidated Statements of Financial Condition	[1]	21,318	21,150
Offsetting derivative positions		(16,557)	(10,889)
Cash collateral pledged		(4,761)	(10,261)
Net credit exposure		$ 0	$ 0
[1]	Included in other assets or other liabilities in the Consolidated Statements of Financial Condition.

Commitments, Guarantees, and 83

Commitments, Guarantees, and Contingent Liabilities (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Other Commitments [Line Items]
Letters of credit		$ 132,990	$ 100,430
Commitments to extend credit
Other Commitments [Line Items]
Commercial, industrial, and agricultural		1,739,259	1,522,152
Commercial real estate		322,705	397,423
Home equity		512,560	426,384
Other commitments	[1]	246,609	214,943
Total commitments to extend credit		$ 2,821,133	$ 2,560,902
[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		Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Trading securities:
Total trading securities		$ 20,425		$ 17,920
Securities Available-for-Sale
Securities available-for-sale, at fair value		1,732,984		1,919,450
Mortgage servicing rights (MSRs)		5,766	$ 5,925	6,120	$ 5,076	$ 4,938	$ 1,853
U.S. treasury securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		42,504		48,541
U.S. agency securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		154,607		183,637
MBSs
Securities Available-for-Sale
Securities available-for-sale, at fair value		355,473		332,655
Municipal securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		205,024		270,846
CDOs
Securities Available-for-Sale
Securities available-for-sale, at fair value		30,826		33,260
Equity securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		7,328		3,065
Recurring | Level 1
Trading securities:
Money market funds		1,738		1,645
Mutual funds		18,687		16,275
Total trading securities		20,425		17,920
Securities Available-for-Sale
Securities available-for-sale, at fair value		42,504		48,541
Mortgage servicing rights (MSRs)	[1]	0		0
Derivative assets	[1]	0		0
Liabilities:
Derivative liabilities	[2]	0		0
Recurring | Level 1 | U.S. treasury securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		42,504		48,541
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 | CDOs
Securities Available-for-Sale
Securities available-for-sale, at fair value		0		0
Recurring | Level 1 | Equity securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		0		0
Recurring | Level 2
Trading securities:
Money market funds		0		0
Mutual funds		0		0
Total trading securities		0		0
Securities Available-for-Sale
Securities available-for-sale, at fair value		1,659,654		1,837,649
Mortgage servicing rights (MSRs)	[1]	0		0
Derivative assets	[1]	21,502		18,880
Liabilities:
Derivative liabilities	[2]	21,318		21,150
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		154,607		183,637
Recurring | Level 2 | CMOs
Securities Available-for-Sale
Securities available-for-sale, at fair value		937,222		1,047,446
Recurring | Level 2 | MBSs
Securities Available-for-Sale
Securities available-for-sale, at fair value		355,473		332,655
Recurring | Level 2 | Municipal securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		205,024		270,846
Recurring | Level 2 | CDOs
Securities Available-for-Sale
Securities available-for-sale, at fair value		0		0
Recurring | Level 2 | Equity securities
Securities Available-for-Sale
Securities available-for-sale, at fair value		7,328		3,065
Recurring | Level 3
Trading securities:
Money market funds		0		0
Mutual funds		0		0
Total trading securities		0		0
Securities Available-for-Sale
Securities available-for-sale, at fair value		30,826		33,260
Mortgage servicing rights (MSRs)	[1]	5,766		6,120
Derivative assets	[1]	0		0
Liabilities:
Derivative liabilities	[2]	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 | CDOs
Securities Available-for-Sale
Securities available-for-sale, at fair value		30,826		33,260
Recurring | Level 3 | Equity 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 liabilities in the Consolidated Statements of Financial Condition.

Fair Value - Unobservable Input

Fair Value - Unobservable Inputs Used In The Valuation of CDOs (Details) - CDOs	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Minimum
Fair Value (Details) - Assets Measured At Fair Value On A Non-Recurring Basis [Line Items]
Probability of prepayment	0.00%	0.00%
Probability of default	16.50%	16.70%
Loss given default	93.40%	93.30%
Probability of deferral cure	0.00%	7.60%
Maximum
Fair Value (Details) - Assets Measured At Fair Value On A Non-Recurring Basis [Line Items]
Probability of prepayment	11.40%	10.90%
Probability of default	44.80%	46.80%
Loss given default	99.20%	98.90%
Probability of deferral cure	100.00%	100.00%

Fair Value - Carrying Value of

Fair Value - Carrying Value of CDOs (Details) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2017USD ($)security	Mar. 31, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Rollforward of the Carrying Value of CDOs [Roll Forward]
Carrying Value of CDOs sold			$ 210,200
CDOs
Rollforward of the Carrying Value of CDOs [Roll Forward]
Beginning balance		$ 33,454	$ 33,260	$ 30,431	$ 33,260	$ 31,529
Change in other comprehensive income	[1]	(739)		1,794	(604)	764
Other		(1,889)		(326)	(1,830)	(394)
Ending balance		$ 30,826		$ 31,899	$ 30,826	$ 31,899
Number Of Securities Sold | security		3
Carrying Value of CDOs sold		$ 1,900
[1]	Included in unrealized holding gains in the Consolidated Statements of Comprehensive Income.

Fair Value - Significant Unobse

Fair Value - Significant Unobservable Inputs Used In the Valuation of MSRs (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Total amount of loans being serviced for the benefit of others at the end of the period	$ 616.7	$ 640.5
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	8.80%	7.70%
Maturity (months)	7 months	12 months
Discount rate	9.50%	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	26.20%	22.80%
Maturity (months)	91 months	103 months
Discount rate	13.00%	13.00%

Fair Value - Carrying Value o88

Fair Value - Carrying Value of Mortgage Servicing Rights (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance		$ 5,925	$ 4,938	$ 6,120	$ 1,853
Additions from acquisition		0	0	0	3,092
New MSRs		161	581	522	928
Total losses included in earnings:
Changes in valuation inputs and assumptions	[1]	(121)	(205)	(209)	(377)
Other changes in fair value	[1],[2]	(199)	(238)	(667)	(420)
Ending balance		5,766	5,076	5,766	5,076
Contractual servicing fees earned	[1]	$ 379	$ 373	$ 1,158	$ 922
[1]	Included in mortgage banking income in the Condensed Consolidated Statements of Income and related to assets held as of September 30, 2017 and 2016.
[2]	Primarily represents changes in expected future cash flows due to payoffs and paydowns.

Fair Value - Assets Measured At

Fair Value - Assets Measured At Fair Value On A Non-Recurring Basis (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Fair Value (Details) - Assets Measured At Fair Value On A Non-Recurring Basis [Line Items]
OREO		$ 19,873	$ 26,083
Nonrecurring | Level 1
Fair Value (Details) - Assets Measured At Fair Value 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
Nonrecurring | Level 2
Fair Value (Details) - Assets Measured At Fair Value 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
Nonrecurring | Level 3
Fair Value (Details) - Assets Measured At Fair Value On A Non-Recurring Basis [Line Items]
Collateral-dependent impaired loans	[1]	19,265	22,019
OREO	[2]	8,304	8,624
Loans held-for-sale	[3]	17,508	10,484
Assets held-for-sale	[4]	$ 9,157	$ 4,075
[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 - Financial Instrume

Fair Value - Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Cash and due from banks	$ 174,147	$ 155,055
Interest-bearing deposits in other banks	252,753	107,093
Securities held-to-maturity	14,638	22,291
FHLB and FRB stock	69,708	59,131
Loans	10,295,478	8,168,062
Investment in BOLI	279,639	219,746
Liabilities:
Deposits	11,208,497	8,828,603
Borrowed funds	700,536	879,008
Senior and subordinated debt	195,028	194,603
Carrying Amount | Level 1
Assets:
Cash and due from banks	174,147	155,055
Carrying Amount | Level 2
Assets:
Interest-bearing deposits in other banks	252,753	107,093
Securities held-to-maturity	14,638	22,291
FHLB and FRB stock	69,708	59,131
Liabilities:
Deposits	11,208,497	8,828,603
Borrowed funds	700,536	879,008
Senior and subordinated debt	195,028	194,603
Accrued interest payable	3,336	3,416
Carrying Amount | Level 3
Assets:
Loans	10,299,094	8,172,584
Investment in BOLI	279,639	219,746
Accrued interest receivable	43,697	34,384
Other interest-earning assets	327	834
Fair Value | Level 1
Assets:
Cash and due from banks	174,147	155,055
Fair Value | Level 2
Assets:
Interest-bearing deposits in other banks	252,753	107,093
Securities held-to-maturity	12,921	18,212
FHLB and FRB stock	69,708	59,131
Liabilities:
Deposits	11,195,159	8,820,572
Borrowed funds	700,536	879,008
Senior and subordinated debt	194,449	197,888
Accrued interest payable	3,336	3,416
Fair Value | Level 3
Assets:
Loans	10,048,553	7,973,845
Investment in BOLI	279,639	219,746
Accrued interest receivable	43,697	34,384
Other interest-earning assets	$ 327	$ 834

Fair Value - Narrative (Details

Fair Value - Narrative (Details)	Sep. 30, 2017
Minimum
Fair Value (Details) [Line Items]
Appraisal adjustment (percent)	0.00%
Maximum
Fair Value (Details) [Line Items]
Appraisal adjustment (percent)	15.00%