MB Financial 10-Q 10 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 10, 2018
Document and Entity Information
Entity Registrant Name	MB FINANCIAL INC /MD
Entity Central Index Key	1,139,812
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock shares outstanding		84,065,578
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks	$ 332,234	$ 397,880
Interest earning deposits with banks	50,624	181,341
Total cash and cash equivalents	382,858	579,221
Investment securities:
Securities available for sale, at fair value	1,679,011	1,408,326
Securities held to maturity, at amortized cost ($950,806 fair value at March 31, 2018 and $992,455 at December 31, 2017)	933,319	959,082
Marketable equity securities, at fair value	11,124	0
Non-marketable securities - FHLB and FRB stock	118,955	114,111
Total investment securities	2,742,409	2,481,519
Loans held for sale	561,549	548,578
Loans:
Total loans, excluding purchased credit-impaired loans	13,824,990	13,846,318
Purchased credit-impaired loans	109,990	119,744
Total loans	13,934,980	13,966,062
Less: Allowance for loan and lease losses	161,712	157,710
Net loans	13,773,268	13,808,352
Lease investments, net	408,798	409,051
Premises and equipment, net	281,791	286,690
Cash surrender value of life insurance	204,710	203,602
Goodwill	1,003,548	1,003,548
Other intangibles	52,864	54,766
Mortgage servicing rights, at fair value	291,561	276,279
Other real estate owned, net	10,528	9,736
Other real estate owned related to FDIC-assisted transactions	4,185	4,788
Other assets	449,454	420,810
Total assets	20,167,523	20,086,940
Deposits:
Non-interest bearing	6,385,149	6,381,512
Interest bearing	8,585,444	8,576,866
Total deposits	14,970,593	14,958,378
Short-term borrowings	717,679	861,039
Long-term borrowings	851,221	505,158
Junior subordinated notes issued to capital trusts	194,304	211,494
Accrued expenses and other liabilities	499,379	541,048
Total liabilities	17,233,176	17,077,117
STOCKHOLDERS’ EQUITY
Preferred stock, ($0.01 par value, authorized 10,000,000 shares at March 31, 2018 and December 31, 2017; Series A, 8% perpetual non-cumulative, none issued and outstanding at March 31, 2018 and 4,000,000 shares issued and outstanding at December 31, 2017, $25 liquidation value; Series C, 6% perpetual non-cumulative, 200,000 shares issued and outstanding at March 31, 2018 and December 31, 2017, $1,000 liquidation value)	194,719	309,999
Common stock, ($0.01 par value; authorized 120,000,000 shares at March 31, 2018 and December 31, 2017; issued 85,974,387 shares at March 31, 2018 and 85,801,702 shares at December 31, 2017)	860	858
Additional paid-in capital	1,692,650	1,691,007
Retained earnings	1,112,323	1,065,303
Accumulated other comprehensive (loss) income	(3,719)	3,584
Less: 1,921,840 and 1,883,810 shares of treasury common stock, at cost, at March 31, 2018 and December 31, 2017, respectively	(62,486)	(60,928)
Total stockholders’ equity	2,934,347	3,009,823
Total liabilities and stockholders’ equity	$ 20,167,523	$ 20,086,940

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Securities held to maturity, at amortized cost, fair value	$ 950,806	$ 992,455
Preferred stock, par or stated value per share (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	120,000,000	120,000,000
Common stock, issued shares (in shares)	85,974,387	85,801,702
Treasury stock, shares (in shares)	1,921,840	1,883,810
Series A Preferred Stock
Preferred stock, dividend rate (percent)	8.00%	8.00%
Preferred stock, shares issued (in shares)	4,000,000	4,000,000
Preferred stock, shares outstanding (in shares)	4,000,000	4,000,000
Preferred stock, liquidation preference per share (in dollars per share)	$ 25	$ 25
Series C Preferred Stock
Preferred stock, dividend rate (percent)	8.00%	8.00%
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, liquidation preference per share (in dollars per share)	$ 1,000	$ 1,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Loans:
Taxable	$ 157,119	$ 133,737
Nontaxable	2,271	2,880
Investment securities:
Taxable	7,934	9,122
Nontaxable	9,476	9,973
Other interest earning accounts and Federal funds sold	131	199
Total interest income	176,931	155,911
Interest expense:
Deposits	15,032	7,475
Short-term borrowings	2,516	2,380
Long-term borrowings and junior subordinated notes	6,002	3,013
Total interest expense	23,550	12,868
Net interest income	153,381	143,043
Provision for credit losses	7,508	3,734
Net interest income after provision for credit losses	145,873	139,309
Non-interest income:
Mortgage banking revenue	25,047	28,456
Lease financing revenue, net	24,710	21,418
Treasury management fees	15,156	14,689
Wealth management fees	9,121	8,520
Card fees	4,787	4,566
Capital markets and international banking fees	2,998	3,253
Consumer and other deposit service fees	2,912	3,363
Brokerage fees	864	1,125
Loan service fees	2,245	1,969
Increase in cash surrender value of life insurance	1,108	1,288
Net (loss) gain on investment securities	(174)	231
Net loss on disposal of other assets	(357)	(123)
Other operating income	4,385	3,695
Total non-interest income	92,802	92,450
Non-interest expenses:
Salaries and employee benefits expense	106,514	101,551
Occupancy and equipment expense	17,429	15,044
Computer services and telecommunication expense	11,156	9,440
Advertising and marketing expense	3,863	3,161
Professional and legal expense	1,898	2,691
Other intangibles amortization expense	1,902	2,090
Branch exit and facilities impairment charges	0	(682)
Net loss recognized on other real estate owned and other related expenses	47	844
Loss on extinguishment of debt	3,136	0
Other operating expenses	21,941	22,203
Total non-interest expenses	167,886	156,342
Income before income taxes	70,789	75,417
Income tax expense	14,032	20,880
Net income	56,757	54,537
Dividends on preferred shares	3,100	2,003
Return from preferred stockholders due to redemption	(15,280)	0
Net income available to common stockholders	$ 68,937	$ 52,534
Common share data:
Basic earnings per common share (in dollars per share)	$ 0.82	$ 0.63
Diluted earnings per common share (in dollars per share)	$ 0.81	$ 0.62
Weighted average common shares outstanding for basic earnings per common share (in shares)	84,065,681	83,662,430
Diluted weighted average common shares outstanding for diluted earnings per common share (in shares)	84,896,401	84,778,130

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 56,757	$ 54,537
Unrealized holding (gains) losses on investment securities, net of reclassification adjustments	(12,092)	6,054
Reclassification adjustment for amortization of unrealized losses (gains) on investment securities transferred to held to maturity from available for sale	151	(473)
Reclassification adjustments for losses (gains) included in net income	174	(231)
Other comprehensive (loss) income, before tax	(11,767)	5,350
Income tax expense (benefit) related to items of other comprehensive (loss) income	3,128	(2,125)
Other comprehensive (loss) income, net of tax	(8,639)	3,225
Comprehensive income	$ 48,118	$ 57,762

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss), Net of Tax	Treasury Stock	Non-controlling Interest
Beginning balance at Dec. 31, 2016	$ 2,579,209	$ 115,572	$ 856	$ 1,678,826	$ 838,892	$ 5,190	$ (60,384)	$ 257
Increase (Decrease) in Stockholders' Equity
Net income	54,537				54,537
Other comprehensive income (loss), net of tax	3,225					3,225
Cash dividends declared on preferred shares	(2,003)				(2,003)
Cash dividends declared on common shares	(16,131)				(16,131)
Restricted common stock activity, net of tax	(3,321)			(6,870)			3,549
Stock option activity, net of tax	(199)		1	(200)
Repurchase of common shares in connection with employee benefit plans and held in trust for deferred compensation plan	(2,543)			289			(2,832)
Stock-based compensation expense	4,481			4,481
Purchase of additional investment in subsidiary from minority owners	(827)			(570)				(257)
Ending balance at Mar. 31, 2017	2,616,428	115,572	857	1,675,956	875,295	8,415	(59,667)	0
Increase (Decrease) in Stockholders' Equity
Cumulative effect of accounting changes	(298)				(1,634)	1,336
Beginning balance at Dec. 31, 2017	3,009,823	309,999	858	1,691,007	1,065,303	3,584	(60,928)
Increase (Decrease) in Stockholders' Equity
Net income	56,757				56,757
Other comprehensive income (loss), net of tax	(8,639)					(8,639)
Redemption of preferred stock	(100,000)	(115,280)			15,280
Cash dividends declared on preferred shares	(3,100)				(3,100)
Cash dividends declared on common shares	(20,283)				(20,283)
Restricted common stock activity, net of tax	(3,204)		1	(3,205)
Stock option activity, net of tax	165		1	164
Repurchase of common shares in connection with employee benefit plans and held in trust for deferred compensation plan	(1,325)			233			(1,558)
Stock-based compensation expense	4,451			4,451
Ending balance at Mar. 31, 2018	$ 2,934,347	$ 194,719	$ 860	$ 1,692,650	$ 1,112,323	$ (3,719)	$ (62,486)	$ 0

CONSOLIDATED STATEMENTS OF CHA7

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends declared (in dollars per share)	$ 0.24	$ 0.19

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows From Operating Activities
Net income	$ 56,757	$ 54,537
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of premises and equipment and leased equipment	27,950	21,797
Branch exit and facilities impairment charges	0	(682)
Compensation expense for share-based payment plans	4,451	4,481
Net loss (gain) on sales of premises and equipment and leased equipment	419	(576)
Amortization of other intangibles	1,902	2,090
Provision for credit losses	7,508	3,734
Deferred income tax expense	19,591	18,304
Amortization of premiums and discounts on investment securities, net	8,337	10,738
Accretion of discounts on loans, net	(4,749)	(7,158)
Net loss (gain) on investment securities	174	(231)
Proceeds from sale of loans held for sale	1,026,096	1,305,445
Origination of loans held for sale	(1,055,406)	(1,073,357)
Net loss (gain) on sale of loans held for sale	9,840	(4,052)
Origination of mortgage servicing rights	(12,340)	(15,651)
Change in fair value of mortgage servicing rights	(2,875)	2,660
Net (gain) loss on other real estate owned	(143)	607
Increase in cash surrender value of life insurance	(1,108)	(1,288)
Loss on extinguishment of debt	3,136	0
Increase (decrease) in other assets, net	(25,045)	68,066
Decrease in other liabilities, net	(63,549)	(97,061)
Net cash provided by operating activities	946	292,403
Cash Flows From Investing Activities
Proceeds from sales of investment securities available for sale		9,911
Proceeds from maturities and calls of investment securities available for sale	94,273	71,539
Purchases of investment securities available for sale	(391,866)	(45,791)
Proceeds from maturities and calls of investment securities held to maturity	38,502	31,896
Purchases of investment securities held to maturity	(12,859)	(15,150)
Purchase of marketable equity securities	(250)	0
Purchases of non-marketable securities - FHLB and FRB stock	(14,971)	(53,307)
Redemption of non-marketable securities - FHLB and FRB stock	10,127	52,156
Net decrease (increase) in loans	31,591	(179,104)
Purchases of mortgage servicing rights	(67)	(496)
Purchases of premises and equipment and leased equipment	(26,364)	(28,361)
Proceeds from sales of premises and equipment and leased equipment	4,272	5,976
Proceeds from sale of other real estate owned	1,442	11,324
Proceeds from sale of other real estate owned related to FDIC-assisted transactions	838	1,420
Purchase of additional investment in subsidiary from minority owners	0	(827)
Net proceeds from FDIC related covered assets	183	(434)
Net cash used in investing activities	(265,149)	(139,248)
Cash Flows From Financing Activities
Net increase (decrease) in deposits	12,215	(111,065)
Proceeds from short-term borrowings - FHLB advances	140,000	1,000,000
Principal paid on short-term borrowings - FHLB advances	(475,000)	(1,050,000)
Net increase (decrease) in short-term borrowings	191,640	(43,660)
Proceeds from long-term borrowings	439,676	89,060
Principal paid on long-term borrowings	(93,613)	(10,232)
Redemption of junior subordinated notes issued to capital trusts	(20,619)	0
Redemption of preferred stock	(100,000)	0
Treasury stock transactions, net	(1,325)	(2,543)
Stock options exercised	659	610
Dividends paid on preferred stock	(5,100)	(2,003)
Dividends paid on common stock	(20,693)	(16,385)
Net cash provided by (used in) financing activities	67,840	(146,218)
Net (decrease) increase in cash and cash equivalents	(196,363)	6,937
Cash and cash equivalents:
Beginning of period	579,221	463,469
End of period	382,858	470,406
Cash payments for:
Interest paid to depositors and on other borrowed funds	21,656	12,687
Income tax payments, net	1,172	1,700
Supplemental Schedule of Noncash Investing Activities:
Investment securities held to maturity purchased not settled	2,861	6,386
Loans transferred to other real estate owned	2,296	350
Loans transferred to repossessed assets	797	489
Operating leases rewritten as direct finance leases included as loans	2,359	1,339
Long-term borrowings transferred to short-term borrowings	75,000	75,000
Adjustments to noncash assets previously acquired:
Loans	0	1,846
Goodwill	0	(1,113)
Other assets	0	(733)
Total adjustments to noncash assets previously acquired	$ 0	$ 0

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation These unaudited consolidated financial statements include the accounts of MB Financial, Inc., a Maryland corporation (the “Company”), and its subsidiaries, including its wholly owned national bank subsidiary, MB Financial Bank, N.A. (“MB Financial Bank”), based in Chicago, Illinois. In the opinion of management, all normal recurring adjustments necessary for a fair presentation of the financial condition, results of operations and cash flows for the interim periods have been made. The results of operations for the three months ended March 31, 2018 are not necessarily indicative of the results to be expected for the entire fiscal year. These unaudited interim financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and industry practice. Certain information in footnote disclosure normally included in financial statements prepared in accordance with U.S. GAAP and industry practice has been condensed or omitted pursuant to rules and regulations of the Securities and Exchange Commission. These financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions which affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, as well as the reported amounts of income and expenses during the reported periods. Actual results could differ from those estimates. Certain prior period amounts have been reclassified to conform to current period presentation. These reclassifications did not result in any changes to previously reported net income or stockholders’ equity.

New Authoritative Accounting Gu

New Authoritative Accounting Guidance	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
New Authoritative Accounting Guidance	New Authoritative Accounting Guidance ASC Topic 805 "Business Combinations." New authoritative accounting guidance under ASC Topic 805 "Business Combinations" amends prior guidance to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 606 "Revenue from Contracts with Customers." New authoritative accounting guidance under ASC Topic 606, "Revenue from Contracts with Customers" amended prior guidance to require 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. The new authoritative guidance was initially effective for reporting periods after January 1, 2017 but was deferred to January 1, 2018. The Company's revenue is comprised of interest income on financial assets, which is excluded from the scope of this new guidance, and non-interest income. This new guidance changes how certain recurring revenue streams are recognized within lease financing revenue and insignificant components of non-interest income. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. See "Accounting changes" below. ASC Topic 825 "Financial Instruments." New authoritative accounting guidance under ASC Topic 825 "Financial Instruments" amended prior guidance to require equity investments (except those accounted for under the equity method of accounting) to be measured at fair value with changes in fair value recognized in net income. An entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer. The new guidance simplifies the impairment assessment of equity investments without readily determinable fair values, requires public entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from changes in the instrument-specific credit risk when the entity has selected the fair value option for financial instruments and requires separate presentation of financial assets and liabilities by measurement category and form of financial asset. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. See "Accounting changes" below. ASC Topic 405 "Liabilities-Extinguishment of Liabilities." New authoritative accounting guidance under ASC Topic 405, "Liabilities-Extinguishment of Liabilities" amended prior guidance to clarify that liabilities related to the sale of prepaid store-value products within the scope of this guidance are financial liabilities and that breakage for those liabilities are to be accounted for consistent with the breakage guidance in ASC Topic 606 "Revenue from Contracts with Customers." The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 842 "Leases." New authoritative accounting guidance under ASC Topic 842 "Leases" amended prior guidance to require lessees to recognize the assets and liabilities arising from all leases on the balance sheet. The new authoritative guidance defines a lease as a contract, or part of a contract, that conveys the right to control the use of identified property, plant, or equipment (an identified asset) for a period of time in exchange for consideration. In addition, the qualifications for a sale and leaseback transaction have been amended. The new authoritative guidance also requires qualitative and quantitative disclosures by lessees and lessors to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The new authoritative guidance will be effective for reporting periods after January 1, 2019. The Financial Accounting Standards Board issued a proposal in January 2018 to provide an additional transition method that would allow entities to not apply this new guidance in the comparative periods presented in the financial statements and instead recognize a cumulative effect adjustment to the beginning retained earnings at the date of application. The Company is evaluating the new guidance and its impact on the Company's statements of operations and financial condition. The Company expects an increase in assets and liabilities as a result of recording additional lease contracts where the Company is lessee. ASC Topic 815 "Derivatives and Hedging." New authoritative accounting guidance under ASC Topic 815 "Derivatives and Hedging" amended prior guidance to better align an entity's risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The new authoritative guidance expands and refines hedge accounting for both nonfinancial and financial risk components. The new authoritative guidance will be effective for reporting periods after January 1, 2019 with early adoption permitted. This new authoritative guidance is not expected to have a significant impact on the Company's statements of operations or financial condition. ASC Topic 718 "Compensation - Stock Compensation." New authoritative accounting guidance under ASC Topic 718 "Compensation - Stock Compensation" amends prior guidance by clarifying which changes to terms or conditions of a share-based payment award require an entity to apply modification accounting. An entity should account for the effects of a modification unless the fair value, vesting conditions and classification of the modified award are the same as the original award. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 326 "Financial Instruments - Credit Losses." New authoritative accounting guidance under ASC Topic 326 " Financial Instruments - Credit Losses " amended the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information for credit loss estimates. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The new authoritative guidance also requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected (net of the allowance for credit losses). In addition, the credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses rather than a write-down. The new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company is evaluating the new guidance and expects it to have an impact on the Company's statements of operations and financial condition, the significance of which is not yet known nor can it be reasonably estimated currently. Due to the significant differences in the new authoritative guidance from existing GAAP, the implementation of this guidance may result in material changes in our accounting for credit losses on the financial instruments and will be impacted by the Company's loan and securities portfolios' composition, attributes, and quality in addition to the prevailing economic conditions and forecasts at the time of adoption. As part of the Company's evaluation process, it has established a steering committee and working group, including individuals from various functional areas, to assess processes and related controls, portfolio segmentation, model development, system requirements, and needed resources. The Company is also considering third-party consultants to assist in the evaluation process. ASC Topic 230 "Statement of Cash Flows." New authoritative accounting guidance under ASC Topic 230 "Statement of Cash Flows" addresses eight specific cash flow classification issues with the objective of reducing the existing diversity in practice. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. New authoritative accounting guidance under ASC Topic 230 "Statement of Cash Flows" amends prior guidance to require an entity to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the statement of cash flows. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 740 "Income Taxes." New authoritative accounting guidance under ASC Topic 740 "Income Taxes" amends prior guidance to require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 350 "Intangibles-Goodwill and Other." New authoritative accounting guidance under ASC Topic 350 "Intangibles-Goodwill and Other" amends prior guidance to eliminate Step 2 from the goodwill impairment test and require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company is evaluating the new guidance and its impact on the Company's statements of operations and financial condition. ASC Topic 610 "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets." New authoritative accounting guidance under ASC Topic 610 "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets" amends prior guidance to clarify the scope of Subtopic 610-20 by defining in substance nonfinancial assets and to add guidance for partial sales of nonfinancial assets. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 310 "Receivables - Nonrefundable Fees and Other Costs." New authoritative accounting guidance under ASC Topic 310 "Receivables - Nonrefundable Fees and Other Costs" amends prior guidance by shortening the amortization period for certain callable debt securities held at a premium requiring the premium to be amortized to the earliest call date. The new authoritative guidance will be effective for reporting periods after January 1, 2019 with early adoption permitted. The Company is evaluating the new guidance and its impact on the Company's statements of operations and financial condition. ASC Topic 220 "Income Statement - Reporting Comprehensive Income." New authoritative accounting guidance under ASC Topic 220 "Income Statement - Reporting Comprehensive Income" allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from enactment of H.R. 1, originally known as the "Tax Cuts and Jobs Act." The new authoritative guidance will be effective for reporting periods after January 1, 2019 with early adoption permitted. The Company early adopted the new guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. See "Accounting changes" below. Accounting changes . The Company adopted the new authoritative accounting guidance under ASC Topic 606, "Revenue from Contracts with Customers" on January 1, 2018 using the modified retrospective transition method for contracts that were not completed at the date of initial application. The Company recognized a cumulative effect reduction to the beginning retained earnings totaling $683 thousand . This amount relates to lease financing revenue where the Company's performance obligation is over time. Previously, such revenue was recognized immediately. See " Lease financing revenue, net " below . The new authoritative accounting guidance under ASC Topic 606 requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. To achieve this, the Company takes the following steps: identify the contract(s) with a customer; identify the performance obligations in the contract; determine the transaction price; allocate the transaction price to the performance obligations in the contract; and recognize revenue when (or as) the Company satisfies a performance obligation. The non-interest revenue streams that are considered to be in the scope of this new guidance are discussed below. Lease financing revenue, net. Fees from the sale of third-party equipment maintenance contracts are included within lease financing revenue, net. The Company sells third-party equipment maintenance contracts and provides customers with an asset and maintenance contract management tool over the life of the maintenance contract. Since the Company provides support for the asset and maintenance contract management tool, the Company's performance obligation is satisfied over the life of the maintenance contract, and the fees are recognized monthly over the life of the maintenance contract. Payment is typically received at the time of sale of the maintenance contract. Treasury management fees and consumer and other deposit service fees. Deposit related fees (account analysis fees, monthly service fees, and other related fees) are included within treasury management fees and consumer and other deposit service fees. The Company's performance obligation is ongoing and either party may cancel at any time. These fees are generally recognized as the services are rendered on a monthly basis. Payment is typically received monthly. Wealth management fees. Wealth management fees include revenue from the management and advisement of client assets and trust administration. The Company's performance obligation is generally satisfied over time, and the fees are recognized monthly. Payment is typically received quarterly or annually. Card fees. Card fees include debit and credit card interchange fees and ATM fees. For debit and credit card transactions, the Company considers the merchant as the customer for interchange revenue with the performance obligation being satisfied when the cardholder purchases goods or services from the merchant. Interchange revenue is recognized as the services are provided. The Company's performance obligation for ATM fees is satisfied when services are provided, and the fees are recognized at that time. Payment is typically received immediately or in the following month. Capital markets and international banking fees. Capital markets and international banking fees include M&A advisory and syndication fees. The Company's performance obligation is generally satisfied over time, and the fees are recognized monthly. For M&A advisory fees, a portion of the payment is received at the beginning of the engagement with the remainder once the transaction is completed. For syndication fees, payment is received annually. The Company also adopted the new authoritative accounting guidance under ASC Topic 825 "Financial Instruments" and ASC Topic 220 "Income Statement - Reporting Comprehensive Income" on January 1, 2018. The Company recognized a cumulative effect increase to the beginning retained earnings and accumulated other comprehensive income totaling $385 thousand under ASC Topic 825 representing the fair value adjustment to equity securities at the date of initial application. In addition, the Company reclassified $1.2 million from accumulated other comprehensive loss to retained earnings for the stranded tax effects resulting from enactment of the Tax Cuts and Jobs Act at the date of initial application of the new guidance under ASC Topic 220.

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share Earnings per common share is computed using the two-class method. Basic earnings per common share is computed by dividing net income available to common stockholders by the weighted-average number of common shares outstanding during the applicable period, excluding outstanding participating securities. Participating securities include non-vested restricted stock awards and restricted stock units, though no actual shares of common stock related to restricted stock units are issued until the settlement of such units, to the extent holders of these securities receive non-forfeitable dividends or dividend equivalents at the same rate as holders of the Company's common stock. Diluted earnings per common share is computed using the weighted-average number of shares determined for the basic earnings per common share computation plus the dilutive effect of stock compensation using the treasury stock method. The following table presents a reconciliation of the number of shares used in the calculation of basic and diluted earnings per common share (amounts in thousands, except share and per share data). Three Months Ended March 31, 2018 2017 Distributed earnings allocated to common stock $ 20,283 $ 16,131 Undistributed earnings 36,474 38,406 Net income 56,757 54,537 Less: preferred stock dividends 3,100 2,003 Plus: return from preferred stockholders due to redemption (1) 15,280 — Net income available to common stockholders for basic earnings per common share 68,937 52,534 Plus: preferred stock dividends on convertible preferred stock — 3 Less: earnings allocated to participating securities 2 1 Earnings allocated to common stockholders for diluted earnings per common share $ 68,935 $ 52,536 Weighted average shares outstanding for basic earnings per common share 84,065,681 83,662,430 Dilutive effect of: Stock options 507,786 636,515 Restricted shares and units 322,934 471,863 Convertible preferred stock — 7,322 Total dilutive effect of equity awards and convertible preferred stock 830,720 1,115,700 Weighted average shares outstanding for diluted earnings per common share 84,896,401 84,778,130 Basic earnings per common share $ 0.82 $ 0.63 Diluted earnings per common share 0.81 0.62 (1) Represents the excess carrying amount over the redemption price of the 8% Series A non-cumulative perpetual preferred stock redeemed in the first quarter of 2018.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities Amortized cost and fair value of investment securities, excluding marketable equity securities and non-marketable FHLB and FRB stock, were as follows as of the dates indicated (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value March 31, 2018 Available for Sale U.S. Government sponsored agencies and enterprises $ 22,948 $ — $ (63 ) $ 22,885 States and political subdivisions 355,058 12,478 (630 ) 366,906 Residential mortgage-backed securities 1,202,251 2,331 (17,514 ) 1,187,068 Commercial mortgage-backed securities 64,144 227 (210 ) 64,161 Corporate bonds 38,020 1 (30 ) 37,991 Total Available for Sale 1,682,421 15,037 (18,447 ) 1,679,011 Held to Maturity States and political subdivisions 874,306 18,704 (1,910 ) 891,100 Residential mortgage-backed securities 59,013 693 — 59,706 Total Held to Maturity 933,319 19,397 (1,910 ) 950,806 Total $ 2,615,740 $ 34,434 $ (20,357 ) $ 2,629,817 December 31, 2017 Available for Sale U.S. Government sponsored agencies and enterprises $ 23,013 $ 3 $ (9 ) $ 23,007 States and political subdivisions 363,813 15,998 (486 ) 379,325 Residential mortgage-backed securities 861,594 3,035 (11,930 ) 852,699 Commercial mortgage-backed securities 71,554 612 (131 ) 72,035 Corporate bonds 70,155 84 (42 ) 70,197 Equity securities (1) 11,236 — (173 ) 11,063 Total Available for Sale 1,401,365 19,732 (12,771 ) 1,408,326 Held to Maturity States and political subdivisions 878,400 32,559 (447 ) 910,512 Residential mortgage-backed securities 80,682 1,261 — 81,943 Total Held to Maturity 959,082 33,820 (447 ) 992,455 Total $ 2,360,447 $ 53,552 $ (13,218 ) $ 2,400,781 (1) Reflected in marketable equity securities on the consolidated balance sheet following the adoption of the new guidance under ASC Topic 825 "Financial Instruments" on January 1, 2018. The increase in investment securities was due to investments in residential mortgage-backed securities in the first quarter of 2018. The Company has no direct exposure to the State of Illinois in its investment securities portfolio, but approximately 19% of the state and political subdivisions portfolio consisted of securities issued by municipalities located in Illinois as of March 31, 2018 . Approximately 95% of the state and political subdivisions securities were general obligation issues, and 26% were insured or had another form of credit enhancement as of March 31, 2018 . Unrealized losses on investment securities by length of time in a continuous unrealized loss position and the fair value of the related securities at March 31, 2018 were as follows (in thousands): Less Than 12 Months 12 Months or More Total Fair Unrealized Fair Unrealized Fair Unrealized Value Losses Value Losses Value Losses Available for Sale U.S. Government sponsored agencies and enterprises $ 22,885 $ (63 ) $ — $ — $ 22,885 $ (63 ) States and political subdivisions 18,110 (69 ) 18,586 (561 ) 36,696 (630 ) Residential mortgage-backed securities 442,766 (4,035 ) 390,083 (13,479 ) 832,849 (17,514 ) Commercial mortgage-backed securities 32,416 (136 ) 11,322 (74 ) 43,738 (210 ) Corporate bonds 19,044 (12 ) 9,980 (18 ) 29,024 (30 ) Total Available for Sale 535,221 (4,315 ) 429,971 (14,132 ) 965,192 (18,447 ) Held to Maturity States and political subdivisions 158,964 (1,455 ) 11,631 (455 ) 170,595 (1,910 ) Total $ 694,185 $ (5,770 ) $ 441,602 $ (14,587 ) $ 1,135,787 $ (20,357 ) Unrealized losses on investment securities by length of time in a continuous unrealized loss position and the fair value of the related securities at December 31, 2017 were as follows (in thousands): Less Than 12 Months 12 Months or More Total Fair Unrealized Fair Unrealized Fair Unrealized Value Losses Value Losses Value Losses Available for Sale U.S. Government sponsored agencies and enterprises $ 5,111 $ (9 ) $ — $ — $ 5,111 $ (9 ) States and political subdivisions 9,016 (29 ) 18,754 (457 ) 27,770 (486 ) Residential mortgage-backed securities 256,769 (1,853 ) 407,224 (10,077 ) 663,993 (11,930 ) Commercial mortgage-backed securities 19,483 (20 ) 14,583 (111 ) 34,066 (131 ) Corporate bonds 7,052 (8 ) 9,963 (34 ) 17,015 (42 ) Equity securities 11,063 (173 ) — — 11,063 (173 ) Total Available for Sale 308,494 (2,092 ) 450,524 (10,679 ) 759,018 (12,771 ) Held to Maturity States and political subdivisions 45,499 (257 ) 12,561 (190 ) 58,060 (447 ) Total $ 353,993 $ (2,349 ) $ 463,085 $ (10,869 ) $ 817,078 $ (13,218 ) The total number of security positions in the investment portfolio in an unrealized loss position at March 31, 2018 was 630 compared to 471 at December 31, 2017 . This increase in total number of security positions in a continuous unrealized loss position from December 31, 2017 to March 31, 2018 was mainly attributable to the mortgage-backed securities in the investment securities portfolio. Declines in the fair value of available for sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses to the extent the impairment is related to credit losses. The amount of the impairment related to other factors is recognized in other comprehensive income. In estimating other-than-temporary impairment losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) whether the Company is more likely than not to sell the security before recovery of its cost basis. As of March 31, 2018 , management does not have the intent to sell any of the securities in the table above and believes that it is more likely than not that the Company will not have to sell any such securities before a recovery of cost. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Accordingly, as of March 31, 2018 , management believes the impairments detailed in the table above are temporary. Changes in market interest rates can significantly influence the fair value of securities, and the fair value of our municipal securities portfolio would decline substantially if interest rates increase materially. Net gains (losses) recognized on investment securities were as follows (in thousands): Three Months Ended March 31, 2018 2017 Realized gains $ 88 $ 237 Realized losses (262 ) (6 ) Net (losses) gains $ (174 ) $ 231 The amortized cost and fair value of investment securities as of March 31, 2018 by contractual maturity are shown below. Maturities may differ from contractual maturities in mortgage-backed securities because the mortgages underlying the securities may be called or repaid without any penalties. Therefore, mortgage-backed securities are not included in the maturity categories in the following maturity summary. Amortized Fair (In thousands) Cost Value Available for sale: Due in one year or less $ 87,751 $ 87,946 Due after one year through five years 142,875 147,296 Due after five years through ten years 38,869 39,263 Due after ten years 146,531 153,277 Residential and commercial mortgage-backed securities 1,266,395 1,251,229 1,682,421 1,679,011 Held to maturity: Due in one year or less 45,415 45,629 Due after one year through five years 176,545 182,455 Due after five years through ten years 207,875 213,927 Due after ten years 444,471 449,089 Residential mortgage-backed securities 59,013 59,706 933,319 950,806 Total $ 2,615,740 $ 2,629,817 Investment securities with a carrying amount of $679.1 million at March 31, 2018 and $726.1 million at December 31, 2017 were pledged as collateral on public deposits and for other purposes as required or permitted by law, while only $587.0 million and $625.2 million were required to be pledged at March 31, 2018 and December 31, 2017 , respectively. Investment securities held to maturity with a carrying amount of $2.6 million were transferred to the available for sale portfolio and subsequently sold during the first quarter of 2018. These investment securities were obligations of states and political subdivisions that were downgraded and no longer met our credit criteria.

Loans

Loans	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loans	Loans Loans consist of the following at (in thousands): March 31, December 31, Commercial loans $ 4,790,803 $ 4,786,180 Commercial loans collateralized by assignment of lease payments 2,095,189 2,113,135 Commercial real estate 4,093,045 4,147,529 Residential real estate 1,391,900 1,432,458 Construction real estate 479,638 406,849 Indirect vehicle 692,642 667,928 Home equity 202,920 219,098 Other consumer loans 78,853 73,141 Total loans, excluding purchased credit-impaired loans 13,824,990 13,846,318 Purchased credit-impaired loans 109,990 119,744 Total loans $ 13,934,980 $ 13,966,062 Loans are made to individuals as well as commercial and tax exempt entities. Specific loan terms vary as to interest rate, repayment, and collateral requirements based on the type of loan requested and the credit worthiness of the prospective borrower. Except for commercial loans collateralized by assignment of lease payments, asset-based loans, residential real estate loans, and indirect vehicle loans, credit risk tends to be geographically concentrated in that a majority of the loan customers are located in Illinois. The Company's extension of credit is governed by its Credit Risk Policy, which was established to control the quality of the Company's loans. This policy is reviewed and approved by the Enterprise Risk Committee of the Company's Board of Directors on an annual basis. Commercial Loans. Commercial credit is extended mostly to middle market customers. Such credits are typically comprised of working capital loans, loans for physical asset expansion, asset acquisition loans and other business loans. Loans to closely held businesses will generally be guaranteed in full or for a significant amount by the businesses' principal owners. Commercial loans are made based primarily on the historical cash flow of the borrower and secondarily on the underlying collateral provided by the borrower. The cash flows of borrowers, however, may not perform as forecasted and collateral securing loans may fluctuate in value due to economic or individual performance factors. Minimum standards and underwriting guidelines have been established for all commercial loan types. Asset-based loans, also included in commercial loans, are made to businesses with the primary source of repayment derived from payments on the related assets securing the loan. Collateral for these loans may include accounts receivable, inventory and equipment, and is monitored regularly to ensure ongoing sufficiency of collateral coverage and quality. The primary risk for these loans is a significant decline in collateral values due to general market conditions. Loan terms that mitigate these risks include typical industry amortization schedules, percentage of collateral advances, maintenance of cash collateral accounts and regular asset monitoring. Because of the national scope of our asset-based lending, the risk of these loans is also diversified by geography. Commercial Loans Collateralized by Assignment of Lease Payments ("Lease Loans"). The Company makes lease loans to lessors where the underlying leases are with both investment grade and non-investment grade companies. Investment grade lessees are companies rated in one of the four highest categories by Moody's Investor Services. Whether or not companies fall into this category, each lease loan is considered on its individual merit based on the financial wherewithal of the lessee using financial information available at the time of underwriting. In addition, leases that transfer substantially all of the benefits and risk related to the equipment ownership are classified as direct finance leases and are included in lease loans. Commercial Real Estate Loans. Commercial real estate loans are subject to underwriting standards and processes similar to commercial loans. These loans are viewed primarily as property income based loans and the repayment of these loans is largely dependent on the successful operation of the property, which also serves as collateral for the loan. In addition, $1.3 billion of commercial real estate loans at March 31, 2018 were secured by owner-occupied properties where the primary source of repayment is the cash flow from the ongoing operations and activities conducted by the owner of the property. Loan performance may be adversely affected by factors impacting the general economy or conditions specific to the real estate market such as geographic location and/or property type. Construction Real Estate Loans. The Company defines construction loans as loans where the loan proceeds are monitored by the Company and used exclusively for the improvement of real estate in which the Company holds a mortgage. Due to the inherent risk in this type of loan, these loans are subject to other industry specific policy guidelines outlined in the Company's Credit Risk Policy. Consumer Related Loans. The Company originates direct and indirect consumer loans, including residential real estate, home equity lines and loans, credit cards, and indirect vehicle loans (motorcycle, marine, recreational, and powersports vehicles). Each loan type is underwritten based upon several factors including debt to income, type of collateral and loan to collateral value, credit history, and the Company's relationship with the borrower. Indirect loan and credit card underwriting involves the use of risk-based pricing in the underwriting process. Purchased credit-impaired loans. Purchased credit-impaired loans are accounted for under ASC Topic 310-30, which include purchased credit-impaired loans acquired through business combinations, FDIC-assisted transactions and re-purchase transactions with the Government National Mortgage Association ("GNMA"). The loans re-purchased from GNMA were originally sold by the Company with servicing retained and subsequently became delinquent. These loans are also insured by the Federal Housing Administration (commonly referred to as "FHA") or the U.S. Department of Veterans Affairs (commonly referred to as "VA") where the Company would be able to recover the principal balance of these loans. All re-purchases from GNMA are at the Company's discretion. Pledged loans. A collateral pledge agreement exists whereby at all times, the Company must keep on hand, free of all other pledges, liens, and encumbrances, loans with unpaid principal balances aggregating no less than 160% for qualifying first mortgage loans, 170% for home equity loans, 161% for qualifying commercial real estate loans and 106% for loans held for sale, of the outstanding advances from the Federal Home Loan Bank. As of March 31, 2018 and December 31, 2017 , the Company had $4.6 billion and $4.7 billion , respectively, of loans pledged as collateral for long-term Federal Home Loan Bank advances and third party letters of credit, while only $3.4 billion and $3.1 billion were required to be pledged at March 31, 2018 and December 31, 2017 , respectively. The following table presents the contractual aging of the recorded investment in past due loans by class of loans as of March 31, 2018 and December 31, 2017 (in thousands): Current 30-59 Days 60-89 Days Loans Past Due Total Total March 31, 2018 Commercial $ 4,751,376 $ 30,468 $ 1,195 $ 7,764 $ 39,427 $ 4,790,803 Commercial collateralized by assignment of lease payments 2,066,953 22,462 5,073 701 28,236 2,095,189 Commercial real estate: Health care 757,936 — — — — 757,936 Industrial 867,979 2,718 — — 2,718 870,697 Multifamily 580,484 — — 164 164 580,648 Retail 482,646 835 — 229 1,064 483,710 Office 454,793 3,087 — 112 3,199 457,992 Other 937,356 3,704 80 922 4,706 942,062 Residential real estate 1,373,261 9,877 219 8,543 18,639 1,391,900 Construction real estate 479,066 572 — — 572 479,638 Indirect vehicle 687,508 3,646 1,026 462 5,134 692,642 Home equity 197,141 1,397 1,077 3,305 5,779 202,920 Other consumer 78,615 112 71 55 238 78,853 Total loans, excluding purchased credit-impaired loans 13,715,114 78,878 8,741 22,257 109,876 13,824,990 Purchased credit-impaired loans 63,071 10,559 2,685 33,675 46,919 109,990 Total loans $ 13,778,185 $ 89,437 $ 11,426 $ 55,932 $ 156,795 $ 13,934,980 Non-performing loan aging $ 30,610 $ 6,296 $ 2,157 $ 22,257 $ 30,710 $ 61,320 December 31, 2017 Commercial $ 4,769,244 $ 1,702 $ 6,926 $ 8,308 $ 16,936 $ 4,786,180 Commercial collateralized by assignment of lease payments 2,099,246 11,320 1,878 691 13,889 2,113,135 Commercial real estate: Health care 710,722 — — — — 710,722 Industrial 908,394 — — 755 755 909,149 Multifamily 601,844 688 — 732 1,420 603,264 Retail 503,224 — — 474 474 503,698 Office 453,960 — 956 1,454 2,410 456,370 Other 956,181 7,035 76 1,034 8,145 964,326 Residential real estate 1,410,473 12,359 1,907 7,719 21,985 1,432,458 Construction real estate 404,595 2,254 — — 2,254 406,849 Indirect vehicle 661,028 4,905 1,083 912 6,900 667,928 Home equity 210,831 3,161 1,073 4,033 8,267 219,098 Other consumer 72,846 202 36 57 295 73,141 Total loans, excluding purchased credit-impaired loans 13,762,588 43,626 13,935 26,169 83,730 13,846,318 Purchased credit-impaired loans 63,937 8,749 3,997 43,061 55,807 119,744 Total loans $ 13,826,525 $ 52,375 $ 17,932 $ 69,230 $ 139,537 $ 13,966,062 Non-performing loan aging $ 36,879 $ 8,799 $ 4,961 $ 26,169 $ 39,929 $ 76,808 The following table presents the recorded investment in non-accrual loans and loans past due ninety days or more and still accruing by class of loans, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Loans past due Loans past due Non-accrual 90 days or more and still accruing Non-accrual 90 days or more and still accruing Commercial $ 12,654 $ 150 $ 14,001 $ 3,500 Commercial collateralized by assignment of lease payments 672 367 490 531 Commercial real estate: Health care 5,394 — — — Industrial 3,433 — 8,807 — Multifamily 277 — 860 — Office 458 — 2,772 — Retail 286 — 590 — Other 1,129 9 8,016 190 Residential real estate 19,353 362 18,374 1,210 Construction real estate — — — — Indirect vehicle 3,149 5 3,019 81 Home equity 13,338 225 14,305 — Other consumer 8 51 4 58 Total $ 60,151 $ 1,169 $ 71,238 $ 5,570 The Company utilizes an internal asset classification system as a means of reporting problem and potential problem loans. Under the Company's risk rating system, the Company classifies potential problem and problem loans as “Special Mention,” “Substandard,” and “Doubtful.” Substandard loans include those characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. Loans classified as Doubtful have all the weaknesses inherent in those classified as Substandard with the added characteristic that the weaknesses present make collection or liquidation in full, on the basis of currently existing facts, conditions and values, highly questionable and improbable. Loans that do not currently expose the Company to sufficient risk to warrant classification in one of the aforementioned categories but possess weaknesses that deserve management's close attention are deemed to be Special Mention. Loans rated but not adversely classified are deemed to be Pass. Risk ratings are updated any time the situation warrants and at least annually. Loans not rated are included in groups of homogeneous loans with similar risk and loss characteristics and are not included in the table below. The following tables present the risk category of loans by class of loans based on the most recent analysis performed, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): Pass Special Substandard Doubtful Total March 31, 2018 Commercial $ 4,503,362 $ 164,489 $ 122,952 $ — $ 4,790,803 Commercial collateralized by assignment of lease payments 2,075,740 13,828 5,621 — 2,095,189 Commercial real estate: Health care 684,542 13,156 60,238 — 757,936 Industrial 851,429 11,627 7,641 — 870,697 Multifamily 578,352 858 1,438 — 580,648 Retail 472,397 9,109 2,204 — 483,710 Office 452,559 4,975 458 — 457,992 Other 872,138 37,948 31,976 — 942,062 Construction real estate 479,638 — — — 479,638 Total $ 10,970,157 $ 255,990 $ 232,528 $ — $ 11,458,675 December 31, 2017 Commercial $ 4,535,111 $ 147,232 $ 103,837 $ — $ 4,786,180 Commercial collateralized by assignment of lease payments 2,095,668 7,527 9,940 — 2,113,135 Commercial real estate: Health care 640,751 33,672 36,299 — 710,722 Industrial 885,524 12,411 11,214 — 909,149 Multifamily 595,818 146 7,300 — 603,264 Retail 492,830 8,326 2,542 — 503,698 Office 452,902 696 2,772 — 456,370 Other 891,703 37,682 34,941 — 964,326 Construction real estate 406,849 — — — 406,849 Total $ 10,997,156 $ 247,692 $ 208,845 $ — $ 11,453,693 Approximately $24.3 million and $35.6 million of the substandard loans were non-performing as of March 31, 2018 and December 31, 2017 , respectively. For residential real estate, home equity, indirect vehicle and other consumer loan classes, the Company also evaluates credit quality based on the aging status of the loan, which was previously presented, and by payment activity. The following table presents the recorded investment in those loan classes based on payment activity, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): Performing Non-performing Total March 31, 2018 Residential real estate $ 1,372,185 $ 19,715 $ 1,391,900 Indirect vehicle 689,488 3,154 692,642 Home equity 189,357 13,563 202,920 Other consumer 78,794 59 78,853 Total $ 2,329,824 $ 36,491 $ 2,366,315 December 31, 2017 Residential real estate $ 1,412,874 $ 19,584 $ 1,432,458 Indirect vehicle 664,828 3,100 667,928 Home equity 204,793 14,305 219,098 Other consumer 73,079 62 73,141 Total $ 2,355,574 $ 37,051 $ 2,392,625 The recorded investment in residential mortgage loans secured by residential real estate properties (including purchased credit-impaired loans) for which foreclosure proceedings are in process totaled $51.4 million and $43.6 million at March 31, 2018 and December 31, 2017 , respectively. The following tables present loans individually evaluated for impairment by class of loans, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Three Months Ended Unpaid Recorded Partial Allowance for Average Interest With no related allowance recorded: Commercial $ 6,055 $ 5,513 $ 542 $ — $ 7,067 $ — Commercial collateralized by assignment of lease payments — — — — — — Commercial real estate: Health care — — — — — — Industrial — — — — — — Multifamily — — — — — — Retail — — — — — — Office — — — — — — Other 3,309 3,309 — — 3,325 52 Residential real estate 3,432 3,394 38 — 3,394 — Construction real estate — — — — — — Indirect vehicle 424 209 215 — 479 7 Home equity — — — — — — Other consumer — — — — — — With an allowance recorded: Commercial 7,020 7,020 — 2,815 4,925 19 Commercial collateralized by assignment of lease payments — — — — — — Commercial real estate: Health care 5,394 5,394 — 2,979 1,083 28 Industrial 3,433 3,433 — 1,497 2,917 4 Multifamily — — — — — — Retail — — — — — — Office — — — — — — Other — — — — — — Residential real estate 21,766 19,313 2,453 1,996 19,311 1 Construction real estate — — — — — — Indirect vehicle — — — — — — Home equity 32,136 29,661 2,475 1,937 29,681 10 Other consumer — — — — — — Total $ 82,969 $ 77,246 $ 5,723 $ 11,224 $ 72,182 $ 121 December 31, 2017 Year Ended Unpaid Recorded Partial Allowance for Average Interest With no related allowance recorded: Commercial $ 8,312 $ 7,771 $ 541 $ — $ 5,595 $ 95 Commercial collateralized by assignment of lease payments — — — — 301 — Commercial real estate: Health care — — — — — — Industrial — — — — 1,260 8 Multifamily — — — — 1,261 29 Retail — — — — 814 27 Office 527 527 — — 1,426 18 Other 10,597 10,597 — — 2,312 128 Residential real estate 1,950 1,912 38 — 483 — Construction real estate — — — — — — Indirect vehicle 408 202 206 — 411 26 Home equity 81 81 — — 376 — Other consumer — — — — — — With an allowance recorded: Commercial 7,418 7,418 — 2,315 7,668 277 Commercial collateralized by assignment of lease payments — — — — 126 14 Commercial real estate: Health care — — — — — — Industrial 8,339 8,317 22 2,669 3,215 171 Multifamily 568 568 — 320 426 — Retail — — — — 1,345 28 Office 2,293 2,277 16 752 636 4 Other — — — — 29 — Residential real estate 21,380 19,014 2,366 2,158 17,616 25 Construction real estate — — — — — — Indirect vehicle — — — — — — Home equity 30,762 28,286 2,476 2,200 27,982 54 Other consumer — — — — — — Total $ 92,635 $ 86,970 $ 5,665 $ 10,414 $ 73,282 $ 904 Impaired loans included accruing restructured loans of $28.6 million that have been modified and are performing in accordance with those modified terms as of March 31, 2018 and December 31, 2017 . In addition, impaired loans included $28.5 million and $30.8 million of non-performing restructured loans as of March 31, 2018 and December 31, 2017 , respectively. Loans may be restructured in an effort to maximize collections from financially distressed borrowers. We use various restructuring techniques, including, but not limited to, deferring past due interest or principal, implementing an A/B note structure, redeeming past due taxes, reducing interest rates, extending maturities and modifying amortization schedules. Residential real estate loans are restructured in an effort to minimize losses while allowing borrowers to remain in their primary residences when possible. A loan classified as a troubled debt restructuring will no longer be included in the troubled debt restructuring disclosures in the years after the restructuring if the loan performs in accordance with the terms specified by the restructuring agreement and the interest rate specified in the restructuring agreement represents a market rate at the time of modification. The specified interest rate is considered a market rate when the interest rate is equal to or greater than the rate the Company is willing to accept at the time of restructuring for a new loan with comparable risk. If there are concerns that the borrower will not be able to meet the modified terms of the loan, the loan will continue to be included in the troubled debt restructuring disclosures. Impairment analyses on commercial-related loans classified as troubled debt restructurings are performed in conjunction with the normal allowance for loan and lease losses process. Consumer loans classified as troubled debt restructurings are aggregated in two pools that share common risk characteristics, home equity and residential real estate loans, with impairment measured on a quarterly basis based on the present value of expected future cash flows discounted at the loan's effective interest rate. The following table presents loans that were restructured during the three months ended March 31, 2018 (dollars in thousands): March 31, 2018 Number of Pre-Modification Recorded Post-Modification Recorded Charge-offs and Performing: Residential real estate 1 $ 88 $ 88 $ 9 Total 1 $ 88 $ 88 $ 9 Non-Performing: Residential real estate 8 $ 1,506 $ 1,506 $ 786 Indirect vehicle 11 67 67 2 Home equity 3 134 134 9 Total 22 $ 1,707 $ 1,707 $ 797 The following table presents loans that were restructured during the three months ended March 31, 2017 (dollars in thousands): March 31, 2017 Number of Pre-Modification Recorded Post-Modification Recorded Charge-offs and Performing: Residential real estate 3 $ 409 $ 409 $ 49 Home equity 1 33 33 3 Total 4 $ 442 $ 442 $ 52 Non-Performing: Residential real estate 9 $ 1,257 $ 1,257 $ 154 Indirect vehicle 3 20 20 4 Total 12 $ 1,277 $ 1,277 $ 158 Of the troubled debt restructurings entered into during the past twelve months, none subsequently defaulted during the three months ended March 31, 2018 . Performing troubled debt restructurings are considered to have defaulted when they become 90 days or more past due post-restructuring or are placed on non-accrual status. The following table presents the troubled debt restructurings activity during the three months ended March 31, 2018 (in thousands): Performing Non-performing Beginning balance $ 28,554 $ 30,836 Additions 88 1,707 Charge-offs — (20 ) Principal payments, net (1,471 ) (1,660 ) Removals (77 ) (852 ) Transfer to other real estate owned — — Transfers in 1,962 465 Transfers out (465 ) (1,962 ) Ending balance $ 28,591 $ 28,514 Loans removed from troubled debt restructuring status are those that were restructured in a previous calendar year at a market rate of interest and have performed in compliance with the modified terms. The following table presents the type of modification for loans that have been restructured during the three months ended March 31, 2018 (in thousands): March 31, 2018 Extended Maturity, Delay in Amortization Extended Payments and/or and Reduction Maturity and/or Reduction of of Interest Rate Amortization Interest Rate Total Residential real estate $ 1,256 $ 252 $ 86 $ 1,594 Indirect vehicle — — 67 67 Home equity — 134 — 134 Total $ 1,256 $ 386 $ 153 $ 1,795 The following table presents the activity in the allowance for credit losses, balance in allowance for credit losses and recorded investment in loans by portfolio segment and based on impairment method as of March 31, 2018 and 2017 (in thousands): Commercial Commercial collateralized by assignment of lease payments Commercial real estate Residential real estate Construction real estate Indirect vehicle Home equity Other consumer Unfunded commitments Total March 31, 2018 Allowance for credit losses: Three Months Ended Beginning balance $ 46,267 $ 13,007 $ 63,429 $ 7,012 $ 15,501 $ 4,728 $ 5,296 $ 2,470 $ 1,698 $ 159,408 Charge-offs 1,402 — 2,476 701 — 1,824 64 351 — 6,818 Recoveries 337 251 762 70 393 1,179 70 230 — 3,292 Provision 349 (265 ) 4,083 (5 ) 3,909 267 (956 ) 146 (20 ) 7,508 Ending balance $ 45,551 $ 12,993 $ 65,798 $ 6,376 $ 19,803 $ 4,350 $ 4,346 $ 2,495 $ 1,678 $ 163,390 Ending allowance balance attributable to loans: Individually evaluated for impairment $ 2,815 $ — $ 4,476 $ 1,996 $ — $ — $ 1,937 $ — $ 563 $ 11,787 Collectively evaluated for impairment 42,662 12,993 60,497 4,380 19,768 4,350 2,409 2,495 1,115 150,669 Acquired and accounted for under ASC 310-30 (1) 74 — 825 — 35 — — — — 934 Total ending allowance balance $ 45,551 $ 12,993 $ 65,798 $ 6,376 $ 19,803 $ 4,350 $ 4,346 $ 2,495 $ 1,678 $ 163,390 Loans: Individually evaluated for impairment $ 12,533 $ — $ 12,136 $ 22,707 $ — $ 209 $ 29,661 $ — $ — $ 77,246 Collectively evaluated for impairment 4,778,270 2,095,189 4,080,909 1,369,193 479,638 692,433 173,259 78,853 — 13,747,744 Acquired and accounted for under ASC 310-30 (1) 10,877 — 24,648 57,633 4,980 — 10,483 1,369 — 109,990 Total ending loans balance $ 4,801,680 $ 2,095,189 $ 4,117,693 $ 1,449,533 $ 484,618 $ 692,642 $ 213,403 $ 80,222 $ — $ 13,934,980 March 31, 2017 Allowance for credit losses: Three Months Ended Beginning balance $ 44,661 $ 12,238 $ 51,807 $ 5,971 $ 14,758 $ 3,421 $ 5,469 $ 1,041 $ 2,476 $ 141,842 Charge-offs 168 — 1,085 90 — 1,411 173 446 — 3,373 Recoveries 1,510 463 518 528 112 652 283 229 — 4,295 Provision (5,313 ) (558 ) 6,980 1,722 (11 ) 962 (267 ) 367 (148 ) 3,734 Ending balance $ 40,690 $ 12,143 $ 58,220 $ 8,131 $ 14,859 $ 3,624 $ 5,312 $ 1,191 $ 2,328 $ 146,498 Ending allowance balance attributable to loans: Individually evaluated for impairment $ 986 $ — $ 286 $ 2,192 $ — $ — $ 2,634 $ — $ 541 $ 6,639 Collectively evaluated for impairment 39,545 12,143 57,799 5,939 14,824 3,624 2,678 1,191 1,787 139,530 Acquired and accounted for under ASC 310-30 (1) 159 — 135 — 35 — — — — 329 Total ending allowance balance $ 40,690 $ 12,143 $ 58,220 $ 8,131 $ 14,859 $ 3,624 $ 5,312 $ 1,191 $ 2,328 $ 146,498 Loans: Individually evaluated for impairment $ 15,214 $ 729 $ 10,160 $ 15,803 $ — $ 108 $ 28,437 $ — $ — $ 70,451 Collectively evaluated for impairment 4,348,908 2,007,872 3,724,011 1,211,415 554,942 573,684 218,368 80,016 — 12,719,216 Acquired and accounted for under ASC 310-30 (1) 24,768 — 46,683 77,332 5,624 — 12,382 2,025 — 168,814 Total ending loans balance $ 4,388,890 $ 2,008,601 $ 3,780,854 $ 1,304,550 $ 560,566 $ 573,792 $ 259,187 $ 82,041 $ — $ 12,958,481 (1) Loans acquired in business combinations and accounted for under ASC Subtopic 310-30 “Receivables — Loans and Debt Securities Acquired with Deteriorated Credit Quality.” Purchased loans acquired in a business combination are recorded at estimated fair value on their purchase date without a carryover of the related allowance for loan and lease losses. These acquired loans are segregated into three types: pass rated loans with no discount attributable to credit quality, non-impaired loans with a discount attributable at least in part to credit quality and impaired loans with evidence of significant credit deterioration. • Pass rated loans (typically performing loans) are accounted for in accordance with ASC Topic 310-20 "Nonrefundable Fees and Other Costs" as these loans do not have evidence of credit deterioration since origination. • Non-impaired loans (typically performing substandard loans) are accounted for in accordance with ASC Topic 310-30 if they display at least some level of credit deterioration since origination. • Impaired loans (typically substandard loans on non-accrual status) are accounted for in accordance with ASC Topic 310-30 as they display significant credit deterioration since origination. For pass rated loans (non-purchased credit-impaired loans), the difference between the estimated fair value of the loans and the principal outstanding is accreted over the remaining life of the loans. In accordance with ASC 310-30, for both purchased non-impaired loans and purchased credit-impaired loans, the loans are pooled by loan type and the difference between contractually required payments at acquisition and the cash flows expected to be collected is referred to as the non-accretable difference. Further, any excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable yield and is recognized into interest income over the remaining life of the loan pools when there is a reasonable expectation about the amount and timing of such cash flows. Substantially all of the loans acquired in FDIC-assisted transactions displayed at least some level of credit deterioration and as such are included as non-impaired and impaired loans as described immediately above. During the three months ended March 31, 2018 , there was a negative provision for credit losses of $413 thousand and net recoveries of $170 thousand in relation to purchased credit-impaired loans. There was $934 thousand and $1.2 million in allowance for loan and lease losses related to these purchased credit-impaired loans at March 31, 2018 and December 31, 2017 , respectively. The provision for credit losses and accompanying charge-offs are included in the table above. Changes in the accretable yield for loans acquired and accounted for under ASC 310-30 were as follows for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended March 31, 2018 2017 Balance at beginning of period $ 12,069 $ 16,050 Purchases — 43 Accretion (2,411 ) (2,188 ) Other (1) 609 1,006 Balance at end of period $ 10,267 $ 14,911 (1) Primarily includes discount transfers from non-accretable discount to accretable discount due to better than expected performance of loan pools acquired and accounted for under ASC 310-30. In our FDIC-assisted transactions, the fair value of purchased credit-impaired loans, on the acquisition date, was determined based on assigned risk ratings, expected cash flows and the fair value of loan collateral. The fair value of loans that were non-impaired was determined based on estimates of losses on defaults and other market factors. Due to the loss-share agreements with the FDIC, we recorded a receivable (FDIC indemnification asset) from the FDIC equal to the present value of the corresponding reimbursement percentages on the estimated losses embedded in the loan portfolio. For other loans acquired through business combinations, the fair value of purchased credit-impaired loans, on the acquisition date, was determined based on assigned risk ratings, expected cash flows and the fair value of loan collateral. The fair value of loans that were non-impaired was determined based on estimates of losses on defaults and other market factors. The carrying amount of loans acquired through a business combination by loan pool type are as follows (in thousands): March 31, 2018 Purchased Purchased Non-Credit-Impaired Total Covered loans (1) : Consumer related $ 14,449 $ — $ 14,449 Non-covered loans: Commercial loans 10,877 210,070 220,947 Commercial loans collateralized by assignment of lease payments — 30,534 30,534 Commercial real estate 24,648 703,127 727,775 Construction real estate 4,980 4,743 9,723 Consumer related 5,562 252,660 258,222 Total non-covered loans 46,067 1,201,134 1,247,201 Total acquired $ 60,516 $ 1,201,134 $ 1,261,650 (1) Covered loans refer to loans covered under loss-sharing agreements with the FDIC. The loss-share agreements expire between 2019 and 2020. In addition to loans acquired through a business combination noted in the table above, consumer related purchased credit-impaired loans includes loans repurchased from GNMA of $49.5 million as of March 31, 2018 .

Goodwill and Intangibles

Goodwill and Intangibles	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	Goodwill and Intangibles The excess of the cost of an acquisition over the fair value of the net assets acquired, including core deposit and client relationship intangibles, consists of goodwill. Under ASC Topic 350, goodwill is subject to at least annual assessments for impairment by applying a fair value based test. The Company reviews goodwill to determine potential impairment annually, or more frequently if events and circumstances indicate that goodwill might be impaired, by comparing the carrying value of the reporting units with the fair value of the reporting units. The Company's annual assessment date is as of December 31. Goodwill is tested for impairment at the reporting unit level. The Company has three reporting units: Banking, Leasing and Mortgage Banking. No impairment losses were recognized during the three months ended March 31, 2018 or 2017 . The carrying amount of goodwill was $1.0 billion at March 31, 2018 and December 31, 2017 . On April 12, 2018, the Company announced the discontinuation of its national mortgage origination business, which includes substantially all originations outside of the Company's consumer banking footprint in the Chicagoland area. As a result, the Company expects to record an impairment loss in the amount of $3.6 million in the second quarter of 2018. See "Note 17. Subsequent Event." The following table presents the carrying amount of goodwill by segment for the three months ended March 31, 2018 (in thousands): Banking Leasing Mortgage Banking Total Balance at end of period $ 959,285 $ 40,640 $ 3,623 $ 1,003,548 The Company has other intangible assets consisting of core deposit and client relationship intangibles that had a remaining weighted average amortization period of approximately 12 years as of March 31, 2018 . The following table presents the changes during the three months ended March 31, 2018 in the carrying amount of core deposit and client relationship intangibles, and the gross carrying amount, accumulated amortization, and net book value as of March 31, 2018 (in thousands): March 31, 2018 Balance at beginning of period $ 54,766 Amortization expense (1,902 ) Balance at end of period $ 52,864 Gross carrying amount $ 112,820 Accumulated amortization (59,956 ) Net book value $ 52,864 The following presents the estimated future amortization expense of other intangible assets (in thousands): Year ending December 31, Amount 2018 $ 5,549 2019 5,674 2020 5,022 2021 4,790 2022 3,806 Thereafter 28,023 $ 52,864

Deposits

Deposits	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Deposits	Deposits The composition of deposits was as follows as of March 31, 2018 and December 31, 2017 (in thousands): March 31, December 31, 2018 2017 Demand deposit accounts, non-interest bearing $ 6,385,149 $ 6,381,512 NOW, money market, and interest bearing deposits 4,858,506 4,954,765 Savings accounts 1,229,968 1,167,810 Certificates of deposit, $250,000 or more 1,519,552 1,506,071 Other certificates of deposit 977,418 948,220 Total $ 14,970,593 $ 14,958,378 Certificates of deposit of $250,000 or more included $1.1 billion of brokered deposits at March 31, 2018 and December 31, 2017 . Brokered deposits typically consist of smaller individual time certificates that have the same liquidity characteristics and yields consistent with time certificates of $250,000 or more.

Short-Term Borrowings

Short-Term Borrowings	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Short-Term Borrowings	Short-Term Borrowings Short-term borrowings were as follows as of March 31, 2018 and December 31, 2017 (dollars in thousands): March 31, 2018 December 31, 2017 Weighted Average Interest Rate Amount Weighted Average Interest Rate Amount Customer repurchase agreements 0.38 % $ 225,962 0.27 % $ 232,789 Federal Home Loan Bank advances 1.85 365,000 1.31 625,000 Federal funds purchased 1.69 126,717 1.26 3,250 Line of credit — — — — Total 1.36 % $ 717,679 1.03 % $ 861,039 Securities sold under agreements to repurchase are agreements in which the Company acquires funds by selling assets to another party under a simultaneous agreement to repurchase the same assets at a specified price and date. The Company enters into repurchase agreements and also offers a demand deposit account product to customers that sweeps their balances in excess of an agreed upon target amount into overnight repurchase agreements. All securities sold under agreements to repurchase are recorded on the face of the balance sheet. The Company pledges mortgage-backed securities as collateral for the repurchase agreements and may be required to provide additional collateral based on the fair value of those securities. The Company had Federal Home Loan Bank advances with a maturity date less than one year of $365.0 million at March 31, 2018 and $625.0 million at December 31, 2017 . At March 31, 2018 , the interest rate on the advances outstanding on that date had rates ranging from 1.35% to 2.05% with maturities from June 2018 to March 2019 . The Company has loans pledged as collateral on this FHLB advance. See Note 6. Loans of the notes to the consolidated financial statements. On December 18, 2015, the Company entered into a $35.0 million unsecured line of credit at the holding company level with a correspondent bank. Interest is payable at a rate of one month LIBOR + 1.75% . No borrowings under the line of credit were outstanding as of March 31, 2018 and December 31, 2017 . The line of credit is scheduled to mature on June 30, 2018.

Long-Term Borrowings

Long-Term Borrowings	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Long-Term Borrowings	Long-Term Borrowings Long-term borrowings were as follows as of March 31, 2018 and December 31, 2017 (dollars in thousands): March 31, 2018 December 31, 2017 Weighted Average Interest Rate Amount Weighted Average Interest Rate Amount Federal Home Loan Bank advances 2.24 % $ 591,266 1.73 % $ 231,317 Notes payable 4.21 87,017 4.14 90,807 Subordinated notes, net of issuance costs (1) 4.00 172,938 4.00 173,034 Term note — — 3.31 10,000 Total 2.80 % $ 851,221 2.97 % $ 505,158 (1) The amount decreased from December 31, 2017 as a result of an increase in issuance costs due to adjustments for actual costs. The Company had Federal Home Loan Bank ("FHLB") advances with remaining contractual maturities greater than one year of $591.3 million at March 31, 2018 and $231.3 million at December 31, 2017 . As of March 31, 2018 , the advances had interest rates ranging from 1.78% to 5.87% and maturities ranging from April 2019 to April 2035 . The Company has loans pledged as collateral on these FHLB advances. See Note 6. Loans of the notes to the consolidated financial statements. The Company had notes payable to banks totaling $73.1 million and $76.3 million at March 31, 2018 and December 31, 2017 , respectively, which as of March 31, 2018 , were accruing interest at rates ranging from 2.25% to 7.40% , with a weighted average rate of 4.36% . Lease investments includes equipment with an amortized cost of $87.5 million and $91.9 million at March 31, 2018 and December 31, 2017 , respectively, that is pledged as collateral on these notes. At March 31, 2018 , the Company also had $13.9 million in other secured borrowings (included in the notes payable above) with a weighted average rate of 3.44% . On August 24, 2016, the Company assumed a $16.0 million unsecured term loan at the holding company level with a correspondent bank through the merger of American Chartered Bancorp, Inc. ("American Chartered") with and into the Company on that date. Interest was payable at a rate of one month LIBOR + 1.75% , and the loan was to mature on June 30, 2020. Principal payments of $1.0 million were due quarterly until maturity. As of March 31, 2018 , nothing was outstanding on this loan as it was prepaid in full in the first quarter of 2018.

Junior Subordinated Notes Issue

Junior Subordinated Notes Issued to Capital Trusts	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Junior Subordinated Notes Issued to Capital Trusts	Junior Subordinated Notes Issued to Capital Trusts The Company has established statutory trusts for the sole purpose of issuing trust preferred securities and related trust common securities. The proceeds from such issuances were used by the trusts to purchase junior subordinated notes of the Company, which are the sole assets of each trust. Concurrently with the issuance of the trust preferred securities, the Company issued guarantees for the benefit of the holders of the trust preferred securities. The Company’s outstanding trust preferred securities qualify, and are treated by the Company, as Tier 2 regulatory capital. Prior to the completion of the American Chartered merger, the trust preferred securities qualified, and were treated by the Company, as Tier 1 regulatory capital. The Company owns all of the common securities of each trust. The trust preferred securities issued by each trust rank equally with the common securities in right of payment, except that if an event of default under the indenture governing the notes has occurred and is continuing, the preferred securities will rank senior to the common securities in right of payment. The table below summarizes the outstanding junior subordinated notes and the related trust preferred securities issued by each trust as of March 31, 2018 (in thousands): Coal City Capital Trust I MB Financial Capital Trust II MB Financial Capital Trust III MB Financial Capital Trust IV Junior Subordinated Notes: Principal balance $ 25,774 $ 36,083 $ 10,310 $ 20,619 Annual interest rate 3-mo LIBOR + 1.80% 3-mo LIBOR + 1.40% 3-mo LIBOR + 1.50% 3-mo LIBOR + 1.52% Stated maturity date September 1, 2028 September 15, 2035 September 23, 2036 September 15, 2036 Call date September 1, 2008 December 15, 2010 September 23, 2011 September 15, 2011 Trust Preferred Securities: Face Value $ 25,000 $ 35,000 $ 10,000 $ 20,000 Annual distribution rate 3-mo LIBOR + 1.80% 3-mo LIBOR + 1.40% 3-mo LIBOR + 1.50% 3-mo LIBOR + 1.52% Issuance date July 1998 August 2005 July 2006 August 2006 Distribution dates (1) Quarterly Quarterly Quarterly Quarterly MB Financial Capital Trust V MB Financial Capital Trust VI FOBB Statutory Trust III (2) TAYC Capital Trust II (3) Junior Subordinated Notes: Principal balance $ 30,928 $ 23,196 $ 5,155 $ 41,238 Annual interest rate 3-mo LIBOR + 1.30% 3-mo LIBOR + 1.30% 3-mo LIBOR + 2.80% 3-mo LIBOR + 2.68% Stated maturity date December 15, 2037 October 30, 2037 January 23, 2034 June 17, 2034 Call date December 15, 2012 October 30, 2012 January 23, 2009 June 17, 2009 Trust Preferred Securities: Face Value $ 30,000 $ 22,500 $ 5,000 $ 40,000 Annual distribution rate 3-mo LIBOR + 1.30% 3-mo LIBOR + 1.30% 3-mo LIBOR + 2.80% 3-mo LIBOR + 2.68% Issuance date September 2007 October 2007 December 2003 June 2004 Distribution dates (1) Quarterly Quarterly Quarterly Quarterly American Chartered Statutory Trust II (4) Junior Subordinated Notes: Principal balance $ 10,310 Annual interest rate 3-mo LIBOR + 2.75% Stated maturity date October 7, 2034 Call date October 7, 2009 Trust Preferred Securities: Face Value $ 10,000 Annual distribution rate 3-mo LIBOR + 2.75% Issuance date August 2004 Distribution dates (1) Quarterly (1) All distributions are cumulative and paid in cash. (2) FOBB Statutory Trust III was established by First Oak Brook Bancshares, Inc. (“FOBB”) prior to the Company's acquisition of FOBB in 2006, and the junior subordinated notes issued by FOBB to FOBB Statutory Trust III were assumed by the Company upon completion of the acquisition. (3) TAYC Capital Trust II was established by Taylor Capital Group, Inc. (“Taylor Capital”) prior to the Company's acquisition of Taylor Capital in 2014, and the junior subordinated notes issued by Taylor Capital to TAYC Capital Trust II were assumed by the Company upon completion of the acquisition. Principal balance and face value amounts associated with TAYC Capital Trust II do not include purchase accounting adjustments to such amounts, which in each case resulted in a remaining discount of $6.3 million at March 31, 2018 . (4) American Chartered Statutory Trust II was established by American Chartered prior to the Company's acquisition of American Chartered in August 2016, and the junior subordinated notes issued by American Chartered to American Chartered Statutory Trust II were assumed by the Company upon completion of the acquisition. Principal balance and face value amounts associated with American Chartered Statutory Trust II do not include acquisition accounting adjustments to such amounts, which in each case resulted in a remaining discount of $2.7 million at March 31, 2018 . The trust preferred securities are subject to mandatory redemption, in whole or in part, upon repayment of the junior subordinated notes at the stated maturity date or upon redemption. Each trust’s ability to pay amounts due on the trust preferred securities is solely dependent upon the Company making payment on the related junior subordinated notes. The Company’s obligation under the junior subordinated notes and other relevant trust agreements, in aggregate, constitute a full and unconditional guarantee by the Company of each trust’s obligations under the trust preferred securities issued by each trust. The Company has the right to defer payment of interest on the notes and, therefore, distributions on the trust preferred securities, for up to five years , but not beyond the stated maturity date in the table above. During any such deferral period, the Company may not pay cash dividends on its common or preferred stock and generally may not repurchase its common or preferred stock. On March 19, 2018, the Company redeemed the junior subordinated notes held by American Chartered Statutory Trust I and, as a result, all of the issued and outstanding three month LIBOR + 3.60% American Chartered Statutory Trust I capital (preferred) securities were concurrently redeemed. The aggregate liquidation amount of these trust preferred securities was $20.0 million . American Chartered Statutory Trust I was established by American Chartered prior to the Company's acquisition of American Chartered, and the junior subordinated notes issued by American Chartered to American Chartered Statutory Trust I were assumed by the Company upon completion of the acquisition. As a result, the Company recognized a $3.1 million loss on extinguishment of debt in the first quarter of 2018.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments: The Company is a party to credit-related financial instruments with off-balance-sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit, standby letters of credit, and commercial letters of credit. Such commitments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the consolidated balance sheets. The Company’s exposure to credit loss is represented by the contractual amount of these commitments. The Company follows the same credit policies in making commitments as it does for on-balance-sheet instruments. At March 31, 2018 and December 31, 2017 , the following financial instruments were outstanding, the contractual amounts of which represent off-balance sheet credit risk (in thousands): Contractual Amount March 31, 2018 December 31, 2017 Commitments to extend credit: Home equity lines $ 198,649 $ 203,922 Other commitments 3,965,840 4,073,044 Letters of credit: Standby 161,752 161,014 Commercial 666 2,248 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require a payment of a fee. The commitments for home equity lines of credit may expire without being drawn upon. Therefore, the total commitment amounts do not necessarily represent future cash requirements. The amount of collateral obtained, if it is deemed necessary by the Company, is based on management’s credit evaluation of the customer. The Company, in the normal course of its business, regularly offers standby and commercial letters of credit to its bank customers. Standby and commercial letters of credit are a conditional but irrevocable form of guarantee. Under letters of credit, the Company typically guarantees payment to a third party beneficiary upon the default of payment or nonperformance by the bank customer and upon receipt of complying documentation from that beneficiary. Both standby and commercial letters of credit may be issued for any length of time, but normally do not exceed a period of five years. These letters of credit may also be extended or amended from time to time depending on the bank customer’s needs. As of March 31, 2018 , the maximum remaining term for any standby letters of credit was December 31, 2025 . A fee is charged to the bank customer and is recognized as income over the life of the letter of credit, unless considered non-rebatable under the terms of a letter of credit application. At March 31, 2018 , the aggregate contractual amount of these letters of credit, which represents the maximum potential amount of future payments that the Company would be obligated to pay, decreased $844 thousand to $162.4 million from $163.3 million at December 31, 2017 . Of the $162.4 million in commitments outstanding at March 31, 2018 , approximately $43.4 million of the letters of credit have been issued or renewed since December 31, 2017 . Letters of credit issued on behalf of bank customers may be done on either a secured or unsecured basis. If a letter credit is secured, the collateral can take various forms including bank accounts, investments, fixed assets, inventory, accounts receivable or real estate. The Company takes the same care in making credit decisions and obtaining collateral when it issues letters of credit on behalf of its customers as it does when making other types of loans. As of March 31, 2018 , the Company had approximately $7.2 million in capital expenditure commitments outstanding which relate to various projects to renovate the corporate office space and branches. Concentrations of credit risk: As of March 31, 2018 , approximately 19% of our investments in securities issued by states and political subdivisions were within the state of Illinois. We did not hold any direct exposure to the state of Illinois as of March 31, 2018 . Our commitments to extend credit are primarily related to commercial credits. Standby letters of credit are granted primarily to commercial borrowers. Our asset-based loans are made to borrowers located throughout the United States. Lease banking provides banking services to lessors located throughout the United States. Our leasing subsidiaries originate leases to companies located throughout the United States. In addition, our mortgage segment and indirect vehicle lenders originate loans to borrowers located throughout the United States. Contingencies: In the normal course of business, the Company is involved in various legal proceedings. In the opinion of management, any liability resulting from pending proceedings would not be expected to have a material adverse effect on the Company’s consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements ASC Topic 820 defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability shall not be adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact and (iv) willing to transact. ASC Topic 820 requires the use of valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert expected future amounts, such as cash flows or earnings, to a single present value amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement cost). Valuation techniques should be consistently applied. Inputs to valuation techniques refer to the assumptions that market participants would use in pricing the asset or liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect the reporting entity's own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. In that regard, ASC Topic 820 establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows: Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date. Level 2: Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3: Significant unobservable inputs that reflect a reporting entity's own assumptions about the assumptions that market participants would use in pricing an asset or liability. A description of the valuation methodologies used for instruments measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality, the Company's creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. Our valuation methodologies may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While management believes the Company's valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Transfers between levels of the fair value hierarchy are recognized on the actual date of the event or circumstances that caused the transfer, which generally coincides with the Company's monthly and/or quarterly valuation process. Financial Instruments Recorded at Fair Value on a Recurring Basis Securities Available for Sale . The fair values of securities available for sale are determined by quoted prices in active markets, when available, and classified as Level 1. If quoted market prices are not available, the fair value is determined by matrix pricing, which is a mathematical technique widely used in the industry to value debt securities without relying exclusively on quoted prices for the specific securities but rather by relying on the securities' relationship to other benchmark quoted securities and classified as Level 2. In cases where significant credit valuation adjustments are incorporated into the estimation of fair value, reported amounts are classified as Level 3. The change in fair value is recorded through an adjustment to the statement of other comprehensive income. Marketable Equity Securities . The fair values of marketable equity securities are determined by quoted prices in active markets, when available, and classified as Level 1. The change in fair value is recorded through an adjustment to the statement of operations. Loans Held for Sale. Mortgage loans originated and held for sale in the secondary market are carried at fair value. The fair value of loans held for sale is determined using quoted secondary market prices and classified as Level 2. The change in fair value is recorded through an adjustment to the statement of operations. Loans. The Company has elected to record certain mortgage loans at fair value. The fair value of these loans is determined using quoted secondary market prices and classified as Level 2. The change in fair value is recorded through an adjustment to the statement of operations. Mortgage Servicing Rights. The Company has elected to record its mortgage servicing rights at fair value. Mortgage servicing rights do not trade in an active market with readily observable prices. Accordingly, the Company determines the fair value of mortgage servicing rights by estimating the fair value of the future cash flows associated with the mortgage loans being serviced. Key economic assumptions used in measuring the fair value of mortgage servicing rights include, but are not limited to, prepayment speeds, discount rates, delinquencies and cost to service. The assumptions used in the model are validated on a regular basis. The fair value is validated on a quarterly basis with an independent third party. Any material discrepancies between the internal model and the third party validation are investigated and resolved by an internal committee. Due to the nature of the valuation inputs, mortgage servicing rights are classified in Level 3 of the fair value hierarchy. The change in fair value is recorded through an adjustment to the statement of operations. Assets Held in Trust for Deferred Compensation and Associated Liabilities. Assets held in trust for deferred compensation are recorded at fair value and included in “Other Assets” on the consolidated balance sheets. These assets are invested in mutual funds and classified as Level 1. Deferred compensation liabilities, also classified as Level 1, are carried at the fair value of the obligation to the employee, which corresponds to the fair value of the invested assets. The change in fair value is recorded through an adjustment to the statement of operations. Derivatives . Currently, we use interest rate swaps to manage our interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative and classified as Level 2. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including LIBOR rate curves. The Company also obtains dealer quotations for these derivatives for comparative purposes to assess the reasonableness of the model valuations. In addition, the Company uses forward commitments to buy to-be-announced mortgage securities for which we do not intend to take delivery of the security and will enter into an offsetting position before physical delivery to lessen the price volatility of the mortgage servicing rights asset. Dealer quotations are used for these derivatives and are classified as Level 1. The Company also offers other derivatives, including foreign currency forward contracts and interest rate lock commitments, to our customers and offset our exposure from such contracts by purchasing other financial contracts, which are valued using market consensus prices. For certain interest rate lock commitments, the Company uses an external valuation model that relies on internally developed inputs to estimate the fair value of its interest rate lock commitments. This is based on unobservable inputs that reflect management’s assumptions and specific information about each borrower transaction and is classified in Level 3 of the hierarchy. The change in fair value is recorded through an adjustment to the statement of operations. The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 , segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) March 31, 2018 Financial assets Securities available for sale: U.S Government sponsored agencies and enterprises $ 22,885 $ — $ 22,885 $ — States and political subdivisions 366,906 — 366,577 329 Residential mortgage-backed securities 1,187,068 — 1,187,049 19 Commercial mortgage-backed securities 64,161 — 64,161 — Corporate bonds 37,991 — 37,991 — Marketable equity securities 11,124 11,124 — — Loans held for sale 561,549 — 561,549 — Loans 39,206 — 39,206 — Mortgage servicing rights 291,561 — — 291,561 Assets held in trust for deferred compensation 23,324 23,324 — — Derivative financial instruments 49,005 1,082 45,642 2,281 Financial liabilities Other liabilities (1) 23,324 23,324 — — Derivative financial instruments 46,181 2,130 44,051 — December 31, 2017 Financial assets Securities available for sale: U.S. Government sponsored agencies and enterprises $ 23,007 $ — $ 23,007 $ — States and political subdivisions 379,325 — 378,996 329 Residential mortgage-backed securities 852,699 — 852,665 34 Commercial mortgage-backed securities 72,035 — 72,035 — Corporate bonds 70,197 — 70,197 — Equity securities 11,063 11,063 — — Loans held for sale 548,578 — 548,578 — Loans 40,531 — 40,531 — Mortgage servicing rights 276,279 — — 276,279 Assets held in trust for deferred compensation 21,410 21,410 — — Derivative financial instruments 31,499 389 29,539 1,571 Financial liabilities Other liabilities (1) 21,410 21,410 — — Derivative financial instruments 40,296 1,072 39,224 — (1) Liabilities associated with assets held in trust for deferred compensation The following table presents additional information about the unobservable inputs used in the fair value measurement of financial assets measured on a recurring basis that were categorized within the Level 3 of the fair value hierarchy (fair value in thousands): Fair Value at March 31, 2018 Valuation Technique Unobservable Input Range States and political subdivisions $ 329 Discounted cash flows Credit assumption 40% - 45% Loss Residential mortgage-backed securities 19 Discounted cash flows Constant pre-payment rates (CPR) 1% - 3% Mortgage servicing rights 291,561 Discounted cash flows CPR 6.35% - 6.84% Discount rate 9.53 - 11.06 Maturity (months) 325 - 358 Delinquency rate 2.05 - 4.78 Costs to service $ 67 - $ 227 Additive delinquent costs to service $ 175 - $ 1,000 Derivative financial instruments (mortgage 2,281 Sales cash flows Expected closing ratio 70% - 95% interest rate lock commitments) Expected delivery price 93.12 bps - 106.62 bps Fair Value at December 31, 2017 Valuation Technique Unobservable Input Range States and political subdivisions $ 329 Discounted cash flows Credit assumption 40-45% Loss Residential mortgage-backed securities 34 Discounted cash flows Constant pre-payment rates (CPR) 1% - 3% Mortgage servicing rights 276,279 Discounted cash flows CPR 6.7% - 7.8% Discount rate 9.53 - 11.06 Maturity (months) 324 - 358 Delinquency rate 2.42 - 5.30 Costs to service $ 67 - $ 227 Additive delinquent costs to service $ 175 - $ 1,000 Derivative financial instruments (mortgage 1,571 Sales cash flows Expected closing ratio 70% - 95% interest rate lock commitments) Expected delivery price 97.38 bps - 106.87 bps The significant unobservable inputs used in the fair value measurement of the Company’s mortgage servicing rights include prepayment speeds, discount rates, maturities, delinquencies and cost to service. Significant increases in prepayment speeds, discount rates, delinquencies or cost to service would result in a significantly lower fair value measurement. Conversely, significant decreases in prepayment speeds, discount rates, delinquencies or costs to service would result in a significantly higher fair value measurement. With the exception of changes in delinquencies, which can change the cost to service, the unobservable inputs move independently of each other. Key economic assumptions used in the measuring of the fair value of the mortgage servicing rights and the sensitivity of the fair value to immediate adverse changes in those assumptions at March 31, 2018 are presented in the following table. This table does not take into account the derivatives used to economically hedge the mortgage servicing rights. (dollars in thousands, except for weighted average cost to service) March 31, 2018 Weighted average CPR 6.52 % Impact on fair value of 10% adverse change $ (8,500 ) Impact on fair value of 20% adverse change (16,583 ) Weighted average discount rate 9.82 % Impact on fair value of 10% adverse change $ (12,400 ) Impact on fair value of 20% adverse change (23,803 ) Weighted average delinquency rate 4.56 % Impact on fair value of 10% adverse change $ (3,960 ) Impact on fair value of 20% adverse change (6,298 ) Weighted average costs to service $ 91.25 Impact on fair value of 10% adverse change (5,454 ) Impact on fair value of 20% adverse change (10,908 ) The Company did not have any transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2018 . The Company's policy for determining transfers between levels occurs at the end of the reporting period when circumstances in the underlying valuation criteria change and result in transfer between levels. The following table presents additional information about financial assets measured at fair value on a recurring basis for which the Company used significant unobservable inputs (Level 3): Three Months Ended March 31, 2018 2017 2018 2017 2018 2017 (in thousands) Investment Securities Mortgage Servicing Rights Derivatives Balance, beginning of period $ 363 $ 544 $ 276,279 $ 238,011 $ 1,571 $ 3,160 Purchases — — 67 496 — — Originations — — 12,340 15,651 — — Included in earnings — — 2,875 (2,660 ) 710 2,451 Principal payments (15 ) (35 ) — — — — Sales — — — — — — Balance, ending of period $ 348 $ 509 $ 291,561 $ 251,498 $ 2,281 $ 5,611 Financial Instruments Recorded at Fair Value on a Nonrecurring Basis The Company may be required, from time to time, to measure certain financial assets and financial liabilities at fair value on a nonrecurring basis in accordance with U.S. GAAP. These include assets that are measured at the lower of cost or fair value that were recognized at fair value below cost at the end of the period. Impaired Loans. Loans for which it is probable that payment of interest and principal will not be made in accordance with the contractual terms of the loan agreement are considered impaired. Once a loan is identified as individually impaired, management measures impairment in accordance with ASC Topic 310. The fair value of impaired loans is estimated using one of several methods, including collateral value, market value of similar debt, enterprise value, liquidation value, and discounted cash flows. Those impaired loans not requiring an allowance represent loans for which the fair value of the expected repayments or collateral exceed the recorded investments in such loans. In accordance with ASC Topic 820, impaired loans where an allowance is established based on the fair value of collateral require classification in the fair value hierarchy. Collateral values are estimated using Level 3 inputs based on customized discounting criteria. For a majority of impaired real estate loans where an allowance is established based on the fair value of collateral ( 100% at March 31, 2018 ), the Company obtains a current external appraisal. Other valuation techniques are used as well, including internal valuations, comparable property analysis and contractual sales information. Non-Financial Assets and Non-Financial Liabilities Recorded at Fair Value The Company has no non-financial assets or non-financial liabilities measured at fair value on a recurring basis. Certain non-financial assets and non-financial liabilities measured at fair value on a non-recurring basis include foreclosed assets and non-financial long-lived assets. Other Real Estate and Repossessed Vehicles Owned (Foreclosed Assets). Foreclosed assets, upon initial recognition, are measured and reported at fair value through a charge-off to the allowance for loan and lease losses based upon the fair value of the foreclosed asset. The fair value of foreclosed assets, upon initial recognition, are estimated using Level 3 inputs based on customized discounting criteria. Non-Financial Long-Lived Assets. Non-financial long-lived assets, when determined to be impaired, are measured and reported at fair value using Level 3 inputs based on customized discounting criteria. Assets measured at fair value on a nonrecurring basis as of March 31, 2018 and December 31, 2017 are included in the table below (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) March 31, 2018 Financial assets: Impaired loans $ 58,717 $ — $ — $ 58,717 Non-financial assets: Foreclosed assets 15,374 — — 15,374 December 31, 2017 Financial assets: Impaired loans $ 60,569 $ — $ — $ 60,569 Non-financial assets: Foreclosed assets 15,113 — — 15,113 The following table presents additional information about the unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy (fair value in thousands): Fair Value at Valuation March 31, 2018 Technique Unobservable Input Range Impaired loans $ 58,717 Appraisal of collateral Appraisal adjustments - sales costs 5% - 10% Foreclosed assets 15,374 Appraisal of collateral Appraisal adjustments - sales costs 5% - 10% Fair Value at Valuation December 31, 2017 Technique Unobservable Input Range Impaired loans $ 60,569 Appraisal of collateral Appraisal adjustments - sales costs 5% - 10% Foreclosed assets 15,113 Appraisal of collateral Appraisal adjustments - sales costs 5% - 10% ASC Topic 825 requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis. The methodologies for estimating the fair value of financial assets and financial liabilities that are measured at fair value on a recurring or non-recurring basis are discussed above. The estimated fair value approximates carrying value for cash and cash equivalents, accrued interest and the cash surrender value of life insurance policies. The methodologies for other financial assets and financial liabilities are discussed below: The following methods and assumptions were used by the Company in estimating the fair values of its other financial instruments: Cash and due from banks and interest earning deposits with banks: The carrying amounts reported in the balance sheet approximate fair value. Securities held to maturity: The fair values of securities held to maturity are determined by quoted prices in active markets, when available, and classified as Level 1. If quoted market prices are not available, the fair value is determined by matrix pricing, which is a mathematical technique widely used in the industry to value debt securities without relying exclusively on quoted prices for the specific securities but rather by relying on the securities' relationship to other benchmark quoted securities and classified as Level 2. In cases where significant credit valuation adjustments are incorporated into the estimation of fair value, reported amounts are classified as Level 3. Non-marketable securities - FHLB and FRB Stock: The carrying amounts reported in the balance sheet approximate fair value. Loans : The fair values for loans are estimated using discounted cash flow analyses, using the corporate bond curve adjusted for liquidity for commercial loans and the swap curve adjusted for liquidity for retail loans, including increased interest rate spreads to incorporate a credit mark, estimating an exit price. Non-interest bearing deposits : The fair values disclosed are equal to their balance sheet carrying amounts, which represent the amount payable on demand. Interest bearing deposits : The fair values disclosed for deposits with no defined maturities are equal to their carrying amounts, which represent the amounts payable on demand. Fair values for certificates of deposit are estimated using a discounted cash flow calculation that applies the Company's current incremental borrowing rates for similar terms. Short-term borrowings : The carrying amounts of federal funds purchased, borrowings under repurchase agreements and other short-term borrowings with maturities of 90 days or less approximate their fair values. The fair value of short-term borrowings greater than 90 days is based on the discounted value of contractual cash flows. Long-term borrowings : The fair values of the Company's long-term borrowings (other than deposits) are estimated using discounted cash flow analyses, based on the Company's current incremental borrowing rates for similar types of borrowing arrangements. Junior subordinated notes issued to capital trusts : The fair values of the Company's junior subordinated notes issued to capital trusts are estimated based on the quoted market prices, when available, of the related trust preferred security instruments, or are estimated based on the quoted market prices of comparable trust preferred securities. Accrued interest : The carrying amount of accrued interest receivable and payable approximate their fair values. Off-balance-sheet instruments : Fair values for the Company’s off-balance-sheet lending commitments (guarantees, letters of credit and commitments to extend credit) are based on fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements. The estimated fair values of financial instruments are as follows (in thousands): March 31, 2018 Carrying Amount Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Cash and due from banks $ 332,234 $ 332,234 $ 332,234 $ — $ — Interest earning deposits with banks 50,624 50,624 50,624 — — Investment securities available for sale 1,679,011 1,679,011 — 1,678,663 348 Investment securities held to maturity 933,319 950,806 — 950,806 — Marketable equity securities 11,124 11,124 11,124 — — Non-marketable securities - FHLB and FRB stock 118,955 118,955 — — 118,955 Loans held for sale 561,549 561,549 — 561,549 — Loans, net 13,773,268 13,873,378 — 39,206 13,834,172 Accrued interest receivable 65,445 65,445 65,445 — — Derivative financial instruments 49,005 49,005 1,082 45,642 2,281 Financial Liabilities: Non-interest bearing deposits $ 6,385,149 $ 6,385,149 $ 6,385,149 $ — $ — Interest bearing deposits 8,585,444 8,574,742 — — 8,574,742 Short-term borrowings 717,679 717,400 — — 717,400 Long-term borrowings 851,221 855,337 — — 855,337 Junior subordinated notes issued to capital trusts 194,304 156,323 — — 156,323 Accrued interest payable 8,352 8,352 8,352 — — Derivative financial instruments 46,181 46,181 2,130 44,051 — December 31, 2017 Carrying Amount Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Cash and due from banks $ 397,880 $ 397,880 $ 397,880 $ — $ — Interest earning deposits with banks 181,341 181,341 181,341 — — Investment securities available for sale 1,408,326 1,408,326 11,063 1,396,900 363 Investment securities held to maturity 959,082 992,455 — 992,455 — Non-marketable securities - FHLB and FRB stock 114,111 114,111 — — 114,111 Loans held for sale 548,578 548,578 — 548,578 — Loans, net 13,808,352 13,988,392 — 40,531 13,947,861 Accrued interest receivable 63,589 63,589 63,589 — — Derivative financial instruments 31,499 31,499 389 29,539 1,571 Financial Liabilities: Non-interest bearing deposits $ 6,381,512 $ 6,381,512 $ 6,381,512 $ — $ — Interest bearing deposits 8,576,866 8,569,368 — — 8,569,368 Short-term borrowings 861,039 860,676 — — 860,676 Long-term borrowings 505,158 513,725 — — 513,725 Junior subordinated notes issued to capital trusts 211,494 170,965 — — 170,965 Accrued interest payable 6,458 6,458 6,458 — — Derivative financial instruments 40,296 40,296 1,072 39,224 —

Stock Incentive Plans

Stock Incentive Plans	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Incentive Plans	Stock Incentive Plans ASC Topic 718 requires that the grant date fair value of equity awards to employees be recognized as compensation expense over the period during which an employee is required to provide service in exchange for such award. The following table summarizes the impact of the Company’s share-based payment plans in the financial statements for the periods shown (in thousands): Three Months Ended March 31, 2018 2017 Total compensation expense for share-based payment plans during the period $ 4,451 $ 4,481 Amount of related income tax benefit recognized in income (1) 1,354 4,422 (1) Includes tax benefits recorded for the vesting of restricted shares and exercise of options. The Company adopted the Omnibus Incentive Plan (the “Omnibus Plan”) in 1997. On May 28, 2014, the Company’s stockholders approved the third amendment and restatement of the Omnibus Plan to add 3,100,000 authorized shares for a total of 11,400,000 shares of common stock authorized to be utilized in connection with awards under the Omnibus Plan to directors, officers, and employees of the Company or any of its subsidiaries. The number of shares authorized increased by 2,400,000 to 13,800,000 upon completion of the Taylor Capital merger. Equity grants under the Omnibus Plan can be in the form of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards. Shares awarded in the form of restricted stock, restricted stock units, performance shares, performance units, or other stock-based awards generally will reduce the shares available under the Omnibus Plan on a 2 -for- 1 basis. No more than 10% of the total number of authorized shares may be issued with respect to awards granted after May 28, 2014, other than stock appreciation rights, stock options and performance-based awards, which at the date of grant are scheduled to fully vest prior to three years from the date of grant (although such awards may provide scheduled vesting earlier with respect to some of such shares and for acceleration of vesting as provided in the Omnibus Plan). As of March 31, 2018 , there were 2,099,458 shares available for future grants. Annual equity-based incentive awards are generally granted to selected officers and employees in the first quarter of the year. Options are granted with an exercise price equal to no less than the market price of the Company’s shares at the date of grant; those option awards generally vest over four years of service and have 10 -year contractual terms. Restricted shares and units typically vest over a two to four year period. Equity awards may also be granted at other times throughout the year in connection with the recruitment and retention of officers and employees. Directors currently may elect, in lieu of cash, to receive up to 70% of their fees in stock options with a five year term, which are fully vested on the grant date (provided that the director may not sell the underlying shares for at least six months after the grant date), and up to 100% of their fees in restricted shares, which vest one year after the grant date. The following table summarizes changes in stock options for the three months ended March 31, 2018 : Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value (in thousands) Options outstanding as of December 31, 2017 1,721,978 $ 29.10 5.19 Granted 156,687 41.00 Exercised (95,749 ) 27.24 Expired (1,092 ) 39.28 Forfeited or cancelled (4,764 ) 30.22 Options outstanding as of March 31, 2018 1,777,060 $ 30.24 5.53 $ 19,173 Options exercisable as of March 31, 2018 1,265,177 $ 27.71 4.32 $ 16,468 The fair value of each option award is estimated on the date of grant using the Black-Scholes option pricing model based on certain assumptions. Expected volatility is based on historical volatility and the expectations of future volatility of Company shares. The risk free interest rate for periods within the contractual term of the option is based on the U.S. Treasury yield curve in effect at the time of the grant. The expected life of options is estimated based on historical employee behavior and represents the period of time that options granted are expected to remain outstanding. The following assumptions were used for options granted during the three months ended March 31, 2018 : March 31, 2018 Risk-free interest rate 2.80 % Expected volatility of Company’s stock 25.98 % Expected dividend yield 2.06 % Expected life of options 5.9 years Weighted average fair value per option of options granted during the year $ 9.61 The total intrinsic value of options exercised during the three months ended March 31, 2018 and 2017 was $1.6 million and $2.9 million , respectively. The following is a summary of changes in restricted shares and units for the three months ended March 31, 2018 : Number of Shares and Units Weighted Average Grant Date Fair Value Shares and units outstanding at December 31, 2017 973,201 $ 37.03 Granted 414,012 41.44 Vested (297,033 ) 34.91 Forfeited or cancelled (80,035 ) 34.38 Shares and units outstanding at March 31, 2018 1,010,145 39.67 The total intrinsic value of restricted shares and units that vested during the three months ended March 31, 2018 and 2017 was $12.5 million and $15.3 million , respectively. The Company awarded 71,567 , 65,476 , and 80,780 market-based restricted stock units in 2018, 2017, and 2016, respectively, which entitle recipients to shares of common stock at the end of a three year vesting period. Recipients will earn shares, totaling between 0% and 175% of the number of units issued, based on the Company's total stockholder return relative to a specified peer group of financial institutions over the three year period. The Company awarded 71,560 market-based restricted stock units in 2015 that vested in 2018. The threshold performance for the units granted in 2015 was not met and, as a result, no shares were issued. The market-based restricted stock units are included in the preceding table as if the recipients earned shares equal to 100% of the units issued. A Monte Carlo simulation model was used to value the market-based restricted stock units at the time awarded. As of March 31, 2018 , there was $35.8 million of total unrecognized compensation cost related to nonvested share-based compensation arrangements (including share option and nonvested share awards) granted under the Omnibus Plan. At March 31, 2018 , the weighted-average period over which the unrecognized compensation expense is expected to be recognized was approximately three years.

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company offers various derivatives, including interest rate swaps and foreign currency forward contracts, to its qualifying customers which can mitigate our exposure to market risk through the execution of off-setting positions with inter-bank dealer counterparties. This also permits the Company to offer customized risk management solutions to our customers. These customer accommodations and any offsetting financial contracts are treated as non-designated derivative instruments and carried at fair value through an adjustment to the statement of operations. Interest rate swap and foreign currency forward contracts involve the risk of dealing with counterparties and their ability to meet contractual terms. The net amount payable or receivable under interest rate swaps is accrued as an adjustment to interest income. The net amount payable as of March 31, 2018 and December 31, 2017 was approximately $1 thousand . The Company's credit exposure on interest rate swaps is limited to the Company's net favorable value and interest payments of all swaps to each counterparty. In such cases, collateral is generally required from the counterparties involved if the net value of the swaps exceeds a nominal amount. At March 31, 2018 , the Company’s credit exposure relating to interest rate swaps was approximately $4.8 million , which is secured by the underlying collateral on customer loans. The Company also enters into mortgage banking derivatives which are classified as non-designated hedging derivatives. These derivatives include interest rate lock commitments provided to customers to fund certain mortgage loans to be sold into the secondary market and forward commitments for the future delivery of such loans. It is the Company's practice to enter into forward commitments for the future delivery of residential mortgage loans when interest rate lock commitments are entered into in order to economically hedge the effect of future changes in interest rates on its commitments to fund the loans as well as on its portfolio of mortgage loans held-for-sale. The Company had fair value commercial loan interest rate swaps, to hedge its interest rate risk, with an aggregate notional amount of $45 thousand at March 31, 2018 . For fair value hedges, the changes in fair values of both the hedging derivative and the hedged item were recorded in current earnings as other income. Interest rate swaps, swaptions and treasury futures are used in order to lessen the price volatility of the mortgage servicing rights asset. The Company also uses forward commitments to buy to-be-announced ("TBA") mortgage securities for which the Company does not intend to take delivery of the security and will enter into an offsetting position before physical delivery to lessen the price volatility of the mortgage servicing rights asset. These derivatives are recorded at their fair value on the consolidated balance sheets in other assets with changes in fair value recorded on the consolidated statements of operations in mortgage banking revenue in non-interest income. The Company’s derivative financial instruments are summarized below as of March 31, 2018 and December 31, 2017 (in thousands): Asset Derivatives Liability Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Notional Estimated Notional Estimated Notional Estimated Notional Estimated Amount Fair Value Amount Fair Value Amount Fair Value Amount Fair Value Derivative instruments designated as hedges of fair value: Interest rate swap contracts (1) $ — $ — $ — $ — $ 45 $ (1 ) $ 58 $ (1 ) Stand-alone derivative instruments: (2) Interest rate swap contracts 1,647,481 28,308 1,563,109 21,217 1,647,481 (28,308 ) 1,563,109 (21,217 ) Interest rate options contracts 402,633 3,326 372,927 1,887 402,566 (3,326 ) 372,927 (1,887 ) Foreign exchange contracts 57,689 3,879 40,713 1,934 56,866 (3,695 ) 34,029 (1,759 ) Spot foreign exchange contracts 503 20 1,424 23 117 (12 ) 24 — Mortgage related derivatives: Interest rate swap contracts 275,000 9,234 458,000 4,479 270,000 (8,709 ) 1,008,000 (14,360 ) Interest rate swaptions contracts 290,000 875 — — — — — — Treasury futures contracts 20,000 100 28,000 39 — — 30,000 (222 ) TBA mortgage securities 50,000 406 15,000 16 — — 100,000 (63 ) Forward loan sale commitments 126,000 576 259,000 333 606,500 (2,130 ) 483,500 (787 ) Interest rate lock commitments 499,337 2,281 404,557 1,571 — — — — Total stand-alone derivative instruments 3,368,643 49,005 3,142,730 31,499 2,983,530 (46,180 ) 3,591,589 (40,295 ) Total $ 3,368,643 $ 49,005 $ 3,142,730 $ 31,499 $ 2,983,575 $ (46,181 ) $ 3,591,647 $ (40,296 ) (1) Derivative instruments designated to hedge fixed-rate commercial real estate loans. (2) These portfolio swaps are not designated as hedging instruments under ASC Topic 815. Amounts included in other operating income in the consolidated statements of operations related to derivative financial instruments were as follows (in thousands): Three Months Ended March 31, 2018 2017 Derivative instruments designated as hedges of fair value: Interest rate swap contracts $ — $ 1 Stand-alone derivative instruments: Interest rate swap contracts 1,715 1,849 Interest rate options contracts — — Foreign exchange contracts 43 63 Spot foreign exchange contracts 733 678 Mortgage related derivatives (581 ) (10,141 ) Total stand-alone derivative instruments 1,910 (7,551 ) Total $ 1,910 $ (7,550 ) Methods and assumptions used by the Company in estimating the fair value of its interest rate swaps are discussed in Note 13 to consolidated financial statements. Certain instruments and transactions subject to an agreement similar to a master netting arrangement are eligible for offset in the consolidated balance sheet. The instruments and transactions would include derivatives, sale and repurchase agreements and reverse sale and repurchase agreements, and securities borrowing and securities lending arrangements. The Company’s derivative transactions with financial institution counterparties are generally executed under International Swaps and Derivative Association (“ISDA”) master agreements which include “right of set-off” provisions. Under these agreements, there is generally a legally enforceable right to offset recognized amounts, and there may be an intention to settle such amounts on a net basis. The Company, however, does not generally offset such financial instruments for financial reporting purposes. Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of March 31, 2018 is summarized below (in thousands): Financial Assets Financial Liabilities Gross Amount Recognized Gross Amount Offset Net Amount Recognized Gross Amount Recognized Gross Amount Offset Net Amount Recognized Derivatives: Interest rate swap contracts, caps and floors $ 26,570 $ — $ 26,570 $ 4,976 $ — $ 4,976 Foreign exchange contracts 414 — 414 3,475 — 3,475 Mortgage related derivatives 11,190 — 11,190 10,839 — 10,839 Total derivatives 38,174 — 38,174 19,290 — 19,290 Repurchase agreements — — — 225,962 — 225,962 Total $ 38,174 $ — $ 38,174 $ 245,252 $ — $ 245,252 Financial Assets Financial Liabilities Net Amount Recognized Financial Instruments Collateral Net Amount Net Amount Recognized Financial Instruments Collateral Net Amount Derivatives: Counterparty A $ 13,664 $ (7,524 ) $ — $ 6,140 $ 7,524 $ (7,524 ) $ — $ — Counterparty B 10,301 (585 ) — 9,716 585 (585 ) — — Counterparty C 7,999 (5,616 ) (2,383 ) — 5,616 (5,616 ) — — Other counterparties 6,210 (2,768 ) (2,308 ) 1,134 5,565 (2,768 ) (1,308 ) 1,489 Total derivatives 38,174 (16,493 ) (4,691 ) 16,990 19,290 (16,493 ) (1,308 ) 1,489 Repurchase agreements — — — — 225,962 — (225,962 ) — Total $ 38,174 $ (16,493 ) $ (4,691 ) $ 16,990 $ 245,252 $ (16,493 ) $ (227,270 ) $ 1,489 Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2017 is summarized below (in thousands): Financial Assets Financial Liabilities Gross Amount Recognized Gross Amount Offset Net Amount Recognized Gross Amount Recognized Gross Amount Offset Net Amount Recognized Derivatives: Interest rate swap contracts, caps and floors $ 11,659 $ — $ 11,659 $ 11,562 $ — $ 11,562 Foreign exchange contracts 1,013 — 1,013 953 — 953 Mortgage related derivatives 4,868 — 4,868 15,432 — 15,432 Total derivatives 17,540 — 17,540 27,947 — 27,947 Repurchase agreements — — — 232,789 — 232,789 Total $ 17,540 $ — $ 17,540 $ 260,736 $ — $ 260,736 Financial Assets Financial Liabilities Net Amount Recognized Financial Instruments Collateral Net Amount Net Amount Recognized Financial Instruments Collateral Net Amount Derivatives: Counterparty A $ 6,068 $ (6,068 ) $ — $ — $ 13,807 $ (6,068 ) $ (7,739 ) $ — Counterparty B 3,261 (3,261 ) — — 5,595 (3,261 ) (2,334 ) — Counterparty C 5,285 (3,640 ) — 1,645 3,640 (3,640 ) — — Other counterparties 2,926 (1,750 ) — 1,176 4,905 (1,750 ) (3,150 ) 5 Total derivatives 17,540 (14,719 ) — 2,821 27,947 (14,719 ) (13,223 ) 5 Repurchase agreements — — — — 232,789 — (232,789 ) — Total $ 17,540 $ (14,719 ) $ — $ 2,821 $ 260,736 $ (14,719 ) $ (246,012 ) $ 5

Operating Segments

Operating Segments	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Operating Segments	Operating Segments The Company's operations currently consist of three reportable operating segments: Banking, Leasing, and Mortgage Banking. The Company offers different products and services through its three segments. The accounting policies of the segments are generally the same as those of the consolidated company. The Banking Segment generates its revenues primarily from its lending, deposit gathering and fee business activities. The profitability of this segment's operations depends primarily on its net interest income after provision for credit losses, which is the difference between interest earned on interest earning assets and interest paid on interest bearing liabilities less provision for credit losses. The provision for credit losses is almost entirely dependent on changes in the Banking Segment's loan portfolio and management’s assessment of the collectability of the loan portfolio as well as prevailing economic and market conditions. The Banking Segment is also subject to an extensive system of laws and regulations that are intended primarily for the protection of depositors and other customers, federal deposit insurance funds and the banking system as a whole. These laws and regulations govern such areas as capital, permissible activities, allowance for loan and lease losses, loans and investments, and rates of interest that can be charged on loans. The Leasing Segment generates its revenues through lease originations and related services. The Leasing Segment invests directly in equipment that the Company leases (referred to as direct finance, leveraged or operating leases) to "Fortune 1000," middle-market companies and health care providers located throughout the United States. The lease portfolio is made up of various kinds of equipment, generally technology related, such as computer systems, satellite equipment, medical equipment and general manufacturing, industrial, construction and transportation equipment. The Leasing Segment also specializes in selling third party equipment maintenance contracts to large companies. The Mortgage Banking Segment originates residential mortgage loans for sale to investors and for the Company's portfolio through its retail and third party originator channels. This segment also services residential mortgage loans for various investors and for loans owned by the Company. The Mortgage Banking Segment is subject to an extensive system of laws and regulations that are intended primarily for the protection of customers. On April 12, 2018, the Company announced the discontinuation of its national mortgage origination business, which includes substantially all originations outside of the Company's consumer banking footprint in the Chicagoland area. The Company expects to stop operating its mortgage business as a defined segment with separate Mortgage Banking Segment reporting prior to the fourth quarter of 2018. See "Note 17. Subsequent Event." Net interest income for the Leasing and Mortgage Banking segments include adjustments based on the Company's internal funds transfer pricing model. Non-interest income for the Leasing Segment includes income on loans originated for the sole purpose of funding equipment purchases related to leases at the Company's lease subsidiaries. The following tables present summary financial information for the reportable segments (in thousands): Banking Leasing Mortgage Banking Consolidated Three months ended March 31, 2018 Net interest income $ 140,471 $ 2,482 $ 10,428 $ 153,381 Provision for credit losses 7,579 (24 ) (47 ) 7,508 Non-interest income 43,092 24,856 24,854 92,802 Non-interest expense (1) 115,826 15,496 36,564 167,886 Income tax expense 13,608 756 (332 ) 14,032 Net income $ 46,550 $ 11,110 $ (903 ) $ 56,757 Total assets $ 16,582,585 $ 1,360,117 $ 2,224,821 $ 20,167,523 Three months ended March 31, 2017 Net interest income $ 131,449 $ 2,269 $ 9,325 $ 143,043 Provision for credit losses 3,527 (135 ) 342 3,734 Non-interest income 43,208 21,463 27,779 92,450 Non-interest expense (1) 108,516 13,844 33,982 156,342 Income tax expense 15,660 4,119 1,101 20,880 Net income $ 46,954 $ 5,904 $ 1,679 $ 54,537 Total assets $ 16,009,339 $ 1,173,558 $ 1,963,165 $ 19,146,062 (1) Includes merger related and repositioning expenses of $644 thousand and $258 thousand in the Banking Segment for the three months ended March 31, 2018 and 2017 , respectively.

Preferred Stock

Preferred Stock	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Preferred Stock	Preferred Stock On August 18, 2014, in connection with the Taylor Capital merger, the Company issued one share of its Perpetual Non-Cumulative Preferred Stock, Series A (“Company Series A Preferred Stock”), in exchange for each of the 4,000,000 outstanding shares of Taylor Capital’s Perpetual Non-Cumulative Preferred Stock, Series A. Holders of the Company Series A Preferred Stock were entitled to receive, when as and if declared by the Company’s board of directors, non-cumulative cash dividends on the liquidation preference amount, which was $25 per share, at a rate of 8.00% per annum, payable quarterly. The Company Series A Preferred Stock was included in Tier 1 capital for regulatory capital purposes. On February 15, 2018, the Company redeemed all of the 4,000,000 issued and outstanding shares of Company Series A Preferred Stock at a redemption price of $25.00 per share, or $100.0 million in the aggregate. The excess carrying amount of the Series A Preferred Stock in the amount of $15.3 million was retained in stockholders' equity and reflected as income available to common stockholders, which was included in the calculation of earnings per common share. On November 22, 2017, the Company issued 8,000,000 depositary shares, each representing a 1/40th interest in a share of its Non-Cumulative Preferred Stock, Series C (“Company Series C Preferred Stock”). Holders of the Company Series C Preferred Stock are entitled to receive, when as and if declared by the Company's board of directors, non-cumulative cash dividends on the liquidation preference, which is $25 per depositary share (equivalent to $1,000 per share of preferred stock), at a rate of 6.00% per annum, payable quarterly. The Company Series C Preferred Stock is included in Tier 1 capital for regulatory capital purposes and is redeemable at the option of the Company at a redemption price of $25 per depositary share, plus any declared and unpaid dividends, (i) in whole or in part from time to time, on any dividend payment date on or after November 25, 2022, and (ii) in whole but not in part prior to November 25, 2022, within 90 days following a “regulatory capital treatment event,” as defined in the terms of the Company Series C Preferred Stock. The Company must receive the approval of the Federal Reserve Board prior to any redemption of the Company Series C Preferred Stock.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On April 12, 2018, the Company announced the discontinuation of its national mortgage origination business, which includes substantially all originations outside of the Company's consumer banking footprint in the Chicagoland area. As a result, the Company expects to incur one-time pre-tax costs of approximately $37 to $41 million during the remainder of 2018 and to stop operating its mortgage business as a defined segment with separate Mortgage Banking Segment reporting prior to the fourth quarter of 2018. This discontinuation is not expected to be reported as discontinued operations. The Company also expects to record a goodwill impairment loss in the amount of $3.6 million in the second quarter of 2018. The Company plans to continue originating residential mortgage loans in the greater Chicago area through its mortgage retail offices, retain the mortgage servicing asset as well as its mortgage servicing operation in Wilmington, Ohio, and continue holding residential mortgages on its balance sheet.

New Authoritative Accounting 26

New Authoritative Accounting Guidance (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
New Authoritative Accounting Guidance	ASC Topic 805 "Business Combinations." New authoritative accounting guidance under ASC Topic 805 "Business Combinations" amends prior guidance to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 606 "Revenue from Contracts with Customers." New authoritative accounting guidance under ASC Topic 606, "Revenue from Contracts with Customers" amended prior guidance to require 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. The new authoritative guidance was initially effective for reporting periods after January 1, 2017 but was deferred to January 1, 2018. The Company's revenue is comprised of interest income on financial assets, which is excluded from the scope of this new guidance, and non-interest income. This new guidance changes how certain recurring revenue streams are recognized within lease financing revenue and insignificant components of non-interest income. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. See "Accounting changes" below. ASC Topic 825 "Financial Instruments." New authoritative accounting guidance under ASC Topic 825 "Financial Instruments" amended prior guidance to require equity investments (except those accounted for under the equity method of accounting) to be measured at fair value with changes in fair value recognized in net income. An entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer. The new guidance simplifies the impairment assessment of equity investments without readily determinable fair values, requires public entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from changes in the instrument-specific credit risk when the entity has selected the fair value option for financial instruments and requires separate presentation of financial assets and liabilities by measurement category and form of financial asset. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. See "Accounting changes" below. ASC Topic 405 "Liabilities-Extinguishment of Liabilities." New authoritative accounting guidance under ASC Topic 405, "Liabilities-Extinguishment of Liabilities" amended prior guidance to clarify that liabilities related to the sale of prepaid store-value products within the scope of this guidance are financial liabilities and that breakage for those liabilities are to be accounted for consistent with the breakage guidance in ASC Topic 606 "Revenue from Contracts with Customers." The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 842 "Leases." New authoritative accounting guidance under ASC Topic 842 "Leases" amended prior guidance to require lessees to recognize the assets and liabilities arising from all leases on the balance sheet. The new authoritative guidance defines a lease as a contract, or part of a contract, that conveys the right to control the use of identified property, plant, or equipment (an identified asset) for a period of time in exchange for consideration. In addition, the qualifications for a sale and leaseback transaction have been amended. The new authoritative guidance also requires qualitative and quantitative disclosures by lessees and lessors to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The new authoritative guidance will be effective for reporting periods after January 1, 2019. The Financial Accounting Standards Board issued a proposal in January 2018 to provide an additional transition method that would allow entities to not apply this new guidance in the comparative periods presented in the financial statements and instead recognize a cumulative effect adjustment to the beginning retained earnings at the date of application. The Company is evaluating the new guidance and its impact on the Company's statements of operations and financial condition. The Company expects an increase in assets and liabilities as a result of recording additional lease contracts where the Company is lessee. ASC Topic 815 "Derivatives and Hedging." New authoritative accounting guidance under ASC Topic 815 "Derivatives and Hedging" amended prior guidance to better align an entity's risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The new authoritative guidance expands and refines hedge accounting for both nonfinancial and financial risk components. The new authoritative guidance will be effective for reporting periods after January 1, 2019 with early adoption permitted. This new authoritative guidance is not expected to have a significant impact on the Company's statements of operations or financial condition. ASC Topic 718 "Compensation - Stock Compensation." New authoritative accounting guidance under ASC Topic 718 "Compensation - Stock Compensation" amends prior guidance by clarifying which changes to terms or conditions of a share-based payment award require an entity to apply modification accounting. An entity should account for the effects of a modification unless the fair value, vesting conditions and classification of the modified award are the same as the original award. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 326 "Financial Instruments - Credit Losses." New authoritative accounting guidance under ASC Topic 326 " Financial Instruments - Credit Losses " amended the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information for credit loss estimates. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The new authoritative guidance also requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected (net of the allowance for credit losses). In addition, the credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses rather than a write-down. The new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company is evaluating the new guidance and expects it to have an impact on the Company's statements of operations and financial condition, the significance of which is not yet known nor can it be reasonably estimated currently. Due to the significant differences in the new authoritative guidance from existing GAAP, the implementation of this guidance may result in material changes in our accounting for credit losses on the financial instruments and will be impacted by the Company's loan and securities portfolios' composition, attributes, and quality in addition to the prevailing economic conditions and forecasts at the time of adoption. As part of the Company's evaluation process, it has established a steering committee and working group, including individuals from various functional areas, to assess processes and related controls, portfolio segmentation, model development, system requirements, and needed resources. The Company is also considering third-party consultants to assist in the evaluation process. ASC Topic 230 "Statement of Cash Flows." New authoritative accounting guidance under ASC Topic 230 "Statement of Cash Flows" addresses eight specific cash flow classification issues with the objective of reducing the existing diversity in practice. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. New authoritative accounting guidance under ASC Topic 230 "Statement of Cash Flows" amends prior guidance to require an entity to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling the beginning of period and end of period total amounts shown on the statement of cash flows. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 740 "Income Taxes." New authoritative accounting guidance under ASC Topic 740 "Income Taxes" amends prior guidance to require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 350 "Intangibles-Goodwill and Other." New authoritative accounting guidance under ASC Topic 350 "Intangibles-Goodwill and Other" amends prior guidance to eliminate Step 2 from the goodwill impairment test and require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new authoritative guidance will be effective for reporting periods after January 1, 2020. The Company is evaluating the new guidance and its impact on the Company's statements of operations and financial condition. ASC Topic 610 "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets." New authoritative accounting guidance under ASC Topic 610 "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets" amends prior guidance to clarify the scope of Subtopic 610-20 by defining in substance nonfinancial assets and to add guidance for partial sales of nonfinancial assets. The Company adopted this new authoritative guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. ASC Topic 310 "Receivables - Nonrefundable Fees and Other Costs." New authoritative accounting guidance under ASC Topic 310 "Receivables - Nonrefundable Fees and Other Costs" amends prior guidance by shortening the amortization period for certain callable debt securities held at a premium requiring the premium to be amortized to the earliest call date. The new authoritative guidance will be effective for reporting periods after January 1, 2019 with early adoption permitted. The Company is evaluating the new guidance and its impact on the Company's statements of operations and financial condition. ASC Topic 220 "Income Statement - Reporting Comprehensive Income." New authoritative accounting guidance under ASC Topic 220 "Income Statement - Reporting Comprehensive Income" allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from enactment of H.R. 1, originally known as the "Tax Cuts and Jobs Act." The new authoritative guidance will be effective for reporting periods after January 1, 2019 with early adoption permitted. The Company early adopted the new guidance on January 1, 2018, and it did not have a significant impact on the Company's statements of operations or financial condition. See "Accounting changes" below. Accounting changes . The Company adopted the new authoritative accounting guidance under ASC Topic 606, "Revenue from Contracts with Customers" on January 1, 2018 using the modified retrospective transition method for contracts that were not completed at the date of initial application. The Company recognized a cumulative effect reduction to the beginning retained earnings totaling $683 thousand . This amount relates to lease financing revenue where the Company's performance obligation is over time. Previously, such revenue was recognized immediately. See " Lease financing revenue, net " below . The new authoritative accounting guidance under ASC Topic 606 requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. To achieve this, the Company takes the following steps: identify the contract(s) with a customer; identify the performance obligations in the contract; determine the transaction price; allocate the transaction price to the performance obligations in the contract; and recognize revenue when (or as) the Company satisfies a performance obligation. The non-interest revenue streams that are considered to be in the scope of this new guidance are discussed below. Lease financing revenue, net. Fees from the sale of third-party equipment maintenance contracts are included within lease financing revenue, net. The Company sells third-party equipment maintenance contracts and provides customers with an asset and maintenance contract management tool over the life of the maintenance contract. Since the Company provides support for the asset and maintenance contract management tool, the Company's performance obligation is satisfied over the life of the maintenance contract, and the fees are recognized monthly over the life of the maintenance contract. Payment is typically received at the time of sale of the maintenance contract. Treasury management fees and consumer and other deposit service fees. Deposit related fees (account analysis fees, monthly service fees, and other related fees) are included within treasury management fees and consumer and other deposit service fees. The Company's performance obligation is ongoing and either party may cancel at any time. These fees are generally recognized as the services are rendered on a monthly basis. Payment is typically received monthly. Wealth management fees. Wealth management fees include revenue from the management and advisement of client assets and trust administration. The Company's performance obligation is generally satisfied over time, and the fees are recognized monthly. Payment is typically received quarterly or annually. Card fees. Card fees include debit and credit card interchange fees and ATM fees. For debit and credit card transactions, the Company considers the merchant as the customer for interchange revenue with the performance obligation being satisfied when the cardholder purchases goods or services from the merchant. Interchange revenue is recognized as the services are provided. The Company's performance obligation for ATM fees is satisfied when services are provided, and the fees are recognized at that time. Payment is typically received immediately or in the following month. Capital markets and international banking fees. Capital markets and international banking fees include M&A advisory and syndication fees. The Company's performance obligation is generally satisfied over time, and the fees are recognized monthly. For M&A advisory fees, a portion of the payment is received at the beginning of the engagement with the remainder once the transaction is completed. For syndication fees, payment is received annually. The Company also adopted the new authoritative accounting guidance under ASC Topic 825 "Financial Instruments" and ASC Topic 220 "Income Statement - Reporting Comprehensive Income" on January 1, 2018. The Company recognized a cumulative effect increase to the beginning retained earnings and accumulated other comprehensive income totaling $385 thousand under ASC Topic 825 representing the fair value adjustment to equity securities at the date of initial application. In addition, the Company reclassified $1.2 million from accumulated other comprehensive loss to retained earnings for the stranded tax effects resulting from enactment of the Tax Cuts and Jobs Act at the date of initial application of the new guidance under ASC Topic 220.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Reconciliation of the Number of Shares Used in the Calculation of Basic and Diluted Earnings Per Common Share	The following table presents a reconciliation of the number of shares used in the calculation of basic and diluted earnings per common share (amounts in thousands, except share and per share data). Three Months Ended March 31, 2018 2017 Distributed earnings allocated to common stock $ 20,283 $ 16,131 Undistributed earnings 36,474 38,406 Net income 56,757 54,537 Less: preferred stock dividends 3,100 2,003 Plus: return from preferred stockholders due to redemption (1) 15,280 — Net income available to common stockholders for basic earnings per common share 68,937 52,534 Plus: preferred stock dividends on convertible preferred stock — 3 Less: earnings allocated to participating securities 2 1 Earnings allocated to common stockholders for diluted earnings per common share $ 68,935 $ 52,536 Weighted average shares outstanding for basic earnings per common share 84,065,681 83,662,430 Dilutive effect of: Stock options 507,786 636,515 Restricted shares and units 322,934 471,863 Convertible preferred stock — 7,322 Total dilutive effect of equity awards and convertible preferred stock 830,720 1,115,700 Weighted average shares outstanding for diluted earnings per common share 84,896,401 84,778,130 Basic earnings per common share $ 0.82 $ 0.63 Diluted earnings per common share 0.81 0.62 (1) Represents the excess carrying amount over the redemption price of the 8% Series A non-cumulative perpetual preferred stock redeemed in the first quarter of 2018.

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Amortized Cost and Fair Value of Investment Securities	Amortized cost and fair value of investment securities, excluding marketable equity securities and non-marketable FHLB and FRB stock, were as follows as of the dates indicated (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value March 31, 2018 Available for Sale U.S. Government sponsored agencies and enterprises $ 22,948 $ — $ (63 ) $ 22,885 States and political subdivisions 355,058 12,478 (630 ) 366,906 Residential mortgage-backed securities 1,202,251 2,331 (17,514 ) 1,187,068 Commercial mortgage-backed securities 64,144 227 (210 ) 64,161 Corporate bonds 38,020 1 (30 ) 37,991 Total Available for Sale 1,682,421 15,037 (18,447 ) 1,679,011 Held to Maturity States and political subdivisions 874,306 18,704 (1,910 ) 891,100 Residential mortgage-backed securities 59,013 693 — 59,706 Total Held to Maturity 933,319 19,397 (1,910 ) 950,806 Total $ 2,615,740 $ 34,434 $ (20,357 ) $ 2,629,817 December 31, 2017 Available for Sale U.S. Government sponsored agencies and enterprises $ 23,013 $ 3 $ (9 ) $ 23,007 States and political subdivisions 363,813 15,998 (486 ) 379,325 Residential mortgage-backed securities 861,594 3,035 (11,930 ) 852,699 Commercial mortgage-backed securities 71,554 612 (131 ) 72,035 Corporate bonds 70,155 84 (42 ) 70,197 Equity securities (1) 11,236 — (173 ) 11,063 Total Available for Sale 1,401,365 19,732 (12,771 ) 1,408,326 Held to Maturity States and political subdivisions 878,400 32,559 (447 ) 910,512 Residential mortgage-backed securities 80,682 1,261 — 81,943 Total Held to Maturity 959,082 33,820 (447 ) 992,455 Total $ 2,360,447 $ 53,552 $ (13,218 ) $ 2,400,781 (1) Reflected in marketable equity securities on the consolidated balance sheet following the adoption of the new guidance under ASC Topic 825 "Financial Instruments" on January 1, 2018.
Unrealized Losses on Investment Securities and the Fair Value of the Related Securities	Unrealized losses on investment securities by length of time in a continuous unrealized loss position and the fair value of the related securities at March 31, 2018 were as follows (in thousands): Less Than 12 Months 12 Months or More Total Fair Unrealized Fair Unrealized Fair Unrealized Value Losses Value Losses Value Losses Available for Sale U.S. Government sponsored agencies and enterprises $ 22,885 $ (63 ) $ — $ — $ 22,885 $ (63 ) States and political subdivisions 18,110 (69 ) 18,586 (561 ) 36,696 (630 ) Residential mortgage-backed securities 442,766 (4,035 ) 390,083 (13,479 ) 832,849 (17,514 ) Commercial mortgage-backed securities 32,416 (136 ) 11,322 (74 ) 43,738 (210 ) Corporate bonds 19,044 (12 ) 9,980 (18 ) 29,024 (30 ) Total Available for Sale 535,221 (4,315 ) 429,971 (14,132 ) 965,192 (18,447 ) Held to Maturity States and political subdivisions 158,964 (1,455 ) 11,631 (455 ) 170,595 (1,910 ) Total $ 694,185 $ (5,770 ) $ 441,602 $ (14,587 ) $ 1,135,787 $ (20,357 ) Unrealized losses on investment securities by length of time in a continuous unrealized loss position and the fair value of the related securities at December 31, 2017 were as follows (in thousands): Less Than 12 Months 12 Months or More Total Fair Unrealized Fair Unrealized Fair Unrealized Value Losses Value Losses Value Losses Available for Sale U.S. Government sponsored agencies and enterprises $ 5,111 $ (9 ) $ — $ — $ 5,111 $ (9 ) States and political subdivisions 9,016 (29 ) 18,754 (457 ) 27,770 (486 ) Residential mortgage-backed securities 256,769 (1,853 ) 407,224 (10,077 ) 663,993 (11,930 ) Commercial mortgage-backed securities 19,483 (20 ) 14,583 (111 ) 34,066 (131 ) Corporate bonds 7,052 (8 ) 9,963 (34 ) 17,015 (42 ) Equity securities 11,063 (173 ) — — 11,063 (173 ) Total Available for Sale 308,494 (2,092 ) 450,524 (10,679 ) 759,018 (12,771 ) Held to Maturity States and political subdivisions 45,499 (257 ) 12,561 (190 ) 58,060 (447 ) Total $ 353,993 $ (2,349 ) $ 463,085 $ (10,869 ) $ 817,078 $ (13,218 )
Summary of Net Gains (Losses) on Investment Securities Available for Sale	Net gains (losses) recognized on investment securities were as follows (in thousands): Three Months Ended March 31, 2018 2017 Realized gains $ 88 $ 237 Realized losses (262 ) (6 ) Net (losses) gains $ (174 ) $ 231
Amortized Cost and Fair Value of Investment Securities by Contractual Maturity	The amortized cost and fair value of investment securities as of March 31, 2018 by contractual maturity are shown below. Maturities may differ from contractual maturities in mortgage-backed securities because the mortgages underlying the securities may be called or repaid without any penalties. Therefore, mortgage-backed securities are not included in the maturity categories in the following maturity summary. Amortized Fair (In thousands) Cost Value Available for sale: Due in one year or less $ 87,751 $ 87,946 Due after one year through five years 142,875 147,296 Due after five years through ten years 38,869 39,263 Due after ten years 146,531 153,277 Residential and commercial mortgage-backed securities 1,266,395 1,251,229 1,682,421 1,679,011 Held to maturity: Due in one year or less 45,415 45,629 Due after one year through five years 176,545 182,455 Due after five years through ten years 207,875 213,927 Due after ten years 444,471 449,089 Residential mortgage-backed securities 59,013 59,706 933,319 950,806 Total $ 2,615,740 $ 2,629,817

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Schedule of Composition of Loans	Loans consist of the following at (in thousands): March 31, December 31, Commercial loans $ 4,790,803 $ 4,786,180 Commercial loans collateralized by assignment of lease payments 2,095,189 2,113,135 Commercial real estate 4,093,045 4,147,529 Residential real estate 1,391,900 1,432,458 Construction real estate 479,638 406,849 Indirect vehicle 692,642 667,928 Home equity 202,920 219,098 Other consumer loans 78,853 73,141 Total loans, excluding purchased credit-impaired loans 13,824,990 13,846,318 Purchased credit-impaired loans 109,990 119,744 Total loans $ 13,934,980 $ 13,966,062
Contractual Aging of the Recorded Investment in Past Due Loans by Class of Loans	The following table presents the contractual aging of the recorded investment in past due loans by class of loans as of March 31, 2018 and December 31, 2017 (in thousands): Current 30-59 Days 60-89 Days Loans Past Due Total Total March 31, 2018 Commercial $ 4,751,376 $ 30,468 $ 1,195 $ 7,764 $ 39,427 $ 4,790,803 Commercial collateralized by assignment of lease payments 2,066,953 22,462 5,073 701 28,236 2,095,189 Commercial real estate: Health care 757,936 — — — — 757,936 Industrial 867,979 2,718 — — 2,718 870,697 Multifamily 580,484 — — 164 164 580,648 Retail 482,646 835 — 229 1,064 483,710 Office 454,793 3,087 — 112 3,199 457,992 Other 937,356 3,704 80 922 4,706 942,062 Residential real estate 1,373,261 9,877 219 8,543 18,639 1,391,900 Construction real estate 479,066 572 — — 572 479,638 Indirect vehicle 687,508 3,646 1,026 462 5,134 692,642 Home equity 197,141 1,397 1,077 3,305 5,779 202,920 Other consumer 78,615 112 71 55 238 78,853 Total loans, excluding purchased credit-impaired loans 13,715,114 78,878 8,741 22,257 109,876 13,824,990 Purchased credit-impaired loans 63,071 10,559 2,685 33,675 46,919 109,990 Total loans $ 13,778,185 $ 89,437 $ 11,426 $ 55,932 $ 156,795 $ 13,934,980 Non-performing loan aging $ 30,610 $ 6,296 $ 2,157 $ 22,257 $ 30,710 $ 61,320 December 31, 2017 Commercial $ 4,769,244 $ 1,702 $ 6,926 $ 8,308 $ 16,936 $ 4,786,180 Commercial collateralized by assignment of lease payments 2,099,246 11,320 1,878 691 13,889 2,113,135 Commercial real estate: Health care 710,722 — — — — 710,722 Industrial 908,394 — — 755 755 909,149 Multifamily 601,844 688 — 732 1,420 603,264 Retail 503,224 — — 474 474 503,698 Office 453,960 — 956 1,454 2,410 456,370 Other 956,181 7,035 76 1,034 8,145 964,326 Residential real estate 1,410,473 12,359 1,907 7,719 21,985 1,432,458 Construction real estate 404,595 2,254 — — 2,254 406,849 Indirect vehicle 661,028 4,905 1,083 912 6,900 667,928 Home equity 210,831 3,161 1,073 4,033 8,267 219,098 Other consumer 72,846 202 36 57 295 73,141 Total loans, excluding purchased credit-impaired loans 13,762,588 43,626 13,935 26,169 83,730 13,846,318 Purchased credit-impaired loans 63,937 8,749 3,997 43,061 55,807 119,744 Total loans $ 13,826,525 $ 52,375 $ 17,932 $ 69,230 $ 139,537 $ 13,966,062 Non-performing loan aging $ 36,879 $ 8,799 $ 4,961 $ 26,169 $ 39,929 $ 76,808
Recorded Investment in Non-accrual Loans and Loans Past Due Ninety Days or More and Still Accruing by Class of Loans	The following table presents the recorded investment in non-accrual loans and loans past due ninety days or more and still accruing by class of loans, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Loans past due Loans past due Non-accrual 90 days or more and still accruing Non-accrual 90 days or more and still accruing Commercial $ 12,654 $ 150 $ 14,001 $ 3,500 Commercial collateralized by assignment of lease payments 672 367 490 531 Commercial real estate: Health care 5,394 — — — Industrial 3,433 — 8,807 — Multifamily 277 — 860 — Office 458 — 2,772 — Retail 286 — 590 — Other 1,129 9 8,016 190 Residential real estate 19,353 362 18,374 1,210 Construction real estate — — — — Indirect vehicle 3,149 5 3,019 81 Home equity 13,338 225 14,305 — Other consumer 8 51 4 58 Total $ 60,151 $ 1,169 $ 71,238 $ 5,570
Risk Category of Loans by Class of Loans	The following tables present the risk category of loans by class of loans based on the most recent analysis performed, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): Pass Special Substandard Doubtful Total March 31, 2018 Commercial $ 4,503,362 $ 164,489 $ 122,952 $ — $ 4,790,803 Commercial collateralized by assignment of lease payments 2,075,740 13,828 5,621 — 2,095,189 Commercial real estate: Health care 684,542 13,156 60,238 — 757,936 Industrial 851,429 11,627 7,641 — 870,697 Multifamily 578,352 858 1,438 — 580,648 Retail 472,397 9,109 2,204 — 483,710 Office 452,559 4,975 458 — 457,992 Other 872,138 37,948 31,976 — 942,062 Construction real estate 479,638 — — — 479,638 Total $ 10,970,157 $ 255,990 $ 232,528 $ — $ 11,458,675 December 31, 2017 Commercial $ 4,535,111 $ 147,232 $ 103,837 $ — $ 4,786,180 Commercial collateralized by assignment of lease payments 2,095,668 7,527 9,940 — 2,113,135 Commercial real estate: Health care 640,751 33,672 36,299 — 710,722 Industrial 885,524 12,411 11,214 — 909,149 Multifamily 595,818 146 7,300 — 603,264 Retail 492,830 8,326 2,542 — 503,698 Office 452,902 696 2,772 — 456,370 Other 891,703 37,682 34,941 — 964,326 Construction real estate 406,849 — — — 406,849 Total $ 10,997,156 $ 247,692 $ 208,845 $ — $ 11,453,693
Recorded Investment in Loan Classes Based on Payment Activity	The following table presents the recorded investment in those loan classes based on payment activity, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): Performing Non-performing Total March 31, 2018 Residential real estate $ 1,372,185 $ 19,715 $ 1,391,900 Indirect vehicle 689,488 3,154 692,642 Home equity 189,357 13,563 202,920 Other consumer 78,794 59 78,853 Total $ 2,329,824 $ 36,491 $ 2,366,315 December 31, 2017 Residential real estate $ 1,412,874 $ 19,584 $ 1,432,458 Indirect vehicle 664,828 3,100 667,928 Home equity 204,793 14,305 219,098 Other consumer 73,079 62 73,141 Total $ 2,355,574 $ 37,051 $ 2,392,625
Loans Individually Evaluated for Impairment by Class of Loans	The following tables present loans individually evaluated for impairment by class of loans, excluding purchased credit-impaired loans, as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 Three Months Ended Unpaid Recorded Partial Allowance for Average Interest With no related allowance recorded: Commercial $ 6,055 $ 5,513 $ 542 $ — $ 7,067 $ — Commercial collateralized by assignment of lease payments — — — — — — Commercial real estate: Health care — — — — — — Industrial — — — — — — Multifamily — — — — — — Retail — — — — — — Office — — — — — — Other 3,309 3,309 — — 3,325 52 Residential real estate 3,432 3,394 38 — 3,394 — Construction real estate — — — — — — Indirect vehicle 424 209 215 — 479 7 Home equity — — — — — — Other consumer — — — — — — With an allowance recorded: Commercial 7,020 7,020 — 2,815 4,925 19 Commercial collateralized by assignment of lease payments — — — — — — Commercial real estate: Health care 5,394 5,394 — 2,979 1,083 28 Industrial 3,433 3,433 — 1,497 2,917 4 Multifamily — — — — — — Retail — — — — — — Office — — — — — — Other — — — — — — Residential real estate 21,766 19,313 2,453 1,996 19,311 1 Construction real estate — — — — — — Indirect vehicle — — — — — — Home equity 32,136 29,661 2,475 1,937 29,681 10 Other consumer — — — — — — Total $ 82,969 $ 77,246 $ 5,723 $ 11,224 $ 72,182 $ 121 December 31, 2017 Year Ended Unpaid Recorded Partial Allowance for Average Interest With no related allowance recorded: Commercial $ 8,312 $ 7,771 $ 541 $ — $ 5,595 $ 95 Commercial collateralized by assignment of lease payments — — — — 301 — Commercial real estate: Health care — — — — — — Industrial — — — — 1,260 8 Multifamily — — — — 1,261 29 Retail — — — — 814 27 Office 527 527 — — 1,426 18 Other 10,597 10,597 — — 2,312 128 Residential real estate 1,950 1,912 38 — 483 — Construction real estate — — — — — — Indirect vehicle 408 202 206 — 411 26 Home equity 81 81 — — 376 — Other consumer — — — — — — With an allowance recorded: Commercial 7,418 7,418 — 2,315 7,668 277 Commercial collateralized by assignment of lease payments — — — — 126 14 Commercial real estate: Health care — — — — — — Industrial 8,339 8,317 22 2,669 3,215 171 Multifamily 568 568 — 320 426 — Retail — — — — 1,345 28 Office 2,293 2,277 16 752 636 4 Other — — — — 29 — Residential real estate 21,380 19,014 2,366 2,158 17,616 25 Construction real estate — — — — — — Indirect vehicle — — — — — — Home equity 30,762 28,286 2,476 2,200 27,982 54 Other consumer — — — — — — Total $ 92,635 $ 86,970 $ 5,665 $ 10,414 $ 73,282 $ 904
Schedule of Loans That Have Been Restructured	The following table presents loans that were restructured during the three months ended March 31, 2018 (dollars in thousands): March 31, 2018 Number of Pre-Modification Recorded Post-Modification Recorded Charge-offs and Performing: Residential real estate 1 $ 88 $ 88 $ 9 Total 1 $ 88 $ 88 $ 9 Non-Performing: Residential real estate 8 $ 1,506 $ 1,506 $ 786 Indirect vehicle 11 67 67 2 Home equity 3 134 134 9 Total 22 $ 1,707 $ 1,707 $ 797 The following table presents loans that were restructured during the three months ended March 31, 2017 (dollars in thousands): March 31, 2017 Number of Pre-Modification Recorded Post-Modification Recorded Charge-offs and Performing: Residential real estate 3 $ 409 $ 409 $ 49 Home equity 1 33 33 3 Total 4 $ 442 $ 442 $ 52 Non-Performing: Residential real estate 9 $ 1,257 $ 1,257 $ 154 Indirect vehicle 3 20 20 4 Total 12 $ 1,277 $ 1,277 $ 158
Troubled Debt Restructuring Activity Rollforward	The following table presents the troubled debt restructurings activity during the three months ended March 31, 2018 (in thousands): Performing Non-performing Beginning balance $ 28,554 $ 30,836 Additions 88 1,707 Charge-offs — (20 ) Principal payments, net (1,471 ) (1,660 ) Removals (77 ) (852 ) Transfer to other real estate owned — — Transfers in 1,962 465 Transfers out (465 ) (1,962 ) Ending balance $ 28,591 $ 28,514
Type of Financing Receivable Modifications and Restructuring	The following table presents the type of modification for loans that have been restructured during the three months ended March 31, 2018 (in thousands): March 31, 2018 Extended Maturity, Delay in Amortization Extended Payments and/or and Reduction Maturity and/or Reduction of of Interest Rate Amortization Interest Rate Total Residential real estate $ 1,256 $ 252 $ 86 $ 1,594 Indirect vehicle — — 67 67 Home equity — 134 — 134 Total $ 1,256 $ 386 $ 153 $ 1,795
Allowance Activity for Credit Losses, Balance in Allowance for Credit Losses and Recorded Investment in Loans by Portfolio Segment	The following table presents the activity in the allowance for credit losses, balance in allowance for credit losses and recorded investment in loans by portfolio segment and based on impairment method as of March 31, 2018 and 2017 (in thousands): Commercial Commercial collateralized by assignment of lease payments Commercial real estate Residential real estate Construction real estate Indirect vehicle Home equity Other consumer Unfunded commitments Total March 31, 2018 Allowance for credit losses: Three Months Ended Beginning balance $ 46,267 $ 13,007 $ 63,429 $ 7,012 $ 15,501 $ 4,728 $ 5,296 $ 2,470 $ 1,698 $ 159,408 Charge-offs 1,402 — 2,476 701 — 1,824 64 351 — 6,818 Recoveries 337 251 762 70 393 1,179 70 230 — 3,292 Provision 349 (265 ) 4,083 (5 ) 3,909 267 (956 ) 146 (20 ) 7,508 Ending balance $ 45,551 $ 12,993 $ 65,798 $ 6,376 $ 19,803 $ 4,350 $ 4,346 $ 2,495 $ 1,678 $ 163,390 Ending allowance balance attributable to loans: Individually evaluated for impairment $ 2,815 $ — $ 4,476 $ 1,996 $ — $ — $ 1,937 $ — $ 563 $ 11,787 Collectively evaluated for impairment 42,662 12,993 60,497 4,380 19,768 4,350 2,409 2,495 1,115 150,669 Acquired and accounted for under ASC 310-30 (1) 74 — 825 — 35 — — — — 934 Total ending allowance balance $ 45,551 $ 12,993 $ 65,798 $ 6,376 $ 19,803 $ 4,350 $ 4,346 $ 2,495 $ 1,678 $ 163,390 Loans: Individually evaluated for impairment $ 12,533 $ — $ 12,136 $ 22,707 $ — $ 209 $ 29,661 $ — $ — $ 77,246 Collectively evaluated for impairment 4,778,270 2,095,189 4,080,909 1,369,193 479,638 692,433 173,259 78,853 — 13,747,744 Acquired and accounted for under ASC 310-30 (1) 10,877 — 24,648 57,633 4,980 — 10,483 1,369 — 109,990 Total ending loans balance $ 4,801,680 $ 2,095,189 $ 4,117,693 $ 1,449,533 $ 484,618 $ 692,642 $ 213,403 $ 80,222 $ — $ 13,934,980 March 31, 2017 Allowance for credit losses: Three Months Ended Beginning balance $ 44,661 $ 12,238 $ 51,807 $ 5,971 $ 14,758 $ 3,421 $ 5,469 $ 1,041 $ 2,476 $ 141,842 Charge-offs 168 — 1,085 90 — 1,411 173 446 — 3,373 Recoveries 1,510 463 518 528 112 652 283 229 — 4,295 Provision (5,313 ) (558 ) 6,980 1,722 (11 ) 962 (267 ) 367 (148 ) 3,734 Ending balance $ 40,690 $ 12,143 $ 58,220 $ 8,131 $ 14,859 $ 3,624 $ 5,312 $ 1,191 $ 2,328 $ 146,498 Ending allowance balance attributable to loans: Individually evaluated for impairment $ 986 $ — $ 286 $ 2,192 $ — $ — $ 2,634 $ — $ 541 $ 6,639 Collectively evaluated for impairment 39,545 12,143 57,799 5,939 14,824 3,624 2,678 1,191 1,787 139,530 Acquired and accounted for under ASC 310-30 (1) 159 — 135 — 35 — — — — 329 Total ending allowance balance $ 40,690 $ 12,143 $ 58,220 $ 8,131 $ 14,859 $ 3,624 $ 5,312 $ 1,191 $ 2,328 $ 146,498 Loans: Individually evaluated for impairment $ 15,214 $ 729 $ 10,160 $ 15,803 $ — $ 108 $ 28,437 $ — $ — $ 70,451 Collectively evaluated for impairment 4,348,908 2,007,872 3,724,011 1,211,415 554,942 573,684 218,368 80,016 — 12,719,216 Acquired and accounted for under ASC 310-30 (1) 24,768 — 46,683 77,332 5,624 — 12,382 2,025 — 168,814 Total ending loans balance $ 4,388,890 $ 2,008,601 $ 3,780,854 $ 1,304,550 $ 560,566 $ 573,792 $ 259,187 $ 82,041 $ — $ 12,958,481 (1) Loans acquired in business combinations and accounted for under ASC Subtopic 310-30 “Receivables — Loans and Debt Securities Acquired with Deteriorated Credit Quality.”
Changes in the Accretable Yield for Purchased Credit-Impaired Loans	Changes in the accretable yield for loans acquired and accounted for under ASC 310-30 were as follows for the three months ended March 31, 2018 and 2017 (in thousands): Three Months Ended March 31, 2018 2017 Balance at beginning of period $ 12,069 $ 16,050 Purchases — 43 Accretion (2,411 ) (2,188 ) Other (1) 609 1,006 Balance at end of period $ 10,267 $ 14,911 (1) Primarily includes discount transfers from non-accretable discount to accretable discount due to better than expected performance of loan pools acquired and accounted for under ASC 310-30.
Carrying Amount of Loans Acquired Through a Business Combination by Loan Pool Type	The carrying amount of loans acquired through a business combination by loan pool type are as follows (in thousands): March 31, 2018 Purchased Purchased Non-Credit-Impaired Total Covered loans (1) : Consumer related $ 14,449 $ — $ 14,449 Non-covered loans: Commercial loans 10,877 210,070 220,947 Commercial loans collateralized by assignment of lease payments — 30,534 30,534 Commercial real estate 24,648 703,127 727,775 Construction real estate 4,980 4,743 9,723 Consumer related 5,562 252,660 258,222 Total non-covered loans 46,067 1,201,134 1,247,201 Total acquired $ 60,516 $ 1,201,134 $ 1,261,650 (1) Covered loans refer to loans covered under loss-sharing agreements with the FDIC. The loss-share agreements expire between 2019 and 2020.

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Carrying Amount of Goodwill	The following table presents the carrying amount of goodwill by segment for the three months ended March 31, 2018 (in thousands): Banking Leasing Mortgage Banking Total Balance at end of period $ 959,285 $ 40,640 $ 3,623 $ 1,003,548
Changes in the Carrying Amount of Core Deposit and Client Relationship Intangibles	The following table presents the changes during the three months ended March 31, 2018 in the carrying amount of core deposit and client relationship intangibles, and the gross carrying amount, accumulated amortization, and net book value as of March 31, 2018 (in thousands): March 31, 2018 Balance at beginning of period $ 54,766 Amortization expense (1,902 ) Balance at end of period $ 52,864 Gross carrying amount $ 112,820 Accumulated amortization (59,956 ) Net book value $ 52,864
Estimated Future Amortization Expense of Other Intangible Assets	The following presents the estimated future amortization expense of other intangible assets (in thousands): Year ending December 31, Amount 2018 $ 5,549 2019 5,674 2020 5,022 2021 4,790 2022 3,806 Thereafter 28,023 $ 52,864

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Schedule of Composition of Deposits	The composition of deposits was as follows as of March 31, 2018 and December 31, 2017 (in thousands): March 31, December 31, 2018 2017 Demand deposit accounts, non-interest bearing $ 6,385,149 $ 6,381,512 NOW, money market, and interest bearing deposits 4,858,506 4,954,765 Savings accounts 1,229,968 1,167,810 Certificates of deposit, $250,000 or more 1,519,552 1,506,071 Other certificates of deposit 977,418 948,220 Total $ 14,970,593 $ 14,958,378

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Summary of Short-Term Borrowings	Short-term borrowings were as follows as of March 31, 2018 and December 31, 2017 (dollars in thousands): March 31, 2018 December 31, 2017 Weighted Average Interest Rate Amount Weighted Average Interest Rate Amount Customer repurchase agreements 0.38 % $ 225,962 0.27 % $ 232,789 Federal Home Loan Bank advances 1.85 365,000 1.31 625,000 Federal funds purchased 1.69 126,717 1.26 3,250 Line of credit — — — — Total 1.36 % $ 717,679 1.03 % $ 861,039

Long-Term Borrowings (Tables)

Long-Term Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Borrowings	Long-term borrowings were as follows as of March 31, 2018 and December 31, 2017 (dollars in thousands): March 31, 2018 December 31, 2017 Weighted Average Interest Rate Amount Weighted Average Interest Rate Amount Federal Home Loan Bank advances 2.24 % $ 591,266 1.73 % $ 231,317 Notes payable 4.21 87,017 4.14 90,807 Subordinated notes, net of issuance costs (1) 4.00 172,938 4.00 173,034 Term note — — 3.31 10,000 Total 2.80 % $ 851,221 2.97 % $ 505,158 (1) The amount decreased from December 31, 2017 as a result of an increase in issuance costs due to adjustments for actual costs.

Junior Subordinated Notes Iss34

Junior Subordinated Notes Issued to Capital Trusts (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Outstanding Junior Subordinated Notes and the Related Trust Preferred Securities Issued by Each Trust	The table below summarizes the outstanding junior subordinated notes and the related trust preferred securities issued by each trust as of March 31, 2018 (in thousands): Coal City Capital Trust I MB Financial Capital Trust II MB Financial Capital Trust III MB Financial Capital Trust IV Junior Subordinated Notes: Principal balance $ 25,774 $ 36,083 $ 10,310 $ 20,619 Annual interest rate 3-mo LIBOR + 1.80% 3-mo LIBOR + 1.40% 3-mo LIBOR + 1.50% 3-mo LIBOR + 1.52% Stated maturity date September 1, 2028 September 15, 2035 September 23, 2036 September 15, 2036 Call date September 1, 2008 December 15, 2010 September 23, 2011 September 15, 2011 Trust Preferred Securities: Face Value $ 25,000 $ 35,000 $ 10,000 $ 20,000 Annual distribution rate 3-mo LIBOR + 1.80% 3-mo LIBOR + 1.40% 3-mo LIBOR + 1.50% 3-mo LIBOR + 1.52% Issuance date July 1998 August 2005 July 2006 August 2006 Distribution dates (1) Quarterly Quarterly Quarterly Quarterly MB Financial Capital Trust V MB Financial Capital Trust VI FOBB Statutory Trust III (2) TAYC Capital Trust II (3) Junior Subordinated Notes: Principal balance $ 30,928 $ 23,196 $ 5,155 $ 41,238 Annual interest rate 3-mo LIBOR + 1.30% 3-mo LIBOR + 1.30% 3-mo LIBOR + 2.80% 3-mo LIBOR + 2.68% Stated maturity date December 15, 2037 October 30, 2037 January 23, 2034 June 17, 2034 Call date December 15, 2012 October 30, 2012 January 23, 2009 June 17, 2009 Trust Preferred Securities: Face Value $ 30,000 $ 22,500 $ 5,000 $ 40,000 Annual distribution rate 3-mo LIBOR + 1.30% 3-mo LIBOR + 1.30% 3-mo LIBOR + 2.80% 3-mo LIBOR + 2.68% Issuance date September 2007 October 2007 December 2003 June 2004 Distribution dates (1) Quarterly Quarterly Quarterly Quarterly American Chartered Statutory Trust II (4) Junior Subordinated Notes: Principal balance $ 10,310 Annual interest rate 3-mo LIBOR + 2.75% Stated maturity date October 7, 2034 Call date October 7, 2009 Trust Preferred Securities: Face Value $ 10,000 Annual distribution rate 3-mo LIBOR + 2.75% Issuance date August 2004 Distribution dates (1) Quarterly (1) All distributions are cumulative and paid in cash. (2) FOBB Statutory Trust III was established by First Oak Brook Bancshares, Inc. (“FOBB”) prior to the Company's acquisition of FOBB in 2006, and the junior subordinated notes issued by FOBB to FOBB Statutory Trust III were assumed by the Company upon completion of the acquisition. (3) TAYC Capital Trust II was established by Taylor Capital Group, Inc. (“Taylor Capital”) prior to the Company's acquisition of Taylor Capital in 2014, and the junior subordinated notes issued by Taylor Capital to TAYC Capital Trust II were assumed by the Company upon completion of the acquisition. Principal balance and face value amounts associated with TAYC Capital Trust II do not include purchase accounting adjustments to such amounts, which in each case resulted in a remaining discount of $6.3 million at March 31, 2018 . (4) American Chartered Statutory Trust II was established by American Chartered prior to the Company's acquisition of American Chartered in August 2016, and the junior subordinated notes issued by American Chartered to American Chartered Statutory Trust II were assumed by the Company upon completion of the acquisition. Principal balance and face value amounts associated with American Chartered Statutory Trust II do not include acquisition accounting adjustments to such amounts, which in each case resulted in a remaining discount of $2.7 million at March 31, 2018 .

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Outstanding Financial Instruments, Contractual Amounts of Off-Balance Sheet Credit Risk	At March 31, 2018 and December 31, 2017 , the following financial instruments were outstanding, the contractual amounts of which represent off-balance sheet credit risk (in thousands): Contractual Amount March 31, 2018 December 31, 2017 Commitments to extend credit: Home equity lines $ 198,649 $ 203,922 Other commitments 3,965,840 4,073,044 Letters of credit: Standby 161,752 161,014 Commercial 666 2,248

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis	The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 , segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) March 31, 2018 Financial assets Securities available for sale: U.S Government sponsored agencies and enterprises $ 22,885 $ — $ 22,885 $ — States and political subdivisions 366,906 — 366,577 329 Residential mortgage-backed securities 1,187,068 — 1,187,049 19 Commercial mortgage-backed securities 64,161 — 64,161 — Corporate bonds 37,991 — 37,991 — Marketable equity securities 11,124 11,124 — — Loans held for sale 561,549 — 561,549 — Loans 39,206 — 39,206 — Mortgage servicing rights 291,561 — — 291,561 Assets held in trust for deferred compensation 23,324 23,324 — — Derivative financial instruments 49,005 1,082 45,642 2,281 Financial liabilities Other liabilities (1) 23,324 23,324 — — Derivative financial instruments 46,181 2,130 44,051 — December 31, 2017 Financial assets Securities available for sale: U.S. Government sponsored agencies and enterprises $ 23,007 $ — $ 23,007 $ — States and political subdivisions 379,325 — 378,996 329 Residential mortgage-backed securities 852,699 — 852,665 34 Commercial mortgage-backed securities 72,035 — 72,035 — Corporate bonds 70,197 — 70,197 — Equity securities 11,063 11,063 — — Loans held for sale 548,578 — 548,578 — Loans 40,531 — 40,531 — Mortgage servicing rights 276,279 — — 276,279 Assets held in trust for deferred compensation 21,410 21,410 — — Derivative financial instruments 31,499 389 29,539 1,571 Financial liabilities Other liabilities (1) 21,410 21,410 — — Derivative financial instruments 40,296 1,072 39,224 — (1) Liabilities associated with assets held in trust for deferred compensation
Summary of Financial Assets Measured at Fair Value on a Recurring Basis, Unobservable Inputs Used	The following table presents additional information about the unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy (fair value in thousands): Fair Value at Valuation March 31, 2018 Technique Unobservable Input Range Impaired loans $ 58,717 Appraisal of collateral Appraisal adjustments - sales costs 5% - 10% Foreclosed assets 15,374 Appraisal of collateral Appraisal adjustments - sales costs 5% - 10% The following table presents additional information about the unobservable inputs used in the fair value measurement of financial assets measured on a recurring basis that were categorized within the Level 3 of the fair value hierarchy (fair value in thousands): Fair Value at March 31, 2018 Valuation Technique Unobservable Input Range States and political subdivisions $ 329 Discounted cash flows Credit assumption 40% - 45% Loss Residential mortgage-backed securities 19 Discounted cash flows Constant pre-payment rates (CPR) 1% - 3% Mortgage servicing rights 291,561 Discounted cash flows CPR 6.35% - 6.84% Discount rate 9.53 - 11.06 Maturity (months) 325 - 358 Delinquency rate 2.05 - 4.78 Costs to service $ 67 - $ 227 Additive delinquent costs to service $ 175 - $ 1,000 Derivative financial instruments (mortgage 2,281 Sales cash flows Expected closing ratio 70% - 95% interest rate lock commitments) Expected delivery price 93.12 bps - 106.62 bps Fair Value at December 31, 2017 Valuation Technique Unobservable Input Range States and political subdivisions $ 329 Discounted cash flows Credit assumption 40-45% Loss Residential mortgage-backed securities 34 Discounted cash flows Constant pre-payment rates (CPR) 1% - 3% Mortgage servicing rights 276,279 Discounted cash flows CPR 6.7% - 7.8% Discount rate 9.53 - 11.06 Maturity (months) 324 - 358 Delinquency rate 2.42 - 5.30 Costs to service $ 67 - $ 227 Additive delinquent costs to service $ 175 - $ 1,000 Derivative financial instruments (mortgage 1,571 Sales cash flows Expected closing ratio 70% - 95% interest rate lock commitments) Expected delivery price 97.38 bps - 106.87 bps
Schedule of Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets	Key economic assumptions used in the measuring of the fair value of the mortgage servicing rights and the sensitivity of the fair value to immediate adverse changes in those assumptions at March 31, 2018 are presented in the following table. This table does not take into account the derivatives used to economically hedge the mortgage servicing rights. (dollars in thousands, except for weighted average cost to service) March 31, 2018 Weighted average CPR 6.52 % Impact on fair value of 10% adverse change $ (8,500 ) Impact on fair value of 20% adverse change (16,583 ) Weighted average discount rate 9.82 % Impact on fair value of 10% adverse change $ (12,400 ) Impact on fair value of 20% adverse change (23,803 ) Weighted average delinquency rate 4.56 % Impact on fair value of 10% adverse change $ (3,960 ) Impact on fair value of 20% adverse change (6,298 ) Weighted average costs to service $ 91.25 Impact on fair value of 10% adverse change (5,454 ) Impact on fair value of 20% adverse change (10,908 )
Financial Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)	The following table presents additional information about financial assets measured at fair value on a recurring basis for which the Company used significant unobservable inputs (Level 3): Three Months Ended March 31, 2018 2017 2018 2017 2018 2017 (in thousands) Investment Securities Mortgage Servicing Rights Derivatives Balance, beginning of period $ 363 $ 544 $ 276,279 $ 238,011 $ 1,571 $ 3,160 Purchases — — 67 496 — — Originations — — 12,340 15,651 — — Included in earnings — — 2,875 (2,660 ) 710 2,451 Principal payments (15 ) (35 ) — — — — Sales — — — — — — Balance, ending of period $ 348 $ 509 $ 291,561 $ 251,498 $ 2,281 $ 5,611
Assets Measured at Fair Value on a Nonrecurring Basis	Assets measured at fair value on a nonrecurring basis as of March 31, 2018 and December 31, 2017 are included in the table below (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) March 31, 2018 Financial assets: Impaired loans $ 58,717 $ — $ — $ 58,717 Non-financial assets: Foreclosed assets 15,374 — — 15,374 December 31, 2017 Financial assets: Impaired loans $ 60,569 $ — $ — $ 60,569 Non-financial assets: Foreclosed assets 15,113 — — 15,113
Estimated Fair Values of Financial Instruments	The estimated fair values of financial instruments are as follows (in thousands): March 31, 2018 Carrying Amount Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Cash and due from banks $ 332,234 $ 332,234 $ 332,234 $ — $ — Interest earning deposits with banks 50,624 50,624 50,624 — — Investment securities available for sale 1,679,011 1,679,011 — 1,678,663 348 Investment securities held to maturity 933,319 950,806 — 950,806 — Marketable equity securities 11,124 11,124 11,124 — — Non-marketable securities - FHLB and FRB stock 118,955 118,955 — — 118,955 Loans held for sale 561,549 561,549 — 561,549 — Loans, net 13,773,268 13,873,378 — 39,206 13,834,172 Accrued interest receivable 65,445 65,445 65,445 — — Derivative financial instruments 49,005 49,005 1,082 45,642 2,281 Financial Liabilities: Non-interest bearing deposits $ 6,385,149 $ 6,385,149 $ 6,385,149 $ — $ — Interest bearing deposits 8,585,444 8,574,742 — — 8,574,742 Short-term borrowings 717,679 717,400 — — 717,400 Long-term borrowings 851,221 855,337 — — 855,337 Junior subordinated notes issued to capital trusts 194,304 156,323 — — 156,323 Accrued interest payable 8,352 8,352 8,352 — — Derivative financial instruments 46,181 46,181 2,130 44,051 — December 31, 2017 Carrying Amount Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Cash and due from banks $ 397,880 $ 397,880 $ 397,880 $ — $ — Interest earning deposits with banks 181,341 181,341 181,341 — — Investment securities available for sale 1,408,326 1,408,326 11,063 1,396,900 363 Investment securities held to maturity 959,082 992,455 — 992,455 — Non-marketable securities - FHLB and FRB stock 114,111 114,111 — — 114,111 Loans held for sale 548,578 548,578 — 548,578 — Loans, net 13,808,352 13,988,392 — 40,531 13,947,861 Accrued interest receivable 63,589 63,589 63,589 — — Derivative financial instruments 31,499 31,499 389 29,539 1,571 Financial Liabilities: Non-interest bearing deposits $ 6,381,512 $ 6,381,512 $ 6,381,512 $ — $ — Interest bearing deposits 8,576,866 8,569,368 — — 8,569,368 Short-term borrowings 861,039 860,676 — — 860,676 Long-term borrowings 505,158 513,725 — — 513,725 Junior subordinated notes issued to capital trusts 211,494 170,965 — — 170,965 Accrued interest payable 6,458 6,458 6,458 — — Derivative financial instruments 40,296 40,296 1,072 39,224 —

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-Based Payment Plans	The following table summarizes the impact of the Company’s share-based payment plans in the financial statements for the periods shown (in thousands): Three Months Ended March 31, 2018 2017 Total compensation expense for share-based payment plans during the period $ 4,451 $ 4,481 Amount of related income tax benefit recognized in income (1) 1,354 4,422 (1) Includes tax benefits recorded for the vesting of restricted shares and exercise of options.
Summary of Changes in Stock Options	The following table summarizes changes in stock options for the three months ended March 31, 2018 : Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value (in thousands) Options outstanding as of December 31, 2017 1,721,978 $ 29.10 5.19 Granted 156,687 41.00 Exercised (95,749 ) 27.24 Expired (1,092 ) 39.28 Forfeited or cancelled (4,764 ) 30.22 Options outstanding as of March 31, 2018 1,777,060 $ 30.24 5.53 $ 19,173 Options exercisable as of March 31, 2018 1,265,177 $ 27.71 4.32 $ 16,468
Assumptions Used for Options Granted	The following assumptions were used for options granted during the three months ended March 31, 2018 : March 31, 2018 Risk-free interest rate 2.80 % Expected volatility of Company’s stock 25.98 % Expected dividend yield 2.06 % Expected life of options 5.9 years Weighted average fair value per option of options granted during the year $ 9.61
Summary of Changes in Restricted Shares and Units	The following is a summary of changes in restricted shares and units for the three months ended March 31, 2018 : Number of Shares and Units Weighted Average Grant Date Fair Value Shares and units outstanding at December 31, 2017 973,201 $ 37.03 Granted 414,012 41.44 Vested (297,033 ) 34.91 Forfeited or cancelled (80,035 ) 34.38 Shares and units outstanding at March 31, 2018 1,010,145 39.67

Derivative Financial Instrume38

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Derivative Financial Instruments	The Company’s derivative financial instruments are summarized below as of March 31, 2018 and December 31, 2017 (in thousands): Asset Derivatives Liability Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Notional Estimated Notional Estimated Notional Estimated Notional Estimated Amount Fair Value Amount Fair Value Amount Fair Value Amount Fair Value Derivative instruments designated as hedges of fair value: Interest rate swap contracts (1) $ — $ — $ — $ — $ 45 $ (1 ) $ 58 $ (1 ) Stand-alone derivative instruments: (2) Interest rate swap contracts 1,647,481 28,308 1,563,109 21,217 1,647,481 (28,308 ) 1,563,109 (21,217 ) Interest rate options contracts 402,633 3,326 372,927 1,887 402,566 (3,326 ) 372,927 (1,887 ) Foreign exchange contracts 57,689 3,879 40,713 1,934 56,866 (3,695 ) 34,029 (1,759 ) Spot foreign exchange contracts 503 20 1,424 23 117 (12 ) 24 — Mortgage related derivatives: Interest rate swap contracts 275,000 9,234 458,000 4,479 270,000 (8,709 ) 1,008,000 (14,360 ) Interest rate swaptions contracts 290,000 875 — — — — — — Treasury futures contracts 20,000 100 28,000 39 — — 30,000 (222 ) TBA mortgage securities 50,000 406 15,000 16 — — 100,000 (63 ) Forward loan sale commitments 126,000 576 259,000 333 606,500 (2,130 ) 483,500 (787 ) Interest rate lock commitments 499,337 2,281 404,557 1,571 — — — — Total stand-alone derivative instruments 3,368,643 49,005 3,142,730 31,499 2,983,530 (46,180 ) 3,591,589 (40,295 ) Total $ 3,368,643 $ 49,005 $ 3,142,730 $ 31,499 $ 2,983,575 $ (46,181 ) $ 3,591,647 $ (40,296 ) (1) Derivative instruments designated to hedge fixed-rate commercial real estate loans. (2) These portfolio swaps are not designated as hedging instruments under ASC Topic 815.
Schedule of the Amounts Included in Consolidated Statements of Operations Related to Derivative Financial Instruments	Amounts included in other operating income in the consolidated statements of operations related to derivative financial instruments were as follows (in thousands): Three Months Ended March 31, 2018 2017 Derivative instruments designated as hedges of fair value: Interest rate swap contracts $ — $ 1 Stand-alone derivative instruments: Interest rate swap contracts 1,715 1,849 Interest rate options contracts — — Foreign exchange contracts 43 63 Spot foreign exchange contracts 733 678 Mortgage related derivatives (581 ) (10,141 ) Total stand-alone derivative instruments 1,910 (7,551 ) Total $ 1,910 $ (7,550 )
Schedule of Financial Instruments Eligible for Offset In the Consolidated Balance Sheet	Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of March 31, 2018 is summarized below (in thousands): Financial Assets Financial Liabilities Gross Amount Recognized Gross Amount Offset Net Amount Recognized Gross Amount Recognized Gross Amount Offset Net Amount Recognized Derivatives: Interest rate swap contracts, caps and floors $ 26,570 $ — $ 26,570 $ 4,976 $ — $ 4,976 Foreign exchange contracts 414 — 414 3,475 — 3,475 Mortgage related derivatives 11,190 — 11,190 10,839 — 10,839 Total derivatives 38,174 — 38,174 19,290 — 19,290 Repurchase agreements — — — 225,962 — 225,962 Total $ 38,174 $ — $ 38,174 $ 245,252 $ — $ 245,252 Financial Assets Financial Liabilities Net Amount Recognized Financial Instruments Collateral Net Amount Net Amount Recognized Financial Instruments Collateral Net Amount Derivatives: Counterparty A $ 13,664 $ (7,524 ) $ — $ 6,140 $ 7,524 $ (7,524 ) $ — $ — Counterparty B 10,301 (585 ) — 9,716 585 (585 ) — — Counterparty C 7,999 (5,616 ) (2,383 ) — 5,616 (5,616 ) — — Other counterparties 6,210 (2,768 ) (2,308 ) 1,134 5,565 (2,768 ) (1,308 ) 1,489 Total derivatives 38,174 (16,493 ) (4,691 ) 16,990 19,290 (16,493 ) (1,308 ) 1,489 Repurchase agreements — — — — 225,962 — (225,962 ) — Total $ 38,174 $ (16,493 ) $ (4,691 ) $ 16,990 $ 245,252 $ (16,493 ) $ (227,270 ) $ 1,489 Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2017 is summarized below (in thousands): Financial Assets Financial Liabilities Gross Amount Recognized Gross Amount Offset Net Amount Recognized Gross Amount Recognized Gross Amount Offset Net Amount Recognized Derivatives: Interest rate swap contracts, caps and floors $ 11,659 $ — $ 11,659 $ 11,562 $ — $ 11,562 Foreign exchange contracts 1,013 — 1,013 953 — 953 Mortgage related derivatives 4,868 — 4,868 15,432 — 15,432 Total derivatives 17,540 — 17,540 27,947 — 27,947 Repurchase agreements — — — 232,789 — 232,789 Total $ 17,540 $ — $ 17,540 $ 260,736 $ — $ 260,736 Financial Assets Financial Liabilities Net Amount Recognized Financial Instruments Collateral Net Amount Net Amount Recognized Financial Instruments Collateral Net Amount Derivatives: Counterparty A $ 6,068 $ (6,068 ) $ — $ — $ 13,807 $ (6,068 ) $ (7,739 ) $ — Counterparty B 3,261 (3,261 ) — — 5,595 (3,261 ) (2,334 ) — Counterparty C 5,285 (3,640 ) — 1,645 3,640 (3,640 ) — — Other counterparties 2,926 (1,750 ) — 1,176 4,905 (1,750 ) (3,150 ) 5 Total derivatives 17,540 (14,719 ) — 2,821 27,947 (14,719 ) (13,223 ) 5 Repurchase agreements — — — — 232,789 — (232,789 ) — Total $ 17,540 $ (14,719 ) $ — $ 2,821 $ 260,736 $ (14,719 ) $ (246,012 ) $ 5

Operating Segments (Tables)

Operating Segments (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Summary Financial Information for the Reportable Segments	The following tables present summary financial information for the reportable segments (in thousands): Banking Leasing Mortgage Banking Consolidated Three months ended March 31, 2018 Net interest income $ 140,471 $ 2,482 $ 10,428 $ 153,381 Provision for credit losses 7,579 (24 ) (47 ) 7,508 Non-interest income 43,092 24,856 24,854 92,802 Non-interest expense (1) 115,826 15,496 36,564 167,886 Income tax expense 13,608 756 (332 ) 14,032 Net income $ 46,550 $ 11,110 $ (903 ) $ 56,757 Total assets $ 16,582,585 $ 1,360,117 $ 2,224,821 $ 20,167,523 Three months ended March 31, 2017 Net interest income $ 131,449 $ 2,269 $ 9,325 $ 143,043 Provision for credit losses 3,527 (135 ) 342 3,734 Non-interest income 43,208 21,463 27,779 92,450 Non-interest expense (1) 108,516 13,844 33,982 156,342 Income tax expense 15,660 4,119 1,101 20,880 Net income $ 46,954 $ 5,904 $ 1,679 $ 54,537 Total assets $ 16,009,339 $ 1,173,558 $ 1,963,165 $ 19,146,062 (1) Includes merger related and repositioning expenses of $644 thousand and $258 thousand in the Banking Segment for the three months ended March 31, 2018 and 2017 , respectively.

New Authoritative Accounting 40

New Authoritative Accounting Guidance (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Retained earnings	$ 1,112,323		$ 1,065,303
Cumulative effect of accounting changes			(298)
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of accounting changes			1,336
Retained Earnings
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of accounting changes			(1,634)
Accounting Standards Update 2014-09 | Difference Between Revenue Guidance In Effect Before And After Topic 606
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Retained earnings			$ (683)
Accounting Standards Update, 2016-01
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Retained earnings		$ 385
Accounting Standards Update, 2016-01 | Accumulated Other Comprehensive Income (Loss), Net of Tax
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of accounting changes		(1,200)
Accounting Standards Update, 2016-01 | Retained Earnings
Accounting Changes and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of accounting changes		$ 1,200

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 18, 2014	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income		$ 56,757	$ 54,537
Less: preferred stock dividends		3,100	2,003
Plus: return from preferred stockholders due to redemption		15,280	0
Net income available to common stockholders		68,937	52,534
Plus: preferred stock dividends on convertible preferred stock		0	3
Earnings allocated to common stockholders for diluted earnings per common share		$ 68,935	$ 52,536
Weighted average shares outstanding for basic earnings per common share (in shares)		84,065,681	83,662,430
Dilutive effect of convertible preferred stock (in shares)		0	7,322
Total dilutive effect of equity awards and convertible preferred stock (in shares)		830,720	1,115,700
Weighted average shares outstanding for diluted earnings per common share (in shares)		84,896,401	84,778,130
Basic earnings per common share (in dollars per share)		$ 0.82	$ 0.63
Diluted earnings per common share (in dollars per share)		$ 0.81	$ 0.62
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of stock options and restricted shares/units (in shares)		507,786	636,515
Restricted shares and units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of stock options and restricted shares/units (in shares)		322,934	471,863
Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distributed earnings allocated to common stock		$ 20,283	$ 16,131
Undistributed earnings		36,474	38,406
Net income		56,757	54,537
Net income available to common stockholders		$ 68,937	$ 52,534
Weighted average shares outstanding for basic earnings per common share (in shares)		84,065,681	83,662,430
Weighted average shares outstanding for diluted earnings per common share (in shares)		84,896,401	84,778,130
Participating Securities
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Less: earnings allocated to participating securities		$ 2	$ 1
Series A Preferred Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Preferred stock, dividend rate (percent)	8.00%	8.00%		8.00%

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Available for Sale
Amortized Cost	$ 1,682,421	$ 1,401,365
Gross Unrealized Gains	15,037	19,732
Gross Unrealized Losses	(18,447)	(12,771)
Fair Value	1,679,011	1,408,326
Held to Maturity
Amortized Cost	933,319	959,082
Gross Unrealized Gains	19,397	33,820
Gross Unrealized Losses	(1,910)	(447)
Fair Value	950,806	992,455
Total Available for Sale and Held to Maturity Investment Securities
Amortized Cost	2,615,740	2,360,447
Gross Unrealized Gains	34,434	53,552
Gross Unrealized Losses	(20,357)	(13,218)
Fair Value	2,629,817	2,400,781
U.S. Government sponsored agencies and enterprises
Available for Sale
Amortized Cost	22,948	23,013
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(63)	(9)
Fair Value	22,885	23,007
States and political subdivisions
Available for Sale
Amortized Cost	355,058	363,813
Gross Unrealized Gains	12,478	15,998
Gross Unrealized Losses	(630)	(486)
Fair Value	366,906	379,325
Held to Maturity
Amortized Cost	874,306	878,400
Gross Unrealized Gains	18,704	32,559
Gross Unrealized Losses	(1,910)	(447)
Fair Value	$ 891,100	910,512
Total Available for Sale and Held to Maturity Investment Securities
Percentage of securities consisting general obligation issues	95.00%
Percentage of securities insured	26.00%
States and political subdivisions | State of Illinois | Securities Portfolio
Total Available for Sale and Held to Maturity Investment Securities
Percentage of investments issued by states and political subdivisions that were within the state of Illinois	19.00%
Residential mortgage-backed securities
Available for Sale
Amortized Cost	$ 1,202,251	861,594
Gross Unrealized Gains	2,331	3,035
Gross Unrealized Losses	(17,514)	(11,930)
Fair Value	1,187,068	852,699
Held to Maturity
Amortized Cost	59,013	80,682
Gross Unrealized Gains	693	1,261
Gross Unrealized Losses	0	0
Fair Value	59,706	81,943
Commercial mortgage-backed securities
Available for Sale
Amortized Cost	64,144	71,554
Gross Unrealized Gains	227	612
Gross Unrealized Losses	(210)	(131)
Fair Value	64,161	72,035
Corporate bonds
Available for Sale
Amortized Cost	38,020	70,155
Gross Unrealized Gains	1	84
Gross Unrealized Losses	(30)	(42)
Fair Value	$ 37,991	70,197
Equity securities
Available for Sale
Amortized Cost		11,236
Gross Unrealized Gains		0
Gross Unrealized Losses		(173)
Fair Value		$ 11,063

Investment Securities - Unreali

Investment Securities - Unrealized Losses on Investment Securities and Fair Value of Related Securities (Details) $ in Thousands	Mar. 31, 2018USD ($)Security_Position	Dec. 31, 2017USD ($)Security_Position
Available for Sale
Less Than 12 Months, Fair Value	$ 535,221	$ 308,494
Less Than 12 Months, Unrealized Losses	(4,315)	(2,092)
12 Months or More, Fair Value	429,971	450,524
12 Months or More, Unrealized Losses	(14,132)	(10,679)
Total Fair Value	965,192	759,018
Total Unrealized Losses	(18,447)	(12,771)
Total
Less Than 12 Months, Fair Value	694,185	353,993
Less Than 12 Months, Unrealized Losses	(5,770)	(2,349)
12 Months or More, Fair Value	441,602	463,085
12 Months or More, Unrealized Losses	(14,587)	(10,869)
Total Fair Value	1,135,787	817,078
Total Unrealized Losses	$ (20,357)	$ (13,218)
Number of security positions in the investment portfolio in an unrealized loss position | Security_Position	630	471
U.S. Government sponsored agencies and enterprises
Available for Sale
Less Than 12 Months, Fair Value	$ 22,885	$ 5,111
Less Than 12 Months, Unrealized Losses	(63)	(9)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Total Fair Value	22,885	5,111
Total Unrealized Losses	(63)	(9)
States and political subdivisions
Available for Sale
Less Than 12 Months, Fair Value	18,110	9,016
Less Than 12 Months, Unrealized Losses	(69)	(29)
12 Months or More, Fair Value	18,586	18,754
12 Months or More, Unrealized Losses	(561)	(457)
Total Fair Value	36,696	27,770
Total Unrealized Losses	(630)	(486)
Held to Maturity
Less Than 12 Months, Fair Value	158,964	45,499
Less Than 12 Months, Unrealized Losses	(1,455)	(257)
12 Months or More, Fair Value	11,631	12,561
12 Months or More, Unrealized Losses	(455)	(190)
Total Fair Value	170,595	58,060
Total Unrealized Losses	(1,910)	(447)
Residential mortgage-backed securities
Available for Sale
Less Than 12 Months, Fair Value	442,766	256,769
Less Than 12 Months, Unrealized Losses	(4,035)	(1,853)
12 Months or More, Fair Value	390,083	407,224
12 Months or More, Unrealized Losses	(13,479)	(10,077)
Total Fair Value	832,849	663,993
Total Unrealized Losses	(17,514)	(11,930)
Commercial mortgage-backed securities
Available for Sale
Less Than 12 Months, Fair Value	32,416	19,483
Less Than 12 Months, Unrealized Losses	(136)	(20)
12 Months or More, Fair Value	11,322	14,583
12 Months or More, Unrealized Losses	(74)	(111)
Total Fair Value	43,738	34,066
Total Unrealized Losses	(210)	(131)
Corporate bonds
Available for Sale
Less Than 12 Months, Fair Value	19,044	7,052
Less Than 12 Months, Unrealized Losses	(12)	(8)
12 Months or More, Fair Value	9,980	9,963
12 Months or More, Unrealized Losses	(18)	(34)
Total Fair Value	29,024	17,015
Total Unrealized Losses	$ (30)	(42)
Equity securities
Available for Sale
Less Than 12 Months, Fair Value		11,063
Less Than 12 Months, Unrealized Losses		(173)
12 Months or More, Fair Value		0
12 Months or More, Unrealized Losses		0
Total Fair Value		11,063
Total Unrealized Losses		$ (173)

Investment Securities - Net Gai

Investment Securities - Net Gains (Losses) Recognized and Amortized Cost and Fair Value by Contractual Maturity of Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Realized gains	$ 88	$ 237
Realized losses	(262)	(6)
Net (losses) gains	(174)	$ 231
Amortized Cost, Available for sale
Due in one year or less	87,751
Due after one year through five years	142,875
Due after five years through ten years	38,869
Due after ten years	146,531
Amortized Cost	1,682,421		$ 1,401,365
Fair Value, Available for sale
Due in one year or less	87,946
Due after one year through five years	147,296
Due after five years through ten years	39,263
Due after ten years	153,277
Fair Value	1,679,011		1,408,326
Amortized Cost, Held to maturity
Due in one year or less	45,415
Due after one year through five years	176,545
Due after five years through ten years	207,875
Due after ten years	444,471
Investment securities held to maturity	933,319		959,082
Fair value, Held to maturity
Due in one year or less	45,629
Due after one year through five years	182,455
Due after five years through ten years	213,927
Due after ten years	449,089
Fair Value	950,806		992,455
Total Available for Sale and Held to Maturity Investment Securities
Amortized Cost	2,615,740		2,360,447
Fair Value	2,629,817		2,400,781
Pledged financial instruments, not separately reported, securities	679,100		726,100
Pledged financial instruments, not separately reported, securities required to be pledged	587,000		625,200
Transfer of investment securities from held-to-maturity to available-for-sale	2,600
Residential and commercial mortgage-backed securities
Amortized Cost, Available for sale
Amortized Cost	1,266,395
Fair Value, Available for sale
Fair Value	1,251,229
Residential mortgage-backed securities
Amortized Cost, Available for sale
Amortized Cost	1,202,251		861,594
Fair Value, Available for sale
Fair Value	1,187,068		852,699
Amortized Cost, Held to maturity
Investment securities held to maturity	59,013		80,682
Fair value, Held to maturity
Fair Value	$ 59,706		$ 81,943

Loans - Schedule of Composition

Loans - Schedule of Composition of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Loans
Total loans, excluding purchased credit-impaired loans	$ 13,824,990	$ 13,846,318
Purchased credit-impaired loans	109,990	119,744
Total loans	13,934,980	13,966,062	$ 12,958,481
Commercial Portfolio Segment
Loans
Total loans, excluding purchased credit-impaired loans	4,790,803	4,786,180
Total loans	4,801,680		4,388,890
Commercial Portfolio Segment | Collateralized
Loans
Total loans, excluding purchased credit-impaired loans	2,095,189	2,113,135
Total loans	2,095,189		2,008,601
Commercial Real Estate Portfolio Segment | Commercial real estate
Loans
Total loans, excluding purchased credit-impaired loans	4,093,045	4,147,529
Total loans	4,117,693		3,780,854
Commercial Real Estate Portfolio Segment | Construction real estate
Loans
Total loans, excluding purchased credit-impaired loans	479,638	406,849
Total loans	484,618		560,566
Commercial Real Estate Portfolio Segment | Other
Loans
Total loans, excluding purchased credit-impaired loans	942,062	964,326
Consumer Portfolio Segment | Commercial real estate
Loans
Total loans, excluding purchased credit-impaired loans	1,391,900	1,432,458
Consumer Portfolio Segment | Indirect vehicle
Loans
Total loans, excluding purchased credit-impaired loans	692,642	667,928
Total loans	692,642		573,792
Consumer Portfolio Segment | Home equity
Loans
Total loans, excluding purchased credit-impaired loans	202,920	219,098
Total loans	213,403		259,187
Consumer Portfolio Segment | Other
Loans
Total loans, excluding purchased credit-impaired loans	78,853	$ 73,141
Total loans	$ 80,222		$ 82,041

Loans - Additional Information

Loans - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)category	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Receivables [Abstract]
Number of highest rating categories by rating services company | category	1
Number of highest rating categories to be achieved for classification as investment grade companies | category	4
Financing Receivable, Allowance for Credit Losses [Line Items]
Percentage of collateral pledge of first mortgage loans as per agreement (minimum)	160.00%
Percentage of collateral pledge of home equity loans as per agreement (minimum)	170.00%
Percentage of collateral pledge of commercial real estate loans as per agreement (minimum)	161.00%
Percentage of collateral pledge of outstanding advances from federal home loan bank as per agreement (minimum)	106.00%
Loans pledged as collateral for long-term Federal Home Loan Bank advances	$ 4,600,000		$ 4,700,000
Loans required to be pledged as collateral for long-term Federal Home Loan Bank advances	3,400,000		3,100,000
Real estate | Commercial Real Estate Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans secured by owner-occupied properties	1,300,000
Provision for credit losses	(4,083)	$ (6,980)
Purchased Credit-Impaired Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for credit losses	413
Allowance for loan losses and unfunded commitments write offs net of recoveries	170
Allowance for loan losses and unfunded commitments acquired with deteriorated credit quality	$ 934		$ 1,200

Loans - Contractual Aging of Re

Loans - Contractual Aging of Recorded Investment in Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	$ 13,824,990	$ 13,846,318
Total loans	13,934,980	13,966,062	$ 12,958,481
Non-performing loan aging
Contractual aging of the recorded investment in loans
Current	30,610	36,879
Past Due	30,710	39,929
Total loans	61,320	76,808
Non-performing loan aging | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	6,296	8,799
Non-performing loan aging | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	2,157	4,961
Non-performing loan aging | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	22,257	26,169
Purchased credit-impaired loans
Contractual aging of the recorded investment in loans
Current	63,071	63,937
Past Due	46,919	55,807
Total loans	109,990	119,744
Purchased credit-impaired loans | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	10,559	8,749
Purchased credit-impaired loans | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	2,685	3,997
Purchased credit-impaired loans | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	33,675	43,061
Total loans, excluding purchased credit-impaired loans
Contractual aging of the recorded investment in loans
Current	13,715,114	13,762,588
Past Due	109,876	83,730
Total loans, excluding covered loans	13,824,990	13,846,318
Total loans, excluding purchased credit-impaired loans | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	78,878	43,626
Total loans, excluding purchased credit-impaired loans | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	8,741	13,935
Total loans, excluding purchased credit-impaired loans | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	22,257	26,169
Total loans
Contractual aging of the recorded investment in loans
Current	13,778,185	13,826,525
Past Due	156,795	139,537
Total loans	13,934,980	13,966,062
Total loans | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	89,437	52,375
Total loans | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	11,426	17,932
Total loans | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	55,932	69,230
Commercial Portfolio Segment
Contractual aging of the recorded investment in loans
Current	4,751,376	4,769,244
Past Due	39,427	16,936
Total loans, excluding covered loans	4,790,803	4,786,180
Total loans	4,801,680		4,388,890
Commercial Portfolio Segment | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	30,468	1,702
Commercial Portfolio Segment | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	1,195	6,926
Commercial Portfolio Segment | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	7,764	8,308
Commercial Portfolio Segment | Collateralized
Contractual aging of the recorded investment in loans
Current	2,066,953	2,099,246
Past Due	28,236	13,889
Total loans, excluding covered loans	2,095,189	2,113,135
Total loans	2,095,189		2,008,601
Commercial Portfolio Segment | Collateralized | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	22,462	11,320
Commercial Portfolio Segment | Collateralized | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	5,073	1,878
Commercial Portfolio Segment | Collateralized | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	701	691
Commercial Real Estate Portfolio Segment | Health care
Contractual aging of the recorded investment in loans
Current	757,936	710,722
Past Due	0	0
Total loans, excluding covered loans	757,936	710,722
Commercial Real Estate Portfolio Segment | Health care | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Health care | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Health care | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Industrial
Contractual aging of the recorded investment in loans
Current	867,979	908,394
Past Due	2,718	755
Total loans, excluding covered loans	870,697	909,149
Commercial Real Estate Portfolio Segment | Industrial | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	2,718	0
Commercial Real Estate Portfolio Segment | Industrial | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Industrial | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	0	755
Commercial Real Estate Portfolio Segment | Multifamily
Contractual aging of the recorded investment in loans
Current	580,484	601,844
Past Due	164	1,420
Total loans, excluding covered loans	580,648	603,264
Commercial Real Estate Portfolio Segment | Multifamily | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	688
Commercial Real Estate Portfolio Segment | Multifamily | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Multifamily | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	164	732
Commercial Real Estate Portfolio Segment | Retail
Contractual aging of the recorded investment in loans
Current	482,646	503,224
Past Due	1,064	474
Total loans, excluding covered loans	483,710	503,698
Commercial Real Estate Portfolio Segment | Retail | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	835	0
Commercial Real Estate Portfolio Segment | Retail | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Retail | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	229	474
Commercial Real Estate Portfolio Segment | Office
Contractual aging of the recorded investment in loans
Current	454,793	453,960
Past Due	3,199	2,410
Total loans, excluding covered loans	457,992	456,370
Commercial Real Estate Portfolio Segment | Office | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	3,087	0
Commercial Real Estate Portfolio Segment | Office | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	956
Commercial Real Estate Portfolio Segment | Office | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	112	1,454
Commercial Real Estate Portfolio Segment | Other
Contractual aging of the recorded investment in loans
Current	937,356	956,181
Past Due	4,706	8,145
Total loans, excluding covered loans	942,062	964,326
Commercial Real Estate Portfolio Segment | Other | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	3,704	7,035
Commercial Real Estate Portfolio Segment | Other | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	80	76
Commercial Real Estate Portfolio Segment | Other | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	922	1,034
Commercial Real Estate Portfolio Segment | Construction real estate
Contractual aging of the recorded investment in loans
Current	479,066	404,595
Past Due	572	2,254
Total loans, excluding covered loans	479,638	406,849
Total loans	484,618		560,566
Commercial Real Estate Portfolio Segment | Construction real estate | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	572	2,254
Commercial Real Estate Portfolio Segment | Construction real estate | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	0	0
Commercial Real Estate Portfolio Segment | Construction real estate | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	0	0
Consumer Portfolio Segment | Other
Contractual aging of the recorded investment in loans
Current	78,615	72,846
Past Due	238	295
Total loans, excluding covered loans	78,853	73,141
Total loans	80,222		82,041
Consumer Portfolio Segment | Other | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	112	202
Consumer Portfolio Segment | Other | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	71	36
Consumer Portfolio Segment | Other | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	55	57
Consumer Portfolio Segment | Residential real estate
Contractual aging of the recorded investment in loans
Current	1,373,261	1,410,473
Past Due	18,639	21,985
Total loans, excluding covered loans	1,391,900	1,432,458
Total loans	1,449,533		1,304,550
Consumer Portfolio Segment | Residential real estate | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	9,877	12,359
Consumer Portfolio Segment | Residential real estate | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	219	1,907
Consumer Portfolio Segment | Residential real estate | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	8,543	7,719
Consumer Portfolio Segment | Indirect vehicle
Contractual aging of the recorded investment in loans
Current	687,508	661,028
Past Due	5,134	6,900
Total loans, excluding covered loans	692,642	667,928
Total loans	692,642		573,792
Consumer Portfolio Segment | Indirect vehicle | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	3,646	4,905
Consumer Portfolio Segment | Indirect vehicle | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	1,026	1,083
Consumer Portfolio Segment | Indirect vehicle | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	462	912
Consumer Portfolio Segment | Home equity
Contractual aging of the recorded investment in loans
Current	197,141	210,831
Past Due	5,779	8,267
Total loans, excluding covered loans	202,920	219,098
Total loans	213,403		$ 259,187
Consumer Portfolio Segment | Home equity | 30-59 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	1,397	3,161
Consumer Portfolio Segment | Home equity | 60-89 Days Past Due
Contractual aging of the recorded investment in loans
Past Due	1,077	1,073
Consumer Portfolio Segment | Home equity | Loans Past Due 90 Days or More
Contractual aging of the recorded investment in loans
Past Due	$ 3,305	$ 4,033

Loans - Recorded Investment in

Loans - Recorded Investment in Non-Accrual Loans and Loans Past Due (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Contractual aging of the recorded investment in loans
Period past due of recorded investment in loans	90 days
Total loans
Contractual aging of the recorded investment in loans
Non-accrual	$ 60,151	$ 71,238
Loans past due 90 days or more and still accruing	1,169	5,570
Commercial Portfolio Segment
Contractual aging of the recorded investment in loans
Non-accrual	12,654	14,001
Loans past due 90 days or more and still accruing	150	3,500
Commercial Portfolio Segment | Collateralized
Contractual aging of the recorded investment in loans
Non-accrual	672	490
Loans past due 90 days or more and still accruing	367	531
Commercial Real Estate Portfolio Segment | Health care
Contractual aging of the recorded investment in loans
Non-accrual	5,394	0
Loans past due 90 days or more and still accruing	0	0
Commercial Real Estate Portfolio Segment | Industrial
Contractual aging of the recorded investment in loans
Non-accrual	3,433	8,807
Loans past due 90 days or more and still accruing	0	0
Commercial Real Estate Portfolio Segment | Multifamily
Contractual aging of the recorded investment in loans
Non-accrual	277	860
Loans past due 90 days or more and still accruing	0	0
Commercial Real Estate Portfolio Segment | Office
Contractual aging of the recorded investment in loans
Non-accrual	458	2,772
Loans past due 90 days or more and still accruing	0	0
Commercial Real Estate Portfolio Segment | Retail
Contractual aging of the recorded investment in loans
Non-accrual	286	590
Loans past due 90 days or more and still accruing	0	0
Commercial Real Estate Portfolio Segment | Other
Contractual aging of the recorded investment in loans
Non-accrual	1,129	8,016
Loans past due 90 days or more and still accruing	9	190
Commercial Real Estate Portfolio Segment | Construction real estate
Contractual aging of the recorded investment in loans
Non-accrual	0	0
Loans past due 90 days or more and still accruing	0	0
Consumer Portfolio Segment | Residential real estate
Contractual aging of the recorded investment in loans
Non-accrual	19,353	18,374
Loans past due 90 days or more and still accruing	362	1,210
Consumer Portfolio Segment | Indirect vehicle
Contractual aging of the recorded investment in loans
Non-accrual	3,149	3,019
Loans past due 90 days or more and still accruing	5	81
Consumer Portfolio Segment | Home equity
Contractual aging of the recorded investment in loans
Non-accrual	13,338	14,305
Loans past due 90 days or more and still accruing	225	0
Consumer Portfolio Segment | Other
Contractual aging of the recorded investment in loans
Non-accrual	8	4
Loans past due 90 days or more and still accruing	$ 51	$ 58

Loans - Risk Category and Recor

Loans - Risk Category and Recorded Investment of Loans by Class (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans
Commercial related loans, excluding purchased credit-impaired loans	$ 11,458,675	$ 11,453,693
Non-performing substandard and doubtful loans	24,300	35,600
Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	10,970,157	10,997,156
Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	255,990	247,692
Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	232,528	208,845
Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Portfolio Segment
Loans
Commercial related loans, excluding purchased credit-impaired loans	4,790,803	4,786,180
Commercial Portfolio Segment | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	4,503,362	4,535,111
Commercial Portfolio Segment | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	164,489	147,232
Commercial Portfolio Segment | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	122,952	103,837
Commercial Portfolio Segment | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Portfolio Segment | Collateralized
Loans
Commercial related loans, excluding purchased credit-impaired loans	2,095,189	2,113,135
Commercial Portfolio Segment | Collateralized | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	2,075,740	2,095,668
Commercial Portfolio Segment | Collateralized | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	13,828	7,527
Commercial Portfolio Segment | Collateralized | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	5,621	9,940
Commercial Portfolio Segment | Collateralized | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Multifamily
Loans
Commercial related loans, excluding purchased credit-impaired loans	580,648	603,264
Commercial Real Estate Portfolio Segment | Multifamily | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	578,352	595,818
Commercial Real Estate Portfolio Segment | Multifamily | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	858	146
Commercial Real Estate Portfolio Segment | Multifamily | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	1,438	7,300
Commercial Real Estate Portfolio Segment | Multifamily | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Retail
Loans
Commercial related loans, excluding purchased credit-impaired loans	483,710	503,698
Commercial Real Estate Portfolio Segment | Retail | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	472,397	492,830
Commercial Real Estate Portfolio Segment | Retail | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	9,109	8,326
Commercial Real Estate Portfolio Segment | Retail | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	2,204	2,542
Commercial Real Estate Portfolio Segment | Retail | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Office
Loans
Commercial related loans, excluding purchased credit-impaired loans	457,992	456,370
Commercial Real Estate Portfolio Segment | Office | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	452,559	452,902
Commercial Real Estate Portfolio Segment | Office | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	4,975	696
Commercial Real Estate Portfolio Segment | Office | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	458	2,772
Commercial Real Estate Portfolio Segment | Office | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Construction real estate
Loans
Commercial related loans, excluding purchased credit-impaired loans	479,638	406,849
Commercial Real Estate Portfolio Segment | Construction real estate | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	479,638	406,849
Commercial Real Estate Portfolio Segment | Construction real estate | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Construction real estate | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Construction real estate | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Other
Loans
Commercial related loans, excluding purchased credit-impaired loans	942,062	964,326
Commercial Real Estate Portfolio Segment | Other | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	872,138	891,703
Commercial Real Estate Portfolio Segment | Other | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	37,948	37,682
Commercial Real Estate Portfolio Segment | Other | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	31,976	34,941
Commercial Real Estate Portfolio Segment | Other | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Health care
Loans
Commercial related loans, excluding purchased credit-impaired loans	757,936	710,722
Commercial Real Estate Portfolio Segment | Health care | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	684,542	640,751
Commercial Real Estate Portfolio Segment | Health care | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	13,156	33,672
Commercial Real Estate Portfolio Segment | Health care | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	60,238	36,299
Commercial Real Estate Portfolio Segment | Health care | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Commercial Real Estate Portfolio Segment | Industrial
Loans
Commercial related loans, excluding purchased credit-impaired loans	870,697	909,149
Commercial Real Estate Portfolio Segment | Industrial | Pass
Loans
Commercial related loans, excluding purchased credit-impaired loans	851,429	885,524
Commercial Real Estate Portfolio Segment | Industrial | Special Mention
Loans
Commercial related loans, excluding purchased credit-impaired loans	11,627	12,411
Commercial Real Estate Portfolio Segment | Industrial | Substandard
Loans
Commercial related loans, excluding purchased credit-impaired loans	7,641	11,214
Commercial Real Estate Portfolio Segment | Industrial | Doubtful
Loans
Commercial related loans, excluding purchased credit-impaired loans	0	0
Consumer Portfolio Segment
Loans
Commercial related loans, excluding purchased credit-impaired loans	2,366,315	2,392,625
Consumer Portfolio Segment | Performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	2,329,824	2,355,574
Consumer Portfolio Segment | Non-performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	36,491	37,051
Consumer Portfolio Segment | Residential real estate
Loans
Commercial related loans, excluding purchased credit-impaired loans	1,391,900	1,432,458
Consumer Portfolio Segment | Residential real estate | Performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	1,372,185	1,412,874
Consumer Portfolio Segment | Residential real estate | Non-performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	19,715	19,584
Consumer Portfolio Segment | Indirect vehicle
Loans
Commercial related loans, excluding purchased credit-impaired loans	692,642	667,928
Consumer Portfolio Segment | Indirect vehicle | Performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	689,488	664,828
Consumer Portfolio Segment | Indirect vehicle | Non-performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	3,154	3,100
Consumer Portfolio Segment | Home equity
Loans
Commercial related loans, excluding purchased credit-impaired loans	202,920	219,098
Consumer Portfolio Segment | Home equity | Performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	189,357	204,793
Consumer Portfolio Segment | Home equity | Non-performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	13,563	14,305
Consumer Portfolio Segment | Other
Loans
Commercial related loans, excluding purchased credit-impaired loans	78,853	73,141
Consumer Portfolio Segment | Other | Performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	78,794	73,079
Consumer Portfolio Segment | Other | Non-performing
Loans
Commercial related loans, excluding purchased credit-impaired loans	$ 59	$ 62

Loans - Loans Individually Eval

Loans - Loans Individually Evaluated for Impairment by Class of Loans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Loans
Amount of mortgage loans in process of foreclosure	$ 51,400	$ 43,600
Unpaid Principal Balance	82,969	92,635
Recorded Investment	77,246	86,970
Partial Charge-offs	5,723	5,665
Allowance for Loan Losses Allocated	11,224	10,414
Average Recorded Investment	72,182	73,282
Interest Income Recognized	121	904
Performing
Loans
Restructured loans	28,591	28,554
Non-performing
Loans
Restructured loans	28,514	30,836
Impaired financing receivable with no allowance | Commercial Portfolio Segment
Loans
Unpaid Principal Balance	6,055	8,312
Recorded Investment	5,513	7,771
Partial Charge-offs	542	541
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	7,067	5,595
Interest Income Recognized	0	95
Impaired financing receivable with no allowance | Commercial Portfolio Segment | Collateralized
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	301
Interest Income Recognized	0	0
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Health care
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Industrial
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	1,260
Interest Income Recognized	0	8
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Multifamily
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	1,261
Interest Income Recognized	0	29
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Retail
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	814
Interest Income Recognized	0	27
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Office
Loans
Unpaid Principal Balance	0	527
Recorded Investment	0	527
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	1,426
Interest Income Recognized	0	18
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Other
Loans
Unpaid Principal Balance	3,309	10,597
Recorded Investment	3,309	10,597
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	3,325	2,312
Interest Income Recognized	52	128
Impaired financing receivable with no allowance | Commercial Real Estate Portfolio Segment | Construction real estate
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired financing receivable with no allowance | Consumer Portfolio Segment | Real estate
Loans
Unpaid Principal Balance	3,432	1,950
Recorded Investment	3,394	1,912
Partial Charge-offs	38	38
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	3,394	483
Interest Income Recognized	0	0
Impaired financing receivable with no allowance | Consumer Portfolio Segment | Indirect vehicle
Loans
Unpaid Principal Balance	424	408
Recorded Investment	209	202
Partial Charge-offs	215	206
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	479	411
Interest Income Recognized	7	26
Impaired financing receivable with no allowance | Consumer Portfolio Segment | Home equity
Loans
Unpaid Principal Balance	0	81
Recorded Investment	0	81
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	376
Interest Income Recognized	0	0
Impaired financing receivable with no allowance | Consumer Portfolio Segment | Other consumer
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired financing receivable with allowance | Commercial Portfolio Segment
Loans
Unpaid Principal Balance	7,020	7,418
Recorded Investment	7,020	7,418
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	2,815	2,315
Average Recorded Investment	4,925	7,668
Interest Income Recognized	19	277
Impaired financing receivable with allowance | Commercial Portfolio Segment | Collateralized
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	126
Interest Income Recognized	0	14
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Health care
Loans
Unpaid Principal Balance	5,394	0
Recorded Investment	5,394	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	2,979	0
Average Recorded Investment	1,083	0
Interest Income Recognized	28	0
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Industrial
Loans
Unpaid Principal Balance	3,433	8,339
Recorded Investment	3,433	8,317
Partial Charge-offs	0	22
Allowance for Loan Losses Allocated	1,497	2,669
Average Recorded Investment	2,917	3,215
Interest Income Recognized	4	171
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Multifamily
Loans
Unpaid Principal Balance	0	568
Recorded Investment	0	568
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	320
Average Recorded Investment	0	426
Interest Income Recognized	0	0
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Retail
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	1,345
Interest Income Recognized	0	28
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Office
Loans
Unpaid Principal Balance	0	2,293
Recorded Investment	0	2,277
Partial Charge-offs	0	16
Allowance for Loan Losses Allocated	0	752
Average Recorded Investment	0	636
Interest Income Recognized	0	4
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Other
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	29
Interest Income Recognized	0	0
Impaired financing receivable with allowance | Commercial Real Estate Portfolio Segment | Construction real estate
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired financing receivable with allowance | Consumer Portfolio Segment | Real estate
Loans
Unpaid Principal Balance	21,766	21,380
Recorded Investment	19,313	19,014
Partial Charge-offs	2,453	2,366
Allowance for Loan Losses Allocated	1,996	2,158
Average Recorded Investment	19,311	17,616
Interest Income Recognized	1	25
Impaired financing receivable with allowance | Consumer Portfolio Segment | Indirect vehicle
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired financing receivable with allowance | Consumer Portfolio Segment | Home equity
Loans
Unpaid Principal Balance	32,136	30,762
Recorded Investment	29,661	28,286
Partial Charge-offs	2,475	2,476
Allowance for Loan Losses Allocated	1,937	2,200
Average Recorded Investment	29,681	27,982
Interest Income Recognized	10	54
Impaired financing receivable with allowance | Consumer Portfolio Segment | Other consumer
Loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-offs	0	0
Allowance for Loan Losses Allocated	0	0
Average Recorded Investment	0	0
Interest Income Recognized	$ 0	$ 0

Loans - Loans That Have Been Re

Loans - Loans That Have Been Restructured (Details)	3 Months Ended
	Mar. 31, 2018USD ($)loan	Mar. 31, 2017USD ($)loan
Restructured loans
Redefaulted loans	$ 0
Period past due of redefaulted loans	90 days
Performing
Restructured loans
Number of Loans | loan	1	4
Pre-Modification Recorded Investment	$ 88,000	$ 442,000
Post-Modification Recorded Investment	88,000	442,000
Charge-offs and Specific Reserves	$ 9,000	$ 52,000
Performing | Consumer Portfolio Segment | Real estate
Restructured loans
Number of Loans | loan	1	3
Pre-Modification Recorded Investment	$ 88,000	$ 409,000
Post-Modification Recorded Investment	88,000	409,000
Charge-offs and Specific Reserves	$ 9,000	$ 49,000
Performing | Consumer Portfolio Segment | Home equity
Restructured loans
Number of Loans | loan		1
Pre-Modification Recorded Investment		$ 33,000
Post-Modification Recorded Investment		33,000
Charge-offs and Specific Reserves		$ 3,000
Non-performing
Restructured loans
Number of Loans | loan	22	12
Pre-Modification Recorded Investment	$ 1,707,000	$ 1,277,000
Post-Modification Recorded Investment	1,707,000	1,277,000
Charge-offs and Specific Reserves	$ 797,000	$ 158,000
Non-performing | Consumer Portfolio Segment | Real estate
Restructured loans
Number of Loans | loan	8	9
Pre-Modification Recorded Investment	$ 1,506,000	$ 1,257,000
Post-Modification Recorded Investment	1,506,000	1,257,000
Charge-offs and Specific Reserves	$ 786,000	$ 154,000
Non-performing | Consumer Portfolio Segment | Indirect vehicle
Restructured loans
Number of Loans | loan	11	3
Pre-Modification Recorded Investment	$ 67,000	$ 20,000
Post-Modification Recorded Investment	67,000	20,000
Charge-offs and Specific Reserves	$ 2,000	$ 4,000
Non-performing | Consumer Portfolio Segment | Home equity
Restructured loans
Number of Loans | loan	3
Pre-Modification Recorded Investment	$ 134,000
Post-Modification Recorded Investment	134,000
Charge-offs and Specific Reserves	$ 9,000

Loans - Troubled Debt Restructu

Loans - Troubled Debt Restructuring Activity (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Performing
Financing Receivable, Modifications, Post Modification Recorded Investment [Roll Forward]
Beginning balance	$ 28,554
Additions	88
Charge-offs	0
Principal payments, net	(1,471)
Removals	(77)
Transfer to other real estate owned	0
Transfers in	1,962
Transfers out	(465)
Ending balance	28,591
Non-performing
Financing Receivable, Modifications, Post Modification Recorded Investment [Roll Forward]
Beginning balance	30,836
Additions	1,707
Charge-offs	(20)
Principal payments, net	(1,660)
Removals	(852)
Transfer to other real estate owned	0
Transfers in	465
Transfers out	(1,962)
Ending balance	$ 28,514

Loans - Financing Receivable Mo

Loans - Financing Receivable Modifications and Restructuring (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	$ 1,795
Extended Maturity, Amortization and Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	1,256
Extended Maturity and/or Amortization
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	386
Delay in Payments and/or Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	153
Consumer Portfolio Segment | Residential real estate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	1,594
Consumer Portfolio Segment | Residential real estate | Extended Maturity, Amortization and Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	1,256
Consumer Portfolio Segment | Residential real estate | Extended Maturity and/or Amortization
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	252
Consumer Portfolio Segment | Residential real estate | Delay in Payments and/or Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	86
Consumer Portfolio Segment | Indirect vehicle
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	67
Consumer Portfolio Segment | Indirect vehicle | Extended Maturity, Amortization and Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	0
Consumer Portfolio Segment | Indirect vehicle | Extended Maturity and/or Amortization
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	0
Consumer Portfolio Segment | Indirect vehicle | Delay in Payments and/or Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	67
Consumer Portfolio Segment | Home equity
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	134
Consumer Portfolio Segment | Home equity | Extended Maturity, Amortization and Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	0
Consumer Portfolio Segment | Home equity | Extended Maturity and/or Amortization
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	134
Consumer Portfolio Segment | Home equity | Delay in Payments and/or Reduction of Interest Rate
Activity in the allowance for loan losses, balance in allowance for loan losses and recorded investment in loans by portfolio segment and based on impairment method
Post-modification recorded investment	$ 0

Loans - Allowance for Credit Lo

Loans - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Allowance for credit losses:
Beginning balance	$ 157,710
Ending balance	161,712
Unfunded Commitments
Allowance for unfunded credit commitments, Beginning balance	1,698	$ 2,476
Allowance for unfunded commitments, Charge-Offs	0	0
Allowance for unfunded commitments, Recoveries	0	0
Allowance for unfunded commitments, Provision	(20)	(148)
Allowance for unfunded credit commitments, Ending balance	1,678	2,328
Allowance for credit losses
Allowance for credit losses, Beginning balance	159,408	141,842
Allowance for loan losses and unfunded commitments charge offs	6,818	3,373
Allowance for loan losses and unfunded commitments recoveries	3,292	4,295
Allowance for loan losses and unfunded commitments provision	7,508	3,734
Allowance for credit losses, Ending balance	163,390	146,498
Ending allowance balance attributable to loans:
Individually evaluated for impairment, Unfunded commitments	563	541
Individually evaluated for impairment, Total	11,787	6,639
Collectively evaluated for impairment, Unfunded commitments	1,115	1,787
Collectively evaluated for impairment, Total	150,669	139,530
Acquired and accounted for under ASC 310-30	934	329
Acquired and accounted for under ASC 310-30, Unfunded commitments	0	0
Loans:
Individually evaluated for impairment	77,246	70,451
Individually evaluated for impairment, Unfunded commitments	0	0
Collectively evaluated for impairment	13,747,744	12,719,216
Collectively evaluated for impairment, Unfunded commitments	0	0
Acquired and accounted for under ASC 310-30	109,990	168,814
Acquired and accounted for under ASC 310-30, Unfunded commitments	0	0
Total loans	13,934,980	12,958,481	$ 13,966,062
Total loans, Unfunded commitments	0	0
Commercial Portfolio Segment
Allowance for credit losses:
Beginning balance	46,267	44,661
Charge-offs	1,402	168
Recoveries	337	1,510
Provision	349	(5,313)
Ending balance	45,551	40,690
Ending allowance balance attributable to loans:
Individually evaluated for impairment	2,815	986
Collectively evaluated for impairment	42,662	39,545
Acquired and accounted for under ASC 310-30	74	159
Loans:
Individually evaluated for impairment	12,533	15,214
Collectively evaluated for impairment	4,778,270	4,348,908
Acquired and accounted for under ASC 310-30	10,877	24,768
Total loans	4,801,680	4,388,890
Commercial Portfolio Segment | Collateralized
Allowance for credit losses:
Beginning balance	13,007	12,238
Charge-offs	0
Recoveries	251	463
Provision	(265)	(558)
Ending balance	12,993	12,143
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	12,993	12,143
Acquired and accounted for under ASC 310-30		0
Loans:
Individually evaluated for impairment	0	729
Collectively evaluated for impairment	2,095,189	2,007,872
Acquired and accounted for under ASC 310-30	0	0
Total loans	2,095,189	2,008,601
Commercial Real Estate Portfolio Segment | Commercial real estate
Allowance for credit losses:
Beginning balance	63,429	51,807
Charge-offs	2,476	1,085
Recoveries	762	518
Provision	4,083	6,980
Ending balance	65,798	58,220
Ending allowance balance attributable to loans:
Individually evaluated for impairment	4,476	286
Collectively evaluated for impairment	60,497	57,799
Acquired and accounted for under ASC 310-30	825	135
Loans:
Individually evaluated for impairment	12,136	10,160
Collectively evaluated for impairment	4,080,909	3,724,011
Acquired and accounted for under ASC 310-30	24,648	46,683
Total loans	4,117,693	3,780,854
Commercial Real Estate Portfolio Segment | Construction real estate
Allowance for credit losses:
Beginning balance	15,501	14,758
Charge-offs	0
Recoveries	393	112
Provision	3,909	(11)
Ending balance	19,803	14,859
Ending allowance balance attributable to loans:
Individually evaluated for impairment		0
Collectively evaluated for impairment	19,768	14,824
Acquired and accounted for under ASC 310-30	35	35
Loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	479,638	554,942
Acquired and accounted for under ASC 310-30	4,980	5,624
Total loans	484,618	560,566
Consumer Portfolio Segment | Residential real estate
Allowance for credit losses:
Beginning balance	7,012	5,971
Charge-offs	701	90
Recoveries	70	528
Provision	(5)	1,722
Ending balance	6,376	8,131
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,996	2,192
Collectively evaluated for impairment	4,380	5,939
Acquired and accounted for under ASC 310-30		0
Loans:
Individually evaluated for impairment	22,707	15,803
Collectively evaluated for impairment	1,369,193	1,211,415
Acquired and accounted for under ASC 310-30	57,633	77,332
Total loans	1,449,533	1,304,550
Consumer Portfolio Segment | Indirect vehicle
Allowance for credit losses:
Beginning balance	4,728	3,421
Charge-offs	1,824	1,411
Recoveries	1,179	652
Provision	267	962
Ending balance	4,350	3,624
Ending allowance balance attributable to loans:
Individually evaluated for impairment		0
Collectively evaluated for impairment	4,350	3,624
Acquired and accounted for under ASC 310-30		0
Loans:
Individually evaluated for impairment	209	108
Collectively evaluated for impairment	692,433	573,684
Acquired and accounted for under ASC 310-30	0	0
Total loans	692,642	573,792
Consumer Portfolio Segment | Home equity
Allowance for credit losses:
Beginning balance	5,296	5,469
Charge-offs	64	173
Recoveries	70	283
Provision	(956)	(267)
Ending balance	4,346	5,312
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,937	2,634
Collectively evaluated for impairment	2,409	2,678
Acquired and accounted for under ASC 310-30		0
Loans:
Individually evaluated for impairment	29,661	28,437
Collectively evaluated for impairment	173,259	218,368
Acquired and accounted for under ASC 310-30	10,483	12,382
Total loans	213,403	259,187
Consumer Portfolio Segment | Other
Allowance for credit losses:
Beginning balance	2,470	1,041
Charge-offs	351	446
Recoveries	230	229
Provision	146	367
Ending balance	2,495	1,191
Ending allowance balance attributable to loans:
Individually evaluated for impairment		0
Collectively evaluated for impairment	2,495	1,191
Acquired and accounted for under ASC 310-30		0
Loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	78,853	80,016
Acquired and accounted for under ASC 310-30	1,369	2,025
Total loans	$ 80,222	$ 82,041

Loans - Changes in the Accretab

Loans - Changes in the Accretable Yield (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Changes in the accretable yield for purchased credit-impaired loans
Balance at beginning of period	$ 12,069	$ 16,050
Purchases	0	43
Accretion	(2,411)	(2,188)
Other	609	1,006
Balance at end of period	$ 10,267	$ 14,911

Loans - Carrying Amount of Loan

Loans - Carrying Amount of Loans Acquired (Details) $ in Thousands	Mar. 31, 2018USD ($)
Loans
Non covered loans	$ 1,247,201
Total acquired	1,261,650
Purchased Credit-Impaired Loans
Loans
Non covered loans	46,067
Total acquired	60,516
Purchased Non-Credit-Impaired Loans
Loans
Non covered loans	1,201,134
Total acquired	1,201,134
Other Loans | Purchased Credit-Impaired Loans | Ginnie Mae
Loans
Consumer related purchased credit-impaired loans	49,500
Consumer Portfolio Segment | Consumer related
Loans
Covered loans	14,449
Non covered loans	258,222
Consumer Portfolio Segment | Consumer related | Purchased Credit-Impaired Loans
Loans
Covered loans	14,449
Non covered loans	5,562
Consumer Portfolio Segment | Consumer related | Purchased Non-Credit-Impaired Loans
Loans
Covered loans	0
Non covered loans	252,660
Commercial Portfolio Segment
Loans
Non covered loans	220,947
Commercial Portfolio Segment | Purchased Credit-Impaired Loans
Loans
Non covered loans	10,877
Commercial Portfolio Segment | Purchased Non-Credit-Impaired Loans
Loans
Non covered loans	210,070
Commercial Portfolio Segment | Collateralized
Loans
Non covered loans	30,534
Commercial Portfolio Segment | Collateralized | Purchased Credit-Impaired Loans
Loans
Non covered loans	0
Commercial Portfolio Segment | Collateralized | Purchased Non-Credit-Impaired Loans
Loans
Non covered loans	30,534
Commercial Real Estate Portfolio Segment | Real estate
Loans
Non covered loans	727,775
Commercial Real Estate Portfolio Segment | Real estate | Purchased Credit-Impaired Loans
Loans
Non covered loans	24,648
Commercial Real Estate Portfolio Segment | Real estate | Purchased Non-Credit-Impaired Loans
Loans
Non covered loans	703,127
Commercial Real Estate Portfolio Segment | Construction real estate
Loans
Non covered loans	9,723
Commercial Real Estate Portfolio Segment | Construction real estate | Purchased Credit-Impaired Loans
Loans
Non covered loans	4,980
Commercial Real Estate Portfolio Segment | Construction real estate | Purchased Non-Credit-Impaired Loans
Loans
Non covered loans	$ 4,743

Goodwill and Intangibles - Addi

Goodwill and Intangibles - Additional Information (Details)	3 Months Ended
	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)segment	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Goodwill [Line Items]
Number of operating segments | segment		3
Goodwill		$ 1,003,548,000		$ 1,003,548,000
Impairment loss		$ 0	$ 0
Weighted average amortization period (in years)		12 years
Mortgage Banking
Goodwill [Line Items]
Goodwill		$ 3,623,000
Subsequent Event
Goodwill [Line Items]
Impairment loss	$ 3,600,000

Goodwill and Intangibles - Chan

Goodwill and Intangibles - Changes In Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 1,003,548	$ 1,003,548
Banking
Goodwill [Line Items]
Goodwill	959,285
Leasing
Goodwill [Line Items]
Goodwill	40,640
Mortgage Banking
Goodwill [Line Items]
Goodwill	$ 3,623

Goodwill and Intangibles - Ch59

Goodwill and Intangibles - Changes in Core Deposit and Client Relationship Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018
Changes in the carrying amount of core deposit and client relationship intangibles
Balance at beginning of period	$ 54,766
Amortization expense	(1,902)	$ (2,090)
Balance at end of period	52,864
Gross carrying amount			$ 112,820
Accumulated amortization			(59,956)
Net book value	$ 54,766		$ 52,864

Goodwill and Intangibles - Esti

Goodwill and Intangibles - Estimated Future Amortization Expense (Details) $ in Thousands	Mar. 31, 2018USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 5,549
2,019	5,674
2,020	5,022
2,021	4,790
2,022	3,806
Thereafter	28,023
Total estimated future amortization expense	$ 52,864

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Demand deposit accounts, noninterest bearing	$ 6,385,149	$ 6,381,512
NOW, money market, and interest bearing deposits	4,858,506	4,954,765
Savings accounts	1,229,968	1,167,810
Certificates of deposit, $250,000 or more	1,519,552	1,506,071
Other certificates of deposit	977,418	948,220
Total deposits	14,970,593	14,958,378
Brokered deposits	$ 1,100,000	$ 1,100,000

Short-Term Borrowings - Schedul

Short-Term Borrowings - Schedule of Short-Term Borrowings (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Short-term borrowings
Weighted Average Interest Rate	1.36%	1.03%
Amount	$ 717,679,000	$ 861,039,000
Customer repurchase agreements
Short-term borrowings
Weighted Average Interest Rate	0.38%	0.27%
Amount	$ 225,962,000	$ 232,789,000
Federal Home Loan Bank advances
Short-term borrowings
Weighted Average Interest Rate	1.85%	1.31%
Amount	$ 365,000,000	$ 625,000,000
Federal funds purchased
Short-term borrowings
Weighted Average Interest Rate	1.69%	1.26%
Amount	$ 126,717,000	$ 3,250,000
Line of credit
Short-term borrowings
Weighted Average Interest Rate	0.00%	0.00%
Amount	$ 0	$ 0

Short-Term Borrowings - Additio

Short-Term Borrowings - Additional Information (Details) - USD ($)	Aug. 24, 2016	Dec. 18, 2015	Mar. 31, 2018	Dec. 31, 2017
Short-term borrowings
Fixed interest rate Federal Home Loan Bank advances			$ 365,000,000	$ 625,000,000
Short-term borrowings			717,679,000	861,039,000
London Interbank Offered Rate (LIBOR)
Short-term borrowings
Basis spread on variable rate	1.75%
Federal Home Loan Bank advances
Short-term borrowings
Short-term borrowings			365,000,000	625,000,000
Line of credit
Short-term borrowings
Line of credit facility, maximum borrowing capacity		$ 35,000,000
Short-term borrowings			$ 0	$ 0
Line of credit | London Interbank Offered Rate (LIBOR)
Short-term borrowings
Basis spread on variable rate		1.75%
Minimum | Federal Home Loan Bank advances
Short-term borrowings
Effective interest rate of amounts due within one year			1.35%
Maximum | Federal Home Loan Bank advances
Short-term borrowings
Effective interest rate of amounts due within one year			2.05%

Long-Term Borrowings (Details)

Long-Term Borrowings (Details) - USD ($)	Aug. 24, 2016	Mar. 31, 2018	Dec. 31, 2017
Long-term borrowings
Weighted Average Interest Rate		2.80%	2.97%
Amount		$ 851,221,000	$ 505,158,000
Federal Home Loan Bank advances		$ 591,300,000	$ 231,300,000
London Interbank Offered Rate (LIBOR)
Long-term borrowings
Basis spread on variable rate	1.75%
Federal Home Loan Bank advances
Long-term borrowings
Weighted Average Interest Rate		2.24%	1.73%
Amount		$ 591,266,000	$ 231,317,000
Federal Home Loan Bank advances | Minimum
Long-term borrowings
Interest rate		1.78%
Federal Home Loan Bank advances | Maximum
Long-term borrowings
Interest rate		5.87%
Notes payable
Long-term borrowings
Weighted Average Interest Rate		4.21%	4.14%
Amount		$ 87,017,000	$ 90,807,000
Subordinated notes, net of issuance costs
Long-term borrowings
Weighted Average Interest Rate		4.00%	4.00%
Amount		$ 172,938,000	$ 173,034,000
Unsecured term
Long-term borrowings
Weighted Average Interest Rate		0.00%	3.31%
Amount	$ 16,000,000	$ 0	$ 10,000,000
Quarterly principal payments	$ 1,000,000
Notes payable to banks
Long-term borrowings
Weighted Average Interest Rate		4.36%
Amount		$ 73,100,000	76,300,000
Equipment pledged as collateral		$ 87,500,000	$ 91,900,000
Notes payable to banks | Minimum
Long-term borrowings
Interest rate		2.25%
Notes payable to banks | Maximum
Long-term borrowings
Interest rate		7.40%
Other secured borrowings
Long-term borrowings
Weighted Average Interest Rate		3.44%
Amount		$ 13,900,000

Junior Subordinated Notes Iss65

Junior Subordinated Notes Issued to Capital Trusts (Details) - USD ($) $ in Thousands	Mar. 19, 2018	Aug. 24, 2016	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Junior Subordinated Notes
Principal balance			$ 194,304		$ 211,494
Investment Owned, Balance [Abstract]
Loss on extinguishment of debt			$ 3,136	$ 0
Junior Subordinated Notes | Maximum
Investment Owned, Balance [Abstract]
Period for deferment of payment of interest on notes (in years)			5 years
London Interbank Offered Rate (LIBOR)
Junior Subordinated Notes
Basis spread on variable rate		1.75%
Coal City Capital Trust I | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			1.80%
Face Value			$ 25,000
Coal City Capital Trust I | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 25,774
Basis spread on variable rate			1.80%
MB Financial Capital Trust II | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			1.40%
Face Value			$ 35,000
MB Financial Capital Trust II | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 36,083
Basis spread on variable rate			1.40%
MB Financial Capital Trust III | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			1.50%
Face Value			$ 10,000
MB Financial Capital Trust III | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 10,310
Basis spread on variable rate			1.50%
MB Financial Capital Trust IV | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			1.52%
Face Value			$ 20,000
MB Financial Capital Trust IV | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 20,619
Basis spread on variable rate			1.52%
MB Financial Capital Trust V | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			1.30%
Face Value			$ 30,000
MB Financial Capital Trust V | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 30,928
Basis spread on variable rate			1.30%
MB Financial Capital Trust VI | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			1.30%
Face Value			$ 22,500
MB Financial Capital Trust VI | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 23,196
Basis spread on variable rate			1.30%
FOBB Statutory Trust III | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			2.80%
Face Value			$ 5,000
FOBB Statutory Trust III | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 5,155
Basis spread on variable rate			2.80%
TAYC Capital Trust II
Investment Owned, Balance [Abstract]
Purchase accounting adjustments discount			$ 6,300
TAYC Capital Trust II | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			2.68%
Face Value			$ 40,000
TAYC Capital Trust II | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 41,238
Basis spread on variable rate			2.68%
American Chartered Statutory Trust II | Trust Preferred Securities
Junior Subordinated Notes
Basis spread on variable rate			2.75%
Face Value			$ 10,000
American Chartered Statutory Trust II | Junior Subordinated Notes
Junior Subordinated Notes
Principal balance			$ 10,310
Basis spread on variable rate			2.75%
American Chartered Statutory Trust I and American Chartered Statutory Trust II
Investment Owned, Balance [Abstract]
Purchase accounting adjustments discount			$ 2,700
American Chartered Statutory Trust I | Trust Preferred Securities
Junior Subordinated Notes
Face Value	$ 20,000
Investment Owned, Balance [Abstract]
Loss on extinguishment of debt			$ (3,100)
American Chartered Statutory Trust I | London Interbank Offered Rate (LIBOR) | Junior Subordinated Notes
Junior Subordinated Notes
Basis spread on variable rate	3.60%

Commitments and Contingencies66

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Commitments [Abstract]
Maximum maturity period for letters of credit (in years)	5 years
Increase (decrease) in maximum potential amount of future payments under letters of credit	$ (844)
Dollar amount of letters of credit outstanding	162,400	$ 163,300
Letters of credit issued or renewed	43,400
Capital expenditure commitments outstanding	$ 7,200
State of Illinois | States and political subdivisions
Concentrations of credit risk
Concentration risk	19.00%
Home equity lines
Long-term Purchase Commitment [Line Items]
Dollar amount of line of credit outstanding	$ 198,649	203,922
Other commitments
Long-term Purchase Commitment [Line Items]
Dollar amount of line of credit outstanding	3,965,840	4,073,044
Standby
Long-term Purchase Commitment [Line Items]
Dollar amount of line of credit outstanding	161,752	161,014
Commercial
Long-term Purchase Commitment [Line Items]
Dollar amount of line of credit outstanding	$ 666	$ 2,248

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value On A Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	$ 1,679,011	$ 1,408,326
Loans held for sale	561,549	548,578
Loans	13,824,990	13,846,318
Mortgage servicing rights	291,561	276,279
Derivative financial instruments	38,174	17,540
Derivative financial instruments	19,290	27,947
U.S. Government sponsored agencies and enterprises
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	22,885	23,007
States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	366,906	379,325
Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	1,187,068	852,699
Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	64,161	72,035
Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	37,991	70,197
Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale		11,063
Recurring basis
Financial assets and financial liabilities measured at fair value on a recurring basis
Loans held for sale	561,549	548,578
Loans	39,206	40,531
Assets held in trust for deferred compensation	23,324	21,410
Other liabilities	23,324	21,410
Derivative financial instruments	46,181	40,296
Recurring basis | U.S. Government sponsored agencies and enterprises
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	22,885	23,007
Recurring basis | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	366,906	379,325
Recurring basis | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	1,187,068	852,699
Recurring basis | Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	64,161	72,035
Recurring basis | Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	37,991	70,197
Recurring basis | Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale		11,063
Marketable equity securities	11,124
Recurring basis | Mortgage servicing rights
Financial assets and financial liabilities measured at fair value on a recurring basis
Mortgage servicing rights	291,561	276,279
Recurring basis | Derivative financial instruments
Financial assets and financial liabilities measured at fair value on a recurring basis
Derivative financial instruments	49,005	31,499
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	11,063
Marketable equity securities	11,124
Loans held for sale	0	0
Loans	0	0
Assets held in trust for deferred compensation	23,324	21,410
Derivative financial instruments	1,082	389
Other liabilities	23,324	21,410
Derivative financial instruments	2,130	1,072
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government sponsored agencies and enterprises
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale		11,063
Marketable equity securities	11,124
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage servicing rights
Financial assets and financial liabilities measured at fair value on a recurring basis
Mortgage servicing rights	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivative financial instruments
Financial assets and financial liabilities measured at fair value on a recurring basis
Derivative financial instruments	1,082	389
Recurring basis | Significant Other Observable Inputs (Level 2)
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	1,678,663	1,396,900
Marketable equity securities	0
Loans held for sale	561,549	548,578
Loans	39,206	40,531
Assets held in trust for deferred compensation	0	0
Derivative financial instruments	45,642	29,539
Other liabilities	0	0
Derivative financial instruments	44,051	39,224
Recurring basis | Significant Other Observable Inputs (Level 2) | U.S. Government sponsored agencies and enterprises
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	22,885	23,007
Recurring basis | Significant Other Observable Inputs (Level 2) | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	366,577	378,996
Recurring basis | Significant Other Observable Inputs (Level 2) | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	1,187,049	852,665
Recurring basis | Significant Other Observable Inputs (Level 2) | Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	64,161	72,035
Recurring basis | Significant Other Observable Inputs (Level 2) | Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	37,991	70,197
Recurring basis | Significant Other Observable Inputs (Level 2) | Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale		0
Marketable equity securities	0
Recurring basis | Significant Other Observable Inputs (Level 2) | Mortgage servicing rights
Financial assets and financial liabilities measured at fair value on a recurring basis
Mortgage servicing rights	0	0
Recurring basis | Significant Other Observable Inputs (Level 2) | Derivative financial instruments
Financial assets and financial liabilities measured at fair value on a recurring basis
Derivative financial instruments	45,642	29,539
Recurring basis | Significant Unobservable Inputs (Level 3)
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	348	363
Marketable equity securities	0
Loans held for sale	0	0
Loans	0	0
Assets held in trust for deferred compensation	0	0
Derivative financial instruments	2,281	1,571
Other liabilities	0	0
Derivative financial instruments	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | U.S. Government sponsored agencies and enterprises
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	329	329
Recurring basis | Significant Unobservable Inputs (Level 3) | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	19	34
Recurring basis | Significant Unobservable Inputs (Level 3) | Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale		0
Marketable equity securities	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Mortgage servicing rights
Financial assets and financial liabilities measured at fair value on a recurring basis
Mortgage servicing rights	291,561	276,279
Recurring basis | Significant Unobservable Inputs (Level 3) | Derivative financial instruments
Financial assets and financial liabilities measured at fair value on a recurring basis
Derivative financial instruments	$ 2,281	$ 1,571

Fair Value Measurements - Unobs

Fair Value Measurements - Unobservable Inputs Used In Fair Value Measurement (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	$ 1,679,011,000	$ 1,408,326,000
Mortgage servicing rights	291,561,000	276,279,000
Derivative financial instruments	38,174,000	17,540,000
States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	366,906,000	379,325,000
Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	1,187,068,000	852,699,000
Recurring basis | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	366,906,000	379,325,000
Recurring basis | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	1,187,068,000	852,699,000
Recurring basis | Mortgage servicing rights
Financial assets and financial liabilities measured at fair value on a recurring basis
Mortgage servicing rights	291,561,000	276,279,000
Recurring basis | Derivative financial instruments
Financial assets and financial liabilities measured at fair value on a recurring basis
Derivative financial instruments	49,005,000	31,499,000
Significant Unobservable Inputs (Level 3) | Recurring basis
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	348,000	363,000
Derivative financial instruments	2,281,000	1,571,000
Significant Unobservable Inputs (Level 3) | Recurring basis | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	$ 329,000	$ 329,000
Significant Unobservable Inputs (Level 3) | Recurring basis | States and political subdivisions | Minimum
Financial assets and financial liabilities measured at fair value on a recurring basis
Credit assumption (as a percent)	40.00%	40.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | States and political subdivisions | Maximum
Financial assets and financial liabilities measured at fair value on a recurring basis
Credit assumption (as a percent)	45.00%	45.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	$ 19,000	$ 34,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Residential mortgage-backed securities | Minimum
Financial assets and financial liabilities measured at fair value on a recurring basis
Constant prepayment rates (as a percent)	1.00%	1.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | Residential mortgage-backed securities | Maximum
Financial assets and financial liabilities measured at fair value on a recurring basis
Constant prepayment rates (as a percent)	3.00%	3.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | Mortgage servicing rights
Financial assets and financial liabilities measured at fair value on a recurring basis
Mortgage servicing rights	$ 291,561,000	$ 276,279,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Mortgage servicing rights | Minimum
Financial assets and financial liabilities measured at fair value on a recurring basis
Constant prepayment rates (as a percent)	6.35%	6.70%
Discount rate	9.53%	9.53%
Maturity (months)	325 months	324 months
Delinquencies	2.05%	2.42%
Costs to service	$ 67	$ 67
Additive delinquent costs to service	$ 175	$ 175
Significant Unobservable Inputs (Level 3) | Recurring basis | Mortgage servicing rights | Maximum
Financial assets and financial liabilities measured at fair value on a recurring basis
Constant prepayment rates (as a percent)	6.84%	7.80%
Discount rate	11.06%	11.06%
Maturity (months)	358 months	358 months
Delinquencies	4.78%	5.30%
Costs to service	$ 227	$ 227
Additive delinquent costs to service	1,000	1,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Derivative financial instruments
Financial assets and financial liabilities measured at fair value on a recurring basis
Derivative financial instruments	$ 2,281,000	$ 1,571,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Derivative financial instruments | Minimum
Financial assets and financial liabilities measured at fair value on a recurring basis
Expected closing ratio	70.00%	70.00%
Expected delivery price	0.9312%	0.9738%
Significant Unobservable Inputs (Level 3) | Recurring basis | Derivative financial instruments | Maximum
Financial assets and financial liabilities measured at fair value on a recurring basis
Expected closing ratio	95.00%	95.00%
Expected delivery price	1.0662%	1.0687%

Fair Value Measurements - Assum

Fair Value Measurements - Assumptions Used In Measuring Fair Value of Mortgage Servicing Rights (Details) - Mortgage servicing rights	3 Months Ended
	Mar. 31, 2018USD ($)
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Impact on fair value of 10% adverse change, CPR	$ (8,500,000)
Impact on fair value of 20% adverse change, CPR	(16,583,000)
Impact on fair value of 10% adverse change, discount rate	(12,400,000)
Impact on fair value of 20% adverse change, discount rate	(23,803,000)
Impact on fair value of 10% adverse change, delinquency rate	(3,960,000)
Impact on fair value of 20% adverse change, delinquency rate	(6,298,000)
Impact on fair value of 10% adverse change, costs to service	(5,454,000)
Impact on fair value of 20% adverse change, costs to service	$ (10,908,000)
Weighted average
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted average CPR	6.52%
Weighted average discount rate	9.82%
Weighted average delinquency rate	4.56%
Weighted average costs to service	$ 91.25

Fair Value Measurements - Level

Fair Value Measurements - Level 3 Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Investment Securities
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance, beginning of period	$ 363	$ 544
Purchases	0	0
Originations	0	0
Included in earnings	0	0
Principal payments	(15)	(35)
Sales	0	0
Balance, ending of period	348	509
Mortgage Servicing Rights
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance, beginning of period	276,279	238,011
Purchases	67	496
Originations	12,340	15,651
Included in earnings	2,875	(2,660)
Principal payments	0	0
Sales	0	0
Balance, ending of period	291,561	251,498
Derivatives
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance, beginning of period	1,571	3,160
Purchases	0	0
Originations	0	0
Included in earnings	710	2,451
Principal payments	0	0
Sales	0	0
Balance, ending of period	$ 2,281	$ 5,611

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair value assumption, allowance for impaired real estate loans percentage	100.00%
Maximum maturity period of short-term borrowings where carrying value approximates fair value (in days)	90 days
Minimum maturity period of short-term borrowings where fair value is based on discounted value of contractual cash flows (in days)	90 days

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Details) - Nonrecurring basis - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial Assets:
Impaired loans	$ 58,717	$ 60,569
Foreclosed assets	15,374	$ 15,113
Maximum
Financial Assets:
Appraisal adjustment foreclosed assets (as a percent)		10.00%
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Impaired loans	0	$ 0
Foreclosed assets	0	0
Significant Other Observable Inputs (Level 2)
Financial Assets:
Impaired loans	0	0
Foreclosed assets	0	0
Significant Unobservable Inputs (Level 3)
Financial Assets:
Impaired loans	58,717	60,569
Foreclosed assets	$ 15,374	$ 15,113
Significant Unobservable Inputs (Level 3) | Minimum
Financial Assets:
Appraisal adjustment impaired loans (as a percent)	5.00%	5.00%
Appraisal adjustment foreclosed assets (as a percent)	5.00%	5.00%
Significant Unobservable Inputs (Level 3) | Maximum
Financial Assets:
Appraisal adjustment impaired loans (as a percent)	10.00%	10.00%
Appraisal adjustment foreclosed assets (as a percent)	10.00%

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial Assets:
Cash and due from banks	$ 332,234	$ 397,880
Interest earning deposits with banks	50,624	181,341
Investment securities available for sale	1,679,011	1,408,326
Investment securities held to maturity	950,806	992,455
Non-marketable securities - FHLB and FRB stock	118,955	114,111
Loans held for sale	561,549	548,578
Derivative financial instruments	38,174	17,540
Financial Liabilities:
Non-interest bearing deposits	6,385,149	6,381,512
Interest bearing deposits	8,585,444	8,576,866
Short-term borrowings	717,679	861,039
Junior subordinated notes issued to capital trusts	194,304	211,494
Derivative financial instruments	19,290	27,947
Recurring basis
Financial Assets:
Loans held for sale	561,549	548,578
Financial Liabilities:
Derivative financial instruments	46,181	40,296
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Cash and due from banks	332,234	397,880
Interest earning deposits with banks	50,624	181,341
Investment securities available for sale	0	11,063
Investment securities held to maturity	0	0
Marketable equity securities	11,124
Non-marketable securities - FHLB and FRB stock	0	0
Loans held for sale	0	0
Loans, net	0	0
Accrued interest receivable	65,445	63,589
Derivative financial instruments	1,082	389
Financial Liabilities:
Non-interest bearing deposits	6,385,149	6,381,512
Interest bearing deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Junior subordinated notes issued to capital trusts	0	0
Accrued interest payable	8,352	6,458
Derivative financial instruments	2,130	1,072
Recurring basis | Significant Other Observable Inputs (Level 2)
Financial Assets:
Cash and due from banks	0	0
Interest earning deposits with banks	0	0
Investment securities available for sale	1,678,663	1,396,900
Investment securities held to maturity	950,806	992,455
Marketable equity securities	0
Non-marketable securities - FHLB and FRB stock	0	0
Loans held for sale	561,549	548,578
Loans, net	39,206	40,531
Accrued interest receivable	0	0
Derivative financial instruments	45,642	29,539
Financial Liabilities:
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Junior subordinated notes issued to capital trusts	0	0
Accrued interest payable	0	0
Derivative financial instruments	44,051	39,224
Recurring basis | Significant Unobservable Inputs (Level 3)
Financial Assets:
Cash and due from banks	0	0
Interest earning deposits with banks	0	0
Investment securities available for sale	348	363
Investment securities held to maturity	0	0
Marketable equity securities	0
Non-marketable securities - FHLB and FRB stock	118,955	114,111
Loans held for sale	0	0
Loans, net	13,834,172	13,947,861
Accrued interest receivable	0	0
Derivative financial instruments	2,281	1,571
Financial Liabilities:
Non-interest bearing deposits	0	0
Interest bearing deposits	8,574,742	8,569,368
Short-term borrowings	717,400	860,676
Long-term borrowings	855,337	513,725
Junior subordinated notes issued to capital trusts	156,323	170,965
Accrued interest payable	0	0
Derivative financial instruments	0	0
Carrying Amount
Financial Assets:
Cash and due from banks	332,234	397,880
Interest earning deposits with banks	50,624	181,341
Investment securities available for sale	1,679,011	1,408,326
Investment securities held to maturity	933,319	959,082
Marketable equity securities	11,124
Non-marketable securities - FHLB and FRB stock	118,955	114,111
Loans held for sale	561,549	548,578
Loans, net	13,773,268	13,808,352
Accrued interest receivable	65,445	63,589
Derivative financial instruments	49,005	31,499
Financial Liabilities:
Non-interest bearing deposits	6,385,149	6,381,512
Interest bearing deposits	8,585,444	8,576,866
Short-term borrowings	717,679	861,039
Long-term borrowings	851,221	505,158
Junior subordinated notes issued to capital trusts	194,304	211,494
Accrued interest payable	8,352	6,458
Derivative financial instruments	46,181	40,296
Estimated Fair Value
Financial Assets:
Cash and due from banks	332,234	397,880
Interest earning deposits with banks	50,624	181,341
Investment securities available for sale	1,679,011	1,408,326
Investment securities held to maturity	950,806	992,455
Marketable equity securities	11,124
Non-marketable securities - FHLB and FRB stock	118,955	114,111
Loans held for sale	561,549	548,578
Loans, net	13,873,378	13,988,392
Accrued interest receivable	65,445	63,589
Derivative financial instruments	49,005	31,499
Financial Liabilities:
Non-interest bearing deposits	6,385,149	6,381,512
Interest bearing deposits	8,574,742	8,569,368
Short-term borrowings	717,400	860,676
Long-term borrowings	855,337	513,725
Junior subordinated notes issued to capital trusts	156,323	170,965
Accrued interest payable	8,352	6,458
Derivative financial instruments	$ 46,181	$ 40,296

Stock Incentive Plans - Impact

Stock Incentive Plans - Impact of Share-Based Payment Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total compensation expense for share-based payment plans during the period	$ 4,451	$ 4,481
Amount of related income tax benefit recognized in income	$ 1,354	$ 4,422

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Details) - USD ($) $ in Millions	Aug. 18, 2014	May 28, 2014	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-based compensation
Grants beyond threshold limit count numerator (in shares)		2
Omnibus Incentive Plan
Stock-based compensation
Additional number of share authorized (in shares)		3,100,000
Total number of shares authorized (in shares)		11,400,000
Percentage of shares authorized for issuance		10.00%
Vesting period		3 years
Shares available for future grant (in shares)			2,099,458
Unrecognized compensation cost related to nonvested share-based compensation			$ 35.8
Period for recognition			3 years
Omnibus Incentive Plan | Taylor Capital Group, Inc.
Stock-based compensation
Total number of shares authorized (in shares)	13,800,000
Increase in amount of shares authorized (in shares)	2,400,000
Stock options
Stock-based compensation
Award requisite service period			4 years
Expiration term of options			10 years
Intrinsic value of options exercised			$ 1.6	$ 2.9
Stock options | Director
Stock-based compensation
Vesting period			5 years
Maximum percentage of directors fees with option to be received in equity based incentive awards			70.00%
Period of restriction for sale of shares vested			6 months
Restricted shares
Stock-based compensation
Intrinsic value of restricted shares that vested			$ 12.5	$ 15.3
Restricted shares | Minimum
Stock-based compensation
Vesting period			2 years
Restricted shares | Maximum
Stock-based compensation
Vesting period			4 years
Restricted stock | Director
Stock-based compensation
Vesting period			1 year
Maximum percentage of directors fees with option to be received in equity based incentive awards			100.00%
Performance-based restricted stock units
Stock-based compensation
Vesting period			3 years
Restricted stock issued (in shares)			71,567		65,476	80,780	71,560
Percentage of shares earned to number of units issued			0.00%
Performance based restricted units performance period			3 years
Share based compensation restricted stock units multiplier			100.00%
Performance-based restricted stock units | Minimum
Stock-based compensation
Percentage of shares earned to number of units issued			0.00%
Performance-based restricted stock units | Maximum
Stock-based compensation
Percentage of shares earned to number of units issued			175.00%

Stock Incentive Plans - Summary

Stock Incentive Plans - Summary of Impact of Share-Based Payment Plans (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Number of Options
Outstanding, beginning balance (in shares)	1,721,978
Granted (in shares)	156,687
Exercised (in shares)	(95,749)
Expired (in shares)	(1,092)
Forfeited or cancelled (in shares)	(4,764)
Outstanding, ending balance (in shares)	1,777,060	1,721,978
Options exercisable (in shares)	1,265,177
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 29.10
Granted (in dollars per share)	41
Exercised (in dollars per share)	27.24
Expired (in dollars per share)	39.28
Forfeited or cancelled (in dollars per share)	30.22
Outstanding, ending balance (in dollars per share)	30.24	$ 29.10
Options exercisable (in dollars per share)	$ 27.71
Weighted Average Remaining Contractual Term (In Years)
Outstanding, balance (in years)	5 years 6 months 10 days	5 years 2 months 10 days
Options exercisable (in years)	4 years 3 months 24 days
Aggregate Intrinsic Value (in thousands)
Options outstanding	$ 19,173
Options exercisable	$ 16,468

Stock Incentive Plans - Assumpt

Stock Incentive Plans - Assumptions Used For Options Granted (Details) - Stock options	3 Months Ended
	Mar. 31, 2018$ / shares
Fair value assumptions
Risk-free interest rate	2.80%
Expected volatility of Company’s stock	25.98%
Expected dividend yield	2.06%
Expected life of options	5 years 10 months 20 days
Weighted average fair value per option of options granted during the year (in dollars per share)	$ 9.61

Stock Incentive Plans - Changes

Stock Incentive Plans - Changes in Restricted Shares and Units (Details) - Restricted shares	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Number of Shares and Units
Shares and units outstanding, beginning balance (in shares) | shares	973,201
Granted (in shares) | shares	414,012
Vested (in shares) | shares	(297,033)
Forfeited or cancelled (in shares) | shares	(80,035)
Shares and units outstanding, ending balance (in shares) | shares	1,010,145
Weighted Average Grant Date Fair Value
Shares and units outstanding, beginning balance (in dollars per share) | $ / shares	$ 37.03
Granted (in dollars per share) | $ / shares	41.44
Vested (in dollars per share) | $ / shares	34.91
Forfeited or cancelled (in dollars per share) | $ / shares	34.38
Shares and units outstanding, ending balance (in dollars per share) | $ / shares	$ 39.67

Derivative Financial Instrume79

Derivative Financial Instruments - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Net amount payable under interest rate swap	$ 1	$ 1
Interest rate swap credit risk exposure	4,800
Derivative liability, notional amount	2,983,575	$ 3,591,647
Commercial loan interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount	$ 45

Derivative Financial Instrume80

Derivative Financial Instruments - Summary of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Derivative [Line Items]
Asset Derivatives, Notional Amount	$ 3,368,643		$ 3,142,730
Asset Derivatives, Estimated Fair Value	49,005		31,499
Liability Derivatives, Notional Amount	2,983,575		3,591,647
Liability Derivatives, Estimated Fair Value	(46,181)		(40,296)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	1,910	$ (7,550)
Derivative instruments designated as hedges of fair value | Interest rate swap contracts
Derivative [Line Items]
Asset Derivatives, Notional Amount	0		0
Asset Derivatives, Estimated Fair Value	0		0
Liability Derivatives, Notional Amount	45		58
Liability Derivatives, Estimated Fair Value	(1)		(1)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	0	1
Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	3,368,643		3,142,730
Asset Derivatives, Estimated Fair Value	49,005		31,499
Liability Derivatives, Notional Amount	2,983,530		3,591,589
Liability Derivatives, Estimated Fair Value	(46,180)		(40,295)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	1,910	(7,551)
Stand-alone derivative instruments | Interest rate swap contracts
Derivative [Line Items]
Asset Derivatives, Notional Amount	1,647,481		1,563,109
Asset Derivatives, Estimated Fair Value	28,308		21,217
Liability Derivatives, Notional Amount	1,647,481		1,563,109
Liability Derivatives, Estimated Fair Value	(28,308)		(21,217)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	1,715	1,849
Stand-alone derivative instruments | Interest rate swap contracts | Mortgage Banking
Derivative [Line Items]
Asset Derivatives, Notional Amount	275,000		458,000
Asset Derivatives, Estimated Fair Value	9,234		4,479
Liability Derivatives, Notional Amount	270,000		1,008,000
Liability Derivatives, Estimated Fair Value	(8,709)		(14,360)
Stand-alone derivative instruments | Interest rate options contracts
Derivative [Line Items]
Asset Derivatives, Notional Amount	402,633		372,927
Asset Derivatives, Estimated Fair Value	3,326		1,887
Liability Derivatives, Notional Amount	402,566		372,927
Liability Derivatives, Estimated Fair Value	(3,326)		(1,887)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	0	0
Stand-alone derivative instruments | Foreign exchange contracts
Derivative [Line Items]
Asset Derivatives, Notional Amount	57,689		40,713
Asset Derivatives, Estimated Fair Value	3,879		1,934
Liability Derivatives, Notional Amount	56,866		34,029
Liability Derivatives, Estimated Fair Value	(3,695)		(1,759)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	43	63
Stand-alone derivative instruments | Spot foreign exchange contracts
Derivative [Line Items]
Asset Derivatives, Notional Amount	503		1,424
Asset Derivatives, Estimated Fair Value	20		23
Liability Derivatives, Notional Amount	117		24
Liability Derivatives, Estimated Fair Value	(12)		0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	733	678
Stand-alone derivative instruments | Interest rate swaptions contracts | Mortgage Banking
Derivative [Line Items]
Asset Derivatives, Notional Amount	290,000		0
Asset Derivatives, Estimated Fair Value	875		0
Liability Derivatives, Notional Amount	0		0
Liability Derivatives, Estimated Fair Value	0		0
Stand-alone derivative instruments | Treasury futures contracts | Mortgage Banking
Derivative [Line Items]
Asset Derivatives, Notional Amount	20,000		28,000
Asset Derivatives, Estimated Fair Value	100		39
Liability Derivatives, Notional Amount	0		30,000
Liability Derivatives, Estimated Fair Value	0		(222)
Stand-alone derivative instruments | TBA mortgage securities | Mortgage Banking
Derivative [Line Items]
Asset Derivatives, Notional Amount	50,000		15,000
Asset Derivatives, Estimated Fair Value	406		16
Liability Derivatives, Notional Amount	0		100,000
Liability Derivatives, Estimated Fair Value	0		(63)
Stand-alone derivative instruments | Forward loan sale commitments | Mortgage Banking
Derivative [Line Items]
Asset Derivatives, Notional Amount	126,000		259,000
Asset Derivatives, Estimated Fair Value	576		333
Liability Derivatives, Notional Amount	606,500		483,500
Liability Derivatives, Estimated Fair Value	(2,130)		(787)
Stand-alone derivative instruments | Interest rate lock commitments | Mortgage Banking
Derivative [Line Items]
Asset Derivatives, Notional Amount	499,337		404,557
Asset Derivatives, Estimated Fair Value	2,281		1,571
Liability Derivatives, Notional Amount	0		0
Liability Derivatives, Estimated Fair Value	0		$ 0
Stand-alone derivative instruments | Mortgage related derivatives
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	$ (581)	$ (10,141)

Derivative Financial Instrume81

Derivative Financial Instruments - Financial Instruments Eligible for Offset In Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial Assets
Financial Assets, Gross Amount Recognized	$ 38,174	$ 17,540
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	38,174	17,540
Repurchase Agreements, Financial Assets, Gross Amount Recognized	0	0
Repurchase Agreements, Financial Assets, Gross Amount Offset	0	0
Repurchase Agreements, Financial Assets, Net Amount Recognized	0	0
Total Financial Assets, Gross Amount Recognized	38,174	17,540
Total Financial Assets, Gross Amount Offset	0	0
Total Financial Assets, Net Amount Recognized	38,174	17,540
Financial Assets, Financial Instruments	(16,493)	(14,719)
Financial Assets, Collateral	(4,691)	0
Financial Assets, Net Amount	16,990	2,821
Repurchase Agreements, Financial Assets, Financial Instruments	0	0
Repurchase Agreements, Financial Assets, Collateral	0	0
Repurchase Agreements, Financial Assets, Net Amount	0	0
Total Financial Assets, Financial Instruments	(16,493)	(14,719)
Total Financial Assets, Collateral	(4,691)	0
Total Financial Assets, Net Amount	16,990	2,821
Financial Liabilities
Financial Liabilities, Gross Amount Recognized	19,290	27,947
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	19,290	27,947
Repurchase Agreements, Financial Liabilities, Gross Amount Recognized	225,962	232,789
Repurchase Agreements, Financial Liabilities, Gross Amount Offset	0	0
Repurchase Agreements, Financial Liabilities, Net Amount Recognized	225,962	232,789
Total Financial Liabilities, Gross Amount Recognized	245,252	260,736
Total Financial Liabilities, Gross Amount Offset	0	0
Total Financial Liabilities, Net Amount Recognized	245,252	260,736
Financial Liabilities, Financial Instruments	(16,493)	(14,719)
Financial Liabilities, Collateral	(1,308)	(13,223)
Financial Liabilities, Net Amount	1,489	5
Repurchase Agreements, Financial Liabilities, Financial Instruments	0	0
Repurchase Agreements, Financial Liabilities, Collateral	(225,962)	(232,789)
Repurchase Agreements, Financial Liabilities, Net Amount	0	0
Total Financial Liabilities, Financial Instruments	(16,493)	(14,719)
Total Financial Liabilities, Collateral	(227,270)	(246,012)
Total Financial Liabilities, Net Amount	1,489	5
Counterparty A
Financial Assets
Financial Assets, Net Amount Recognized	13,664	6,068
Financial Assets, Financial Instruments	(7,524)	(6,068)
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	6,140	0
Financial Liabilities
Financial Liabilities, Net Amount Recognized	7,524	13,807
Financial Liabilities, Financial Instruments	(7,524)	(6,068)
Financial Liabilities, Collateral	0	(7,739)
Financial Liabilities, Net Amount	0	0
Counterparty B
Financial Assets
Financial Assets, Net Amount Recognized	10,301	3,261
Financial Assets, Financial Instruments	(585)	(3,261)
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	9,716	0
Financial Liabilities
Financial Liabilities, Net Amount Recognized	585	5,595
Financial Liabilities, Financial Instruments	(585)	(3,261)
Financial Liabilities, Collateral	0	(2,334)
Financial Liabilities, Net Amount	0	0
Counterparty C
Financial Assets
Financial Assets, Net Amount Recognized	7,999	5,285
Financial Assets, Financial Instruments	(5,616)	(3,640)
Financial Assets, Collateral	(2,383)	0
Financial Assets, Net Amount	0	1,645
Financial Liabilities
Financial Liabilities, Net Amount Recognized	5,616	3,640
Financial Liabilities, Financial Instruments	(5,616)	(3,640)
Financial Liabilities, Collateral	0	0
Financial Liabilities, Net Amount	0	0
Other counterparties
Financial Assets
Financial Assets, Net Amount Recognized	6,210	2,926
Financial Assets, Financial Instruments	(2,768)	(1,750)
Financial Assets, Collateral	(2,308)	0
Financial Assets, Net Amount	1,134	1,176
Financial Liabilities
Financial Liabilities, Net Amount Recognized	5,565	4,905
Financial Liabilities, Financial Instruments	(2,768)	(1,750)
Financial Liabilities, Collateral	(1,308)	(3,150)
Financial Liabilities, Net Amount	1,489	5
Interest rate swap contracts, caps and floors
Financial Assets
Financial Assets, Gross Amount Recognized	26,570	11,659
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	26,570	11,659
Financial Liabilities
Financial Liabilities, Gross Amount Recognized	4,976	11,562
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	4,976	11,562
Foreign exchange contracts
Financial Assets
Financial Assets, Gross Amount Recognized	414	1,013
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	414	1,013
Financial Liabilities
Financial Liabilities, Gross Amount Recognized	3,475	953
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	3,475	953
Mortgage related derivatives
Financial Assets
Financial Assets, Gross Amount Recognized	11,190	4,868
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	11,190	4,868
Financial Liabilities
Financial Liabilities, Gross Amount Recognized	10,839	15,432
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	$ 10,839	$ 15,432

Operating Segments (Details)

Operating Segments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)segment	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments | segment	3
Net interest income	$ 153,381	$ 143,043
Provision for credit losses	7,508	3,734
Non-interest income	92,802	92,450
Non-interest expense	167,886	156,342
Income tax expense	14,032	20,880
Net income	56,757	54,537
Total assets	20,167,523	19,146,062	$ 20,086,940
Taylor Capital Group, Inc.
Segment Reporting Information [Line Items]
Pretax merger related costs	644	258
Banking
Segment Reporting Information [Line Items]
Net interest income	140,471	131,449
Provision for credit losses	7,579	3,527
Non-interest income	43,092	43,208
Non-interest expense	115,826	108,516
Income tax expense	13,608	15,660
Net income	46,550	46,954
Total assets	16,582,585	16,009,339
Leasing
Segment Reporting Information [Line Items]
Net interest income	2,482	2,269
Provision for credit losses	(24)	(135)
Non-interest income	24,856	21,463
Non-interest expense	15,496	13,844
Income tax expense	756	4,119
Net income	11,110	5,904
Total assets	1,360,117	1,173,558
Mortgage Banking
Segment Reporting Information [Line Items]
Net interest income	10,428	9,325
Provision for credit losses	(47)	342
Non-interest income	24,854	27,779
Non-interest expense	36,564	33,982
Income tax expense	(332)	1,101
Net income	(903)	1,679
Total assets	$ 2,224,821	$ 1,963,165

Preferred Stock (Details)

Preferred Stock (Details) $ / shares in Units, $ in Thousands	Feb. 15, 2018USD ($)$ / sharesshares	Nov. 22, 2017$ / sharesshares	Aug. 18, 2014$ / sharesshares	Mar. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017$ / sharesshares
Business Acquisition [Line Items]
Redemption of preferred stock | $				$ (100,000)
Series A Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares) | shares				4,000,000	4,000,000
Preferred stock, liquidation preference per share (in dollars per share)				$ 25	$ 25
Preferred stock, dividend rate (percent)			8.00%	8.00%	8.00%
Stock redeemed or called during periog (in shares) | shares	4,000,000
Preferred stock, redemption price per share (in dollars per share)	$ 25
Redemption of preferred stock | $	$ 100,000
Preferred stock redemption premium | $	$ 15,300
Series A Preferred Stock | Taylor Capital Merger
Business Acquisition [Line Items]
Stock conversion			1
Preferred stock, shares outstanding (in shares) | shares			4,000,000
Preferred stock, liquidation preference per share (in dollars per share)			$ 25
Preferred stock, dividend rate (percent)			8.00%
Series C Preferred Stock, Depository Shares
Business Acquisition [Line Items]
Preferred stock, liquidation preference per share (in dollars per share)		$ 25
Preferred stock, dividend rate (percent)		6.00%
Preferred stock, redemption price per share (in dollars per share)		$ 25
New issues of stock during period (in shares) | shares		8,000,000
Interest in preferred stock				0.025%
Series C Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares) | shares				0	0
Preferred stock, liquidation preference per share (in dollars per share)		$ 1,000		$ 1,000	$ 1,000
Preferred stock, dividend rate (percent)				8.00%	8.00%

Subsequent Event (Details)

Subsequent Event (Details) - USD ($)	3 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Mar. 31, 2017	Apr. 12, 2018
Subsequent Event [Line Items]
Impairment loss		$ 0	$ 0
Subsequent Event
Subsequent Event [Line Items]
Impairment loss	$ 3,600,000
Subsequent Event | National Mortgage Origination | Discontinued Operations
Subsequent Event [Line Items]
Impairment loss	$ 3,600,000
Subsequent Event | National Mortgage Origination | Discontinued Operations | Minimum
Subsequent Event [Line Items]
Expected one-time pre-tax costs				$ 37,000,000
Subsequent Event | National Mortgage Origination | Discontinued Operations | Maximum
Subsequent Event [Line Items]
Expected one-time pre-tax costs				$ 41,000,000