MB Financial 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	6-May-15
Document and Entity Information
Entity Registrant Name	MB FINANCIAL INC /MD
Entity Central Index Key	1139812
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		75,123,683
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
ASSETS
Cash and due from banks	$248,840	$256,804
Interest earning deposits with banks	52,212	55,277
Total cash and cash equivalents	301,052	312,081
Investment securities:
Securities available for sale, at fair value	1,589,424	1,654,752
Securities held to maturity, at amortized cost ($1,045,205 fair value at March 31, 2015 and $1,035,061 at December 31, 2014)	1,000,859	993,380
Non-marketable securities - FHLB and FRB stock	87,677	75,569
Total investment securities	2,677,960	2,723,701
Loans held for sale	686,838	737,209
Loans:
Total loans, excluding purchased credit impaired and covered loans	8,693,814	8,831,572
Purchased credit impaired and covered loans	227,514	251,645
Total loans	8,921,328	9,083,217
Less: Allowance for loan losses	113,412	110,026
Net loans	8,807,916	8,973,191
Lease investments, net	159,191	162,833
Premises and equipment, net	234,077	238,377
Cash surrender value of life insurance	134,401	133,562
Goodwill	711,521	711,521
Other intangibles	36,488	38,006
Mortgage servicing rights, at fair value	219,254	235,402
Other real estate owned, net	21,839	19,198
Other real estate owned related to FDIC-assisted transactions	17,890	19,328
Other assets	319,883	297,690
Total assets	14,328,310	14,602,099
Deposits:
Non-interest bearing	4,290,499	4,118,256
Interest bearing	6,729,002	6,872,686
Total deposits	11,019,501	10,990,942
Short-term borrowings	615,231	931,415
Long-term borrowings	85,477	82,916
Junior subordinated notes issued to capital trusts	185,874	185,778
Accrued expenses and other liabilities	363,934	382,762
Total liabilities	12,270,017	12,573,813
STOCKHOLDERS’ EQUITY
Preferred stock, ($0.01 par value, authorized 10,000,000 shares at March 31, 2015 and December 31, 2014; Series A, 8% perpetual non-cumulative, 4,000,000 shares issued and outstanding at March 31, 2015 and December 31, 2014, $25 liquidation value)	115,280	115,280
Common stock, ($0.01 par value; authorized 100,000,000 shares at March 31, 2015 and December 31, 2014; issued 75,355,257 shares at March 31, 2015 and 75,067,482 shares at December 31, 2014)	754	751
Additional paid-in capital	1,268,851	1,267,761
Retained earnings	651,178	629,677
Accumulated other comprehensive income	26,101	20,356
Less: 233,181 and 296,715 shares of treasury common stock, at cost, at March 31, 2015 and December 31, 2014, respectively	-5,277	-6,974
Controlling interest stockholders’ equity	2,056,887	2,026,851
Noncontrolling interest	1,406	1,435
Total stockholders’ equity	2,058,293	2,028,286
Total liabilities and stockholders’ equity	$14,328,310	$14,602,099

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	3 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Securities held to maturity, at amortized cost, fair value	$1,045,205	$1,035,061
Preferred stock, par or stated value per share (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, dividend rate, percentage	8.00%	8.00%
Preferred stock, shares issued	4,000,000	4,000,000
Preferred stock, shares outstanding	4,000,000	4,000,000
Preferred stock, liquidation preference per share (in dollars per share)	$25	$25
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, authorized shares	100,000,000	100,000,000
Common stock, issued shares	75,355,257	75,067,482
Treasury stock, shares	233,181	296,715

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Loans:
Taxable	$98,846		$53,946
Nontaxable	2,174		2,298
Investment securities:
Taxable	9,934		8,146
Nontaxable	9,113		8,067
Federal funds sold	0		5
Other interest earning accounts	62		113
Total interest income	120,129		72,575
Interest expense:
Deposits	4,645		3,769
Short-term borrowings	277		100
Long-term borrowings and junior subordinated notes	1,812		1,378
Total interest expense	6,734		5,247
Net interest income	113,395		67,328
Provision for credit losses	4,974		1,150
Net interest income after provision for credit losses	108,421		66,178
Non-interest income:
Lease financing, net	25,080		13,196
Mortgage banking revenue	24,544		59
Commercial deposit and treasury management fees	11,038		7,144
Trust and asset management fees	5,714		5,207
Card fees	3,927		2,701
Capital markets and international banking fees	1,928		978
Consumer and other deposit service fees	3,083		2,935
Brokerage fees	1,678		1,325
Loan service fees	1,485		965
Increase in cash surrender value of life insurance	839		827
Net (loss) gain on investment securities	-460		317
Net gain on sale of assets	4		7
Other operating income	2,408		951
Total non-interest income	81,268		36,612
Non-interest expenses:
Salaries and employee benefits	84,786		44,377
Occupancy and equipment	12,940		9,592
Computer services and telecommunication	8,904		5,084
Advertising and marketing	2,446		2,081
Professional and legal	2,670		1,779
Other intangibles amortization	1,518		1,240
Branch exit and facilities impairment charges	7,391		0
Net loss recognized on other real estate owned and other related	896		583
Prepayment fees on interest bearing liabilities	85		0
Other operating expenses	18,284		11,311
Total non-interest expenses	139,920	[1]	76,047
Income before income taxes	49,769		26,743
Income tax expense	15,658		6,774
Net income	34,111		19,969
Dividends on preferred shares	2,000		0
Net income available to common stockholders	$32,111		$19,969
Common share data:
Basic earnings per common share	$0.43		$0.37
Diluted earnings per common share	$0.43		$0.36
Weighted average common shares outstanding for basic earnings per common share	74,567,104		54,639,951
Diluted weighted average common shares outstanding for diluted earnings per common share	75,164,716		55,265,188
[1]	Includes merger related expenses of $8.1 million and $680 thousand in the banking segment for the three months ended March 31, 2015 and 2014, respectively.

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$34,111	$19,969
Unrealized holding gains on investment securities, net of reclassification adjustments	9,404	4,946
Reclassification adjustment for amortization of unrealized gains on investment securities transferred to held to maturity from available for sale	-402	-1,376
Reclassification adjustments for losses (gains) included in net income	460	-317
Other comprehensive income, before tax	9,462	3,253
Income tax expense related to items of other comprehensive income	-3,717	-1,274
Other comprehensive income, net of tax	5,745	1,979
Comprehensive income	$39,856	$21,948

CONSOLIDATED_STATEMENTS_OF_CHA

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $)	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income, Net of Tax	Treasury Stock	Noncontrolling Interest
In Thousands, unless otherwise specified
Beginning balance at Dec. 31, 2013	$1,326,682	$0	$551	$738,053	$581,998	$8,383	($3,747)	$1,444
Increase (Decrease) in Stockholders' Equity
Net income	20,039				19,969			70
Other comprehensive income, net of tax	1,979					1,979
Cash dividends declared on common stock	-6,666				-6,666
Restricted common stock activity, net of tax	104		2	102
Stock option activity, net of tax	27			27
Repurchase of common shares in connection with employee benefit plans and held in trust for deferred compensation plan	-334			51			-385
Stock-based compensation expense	2,012			2,012
Distributions to noncontrolling interest	-63							-63
Ending balance at Mar. 31, 2014	1,343,780	0	553	740,245	595,301	10,362	-4,132	1,451
Beginning balance at Dec. 31, 2014	2,028,286	115,280	751	1,267,761	629,677	20,356	-6,974	1,435
Increase (Decrease) in Stockholders' Equity
Net income	34,182				34,111			71
Other comprehensive income, net of tax	5,745					5,745
Cash dividends declared on preferred shares	-2,000				-2,000
Cash dividends declared on common stock	-10,610				-10,610
Restricted common stock activity, net of tax	135		3	-2,744			2,876
Stock option activity, net of tax	35			35
Repurchase of common shares in connection with employee benefit plans and held in trust for deferred compensation plan	-985			194			-1,179
Stock-based compensation expense	3,605			3,605
Distributions to noncontrolling interest	-100							-100
Ending balance at Mar. 31, 2015	$2,058,293	$115,280	$754	$1,268,851	$651,178	$26,101	($5,277)	$1,406

CONSOLIDATED_STATEMENTS_OF_CHA1

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Stockholders' Equity [Abstract]
Cash dividends declared (in dollars per share)	$0.14	$0.12

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash Flows From Operating Activities
Net income	$34,111	$19,969
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of premises and equipment and leased equipment	14,737	13,653
Branch exit and facilities impairment charges	7,391	0
Compensation expense for share-based payment plans	3,605	2,012
Net gain on sales of premises and equipment and leased equipment	-167	-630
Amortization of other intangibles	1,518	1,240
Provision for credit losses	4,974	1,150
Deferred income tax expense	8,384	-1,406
Amortization of premiums and discounts on investment securities, net	11,231	11,110
Accretion of premiums and discounts on loans, net	-9,879	-550
Accretion of FDIC indemnification asset	-24	-31
Net loss (gain) on investment securities	460	-317
Proceeds from sale of loans held for sale	1,741,704	3,247
Origination of loans held for sale	-1,701,005	-3,342
Net gain on sale of loans held for sale	-12,574	-59
Change in fair value of mortgage servicing rights	32,793	0
Net loss on sales of other real estate owned	888	122
Net loss on other real estate owned related to FDIC-assisted transactions	273	65
Increase in cash surrender value of life insurance	-839	-827
(Increase) decrease in other assets, net	-38,984	23,713
Decrease in other liabilities, net	-41,616	-36,590
Net cash provided by operating activities	56,981	32,529
Cash Flows From Investing Activities
Decrease in federal funds sold	0	35,450
Proceeds from sales of investment securities available for sale	28,067	11,375
Proceeds from maturities and calls of investment securities available for sale	51,922	61,989
Purchases of investment securities available for sale	-11,570	-37,670
Proceeds from maturities and calls of investment securities held to maturity	19,177	11,736
Purchases of investment securities held to maturity	-24,448	-12,836
Purchases of non-marketable securities - FHLB and FRB stock	-12,108	-15
Net decrease in loans	190,353	134,795
Purchases in mortgage servicing rights	-85	0
Purchases of premises and equipment and leased equipment	-11,557	-5,572
Proceeds from sales of premises and equipment and leased equipment	1,326	4,219
Proceeds from sale of other real estate owned	1,086	2,778
Proceeds from sale of other real estate owned related to FDIC-assisted transactions	2,087	631
Net proceeds from FDIC related covered assets	-3,773	3,032
Net cash provided by investing activities	230,477	209,912
Cash Flows From Financing Activities
Net increase in deposits	28,559	104,488
Net decrease in short-term borrowings	-316,184	-303,517
Proceeds from long-term borrowings	7,650	6,117
Principal paid on long-term borrowings	-5,089	-2,612
Treasury stock transactions, net	-985	-334
Stock options exercised	45	61
Excess tax expense from share-based payment arrangements	12	95
Dividends paid on preferred stock	-2,000	0
Dividends paid on common stock	-10,495	-6,576
Net cash used in financing activities	-298,487	-202,278
Net (decrease) increase in cash and cash equivalents	-11,029	40,163
Cash and cash equivalents:
Beginning of period	312,081	473,459
End of period	301,052	513,622
Cash payments for:
Interest paid to depositors and other borrowed funds	7,438	5,275
Income tax payments, net	987	1,967
Supplemental Schedule of Noncash Investing Activities:
Investment securities held to maturity purchased not settled	6,416	9,941
Loans held for sale transferred to loans held for investment	20,829	0
Loans transferred to other real estate owned	4,615	539
Loans transferred to other real estate owned related to FDIC-assisted transactions	1,345	3,419
Loans transferred to repossessed vehicles	286	205
Operating leases rewritten as direct finance leases included as loans	$5,590	$316

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Accounting Policies [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 position, results of operations and cash flows for the interim periods have been made. The results of operations for the three months ended March 31, 2015 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, 2014.
	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_G

New Authoritative Accounting Guidance	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Authoritative Accounting Guidance	New Authoritative Accounting Guidance
	ASC Topic 310 “Receivables.” New authoritative accounting guidance under ASC Topic 310, “Receivables” amended prior guidance to clarify that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical
	possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additionally, the amendments require interim and annual disclosures. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	New authoritative accounting guidance under ASC Topic 310, “Receivables” amended prior guidance to require an entity to derecognize a mortgage loan and recognize a separate other receivable upon foreclosure if (i) the loan has a government guarantee that is not separable from the loan before foreclosure, (ii) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on that guarantee, and the creditor has the ability to recover under that claim, and (iii) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. The separate other receivable is to be measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have a material impact on the Company's statements of operations or financial condition.
	ASC Topic 323 “Investments - Equity Method and Joint Ventures.” New authoritative accounting guidance under ASC Topic 323, “Investments - Equity Method and Joint Ventures” amended prior guidance to permit entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the statement of operation as a component of income tax expense. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	ASC Topics 205 “Presentation of Financial Statements” and 360 “Property, Plant, and Equipment.” New authoritative accounting guidance under ASC Topic 205, “Presentation of Financial Statements” and ASC Topic 360 “Property, Plant, and Equipment” amended prior guidance to change the requirements for reporting discontinued operations. The disposal of a component of an entity or group of components of an entity is required to be reported in discontinued operations if the disposal represents a strategic shift that has (or will have) a major effect on an entity's operations and financial results. The new authoritative guidance also requires additional disclosures about discontinued operations. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	ASC Topic 860 “Transfers and Servicing.” New authoritative accounting guidance under ASC Topic 860, “Transfers and Servicing” amended prior guidance to change the accounting for repurchase-to-maturity transactions to secured borrowing accounting and to require separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. The new authoritative guidance also requires disclosures for a transfer of a financial asset accounted for as a sale and an agreement with the same transferee entered into in contemplation of the initial transfer that results in the transferor retaining substantially all of the exposure to the economic return on the transferred financial asset throughout the term of the transaction. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an 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” amended prior guidance to require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	ASC Topic 225 “Income Statement - Extraordinary and Unusual Items.” New authoritative accounting guidance under ASC Topic 225, “Income Statement - Extraordinary and Unusual Items” amended prior guidance to eliminate the concept of extraordinary items. The new authoritative guidance will be effective for reporting periods after January 1, 2016 and is not expected to have a significant impact on the Company's statements of operations or financial condition.
	ASC Topic 810 “Consolidation.” New authoritative accounting guidance under ASC Topic 810, “Consolidation” amended prior guidance over the consolidation of certain legal entities. The new authoritative guidance modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership, affects the consolidation analysis of reporting entities that are involved with variable interest entities and provides a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements similar to those for registered money market funds. The new authoritative guidance will be effective for reporting periods after January 1, 2016 and is not expected to have a significant impact on the Company's statements of operations or financial condition.

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2015
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,
		2015		2014
	Distributed earnings allocated to common stock	$	10,610	$	6,666
	Undistributed earnings	23,501		13,303
	Net income	34,111		19,969
	Less: preferred stock dividends	2,000		—
	Net income available to common stockholders	32,111		19,969
	Less: earnings allocated to participating securities	1		—
	Earnings allocated to common stockholders	$	32,110	$	19,969
	Weighted average shares outstanding for basic earnings per common share	74,567,104		54,639,951
	Dilutive effect of equity awards	597,612		625,237
	Weighted average shares outstanding for diluted earnings per common share	75,164,716		55,265,188
	Basic earnings per common share	$	0.43	$	0.37
	Diluted earnings per common share	0.43		0.36

Business_Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Business Combination	Business Combination
	On August 18, 2014, the Company acquired Taylor Capital Group, Inc. (“Taylor Capital”), a bank holding company and the parent company of Cole Taylor Bank, a commercial bank headquartered in Chicago, through the merger (the “Merger”) of Taylor Capital with and into the Company, followed immediately by the merger of Cole Taylor Bank with and into MB Financial Bank. This transaction solidifies the Company's market position in Chicago and diversifies its revenue streams. At the effective time of the Merger (the “Effective Time”), each share of the common stock of Taylor Capital and each share of nonvoting convertible preferred stock of Taylor Capital converted into the right to receive (1) 0.64318 of a share of the common stock of the Company, and (2) $4.08 in cash. All “in-the-money” Taylor Capital stock options and warrants outstanding immediately prior to the Effective Time were canceled in exchange for the right to receive a cash payment as provided in the merger agreement, as were the outstanding unvested restricted stock awards of Taylor Capital; however, the cash consideration payable for such restricted stock awards will remain subject to vesting or other lapse restrictions. Each share of Taylor Capital’s perpetual non-cumulative preferred stock, Series A, converted into the right to receive one share of the Company’s perpetual non-cumulative preferred stock, Series A.
	The Company issued approximately 19.6 million shares of common stock and paid approximately $129.5 million in cash in the Merger. For the “in-the-money” Taylor Capital stock options and warrants, the Company paid in the aggregate approximately $4.4 million in cash. For the outstanding unvested Taylor Capital restricted stock awards, the Company will pay or has paid in the aggregate up to approximately $3.7 million in cash, as and to the extent such awards vest. The $129.5 million cash consideration includes payments for the Taylor Capital stock options, warrants and restricted stock awards.
	This business combination was accounted for under the acquisition method of accounting.  Accordingly, the results of operations of the acquired company have been included in the Company’s results of operations since the date of acquisition.  Under this method of accounting, the assets acquired, liabilities assumed and consideration paid are recorded at their estimated fair values.  The excess cost over fair value of net assets acquired is recorded as goodwill.  As the consideration paid for Taylor Capital exceeded the net assets acquired, goodwill of $288.2 million was recorded on the acquisition and was allocated to the banking segment. Goodwill recorded in the transaction, which reflects the increased Chicago market share and related synergies expected from the combined operations, is not tax deductible. The amounts recognized for the business combination in the financial statements as of March 31, 2015 have been determined to be final.
	Estimated fair values of the assets acquired and liabilities assumed in the Taylor Capital transaction, as of the closing date of the transaction were as follows (in thousands):
			August 18,
			2014
	ASSETS
	Cash and cash equivalents		$	154,684
	Investment securities available for sale		826,691
	Investment securities held to maturity		22,599
	Non-marketable securities - FRB and FHLB Stock		50,620
	Loans held for sale		670,671
	Loans		3,532,211
	Leases investments		11,885
	Premises and equipment		19,701
	Goodwill		288,152
	Core deposit intangible		20,079
	Mortgage servicing rights		224,453
	Other real estate owned		4,720
	Other assets		130,478
	Total assets		$	5,956,944
	LIABILITIES
	Deposits		$	3,953,213
	Short-term borrowings		1,035,800
	Junior subordinated notes issued to capital trusts		80,843
	Accrued expenses and other liabilities		123,028
	Total liabilities		$	5,192,884
	Series A preferred stock at $28.82 per share at August 15, 2014		$	115,280
	Total identifiable net assets less Series A preferred stock		$	648,780
	Consideration excluding Series A preferred stock:
	Market value of common stock at $26.49 per share at August 15, 2014 (19,602,482 shares of common stock issued)		$	519,270
	Cash paid		129,510
	Total fair value of consideration, excluding Series A preferred stock		$	648,780
	The Company's Series A preferred stock was valued based upon the closing price of Taylor Capital's Series A preferred stock on August 15, 2014, the last trading day before the Merger date.
	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 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 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 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 (computed on a loan by loan basis) and the principal outstanding is accreted over the remaining life of the loans. We anticipate recording a provision for the acquired portfolio in future quarters related to renewing Taylor Capital loans which will largely offset the accretion from the pass rated loans.
	In accordance with ASC 310-30, for both purchased non-impaired loans and purchased credit-impaired loans ("PCI loans"), 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 when there is a reasonable expectation about the amount and timing of such cash flows.
	The following table presents the acquired loans as of the acquisition date (in thousands):
			PCI Loans			Non-PCI Loans
	Contractually required principal and interest payments		$	244,650		$	3,707,463
	Contractually required interest payments not expected to be collected due to estimated prepayments		—			(302,329		)
	Nonaccretable difference		(34,219		)	—
	Cash flows expected to be collected		210,431			3,405,134
	Accretable difference		(5,626		)	(77,728		)
	Fair value of acquired loans		$	204,805		$	3,327,406
	The Company recorded $8.1 million and $680 thousand in pre-tax merger related expenses for the three months ended March 31, 2015 and 2014, respectively. These merger related expenses primarily relate to retention and severance compensation costs, professional and legal fees and branch exit and facilities impairment charges. The data processing systems were converted in September 2014.
	The following table provides the unaudited pro forma information for the results of operations for the three months ended March 31, 2014, as if the acquisition had occurred January 1, 2014. The pro forma results combine the historical results of Taylor Capital into the Company's consolidated statement of operations including the impact of certain purchase accounting adjustments including loan discount accretion, investment securities discount accretion, intangible assets amortization, deposit premium accretion and borrowing discount amortization. The pro forma results have been prepared for comparative purposes only and are not necessarily indicative of the results that would have been obtained had the acquisition actually occurred on January 1, 2014. No assumptions have been applied to the pro forma results of operations regarding possible revenue enhancements, provision for credit losses, expense efficiencies or asset dispositions. Net income in the table below includes merger related expenses.
			Pro Forma
			Three Months Ended
			March 31,
			2014
	(in thousands)
	Total revenues (net interest income plus non-interest income)		$	185,028
	Net income		34,752
	Revenues and earnings of the acquired company since the acquisition date have not been disclosed as it is not practicable as Taylor Capital was merged into the Company and separate financial information is not readily available.

Investment_Securities

Investment Securities	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities
	Amortized cost and fair value of investment securities were as follows as of the dates indicated (in thousands):
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Gains			Losses
	31-Mar-15
	Available for Sale
	U.S. Government sponsored agencies and enterprises	$	64,411		$	1,659		$	—		$	66,070
	States and political subdivisions	381,704			21,953			(29		)	403,628
	Residential mortgage-backed securities	666,904			12,383			(812		)	678,475
	Commercial mortgage-backed securities	174,823			3,816			(181		)	178,458
	Corporate bonds	250,543			3,462			(1,963		)	252,042
	Equity securities	10,587			164			—			10,751
	Total Available for Sale	1,548,972			43,437			(2,985		)	1,589,424
	Held to Maturity
	States and political subdivisions	764,931			32,136			(284		)	796,783
	Residential mortgage-backed securities	235,928			12,494			—			248,422
	Total Held to Maturity	1,000,859			44,630			(284		)	1,045,205
	Total	$	2,549,831		$	88,067		$	(3,269	)	$	2,634,629
	31-Dec-14
	Available for Sale
	U.S. Government sponsored agencies and enterprises	$	64,612		$	1,281		$	(20	)	$	65,873
	States and political subdivisions	390,076			20,846			(68		)	410,854
	Residential mortgage-backed securities	713,413			8,977			(1,827		)	720,563
	Commercial mortgage-backed securities	186,110			1,772			(220		)	187,662
	Corporate bonds	259,526			2,428			(2,751		)	259,203
	Equity securities	10,531			66			—			10,597
	Total Available for Sale	1,624,268			35,370			(4,886		)	1,654,752
	Held to Maturity
	States and political subdivisions	752,558			30,089			(382		)	782,265
	Residential mortgage-backed securities	240,822			11,974			—			252,796
	Total Held to Maturity	993,380			42,063			(382		)	1,035,061
	Total	$	2,617,648		$	77,433		$	(5,268	)	$	2,689,813
	The Company has no direct exposure to the State of Illinois, but approximately 25% of the state and political subdivisions portfolio consisted of securities issued by municipalities located in Illinois as of March 31, 2015. Approximately 93% of such securities were general obligation issues as of March 31, 2015.
	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, 2015 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
	States and political subdivisions	$	4,761		$	(10	)	$	2,253		$	(19	)	$	7,014	$	(29	)
	Residential mortgage-backed securities	62,437			(278		)	43,263			(534		)	105,700		(812		)
	Commercial mortgage-backed securities	16,752			(181		)	—			—			16,752		(181		)
	Corporate bonds	26,242			(459		)	9,675			(1,504		)	35,917		(1,963		)
	Total Available for Sale	110,192			(928		)	55,191			(2,057		)	165,383		(2,985		)
	Held to Maturity
	States and political subdivisions	36,619			(137		)	6,240			(147		)	42,859		(284		)
	Total	$	146,811		$	(1,065	)	$	61,431		$	(2,204	)	$	208,242	$	(3,269	)
	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, 2014 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	$	9,644		$	(20	)	$	—		$	—		$	9,644	$	(20	)
	States and political subdivisions	7,784			(21		)	3,558			(47		)	11,342		(68		)
	Residential mortgage-backed securities	235,818			(1,336		)	29,373			(491		)	265,191		(1,827		)
	Commercial mortgage-backed securities	89,509			(220		)	—			—			89,509		(220		)
	Corporate bonds	62,693			(1,159		)	9,675			(1,592		)	72,368		(2,751		)
	Total Available for Sale	405,448			(2,756		)	42,606			(2,130		)	448,054		(4,886		)
	Held to Maturity
	States and political subdivisions	28,786			(130		)	14,238			(252		)	43,024		(382		)
	Total	$	434,234		$	(2,886	)	$	56,844		$	(2,382	)	$	491,078	$	(5,268	)
	The total number of security positions in the investment portfolio in an unrealized loss position at March 31, 2015 was 97 compared to 168 at December 31, 2014. 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, 2015, 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, 2015, 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 (losses) gains recognized on investment securities available for sale were as follows (in thousands):
	Three Months Ended
	March 31,
	2015			2014
Realized gains	$	759		$	318
Realized losses	(1,219		)	(1		)
Net (losses) gains	$	(460	)	$	317
The amortized cost and fair value of investment securities as of March 31, 2015 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	$	17,722		$	17,770
Due after one year through five years	291,975			294,881
Due after five years through ten years	42,645			44,133
Due after ten years	344,316			364,956
Equity securities	10,587			10,751
Residential and commercial mortgage-backed securities	841,727			856,933
	1,548,972			1,589,424
Held to maturity:
Due in one year or less	52,102			52,249
Due after one year through five years	222,670			224,797
Due after five years through ten years	99,975			104,546
Due after ten years	390,184			415,191
Residential mortgage-backed securities	235,928			248,422
	1,000,859			1,045,205
Total	$	2,549,831		$	2,634,629
Investment securities with a carrying amount of $1.5 billion at March 31, 2015 and December 31, 2014, respectively, were pledged as collateral on public deposits and for other purposes as required or permitted by law, while only $908.6 million and $980.4 million were required to be pledged at March 31, 2015 and December 31, 2014, respectively. Of those pledged, the Company had investment securities pledged as collateral for advances from the Federal Home Loan Bank of $200.9 million and $226.9 million at March 31, 2015 and December 31, 2014, respectively.

Loans

Loans	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Loans	Loans
	Loans consist of the following at (in thousands):
			March 31,				December 31,
			2015				2014
	Commercial loans		$	3,258,652			$	3,245,206
	Commercial loans collateralized by assignment of lease payments		1,628,031				1,692,258
	Commercial real estate		2,525,640				2,544,867
	Residential real estate		505,558				503,287
	Construction real estate		184,105				247,068
	Indirect vehicle		273,105				268,840
	Home equity		241,078				251,909
	Other consumer loans		77,645				78,137
	Total loans, excluding purchased credit-impaired and covered loans		8,693,814				8,831,572
	Purchased credit-impaired and covered loans		227,514				251,645
	Total loans		$	8,921,328			$	9,083,217
	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 and asset-based loans, credit risk tends to be geographically concentrated in that a majority of the loan customers are located in the markets serviced by MB Financial Bank.
	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 Company's Board of Directors on a regular basis.
	Commercial Loans. Commercial credit is extended primarily 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 and projected cash flow of the borrower and secondarily on the underlying collateral provided by the borrower. The cash flows of borrowers, however, may not behave 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 or Standard & Poor's Rating Services or, in the event the related lessee has not received any such rating, where the related lessee would be viewed under the underwriting policies of the Company as an investment grade company. 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.
	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 cash flow loans and the repayment of these loans is largely dependent on the successful operation 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 controlled 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, they 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 primarily residential real estate, home equity lines and loans, credit cards, and indirect vehicle loans (motorcycle, powersports, recreational and marine 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 Company relationship with the borrower. Indirect loan and credit card underwriting involves the use of risk-based pricing in the underwriting process.
	A collateral pledge agreement exists whereby at all times, the Company must keep on hand, free of all other pledges, liens, and encumbrances, first mortgage loans and home equity loans with unpaid principal balances aggregating no less than 133% for first mortgage loans and 250% for home equity loans of the outstanding advances from the Federal Home Loan Bank.  As of March 31, 2015 and December 31, 2014, the Company had $3.5 billion and $2.0 billion, respectively, of loans pledged as collateral for long-term Federal Home Loan Bank advances and third party letters of credit, while only $1.3 billion were required to be pledged at March 31, 2015 and December 31, 2014, respectively.
	The following table presents the contractual aging of the recorded investment in past due loans by class of loans as of March 31, 2015 and December 31, 2014 (in thousands):
			Current				30-59 Days				60-89 Days				Loans Past Due			Total			Total
							Past Due				Past Due				90 Days or More			Past Due
	31-Mar-15
	Commercial		$	3,220,398			$	27,393			$	1,899			$	8,962		$	38,254		$	3,258,652
	Commercial collateralized by assignment of lease payments		1,611,508				12,350				2,062				2,111			16,523			1,628,031
	Commercial real estate
	Healthcare		344,393				—				—				—			—			344,393
	Industrial		334,667				—				—				2,309			2,309			336,976
	Multifamily		372,358				2,823				—				1,336			4,159			376,517
	Retail		436,710				240				1,817				2,054			4,111			440,821
	Office		243,266				1,235				23				2,048			3,306			246,572
	Other		776,851				1,156				281				2,073			3,510			780,361
	Residential real estate		492,557				5,060				951				6,990			13,001			505,558
	Construction real estate		183,768				—				—				337			337			184,105
	Indirect vehicle		270,474				1,933				473				225			2,631			273,105
	Home equity		232,851				2,551				268				5,408			8,227			241,078
	Other consumer		77,546				76				23				—			99			77,645
	Total loans, excluding purchased credit-impaired and covered loans		8,597,347				54,817				7,797				33,853			96,467			8,693,814
	Purchased credit-impaired and covered loans		134,140				8,291				1,685				83,398			93,374			227,514
	Total loans		$	8,731,487			$	63,108			$	9,482			$	117,251		$	189,841		$	8,921,328
	Non-performing loan aging		$	45,674			$	3,018			$	911			$	33,675		$	37,604		$	83,278
	31-Dec-14
	Commercial		$	3,231,571			$	8,222			$	—			$	5,413		$	13,635		$	3,245,206
	Commercial collateralized by assignment of lease payments		1,679,991				2,025				6,095				4,147			12,267			1,692,258
	Commercial real estate
	Healthcare		342,984				—				—				—			—			342,984
	Industrial		333,907				944				—				3,182			4,126			338,033
	Multifamily		417,504				1,377				—				1,517			2,894			420,398
	Retail		432,718				2,481				652				2,325			5,458			438,176
	Office		244,166				—				—				2,127			2,127			246,293
	Other		754,031				307				2,421				2,224			4,952			758,983
	Residential real estate		485,492				8,038				2,319				7,438			17,795			503,287
	Construction real estate		246,731				—				—				337			337			247,068
	Indirect vehicle		265,296				2,516				702				326			3,544			268,840
	Home equity		242,756				2,717				1,039				5,397			9,153			251,909
	Other consumer		78,106				16				12				3			31			78,137
	Total loans, excluding purchased credit-impaired and covered loans		8,755,253				28,643				13,240				34,436			76,319			8,831,572
	Purchased credit-impaired and covered loans		158,215				4,432				585				88,413			93,430			251,645
	Total loans		$	8,913,468			$	33,075			$	13,825			$	122,849		$	169,749		$	9,083,217
	Non-performing loan aging		$	46,149			$	5,764			$	1,099			$	34,075		$	40,938		$	87,087
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 and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
		March 31, 2015								December 31, 2014
						Loans past due								Loans past due
		Non-accrual				90 days or more				Non-accrual				90 days or more
						and still accruing								and still accruing
Commercial		$	13,897			$	75			$	14,088			$	—
Commercial collateralized by assignment of lease payments		3,602				741				2,404				3,566
Commercial real estate:
Healthcare		—				—				—				—
Industrial		4,816				—				6,371				—
Multifamily		5,008				—				5,333				—
Office		3,268				—				3,644				464
Retail		2,898				—				2,986				—
Other		13,655				—				13,541				324
Residential real estate		16,925				891				17,311				—
Construction real estate		337				—				337				—
Indirect vehicle		1,473				—				1,542				—
Home equity		15,672				—				15,171				—
Other consumer		20				—				5				—
Total		$	81,571			$	1,707			$	82,733			$	4,354
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. Risk ratings are updated any time the situation warrants and at least annually. Loans listed as not rated are included in groups of homogeneous loans with similar risk and loss characteristics.
The following tables present the risk category of loans by class of loans based on the most recent analysis performed, excluding purchased credit-impaired and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
		Pass				Special				Substandard				Doubtful			Total
						Mention
31-Mar-15
Commercial		$	3,029,893			$	155,032			$	73,727			$	—		$	3,258,652
Commercial collateralized by assignment of lease payments		1,614,968				935				12,128				—			1,628,031
Commercial real estate
Healthcare		340,036				4,357				—				—			344,393
Industrial		314,666				13,200				9,110				—			336,976
Multifamily		368,675				1,287				6,555				—			376,517
Retail		426,760				4,165				9,896				—			440,821
Office		225,451				13,544				7,577				—			246,572
Other		727,643				17,426				35,292				—			780,361
Construction real estate		183,244				524				337				—			184,105
Total		$	7,231,336			$	210,470			$	154,622			$	—		$	7,596,428
31-Dec-14
Commercial		$	3,036,069			$	178,984			$	30,153			$	—		$	3,245,206
Commercial collateralized by assignment of lease payments		1,680,736				6,853				4,669				—			1,692,258
Commercial real estate
Healthcare		338,622				4,362				—				—			342,984
Industrial		314,225				8,817				14,991				—			338,033
Multifamily		412,824				920				6,654				—			420,398
Retail		423,842				2,740				11,594				—			438,176
Office		229,947				8,524				7,822				—			246,293
Other		708,447				22,013				28,523				—			758,983
Construction real estate		246,204				527				337				—			247,068
Total		$	7,390,916			$	233,740			$	104,743			$	—		$	7,729,399
Approximately $46.9 million and $49.1 million of the substandard and doubtful loans were non-performing as of March 31, 2015 and December 31, 2014, respectively.
For residential real estate, home equity, indirect vehicle and other consumer loan classes, which are not rated, the Company 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 and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
		Performing				Non-performing				Total
31-Mar-15
Residential real estate		$	487,742			$	17,816			$	505,558
Indirect vehicle		271,631				1,474				273,105
Home equity		225,407				15,671				241,078
Other consumer		77,625				20				77,645
Total		$	1,062,405			$	34,981			$	1,097,386
31-Dec-14
Residential real estate		$	485,976			$	17,311			$	503,287
Indirect vehicle		267,297				1,543				268,840
Home equity		236,739				15,170				251,909
Other consumer		78,132				5				78,137
Total		$	1,068,144			$	34,029			$	1,102,173
The following tables present loans individually evaluated for impairment by class of loans, excluding purchased credit-impaired and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
		31-Mar-15
																	Three Months Ended
		Unpaid				Recorded				Partial				Allowance for			Average			Interest
		Principal				Investment				Charge-offs				Loan Losses			Recorded			Income
		Balance												Allocated			Investment			Recognized
With no related allowance recorded:
Commercial		$	9,686			$	8,925			$	761			$	—		$	10,640		$	—
Commercial collateralized by assignment of lease payments		1,508				1,508				—				—			1,626			29
Commercial real estate:
Healthcare		—				—				—				—			—			—
Industrial		5,846				4,670				1,176				—			4,962			—
Multifamily		1,698				1,698				—				—			1,792			7
Retail		2,019				807				1,212				—			825			—
Office		1,608				1,031				577				—			1,609			—
Other		1,490				1,465				25				—			1,527			—
Residential real estate		970				970				—				—			—			—
Construction real estate		—				—				—				—			—			—
Indirect vehicle		—				—				—				—
Home equity		1,025				1,025				—				—			—			—
Other consumer		—				—				—				—			—			—
With an allowance recorded:
Commercial		6,464				6,464				—				2,051			6,760			—
Commercial collateralized by assignment of lease payments		2,145				2,145				—				1,534			1,331			14
Commercial real estate:
Healthcare		—				—				—				—			—			—
Industrial		146				146				—				37			49			—
Multifamily		5,723				4,749				974				664			5,926			8
Retail		8,889				7,493				1,396				626			7,710			—
Office		2,369				1,866				503				484			2,274			—
Other		12,247				12,227				20				100			13,207			—
Residential real estate		14,153				14,153				—				3,045			14,407			—
Construction real estate		2,708				337				2,371				162			431			—
Indirect vehicle		164				164				—				14			372			—
Home equity		26,954				26,954				—				2,348			27,213			—
Other consumer		—				—				—				—			—			—
Total		$	107,812			$	98,797			$	9,015			$	11,065		$	102,661		$	58
		31-Dec-14
		Unpaid				Recorded				Partial				Allowance for			Average			Interest
		Principal				Investment				Charge-offs				Loan Losses			Recorded			Income
		Balance												Allocated			Investment			Recognized
With no related allowance recorded:
Commercial		$	9,752			$	8,992			$	760			$	—		$	10,324		$	—
Commercial collateralized by assignment of lease payments		2,316				2,316				—				—			2,569			121
Commercial real estate:
Healthcare		—				—				—				—			—			—
Industrial		9,115				5,858				3,257				—			7,870			—
Multifamily		1,733				1,733				—				—			1,928			52
Retail		2,025				813				1,212				—			3,465			—
Office		—				—				—				—			1,127			—
Other		1,479				1,465				14				—			5,249			—
Residential real estate		1,941				1,941				—				—			2,740			—
Construction real estate		—				—				—				—			34			—
Indirect vehicle		—				—				—				—			—			—
Home equity		577				577				—				—			762			—
Other consumer		—				—				—				—			—			—
With an allowance recorded:
Commercial		7,987				7,987				—				2,395			14,227			—
Commercial collateralized by assignment of lease payments		715				715				—				105			1,515			91
Commercial real estate:
Healthcare		—				—				—				—			—			—
Industrial		517				513				4				130			4,982			—
Multifamily		5,680				4,709				971				996			6,354			131
Retail		9,264				7,897				1,367				720			8,547			—
Office		4,528				2,986				1,542				545			2,833			—
Other		12,612				12,527				85				136			11,022			12
Residential real estate		14,234				14,234				—				3,126			14,632			—
Construction real estate		2,707				337				2,370				162			455			—
Indirect vehicle		227				227				—				14			358			—
Home equity		25,927				25,705				222				2,153			25,672			—
Other consumer		—				—				—				—			—			—
Total		$	113,336			$	101,532			$	11,804			$	10,482		$	126,665		$	407
Impaired loans included accruing restructured loans of $16.9 million and $15.6 million that have been modified and are performing in accordance with those modified terms as of March 31, 2015 and December 31, 2014, respectively.  In addition, impaired loans included $25.5 million and $25.8 million of non-performing, restructured loans as of March 31, 2015 and December 31, 2014, 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. Programs that we offer to residential real estate borrowers include the Home Affordable Refinance Program (“HARP”), a restructuring program similar to the Home Affordable Modification Program (“HAMP”) for first mortgage borrowers, the Second Lien Modification Program (“2MP”) and similar programs for home equity borrowers in keeping with the restructuring techniques discussed above.
Periodically, the Company will restructure a note into two separate notes (A/B structure), charging off the entire B portion of the note. The A note is structured with appropriate loan-to-value and cash flow coverage ratios that provide for a high likelihood of repayment. The A note is classified as a non-performing note until the borrower has displayed a historical payment performance for a reasonable time prior to and subsequent to the restructuring. A period of sustained repayment for at least six months generally is required to return the note to accrual status provided that management has determined that the performance is reasonably expected to continue. The A note will be classified as a restructured note (either performing or non-performing) through the calendar year of the restructuring that the historical payment performance has been established. As of March 31, 2015 and December 31, 2014, there was one A/B structure with a recorded investment of $1.0 million, which is included above as an accruing restructured loan.
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 loss 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, 2015 (dollars in thousands):
		31-Mar-15
		Number of		Pre-Modification Recorded				Post-Modification Recorded				Charge-offs and
		Loans		Investment				Investment				Specific Reserves
Performing:
Home equity		6		$	2,346			$	2,346			$	—
Total		6		$	2,346			$	2,346			$	—
Non-Performing:
Indirect vehicle		3		$	9			$	9			$	—
Home equity		5		798				798				122
Total		8		$	807			$	807			$	122
The following table presents loans that were restructured during the three months ended March 31, 2014 (dollars in thousands):
		31-Mar-14
		Number of			Pre-Modification Recorded				Post-Modification Recorded				Charge-offs and
		Loans			Investment				Investment				Specific Reserves
Performing:
Indirect vehicle		1			$	5			$	5			$	—
Home equity		3			1,039				1,039				—
Total		4			$	1,044			$	1,044			$	—
Non-Performing:
Residential real estate		4			$	1,439			$	1,439			$	—
Indirect vehicle		18			108				108				—
Home equity		4			532				532				—
Total		26			$	2,079			$	2,079			$	—
Of the troubled debt restructurings entered into during the past twelve months, $224 thousand subsequently defaulted during the three months ended March 31, 2015.  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, 2015 (in thousands):
		Performing				Non-performing
Beginning balance		$	15,603			$	25,771
Additions		2,346				807
Charge-offs		—				(203		)
Principal payments, net		(111		)		(619		)
Removals		(1,185		)		(22		)
Transfer from/to performing		221				—
Transfer from/to non-performing		—				(221		)
Ending balance		$	16,874			$	25,513
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, 2015 (in thousands):
	31-Mar-15
	Extended
	Maturity,				Delay in
	Amortization				Payments or
	and Reduction				Reduction of
	of Interest Rate				Interest Rate				Total
Indirect vehicle	$	—			$	9			$	9
Home equity	791				2,353				3,144
Total	$	791			$	2,362			$	3,153
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, 2015 and 2014 (in thousands):
		Commercial				Commercial				Commercial				Residential			Construction			Indirect		Home			Other consumer		Unfunded			Total
						collateralized  by				real estate				real estate			real estate			vehicle		equity					commitments
						assignment of
						lease payments
31-Mar-15
Allowance for credit losses:
Three Months Ended
Beginning balance		$	29,571			$	9,962			$	41,826			$	6,646		$	8,918		$	1,687	$	9,456		$	1,960	$	4,031		$	114,057
Charge-offs		569				—				2,034				579			3			874		444			424		—			4,927
Recoveries		242				749				1,375				72			2			475		101			69		—			3,085
Provision		3,583				(886		)		791				621			556			427		(333		)	469		(254		)	4,974
Ending balance		$	32,827			$	9,825			$	41,958			$	6,760		$	9,473		$	1,715	$	8,780		$	2,074	$	3,777		$	117,189
Ending allowance balance attributable to loans:
Individually evaluated for impairment		$	2,051			$	1,534			$	1,911			$	3,045		$	162		$	14	$	2,348		$	—	$	1,333		$	12,398
Collectively evaluated for impairment		30,320				8,291				39,435				3,715			9,305			1,701		6,432			2,074		2,444			103,717
Acquired and accounted for under ASC 310-30 (1)		456				—				612				—			6			—		—			—		—			1,074
Total ending allowance balance		$	32,827			$	9,825			$	41,958			$	6,760		$	9,473		$	1,715	$	8,780		$	2,074	$	3,777		$	117,189
Loans:
Individually evaluated for impairment		$	15,389			$	3,653			$	36,152			$	15,123		$	337		$	164	$	27,979		$	—	$	—		$	98,797
Collectively evaluated for impairment		3,243,263				1,624,378				2,489,488				490,435			183,768			272,941		213,099			77,645		—			8,595,017
Acquired and accounted for under ASC 310-30 (1)		84,564				—				75,008				19,265			28,801			—		75			19,801		—			227,514
Total ending loans balance		$	3,343,216			$	1,628,031			$	2,600,648			$	524,823		$	212,906		$	273,105	$	241,153		$	97,446	$	—		$	8,921,328
31-Mar-14
Allowance for credit losses:
Three Months Ended
Beginning balance		$	23,461			$	9,159			$	51,628			$	8,872		$	6,856		$	1,662	$	8,478		$	1,630	$	1,716		$	113,462
Charge-offs		90				—				7,156				265			56			920		619			495		—			9,601
Recoveries		1,628				—				485				519			99			442		133			78		—			3,384
Provision		(1,061		)		(101		)		2,583				(1,039		)	(415		)	500		405			351		(73		)	1,150
Ending balance		$	23,938			$	9,058			$	47,540			$	8,087		$	6,484		$	1,684	$	8,397		$	1,564	$	1,643		$	108,395
Ending allowance balance attributable to loans:
Individually evaluated for impairment		$	6,160			$	174			$	4,151			$	3,076		$	195		$	25	$	1,395		$	—	$	665		$	15,841
Collectively evaluated for impairment		17,312				8,884				41,707				5,011			6,229			1,659		7,002			1,564		978			90,346
Acquired and accounted for under ASC 310-30 (1)		466				—				1,682				—			60			—		—			—		—			2,208
Total ending allowance balance		$	23,938			$	9,058			$	47,540			$	8,087		$	6,484		$	1,684	$	8,397		$	1,564	$	1,643		$	108,395
Loans:
Individually evaluated for impairment		$	41,191			$	4,235			$	57,960			$	18,151		$	782		$	183	$	24,810		$	—	$	—		$	147,312
Collectively evaluated for impairment		1,208,639				1,468,386				1,565,549				287,790			132,215			265,861		233,310			64,812		—			5,226,562
Acquired and accounted for under ASC 310-30 (1)		30,976				—				95,506				5,121			36,752			—		110			25,976		—			194,441
Total ending loans balance		$	1,280,806			$	1,472,621			$	1,719,015			$	311,062		$	169,749		$	266,044	$	258,230		$	90,788	$	—		$	5,568,315
(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 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 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 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 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 (computed on a loan by loan basis) and the principal outstanding is accreted over the remaining life of the loans. We anticipate recording a provision for the acquired portfolio in future quarters related to renewing Taylor loans which will largely offset the accretion from the pass rated loans.
In accordance with ASC 310-30, for both purchased non-impaired loans and purchased credit-impaired loans, 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 when there is a reasonable expectation about the amount and timing of such cash flows.
Substantially all of the loans acquired in transactions with the FDIC 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, 2015, there was a negative provision for credit losses of $429 thousand and net recoveries of $220 thousand, in relation to 16 pools of purchased loans with a total carrying amount of $71.7 million as of March 31, 2015. There was $1.1 million and $1.3 million in allowance for loan losses related to these purchased loans at March 31, 2015 and December 31, 2014, 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, 2015 and 2014 (in thousands):
		Three Months Ended
		March 31,
		2015				2014
Balance at beginning of period		$	7,434			$	2,337
Accretion		(1,930		)		(550		)
Other		863				574
Balance at end of period		$	6,367			$	2,361
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.
When cash flow estimates are adjusted downward for a particular loan pool, the FDIC indemnification asset is increased. An allowance for loan and lease losses is established for the impairment of the loans. A provision for credit losses is recognized for the difference between the increase in the FDIC indemnification asset and the decrease in cash flows.
When cash flow estimates are adjusted upward for a particular loan pool, the FDIC indemnification asset is decreased. The difference between the decrease in the FDIC indemnification asset and the increase in cash flows is accreted over the estimated life of the loan pool.
When cash flow estimates are adjusted downward for covered foreclosed real estate, the FDIC indemnification asset is increased. A charge is recognized for the difference between the increase in the FDIC indemnification asset and the decrease in cash flows.
When cash flow estimates are adjusted upward for covered foreclosed real estate, the FDIC indemnification asset is decreased. Any write-down after the transfer to covered foreclosed real estate is reversed.
In both scenarios, the clawback liability (the amount the FDIC requires the Company to pay back if certain thresholds are met) will increase or decrease accordingly.
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 type are as follows (in thousands):
31-Mar-15		Purchased				Purchased Non-Credit-Impaired				Total
		Credit-Impaired				Loans
		Loans
Covered loans:
Commercial related (1)		$	139			$	4			$	143
Commercial		837				273				1,110
Commercial real estate		19,570				13,669				33,239
Construction real estate		—				1,269				1,269
Other		1,134				19,794				20,928
Total covered loans		$	21,680			$	35,009			$	56,689
Estimated (payable) receivable amount from the FDIC under the loss-share agreement (2)		$	482			$	4,125			$	4,607
Non-covered loans:
Commercial related (1)		$	7,033			$	11,495			$	18,528
Commercial loans		76,279				1,285,210				1,361,489
Commercial loans collateralized by assignment of lease payments		—				114,829				114,829
Commercial real estate		41,769				840,863				882,632
Construction real estate		27,532				89,200				116,732
Other		18,212				198,740				216,952
Total non-covered loans		$	170,825			$	2,540,337			$	2,711,162
(1)	Commercial related loans include commercial, commercial real estate and construction real estate for the InBank, Heritage and Benchmark FDIC-assisted transactions.
(2)	Estimated reimbursable amounts from the FDIC under the loss-share agreement exclude $1.3 million in amounts due to the FDIC related to covered other real estate owned.
Outstanding balances on purchased loans from the FDIC were $86.5 million and $95.1 million as of March 31, 2015 and December 31, 2014, respectively.  The related carrying amount on loans purchased from the FDIC was $81.6 million and $91.4 million as of March 31, 2015 and December 31, 2014, respectively.
Effective April 1, 2014, the losses on commercial related loans (commercial, commercial real estate and construction real estate) acquired in connection with the Heritage FDIC-assisted transaction ceased being covered under the loss-share agreement for that transaction. The carrying amount of those loans was $3.0 million as of March 31, 2015. Any recoveries, net of expenses, received on commercial related loans on which losses were incurred prior to April 1, 2014 will continue to be covered (and any such net recoveries must be shared with the FDIC in accordance with the loss-share agreement) through March 31, 2017. The losses on consumer related loans acquired in connection with the Heritage FDIC-assisted transaction will continue to be covered under the loss-share agreement through March 31, 2019.
The losses on commercial related loans acquired in connection with the Benchmark FDIC-assisted transaction ceased to be covered under the loss-share agreement for that transaction effective January 1, 2015. The carrying amount of those loans was $2.8 million as of March 31, 2015. Any recoveries, net of expenses, received on commercial related loans on which losses were incurred prior to January 1, 2015 will continue to be covered (and any such net recoveries must be shared with the FDIC in accordance with the loss-share agreements) through December 31, 2017. The losses on consumer related loans acquired in connection with the Benchmark FDIC-assisted transaction will continue to be covered under the loss-share agreements through December 31, 2019.
Effective July 1, 2015, the losses on commercial related loans acquired in connection with Broadway and New Century FDIC-assisted transactions will cease to be covered under the loss-share agreements for those transactions. Any recoveries, net of expenses, received on commercial related loans on which losses were incurred prior to July 1, 2015 will continue to be covered (and any such net recoveries must be shared with the FDIC in accordance with the loss-share agreements) through June 30, 2018. The losses on consumer related loans acquired in connection with the Broadway and New Century FDIC-assisted transactions will continue to be covered under the loss-share agreements through June 30, 2020.

Goodwill_and_Intangibles

Goodwill and Intangibles	3 Months Ended
	Mar. 31, 2015
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, 2015 or 2014.   The carrying amount of goodwill was $711.5 million at March 31, 2015 and December 31, 2014.
	The Company has other intangible assets consisting of core deposit and client relationship intangibles that had a remaining weighted average amortization period of approximately five years as of March 31, 2015.
	The following table presents the changes in the carrying amount of core deposit and client relationship intangibles, gross carrying amount, accumulated amortization, and net book value as of March 31, 2015 (in thousands):
		Three Months Ended
		March 31, 2015
	Balance at beginning of period	$	38,006
	Amortization expense	(1,518		)
	Balance at end of period	$	36,488
	Gross carrying amount	$	80,371
	Accumulated amortization	(43,883		)
	Net book value	$	36,488
	The following presents the estimated future amortization expense of other intangible assets (in thousands):
	Year ending December 31,	Amount
	2015	$	4,445
	2016	5,157
	2017	4,637
	2018	4,221
	2019	2,743
	Thereafter	15,285
		$	36,488

Deposits

Deposits	3 Months Ended
	Mar. 31, 2015
Deposits [Abstract]
Deposits	Deposits
	The composition of deposits was as follows (in thousands):
		March 31,		December 31,
		2015		2014
	Demand deposit accounts, noninterest bearing	$	4,290,499	$	4,118,256
	NOW and money market accounts	4,002,818		3,913,765
	Savings accounts	969,560		940,345
	Certificates of deposit, $250,000 or more	716,701		838,928
	Other certificates of deposit	1,039,923		1,179,648
	Total	$	11,019,501	$	10,990,942
	Certificates of deposit of $250,000 or more included $395.3 million and $485.3 million of brokered deposits at March 31, 2015 and December 31, 2014, respectively.  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.

ShortTerm_Borrowings

Short-Term Borrowings	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Short-Term Borrowings	Short-Term Borrowings
	Short-term borrowings were as follows as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		31-Mar-15				31-Dec-14
		Weighted Average Cost		Amount		Weighted Average Cost		Amount
	Customer repurchase agreements	0.16	%	$	240,478	0.21	%	$	219,824
	Federal Home Loan Bank advances	0.11		300,000		0.13		700,000
	Federal funds purchased	0.33		74,753		0.14		11,591
		0.16	%	$	615,231	0.15	%	$	931,415
	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 had Federal Home Loan Bank fixed rate advances with a maturity date less than one year of $300.0 million and $700.0 million at March 31, 2015 and December 31, 2014, respectively. At March 31, 2015, the interest rate on the advance outstanding on that date had a rate of 0.11% with a maturity of December 11, 2015. The Company has investment securities available for sale and loans pledged as collateral on this FHLB advance. See Note 5. Investment Securities and Note 6. Loans of the notes to the consolidated financial statements.
	On March 9, 2012, the Company entered into a $35.0 million unsecured line of credit with a correspondent bank. Interest is payable at a rate of one month LIBOR + 1.85%. As of March 31, 2015, no amount was outstanding and the line of credit is scheduled to mature on September 7, 2015.

Longterm_Borrowings

Long-term Borrowings	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Long-term Borrowings	Long-term Borrowings
	The Company had Federal Home Loan Bank advances with remaining contractual maturities greater than one year of $4.1 million at March 31, 2015 and $4.2 million at December 31, 2014. As of March 31, 2015, the advances had fixed terms with effective interest rates, net of discounts, ranging from 3.23% to 5.87% and maturities ranging from April 2021 to April 2035. The Company has investment securities available for sale and loans pledged as collateral on these FHLB advances. See Note 5. Investment Securities and Note 6. Loans of the notes to the consolidated financial statements.
	The Company had notes payable to banks totaling $41.2 million and $38.5 million at March 31, 2015 and December 31, 2014, respectively, which as of March 31, 2015, were accruing interest at rates ranging from 2.25% to 12.00%.  Lease investments includes equipment with an amortized cost of $50.8 million and $48.8 million at March 31, 2015 and December 31, 2014, respectively, that is pledged as collateral on these notes.
	The Company had a $40.0 million 10-year structured repurchase agreement as of March 31, 2015 and December 31, 2014, which bears interest at a fixed rate borrowing of 4.75% and expires in 2016.

Junior_Subordinated_Notes_Issu

Junior Subordinated Notes Issued to Capital Trusts	3 Months Ended
	Mar. 31, 2015
JUNIOR SUBORDINATED NOTES ISSUED TO CAPITAL TRUSTS
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 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, 2015 (in thousands):
			Coal City		MB Financial		MB Financial		MB Financial
			Capital Trust I		Capital Trust II		Capital Trust III		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		MB Financial		FOBB		TAYC
			Capital Trust V		Capital Trust VI		Statutory Trust III (2)		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
	-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 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 discount of $7.4 million.
	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.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
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, 2015 and December 31, 2014, the following financial instruments were outstanding, the contractual amounts of which represent off-balance sheet credit risk (in thousands):
		Contractual Amount
		March 31, 2015		December 31, 2014
	Commitments to extend credit:
	Home equity lines	$	209,466	$	221,102
	Other commitments	2,651,028		2,643,220
	Letters of credit:
	Standby	132,056		131,810
	Commercial	5,992		2,401
	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, 2015, the maximum remaining term for any standby letters of credit was September 30, 2030.  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, 2015, 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, increased $3.8 million to $138.0 million from $134.2 million at December 31, 2014.  Of the $138.0 million in commitments outstanding at March 31, 2015, approximately $32.2 million of the letters of credit have been issued or renewed since December 31, 2014.
	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, 2015, the Company had approximately $2.6 million in capital expenditure commitments outstanding which relate to various projects to renovate existing branches.
	Concentrations of credit risk:  The majority of the loans, commitments to extend credit and standby letters of credit have been granted to customers in the Company’s market area.  As of March 31, 2015, approximately 25% 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, 2015. The distribution of commitments to extend credit approximates the distribution of loans outstanding.  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.
	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, 2015
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 a 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.
	Loans Held for Sale. Residential real estate 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.
	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.
	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 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.
	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.
	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. We also obtain dealer quotations for these derivatives for comparative purposes to assess the reasonableness of the model valuations. In addition, we use 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. We also offer 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 which 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 following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of March 31, 2015 and December 31, 2014, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands):
			Total				Quoted Prices in				Significant Other				Significant
							Active Markets for				Observable Inputs				Unobservable Inputs
							Identical Assets				(Level 2)				(Level 3)
							(Level 1)
	31-Mar-15
	Financial assets
	Securities available for sale:
	U.S Government sponsored agencies and enterprises		$	66,070			$	—			$	66,070			$	—
	States and political subdivisions		403,628				—				403,165				463
	Residential mortgage-backed securities		678,475				—				678,003				472
	Commercial mortgage-backed securities		178,458				—				178,458				—
	Corporate bonds		252,042				—				252,042				—
	Equity securities		10,751				10,751				—				—
	Loans held for sale		686,838				—				686,838				—
	Loans		20,829				—				20,829				—
	Mortgage servicing rights		219,254				—				—				219,254
	Assets held in trust for deferred compensation		18,087				18,087				—				—
	Derivative financial instruments		68,283				6,427				50,642				11,214
	Financial liabilities
	Other liabilities (1)		17,633				17,633				—				—
	Derivative financial instruments		47,162				8,235				38,927				—
	31-Dec-14
	Financial assets
	Securities available for sale:
	U.S. Government sponsored agencies and enterprises		$	65,873			$	—			$	65,873			$	—
	States and political subdivisions		410,854				—				410,391				463
	Residential mortgage-backed securities		720,563				—				720,053				510
	Commercial mortgage-backed securities		187,662				—				187,662				—
	Corporate bonds		259,203				—				259,203				—
	Equity securities		10,597				10,597				—				—
	Loans held for sale		737,209				—				737,209				—
	Mortgage servicing rights		235,402				—				—				235,402
	Assets held in trust for deferred compensation		16,829				16,829				—				—
	Derivative financial instruments		46,388				1,607				39,707				5,074
	Financial liabilities
	Other liabilities (1)		16,483				16,483				—				—
	Derivative financial instruments		40,499				7,209				33,290				—
	(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 at
		March 31, 2015				Valuation Technique		Unobservable Input		Range
		(in thousands)
	States and political subdivisions	$	463			Discounted cash flows		Credit assumption		45% Loss
	Residential mortgage-backed securities	472				Discounted cash flows		Constant pre-payment rates (CPR)		1% - 3%
	Mortgage servicing rights	219,254				Discounted cash flows		CPR		10.4% - 14.2%
								Discount rate		9.25 - 12.00
								Maturity (months)		299 - 356
								Delinquencies		0.25 - 5.00
							Costs to service		$ 60 - $ 160
							Costs to service - delinquent		$ 100 - $ 1,000
Derivative financial instruments (mortgage	11,214				Sales cash flows		Expected closing ratio		65% - 95%
interest rate lock commitments)							Expected delivery price		98.86 bps - 108.93 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, 2015 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)	31-Mar-15
Weighted average CPR	13.6		%
Impact on fair value of 10% adverse change	$	(9,979	)
Impact on fair value of 20% adverse change	(19,144		)
Weighted average discount rate	9.42		%
Impact on fair value of 10% adverse change	$	(7,330	)
Impact on fair value of 20% adverse change	(14,193		)
Weighted average delinquency rate	0.98		%
Impact on fair value of 10% adverse change	$	(1,310	)
Impact on fair value of 20% adverse change	(1,977		)
Weighted average costs to service	$	70
Impact on fair value of 10% adverse change	(3,142		)
Impact on fair value of 20% adverse change	(6,284		)
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, 2015. 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,
		2015				2014				2015				2014			2015		2014
(in thousands)		Investment Securities								Mortgage Servicing Rights							Derivatives
Balance, beginning of period		$	973			$	5,856			$	235,402			$	—		$	5,074	$	—
Purchases		—				—				85				—			—		—
Originations		—				—				16,560				—			—		—
Other comprehensive income		—				(179		)		—				—			—		—
Included in earnings		—				—				(32,793		)		—			6,140		—
Principal payments		(38		)		(178		)		—				—			—		—
Balance, ending of period		$	935			$	5,499			$	219,254			$	—		$	11,214	$	—
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 (90% at March 31, 2015), 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, 2015 and December 31, 2014 are included in the table below (in thousands):
		Total				Quoted Prices in Active				Significant Other				Significant
						Markets for Identical				Observable Inputs				Unobservable Inputs
						Assets (Level 1)				(Level 2)				(Level 3)
31-Mar-15
Financial assets:
Impaired loans		$	61,757			$	—			$	—			$	61,757
Non-financial assets:
Foreclosed assets		39,889				—				—				39,889
31-Dec-14
Financial assets:
Impaired loans		$	61,717			$	—			$	—			$	61,717
Non-financial assets:
Foreclosed assets		38,619				—				—				38,619
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 at			Valuation	Unobservable
	March 31, 2015			Technique	Input	Range
	(in thousands)
Impaired loans	$	61,757		Appraisal of collateral	Appraisal adjustments - sales costs	5% - 10%
Foreclosed assets	39,889			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 following methods and assumptions were used by the Company in estimating the fair values of its other financial instruments:
Cash and due from banks, interest earning deposits with banks and federal funds sold: 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 a 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. 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.
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):
		31-Mar-15
		Carrying Amount				Estimated Fair Value			Quoted Prices in Active			Significant Other			Significant
									Markets for Identical			Observable Inputs			Unobservable Inputs
									Assets (Level 1)			(Level 2)			(Level 3)
Financial Assets:
Cash and due from banks		$	248,840			$	248,840		$	248,840		$	—		$	—
Interest earning deposits with banks		52,212				52,212			52,212			—			—
Investment securities available for sale		1,589,424				1,589,424			10,751			1,577,738			935
Investment securities held to maturity		1,000,859				1,045,205			—			1,045,205			—
Non-marketable securities - FHLB and FRB stock		87,677				87,677			—			—			87,677
Loans held for sale		686,838				686,838			—			686,838			—
Loans, net		8,807,916				8,870,489			—			20,829			8,849,660
Accrued interest receivable		46,532				46,532			46,532			—			—
Derivative financial instruments		68,283				68,283			6,427			50,642			11,214
Financial Liabilities:
Noninterest bearing deposits		$	4,290,499			$	4,290,499		$	4,290,499		$	—		$	—
Interest bearing deposits		6,729,002				6,734,854			—			—			6,734,854
Short-term borrowings		615,231				615,216			—			—			615,216
Long-term borrowings		85,477				88,299			—			—			88,299
Junior subordinated notes issued to capital trusts		185,874				123,059			—			—			123,059
Accrued interest payable		3,005				3,005			3,005			—			—
Derivative financial instruments		47,162				47,162			8,235			38,927			—
		31-Dec-14
		Carrying Amount				Estimated Fair Value			Quoted Prices in Active			Significant Other			Significant
									Markets for Identical			Observable Inputs			Unobservable Inputs
									Assets (Level 1)			(Level 2)			(Level 3)
Financial Assets:
Cash and due from banks		$	256,804			$	256,804		$	256,804		$	—		$	—
Interest earning deposits with banks		55,277				55,277			55,277			—			—
Investment securities available for sale		1,654,752				1,654,752			10,597			1,643,182			973
Investment securities held to maturity		993,380				1,035,061			—			1,035,061			—
Non-marketable securities - FHLB and FRB stock		75,569				75,569			—			—			75,569
Loans held for sale		737,209				737,209			—			737,209			—
Loans, net		8,973,191				8,956,494			—			—			8,956,494
Accrued interest receivable		49,065				49,065			49,065			—			—
Derivative financial instruments		46,388				46,388			1,607			39,707			5,074
Financial Liabilities:
Non-interest bearing deposits		$	4,118,256			$	4,118,256		$	4,118,256		$	—		$	—
Interest bearing deposits		6,872,686				6,877,349			—			—			6,877,349
Short-term borrowings		931,415				931,415			—			—			931,415
Long-term borrowings		82,916				86,025			—			—			86,025
Junior subordinated notes issued to capital trusts		185,778				122,408			—			—			122,408
Accrued interest payable		3,709				3,709			3,709			—			—
Derivative financial instruments		40,499				40,499			7,209			33,290			—

Stock_Incentive_Plans

Stock Incentive Plans	3 Months Ended
	Mar. 31, 2015
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,
		2015				2014
	Total cost of share-based payment plans during the period	$	3,605			$	2,012
	Amount of related income tax benefit recognized in income	1,412				$	790
	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. Following May 28, 2014, no more than 10% of the total number of authorized shares may be issued with respect to awards granted after that date, 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, 2015, there were 4,979,712 shares available for future grants.
	Prior to 2014, annual equity-based incentive awards were typically granted to selected officers and employees mid-year. In 2014, these awards began being granted 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 stock options outstanding for the three months ended March 31, 2015:
		Number of			Weighted			Weighted	Aggregate
		Options			Average			Average	Intrinsic
					Exercise			Remaining	Value
					Price			Contractual	(in thousands)
								Term
								(In Years)
	Options outstanding as of December 31, 2014	2,250,714			$	27.94		4.39
	Granted	296,413			31.26
	Exercised	(7,284	)		19.85
	Expired or cancelled	(3,933	)		30.34
	Forfeited	(2,928	)		25
	Options outstanding as of March 31, 2015	2,532,982			$	28.35		4.81	$	11,342
	Options exercisable as of March 31, 2015	1,729,575			$	29.07		3.12	$	7,723
	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, 2015:
		March 31, 2015
	Risk-free interest rate	1.71		%
	Expected volatility of Company’s stock	30.43		%
	Expected dividend yield	1.79		%
	Expected life of options	5.9 years
	Weighted average fair value per option of options granted during the year	$	8.08
	The total intrinsic value of options exercised during the three months ended March 31, 2015 and 2014 was $81 thousand and $550 thousand, respectively.
	The following is a summary of changes in restricted shares and units for the three months ended March 31, 2015:
		Number of			Weighted
		Shares and Units			Average
					Grant Date
					Fair Value
	Shares Outstanding at December 31, 2014	801,085			$	26.99
	Granted	490,504			31.65
	Vested	(94,740	)		27.74
	Forfeited	(3,539	)		27.08
	Shares Outstanding at March 31, 2015	1,193,310			$	28.85
	The total intrinsic value of restricted shares that vested during the three months ended March 31, 2015 and 2014 was $3.0 million and $1.0 million, respectively.
	The Company issued 71,560, 48,569, 56,752 and 65,333 market-based restricted stock units in 2015, 2014, 2013 and 2012, 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 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 of issuance.
	As of March 31, 2015, there was $31.6 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, 2015, the weighted-average period over which the unrecognized compensation expense is expected to be recognized was approximately 2.7 years.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2015
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 our 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, 2015 was approximately $3 thousand, and the net amount payable as of December 31, 2014 was approximately $1.1 million.  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, 2015, the Company’s credit exposure relating to interest rate swaps was approximately $33.7 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 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 $187 thousand at March 31, 2015.  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 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 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, 2015 and December 31, 2014 (in thousands):
		Asset Derivatives										Liability Derivatives
		31-Mar-15						31-Dec-14				31-Mar-15					31-Dec-14
		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)	$	—		$	—		$	—	$	—	$	187	$	(14	)	$	197		$	(15	)
	Stand-alone derivative instruments: (2)
	Interest rate swap contracts	2,072,809			50,633			1,509,930		37,039		1,268,604		(34,942		)	2,001,787			(30,761		)
	Interest rate options contracts	617,089			982			55,830		283		67,089		(260		)	55,830			(283		)
	Foreign exchange contracts	49,017			4,470			27,402		2,276		46,904		(4,181		)	27,002			(2,109		)
	Spot foreign exchange contracts	210			6			512		5		462		(46		)	304			(18		)
	Mortgage related derivatives	955,583			12,192			871,446		6,785		1,271,000		(7,719		)	879,841			(7,313		)
	Total non-hedging derivative instruments	3,694,708			68,283			2,465,120		46,388		2,654,059		(47,148		)	2,964,764			(40,484		)
	Total	$	3,694,708		$	68,283		$	2,465,120	$	46,388	$	2,654,246	$	(47,162	)	$	2,964,961		$	(40,499	)
	(1) Hedged fixed-rate commercial real estate loans
	(2) These portfolio swaps are not designated as hedging instruments under ASC Topic 815.
	Amounts included in the other income in the consolidated statements of operations related to derivative financial instruments were as follows (in thousands):
		Three Months Ended
		March 31,
		2015			2014
	Derivative instruments designated as hedges of fair value:
	Interest rate swap contracts	$	1		$	—
	Stand-alone derivative instruments:
	Interest rate swap contracts	11,125			9
	Interest rate options contracts	723			—
	Foreign exchange contracts	122			61
	Spot foreign exchange contracts	(28		)	8
	Mortgage related derivatives	908			3
	Total non-hedging derivative instruments	12,850			81
	Total	$	12,851		$	81
	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, 2015 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 swaps, caps and floors	$	17,959		$	—		$	17,959	$	34,795	$	—	$	34,795
	Foreign currency forward contracts	2,307			—			2,307		2,050		—		2,050
	Mortgage related derivatives	1,394			—			1,394		8,134		—		8,134
	Total derivatives	21,660			—			21,660		44,979		—		44,979
	Repurchase agreements	—			—			—		240,478		—		240,478
	Total	$	21,660		$	—		$	21,660	$	285,457	$	—	$	285,457
		Financial Assets										Financial Liabilities
		Net Amount Recognized			Financial Instruments			Collateral		Net Amount		Net Amount Recognized		Financial Instruments			Collateral			Net Amount
	Derivatives:
	Counterparty A	$	19		$	(19	)	$	—	$	—	$	10,604	$	(19	)	$	(10,585	)	$	—
	Counterparty B	27			(27		)	—		—		4,962		(27		)	(4,935		)	—
	Counterparty C	9,792			(9,792		)	—		—		13,218		(9,792		)	(3,426		)	—
	Other counterparties	11,822			(6,917		)	—		4,905		16,195		(6,918		)	(7,745		)	1,532
	Total derivatives	21,660			(16,755		)	—		4,905		44,979		(16,756		)	(26,691		)	1,532
	Repurchase agreements	—			—			—		—		240,478		—			(240,478		)	—
	Total	$	21,660		$	(16,755	)	$	—	$	4,905	$	285,457	$	(16,756	)	$	(267,169	)	$	1,532
	Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2014 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 swaps, caps and floors	$	10,727		$	—		$	10,727	$	29,916	$	—	$	29,916
Foreign currency forward contracts	1,525			—			1,525		709		—		709
Mortgage related derivatives	1,700			—			1,700		7,302		—		7,302
Total derivatives	13,952			—			13,952		37,927		—		37,927
Repurchase agreements	—			—			—		219,824		—		219,824
Total	$	13,952		$	—		$	13,952	$	257,751	$	—	$	257,751
	Financial Assets										Financial Liabilities
	Net Amount Recognized			Financial Instruments			Collateral		Net Amount		Net Amount Recognized		Financial Instruments			Collateral			Net Amount
Derivatives:
Counterparty A	$	13		$	(13	)	$	—	$	—	$	9,556	$	(13	)	$	(9,543	)	$	—
Counterparty B	145			(145		)	—		—		3,736		(145		)	(3,591		)	—
Counterparty C	6,123			(6,123		)	—		—		10,335		(6,122		)	(4,213		)	—
Other counterparties	7,671			(3,920		)	—		3,751		14,300		(3,920		)	(8,663		)	1,717
Total derivatives	13,952			(10,201		)	—		3,751		37,927		(10,200		)	(26,010		)	1,717
Repurchase agreements	—			—			—		—		219,824		—			(219,824		)	—
Total	$	13,952		$	(10,201	)	$	—	$	3,751	$	257,751	$	(10,200	)	$	(245,834	)	$	1,717

Operating_Segments

Operating Segments	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Operating Segments	Operating Segments
	The Company's operations 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 and deposit gathering 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 dependent on changes in its 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 customers and depositors.  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 offered through the Company's leasing subsidiaries, LaSalle Systems Leasing, Inc., Celtic Leasing Corp. and Cole Taylor Equipment Finance, LLC. The leasing subsidiaries invest directly in equipment that we lease (referred to as direct finance, leveraged or operating leases) to "Fortune 1000," large middle-market companies and healthcare 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 subsidiaries also specialize in selling third party equipment maintenance contracts to large companies.
	The mortgage banking segment originates mortgage loans for sale to investors and for the Company's portfolio through its retail and broker channels. This segment also services residential mortgage loans for various investors and for loans owned by the Company. The mortgage banking segment is also subject to an extensive system of laws and regulations that are intended primarily for the protection of customers.
	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, 2015
	Net interest income	$	104,126	$	3,015	$	6,254		$	113,395
	Provision for credit losses	4,974		—		—			4,974
	Non-interest income	31,517		25,203		24,548			81,268
	Non-interest expense (1)	95,334		13,656		30,930			139,920
	Income tax expense	9,962		5,747		(51		)	15,658
	Net income	$	25,373	$	8,815	$	(77	)	$	34,111
	Total assets	$	12,246,659	$	937,903	$	1,143,748		$	14,328,310
	Three months ended March 31, 2014
	Net interest income	$	66,324	$	1,004	$	—		$	67,328
	Provision for credit losses	1,150		—		—			1,150
	Non-interest income	23,701		12,852		59			36,612
	Non-interest expense	68,334		7,713		—			76,047
	Income tax expense	4,483		2,291		—			6,774
	Net income	$	16,058	$	3,852	$	59		$	19,969
	Total assets	$	8,968,195	$	469,108	$	—		$	9,437,303
	(1)	Includes merger related expenses of $8.1 million and $680 thousand in the banking segment for the three months ended March 31, 2015 and 2014, respectively.

Preferred_Stock

Preferred Stock	3 Months Ended
	Mar. 31, 2015
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 are 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 is $25 per share, at a rate of 8.00% per annum, payable quarterly. The Company Series A Preferred Stock is included in Tier 1 capital for regulatory capital purposes.

New_Authoritative_Accounting_G1

New Authoritative Accounting Guidance (Policies)	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Authoritative Accounting Pronouncements	New Authoritative Accounting Guidance
	ASC Topic 310 “Receivables.” New authoritative accounting guidance under ASC Topic 310, “Receivables” amended prior guidance to clarify that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical
	possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additionally, the amendments require interim and annual disclosures. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	New authoritative accounting guidance under ASC Topic 310, “Receivables” amended prior guidance to require an entity to derecognize a mortgage loan and recognize a separate other receivable upon foreclosure if (i) the loan has a government guarantee that is not separable from the loan before foreclosure, (ii) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on that guarantee, and the creditor has the ability to recover under that claim, and (iii) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. The separate other receivable is to be measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have a material impact on the Company's statements of operations or financial condition.
	ASC Topic 323 “Investments - Equity Method and Joint Ventures.” New authoritative accounting guidance under ASC Topic 323, “Investments - Equity Method and Joint Ventures” amended prior guidance to permit entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the statement of operation as a component of income tax expense. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	ASC Topics 205 “Presentation of Financial Statements” and 360 “Property, Plant, and Equipment.” New authoritative accounting guidance under ASC Topic 205, “Presentation of Financial Statements” and ASC Topic 360 “Property, Plant, and Equipment” amended prior guidance to change the requirements for reporting discontinued operations. The disposal of a component of an entity or group of components of an entity is required to be reported in discontinued operations if the disposal represents a strategic shift that has (or will have) a major effect on an entity's operations and financial results. The new authoritative guidance also requires additional disclosures about discontinued operations. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	ASC Topic 860 “Transfers and Servicing.” New authoritative accounting guidance under ASC Topic 860, “Transfers and Servicing” amended prior guidance to change the accounting for repurchase-to-maturity transactions to secured borrowing accounting and to require separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. The new authoritative guidance also requires disclosures for a transfer of a financial asset accounted for as a sale and an agreement with the same transferee entered into in contemplation of the initial transfer that results in the transferor retaining substantially all of the exposure to the economic return on the transferred financial asset throughout the term of the transaction. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an 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” amended prior guidance to require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. The Company adopted this new authoritative guidance on January 1, 2015, and it did not have an impact on the Company's statements of operations or financial condition.
	ASC Topic 225 “Income Statement - Extraordinary and Unusual Items.” New authoritative accounting guidance under ASC Topic 225, “Income Statement - Extraordinary and Unusual Items” amended prior guidance to eliminate the concept of extraordinary items. The new authoritative guidance will be effective for reporting periods after January 1, 2016 and is not expected to have a significant impact on the Company's statements of operations or financial condition.
	ASC Topic 810 “Consolidation.” New authoritative accounting guidance under ASC Topic 810, “Consolidation” amended prior guidance over the consolidation of certain legal entities. The new authoritative guidance modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership, affects the consolidation analysis of reporting entities that are involved with variable interest entities and provides a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements similar to those for registered money market funds. The new authoritative guidance will be effective for reporting periods after January 1, 2016 and is not expected to have a significant impact on the Company's statements of operations or financial condition.

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Reconciliation of the number of shares used in the calculation of basic and diluted earnings (loss) per common share, net income available to common stockholders, and earnings per 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,
		2015		2014
	Distributed earnings allocated to common stock	$	10,610	$	6,666
	Undistributed earnings	23,501		13,303
	Net income	34,111		19,969
	Less: preferred stock dividends	2,000		—
	Net income available to common stockholders	32,111		19,969
	Less: earnings allocated to participating securities	1		—
	Earnings allocated to common stockholders	$	32,110	$	19,969
	Weighted average shares outstanding for basic earnings per common share	74,567,104		54,639,951
	Dilutive effect of equity awards	597,612		625,237
	Weighted average shares outstanding for diluted earnings per common share	75,164,716		55,265,188
	Basic earnings per common share	$	0.43	$	0.37
	Diluted earnings per common share	0.43		0.36

Business_Combinations_Tables

Business Combinations (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	Estimated fair values of the assets acquired and liabilities assumed in the Taylor Capital transaction, as of the closing date of the transaction were as follows (in thousands):
		August 18,
		2014
	ASSETS
	Cash and cash equivalents	$	154,684
	Investment securities available for sale	826,691
	Investment securities held to maturity	22,599
	Non-marketable securities - FRB and FHLB Stock	50,620
	Loans held for sale	670,671
	Loans	3,532,211
	Leases investments	11,885
	Premises and equipment	19,701
	Goodwill	288,152
	Core deposit intangible	20,079
	Mortgage servicing rights	224,453
	Other real estate owned	4,720
	Other assets	130,478
	Total assets	$	5,956,944
	LIABILITIES
	Deposits	$	3,953,213
	Short-term borrowings	1,035,800
	Junior subordinated notes issued to capital trusts	80,843
	Accrued expenses and other liabilities	123,028
	Total liabilities	$	5,192,884
	Series A preferred stock at $28.82 per share at August 15, 2014	$	115,280
	Total identifiable net assets less Series A preferred stock	$	648,780
	Consideration excluding Series A preferred stock:
	Market value of common stock at $26.49 per share at August 15, 2014 (19,602,482 shares of common stock issued)	$	519,270
	Cash paid	129,510
	Total fair value of consideration, excluding Series A preferred stock	$	648,780
	The following table presents the acquired loans as of the acquisition date (in thousands):
		PCI Loans			Non-PCI Loans
	Contractually required principal and interest payments	$	244,650		$	3,707,463
	Contractually required interest payments not expected to be collected due to estimated prepayments	—			(302,329		)
	Nonaccretable difference	(34,219		)	—
	Cash flows expected to be collected	210,431			3,405,134
	Accretable difference	(5,626		)	(77,728		)
	Fair value of acquired loans	$	204,805		$	3,327,406
Business Acquisition, Pro Forma Information	The following table provides the unaudited pro forma information for the results of operations for the three months ended March 31, 2014, as if the acquisition had occurred January 1, 2014. The pro forma results combine the historical results of Taylor Capital into the Company's consolidated statement of operations including the impact of certain purchase accounting adjustments including loan discount accretion, investment securities discount accretion, intangible assets amortization, deposit premium accretion and borrowing discount amortization. The pro forma results have been prepared for comparative purposes only and are not necessarily indicative of the results that would have been obtained had the acquisition actually occurred on January 1, 2014. No assumptions have been applied to the pro forma results of operations regarding possible revenue enhancements, provision for credit losses, expense efficiencies or asset dispositions. Net income in the table below includes merger related expenses.
		Pro Forma
		Three Months Ended
		March 31,
		2014
	(in thousands)
	Total revenues (net interest income plus non-interest income)	$	185,028
	Net income	34,752

Investment_Securities_Tables

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Summary investment holdings	Amortized cost and fair value of investment securities were as follows as of the dates indicated (in thousands):
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Gains			Losses
	31-Mar-15
	Available for Sale
	U.S. Government sponsored agencies and enterprises	$	64,411		$	1,659		$	—		$	66,070
	States and political subdivisions	381,704			21,953			(29		)	403,628
	Residential mortgage-backed securities	666,904			12,383			(812		)	678,475
	Commercial mortgage-backed securities	174,823			3,816			(181		)	178,458
	Corporate bonds	250,543			3,462			(1,963		)	252,042
	Equity securities	10,587			164			—			10,751
	Total Available for Sale	1,548,972			43,437			(2,985		)	1,589,424
	Held to Maturity
	States and political subdivisions	764,931			32,136			(284		)	796,783
	Residential mortgage-backed securities	235,928			12,494			—			248,422
	Total Held to Maturity	1,000,859			44,630			(284		)	1,045,205
	Total	$	2,549,831		$	88,067		$	(3,269	)	$	2,634,629
	31-Dec-14
	Available for Sale
	U.S. Government sponsored agencies and enterprises	$	64,612		$	1,281		$	(20	)	$	65,873
	States and political subdivisions	390,076			20,846			(68		)	410,854
	Residential mortgage-backed securities	713,413			8,977			(1,827		)	720,563
	Commercial mortgage-backed securities	186,110			1,772			(220		)	187,662
	Corporate bonds	259,526			2,428			(2,751		)	259,203
	Equity securities	10,531			66			—			10,597
	Total Available for Sale	1,624,268			35,370			(4,886		)	1,654,752
	Held to Maturity
	States and political subdivisions	752,558			30,089			(382		)	782,265
	Residential mortgage-backed securities	240,822			11,974			—			252,796
	Total Held to Maturity	993,380			42,063			(382		)	1,035,061
	Total	$	2,617,648		$	77,433		$	(5,268	)	$	2,689,813
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, 2015 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
	States and political subdivisions	$	4,761		$	(10	)	$	2,253		$	(19	)	$	7,014	$	(29	)
	Residential mortgage-backed securities	62,437			(278		)	43,263			(534		)	105,700		(812		)
	Commercial mortgage-backed securities	16,752			(181		)	—			—			16,752		(181		)
	Corporate bonds	26,242			(459		)	9,675			(1,504		)	35,917		(1,963		)
	Total Available for Sale	110,192			(928		)	55,191			(2,057		)	165,383		(2,985		)
	Held to Maturity
	States and political subdivisions	36,619			(137		)	6,240			(147		)	42,859		(284		)
	Total	$	146,811		$	(1,065	)	$	61,431		$	(2,204	)	$	208,242	$	(3,269	)
	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, 2014 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	$	9,644		$	(20	)	$	—		$	—		$	9,644	$	(20	)
	States and political subdivisions	7,784			(21		)	3,558			(47		)	11,342		(68		)
	Residential mortgage-backed securities	235,818			(1,336		)	29,373			(491		)	265,191		(1,827		)
	Commercial mortgage-backed securities	89,509			(220		)	—			—			89,509		(220		)
	Corporate bonds	62,693			(1,159		)	9,675			(1,592		)	72,368		(2,751		)
	Total Available for Sale	405,448			(2,756		)	42,606			(2,130		)	448,054		(4,886		)
	Held to Maturity
	States and political subdivisions	28,786			(130		)	14,238			(252		)	43,024		(382		)
	Total	$	434,234		$	(2,886	)	$	56,844		$	(2,382	)	$	491,078	$	(5,268	)
Summary of realized gains on the sale of investment securities available for sale	Net (losses) gains recognized on investment securities available for sale were as follows (in thousands):
		Three Months Ended
		March 31,
		2015			2014
	Realized gains	$	759		$	318
	Realized losses	(1,219		)	(1		)
	Net (losses) gains	$	(460	)	$	317
Schedule of remaining contractual maturities of securities included in the securities portfolio	The amortized cost and fair value of investment securities as of March 31, 2015 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	$	17,722		$	17,770
	Due after one year through five years	291,975			294,881
	Due after five years through ten years	42,645			44,133
	Due after ten years	344,316			364,956
	Equity securities	10,587			10,751
	Residential and commercial mortgage-backed securities	841,727			856,933
		1,548,972			1,589,424
	Held to maturity:
	Due in one year or less	52,102			52,249
	Due after one year through five years	222,670			224,797
	Due after five years through ten years	99,975			104,546
	Due after ten years	390,184			415,191
	Residential mortgage-backed securities	235,928			248,422
		1,000,859			1,045,205
	Total	$	2,549,831		$	2,634,629

Loans_Tables

Loans (Tables)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Schedule of composition of loans	Loans consist of the following at (in thousands):
			March 31,				December 31,
			2015				2014
	Commercial loans		$	3,258,652			$	3,245,206
	Commercial loans collateralized by assignment of lease payments		1,628,031				1,692,258
	Commercial real estate		2,525,640				2,544,867
	Residential real estate		505,558				503,287
	Construction real estate		184,105				247,068
	Indirect vehicle		273,105				268,840
	Home equity		241,078				251,909
	Other consumer loans		77,645				78,137
	Total loans, excluding purchased credit-impaired and covered loans		8,693,814				8,831,572
	Purchased credit-impaired and covered loans		227,514				251,645
	Total loans		$	8,921,328			$	9,083,217
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, 2015 and December 31, 2014 (in thousands):
			Current				30-59 Days				60-89 Days				Loans Past Due			Total			Total
							Past Due				Past Due				90 Days or More			Past Due
	31-Mar-15
	Commercial		$	3,220,398			$	27,393			$	1,899			$	8,962		$	38,254		$	3,258,652
	Commercial collateralized by assignment of lease payments		1,611,508				12,350				2,062				2,111			16,523			1,628,031
	Commercial real estate
	Healthcare		344,393				—				—				—			—			344,393
	Industrial		334,667				—				—				2,309			2,309			336,976
	Multifamily		372,358				2,823				—				1,336			4,159			376,517
	Retail		436,710				240				1,817				2,054			4,111			440,821
	Office		243,266				1,235				23				2,048			3,306			246,572
	Other		776,851				1,156				281				2,073			3,510			780,361
	Residential real estate		492,557				5,060				951				6,990			13,001			505,558
	Construction real estate		183,768				—				—				337			337			184,105
	Indirect vehicle		270,474				1,933				473				225			2,631			273,105
	Home equity		232,851				2,551				268				5,408			8,227			241,078
	Other consumer		77,546				76				23				—			99			77,645
	Total loans, excluding purchased credit-impaired and covered loans		8,597,347				54,817				7,797				33,853			96,467			8,693,814
	Purchased credit-impaired and covered loans		134,140				8,291				1,685				83,398			93,374			227,514
	Total loans		$	8,731,487			$	63,108			$	9,482			$	117,251		$	189,841		$	8,921,328
	Non-performing loan aging		$	45,674			$	3,018			$	911			$	33,675		$	37,604		$	83,278
	31-Dec-14
	Commercial		$	3,231,571			$	8,222			$	—			$	5,413		$	13,635		$	3,245,206
	Commercial collateralized by assignment of lease payments		1,679,991				2,025				6,095				4,147			12,267			1,692,258
	Commercial real estate
	Healthcare		342,984				—				—				—			—			342,984
	Industrial		333,907				944				—				3,182			4,126			338,033
	Multifamily		417,504				1,377				—				1,517			2,894			420,398
	Retail		432,718				2,481				652				2,325			5,458			438,176
	Office		244,166				—				—				2,127			2,127			246,293
	Other		754,031				307				2,421				2,224			4,952			758,983
	Residential real estate		485,492				8,038				2,319				7,438			17,795			503,287
	Construction real estate		246,731				—				—				337			337			247,068
	Indirect vehicle		265,296				2,516				702				326			3,544			268,840
	Home equity		242,756				2,717				1,039				5,397			9,153			251,909
	Other consumer		78,106				16				12				3			31			78,137
	Total loans, excluding purchased credit-impaired and covered loans		8,755,253				28,643				13,240				34,436			76,319			8,831,572
	Purchased credit-impaired and covered loans		158,215				4,432				585				88,413			93,430			251,645
	Total loans		$	8,913,468			$	33,075			$	13,825			$	122,849		$	169,749		$	9,083,217
	Non-performing loan aging		$	46,149			$	5,764			$	1,099			$	34,075		$	40,938		$	87,087
Recorded investment in nonaccrual 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 and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
			March 31, 2015								December 31, 2014
							Loans past due								Loans past due
			Non-accrual				90 days or more				Non-accrual				90 days or more
							and still accruing								and still accruing
	Commercial		$	13,897			$	75			$	14,088			$	—
	Commercial collateralized by assignment of lease payments		3,602				741				2,404				3,566
	Commercial real estate:
	Healthcare		—				—				—				—
	Industrial		4,816				—				6,371				—
	Multifamily		5,008				—				5,333				—
	Office		3,268				—				3,644				464
	Retail		2,898				—				2,986				—
	Other		13,655				—				13,541				324
	Residential real estate		16,925				891				17,311				—
	Construction real estate		337				—				337				—
	Indirect vehicle		1,473				—				1,542				—
	Home equity		15,672				—				15,171				—
	Other consumer		20				—				5				—
	Total		$	81,571			$	1,707			$	82,733			$	4,354
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 and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
			Pass				Special				Substandard				Doubtful			Total
							Mention
	31-Mar-15
	Commercial		$	3,029,893			$	155,032			$	73,727			$	—		$	3,258,652
	Commercial collateralized by assignment of lease payments		1,614,968				935				12,128				—			1,628,031
	Commercial real estate
	Healthcare		340,036				4,357				—				—			344,393
	Industrial		314,666				13,200				9,110				—			336,976
	Multifamily		368,675				1,287				6,555				—			376,517
	Retail		426,760				4,165				9,896				—			440,821
	Office		225,451				13,544				7,577				—			246,572
	Other		727,643				17,426				35,292				—			780,361
	Construction real estate		183,244				524				337				—			184,105
	Total		$	7,231,336			$	210,470			$	154,622			$	—		$	7,596,428
	31-Dec-14
	Commercial		$	3,036,069			$	178,984			$	30,153			$	—		$	3,245,206
	Commercial collateralized by assignment of lease payments		1,680,736				6,853				4,669				—			1,692,258
	Commercial real estate
	Healthcare		338,622				4,362				—				—			342,984
	Industrial		314,225				8,817				14,991				—			338,033
	Multifamily		412,824				920				6,654				—			420,398
	Retail		423,842				2,740				11,594				—			438,176
	Office		229,947				8,524				7,822				—			246,293
	Other		708,447				22,013				28,523				—			758,983
	Construction real estate		246,204				527				337				—			247,068
	Total		$	7,390,916			$	233,740			$	104,743			$	—		$	7,729,399
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 and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
			Performing				Non-performing				Total
	31-Mar-15
	Residential real estate		$	487,742			$	17,816			$	505,558
	Indirect vehicle		271,631				1,474				273,105
	Home equity		225,407				15,671				241,078
	Other consumer		77,625				20				77,645
	Total		$	1,062,405			$	34,981			$	1,097,386
	31-Dec-14
	Residential real estate		$	485,976			$	17,311			$	503,287
	Indirect vehicle		267,297				1,543				268,840
	Home equity		236,739				15,170				251,909
	Other consumer		78,132				5				78,137
	Total		$	1,068,144			$	34,029			$	1,102,173
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 and covered loans, as of March 31, 2015 and December 31, 2014 (in thousands):
			31-Mar-15
																		Three Months Ended
			Unpaid				Recorded				Partial				Allowance for			Average			Interest
			Principal				Investment				Charge-offs				Loan Losses			Recorded			Income
			Balance												Allocated			Investment			Recognized
	With no related allowance recorded:
	Commercial		$	9,686			$	8,925			$	761			$	—		$	10,640		$	—
	Commercial collateralized by assignment of lease payments		1,508				1,508				—				—			1,626			29
	Commercial real estate:
	Healthcare		—				—				—				—			—			—
	Industrial		5,846				4,670				1,176				—			4,962			—
	Multifamily		1,698				1,698				—				—			1,792			7
	Retail		2,019				807				1,212				—			825			—
	Office		1,608				1,031				577				—			1,609			—
	Other		1,490				1,465				25				—			1,527			—
	Residential real estate		970				970				—				—			—			—
	Construction real estate		—				—				—				—			—			—
	Indirect vehicle		—				—				—				—
	Home equity		1,025				1,025				—				—			—			—
	Other consumer		—				—				—				—			—			—
	With an allowance recorded:
	Commercial		6,464				6,464				—				2,051			6,760			—
	Commercial collateralized by assignment of lease payments		2,145				2,145				—				1,534			1,331			14
	Commercial real estate:
	Healthcare		—				—				—				—			—			—
	Industrial		146				146				—				37			49			—
	Multifamily		5,723				4,749				974				664			5,926			8
	Retail		8,889				7,493				1,396				626			7,710			—
	Office		2,369				1,866				503				484			2,274			—
	Other		12,247				12,227				20				100			13,207			—
	Residential real estate		14,153				14,153				—				3,045			14,407			—
	Construction real estate		2,708				337				2,371				162			431			—
	Indirect vehicle		164				164				—				14			372			—
	Home equity		26,954				26,954				—				2,348			27,213			—
	Other consumer		—				—				—				—			—			—
	Total		$	107,812			$	98,797			$	9,015			$	11,065		$	102,661		$	58
			31-Dec-14
			Unpaid				Recorded				Partial				Allowance for			Average			Interest
			Principal				Investment				Charge-offs				Loan Losses			Recorded			Income
			Balance												Allocated			Investment			Recognized
	With no related allowance recorded:
	Commercial		$	9,752			$	8,992			$	760			$	—		$	10,324		$	—
	Commercial collateralized by assignment of lease payments		2,316				2,316				—				—			2,569			121
	Commercial real estate:
	Healthcare		—				—				—				—			—			—
	Industrial		9,115				5,858				3,257				—			7,870			—
	Multifamily		1,733				1,733				—				—			1,928			52
	Retail		2,025				813				1,212				—			3,465			—
	Office		—				—				—				—			1,127			—
	Other		1,479				1,465				14				—			5,249			—
	Residential real estate		1,941				1,941				—				—			2,740			—
	Construction real estate		—				—				—				—			34			—
	Indirect vehicle		—				—				—				—			—			—
	Home equity		577				577				—				—			762			—
	Other consumer		—				—				—				—			—			—
	With an allowance recorded:
	Commercial		7,987				7,987				—				2,395			14,227			—
	Commercial collateralized by assignment of lease payments		715				715				—				105			1,515			91
	Commercial real estate:
	Healthcare		—				—				—				—			—			—
	Industrial		517				513				4				130			4,982			—
	Multifamily		5,680				4,709				971				996			6,354			131
	Retail		9,264				7,897				1,367				720			8,547			—
Office		4,528				2,986				1,542				545			2,833			—
Other		12,612				12,527				85				136			11,022			12
Residential real estate		14,234				14,234				—				3,126			14,632			—
Construction real estate		2,707				337				2,370				162			455			—
Indirect vehicle		227				227				—				14			358			—
Home equity		25,927				25,705				222				2,153			25,672			—
Other consumer		—				—				—				—			—			—
Total		$	113,336			$	101,532			$	11,804			$	10,482		$	126,665		$	407
Schedule of loans that have been restructured classified as performing and non-performing	The following table presents loans that were restructured during the three months ended March 31, 2015 (dollars in thousands):
			31-Mar-15
			Number of		Pre-Modification Recorded				Post-Modification Recorded				Charge-offs and
			Loans		Investment				Investment				Specific Reserves
	Performing:
	Home equity		6		$	2,346			$	2,346			$	—
	Total		6		$	2,346			$	2,346			$	—
	Non-Performing:
	Indirect vehicle		3		$	9			$	9			$	—
	Home equity		5		798				798				122
	Total		8		$	807			$	807			$	122
	The following table presents loans that were restructured during the three months ended March 31, 2014 (dollars in thousands):
			31-Mar-14
			Number of			Pre-Modification Recorded				Post-Modification Recorded				Charge-offs and
			Loans			Investment				Investment				Specific Reserves
	Performing:
	Indirect vehicle		1			$	5			$	5			$	—
	Home equity		3			1,039				1,039				—
	Total		4			$	1,044			$	1,044			$	—
	Non-Performing:
	Residential real estate		4			$	1,439			$	1,439			$	—
	Indirect vehicle		18			108				108				—
	Home equity		4			532				532				—
	Total		26			$	2,079			$	2,079			$	—
Troubled debt restructuring activity rollforward	The following table presents the troubled debt restructurings activity during the three months ended March 31, 2015 (in thousands):
			Performing				Non-performing
	Beginning balance		$	15,603			$	25,771
	Additions		2,346				807
	Charge-offs		—				(203		)
	Principal payments, net		(111		)		(619		)
	Removals		(1,185		)		(22		)
	Transfer from/to performing		221				—
	Transfer from/to non-performing		—				(221		)
	Ending balance		$	16,874			$	25,513
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, 2015 (in thousands):
		31-Mar-15
		Extended
		Maturity,				Delay in
		Amortization				Payments or
		and Reduction				Reduction of
		of Interest Rate				Interest Rate				Total
	Indirect vehicle	$	—			$	9			$	9
	Home equity	791				2,353				3,144
	Total	$	791			$	2,362			$	3,153
Allowance activity for loan losses by portfolio segment based on impairment method	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, 2015 and 2014 (in thousands):
			Commercial				Commercial				Commercial				Residential			Construction			Indirect		Home			Other consumer		Unfunded			Total
							collateralized  by				real estate				real estate			real estate			vehicle		equity					commitments
							assignment of
							lease payments
	31-Mar-15
	Allowance for credit losses:
	Three Months Ended
	Beginning balance		$	29,571			$	9,962			$	41,826			$	6,646		$	8,918		$	1,687	$	9,456		$	1,960	$	4,031		$	114,057
	Charge-offs		569				—				2,034				579			3			874		444			424		—			4,927
	Recoveries		242				749				1,375				72			2			475		101			69		—			3,085
	Provision		3,583				(886		)		791				621			556			427		(333		)	469		(254		)	4,974
	Ending balance		$	32,827			$	9,825			$	41,958			$	6,760		$	9,473		$	1,715	$	8,780		$	2,074	$	3,777		$	117,189
	Ending allowance balance attributable to loans:
	Individually evaluated for impairment		$	2,051			$	1,534			$	1,911			$	3,045		$	162		$	14	$	2,348		$	—	$	1,333		$	12,398
	Collectively evaluated for impairment		30,320				8,291				39,435				3,715			9,305			1,701		6,432			2,074		2,444			103,717
	Acquired and accounted for under ASC 310-30 (1)		456				—				612				—			6			—		—			—		—			1,074
	Total ending allowance balance		$	32,827			$	9,825			$	41,958			$	6,760		$	9,473		$	1,715	$	8,780		$	2,074	$	3,777		$	117,189
	Loans:
	Individually evaluated for impairment		$	15,389			$	3,653			$	36,152			$	15,123		$	337		$	164	$	27,979		$	—	$	—		$	98,797
	Collectively evaluated for impairment		3,243,263				1,624,378				2,489,488				490,435			183,768			272,941		213,099			77,645		—			8,595,017
	Acquired and accounted for under ASC 310-30 (1)		84,564				—				75,008				19,265			28,801			—		75			19,801		—			227,514
	Total ending loans balance		$	3,343,216			$	1,628,031			$	2,600,648			$	524,823		$	212,906		$	273,105	$	241,153		$	97,446	$	—		$	8,921,328
	31-Mar-14
	Allowance for credit losses:
	Three Months Ended
	Beginning balance		$	23,461			$	9,159			$	51,628			$	8,872		$	6,856		$	1,662	$	8,478		$	1,630	$	1,716		$	113,462
	Charge-offs		90				—				7,156				265			56			920		619			495		—			9,601
	Recoveries		1,628				—				485				519			99			442		133			78		—			3,384
	Provision		(1,061		)		(101		)		2,583				(1,039		)	(415		)	500		405			351		(73		)	1,150
	Ending balance		$	23,938			$	9,058			$	47,540			$	8,087		$	6,484		$	1,684	$	8,397		$	1,564	$	1,643		$	108,395
	Ending allowance balance attributable to loans:
	Individually evaluated for impairment		$	6,160			$	174			$	4,151			$	3,076		$	195		$	25	$	1,395		$	—	$	665		$	15,841
	Collectively evaluated for impairment		17,312				8,884				41,707				5,011			6,229			1,659		7,002			1,564		978			90,346
	Acquired and accounted for under ASC 310-30 (1)		466				—				1,682				—			60			—		—			—		—			2,208
	Total ending allowance balance		$	23,938			$	9,058			$	47,540			$	8,087		$	6,484		$	1,684	$	8,397		$	1,564	$	1,643		$	108,395
	Loans:
	Individually evaluated for impairment		$	41,191			$	4,235			$	57,960			$	18,151		$	782		$	183	$	24,810		$	—	$	—		$	147,312
	Collectively evaluated for impairment		1,208,639				1,468,386				1,565,549				287,790			132,215			265,861		233,310			64,812		—			5,226,562
	Acquired and accounted for under ASC 310-30 (1)		30,976				—				95,506				5,121			36,752			—		110			25,976		—			194,441
	Total ending loans balance		$	1,280,806			$	1,472,621			$	1,719,015			$	311,062		$	169,749		$	266,044	$	258,230		$	90,788	$	—		$	5,568,315
	(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, 2015 and 2014 (in thousands):
			Three Months Ended
			March 31,
			2015				2014
	Balance at beginning of period		$	7,434			$	2,337
	Accretion		(1,930		)		(550		)
	Other		863				574
	Balance at end of period		$	6,367			$	2,361
Purchased loans disclosures	The carrying amount of loans acquired through a business combination by loan type are as follows (in thousands):
	31-Mar-15		Purchased				Purchased Non-Credit-Impaired				Total
			Credit-Impaired				Loans
			Loans
	Covered loans:
	Commercial related (1)		$	139			$	4			$	143
	Commercial		837				273				1,110
	Commercial real estate		19,570				13,669				33,239
	Construction real estate		—				1,269				1,269
	Other		1,134				19,794				20,928
	Total covered loans		$	21,680			$	35,009			$	56,689
	Estimated (payable) receivable amount from the FDIC under the loss-share agreement (2)		$	482			$	4,125			$	4,607
	Non-covered loans:
	Commercial related (1)		$	7,033			$	11,495			$	18,528
	Commercial loans		76,279				1,285,210				1,361,489
	Commercial loans collateralized by assignment of lease payments		—				114,829				114,829
	Commercial real estate		41,769				840,863				882,632
	Construction real estate		27,532				89,200				116,732
	Other		18,212				198,740				216,952
	Total non-covered loans		$	170,825			$	2,540,337			$	2,711,162
	(1)	Commercial related loans include commercial, commercial real estate and construction real estate for the InBank, Heritage and Benchmark FDIC-assisted transactions.
	(2)	Estimated reimbursable amounts from the FDIC under the loss-share agreement exclude $1.3 million in amounts due to the FDIC related to covered other real estate owned.

Goodwill_and_Intangibles_Table

Goodwill and Intangibles (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of core deposit and client relationship intangibles	The following table presents the changes in the carrying amount of core deposit and client relationship intangibles, gross carrying amount, accumulated amortization, and net book value as of March 31, 2015 (in thousands):
		Three Months Ended
		March 31, 2015
	Balance at beginning of period	$	38,006
	Amortization expense	(1,518		)
	Balance at end of period	$	36,488
	Gross carrying amount	$	80,371
	Accumulated amortization	(43,883		)
	Net book value	$	36,488
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
	2015	$	4,445
	2016	5,157
	2017	4,637
	2018	4,221
	2019	2,743
	Thereafter	15,285
		$	36,488

Deposits_Tables

Deposits (Tables)	3 Months Ended
	Mar. 31, 2015
Deposits [Abstract]
Schedule of composition of deposits	The composition of deposits was as follows (in thousands):
		March 31,		December 31,
		2015		2014
	Demand deposit accounts, noninterest bearing	$	4,290,499	$	4,118,256
	NOW and money market accounts	4,002,818		3,913,765
	Savings accounts	969,560		940,345
	Certificates of deposit, $250,000 or more	716,701		838,928
	Other certificates of deposit	1,039,923		1,179,648
	Total	$	11,019,501	$	10,990,942

ShortTerm_Borrowings_Tables

Short-Term Borrowings (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of short-term borrowings	Short-term borrowings were as follows as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		31-Mar-15				31-Dec-14
		Weighted Average Cost		Amount		Weighted Average Cost		Amount
	Customer repurchase agreements	0.16	%	$	240,478	0.21	%	$	219,824
	Federal Home Loan Bank advances	0.11		300,000		0.13		700,000
	Federal funds purchased	0.33		74,753		0.14		11,591
		0.16	%	$	615,231	0.15	%	$	931,415

Junior_Subordinated_Notes_Issu1

Junior Subordinated Notes Issued to Capital Trusts (Tables)	3 Months Ended
	Mar. 31, 2015
JUNIOR SUBORDINATED NOTES ISSUED TO CAPITAL TRUSTS
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, 2015 (in thousands):
			Coal City		MB Financial		MB Financial		MB Financial
			Capital Trust I		Capital Trust II		Capital Trust III		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		MB Financial		FOBB		TAYC
			Capital Trust V		Capital Trust VI		Statutory Trust III (2)		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
	-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 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 discount of $7.4 million.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of outstanding financial instruments, contractual amounts of off-balance sheet credit risk	At March 31, 2015 and December 31, 2014, the following financial instruments were outstanding, the contractual amounts of which represent off-balance sheet credit risk (in thousands):
		Contractual Amount
		March 31, 2015		December 31, 2014
	Commitments to extend credit:
	Home equity lines	$	209,466	$	221,102
	Other commitments	2,651,028		2,643,220
	Letters of credit:
	Standby	132,056		131,810
	Commercial	5,992		2,401

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015 and December 31, 2014, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands):
			Total				Quoted Prices in				Significant Other				Significant
							Active Markets for				Observable Inputs				Unobservable Inputs
							Identical Assets				(Level 2)				(Level 3)
							(Level 1)
	31-Mar-15
	Financial assets
	Securities available for sale:
	U.S Government sponsored agencies and enterprises		$	66,070			$	—			$	66,070			$	—
	States and political subdivisions		403,628				—				403,165				463
	Residential mortgage-backed securities		678,475				—				678,003				472
	Commercial mortgage-backed securities		178,458				—				178,458				—
	Corporate bonds		252,042				—				252,042				—
	Equity securities		10,751				10,751				—				—
	Loans held for sale		686,838				—				686,838				—
	Loans		20,829				—				20,829				—
	Mortgage servicing rights		219,254				—				—				219,254
	Assets held in trust for deferred compensation		18,087				18,087				—				—
	Derivative financial instruments		68,283				6,427				50,642				11,214
	Financial liabilities
	Other liabilities (1)		17,633				17,633				—				—
	Derivative financial instruments		47,162				8,235				38,927				—
	31-Dec-14
	Financial assets
	Securities available for sale:
	U.S. Government sponsored agencies and enterprises		$	65,873			$	—			$	65,873			$	—
	States and political subdivisions		410,854				—				410,391				463
	Residential mortgage-backed securities		720,563				—				720,053				510
	Commercial mortgage-backed securities		187,662				—				187,662				—
	Corporate bonds		259,203				—				259,203				—
	Equity securities		10,597				10,597				—				—
	Loans held for sale		737,209				—				737,209				—
	Mortgage servicing rights		235,402				—				—				235,402
	Assets held in trust for deferred compensation		16,829				16,829				—				—
	Derivative financial instruments		46,388				1,607				39,707				5,074
	Financial liabilities
	Other liabilities (1)		16,483				16,483				—				—
	Derivative financial instruments		40,499				7,209				33,290				—
	(1)	Liabilities associated with assets held in trust for deferred compensation
Financial assets measured at fair value on a recurring and non-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 at			Valuation	Unobservable
		March 31, 2015			Technique	Input	Range
		(in thousands)
	Impaired loans	$	61,757		Appraisal of collateral	Appraisal adjustments - sales costs	5% - 10%
	Foreclosed assets	39,889			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 at
		March 31, 2015				Valuation Technique		Unobservable Input		Range
		(in thousands)
	States and political subdivisions	$	463			Discounted cash flows		Credit assumption		45% Loss
	Residential mortgage-backed securities	472				Discounted cash flows		Constant pre-payment rates (CPR)		1% - 3%
	Mortgage servicing rights	219,254				Discounted cash flows		CPR		10.4% - 14.2%
								Discount rate		9.25 - 12.00
								Maturity (months)		299 - 356
								Delinquencies		0.25 - 5.00
								Costs to service		$ 60 - $ 160
								Costs to service - delinquent		$ 100 - $ 1,000
	Derivative financial instruments (mortgage	11,214				Sales cash flows		Expected closing ratio		65% - 95%
	interest rate lock commitments)							Expected delivery price		98.86 bps - 108.93 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, 2015 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)	31-Mar-15
	Weighted average CPR	13.6		%
	Impact on fair value of 10% adverse change	$	(9,979	)
	Impact on fair value of 20% adverse change	(19,144		)
	Weighted average discount rate	9.42		%
	Impact on fair value of 10% adverse change	$	(7,330	)
	Impact on fair value of 20% adverse change	(14,193		)
	Weighted average delinquency rate	0.98		%
	Impact on fair value of 10% adverse change	$	(1,310	)
	Impact on fair value of 20% adverse change	(1,977		)
	Weighted average costs to service	$	70
	Impact on fair value of 10% adverse change	(3,142		)
	Impact on fair value of 20% adverse change	(6,284		)
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,
			2015				2014				2015				2014			2015		2014
	(in thousands)		Investment Securities								Mortgage Servicing Rights							Derivatives
	Balance, beginning of period		$	973			$	5,856			$	235,402			$	—		$	5,074	$	—
	Purchases		—				—				85				—			—		—
	Originations		—				—				16,560				—			—		—
	Other comprehensive income		—				(179		)		—				—			—		—
	Included in earnings		—				—				(32,793		)		—			6,140		—
	Principal payments		(38		)		(178		)		—				—			—		—
	Balance, ending of period		$	935			$	5,499			$	219,254			$	—		$	11,214	$	—
Assets measured at fair value on a nonrecurring basis	Assets measured at fair value on a nonrecurring basis as of March 31, 2015 and December 31, 2014 are included in the table below (in thousands):
			Total				Quoted Prices in Active				Significant Other				Significant
							Markets for Identical				Observable Inputs				Unobservable Inputs
							Assets (Level 1)				(Level 2)				(Level 3)
	31-Mar-15
	Financial assets:
	Impaired loans		$	61,757			$	—			$	—			$	61,757
	Non-financial assets:
	Foreclosed assets		39,889				—				—				39,889
	31-Dec-14
	Financial assets:
	Impaired loans		$	61,717			$	—			$	—			$	61,717
	Non-financial assets:
	Foreclosed assets		38,619				—				—				38,619
Estimated fair values of financial instruments	The estimated fair values of financial instruments are as follows (in thousands):
			31-Mar-15
			Carrying Amount				Estimated Fair Value			Quoted Prices in Active			Significant Other			Significant
										Markets for Identical			Observable Inputs			Unobservable Inputs
										Assets (Level 1)			(Level 2)			(Level 3)
	Financial Assets:
	Cash and due from banks		$	248,840			$	248,840		$	248,840		$	—		$	—
	Interest earning deposits with banks		52,212				52,212			52,212			—			—
	Investment securities available for sale		1,589,424				1,589,424			10,751			1,577,738			935
	Investment securities held to maturity		1,000,859				1,045,205			—			1,045,205			—
	Non-marketable securities - FHLB and FRB stock		87,677				87,677			—			—			87,677
	Loans held for sale		686,838				686,838			—			686,838			—
	Loans, net		8,807,916				8,870,489			—			20,829			8,849,660
	Accrued interest receivable		46,532				46,532			46,532			—			—
	Derivative financial instruments		68,283				68,283			6,427			50,642			11,214
	Financial Liabilities:
	Noninterest bearing deposits		$	4,290,499			$	4,290,499		$	4,290,499		$	—		$	—
	Interest bearing deposits		6,729,002				6,734,854			—			—			6,734,854
	Short-term borrowings		615,231				615,216			—			—			615,216
	Long-term borrowings		85,477				88,299			—			—			88,299
	Junior subordinated notes issued to capital trusts		185,874				123,059			—			—			123,059
	Accrued interest payable		3,005				3,005			3,005			—			—
	Derivative financial instruments		47,162				47,162			8,235			38,927			—
			31-Dec-14
			Carrying Amount				Estimated Fair Value			Quoted Prices in Active			Significant Other			Significant
										Markets for Identical			Observable Inputs			Unobservable Inputs
										Assets (Level 1)			(Level 2)			(Level 3)
	Financial Assets:
	Cash and due from banks		$	256,804			$	256,804		$	256,804		$	—		$	—
	Interest earning deposits with banks		55,277				55,277			55,277			—			—
	Investment securities available for sale		1,654,752				1,654,752			10,597			1,643,182			973
	Investment securities held to maturity		993,380				1,035,061			—			1,035,061			—
	Non-marketable securities - FHLB and FRB stock		75,569				75,569			—			—			75,569
	Loans held for sale		737,209				737,209			—			737,209			—
	Loans, net		8,973,191				8,956,494			—			—			8,956,494
	Accrued interest receivable		49,065				49,065			49,065			—			—
	Derivative financial instruments		46,388				46,388			1,607			39,707			5,074
	Financial Liabilities:
	Non-interest bearing deposits		$	4,118,256			$	4,118,256		$	4,118,256		$	—		$	—
	Interest bearing deposits		6,872,686				6,877,349			—			—			6,877,349
	Short-term borrowings		931,415				931,415			—			—			931,415
	Long-term borrowings		82,916				86,025			—			—			86,025
	Junior subordinated notes issued to capital trusts		185,778				122,408			—			—			122,408
	Accrued interest payable		3,709				3,709			3,709			—			—
	Derivative financial instruments		40,499				40,499			7,209			33,290			—

Stock_Incentive_Plans_Tables

Stock Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan	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,
		2015				2014
	Total cost of share-based payment plans during the period	$	3,605			$	2,012
	Amount of related income tax benefit recognized in income	1,412				$	790
Schedule of Share-based Compensation, Stock Options, Activity	The following table summarizes stock options outstanding for the three months ended March 31, 2015:
		Number of			Weighted			Weighted	Aggregate
		Options			Average			Average	Intrinsic
					Exercise			Remaining	Value
					Price			Contractual	(in thousands)
								Term
								(In Years)
	Options outstanding as of December 31, 2014	2,250,714			$	27.94		4.39
	Granted	296,413			31.26
	Exercised	(7,284	)		19.85
	Expired or cancelled	(3,933	)		30.34
	Forfeited	(2,928	)		25
	Options outstanding as of March 31, 2015	2,532,982			$	28.35		4.81	$	11,342
	Options exercisable as of March 31, 2015	1,729,575			$	29.07		3.12	$	7,723
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following assumptions were used for options granted during the three months ended March 31, 2015:
		March 31, 2015
	Risk-free interest rate	1.71		%
	Expected volatility of Company’s stock	30.43		%
	Expected dividend yield	1.79		%
	Expected life of options	5.9 years
	Weighted average fair value per option of options granted during the year	$	8.08
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity	The following is a summary of changes in restricted shares and units for the three months ended March 31, 2015:
		Number of			Weighted
		Shares and Units			Average
					Grant Date
					Fair Value
	Shares Outstanding at December 31, 2014	801,085			$	26.99
	Granted	490,504			31.65
	Vested	(94,740	)		27.74
	Forfeited	(3,539	)		27.08
	Shares Outstanding at March 31, 2015	1,193,310			$	28.85

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015 and December 31, 2014 (in thousands):
		Asset Derivatives										Liability Derivatives
		31-Mar-15						31-Dec-14				31-Mar-15					31-Dec-14
		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)	$	—		$	—		$	—	$	—	$	187	$	(14	)	$	197		$	(15	)
	Stand-alone derivative instruments: (2)
	Interest rate swap contracts	2,072,809			50,633			1,509,930		37,039		1,268,604		(34,942		)	2,001,787			(30,761		)
	Interest rate options contracts	617,089			982			55,830		283		67,089		(260		)	55,830			(283		)
	Foreign exchange contracts	49,017			4,470			27,402		2,276		46,904		(4,181		)	27,002			(2,109		)
	Spot foreign exchange contracts	210			6			512		5		462		(46		)	304			(18		)
	Mortgage related derivatives	955,583			12,192			871,446		6,785		1,271,000		(7,719		)	879,841			(7,313		)
	Total non-hedging derivative instruments	3,694,708			68,283			2,465,120		46,388		2,654,059		(47,148		)	2,964,764			(40,484		)
	Total	$	3,694,708		$	68,283		$	2,465,120	$	46,388	$	2,654,246	$	(47,162	)	$	2,964,961		$	(40,499	)
	(1) Hedged fixed-rate commercial real estate loans
	(2) These portfolio swaps are not designated as hedging instruments under ASC Topic 815.
Schedule of the amount of gains and losses on derivative contracts designated as hedges and not designated as hedges	Amounts included in the other income in the consolidated statements of operations related to derivative financial instruments were as follows (in thousands):
		Three Months Ended
		March 31,
		2015			2014
	Derivative instruments designated as hedges of fair value:
	Interest rate swap contracts	$	1		$	—
	Stand-alone derivative instruments:
	Interest rate swap contracts	11,125			9
	Interest rate options contracts	723			—
	Foreign exchange contracts	122			61
	Spot foreign exchange contracts	(28		)	8
	Mortgage related derivatives	908			3
	Total non-hedging derivative instruments	12,850			81
	Total	$	12,851		$	81
Schedule of Derivative Instruments
		Financial Assets										Financial Liabilities
		Net Amount Recognized			Financial Instruments			Collateral		Net Amount		Net Amount Recognized		Financial Instruments			Collateral			Net Amount
	Derivatives:
	Counterparty A	$	19		$	(19	)	$	—	$	—	$	10,604	$	(19	)	$	(10,585	)	$	—
	Counterparty B	27			(27		)	—		—		4,962		(27		)	(4,935		)	—
	Counterparty C	9,792			(9,792		)	—		—		13,218		(9,792		)	(3,426		)	—
	Other counterparties	11,822			(6,917		)	—		4,905		16,195		(6,918		)	(7,745		)	1,532
	Total derivatives	21,660			(16,755		)	—		4,905		44,979		(16,756		)	(26,691		)	1,532
	Repurchase agreements	—			—			—		—		240,478		—			(240,478		)	—
	Total	$	21,660		$	(16,755	)	$	—	$	4,905	$	285,457	$	(16,756	)	$	(267,169	)	$	1,532
		Financial Assets										Financial Liabilities
		Net Amount Recognized			Financial Instruments			Collateral		Net Amount		Net Amount Recognized		Financial Instruments			Collateral			Net Amount
	Derivatives:
	Counterparty A	$	13		$	(13	)	$	—	$	—	$	9,556	$	(13	)	$	(9,543	)	$	—
	Counterparty B	145			(145		)	—		—		3,736		(145		)	(3,591		)	—
	Counterparty C	6,123			(6,123		)	—		—		10,335		(6,122		)	(4,213		)	—
	Other counterparties	7,671			(3,920		)	—		3,751		14,300		(3,920		)	(8,663		)	1,717
	Total derivatives	13,952			(10,201		)	—		3,751		37,927		(10,200		)	(26,010		)	1,717
	Repurchase agreements	—			—			—		—		219,824		—			(219,824		)	—
	Total	$	13,952		$	(10,201	)	$	—	$	3,751	$	257,751	$	(10,200	)	$	(245,834	)	$	1,717
	Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of March 31, 2015 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 swaps, caps and floors	$	17,959		$	—		$	17,959	$	34,795	$	—	$	34,795
	Foreign currency forward contracts	2,307			—			2,307		2,050		—		2,050
	Mortgage related derivatives	1,394			—			1,394		8,134		—		8,134
	Total derivatives	21,660			—			21,660		44,979		—		44,979
	Repurchase agreements	—			—			—		240,478		—		240,478
	Total	$	21,660		$	—		$	21,660	$	285,457	$	—	$	285,457
	Information about the Company's financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2014 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 swaps, caps and floors	$	10,727		$	—		$	10,727	$	29,916	$	—	$	29,916
	Foreign currency forward contracts	1,525			—			1,525		709		—		709
	Mortgage related derivatives	1,700			—			1,700		7,302		—		7,302
	Total derivatives	13,952			—			13,952		37,927		—		37,927
	Repurchase agreements	—			—			—		219,824		—		219,824
	Total	$	13,952		$	—		$	13,952	$	257,751	$	—	$	257,751

Operating_Segments_Tables

Operating Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment	The following tables present summary financial information for the reportable segments (in thousands):
		Banking		Leasing		Mortgage Banking			Consolidated
	Three months ended March 31, 2015
	Net interest income	$	104,126	$	3,015	$	6,254		$	113,395
	Provision for credit losses	4,974		—		—			4,974
	Non-interest income	31,517		25,203		24,548			81,268
	Non-interest expense (1)	95,334		13,656		30,930			139,920
	Income tax expense	9,962		5,747		(51		)	15,658
	Net income	$	25,373	$	8,815	$	(77	)	$	34,111
	Total assets	$	12,246,659	$	937,903	$	1,143,748		$	14,328,310
	Three months ended March 31, 2014
	Net interest income	$	66,324	$	1,004	$	—		$	67,328
	Provision for credit losses	1,150		—		—			1,150
	Non-interest income	23,701		12,852		59			36,612
	Non-interest expense	68,334		7,713		—			76,047
	Income tax expense	4,483		2,291		—			6,774
	Net income	$	16,058	$	3,852	$	59		$	19,969
	Total assets	$	8,968,195	$	469,108	$	—		$	9,437,303
	(1)	Includes merger related expenses of $8.1 million and $680 thousand in the banking segment for the three months ended March 31, 2015 and 2014, respectively.

Earnings_Per_Common_Share_Deta

Earnings Per Common Share (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Basic and diluted earnings per common share:
Net income	$34,111	$19,969
Less: preferred stock dividends	2,000	0
Net income available to common stockholders	32,111	19,969
Earnings allocated to common stockholders	32,110	19,969
Weighted average shares outstanding for basic earnings per common share	74,567,104	54,639,951
Weighted average shares outstanding for diluted earnings per common share	75,164,716	55,265,188
Basic earnings per common share	$0.43	$0.37
Diluted earnings per common share	$0.43	$0.36
Common Stock
Basic and diluted earnings per common share:
Distributed earnings allocated to common stock	10,610	6,666
Undistributed earnings	23,501	13,303
Net income	34,111	19,969
Net income available to common stockholders	32,111	19,969
Dilutive effect of equity awards	597,612	625,237
Weighted average shares outstanding for diluted earnings per common share	75,164,716	55,265,188
Participating Securities
Basic and diluted earnings per common share:
Less: earnings allocated to participating securities	$1	$0

Business_Combinations_Details

Business Combinations (Details) (USD $)	0 Months Ended	3 Months Ended		0 Months Ended
	Aug. 18, 2014	Mar. 31, 2015	Mar. 31, 2014	Aug. 15, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill		$711,521,000			$711,521,000
Taylor Capital Group, Inc.
Business Acquisition [Line Items]
Amount called by each right	4.08
Cash paid	129,510,000
Cash paid, net, stock options and warrants	4,400,000
Goodwill	288,152,000
Pretax merger related costs		8,100,000	680,000
Taylor Capital Group, Inc. | Restricted stock
Business Acquisition [Line Items]
Cash paid	$3,700,000
Taylor Capital Group, Inc. | Common Stock
Business Acquisition [Line Items]
Number of securities called by each right (in shares)	0.64318
Number of shares issued	19,600,000			19,602,482

Business_Combinations_Details_

Business Combinations (Details 2) (USD $)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 18, 2014	Aug. 15, 2014	Mar. 31, 2015	Dec. 31, 2014
ASSETS
Goodwill			$711,521	$711,521
LIABILITIES
Series A preferred stock at $28.82 per share at August 15, 2014			115,280	115,280
Consideration excluding Series A preferred stock:
Preferred stock, stated value per share			$0.01	$0.01
Taylor Capital Group, Inc.
ASSETS
Cash and cash equivalents	154,684
Investment securities available for sale	826,691
Investment securities held to maturity	22,599
Non-marketable securities - FRB and FHLB Stock	50,620
Loans held for sale	670,671
Loans	3,532,211
Leases investments	11,885
Premises and equipment	19,701
Goodwill	288,152
Core deposit intangible	20,079
Mortgage servicing rights	224,453
Other real estate owned	4,720
Other assets	130,478
Total assets	5,956,944
LIABILITIES
Deposits	3,953,213
Short-term borrowings	1,035,800
Junior subordinated notes issued to capital trusts	80,843
Accrued expenses and other liabilities	123,028
Total liabilities	5,192,884
Total identifiable net assets less Series A preferred stock	648,780
Consideration excluding Series A preferred stock:
Market value of common stock at $26.49 per share at August 15, 2014 (19,602,482 shares of common stock issued)	519,270
Cash paid	129,510
Total fair value of consideration, excluding Series A preferred stock	648,780
Taylor Capital Group, Inc. | Series A Preferred Stock
LIABILITIES
Series A preferred stock at $28.82 per share at August 15, 2014	$115,280
Consideration excluding Series A preferred stock:
Preferred stock, stated value per share		$28.82
Common Stock | Taylor Capital Group, Inc.
Consideration excluding Series A preferred stock:
Share price		$26.49
Number of shares issued	19,600,000	19,602,482

Business_Combinations_Details_1

Business Combinations (Details 3) (Taylor Capital Group, Inc., USD $)	Aug. 18, 2014
In Thousands, unless otherwise specified
Business Combination, Acquired Receivables [Abstract]
Fair value of acquired loans	$3,532,211
Purchased Credit Impaired Loans Receivable
Business Combination, Acquired Receivables [Abstract]
Contractually required principal and interest payments	244,650
Nonaccretable difference	-34,219
Cash flows expected to be collected	210,431
Accretable difference	-5,626
Fair value of acquired loans	204,805
Purchased Non-Credit Impaired Loans Receivable
Business Combination, Acquired Receivables [Abstract]
Fair value of acquired loans	3,327,406
Contractually required principal and interest payments	3,707,463
Contractually required interest payments not expected to be collected due to estimated prepayments	-302,329
Cash flows expected to be collected	3,405,134
Accretable difference	($77,728)

Business_Combinations_Details_2

Business Combinations (Details 4) (Taylor Capital Group, Inc., USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Taylor Capital Group, Inc.
Business Acquisition [Line Items]
Pretax merger related costs	$8,100,000	$680,000
Total revenues (net interest income plus non-interest income)		185,028,000
Net income		$34,752,000

Investment_Securities_Details

Investment Securities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available for Sale
Amortized Cost	$1,548,972	$1,624,268
Gross Unrealized Gains	43,437	35,370
Gross Unrealized Losses	-2,985	-4,886
Fair Value	1,589,424	1,654,752
Held to Maturity
Investment securities held to maturity	1,000,859	993,380
Gross Unrealized Gains	44,630	42,063
Gross Unrealized Losses	-284	-382
Investment securities held to maturity	1,045,205	1,035,061
Total Available for Sale and Held to Maturity Investment Securities
Amortized Cost	2,549,831	2,617,648
Gross Unrealized Gains	88,067	77,433
Gross Unrealized Losses	-3,269	-5,268
Fair Value	2,634,629	2,689,813
U.S. Government sponsored agencies and enterprises
Available for Sale
Amortized Cost	64,411	64,612
Gross Unrealized Gains	1,659	1,281
Gross Unrealized Losses	0	-20
Fair Value	66,070	65,873
States and political subdivisions
Available for Sale
Amortized Cost	381,704	390,076
Gross Unrealized Gains	21,953	20,846
Gross Unrealized Losses	-29	-68
Fair Value	403,628	410,854
Held to Maturity
Investment securities held to maturity	764,931	752,558
Gross Unrealized Gains	32,136	30,089
Gross Unrealized Losses	-284	-382
Investment securities held to maturity	796,783	782,265
Total Available for Sale and Held to Maturity Investment Securities
Percentage of securities consisting general obligation issues	93.00%
States and political subdivisions | State of Illinois
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	25.00%
Residential mortgage-backed securities
Available for Sale
Amortized Cost	666,904	713,413
Gross Unrealized Gains	12,383	8,977
Gross Unrealized Losses	-812	-1,827
Fair Value	678,475	720,563
Held to Maturity
Investment securities held to maturity	235,928	240,822
Gross Unrealized Gains	12,494	11,974
Gross Unrealized Losses	0	0
Investment securities held to maturity	248,422	252,796
Commercial mortgage-backed securities
Available for Sale
Amortized Cost	174,823	186,110
Gross Unrealized Gains	3,816	1,772
Gross Unrealized Losses	-181	-220
Fair Value	178,458	187,662
Corporate bonds
Available for Sale
Amortized Cost	250,543	259,526
Gross Unrealized Gains	3,462	2,428
Gross Unrealized Losses	-1,963	-2,751
Fair Value	252,042	259,203
Equity securities
Available for Sale
Amortized Cost	10,587	10,531
Gross Unrealized Gains	164	66
Gross Unrealized Losses	0	0
Fair Value	$10,751	$10,597

Investment_Securities_Details_

Investment Securities (Details 2) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified	Security_Position	Security_Position
Available for Sale
Less Than 12 Months, Fair Value	$110,192	$405,448
Less Than 12 Months, Unrealized Losses	-928	-2,756
12 Months or More, Fair Value	55,191	42,606
12 Months or More, Unrealized Losses	-2,057	-2,130
Total Fair Value	165,383	448,054
Total Unrealized Losses	-2,985	-4,886
Total
Less Than 12 Months, Fair Value	146,811	434,234
Less Than 12 Months, Unrealized Losses	-1,065	-2,886
12 Months or More, Fair Value	61,431	56,844
12 Months or More, Unrealized Losses	-2,204	-2,382
Total Fair Value	208,242	491,078
Total Unrealized Losses	-3,269	-5,268
Number of security positions in the investment portfolio in an unrealized loss position	97	168
U.S. Government sponsored agencies and enterprises
Available for Sale
Less Than 12 Months, Fair Value		9,644
Less Than 12 Months, Unrealized Losses		-20
12 Months or More, Fair Value		0
12 Months or More, Unrealized Losses		0
Total Fair Value		9,644
Total Unrealized Losses		-20
States and political subdivisions
Available for Sale
Less Than 12 Months, Fair Value	4,761	7,784
Less Than 12 Months, Unrealized Losses	-10	-21
12 Months or More, Fair Value	2,253	3,558
12 Months or More, Unrealized Losses	-19	-47
Total Fair Value	7,014	11,342
Total Unrealized Losses	-29	-68
Held to maturity
Less Than 12 Months, Fair Value	36,619	28,786
Less Than 12 Months, Unrealized Losses	-137	-130
12 Months or More, Fair Value	6,240	14,238
12 Months or More, Unrealized Losses	-147	-252
Total Fair Value	42,859	43,024
Total Unrealized Losses	-284	-382
Residential mortgage-backed securities
Available for Sale
Less Than 12 Months, Fair Value	62,437	235,818
Less Than 12 Months, Unrealized Losses	-278	-1,336
12 Months or More, Fair Value	43,263	29,373
12 Months or More, Unrealized Losses	-534	-491
Total Fair Value	105,700	265,191
Total Unrealized Losses	-812	-1,827
Commercial mortgage-backed securities
Available for Sale
Less Than 12 Months, Fair Value	16,752	89,509
Less Than 12 Months, Unrealized Losses	-181	-220
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Total Fair Value	16,752	89,509
Total Unrealized Losses	-181	-220
Corporate bonds
Available for Sale
Less Than 12 Months, Fair Value	26,242	62,693
Less Than 12 Months, Unrealized Losses	-459	-1,159
12 Months or More, Fair Value	9,675	9,675
12 Months or More, Unrealized Losses	-1,504	-1,592
Total Fair Value	35,917	72,368
Total Unrealized Losses	($1,963)	($2,751)

Investment_Securities_Details_1

Investment Securities (Details 3) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Amortized cost and fair value of investment securities by contractual maturity
Realized gains	$759,000	$318,000
Realized losses	-1,219,000	-1,000
Net (losses) gains	-460,000	317,000
Amortized Cost, Available for sale
Due in one year or less	17,722,000
Due after one year through five years	291,975,000
Due after five years through ten years	42,645,000
Due after ten years	344,316,000
Amortized Cost	1,548,972,000		1,624,268,000
Fair Value, Available for sale
Due in one year or less	17,770,000
Due after one year through five years	294,881,000
Due after five years through ten years	44,133,000
Due after ten years	364,956,000
Fair Value	1,589,424,000		1,654,752,000
Amortized Cost, Held to maturity
Due in one year or less	52,102,000
Due in after one year through five years	222,670,000
Due after five years through ten years	99,975,000
Due after ten years	390,184,000
Investment securities held to maturity	1,000,859,000		993,380,000
Fair value, Held to maturity
Due in one year or less	52,249,000
Due in after one year through five years	224,797,000
Due after five years through ten years	104,546,000
Due after ten years	415,191,000
Investment securities held to maturity	1,045,205,000		1,035,061,000
Total Available for Sale and Held to Maturity Investment Securities
Amortized Cost	2,549,831,000		2,617,648,000
Fair Value	2,634,629,000		2,689,813,000
Pledged financial instruments, not separately reported, securities	1,500,000,000		1,500,000,000
Pledged financial instruments, not separately reported, securities required to be pledged	908,600,000		980,400,000
Investment securities pledged as collateral for long-term Federal Home Loan Bank advances	200,900,000		226,900,000
Equity securities
Amortized Cost, Available for sale
Amortized Cost	10,587,000		10,531,000
Fair Value, Available for sale
Fair Value	10,751,000		10,597,000
Residential and commercial mortgage-backed securities
Amortized Cost, Available for sale
Amortized Cost	841,727,000
Fair Value, Available for sale
Fair Value	856,933,000
Residential mortgage-backed securities
Amortized Cost, Available for sale
Amortized Cost	666,904,000		713,413,000
Fair Value, Available for sale
Fair Value	678,475,000		720,563,000
Amortized Cost, Held to maturity
Investment securities held to maturity	235,928,000		240,822,000
Fair value, Held to maturity
Investment securities held to maturity	$248,422,000		$252,796,000

Loans_Details

Loans (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
	investmentrating
Loans
Total loans, excluding purchased credit impaired and covered loans	$8,693,814,000	$8,831,572,000
Purchased credit impaired and covered loans	227,514,000	251,645,000
Total loans	8,921,328,000	9,083,217,000	5,568,315,000
Number of highest rating categories by rating services company	1
Number of highest rating categories to be achieved for classification as investment grade companies	4
Percentage of collateral pledge of first mortgage loans as per agreement	133.00%
Percentage of collateral pledge of home equity loans as per agreement	250.00%
Loans pledged as collateral for long-term Federal Home Loan Bank advances	3,500,000,000	2,000,000,000
Loans required to be pledged as collateral for long-term Federal Home Loan Bank advances	1,300,000,000	1,300,000,000
Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	3,258,652,000	3,245,206,000
Total loans	3,343,216,000		1,280,806,000
Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	1,628,031,000	1,692,258,000
Total loans	1,628,031,000		1,472,621,000
Commercial real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	2,525,640,000	2,544,867,000
Total loans	2,600,648,000		1,719,015,000
Residential real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	505,558,000	503,287,000
Total loans	524,823,000		311,062,000
Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	184,105,000	247,068,000
Total loans	212,906,000		169,749,000
Indirect vehicle
Loans
Total loans, excluding purchased credit impaired and covered loans	273,105,000	268,840,000
Total loans	273,105,000		266,044,000
Home equity lines
Loans
Total loans, excluding purchased credit impaired and covered loans	241,078,000	251,909,000
Total loans	241,153,000		258,230,000
Other consumer
Loans
Total loans, excluding purchased credit impaired and covered loans	77,645,000	78,137,000
Total loans	$97,446,000		$90,788,000

Loans_Details_2

Loans (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	$8,693,814	$8,831,572
Total loans	8,921,328	9,083,217	5,568,315
Period past due of recorded investment in loans (in days)	90 days
Commercial loans
Contractual aging of the recorded investment in loans
Current	3,220,398	3,231,571
30-59 days, past due	27,393	8,222
60-89 days, past due	1,899	0
Loans past due, 90 days or more	8,962	5,413
Total, past due	38,254	13,635
Total loans, excluding covered loans	3,258,652	3,245,206
Total loans	3,343,216		1,280,806
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	13,897	14,088
Loans past due 90 days or more and still accruing	75	0
Commercial loans collateralized by assignment of lease payments
Contractual aging of the recorded investment in loans
Current	1,611,508	1,679,991
30-59 days, past due	12,350	2,025
60-89 days, past due	2,062	6,095
Loans past due, 90 days or more	2,111	4,147
Total, past due	16,523	12,267
Total loans, excluding covered loans	1,628,031	1,692,258
Total loans	1,628,031		1,472,621
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	3,602	2,404
Loans past due 90 days or more and still accruing	741	3,566
Commercial real estate
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	2,525,640	2,544,867
Total loans	2,600,648		1,719,015
Healthcare
Contractual aging of the recorded investment in loans
Current	344,393	342,984
30-59 days, past due	0	0
60-89 days, past due	0	0
Loans past due, 90 days or more	0	0
Total, past due	0	0
Total loans, excluding covered loans	344,393	342,984
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	0	0
Loans past due 90 days or more and still accruing	0	0
Industrial
Contractual aging of the recorded investment in loans
Current	334,667	333,907
30-59 days, past due	0	944
60-89 days, past due	0	0
Loans past due, 90 days or more	2,309	3,182
Total, past due	2,309	4,126
Total loans, excluding covered loans	336,976	338,033
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	4,816	6,371
Loans past due 90 days or more and still accruing	0	0
Multifamily
Contractual aging of the recorded investment in loans
Current	372,358	417,504
30-59 days, past due	2,823	1,377
60-89 days, past due	0	0
Loans past due, 90 days or more	1,336	1,517
Total, past due	4,159	2,894
Total loans, excluding covered loans	376,517	420,398
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	5,008	5,333
Loans past due 90 days or more and still accruing	0	0
Retail
Contractual aging of the recorded investment in loans
Current	436,710	432,718
30-59 days, past due	240	2,481
60-89 days, past due	1,817	652
Loans past due, 90 days or more	2,054	2,325
Total, past due	4,111	5,458
Total loans, excluding covered loans	440,821	438,176
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	2,898	2,986
Loans past due 90 days or more and still accruing	0	0
Office
Contractual aging of the recorded investment in loans
Current	243,266	244,166
30-59 days, past due	1,235	0
60-89 days, past due	23	0
Loans past due, 90 days or more	2,048	2,127
Total, past due	3,306	2,127
Total loans, excluding covered loans	246,572	246,293
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	3,268	3,644
Loans past due 90 days or more and still accruing	0	464
Other
Contractual aging of the recorded investment in loans
Current	776,851	754,031
30-59 days, past due	1,156	307
60-89 days, past due	281	2,421
Loans past due, 90 days or more	2,073	2,224
Total, past due	3,510	4,952
Total loans, excluding covered loans	780,361	758,983
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	13,655	13,541
Loans past due 90 days or more and still accruing	0	324
Residential real estate
Contractual aging of the recorded investment in loans
Current	492,557	485,492
30-59 days, past due	5,060	8,038
60-89 days, past due	951	2,319
Loans past due, 90 days or more	6,990	7,438
Total, past due	13,001	17,795
Total loans, excluding covered loans	505,558	503,287
Total loans	524,823		311,062
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	16,925	17,311
Loans past due 90 days or more and still accruing	891	0
Construction real estate
Contractual aging of the recorded investment in loans
Current	183,768	246,731
30-59 days, past due	0	0
60-89 days, past due	0	0
Loans past due, 90 days or more	337	337
Total, past due	337	337
Total loans, excluding covered loans	184,105	247,068
Total loans	212,906		169,749
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	337	337
Loans past due 90 days or more and still accruing	0	0
Indirect vehicle
Contractual aging of the recorded investment in loans
Current	270,474	265,296
30-59 days, past due	1,933	2,516
60-89 days, past due	473	702
Loans past due, 90 days or more	225	326
Total, past due	2,631	3,544
Total loans, excluding covered loans	273,105	268,840
Total loans	273,105		266,044
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	1,473	1,542
Loans past due 90 days or more and still accruing	0	0
Home equity lines
Contractual aging of the recorded investment in loans
Current	232,851	242,756
30-59 days, past due	2,551	2,717
60-89 days, past due	268	1,039
Loans past due, 90 days or more	5,408	5,397
Total, past due	8,227	9,153
Total loans, excluding covered loans	241,078	251,909
Total loans	241,153		258,230
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	15,672	15,171
Loans past due 90 days or more and still accruing	0	0
Other consumer
Contractual aging of the recorded investment in loans
Current	77,546	78,106
30-59 days, past due	76	16
60-89 days, past due	23	12
Loans past due, 90 days or more	0	3
Total, past due	99	31
Total loans, excluding covered loans	77,645	78,137
Total loans	97,446		90,788
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	20	5
Loans past due 90 days or more and still accruing	0	0
Gross loans, excluding covered loans
Contractual aging of the recorded investment in loans
Current	8,597,347	8,755,253
30-59 days, past due	54,817	28,643
60-89 days, past due	7,797	13,240
Loans past due, 90 days or more	33,853	34,436
Total, past due	96,467	76,319
Total loans, excluding covered loans	8,693,814	8,831,572
Purchased credit-impaired including covered loans
Contractual aging of the recorded investment in loans
Current	134,140	158,215
30-59 days, past due	8,291	4,432
60-89 days, past due	1,685	585
Loans past due, 90 days or more	83,398	88,413
Total, past due	93,374	93,430
Total loans	227,514	251,645
Loans
Contractual aging of the recorded investment in loans
Current	8,731,487	8,913,468
30-59 days, past due	63,108	33,075
60-89 days, past due	9,482	13,825
Loans past due, 90 days or more	117,251	122,849
Total, past due	189,841	169,749
Total loans	8,921,328	9,083,217
Recorded investment in nonaccrual loans and loans past due ninety days or more and still accruing
Non-accrual	81,571	82,733
Loans past due 90 days or more and still accruing	1,707	4,354
Non-performing
Contractual aging of the recorded investment in loans
Current	45,674	46,149
30-59 days, past due	3,018	5,764
60-89 days, past due	911	1,099
Loans past due, 90 days or more	33,675	34,075
Total, past due	37,604	40,938
Total loans	83,278	87,087
Non-performing | Residential real estate
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	17,816	17,311
Non-performing | Indirect vehicle
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	1,474	1,543
Non-performing | Home equity lines
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	15,671	15,170
Non-performing | Other consumer
Contractual aging of the recorded investment in loans
Total loans, excluding covered loans	$20	$5

Loans_Details_3

Loans (Details 3) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Loans
Total loans, excluding purchased credit impaired and covered loans	$8,693,814,000	$8,831,572,000
Loans and Leases Receivable Net of Deferred Income of Nonperforming Substandard and Doubtful Loans	46,900,000	49,100,000
Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	3,258,652,000	3,245,206,000
Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	1,628,031,000	1,692,258,000
Healthcare
Loans
Total loans, excluding purchased credit impaired and covered loans	344,393,000	342,984,000
Industrial
Loans
Total loans, excluding purchased credit impaired and covered loans	336,976,000	338,033,000
Multifamily
Loans
Total loans, excluding purchased credit impaired and covered loans	376,517,000	420,398,000
Retail
Loans
Total loans, excluding purchased credit impaired and covered loans	440,821,000	438,176,000
Office
Loans
Total loans, excluding purchased credit impaired and covered loans	246,572,000	246,293,000
Other
Loans
Total loans, excluding purchased credit impaired and covered loans	780,361,000	758,983,000
Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	184,105,000	247,068,000
Pass
Loans
Total loans, excluding purchased credit impaired and covered loans	7,231,336,000	7,390,916,000
Pass | Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	3,029,893,000	3,036,069,000
Pass | Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	1,614,968,000	1,680,736,000
Pass | Healthcare
Loans
Total loans, excluding purchased credit impaired and covered loans	340,036,000	338,622,000
Pass | Industrial
Loans
Total loans, excluding purchased credit impaired and covered loans	314,666,000	314,225,000
Pass | Multifamily
Loans
Total loans, excluding purchased credit impaired and covered loans	368,675,000	412,824,000
Pass | Retail
Loans
Total loans, excluding purchased credit impaired and covered loans	426,760,000	423,842,000
Pass | Office
Loans
Total loans, excluding purchased credit impaired and covered loans	225,451,000	229,947,000
Pass | Other
Loans
Total loans, excluding purchased credit impaired and covered loans	727,643,000	708,447,000
Pass | Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	183,244,000	246,204,000
Special Mention
Loans
Total loans, excluding purchased credit impaired and covered loans	210,470,000	233,740,000
Special Mention | Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	155,032,000	178,984,000
Special Mention | Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	935,000	6,853,000
Special Mention | Healthcare
Loans
Total loans, excluding purchased credit impaired and covered loans	4,357,000	4,362,000
Special Mention | Industrial
Loans
Total loans, excluding purchased credit impaired and covered loans	13,200,000	8,817,000
Special Mention | Multifamily
Loans
Total loans, excluding purchased credit impaired and covered loans	1,287,000	920,000
Special Mention | Retail
Loans
Total loans, excluding purchased credit impaired and covered loans	4,165,000	2,740,000
Special Mention | Office
Loans
Total loans, excluding purchased credit impaired and covered loans	13,544,000	8,524,000
Special Mention | Other
Loans
Total loans, excluding purchased credit impaired and covered loans	17,426,000	22,013,000
Special Mention | Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	524,000	527,000
Substandard
Loans
Total loans, excluding purchased credit impaired and covered loans	154,622,000	104,743,000
Substandard | Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	73,727,000	30,153,000
Substandard | Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	12,128,000	4,669,000
Substandard | Healthcare
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Substandard | Industrial
Loans
Total loans, excluding purchased credit impaired and covered loans	9,110,000	14,991,000
Substandard | Multifamily
Loans
Total loans, excluding purchased credit impaired and covered loans	6,555,000	6,654,000
Substandard | Retail
Loans
Total loans, excluding purchased credit impaired and covered loans	9,896,000	11,594,000
Substandard | Office
Loans
Total loans, excluding purchased credit impaired and covered loans	7,577,000	7,822,000
Substandard | Other
Loans
Total loans, excluding purchased credit impaired and covered loans	35,292,000	28,523,000
Substandard | Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	337,000	337,000
Doubtful
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Healthcare
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Industrial
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Multifamily
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Retail
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Office
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Other
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Doubtful | Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	0	0
Risk Rated Category
Loans
Total loans, excluding purchased credit impaired and covered loans	7,596,428,000	7,729,399,000
Risk Rated Category | Commercial loans
Loans
Total loans, excluding purchased credit impaired and covered loans	3,258,652,000	3,245,206,000
Risk Rated Category | Commercial loans collateralized by assignment of lease payments
Loans
Total loans, excluding purchased credit impaired and covered loans	1,628,031,000	1,692,258,000
Risk Rated Category | Healthcare
Loans
Total loans, excluding purchased credit impaired and covered loans	344,393,000	342,984,000
Risk Rated Category | Industrial
Loans
Total loans, excluding purchased credit impaired and covered loans	336,976,000	338,033,000
Risk Rated Category | Multifamily
Loans
Total loans, excluding purchased credit impaired and covered loans	376,517,000	420,398,000
Risk Rated Category | Retail
Loans
Total loans, excluding purchased credit impaired and covered loans	440,821,000	438,176,000
Risk Rated Category | Office
Loans
Total loans, excluding purchased credit impaired and covered loans	246,572,000	246,293,000
Risk Rated Category | Other
Loans
Total loans, excluding purchased credit impaired and covered loans	780,361,000	758,983,000
Risk Rated Category | Construction real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	$184,105,000	$247,068,000

Loans_Details_4

Loans (Details 4) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Loans
Total loans, excluding purchased credit impaired and covered loans	$8,693,814	$8,831,572
Residential real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	505,558	503,287
Indirect vehicle
Loans
Total loans, excluding purchased credit impaired and covered loans	273,105	268,840
Home equity lines
Loans
Total loans, excluding purchased credit impaired and covered loans	241,078	251,909
Other consumer
Loans
Total loans, excluding purchased credit impaired and covered loans	77,645	78,137
Other loans
Loans
Total loans, excluding purchased credit impaired and covered loans	1,097,386	1,102,173
Performing | Residential real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	487,742	485,976
Performing | Indirect vehicle
Loans
Total loans, excluding purchased credit impaired and covered loans	271,631	267,297
Performing | Home equity lines
Loans
Total loans, excluding purchased credit impaired and covered loans	225,407	236,739
Performing | Other consumer
Loans
Total loans, excluding purchased credit impaired and covered loans	77,625	78,132
Performing | Other loans
Loans
Total loans, excluding purchased credit impaired and covered loans	1,062,405	1,068,144
Non-performing | Residential real estate
Loans
Total loans, excluding purchased credit impaired and covered loans	17,816	17,311
Non-performing | Indirect vehicle
Loans
Total loans, excluding purchased credit impaired and covered loans	1,474	1,543
Non-performing | Home equity lines
Loans
Total loans, excluding purchased credit impaired and covered loans	15,671	15,170
Non-performing | Other consumer
Loans
Total loans, excluding purchased credit impaired and covered loans	20	5
Non-performing | Other loans
Loans
Total loans, excluding purchased credit impaired and covered loans	$34,981	$34,029

Loans_Details_5

Loans (Details 5) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
	loan	loan
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	$107,812,000	$113,336,000
Recorded Investment	98,797,000	101,532,000
Partial Charge-Offs	9,015,000	11,804,000
Allowance for Loan Losses Allocated	11,065,000	10,482,000
Impaired Financing Receivable, Average Recorded Investment	102,661,000	126,665,000
Interest Income Recognized	58,000	407,000
Restructured loans	3,153,000
Financing Receivable Modifications Minimum Period of Sustained Repayment Required to Return Note to Accrual Status	6 months
Financing Receivable Modifications Restructured Loans Representing A And B Structures	1,000,000	1,000,000
Financing Receivable Modifications Restructured Loans Number of A and B Structures	1	1
Indirect vehicle
Loans individually evaluated for impairment by class of loans
Restructured loans	9,000
Home equity lines
Loans individually evaluated for impairment by class of loans
Restructured loans	3,144,000
Impaired Financing Receivable With No Allowance | Commercial loans
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	9,686,000	9,752,000
Recorded Investment	8,925,000	8,992,000
Partial Charge-Offs	761,000	760,000
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	10,640,000	10,324,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Commercial loans collateralized by assignment of lease payments
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	1,508,000	2,316,000
Recorded Investment	1,508,000	2,316,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	1,626,000	2,569,000
Interest Income Recognized	29,000	121,000
Impaired Financing Receivable With No Allowance | Healthcare
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Industrial
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	5,846,000	9,115,000
Recorded Investment	4,670,000	5,858,000
Partial Charge-Offs	1,176,000	3,257,000
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	4,962,000	7,870,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Multifamily
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	1,698,000	1,733,000
Recorded Investment	1,698,000	1,733,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	1,792,000	1,928,000
Interest Income Recognized	7,000	52,000
Impaired Financing Receivable With No Allowance | Retail
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	2,019,000	2,025,000
Recorded Investment	807,000	813,000
Partial Charge-Offs	1,212,000	1,212,000
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	825,000	3,465,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Office
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	1,608,000	0
Recorded Investment	1,031,000	0
Partial Charge-Offs	577,000	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	1,609,000	1,127,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Other
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	1,490,000	1,479,000
Recorded Investment	1,465,000	1,465,000
Partial Charge-Offs	25,000	14,000
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	1,527,000	5,249,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Residential real estate
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	970,000	1,941,000
Recorded Investment	970,000	1,941,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	2,740,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Construction real estate
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	34,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Indirect vehicle
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment		0
Interest Income Recognized		0
Impaired Financing Receivable With No Allowance | Home equity lines
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	1,025,000	577,000
Recorded Investment	1,025,000	577,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	762,000
Interest Income Recognized	0	0
Impaired Financing Receivable With No Allowance | Other consumer
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Commercial loans
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	6,464,000	7,987,000
Recorded Investment	6,464,000	7,987,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	2,051,000	2,395,000
Impaired Financing Receivable, Average Recorded Investment	6,760,000	14,227,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Commercial loans collateralized by assignment of lease payments
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	2,145,000	715,000
Recorded Investment	2,145,000	715,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	1,534,000	105,000
Impaired Financing Receivable, Average Recorded Investment	1,331,000	1,515,000
Interest Income Recognized	14,000	91,000
Impaired Financing Receivable With Allowance | Healthcare
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	0
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Industrial
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	146,000	517,000
Recorded Investment	146,000	513,000
Partial Charge-Offs	0	4,000
Allowance for Loan Losses Allocated	37,000	130,000
Impaired Financing Receivable, Average Recorded Investment	49,000	4,982,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Multifamily
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	5,723,000	5,680,000
Recorded Investment	4,749,000	4,709,000
Partial Charge-Offs	974,000	971,000
Allowance for Loan Losses Allocated	664,000	996,000
Impaired Financing Receivable, Average Recorded Investment	5,926,000	6,354,000
Interest Income Recognized	8,000	131,000
Impaired Financing Receivable With Allowance | Retail
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	8,889,000	9,264,000
Recorded Investment	7,493,000	7,897,000
Partial Charge-Offs	1,396,000	1,367,000
Allowance for Loan Losses Allocated	626,000	720,000
Impaired Financing Receivable, Average Recorded Investment	7,710,000	8,547,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Office
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	2,369,000	4,528,000
Recorded Investment	1,866,000	2,986,000
Partial Charge-Offs	503,000	1,542,000
Allowance for Loan Losses Allocated	484,000	545,000
Impaired Financing Receivable, Average Recorded Investment	2,274,000	2,833,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Other
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	12,247,000	12,612,000
Recorded Investment	12,227,000	12,527,000
Partial Charge-Offs	20,000	85,000
Allowance for Loan Losses Allocated	100,000	136,000
Impaired Financing Receivable, Average Recorded Investment	13,207,000	11,022,000
Interest Income Recognized	0	12,000
Impaired Financing Receivable With Allowance | Residential real estate
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	14,153,000	14,234,000
Recorded Investment	14,153,000	14,234,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	3,045,000	3,126,000
Impaired Financing Receivable, Average Recorded Investment	14,407,000	14,632,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Construction real estate
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	2,708,000	2,707,000
Recorded Investment	337,000	337,000
Partial Charge-Offs	2,371,000	2,370,000
Allowance for Loan Losses Allocated	162,000	162,000
Impaired Financing Receivable, Average Recorded Investment	431,000	455,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Indirect vehicle
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	164,000	227,000
Recorded Investment	164,000	227,000
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	14,000	14,000
Impaired Financing Receivable, Average Recorded Investment	372,000	358,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Home equity lines
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	26,954,000	25,927,000
Recorded Investment	26,954,000	25,705,000
Partial Charge-Offs	0	222,000
Allowance for Loan Losses Allocated	2,348,000	2,153,000
Impaired Financing Receivable, Average Recorded Investment	27,213,000	25,672,000
Interest Income Recognized	0	0
Impaired Financing Receivable With Allowance | Other consumer
Loans individually evaluated for impairment by class of loans
Unpaid Principal Balance	0	0
Recorded Investment	0	0
Partial Charge-Offs	0	0
Allowance for Loan Losses Allocated	0	0
Impaired Financing Receivable, Average Recorded Investment	0	0
Interest Income Recognized	0	0
Performing
Loans individually evaluated for impairment by class of loans
Restructured loans	16,900,000	15,600,000
Non-performing
Loans individually evaluated for impairment by class of loans
Restructured loans	$25,500,000	$25,800,000

Loans_Details_6

Loans (Details 6) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	note
Restructured loans
Loans required to be pledged as collateral for long-term Federal Home Loan Bank advances	$1,300,000,000		$1,300,000,000
Financing Receivable Modifications Number of Separate Notes into which Note is Restructured	2
Redefaulted loans	223,651
Period past due of recorded redefaulted loans (in days)	90 days	90 days
Performing
Restructured loans
Number of loans	6	4
Pre-Modification Recorded Investment	2,346,000	1,044,000
Post-Modification Recorded Investment	2,346,000	1,044,000
Charge-offs and Specific Reserves	0	0
Non-performing
Restructured loans
Number of loans	8	26
Pre-Modification Recorded Investment	807,000	2,079,000
Post-Modification Recorded Investment	807,000	2,079,000
Charge-offs and Specific Reserves	122,000	0
Residential real estate | Non-performing
Restructured loans
Number of loans		4
Pre-Modification Recorded Investment		1,439,000
Post-Modification Recorded Investment		1,439,000
Charge-offs and Specific Reserves		0
Indirect vehicle | Performing
Restructured loans
Number of loans		1
Pre-Modification Recorded Investment		5,000
Post-Modification Recorded Investment		5,000
Charge-offs and Specific Reserves		0
Indirect vehicle | Non-performing
Restructured loans
Number of loans	3	18
Pre-Modification Recorded Investment	9,000	108,000
Post-Modification Recorded Investment	9,000	108,000
Charge-offs and Specific Reserves	0	0
Home equity lines | Performing
Restructured loans
Number of loans	6	3
Pre-Modification Recorded Investment	2,346,000	1,039,000
Post-Modification Recorded Investment	2,346,000	1,039,000
Charge-offs and Specific Reserves	0	0
Home equity lines | Non-performing
Restructured loans
Number of loans	5	4
Pre-Modification Recorded Investment	798,000	532,000
Post-Modification Recorded Investment	798,000	532,000
Charge-offs and Specific Reserves	$122,000	0

Loans_Details_7

Loans (Details 7) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Financing Receivable, Modifications, Post Modification Recorded Investment [Roll Forward]
Transfer from/to performing	$221
Ending balance	3,153
Non-performing
Financing Receivable, Modifications, Post Modification Recorded Investment [Roll Forward]
Beginning balance	25,771
Additions	807
Charge-offs	-203
Principal payments, net	-619
Removals	-22
Transfer from/to performing	0
Transfer from/to non-performing	-221
Ending balance	25,513
Performing
Financing Receivable, Modifications, Post Modification Recorded Investment [Roll Forward]
Beginning balance	15,603
Additions	2,346
Charge-offs	0
Principal payments, net	-111
Removals	-1,185
Transfer from/to non-performing	0
Ending balance	$16,874

Loans_Details_8

Loans (Details 8) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
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
Extended Maturity and Amortization and Reduction of Interest Rate	$791
Delay in Payments or Reduction of Interest Rate	2,362
Total	3,153
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
Extended Maturity and Amortization and Reduction of Interest Rate	0
Delay in Payments or Reduction of Interest Rate	9
Total	9
Home equity lines
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
Extended Maturity and Amortization and Reduction of Interest Rate	791
Delay in Payments or Reduction of Interest Rate	2,353
Total	$3,144

Loans_Details_9

Loans (Details 9) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Allowance for credit losses [Roll Forward]
Beginning Balance	$110,026,000
Ending Balance	113,412,000
Ending allowance balance attributable to loans:
Acquired and accounted for under ASC 310-30	1,074,000	[1]	2,208,000	[1]
Unfunded Commitments
Allowance for unfunded credit commitments, beginning balance	4,031,000		1,716,000
Allowance for unfunded commitments, Provision	-254,000		-73,000
Individually evaluated for impairment for unfunded commitments	1,333,000		665,000
Unfunded commitments collectively evaluated for impairment	2,444,000		978,000
Allowance for unfunded credit commitments, ending balance	3,777,000		1,643,000
Allowance for credit losses
Allowance for credit losses, beginning balance	114,057,000		113,462,000
Allowance for loan losses and unfunded commitments charge offs	4,927,000		9,601,000
Allowance for loan losses and unfunded commitments recoveries	3,085,000		3,384,000
Allowance for loan losses and unfunded commitments provision	4,974,000		1,150,000
Allowance for credit losses, individually evaluated for impairment	12,398,000		15,841,000
Allowance for credit losses, collectively evaluated for impairment	103,717,000		90,346,000
Acquired and accounted for under ASC 310-30	1,074,000	[1]	2,208,000	[1]
Allowance for credit losses, ending balance	117,189,000		108,395,000
Loans:
Individually evaluated for impairment	98,797,000		147,312,000
Collectively evaluated for impairment	8,595,017,000		5,226,562,000
Acquired and accounted for under ASC 310-30	227,514,000	[1]	194,441,000	[1]
Total loans	8,921,328,000		5,568,315,000		9,083,217,000
Commercial loans
Allowance for credit losses [Roll Forward]
Beginning Balance	29,571,000		23,461,000
Charge-offs	569,000		90,000
Recoveries	242,000		1,628,000
Provision	3,583,000		-1,061,000
Ending Balance	32,827,000		23,938,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	2,051,000		6,160,000
Collectively evaluated for impairment	30,320,000		17,312,000
Acquired and accounted for under ASC 310-30	456,000	[1]	466,000
Allowance for credit losses
Acquired and accounted for under ASC 310-30	456,000	[1]	466,000
Loans:
Individually evaluated for impairment	15,389,000		41,191,000
Collectively evaluated for impairment	3,243,263,000		1,208,639,000
Acquired and accounted for under ASC 310-30	84,564,000	[1]	30,976,000	[1]
Total loans	3,343,216,000		1,280,806,000
Commercial loans collateralized by assignment of lease payments
Allowance for credit losses [Roll Forward]
Beginning Balance	9,962,000		9,159,000
Charge-offs	0
Recoveries	749,000
Provision	-886,000		-101,000
Ending Balance	9,825,000		9,058,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,534,000		174,000
Collectively evaluated for impairment	8,291,000		8,884,000
Loans:
Individually evaluated for impairment	3,653,000		4,235,000
Collectively evaluated for impairment	1,624,378,000		1,468,386,000
Total loans	1,628,031,000		1,472,621,000
Commercial real estate
Allowance for credit losses [Roll Forward]
Beginning Balance	41,826,000		51,628,000
Charge-offs	2,034,000		7,156,000
Recoveries	1,375,000		485,000
Provision	791,000		2,583,000
Ending Balance	41,958,000		47,540,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,911,000		4,151,000
Collectively evaluated for impairment	39,435,000		41,707,000
Acquired and accounted for under ASC 310-30	612,000	[1]	1,682,000	[1]
Allowance for credit losses
Acquired and accounted for under ASC 310-30	612,000	[1]	1,682,000	[1]
Loans:
Individually evaluated for impairment	36,152,000		57,960,000
Collectively evaluated for impairment	2,489,488,000		1,565,549,000
Acquired and accounted for under ASC 310-30	75,008,000	[1]	95,506,000	[1]
Total loans	2,600,648,000		1,719,015,000
Allowance for loan losses and unfunded commitments acquired with deteriorated credit quality	1,100,000				1,300,000
Residential real estate
Allowance for credit losses [Roll Forward]
Beginning Balance	6,646,000		8,872,000
Charge-offs	579,000		265,000
Recoveries	72,000		519,000
Provision	621,000		-1,039,000
Ending Balance	6,760,000		8,087,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	3,045,000		3,076,000
Collectively evaluated for impairment	3,715,000		5,011,000
Acquired and accounted for under ASC 310-30			0	[1]
Allowance for credit losses
Acquired and accounted for under ASC 310-30			0	[1]
Loans:
Individually evaluated for impairment	15,123,000		18,151,000
Collectively evaluated for impairment	490,435,000		287,790,000
Acquired and accounted for under ASC 310-30	19,265,000	[1]	5,121,000	[1]
Total loans	524,823,000		311,062,000
Construction real estate
Allowance for credit losses [Roll Forward]
Beginning Balance	8,918,000		6,856,000
Charge-offs	3,000		56,000
Recoveries	2,000		99,000
Provision	556,000		-415,000
Ending Balance	9,473,000		6,484,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	162,000		195,000
Collectively evaluated for impairment	9,305,000		6,229,000
Acquired and accounted for under ASC 310-30	6,000	[1]	60,000	[1]
Allowance for credit losses
Acquired and accounted for under ASC 310-30	6,000	[1]	60,000	[1]
Loans:
Individually evaluated for impairment	337,000		782,000
Collectively evaluated for impairment	183,768,000		132,215,000
Acquired and accounted for under ASC 310-30	28,801,000	[1]	36,752,000	[1]
Total loans	212,906,000		169,749,000
Indirect vehicle
Allowance for credit losses [Roll Forward]
Beginning Balance	1,687,000		1,662,000
Charge-offs	874,000		920,000
Recoveries	475,000		442,000
Provision	427,000		500,000
Ending Balance	1,715,000		1,684,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	14,000		25,000
Collectively evaluated for impairment	1,701,000		1,659,000
Loans:
Individually evaluated for impairment	164,000		183,000
Collectively evaluated for impairment	272,941,000		265,861,000
Total loans	273,105,000		266,044,000
Home equity lines
Allowance for credit losses [Roll Forward]
Beginning Balance	9,456,000		8,478,000
Charge-offs	444,000		619,000
Recoveries	101,000		133,000
Provision	-333,000		405,000
Ending Balance	8,780,000		8,397,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment	2,348,000		1,395,000
Collectively evaluated for impairment	6,432,000		7,002,000
Loans:
Individually evaluated for impairment	27,979,000		24,810,000
Collectively evaluated for impairment	213,099,000		233,310,000
Acquired and accounted for under ASC 310-30	75,000	[1]	110,000	[1]
Total loans	241,153,000		258,230,000
Other consumer
Allowance for credit losses [Roll Forward]
Beginning Balance	1,960,000		1,630,000
Charge-offs	424,000		495,000
Recoveries	69,000		78,000
Provision	469,000		351,000
Ending Balance	2,074,000		1,564,000
Ending allowance balance attributable to loans:
Individually evaluated for impairment			0
Collectively evaluated for impairment	2,074,000		1,564,000
Loans:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	77,645,000		64,812,000
Acquired and accounted for under ASC 310-30	19,801,000	[1]	25,976,000	[1]
Total loans	97,446,000		90,788,000
Purchased loans
Allowance for credit losses [Roll Forward]
Provision	-429,000
Loans:
Total loans	71,700,000
Provision and charge-offs related to the number of pools	16
Allowance for loan losses and unfunded commitments write offs net of recoveries	($220,000)
[1]	Loans acquired in business combinations and accounted for under ASC Subtopic 310-30 “Receivables — Loans and Debt Securities Acquired with Deteriorated Credit Quality.”

Loans_Details_10

Loans (Details 10) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Changes in the accretable yield for purchased credit-impaired loans
Balance at beginning of period	$7,434	$2,337
Accretion	-1,930	-550
Other	863	574
Balance at end of period	$6,367	$2,361

Loans_Details_11

Loans (Details 11) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	$56,689,000
Estimated receivable amount from the FDIC under the loss-share agreement	4,607,000	[1]
Non covered loans	2,711,162,000
Outstanding balances on purchased loans from the FDIC	86,500,000		95,100,000
Carrying amount on loans purchased from the FDIC	81,600,000		91,400,000
Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	21,680,000
Estimated receivable amount from the FDIC under the loss-share agreement	482,000	[1]
Non covered loans	170,825,000
Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	35,009,000
Estimated receivable amount from the FDIC under the loss-share agreement	4,125,000	[1]
Non covered loans	2,540,337,000
Commercial related
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	143,000	[2]
Non covered loans	18,528,000
Commercial related | Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	139,000	[2]
Non covered loans	7,033,000
Reimbursable Amount Covered Other Real Estate Owned	1,300,000
Commercial related | Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	4,000	[2]
Non covered loans	11,495,000
Commercial loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	1,110,000
Non covered loans	1,361,489,000
Commercial loans | Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	837,000
Non covered loans	76,279,000
Commercial loans | Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	273,000
Non covered loans	1,285,210,000
Commercial loans collateralized by assignment of lease payments
Purchased credit-impaired loans and non-credit-impaired loans
Non covered loans	114,829,000
Commercial loans collateralized by assignment of lease payments | Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Non covered loans	0
Commercial loans collateralized by assignment of lease payments | Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Non covered loans	114,829,000
Commercial real estate
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	33,239,000
Non covered loans	882,632,000
Commercial real estate | Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	19,570,000
Non covered loans	41,769,000
Commercial real estate | Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	13,669,000
Non covered loans	840,863,000
Construction real estate
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	1,269,000
Non covered loans	116,732,000
Construction real estate | Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	0
Non covered loans	27,532,000
Construction real estate | Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	1,269,000
Non covered loans	89,200,000
Other
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	20,928,000
Non covered loans	216,952,000
Other | Purchased Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	1,134,000
Non covered loans	18,212,000
Other | Purchased Non-Impaired Loans
Purchased credit-impaired loans and non-credit-impaired loans
Covered Loans	19,794,000
Non covered loans	198,740,000
Heritage | Commercial loans, commercial real estate receivable and construction loans
Purchased credit-impaired loans and non-credit-impaired loans
Loans not covered under the loss share agreement	3,000,000	[2]
Benchmark | Commercial loans, commercial real estate receivable and construction loans
Purchased credit-impaired loans and non-credit-impaired loans
Loans not covered under the loss share agreement	$2,800,000	[2]
[1]	Estimated reimbursable amounts from the FDIC under the loss-share agreement exclude $1.3 million in amounts due to the FDIC related to covered other real estate owned.
[2]	Commercial related loans include commercial, commercial real estate and construction real estate for the InBank, Heritage and Benchmark FDIC-assisted transactions.

Goodwill_and_Intangibles_Detai

Goodwill and Intangibles (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	segment
Goodwill and Intangible Assets Disclosure [Abstract]
Number of operating segments	3
Goodwill, Impairment Loss	$0	$0
Goodwill	$711,521,000		$711,521,000
Weighted average amortization period (in years)	5 years

Goodwill_and_Intangibles_Detai1

Goodwill and Intangibles (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Changes in the carrying amount of core deposit and client relationship intangibles
Balance at beginning of period	$38,006
Amortization expense	-1,518	-1,240
Balance at end of period	36,488
Gross carrying amount	80,371
Accumulated amortization	-43,883
Net book value	$36,488

Goodwill_and_Intangibles_Detai2

Goodwill and Intangibles (Details 3) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]
2015	$4,445
2016	5,157
2017	4,637
2018	4,221
2019	2,743
Thereafter	15,285
Total estimated future amortization expense	$36,488

Deposits_Details

Deposits (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Deposits [Abstract]
Demand deposit accounts, noninterest bearing	$4,290,499,000	$4,118,256,000
NOW and money market accounts	4,002,818,000	3,913,765,000
Savings accounts	969,560,000	940,345,000
Certificates of deposit, $250,000 or more	716,701,000	838,928,000
Other certificates of deposit	1,039,923,000	1,179,648,000
Total deposits	11,019,501,000	10,990,942,000
Brokered deposits	$395,300,000	$485,300,000

ShortTerm_Borrowings_Details

Short-Term Borrowings (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Short-term borrowings
Weighted Average Cost	0.16%	0.15%
Amount	$615,231	$931,415
Customer repurchase agreements
Short-term borrowings
Weighted Average Cost	0.16%	0.21%
Amount	240,478	219,824
Federal Home Loan Bank advances
Short-term borrowings
Weighted Average Cost	0.11%	0.13%
Amount	300,000	700,000
Federal funds purchased
Short-term borrowings
Weighted Average Cost	0.33%	0.14%
Amount	$74,753	$11,591

ShortTerm_Borrowings_Additiona

Short-Term Borrowings - Additional Information (Details) (USD $)	0 Months Ended
	Mar. 09, 2012	Mar. 31, 2015	Dec. 31, 2014
Short-term borrowings
Fixed interest rate Federal Home Loan Bank advances		$300,000,000	$700,000,000
Effective Interest Rate of Amounts Due within One Year		0.11%
Line of credit
Short-term borrowings
Unsecured line of credit	$35,000,000
Description of interest rate basis	one month LIBOR
LIBOR | Line of credit
Short-term borrowings
Debt instrument, basis spread on variable rate	1.85%

Longterm_Borrowings_Details

Long-term Borrowings (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Long-term borrowings
Federal Home Loan Bank advances	$4,100,000	$4,200,000
Effective interest rates on Federal Home Loan Bank advances, low end of range (as a percent)	3.23%
Effective interest rates on Federal Home Loan Bank advances, high end of range (as a percent)	5.87%
Long-term Debt	85,477,000	82,916,000
Notes payable to banks
Long-term borrowings
Long-term Debt	41,200,000	38,500,000
Minimum interest rates (as a percent)	2.25%
Maximum interest rates (as a percent)	12.00%
Equipment pledged as collateral	50,800,000	48,800,000
Structured repurchase agreement
Long-term borrowings
Long-term Debt	$40,000,000	$40,000,000
Term of structured repurchase agreement (in years)	10 years	10 years
Fixed interest rate, if option not exercised (as a percent)	4.75%	4.75%

Junior_Subordinated_Notes_Issu2

Junior Subordinated Notes Issued to Capital Trusts (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Outstanding junior subordinated notes
Principal balance	185,874,000		$185,778,000
Junior Subordinated Notes | Maximum
Outstanding junior subordinated notes
Period for deferment of payment of interest on notes (in years)	5 years
Coal City Capital Trust I | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	25,774,000
Debt instrument, basis spread on variable rate	1.80%
Description of annual interest rate basis	3-mo LIBOR
MB Financial Capital Trust II | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	36,083,000
Debt instrument, basis spread on variable rate	1.40%
Description of annual interest rate basis	3-mo LIBOR
MB Financial Capital Trust III | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	10,310,000
Debt instrument, basis spread on variable rate	1.50%
Description of annual interest rate basis	3-mo LIBOR
MB Financial Capital Trust IV | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	20,619,000
Debt instrument, basis spread on variable rate	1.52%
Description of annual interest rate basis	3-mo LIBOR
MB Financial Capital Trust V | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	30,928,000
Debt instrument, basis spread on variable rate	1.30%
Description of annual interest rate basis	3-mo LIBOR
MB Financial Capital Trust VI | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	23,196,000
Debt instrument, basis spread on variable rate	1.30%
Description of annual interest rate basis	3-mo LIBOR
FOBB Statutory Trust III | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	5,155,000	[1]
Debt instrument, basis spread on variable rate	2.80%	[1]
Description of annual interest rate basis	3-mo LIBOR	[1]
TAYC Capital Trust II
Outstanding junior subordinated notes
Debt Instrument, Purchase Accounting Adjustments Discount	7,400,000
TAYC Capital Trust II | Junior Subordinated Notes
Outstanding junior subordinated notes
Principal balance	41,238,000	[2]
Debt instrument, basis spread on variable rate	2.68%	[2]
Description of annual interest rate basis	3-mo LIBOR	[2]
Trust Preferred Securities | Coal City Capital Trust I
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	1.80%
Description of annual interest rate basis	3-mo LIBOR
Investment Owned, Balance, Principal Amount	25,000,000
Trust Preferred Securities | MB Financial Capital Trust II
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	1.40%
Description of annual interest rate basis	3-mo LIBOR
Investment Owned, Balance, Principal Amount	35,000,000
Trust Preferred Securities | MB Financial Capital Trust III
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	1.50%
Description of annual interest rate basis	3-mo LIBOR
Investment Owned, Balance, Principal Amount	10,000,000
Trust Preferred Securities | MB Financial Capital Trust IV
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	1.52%
Description of annual interest rate basis	3-mo LIBOR
Investment Owned, Balance, Principal Amount	20,000,000
Trust Preferred Securities | MB Financial Capital Trust V
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	1.30%
Description of annual interest rate basis	3-mo LIBOR
Investment Owned, Balance, Principal Amount	30,000,000
Trust Preferred Securities | MB Financial Capital Trust VI
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	1.30%
Description of annual interest rate basis	3-mo LIBOR
Investment Owned, Balance, Principal Amount	22,500,000
Trust Preferred Securities | FOBB Statutory Trust III
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	2.80%	[1]
Description of annual interest rate basis	3-mo LIBOR	[1]
Investment Owned, Balance, Principal Amount	5,000,000	[1]
Trust Preferred Securities | TAYC Capital Trust II
Outstanding junior subordinated notes
Debt instrument, basis spread on variable rate	2.68%	[2]
Description of annual interest rate basis	3-mo LIBOR	[2]
Investment Owned, Balance, Principal Amount	40,000,000	[2]
[1]	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.
[2]	TAYC Capital Trust II was established by 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 discount of $7.4 million.

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
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	$3,800,000
Dollar amount of letters of credit outstanding	138,000,000	134,200,000
Letters of credit issued or renewed	32,200,000
Capital expenditure commitments outstanding	2,600,000
Home equity lines
Commitments and contingencies
Dollar amount of line of credit outstanding	209,466,000	221,102,000
Other commitments
Commitments and contingencies
Dollar amount of line of credit outstanding	2,651,028,000	2,643,220,000
Standby
Commitments and contingencies
Dollar amount of line of credit outstanding	132,056,000	131,810,000
Commercial
Commitments and contingencies
Dollar amount of line of credit outstanding	$5,992,000	$2,401,000

Commitments_and_Contingencies_2

Commitments and Contingencies (Details 2) (States and political subdivisions, State of Illinois)	3 Months Ended
	Mar. 31, 2015
States and political subdivisions | State of Illinois
Concentrations of credit risk
Percentage of investments issued by states and political subdivisions that were within the state of Illinois	25.00%

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	$1,589,424		$1,654,752
Loans held for sale	686,838		737,209
Total loans, excluding purchased credit impaired and covered loans	8,693,814		8,831,572
Mortgage servicing rights	219,254		235,402
Derivative financial instruments, assets	21,660		13,952
Derivative financial instrument, liabilities	44,979		37,927
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	66,070		65,873
States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	403,628		410,854
Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	678,475		720,563
Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	178,458		187,662
Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	252,042		259,203
Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	10,751		10,597
Recurring basis
Financial assets and financial liabilities measured at fair value on a recurring basis
Loans held for sale	686,838		737,209
Total loans, excluding purchased credit impaired and covered loans	20,829
Mortgage servicing rights	219,254		235,402
Assets held in trust for deferred compensation	18,087		16,829
Derivative financial instruments, assets	68,283		46,388
Other liabilities	17,633	[1]	16,483	[1]
Derivative financial instrument, liabilities	47,162		40,499
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	66,070		65,873
Recurring basis | States and political subdivisions
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	403,628		410,854
Recurring basis | Residential mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	678,475		720,563
Recurring basis | Commercial mortgage-backed securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	178,458		187,662
Recurring basis | Corporate bonds
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	252,042		259,203
Recurring basis | Equity securities
Financial assets and financial liabilities measured at fair value on a recurring basis
Investment securities available for sale	10,751		10,597
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	10,751		10,597
Loans held for sale	0		0
Assets held in trust for deferred compensation	18,087		16,829
Derivative financial instruments, assets	6,427		1,607
Other liabilities	17,633	[1]	16,483	[1]
Derivative financial instrument, liabilities	8,235		7,209
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	10,751		10,597
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	1,577,738		1,643,182
Loans held for sale	686,838		737,209
Total loans, excluding purchased credit impaired and covered loans	20,829
Derivative financial instruments, assets	50,642		39,707
Derivative financial instrument, liabilities	38,927		33,290
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	66,070		65,873
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	403,165		410,391
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	678,003		720,053
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	178,458		187,662
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	252,042		259,203
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	935		973
Loans held for sale	0		0
Mortgage servicing rights			235,402
Derivative financial instruments, assets	11,214		5,074
Derivative financial instrument, liabilities	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	463		463
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	$472		$510
[1]	Liabilities associated with assets held in trust for deferred compensation

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	$1,589,424,000	$1,654,752,000
Mortgage servicing rights	219,254,000	235,402,000
Derivative financial instruments, assets	21,660,000	13,952,000
States and political subdivisions
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	403,628,000	410,854,000
Residential mortgage-backed securities
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	678,475,000	720,563,000
Corporate bonds
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	252,042,000	259,203,000
Recurring basis
Assets measured at fair value on a nonrecurring basis
Mortgage servicing rights	219,254,000	235,402,000
Derivative financial instruments, assets	68,283,000	46,388,000
Recurring basis | States and political subdivisions
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	403,628,000	410,854,000
Recurring basis | Residential mortgage-backed securities
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	678,475,000	720,563,000
Recurring basis | Corporate bonds
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	252,042,000	259,203,000
Significant Unobservable Inputs (Level 3) | Recurring basis
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	935,000	973,000
Mortgage servicing rights		235,402,000
Derivative financial instruments, assets	11,214,000	5,074,000
Significant Unobservable Inputs (Level 3) | Recurring basis | States and political subdivisions
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	463,000	463,000
Credit assumption (as a percent)	45.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | Residential mortgage-backed securities
Assets measured at fair value on a nonrecurring basis
Investment securities available for sale	472,000	510,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Mortgage servicing rights
Assets measured at fair value on a nonrecurring basis
Mortgage servicing rights	219,254,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Mortgage derivative instruments
Assets measured at fair value on a nonrecurring basis
Derivative financial instruments, assets	11,214,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Minimum | Residential mortgage-backed securities
Assets measured at fair value on a nonrecurring basis
Constant prepayment rates (as a percent)	1.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | Minimum | Mortgage servicing rights
Assets measured at fair value on a nonrecurring basis
Constant prepayment rates (as a percent)	10.40%
Discount rate	9.25%
Maturity	299 months
Delinquencies	0.25%
Cost to services	60
Cost to services - deliquent	100
Significant Unobservable Inputs (Level 3) | Recurring basis | Minimum | Mortgage derivative instruments
Assets measured at fair value on a nonrecurring basis
Expected closing ratio	65.00%
Expected delivery price	0.99%
Significant Unobservable Inputs (Level 3) | Recurring basis | Maximum | Residential mortgage-backed securities
Assets measured at fair value on a nonrecurring basis
Constant prepayment rates (as a percent)	3.00%
Significant Unobservable Inputs (Level 3) | Recurring basis | Maximum | Mortgage servicing rights
Assets measured at fair value on a nonrecurring basis
Constant prepayment rates (as a percent)	14.20%
Discount rate	12.00%
Maturity	356 months
Delinquencies	5.00%
Cost to services	160
Cost to services - deliquent	$1,000
Significant Unobservable Inputs (Level 3) | Recurring basis | Maximum | Mortgage derivative instruments
Assets measured at fair value on a nonrecurring basis
Expected closing ratio	95.00%
Expected delivery price	1.09%

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 3) (Mortgage servicing rights, USD $)	3 Months Ended
	Mar. 31, 2015
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	($9,979,000)
Impact on fair value of 20% adverse change	-19,144,000
Impact on fair value of 10% adverse change	-7,330,000
Impact on fair value of 20% adverse change	-14,193,000
Impact on fair value of 10% adverse change	-1,310,000
Impact on fair value of 20% adverse change	-1,977,000
Impact on fair value of 10% adverse change	-3,142,000
Impact on fair value of 20% adverse change	-6,284,000
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	13.60%
Weighted average discount rate	9.42%
Weighted average delinquency rate	0.98%
Weighted average costs to service	$70

Fair_Value_Measurements_Detail3

Fair Value Measurements (Details 4) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Fair value assumption, allowance for impaired real estate loans percentage	90.00%
Investment securities
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance, beginning of period	$973	$5,856
Purchases	0	0
Originations	0	0
Other comprehensive income	0	-179
Included in earnings	0	0
Principal payments	-38	-178
Balance, ending of period	935	5,499
Mortgage servicing rights
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance, beginning of period	235,402	0
Purchases	85	0
Originations	16,560	0
Other comprehensive income	0	0
Included in earnings	-32,793	0
Principal payments	0	0
Balance, ending of period	219,254	0
Mortgage derivative instruments
Financial assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance, beginning of period	5,074	0
Purchases	0	0
Originations	0	0
Other comprehensive income	0	0
Included in earnings	6,140	0
Principal payments	0	0
Balance, ending of period	$11,214	$0

Fair_Value_Measurements_Detail4

Fair Value Measurements (Details 5) (Nonrecurring basis, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial Assets:
Impaired loans	$61,757	$61,717
Foreclosed assets	39,889	38,619
Significant Unobservable Inputs (Level 3)
Financial Assets:
Impaired loans	61,757	61,717
Foreclosed assets	$39,889	$38,619
Significant Unobservable Inputs (Level 3) | Maximum
Financial Assets:
Appraisal adjustment impaired loans (as a percent)	10.00%
Appraisal adjustment foreclosed assets (as a percent)	10.00%
Significant Unobservable Inputs (Level 3) | Minimum
Financial Assets:
Appraisal adjustment impaired loans (as a percent)	5.00%
Appraisal adjustment foreclosed assets (as a percent)	5.00%

Fair_Value_Measurements_Detail5

Fair Value Measurements (Details 6) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
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
Financial Assets:
Cash and due from banks	$248,840	$256,804
Interest bearing deposits with banks	52,212	55,277
Investment securities available for sale	1,589,424	1,654,752
Investment securities held to maturity	1,045,205	1,035,061
Non-marketable securities - FHLB and FRB stock	87,677	75,569
Loans held for sale	686,838	737,209
Derivative financial instruments	21,660	13,952
Financial Liabilities:
Noninterest bearing deposits	4,290,499	4,118,256
Interest bearing deposits	6,729,002	6,872,686
Short-term borrowings	615,231	931,415
Junior subordinated notes issued to capital trusts	185,874	185,778
Derivative financial instruments	44,979	37,927
Carrying Amount
Financial Assets:
Cash and due from banks	248,840	256,804
Interest bearing deposits with banks	52,212	55,277
Investment securities available for sale	1,589,424	1,654,752
Investment securities held to maturity	1,000,859	993,380
Non-marketable securities - FHLB and FRB stock	87,677	75,569
Loans held for sale	686,838	737,209
Loans, net	8,807,916	8,973,191
Accrued interest receivable	46,532	49,065
Derivative financial instruments	68,283	46,388
Financial Liabilities:
Noninterest bearing deposits	4,290,499	4,118,256
Interest bearing deposits	6,729,002	6,872,686
Short-term borrowings	615,231	931,415
Long-term borrowings	85,477	82,916
Junior subordinated notes issued to capital trusts	185,874	185,778
Accrued interest payable	3,005	3,709
Derivative financial instruments	47,162	40,499
Total Fair Value
Financial Assets:
Cash and due from banks	248,840	256,804
Interest bearing deposits with banks	52,212	55,277
Investment securities available for sale	1,589,424	1,654,752
Investment securities held to maturity	1,045,205	1,035,061
Non-marketable securities - FHLB and FRB stock	87,677	75,569
Loans held for sale	686,838	737,209
Loans, net	8,870,489	8,956,494
Accrued interest receivable	46,532	49,065
Derivative financial instruments	68,283	46,388
Financial Liabilities:
Noninterest bearing deposits	4,290,499	4,118,256
Interest bearing deposits	6,734,854	6,877,349
Short-term borrowings	615,216	931,415
Long-term borrowings	88,299	86,025
Junior subordinated notes issued to capital trusts	123,059	122,408
Accrued interest payable	3,005	3,709
Derivative financial instruments	47,162	40,499
Recurring basis
Financial Assets:
Loans held for sale	686,838	737,209
Derivative financial instruments	68,283	46,388
Financial Liabilities:
Derivative financial instruments	47,162	40,499
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets:
Cash and due from banks	248,840	256,804
Interest bearing deposits with banks	52,212	55,277
Investment securities available for sale	10,751	10,597
Investment securities held to maturity	0	0
Non-marketable securities - FHLB and FRB stock	0	0
Loans held for sale	0	0
Loans, net	0	0
Accrued interest receivable	46,532	49,065
Derivative financial instruments	6,427	1,607
Financial Liabilities:
Noninterest bearing deposits	4,290,499	4,118,256
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	3,005	3,709
Derivative financial instruments	8,235	7,209
Recurring basis | Significant Other Observable Inputs (Level 2)
Financial Assets:
Cash and due from banks	0	0
Interest bearing deposits with banks	0	0
Investment securities available for sale	1,577,738	1,643,182
Investment securities held to maturity	1,045,205	1,035,061
Non-marketable securities - FHLB and FRB stock	0	0
Loans held for sale	686,838	737,209
Loans, net	20,829	0
Accrued interest receivable	0	0
Derivative financial instruments	50,642	39,707
Financial Liabilities:
Noninterest 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	38,927	33,290
Recurring basis | Significant Unobservable Inputs (Level 3)
Financial Assets:
Cash and due from banks	0	0
Interest bearing deposits with banks	0	0
Investment securities available for sale	935	973
Investment securities held to maturity	0	0
Non-marketable securities - FHLB and FRB stock	87,677	75,569
Loans held for sale	0	0
Loans, net	8,849,660	8,956,494
Accrued interest receivable	0	0
Derivative financial instruments	11,214	5,074
Financial Liabilities:
Noninterest bearing deposits	0	0
Interest bearing deposits	6,734,854	6,877,349
Short-term borrowings	615,216	931,415
Long-term borrowings	88,299	86,025
Junior subordinated notes issued to capital trusts	123,059	122,408
Accrued interest payable	0	0
Derivative financial instruments	$0	$0

Stock_Incentive_Plans_Details

Stock Incentive Plans (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Impact of the share-based payment plans in the financial statements
Total cost of share-based payment plans during the period	$3,605	$2,012
Amount of related income tax benefit recognized in income	1,412	790
Restricted shares
Changes in restricted shares
Number of Shares and Units, Shares Outstanding, Beginning balance	801,085
Number of Shares and Units, Granted	490,504
Number of Shares and Units, Vested	-94,740
Number of Shares and Units, Forfeited	-3,539
Number of Shares and Units, Shares Outstanding, Ending balance	1,193,310
Weighted Average Grant Date Fair Value, restricted shares
Weighted Average Grant Date Fair Value, Shares Outstanding, Beginning balance (in dollars per share)	$26.99
Weighted Average Grant Date Fair Value, Granted (in dollars per share)	$31.65
Weighted Average Grant Date Fair Value, Vested (in dollars per share)	$27.74
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share)	$27.08
Weighted Average Grant Date Fair Value, Shares Outstanding, Ending balance (in dollars per share)	$28.85
Employee stock options
Options outstanding activity
Number of Options, Outstanding, Beginning balance	2,250,714
Number of Options, Granted	296,413
Number of Options, Exercised	-7,284
Number of Options, Expired or Cancelled	-3,933
Number of Options, Forfeited	-2,928
Number of Options, Outstanding, Ending balance	2,532,982		2,250,714
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding, Beginning balance (in dollars per share)	$27.94
Weighted Average Exercise Price, Granted (in dollars per share)	$31.26
Weighted Average Exercise Price, Exercised (in dollars per share)	$19.85
Weighted Average Exercise Price, Expired or Cancelled (in dollars per share)	$30.34
Weighted Average Exercise Price, Forfeited (in dollars per share)	$25
Weighted Average Exercise Price, Outstanding, Ending balance (in dollars per share)	$28.35		$27.94
Weighted Average Remaining Contractual Term (In Years)
Weighted Average Remaining Contractual Term, Beginning balance (in years)	4 years 9 months 22 days		4 years 4 months 20 days
Weighted Average Remaining Contractual Term, Ending balance (in years)	4 years 9 months 22 days		4 years 4 months 20 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Options Outstanding	11,342
Options Exercisable, Number (in shares)	1,729,575
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$29.07
Options Exercisable, Weighted Average Remaining Contractual Term (in years)	3 years 1 month 15 days
Options Exercisable, Aggregate Intrinsic Value	$7,723
Fair value assumptions
Risk-free interest rate	1.71%
Expected volatility of Company’s stock	30.43%
Expected dividend yield	1.79%
Expected life of options	5 years 11 months 10 days
Weighted average fair value per option of options granted during the year	$8.08

Stock_Incentive_Plans_Details_

Stock Incentive Plans (Details 2) (USD $)	3 Months Ended	0 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2015	28-May-14	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation
Grants beyond threshold limit count numerator	2
Grants beyond threshold limit count denominator	1
Omnibus Incentive Plan
Stock-based compensation
Additional number of share authorized		3,100,000
Total number of shares authorized		11,400,000
Percentage of shares authorized for issuance		10.00%
Vesting period		3 years
Shares available for future grant	4,979,712
Unrecognized compensation cost related to nonvested share-based compensation	31,600,000
Period for recognition	2 years 8 months 10 days
Employee stock options
Stock-based compensation
Award requisite service period	4 years
Expiration term of options	10 years
Intrinsic value of options exercised	81,000		550,000
Restricted shares
Stock-based compensation
Intrinsic value of restricted shares that vested	3,000,000		$1,000,000
Restricted shares | Minimum
Stock-based compensation
Vesting period	2 years
Restricted shares | Maximum
Stock-based compensation
Vesting period	4 years
Performance-based restricted stock units
Stock-based compensation
Restricted stock issued (in shares)	71,560			48,569	56,752	65,333
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%
Taylor Capital Group, Inc. | Omnibus Incentive Plan
Stock-based compensation
Total number of shares authorized	13,800,000
Increase in amount of shares authorized	2,400,000
Director | Restricted stock
Stock-based compensation
Vesting period	1 year
Maximum percentage of directors fees with option to be received in equity based incentive awards	100.00%
Director | Employee stock options
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

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Details) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Derivative [Line Items]
Net amount payable under interest rate swap	$3,000			$1,100,000
Interest rate swap credit risk exposure	33,700,000
Asset Derivatives, Notional Amount	3,694,708,000			2,465,120,000
Asset Derivatives, Estimated Fair Value	68,283,000			46,388,000
Liability Derivatives, Notional Amount	2,654,246,000			2,964,961,000
Liability Derivatives, Estimated Fair Value	-47,162,000			-40,499,000
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	12,851,000		81,000
Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	3,694,708,000	[1]		2,465,120,000	[1]
Asset Derivatives, Estimated Fair Value	68,283,000	[1]		46,388,000	[1]
Liability Derivatives, Notional Amount	2,654,059,000	[1]		2,964,764,000	[1]
Liability Derivatives, Estimated Fair Value	-47,148,000	[1]		-40,484,000	[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	12,850,000		81,000
Commercial loan interest rate swaps
Derivative [Line Items]
Liability Derivatives, Notional Amount	187,000
Interest rate swap contracts | Derivative instruments designated as hedges of fair value
Derivative [Line Items]
Asset Derivatives, Notional Amount	0	[1]		0	[1]
Asset Derivatives, Estimated Fair Value	0	[1]		0	[1]
Liability Derivatives, Notional Amount	187,000	[2]		197,000	[2]
Liability Derivatives, Estimated Fair Value	-14,000	[2]		-15,000	[2]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Amounts of gain or (loss) recognized in income on derivatives	1,000		0
Interest rate swap contracts | Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	2,072,809,000	[1]		1,509,930,000	[1]
Asset Derivatives, Estimated Fair Value	50,633,000	[1]		37,039,000	[1]
Liability Derivatives, Notional Amount	1,268,604,000	[1]		2,001,787,000	[1]
Liability Derivatives, Estimated Fair Value	-34,942,000	[1]		-30,761,000	[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	11,125,000		9,000
Interest rate options contracts | Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	617,089,000	[1]		55,830,000	[1]
Asset Derivatives, Estimated Fair Value	982,000	[1]		283,000	[1]
Liability Derivatives, Notional Amount	67,089,000	[1]		55,830,000	[1]
Liability Derivatives, Estimated Fair Value	-260,000	[1]		-283,000	[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	723,000		0
Foreign exchange contracts | Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	49,017,000	[1]		27,402,000	[1]
Asset Derivatives, Estimated Fair Value	4,470,000	[1]		2,276,000	[1]
Liability Derivatives, Notional Amount	46,904,000	[1]		27,002,000	[1]
Liability Derivatives, Estimated Fair Value	-4,181,000	[1]		-2,109,000	[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	122,000		61,000
Spot foreign exchange contract | Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	210,000	[1]		512,000	[1]
Asset Derivatives, Estimated Fair Value	6,000	[1]		5,000	[1]
Liability Derivatives, Notional Amount	462,000	[1]		304,000	[1]
Liability Derivatives, Estimated Fair Value	-46,000	[1]		-18,000	[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	-28,000		8,000
Mortgage related derivatives | Stand-alone derivative instruments
Derivative [Line Items]
Asset Derivatives, Notional Amount	955,583,000	[1]		871,446,000	[1]
Asset Derivatives, Estimated Fair Value	12,192,000	[1]		6,785,000	[1]
Liability Derivatives, Notional Amount	1,271,000,000	[1]		879,841,000	[1]
Liability Derivatives, Estimated Fair Value	-7,719,000	[1]		-7,313,000	[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	$908,000		$3,000
[1]	These portfolio swaps are not designated as hedging instruments under ASC Topic 815.
[2]	Hedged fixed-rate commercial real estate loans

Derivative_Financial_Instrumen3

Derivative Financial Instruments (Details 2) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Financial Assets, Gross Amount Recognized	$21,660	$13,952
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	21,660	13,952
Financial Liabilities, Gross Amount Recognized	44,979	37,927
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	44,979	37,927
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
Repurchase Agreements, Financial Liabilities, Gross Amount Recognized	240,478	219,824
Repurchase Agreements, Financial Liabilities, Gross Amount Offset	0	0
Repurchase Agreements, Financial Liabilities, Net Amount Recognized	240,478	219,824
Total Financial Assets, Gross Amount Recognized	21,660	13,952
Total Financial Assets, Gross Amount Offset	0	0
Total Financial Assets, Net Amount Recognized	21,660	13,952
Total Financial Liabilities, Gross Amount Recognized	285,457	257,751
Total Financial Liabilities, Gross Amount Offset	0	0
Total Financial Liabilities, Net Amount Recognized	285,457	257,751
Interest rate swaps, caps and floors
Derivative [Line Items]
Financial Assets, Gross Amount Recognized	17,959	10,727
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	17,959	10,727
Financial Liabilities, Gross Amount Recognized	34,795	29,916
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	34,795	29,916
Foreign currency forward contracts
Derivative [Line Items]
Financial Assets, Gross Amount Recognized	2,307	1,525
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	2,307	1,525
Financial Liabilities, Gross Amount Recognized	2,050	709
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	2,050	709
Mortgage related derivatives
Derivative [Line Items]
Financial Assets, Gross Amount Recognized	1,394	1,700
Financial Assets, Gross Amount Offset	0	0
Financial Assets, Net Amount Recognized	1,394	1,700
Financial Liabilities, Gross Amount Recognized	8,134	7,302
Financial Liabilities, Gross Amount Offset	0	0
Financial Liabilities, Net Amount Recognized	$8,134	$7,302

Derivative_Financial_Instrumen4

Derivative Financial Instruments (Details 3) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Financial Assets, Net Amount Recognized	$21,660	$13,952
Financial Assets, Financial Instruments	-16,755	-10,201
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	4,905	3,751
Financial Liabilities, Net Amount Recognized	44,979	37,927
Financial Liabilities, Financial Instruments	-16,756	-10,200
Financial Liabilities, Collateral	-26,691	-26,010
Financial Liabilities, Net Amount	1,532	1,717
Repurchase Agreements, Financial Assets, Net Amount Recognized	0	0
Repurchase Agreements, Financial Assets, Financial Instruments	0	0
Repurchase Agreements, Financial Assets, Collateral	0	0
Repurchase Agreements, Financial Assets, Net Amount	0	0
Repurchase Agreements, Financial Liabilities, Net Amount Recognized	240,478	219,824
Repurchase Agreements, Financial Liabilities, Financial Instruments	0	0
Repurchase Agreements, Financial Liabilities, Financial Instruments	-240,478	-219,824
Repurchase Agreements, Financial Liabilities, Collateral	0	0
Total Financial Assets, Net Amount Recognized	21,660	13,952
Total Financial Assets, Financial Instruments	-16,755	-10,201
Total Financial Assets, Collateral	0	0
Total Financial Assets, Net Amount	4,905	3,751
Total Financial Liabilities, Net Amount Recognized	285,457	257,751
Total Financial Liabilities, Financial Instruments	-16,756	-10,200
Total Financial Liabilities, Collateral	-267,169	-245,834
Total Financial Liabilities, Net Amount	1,532	1,717
Counterparty A
Derivative [Line Items]
Financial Assets, Net Amount Recognized	19	13
Financial Assets, Financial Instruments	-19	-13
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	0	0
Financial Liabilities, Net Amount Recognized	10,604	9,556
Financial Liabilities, Financial Instruments	-19	-13
Financial Liabilities, Collateral	-10,585	-9,543
Financial Liabilities, Net Amount	0	0
Counterparty B
Derivative [Line Items]
Financial Assets, Net Amount Recognized	27	145
Financial Assets, Financial Instruments	-27	-145
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	0	0
Financial Liabilities, Net Amount Recognized	4,962	3,736
Financial Liabilities, Financial Instruments	-27	-145
Financial Liabilities, Collateral	-4,935	-3,591
Financial Liabilities, Net Amount	0	0
Counterparty C
Derivative [Line Items]
Financial Assets, Net Amount Recognized	9,792	6,123
Financial Assets, Financial Instruments	-9,792	-6,123
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	0	0
Financial Liabilities, Net Amount Recognized	13,218	10,335
Financial Liabilities, Financial Instruments	-9,792	-6,122
Financial Liabilities, Collateral	-3,426	-4,213
Financial Liabilities, Net Amount	0	0
Other counterparties
Derivative [Line Items]
Financial Assets, Net Amount Recognized	11,822	7,671
Financial Assets, Financial Instruments	-6,917	-3,920
Financial Assets, Collateral	0	0
Financial Assets, Net Amount	4,905	3,751
Financial Liabilities, Net Amount Recognized	16,195	14,300
Financial Liabilities, Financial Instruments	-6,918	-3,920
Financial Liabilities, Collateral	-7,745	-8,663
Financial Liabilities, Net Amount	$1,532	$1,717

Operating_Segments_Details

Operating Segments (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
	segment
Segment Reporting Information [Line Items]
Reportable Segments Number	3
Net interest income	$113,395,000		$67,328,000
Provision for credit losses	4,974,000		1,150,000
Non-interest income	81,268,000		36,612,000
Non-interest expense	139,920,000	[1]	76,047,000
Income tax expense	15,658,000		6,774,000
Net income	34,111,000		19,969,000
Total assets	14,328,310,000		9,437,303,000	14,602,099,000
Taylor Capital Group, Inc.
Segment Reporting Information [Line Items]
Pretax merger related costs	8,100,000		680,000
Banking
Segment Reporting Information [Line Items]
Net interest income	104,126,000		66,324,000
Provision for credit losses	4,974,000		1,150,000
Non-interest income	31,517,000		23,701,000
Non-interest expense	95,334,000	[1]	68,334,000
Income tax expense	9,962,000		4,483,000
Net income	25,373,000		16,058,000
Total assets	12,246,659,000		8,968,195,000
Leasing
Segment Reporting Information [Line Items]
Net interest income	3,015,000		1,004,000
Provision for credit losses	0		0
Non-interest income	25,203,000		12,852,000
Non-interest expense	13,656,000	[1]	7,713,000
Income tax expense	5,747,000		2,291,000
Net income	8,815,000		3,852,000
Total assets	937,903,000		469,108,000
Mortgage Banking
Segment Reporting Information [Line Items]
Net interest income	6,254,000		0
Provision for credit losses	0		0
Non-interest income	24,548,000		59,000
Non-interest expense	30,930,000	[1]	0
Income tax expense	-51,000		0
Net income	-77,000		59,000
Total assets	$1,143,748,000		$0
[1]	Includes merger related expenses of $8.1 million and $680 thousand in the banking segment for the three months ended March 31, 2015 and 2014, respectively.

Preferred_Stock_Details

Preferred Stock (Details) (USD $)	0 Months Ended	3 Months Ended	12 Months Ended
	Aug. 18, 2014	Mar. 31, 2015	Dec. 31, 2014	Aug. 18, 2014
Equity [Abstract]
Stock conversion	1
Preferred stock, shares outstanding		4,000,000	4,000,000	4,000,000
Preferred stock, liquidation preference per share (in dollars per share)		$25	$25
Preferred stock, dividend rate, percentage		8.00%	8.00%