Associated Banc-Corp (ASB) 10-Q 28 Apr 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 27, 2016
Document And Entity Information [Abstract]
Trading Symbol	ASB
Entity Registrant Name	ASSOCIATED BANC-CORP
Entity Central Index Key	7,789
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		150,136,403

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
ASSETS
Cash and due from banks		$ 287,183	$ 374,921
Interest-bearing deposits in other financial institutions		68,025	79,764
Federal funds sold and securities purchased under agreements to resell		20,200	19,000
Investment securities held to maturity, at amortized cost		1,176,821	1,168,230
Investment securities available for sale, at fair value		4,905,841	4,967,414
Federal Home Loan Bank and Federal Reserve Bank stocks, at cost		181,853	147,240
Loans held for sale		128,339	124,915
Loans		19,227,240	18,714,343
Allowance for loan losses		(277,370)	(274,264)
Loans, net		18,949,870	18,440,079
Premises and equipment, net		331,711	267,606
Goodwill		971,951	968,844
Mortgage servicing rights		59,414	61,341
Other intangible assets		16,966	16,458
Trading assets		53,087	32,192
Other assets	[1]	1,027,606	1,043,831
Total assets		28,178,867	27,711,835
LIABILITIES AND STOCKHOLDERS’ EQUITY
Noninterest-bearing demand deposits		5,272,685	5,562,466
Interest-bearing deposits		15,412,775	15,445,199
Total deposits		20,685,460	21,007,665
Federal funds purchased and securities sold under agreements to repurchase		583,247	431,438
Other short-term funding		834,161	402,978
Long-term funding	[1]	2,861,316	2,676,164
Trading liabilities		55,223	33,430
Accrued expenses and other liabilities		176,962	222,914
Total liabilities		25,196,369	24,774,589
Stockholders’ equity
Preferred equity		120,347	121,379
Common stock		1,630	1,642
Surplus		1,447,368	1,458,522
Retained earnings		1,599,835	1,593,239
Accumulated other comprehensive loss		2,167	(32,616)
Treasury stock, at cost		(188,849)	(204,920)
Total common equity		2,862,151	2,815,867
Total stockholders’ equity		2,982,498	2,937,246
Total liabilities and stockholders’ equity		$ 28,178,867	$ 27,711,835
Preferred shares issued (in shares)		124,054	125,114
Preferred shares authorized (par value $1.00 per share) (in shares)		750,000	750,000
Common shares issued (in shares)		163,030,209	164,200,068
Common shares authorized (par value $0.01 per share) (in shares)		250,000,000	250,000,000
Treasury shares of common stock (in shares)		12,036,645	12,960,636
[1]	During the first quarter of 2016, the Corporation adopted a new accounting standard related to simplifying the presentation of debt issuance costs. Under this new accounting standard, debt issuance costs are still capitalized; however, they are reflected on the balance sheet with the related debt issued rather than within other assets. All prior periods have been restated to reflect this change in presentation. See Note 3 for additional information on this new accounting standard.

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
INTEREST INCOME
Interest and fees on loans	$ 159,656	$ 151,945
Interest and dividends on investment securities:
Taxable	25,516	25,092
Tax exempt	7,830	7,887
Other interest	1,067	1,692
Total interest income	194,069	186,616
INTEREST EXPENSE
Interest on deposits	11,766	7,619
Interest on Federal funds purchased and securities sold under agreements to repurchase	296	231
Interest on other short-term funding	515	81
Interest on long-term funding	9,505	10,872
Total interest expense	22,082	18,803
NET INTEREST INCOME	171,987	167,813
Provision for credit losses	20,000	4,500
Net interest income after provision for credit losses	151,987	163,313
NONINTEREST INCOME
Trust service fees	11,447	12,087
Service charges on deposit accounts	16,273	15,806
Card-based and other nondeposit fees	11,991	12,416
Insurance commissions	21,382	19,728
Brokerage and annuity commissions	3,794	3,683
Mortgage banking, net	4,204	7,408
Capital market fees, net	3,538	2,467
Bank owned life insurance income	4,770	2,875
Asset gains, net	524	833
Investment securities gains, net	3,098	0
Other	2,171	2,510
Total noninterest income	83,192	79,813
NONINTEREST EXPENSE
Personnel expense	101,398	100,152
Occupancy	13,802	17,683
Equipment	5,446	5,772
Technology	14,264	15,558
Business development and advertising	8,211	5,327
Other intangible amortization	504	801
Loan expense	3,221	2,996
Legal and professional fees	5,025	4,538
Foreclosure / OREO expense	1,877	1,162
FDIC expense	7,750	6,500
Other	12,473	13,503
Total noninterest expense	173,971	173,992
Income before income taxes	61,208	69,134
Income tax expense	18,674	22,462
Net income	42,534	46,672
Preferred stock dividends	2,198	1,228
Net income available to common equity	$ 40,336	$ 45,444
Earnings per common share:
Basic (in usd per share)	$ 0.27	$ 0.30
Diluted (in usd per share)	$ 0.27	$ 0.30
Average common shares outstanding:
Basic (in shares)	148,601	150,070
Diluted (in shares)	149,454	151,164

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred shares, par value	$ 1	$ 1
Common shares, par value	$ 0.01	$ 0.01

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 42,534	$ 46,672
Investment securities available for sale:
Net unrealized gains (losses)	60,422	47,418
Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities	(1,572)	0
Reclassification adjustment for net gains realized in net income	(3,098)	0
Income tax (expense) benefit	(21,275)	(18,105)
Other comprehensive income (loss) on investment securities available for sale	34,477	29,313
Defined benefit pension and postretirement obligations:
Prior service cost, net of amortization	13	13
Amortization of actuarial losses	482	532
Income tax (expense) benefit	(189)	(208)
Other comprehensive income (loss) on pension and postretirement obligations	306	337
Comprehensive income	77,317	76,322
Total other comprehensive income (loss)	$ 34,783	$ 29,650

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Equity [Member]	Common Stock [Member]	Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2014	$ 2,800,251	$ 59,727	$ 1,665	$ 1,484,933	$ 1,497,818	$ (4,850)	$ (239,042)
Comprehensive income:
Net income	46,672	0	0	0	46,672	0	0
Other comprehensive income	29,650	0	0	0	0	29,650	0
Comprehensive income	76,322
Common stock issued:
Stock-based compensation plans, net	6,236	0	0	304	(18,015)	0	23,947
Acquisition of Ahmann & Martin Co.	43,530	0	26	43,504	0	0	0
Purchase of treasury stock	(4,105)	0	0	0	0	0	(4,105)
Cash dividends:
Common stock dividends ($0.10 per share in 2015 and $0.11 per share in 2016)	(15,280)	0	0	0	(15,280)	0	0
Preferred stock dividends	(1,228)	0	0	0	(1,228)	0	0
Stock-based compensation expense, net	5,774	0	0	5,774	0	0	0
Tax impact of stock-based compensation	638	0	0	638	0	0	0
Purchase of common stock returned to authorized but unissued	(30,000)	0	(17)	(29,983)	0	0	0
Ending balance at Mar. 31, 2015	2,882,138	59,727	1,674	1,505,170	1,509,967	24,800	(219,200)
Beginning balance at Dec. 31, 2015	2,937,246	121,379	1,642	1,458,522	1,593,239	(32,616)	(204,920)
Comprehensive income:
Net income	42,534	0	0	0	42,534	0	0
Other comprehensive income	34,783	0	0	0	0	34,783	0
Comprehensive income	77,317
Common stock issued:
Stock-based compensation plans, net	2,205	0	0	613	(17,271)	0	18,863
Purchase of treasury stock	(2,792)	0	0	0	0	0	(2,792)
Cash dividends:
Common stock dividends ($0.10 per share in 2015 and $0.11 per share in 2016)	(16,409)	0	0	0	(16,409)	0	0
Preferred stock dividends	(2,198)	0	0	0	(2,198)	0	0
Purchase of preferred stock	(1,092)	(1,032)	0	0	(60)	0	0
Stock-based compensation expense, net	8,066	0	0	8,066	0	0	0
Tax impact of stock-based compensation	162	0	0	162	0	0	0
Purchase of common stock returned to authorized but unissued	(20,007)	0	(12)	(19,995)	0	0	0
Ending balance at Mar. 31, 2016	$ 2,982,498	$ 120,347	$ 1,630	$ 1,447,368	$ 1,599,835	$ 2,167	$ (188,849)

Consolidated Statements of Cha7

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Common Stock [Member]
Cash dividends:
Common stock, per share	$ 0.11	$ 0.10

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 42,534	$ 46,672
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	20,000	4,500
Depreciation and amortization	11,060	12,268
(Recovery of) addition to valuation allowance on mortgage servicing rights, net	909	243
Amortization of mortgage servicing rights	2,874	3,179
Amortization of other intangible assets	504	801
Amortization and accretion on earning assets, funding, and other, net	10,692	9,863
Tax impact of stock based compensation	162	638
Gain on sales of investment securities, net	(3,098)	0
Gain on sales of assets and impairment write-downs, net	(524)	(833)
Gain on mortgage banking activities, net	(3,106)	(3,141)
Mortgage loans originated and acquired for sale	(193,849)	(268,296)
Proceeds from sales of mortgage loans held for sale	221,764	238,399
(Increase) decrease in interest receivable	(5,180)	(2,186)
Increase (decrease) in interest payable	(6,121)	(948)
Commercial loans held for sale	(30,089)	0
Other, net	(46,160)	(29,848)
Net cash provided by operating activities	22,372	11,311
CASH FLOWS FROM INVESTING ACTIVITIES
Net increase in loans	(531,891)	(368,794)
Purchases of:
Available for sale securities	(182,895)	(202,615)
Held to maturity securities	(28,570)	(36,788)
Federal Home Loan Bank and Federal Reserve Bank stocks	(34,613)	(115)
Premises, equipment, and software, net of disposals	(70,685)	(13,944)
Other assets	(1,226)	(1,207)
Proceeds from:
Sales of available for sale securities	119,379	289
Prepayments, calls, and maturities of available for sale investment securities	180,458	282,835
Prepayments, calls, and maturities of held to maturity investment securities	15,029	5,155
Sales, prepayments, calls, and maturities of other assets	9,566	0
Net cash (paid) received in acquisition	(685)	1,202
Net cash used in investing activities	(526,133)	(333,982)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in deposits	(322,205)	1,088,088
Net increase (decrease) in short-term funding	582,992	(405,751)
Repayment of long-term funding	(430,010)	(500,009)
Proceeds from issuance of long-term funding	615,000	0
Proceeds from issuance of common stock for stock-based compensation plans	2,205	6,236
Purchase of preferred stock	(1,092)	0
Purchase of common stock returned to authorized but unissued	(20,007)	(30,000)
Purchase of treasury stock	(2,792)	(4,105)
Cash dividends on common stock	(16,409)	(15,280)
Cash dividends on preferred stock	(2,198)	(1,228)
Net cash provided by financing activities	405,484	137,951
Net increase (decrease) in cash and cash equivalents	(98,277)	(184,720)
Cash and cash equivalents at beginning of period	473,685	1,032,067	$ 1,032,067
Cash and cash equivalents at end of period	375,408	847,347	$ 473,685
Supplemental disclosures of cash flow information:
Cash paid for interest	28,041	19,643
Cash paid for income taxes	1,167	0
Loans and bank premises transferred to other real estate owned	3,160	2,104
Capitalized mortgage servicing rights	1,856	3,010
Fair value of assets acquired, including cash and cash equivalents	522	5,160
Fair value ascribed to goodwill and intangible assets	4,119	51,221
Fair value of liabilities assumed	1,423	12,851
Common stock issued in acquisition	$ 0	$ 43,530

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly the financial position, results of operations and comprehensive income, changes in stockholders’ equity, and cash flows of Associated Banc-Corp (individually referred to herein as the “Parent Company,” and together with all of its subsidiaries and affiliates, collectively referred to herein as the “Corporation”) for the periods presented, and all such adjustments are of a normal recurring nature. The consolidated financial statements include the accounts of all subsidiaries. All significant intercompany transactions and balances have been eliminated in consolidation. The results of operations for the interim periods are not necessarily indicative of the results to be expected for the full year. In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the balance sheet and revenues and expenses for the period. Actual results could differ significantly from those estimates. Estimates that are particularly susceptible to significant change include the determination of the allowance for loan losses, goodwill impairment assessment, mortgage servicing rights valuation, and income taxes. Management has evaluated subsequent events for potential recognition or disclosure. During the first quarter of 2016, the consolidated statements of income were modified from prior periods' presentation to conform with the current period presentation, which reflects OREO gains / losses as a component of Foreclosure / OREO expense, net. In prior periods' presentation, OREO gains/losses were reported as a component of asset gains (losses), net. All prior periods have been restated to reflect this change. During the first quarter of 2016, the Corporation combined the lease financing portfolio with the commercial and industrial portfolio for disclosure purposes. All prior periods have been restated to reflect this change in presentation.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Acquisitions	Acquisitions On February 17, 2015, the Corporation acquired Ahmann & Martin Co., a risk and employee benefits consulting firm based in Minnesota. The firm merged into Associated Financial Group, LLC, the Corporation's insurance brokerage subsidiary. The Corporation's acquisition of Ahmann & Martin Co. enhances the Corporation's ability to offer clients unique, comprehensive solutions to meet their insurance and financial risk management needs. The transaction was valued at approximately $48 million with the opportunity to increase the consideration by $8 million should certain contingencies be met over a defined period. The transaction was accounted for using the acquisition method of accounting and as such, assets acquired, liabilities assumed and consideration exchanged were recorded at their estimated fair value on the acquisition date. Goodwill from the acquisition represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired and is not deductible for tax purposes. As a result of the acquisition, the Corporation recorded goodwill of approximately $40 million and other intangible assets of approximately $12 million . Goodwill was assigned to the Corporation's Community, Consumer, and Business segment. See Note 8 for additional information on goodwill and other intangible assets. During the first quarter of 2016, the Corporation completed two small insurance acquisitions to complement its existing insurance and benefits related products and services provided by Associated Financial Group, LLC. The Corporation recorded goodwill of $3 million and other intangibles of $1 million related to these insurance acquisitions.

New Accounting Pronouncements A

New Accounting Pronouncements Adopted	3 Months Ended
	Mar. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements Adopted	New Accounting Pronouncements Adopted In September 2015, the FASB issued an amendment to simplify the accounting for measurement adjustments to prior business combinations. The amendment requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The acquirer must record, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendment also requires an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. This amendment was effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The Corporation adopted the accounting standard during the first quarter of 2016, as required, and with no material impact on its results of operations, financial position, or liquidity. In May 2015, the FASB issued an amendment to eliminate the requirement to categorize investments measured using the net asset value per share ("NAV") practical expedient in the fair value hierarchy table. Entities will be required to disclose the fair value of investments measured using the NAV practical expedient so that financial statement users can reconcile amounts reported in the fair value hierarchy table to amounts reported on the balance sheet. The Corporation adopted the accounting standard during the first quarter of 2016, as required, with no material impact on its results of operations, financial position, or liquidity. In April 2015, the FASB issued an amendment to provide guidance to customers about whether a cloud computing arrangement included a software license. If the cloud computing arrangement includes a software license, then the customer should account for the software license element consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. This amendment was effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. The Corporation adopted the accounting standard on a prospective basis during the first quarter of 2016, as required, and with no material impact on its results of operations, financial position, or liquidity. In April 2015, the FASB issued an amendment to simplify the presentation of debt issuance costs. This amendment requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. In August 2015, the FASB expanded this amendment to include SEC staff views related to debt issuance costs associated with line-of-credit arrangements. The SEC staff would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. This amendment required retrospective application and was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The Corporation adopted the accounting standard during the first quarter of 2016. All prior periods have been restated to reflect this change in presentation, resulting in a $3 million reduction to other assets and a corresponding $3 million reduction to long-term funding on the balance sheet compared to the amounts originally reported at December 31, 2015. See "Consolidated Balance Sheets" and Note 9 for additional information on the reclassification of debt issuance costs. In February 2015, the FASB issued an amendment to modify existing consolidation guidance for reporting companies that are required to evaluate whether they should consolidate legal entities. The new standard will place more emphasis on risk of loss when determining a controlling financial interest. Frequency in the application of related-party guidance for determining a controlling financial interest will be reduced. Also, consolidation conclusions for public and private companies among several industries that make use of limited partnerships or VIEs will be changed. This amendment was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The Corporation adopted the accounting standard during the first quarter of 2016, as required, and with no material impact on its results of operations, financial position, or liquidity. In January 2015, the FASB issued an amendment to eliminate from U.S. GAAP the concept of extraordinary items. Presently, an event or transaction is presumed to be an ordinary and usual activity of the reporting entity unless evidence clearly supports its classification as an extraordinary item. If an event or transaction meets the criteria for extraordinary classification, an entity is required to segregate the extraordinary item from the results of ordinary operations and show the item separately in the income statement, net of tax, after income from continuing operations. This amended guidance will prohibit separate disclosure of extraordinary items in the income statement. This amendment was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The Corporation adopted the accounting standard during the first quarter of 2016, as required, with no material impact. In June 2014, the FASB issued an amendment to the stock compensation accounting guidance to clarify that a performance target that affects vesting of a share-based payment and that could be achieved after the requisite service period be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. This amendment was effective for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2015. The Corporation adopted the accounting standard on a prospective basis during the first quarter of 2016, as required, with no material impact on its results of operations, financial position, or liquidity.

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share Earnings per common share are calculated utilizing the two-class method. Basic earnings per common share are calculated by dividing the sum of distributed earnings to common shareholders and undistributed earnings allocated to common shareholders by the weighted average number of common shares outstanding. Diluted earnings per common share are calculated by dividing the sum of distributed earnings to common shareholders and undistributed earnings allocated to common shareholders by the weighted average number of common shares outstanding adjusted for the dilutive effect of common stock awards (outstanding stock options, unvested restricted stock awards, and outstanding common stock warrants). Presented below are the calculations for basic and diluted earnings per common share. For the Three Months Ended March 31, 2016 2015 (In thousands, except per share data) Net income $ 42,534 $ 46,672 Preferred stock dividends (2,198 ) (1,228 ) Net income available to common equity $ 40,336 $ 45,444 Common shareholder dividends (16,203 ) (15,166 ) Unvested share-based payment awards (206 ) (114 ) Undistributed earnings $ 23,927 $ 30,164 Undistributed earnings allocated to common shareholders 23,686 29,886 Undistributed earnings allocated to unvested share-based payment awards 241 278 Undistributed earnings $ 23,927 $ 30,164 Basic Distributed earnings to common shareholders $ 16,203 $ 15,166 Undistributed earnings allocated to common shareholders 23,686 29,886 Total common shareholders earnings, basic $ 39,889 $ 45,052 Diluted Distributed earnings to common shareholders $ 16,203 $ 15,166 Undistributed earnings allocated to common shareholders 23,686 29,886 Total common shareholders earnings, diluted $ 39,889 $ 45,052 Weighted average common shares outstanding 148,601 150,070 Effect of dilutive common stock awards 853 1,094 Diluted weighted average common shares outstanding 149,454 151,164 Basic earnings per common share $ 0.27 $ 0.30 Diluted earnings per common share $ 0.27 $ 0.30 Options to purchase approximately 3 million and 2 million shares were outstanding for the three months ended March 31, 2016 and 2015 , respectively, but excluded from the calculation of diluted earnings per common share as the effect would have been anti-dilutive. Warrants to purchase approximately 4 million shares were outstanding for both three months ended March 31, 2016 and 2015, but excluded from the calculation of diluted earnings per common shares as the effect would have been anti-dilutive.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Stock-Based Compensation	Stock-Based Compensation Stock-Based Compensation Plan: In March 2013, the Board of Directors, with subsequent approval of the Corporation’s shareholders, approved the adoption of the 2013 Incentive Compensation Plan (“2013 Plan”). Under the 2013 Plan, options are generally exercisable up to 10 years from the date of grant, have an exercise price that is equal to the closing price of the Corporation’s stock on the grant date, and vest ratably over four years , while service-based restricted stock awards vest ratably over four years and performance-based restricted stock awards vest over the three year performance period. The Corporation issues restricted common stock and restricted common stock units to certain key employees (collectively referred to as “restricted stock awards”) under this plan. The shares of restricted stock are restricted as to transfer, but are not restricted as to dividend payment or voting rights. Restricted stock units receive dividend equivalents but do not have voting rights. The transfer restrictions lapse over three or four years , depending upon whether the awards are service-based or performance-based. Service-based awards are contingent upon continued employment or meeting the requirements for retirement, and performance-based awards are based on earnings per share performance goals, relative total shareholder return, and continued employment or meeting the requirements for retirement. The plan provides that restricted stock awards and stock options will immediately become fully vested upon retirement from the Corporation of those colleagues whose retirement meets the early retirement or normal retirement definitions under the plan (“retirement eligible colleagues”). Accounting for Stock-Based Compensation: The fair value of stock options granted is estimated on the date of grant using a Black-Scholes option pricing model, while the fair value of restricted stock awards is their fair market value on the date of grant. The fair values of stock options and restricted stock awards are amortized as compensation expense on a straight-line basis over the vesting period of the grants. For retirement eligible colleagues, expenses related to stock options and restricted stock awards are fully recognized on the date the colleague meets the definition of normal or early retirement. Compensation expense recognized is included in personnel expense in the consolidated statements of income. Assumptions are used in estimating the fair value of stock options granted. The weighted average expected life of the stock option represents the period of time that stock options are expected to be outstanding and is estimated using historical data of stock option exercises and forfeitures. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The expected volatility is based on the implied volatility of the Corporation’s stock. The following assumptions were used in estimating the fair value for options granted in the first three months of 2016 and full year 2015 . 2016 2015 Dividend yield 2.50 % 2.00 % Risk-free interest rate 2.00 % 2.00 % Weighted average expected volatility 25.00 % 20.00 % Weighted average expected life 5.5 years 6.0 years Weighted average per share fair value of options $3.36 $3.08 The Corporation is required to estimate potential forfeitures of stock grants and adjust compensation expense recorded accordingly. The estimate of forfeitures will be adjusted over the requisite service period to the extent that actual forfeitures differ, or are expected to differ, from such estimates. Changes in estimated forfeitures will be recognized in the period of change and will also impact the amount of stock-based compensation expense to be recognized in future periods. A summary of the Corporation’s stock option activity for the year ended December 31, 2015 , and the three month ended March 31, 2016 is presented below. Stock Options Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (000s) Outstanding at December 31, 2014 7,847,338 $ 18.34 Granted 1,348,504 17.95 Exercised (1,351,646 ) 13.90 Forfeited or expired (1,215,053 ) 29.13 Outstanding at December 31, 2015 6,629,143 $ 17.22 6.24 $ 18,730 Options Exercisable at December 31, 2015 4,190,245 $ 17.25 4.93 $ 14,873 Granted 1,302,298 $ 17.45 Exercised (96,602 ) 13.60 Forfeited or expired (48,190 ) 17.75 Outstanding at March 31, 2016 7,786,649 $ 17.30 6.61 $ 14,682 Options Exercisable at March 31, 2016 4,907,257 $ 17.22 5.18 $ 12,950 The following table summarizes information about the Corporation’s nonvested stock option activity for the year ended December 31, 2015 , and for the three months ended March 31, 2016 . Nonvested Stock Options Shares Weighted Average Grant Date Fair Value Nonvested at December 31, 2014 2,770,662 $ 3.74 Granted 1,348,504 3.08 Vested (1,459,709 ) 4.19 Forfeited (220,559 ) 3.28 Nonvested at December 31, 2015 2,438,898 $ 3.15 Granted 1,302,298 3.36 Vested (813,614 ) 3.25 Forfeited (48,190 ) 3.20 Nonvested at March 31, 2016 2,879,392 $ 3.21 Intrinsic value represents the amount by which the fair market value of the underlying stock exceeds the exercise price of the stock option. For the three months ended March 31, 2016 , the intrinsic value of stock options exercised was approximately $420,000 . For the year ended December 31, 2015 the intrinsic value of the stock options exercised was $7 million . The total fair value of stock options that vested were $3 million and $6 million , respectively, for the three months ended March 31, 2016 and for the year ended December 31, 2015 . The Corporation recognized compensation expense for the vesting of stock options of over $1 million and $4 million for the three month ended March 31, 2016 and year ended December 31, 2015 , respectively. Included in compensation expense for 2016 was approximately $857,000 of expense for the accelerated vesting of stock options granted to retirement eligible colleagues. At March 31, 2016 , the Corporation had $8 million of unrecognized compensation expense related to stock options that is expected to be recognized over the remaining requisite service periods that extend predominantly through the fourth quarter 2019 . The following table summarizes information about the Corporation’s restricted stock activity for the year ended December 31, 2015 , and for the three months ended March 31, 2016 . Restricted Stock Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2014 1,982,126 $ 15.79 Granted 1,173,847 18.09 Vested (709,582 ) 15.62 Forfeited (196,363 ) 16.87 Outstanding at December 31, 2015 2,250,028 $ 17.03 Granted 1,041,985 16.37 Vested (732,553 ) 16.46 Forfeited (34,299 ) 17.69 Outstanding at March 31, 2016 2,525,161 $ 16.91 The Corporation amortizes the expense related to restricted stock awards as compensation expense over the vesting period specified in the grant. Performance-based restricted stock awards granted during 2015 and 2016 will vest ratably over a three year period, while service-based restricted stock awards granted during 2015 and 2016 will vest ratably over a four year period. Expense for restricted stock awards of approximately $7 million and $15 million was recorded for the three months ended March 31, 2016 and year ended December 31, 2015 , respectively. Included in compensation expense for 2016 was approximately $2 million of expense for the accelerated vesting of restricted stock awards granted to retirement eligible colleagues. The Corporation had $33 million of unrecognized compensation costs related to restricted stock awards at March 31, 2016 , that is expected to be recognized over the remaining requisite service periods that extend predominantly through fourth quarter 2019 . The Corporation has the ability to issue shares from treasury or new shares upon the exercise of stock options or the granting of restricted stock awards. The Board of Directors has authorized management to repurchase shares of the Corporation’s common stock each quarter in the market, to be made available for issuance in connection with the Corporation’s employee incentive plans and for other corporate purposes. The repurchase of shares will be based on market and investment opportunities, capital levels, growth prospects, and regulatory constraints. Such repurchases may occur from time to time in open market purchases, block transactions, private transactions, accelerated share repurchase programs, or similar facilities.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities Investment securities are generally classified as available for sale or held to maturity at the time of purchase. The majority of the Corporation's investment securities are mortgage-related securities issued by the Government National Mortgage Association (“GNMA”) or government-sponsored enterprises ("GSE") such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The amortized cost and fair values of securities available for sale and held to maturity were as follows. March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale: U. S. Treasury securities $ 1,000 $ — $ — $ 1,000 Residential mortgage-related securities: FNMA / FHLMC 1,268,929 35,321 (846 ) 1,303,404 GNMA 1,536,248 11,086 (79 ) 1,547,255 Private-label 1,535 — (23 ) 1,512 GNMA commercial mortgage-related securities 2,053,540 5,855 (11,530 ) 2,047,865 Other securities (debt and equity) 4,718 87 — 4,805 Total investment securities available for sale $ 4,865,970 $ 52,349 $ (12,478 ) $ 4,905,841 Investment securities held to maturity: Obligations of state and political subdivisions (municipal securities) $ 1,054,757 $ 25,972 $ (146 ) $ 1,080,583 Residential mortgage-related securities: FNMA / FHLMC 40,404 797 (180 ) 41,021 GNMA 81,660 1,086 (5 ) 82,741 Total investment securities held to maturity $ 1,176,821 $ 27,855 $ (331 ) $ 1,204,345 December 31, 2015 Amortized Gross Gross Fair Value ($ in Thousands) Investment securities available for sale: U. S. Treasury securities $ 999 $ — $ (2 ) $ 997 Residential mortgage-related securities: FNMA / FHLMC 1,388,995 33,791 (8,160 ) 1,414,626 GNMA 1,605,956 507 (16,460 ) 1,590,003 Private-label 1,722 1 (14 ) 1,709 GNMA commercial mortgage-related securities 1,982,477 1,334 (28,501 ) 1,955,310 Other securities (debt and equity) 4,718 51 — 4,769 Total investment securities available for sale $ 4,984,867 $ 35,684 $ (53,137 ) $ 4,967,414 Investment securities held to maturity: Municipal securities $ 1,043,767 $ 16,803 $ (339 ) $ 1,060,231 Residential mortgage-related securities: FNMA / FHLMC 41,469 513 (645 ) 41,337 GNMA 82,994 189 (309 ) 82,874 Total investment securities held to maturity $ 1,168,230 $ 17,505 $ (1,293 ) $ 1,184,442 The amortized cost and fair values of investment securities available for sale and held to maturity at March 31, 2016 , are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Available for Sale Held to Maturity ($ in Thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 2,500 $ 2,530 $ 46,749 $ 32,151 Due after one year through five years 3,200 3,200 243,423 255,338 Due after five years through ten years — — 245,683 255,755 Due after ten years — — 518,902 537,339 Total debt securities 5,700 5,730 1,054,757 1,080,583 Residential mortgage-related securities: FNMA / FHLMC 1,268,929 1,303,404 40,404 41,021 GNMA 1,536,248 1,547,255 81,660 82,741 Private-label 1,535 1,512 — — GNMA commercial mortgage-related securities 2,053,540 2,047,865 — — Equity securities 18 75 — — Total investment securities $ 4,865,970 $ 4,905,841 $ 1,176,821 $ 1,204,345 Ratio of Fair Value to Amortized Cost 100.8 % 102.3 % During the first three months of 2016, the Corporation continued to restructure its investment securities portfolio and sold approximately $119 million of FNMA and FHLMC mortgage-related securities and reinvested into GNMA mortgage-related securities, generating a $3 million net gain on sale. This restructuring lowered risk weighted assets and related capital requirements. Three Months Ended March 31, 2016 2015 ($ in Thousands) Gross gains $ 3,287 $ — Gross losses (189 ) — Investment securities gains, net $ 3,098 $ — Proceeds from sales of investment securities $ 119,379 $ 289 Pledged securities with a carrying value of approximately $2.7 billion and $3.2 billion at March 31, 2016 , and December 31, 2015 , respectively, were pledged to secure certain deposits or for other purposes as required or permitted by law. The following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position, at March 31, 2016 . Less than 12 months 12 months or more Total March 31, 2016 Number of Securities Unrealized Losses Fair Value Number of Securities Unrealized Losses Fair Value Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale: Residential mortgage-related securities: FNMA / FHLMC — $ — $ — 12 $ (846 ) $ 258,670 $ (846 ) $ 258,670 GNMA 2 (79 ) 41,913 — — — (79 ) 41,913 Private-label 1 (1 ) 76 3 (22 ) 1,382 (23 ) 1,458 GNMA commercial mortgage-related securities 20 (1,390 ) 558,620 21 (10,140 ) 448,861 (11,530 ) 1,007,481 Total 23 $ (1,470 ) $ 600,609 36 $ (11,008 ) $ 708,913 $ (12,478 ) $ 1,309,522 Investment securities held to maturity: Municipal securities 20 $ (75 ) $ 10,029 17 $ (71 ) $ 5,599 $ (146 ) $ 15,628 Residential mortgage-related securities: FNMA / FHLMC 1 (3 ) 1,180 5 (177 ) 13,587 (180 ) 14,767 GNMA — — — 1 (5 ) 1,548 (5 ) 1,548 Total 21 $ (78 ) $ 11,209 23 $ (253 ) $ 20,734 $ (331 ) $ 31,943 For comparative purposes, the following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2015 . Less than 12 months 12 months or more Total December 31, 2015 Number Unrealized Fair Number Unrealized Fair Unrealized Fair ($ in Thousands) Investment securities available for sale: U.S. Treasury securities 1 $ (2 ) $ 997 — $ — $ — $ (2 ) $ 997 Residential mortgage-related securities: FNMA / FHLMC 17 (1,548 ) 220,852 14 (6,612 ) 338,186 (8,160 ) 559,038 GNMA 46 (16,460 ) 1,434,484 — — — (16,460 ) 1,434,484 Private-label 1 (1 ) 83 3 (13 ) 1,565 (14 ) 1,648 GNMA commercial mortgage-related securities 40 (9,610 ) 1,132,844 21 (18,891 ) 448,218 (28,501 ) 1,581,062 Total 105 $ (27,621 ) $ 2,789,260 38 $ (25,516 ) $ 787,969 $ (53,137 ) $ 3,577,229 Investment securities held to maturity: Municipal securities 53 $ (146 ) $ 23,137 24 $ (193 ) $ 9,254 $ (339 ) $ 32,391 Residential mortgage-related securities: FNMA / FHLMC 10 (177 ) 12,754 3 (468 ) 11,106 (645 ) 23,860 GNMA 21 (201 ) 45,499 3 (108 ) 6,797 (309 ) 52,296 Total 84 $ (524 ) $ 81,390 30 $ (769 ) $ 27,157 $ (1,293 ) $ 108,547 The Corporation reviews the investment securities portfolio on a quarterly basis to monitor its exposure to other-than-temporary impairment. A determination as to whether a security’s decline in fair value is other-than-temporary takes into consideration numerous factors and the relative significance of any single factor can vary by security. Some factors the Corporation may consider in the other-than-temporary impairment analysis include, the length of time and extent to which the security has been in an unrealized loss position, changes in security ratings, financial condition and near-term prospects of the issuer, as well as security and industry specific economic conditions. Based on the Corporation’s evaluation, management does not believe any unrealized loss at March 31, 2016 , represents an other-than-temporary impairment as these unrealized losses are primarily attributable to changes in interest rates and the current market conditions, and not credit deterioration. The unrealized losses reported for municipal securities relate to various state and local political subdivisions and school districts. The Corporation currently does not intend to sell nor does it believe that it will be required to sell the securities contained in the above unrealized losses table before recovery of their amortized cost basis. The reduction in unrealized losses at March 31, 2016 is due to the reduction in overall interest rates. The U.S. Treasury 3-year and 5-year rates dropped by 44 basis points ("bp") and 55 bp, respectively, from December 31, 2015. Federal Home Loan Bank (“FHLB”) and Federal Reserve Bank Stocks: The Corporation is required to maintain Federal Reserve stock and FHLB stock as a member of both the Federal Reserve System and the FHLB, and in amounts as required by these institutions. These equity securities are “restricted” in that they can only be sold back to the respective institutions or another member institution at par. Therefore, they are less liquid than other marketable equity securities and their fair value is equal to amortized cost. At March 31, 2016 , and December 31, 2015 , the Corporation had FHLB stock of $108 million and $74 million , respectively, reflecting the overall increase in FHLB short-term and long-term funding. The Corporation had Federal Reserve Bank stock of $73 million at both March 31, 2016 and December 31, 2015 , respectively.

Loans

Loans	3 Months Ended
	Mar. 31, 2016
Receivables [Abstract]
Loans	Loans The period end loan composition was as follows. March 31, December 31, ($ in Thousands) Commercial and industrial $ 6,511,648 $ 6,190,683 Commercial real estate — owner occupied 917,285 918,212 Commercial and business lending 7,428,933 7,108,895 Commercial real estate — investor 3,276,733 3,234,266 Real estate construction 1,184,398 1,162,145 Commercial real estate lending 4,461,131 4,396,411 Total commercial 11,890,064 11,505,306 Residential mortgage 5,944,457 5,783,267 Home equity 982,994 1,005,802 Other consumer 409,725 419,968 Total consumer 7,337,176 7,209,037 Total loans $ 19,227,240 $ 18,714,343 The following table presents commercial and consumer loans by credit quality indicator at March 31, 2016 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 5,713,979 $ 272,090 $ 328,464 $ 197,115 $ 6,511,648 Commercial real estate - owner occupied 834,879 31,856 41,107 9,443 917,285 Commercial and business lending 6,548,858 303,946 369,571 206,558 7,428,933 Commercial real estate - investor 3,208,338 30,680 25,385 12,330 3,276,733 Real estate construction 1,180,914 222 2,422 840 1,184,398 Commercial real estate lending 4,389,252 30,902 27,807 13,170 4,461,131 Total commercial 10,938,110 334,848 397,378 219,728 11,890,064 Residential mortgage 5,883,743 5,014 3,488 52,212 5,944,457 Home equity 967,267 1,446 209 14,072 982,994 Other consumer 408,819 523 — 383 409,725 Total consumer 7,259,829 6,983 3,697 66,667 7,337,176 Total $ 18,197,939 $ 341,831 $ 401,075 $ 286,395 $ 19,227,240 The following table presents commercial and consumer loans by credit quality indicator at December 31, 2015 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 5,522,809 $ 341,169 $ 233,130 $ 93,575 $ 6,190,683 Commercial real estate - owner occupied 835,572 38,885 35,706 8,049 918,212 Commercial and business lending 6,358,381 380,054 268,836 101,624 7,108,895 Commercial real estate - investor 3,153,703 45,976 25,944 8,643 3,234,266 Real estate construction 1,157,034 252 3,919 940 1,162,145 Commercial real estate lending 4,310,737 46,228 29,863 9,583 4,396,411 Total commercial 10,669,118 426,282 298,699 111,207 11,505,306 Residential mortgage 5,727,437 1,552 2,796 51,482 5,783,267 Home equity 988,574 1,762 222 15,244 1,005,802 Other consumer 419,087 556 — 325 419,968 Total consumer 7,135,098 3,870 3,018 67,051 7,209,037 Total $ 17,804,216 $ 430,152 $ 301,717 $ 178,258 $ 18,714,343 Factors that are important to managing overall credit quality are sound loan underwriting and administration, systematic monitoring of existing loans and commitments, effective loan review on an ongoing basis, early identification of potential problems, and appropriate allowance for loan losses, allowance for unfunded commitments, nonaccrual, and charge off policies. For commercial loans, management has determined the pass credit quality indicator to include credits that exhibit acceptable financial statements, cash flow, and leverage. If any risk exists, it is mitigated by the loan structure, collateral, monitoring, or control. For consumer loans, performing loans include credits that are performing in accordance with the original contractual terms. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Special mention credits have potential weaknesses that deserve management’s attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the credit. Potential problem loans are considered inadequately protected by the current net worth and paying capacity of the obligor or the collateral pledged. These loans generally have a well-defined weakness, or weaknesses, that may jeopardize liquidation of the debt and are characterized by the distinct possibility that the Corporation will sustain some loss if the deficiencies are not corrected. Lastly, management considers a loan to be impaired when it is probable that the Corporation will be unable to collect all amounts due according to the original contractual terms of the note agreement, including both principal and interest. Management has determined that commercial and consumer loan relationships that have nonaccrual status or have had their terms restructured in a troubled debt restructuring meet this impaired loan definition. Commercial loans classified as special mention, potential problem, and nonaccrual loans are reviewed at a minimum on a quarterly basis, while pass and performing rated credits are reviewed on an annual basis or more frequently if the loan renewal is less than one year or if otherwise warranted. The following table presents loans by past due status at March 31, 2016 . Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due (a) Nonaccrual (b) Total ($ in Thousands) Commercial and industrial $ 6,311,415 $ 2,665 $ 236 $ 217 $ 197,115 $ 6,511,648 Commercial real estate - owner occupied 907,322 520 — — 9,443 917,285 Commercial and business lending 7,218,737 3,185 236 217 206,558 7,428,933 Commercial real estate - investor 3,263,331 748 324 — 12,330 3,276,733 Real estate construction 1,183,143 415 — — 840 1,184,398 Commercial real estate lending 4,446,474 1,163 324 — 13,170 4,461,131 Total commercial 11,665,211 4,348 560 217 219,728 11,890,064 Residential mortgage 5,888,651 3,199 395 — 52,212 5,944,457 Home equity 963,118 4,410 1,394 — 14,072 982,994 Other consumer 406,248 1,020 662 1,412 383 409,725 Total consumer 7,258,017 8,629 2,451 1,412 66,667 7,337,176 Total $ 18,923,228 $ 12,977 $ 3,011 $ 1,629 $ 286,395 $ 19,227,240 (a) The recorded investment in loans past due 90 days or more and still accruing totaled $2 million at March 31, 2016 (the same as the reported balances for the accruing loans noted above). (b) Of the total nonaccrual loans, $230 million or 80% were current with respect to payment at March 31, 2016 . The following table presents loans by past due status at December 31, 2015 . Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due (a) Nonaccrual (b) Total ($ in Thousands) Commercial and industrial $ 6,095,848 $ 602 $ 409 $ 249 $ 93,575 $ 6,190,683 Commercial real estate - owner occupied 903,021 7,142 — — 8,049 918,212 Commercial and business lending 6,998,869 7,744 409 249 101,624 7,108,895 Commercial real estate - investor 3,225,332 291 — — 8,643 3,234,266 Real estate construction 1,160,909 270 26 — 940 1,162,145 Commercial real estate lending 4,386,241 561 26 — 9,583 4,396,411 Total commercial 11,385,110 8,305 435 249 111,207 11,505,306 Residential mortgage 5,726,855 4,491 439 — 51,482 5,783,267 Home equity 982,639 6,190 1,729 — 15,244 1,005,802 Other consumer 416,374 1,195 675 1,399 325 419,968 Total consumer 7,125,868 11,876 2,843 1,399 67,051 7,209,037 Total $ 18,510,978 $ 20,181 $ 3,278 $ 1,648 $ 178,258 $ 18,714,343 (a) The recorded investment in loans past due 90 days or more and still accruing totaled $2 million at December 31, 2015 (the same as the reported balances for the accruing loans noted above). (b) Of the total nonaccrual loans, $124 million or 69% were current with respect to payment at December 31, 2015 . The following table presents impaired loans at March 31, 2016 . Recorded Unpaid Related Average Interest ($ in Thousands) Loans with a related allowance Commercial and industrial $ 105,780 $ 106,837 $ 14,595 $ 106,280 $ 613 Commercial real estate — owner occupied 10,477 10,596 554 10,552 89 Commercial and business lending 116,257 117,433 15,149 116,832 702 Commercial real estate — investor 23,494 24,430 1,244 23,541 461 Real estate construction 1,226 1,812 412 1,237 14 Commercial real estate lending 24,720 26,242 1,656 24,778 475 Total commercial 140,977 143,675 16,805 141,610 1,177 Residential mortgage 65,281 70,624 12,351 65,819 548 Home equity 20,337 22,451 9,732 20,504 248 Other consumer 1,276 1,332 221 1,291 8 Total consumer 86,894 94,407 22,304 87,614 804 Total loans (a) $ 227,871 $ 238,082 $ 39,109 $ 229,224 $ 1,981 Loans with no related allowance Commercial and industrial $ 120,243 $ 130,935 $ — $ 120,399 $ 91 Commercial real estate — owner occupied 6,659 9,005 — 6,715 — Commercial and business lending 126,902 139,940 — 127,114 91 Commercial real estate — investor 9,829 9,984 — 9,855 — Real estate construction — — — — — Commercial real estate lending 9,829 9,984 — 9,855 — Total commercial 136,731 149,924 — 136,969 91 Residential mortgage 6,738 7,020 — 6,841 35 Home equity 652 652 — 653 10 Other consumer — — — — — Total consumer 7,390 7,672 — 7,494 45 Total loans (a) $ 144,121 $ 157,596 $ — $ 144,463 $ 136 Total Commercial and industrial $ 226,023 $ 237,772 $ 14,595 $ 226,679 $ 704 Commercial real estate — owner occupied 17,136 19,601 554 17,267 89 Commercial and business lending 243,159 257,373 15,149 243,946 793 Commercial real estate — investor 33,323 34,414 1,244 33,396 461 Real estate construction 1,226 1,812 412 1,237 14 Commercial real estate lending 34,549 36,226 1,656 34,633 475 Total commercial 277,708 293,599 16,805 278,579 1,268 Residential mortgage 72,019 77,644 12,351 72,660 583 Home equity 20,989 23,103 9,732 21,157 258 Other consumer 1,276 1,332 221 1,291 8 Total consumer 94,284 102,079 22,304 95,108 849 Total loans (a) $ 371,992 $ 395,678 $ 39,109 $ 373,687 $ 2,117 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 84% of the unpaid principal balance at March 31, 2016 . The following table presents impaired loans at December 31, 2015 . Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized ($ in Thousands) Loans with a related allowance Commercial and industrial $ 57,785 $ 59,409 $ 8,162 $ 46,833 $ 855 Commercial real estate — owner occupied 9,705 9,804 448 10,087 412 Commercial and business lending 67,490 69,213 8,610 56,920 1,267 Commercial real estate — investor 27,822 29,444 1,831 28,278 1,914 Real estate construction 1,450 2,154 453 1,667 66 Commercial real estate lending 29,272 31,598 2,284 29,945 1,980 Total commercial 96,762 100,811 10,894 86,865 3,247 Residential mortgage 66,590 71,084 12,462 68,183 2,374 Home equity 21,769 23,989 10,118 22,624 1,147 Other consumer 1,154 1,225 195 1,199 30 Total consumer 89,513 96,298 22,775 92,006 3,551 Total loans (a) $ 186,275 $ 197,109 $ 33,669 $ 178,871 $ 6,798 Loans with no related allowance Commercial and industrial $ 65,083 $ 72,259 $ — $ 79,573 $ 1,657 Commercial real estate — owner occupied 6,221 6,648 — 6,534 15 Commercial and business lending 71,304 78,907 — 86,107 1,672 Commercial real estate — investor 2,736 2,840 — 2,763 90 Real estate construction — — — — — Commercial real estate lending 2,736 2,840 — 2,763 90 Total commercial 74,040 81,747 — 88,870 1,762 Residential mortgage 4,762 5,033 — 4,726 126 Home equity 544 544 — 544 30 Other consumer — — — — — Total consumer 5,306 5,577 — 5,270 156 Total loans (a) $ 79,346 $ 87,324 $ — $ 94,140 $ 1,918 Total Commercial and industrial $ 122,868 $ 131,668 $ 8,162 $ 126,406 $ 2,512 Commercial real estate — owner occupied 15,926 16,452 448 16,621 427 Commercial and business lending 138,794 148,120 8,610 143,027 2,939 Commercial real estate — investor 30,558 32,284 1,831 31,041 2,004 Real estate construction 1,450 2,154 453 1,667 66 Commercial real estate lending 32,008 34,438 2,284 32,708 2,070 Total commercial 170,802 182,558 10,894 175,735 5,009 Residential mortgage 71,352 76,117 12,462 72,909 2,500 Home equity 22,313 24,533 10,118 23,168 1,177 Other consumer 1,154 1,225 195 1,199 30 Total consumer 94,819 101,875 22,775 97,276 3,707 Total loans (a) $ 265,621 $ 284,433 $ 33,669 $ 273,011 $ 8,716 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 82% of the unpaid principal balance at December 31, 2015 . Troubled Debt Restructurings (“Restructured Loans”): Loans are considered restructured loans if concessions have been granted to borrowers that are experiencing financial difficulty. See Note 1 “Summary of Significant Accounting Policies," in the Corporation’s 2015 Annual Report on Form 10-K for the Corporation's accounting policy for troubled debt restructurings. The Corporation had a recorded investment of over $4 million in loans modified in troubled debt restructurings for the three months ended March 31, 2016 , of which approximately $470,000 was in accrual status and $4 million was in nonaccrual pending a sustained period of repayment. The following table presents nonaccrual and performing restructured loans by loan portfolio. March 31, 2016 December 31, 2015 Performing Restructured Loans Nonaccrual Restructured Loans (a) Performing Restructured Loans Nonaccrual Restructured Loans (a) ($ in Thousands) Commercial and industrial $ 28,908 $ 2,711 $ 29,293 $ 1,714 Commercial real estate — owner occupied 7,693 2,689 7,877 2,703 Commercial real estate — investor 20,993 1,356 21,915 3,936 Real estate construction 386 182 510 177 Residential mortgage 19,807 23,845 19,870 24,592 Home equity 6,917 4,416 7,069 4,522 Other consumer 893 33 829 40 Total $ 85,597 $ 35,232 $ 87,363 $ 37,684 (a) Nonaccrual restructured loans have been included within nonaccrual loans. The following table provides the number of loans modified in a troubled debt restructuring by loan portfolio during the three months ended March 31, 2016 and 2015 , respectively, and the recorded investment and unpaid principal balance as of March 31, 2016 and 2015 respectively. Three Months Ended March 31, 2016 Three Months Ended March 31, 2015 Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) ($ in Thousands) Commercial and industrial 7 $ 1,483 $ 1,522 2 $ 196 $ 208 Commercial real estate — owner occupied 1 125 130 5 3,585 3,641 Commercial real estate — investor — — — 4 3,030 3,042 Real estate construction 1 10 55 — — — Residential mortgage 30 2,062 2,124 30 2,816 2,864 Home equity 20 818 879 36 1,782 1,843 Total 59 $ 4,498 $ 4,710 77 $ 11,409 $ 11,598 (a) Represents post-modification outstanding recorded investment. (b) Represents pre-modification outstanding recorded investment. Restructured loan modifications may include payment schedule modifications, interest rate concessions, maturity date extensions, modification of note structure (A/B Note), non-reaffirmed Chapter 7 bankruptcies, principal reduction, or some combination of these concessions. During the three months ended March 31, 2016 , restructured loan modifications of commercial and industrial, commercial real estate, and real estate construction loans primarily included maturity date extensions and payment schedule modifications. Restructured loan modifications of home equity and residential mortgage loans primarily included maturity date extensions, interest rate concessions, non-reaffirmed Chapter 7 bankruptcies, or a combination of these concessions for the three months ended March 31, 2016 . The following table provides the number of loans modified in a troubled debt restructuring during the previous twelve months which subsequently defaulted during the three months ended March 31, 2016 and 2015 , respectively, as well as the recorded investment in these restructured loans as of March 31, 2016 and 2015 respectively. Three Months Ended March 31, 2016 Three Month Ended March 31, 2015 Number of Loans Recorded Investment Number of Loans Recorded Investment ($ in Thousands) Commercial real estate — owner occupied — $ — 1 $ 297 Real estate construction 1 10 — — Residential mortgage 7 1,151 16 1,239 Home equity 8 153 24 855 Total 16 $ 1,314 41 $ 2,391 All loans modified in a troubled debt restructuring are evaluated for impairment. The nature and extent of the impairment of restructured loans, including those which have experienced a subsequent payment default, is considered in the determination of an appropriate level of the allowance for loan losses. A summary of the changes in the allowance for loan losses by portfolio segment for the three months ended March 31, 2016 , was as follows. $ in Thousands Commercial and industrial Commercial real estate - owner occupied Commercial real estate - investor Real estate construction Residential mortgage Home equity Other consumer Total December 31, 2015 $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Charge offs (16,894 ) (76 ) (176 ) (54 ) (1,390 ) (1,746 ) (909 ) (21,245 ) Recoveries 1,958 33 1,415 26 158 600 161 4,351 Net charge offs (14,936 ) (43 ) 1,239 (28 ) (1,232 ) (1,146 ) (748 ) (16,894 ) Provision for loan losses 24,470 (2,059 ) (2,233 ) (3,498 ) 2,030 721 569 20,000 March 31, 2016 $ 139,493 $ 16,578 $ 42,024 $ 21,740 $ 29,059 $ 23,130 $ 5,346 $ 277,370 Allowance for loan losses: Individually evaluated for impairment $ 14,005 $ 74 $ — $ — $ 14 $ — $ — $ 14,093 Collectively evaluated for impairment 125,488 16,504 42,024 21,740 29,045 23,130 5,346 263,277 Total allowance for loan losses $ 139,493 $ 16,578 $ 42,024 $ 21,740 $ 29,059 $ 23,130 $ 5,346 $ 277,370 Loans: Individually evaluated for impairment $ 195,341 $ 7,500 $ 9,829 $ — $ 7,472 $ 652 $ — $ 220,794 Collectively evaluated for impairment 6,316,307 909,785 3,266,904 1,184,398 5,936,985 982,342 409,725 19,006,446 Total loans $ 6,511,648 $ 917,285 $ 3,276,733 $ 1,184,398 $ 5,944,457 $ 982,994 $ 409,725 $ 19,227,240 The allowance for credit losses is comprised of the allowance for loan losses and the allowance for unfunded commitments. The level of the allowance for loan losses represents management’s estimate of an amount appropriate to provide for probable credit losses in the loan portfolio at the balance sheet date. The allowance for unfunded commitments is maintained at a level believed by management to be sufficient to absorb estimated probable losses related to unfunded credit facilities (including unfunded loan commitments and letters of credit) and is included in accrued expenses and other liabilities on the consolidated balance sheets. See Note 12 for additional information on the allowance for unfunded commitments. For comparison purposes, a summary of the changes in the allowance for loan losses by portfolio segment for the year ended December 31, 2015 , was as follows. $ in Thousands Commercial and industrial Commercial real estate - owner occupied Commercial real estate - investor Real estate construction Residential mortgage Home equity Other consumer Total December 31, 2014 $ 117,635 $ 16,510 $ 46,333 $ 20,999 $ 31,926 $ 26,464 $ 6,435 $ 266,302 Charge offs (27,687 ) (2,645 ) (4,645 ) (750 ) (5,636 ) (7,048 ) (3,869 ) (52,280 ) Recoveries 9,821 921 4,157 2,268 1,077 3,233 765 22,242 Net charge offs (17,866 ) (1,724 ) (488 ) 1,518 (4,559 ) (3,815 ) (3,104 ) (30,038 ) Provision for loan losses 30,190 3,894 (2,827 ) 2,749 894 906 2,194 38,000 December 31, 2015 $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Allowance for loan losses: Individually evaluated for impairment $ 7,522 $ — $ 229 $ — $ 166 $ 46 $ — $ 7,963 Collectively evaluated for impairment 122,437 18,680 42,789 25,266 28,095 23,509 5,525 266,301 Total allowance for loan losses $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Loans: Individually evaluated for impairment $ 91,569 $ 6,221 $ 5,460 $ — $ 6,956 $ 1,281 $ — $ 111,487 Collectively evaluated for impairment 6,099,114 911,991 3,228,806 1,162,145 5,776,311 1,004,521 419,968 18,602,856 Total loans $ 6,190,683 $ 918,212 $ 3,234,266 $ 1,162,145 $ 5,783,267 $ 1,005,802 $ 419,968 $ 18,714,343 A summary of the changes in the allowance for unfunded commitments was as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Allowance for Unfunded Commitments: Balance at beginning of period $ 24,400 $ 24,900 Provision for unfunded commitments — (500 ) Balance at end of period $ 24,400 $ 24,400

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Other Intangible Assets Goodwill: Goodwill is not amortized but, instead, is subject to impairment tests on at least an annual basis, and more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The impairment testing process is conducted by assigning net assets and goodwill to each reporting unit. An initial qualitative evaluation is made to assess the likelihood of impairment and determine whether further quantitative testing to calculate the fair value is necessary. When the qualitative evaluation indicates that impairment is more likely than not, quantitative testing is required whereby the fair value of each reporting unit is calculated and compared to the recorded book value, “step one.” If the calculated fair value of the reporting unit exceeds its carrying value, goodwill is not considered impaired and “step two” is not considered necessary. If the carrying value of a reporting unit exceeds its calculated fair value, the impairment test continues (“step two”) by comparing the carrying value of the reporting unit’s goodwill to the implied fair value of goodwill. The implied fair value is computed by adjusting all assets and liabilities of the reporting unit to current fair value with the offset adjustment to goodwill. The adjusted goodwill balance is the implied fair value of the goodwill. An impairment charge is recognized if the carrying value of goodwill exceeds the implied fair value of goodwill. The Corporation conducted its most recent annual impairment testing in May 2015, utilizing a qualitative assessment. Factors that management considered in this assessment included macroeconomic conditions, industry and market considerations, overall financial performance of the Corporation and each reporting unit (both current and projected), changes in management strategy, and changes in the composition or carrying amount of net assets. In addition, management considered the changes in both the Corporation’s common stock price and in the overall bank common stock index (based on the S&P 400 Regional Bank Sub-Industry Index), as well as the Corporation’s earnings per common share trend over the past year. Based on these assessments, management concluded that the 2015 annual qualitative impairment assessment indicated that it is more likely than not that the estimated fair value exceeded the carrying value (including goodwill) for each reporting unit. Therefore, a step one quantitative analysis was not required. There were no events since the May 2015 impairment testing that have changed the Corporation's impairment assessment conclusion. There were no impairment charges recorded in 2015 or the first three months of 2016. At March 31, 2016 , the Corporation had goodwill of $972 million , compared to $969 million at December 31, 2015 . Goodwill increased by approximately $3 million during the first quarter of 2016 as a result of two small insurance acquisitions. See Note 2 for additional information on the Corporation's acquisitions. Other Intangible Assets: The Corporation has other intangible assets that are amortized, consisting of core deposit intangibles, other intangibles (primarily related to customer relationships acquired in connection with the Corporation’s insurance agency acquisitions), and mortgage servicing rights. Core deposit intangibles of approximately $15 million were fully amortized in 2015 and have been removed from both the gross carrying amount and the accumulated amortization for 2016. Other intangibles increased by approximately $1 million during the first quarter of 2016 for the customer relationships associated with two small insurance acquisitions. See Note 2 for additional information on the Corporation's acquisitions. For core deposit intangibles and other intangibles, changes in the gross carrying amount, accumulated amortization, and net book value were as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Core deposit intangibles: Gross carrying amount $ 4,385 $ 19,545 Accumulated amortization (4,062 ) (19,152 ) Net book value $ 323 $ 393 Amortization during the year $ 70 $ 1,404 Other intangibles: Gross carrying amount $ 32,410 $ 31,398 Accumulated amortization (15,767 ) (15,333 ) Net book value $ 16,643 $ 16,065 Additions during the period $ 1,012 $ 12,115 Amortization during the year $ 434 $ 1,690 The Corporation sells residential mortgage loans in the secondary market and typically retains the right to service the loans sold. Mortgage servicing rights are amortized in proportion to and over the period of estimated net servicing income, and assessed for impairment at each reporting date. The Corporation periodically evaluates its mortgage servicing rights asset for impairment. Impairment is assessed based on fair value at each reporting date using estimated prepayment speeds of the underlying mortgage loans serviced and stratifications based on the risk characteristics of the underlying loans (predominantly loan type and note interest rate). As mortgage interest rates fall, prepayment speeds are usually faster and the value of the mortgage servicing rights asset generally decreases, requiring additional valuation reserve. Conversely, as mortgage interest rates rise, prepayment speeds are usually slower and the value of the mortgage servicing rights asset generally increases, requiring less valuation reserve. A valuation allowance is established, through a charge to earnings, to the extent the amortized cost of the mortgage servicing rights exceeds the estimated fair value by stratification. If it is later determined that all or a portion of the temporary impairment no longer exists for a stratification, the valuation is reduced through a recovery to earnings. An other-than-temporary impairment (i.e., recoverability is considered remote when considering interest rates and loan pay off activity) is recognized as a write-down of the mortgage servicing rights asset and the related valuation allowance (to the extent a valuation allowance is available) and then against earnings. A direct write-down permanently reduces the carrying value of the mortgage servicing rights asset and valuation allowance, precluding subsequent recoveries. See Note 12 for a discussion of the recourse provisions on sold residential mortgage loans. See Note 13 which further discusses fair value measurement relative to the mortgage servicing rights asset. A summary of changes in the balance of the mortgage servicing rights asset and the mortgage servicing rights valuation allowance was as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Mortgage servicing rights Mortgage servicing rights at beginning of period $ 62,150 $ 61,379 Additions 1,856 12,372 Amortization (2,874 ) (11,601 ) Mortgage servicing rights at end of period $ 61,132 $ 62,150 Valuation allowance at beginning of period (809 ) (1,234 ) (Additions) recoveries, net (909 ) 425 Valuation allowance at end of period (1,718 ) (809 ) Mortgage servicing rights, net $ 59,414 $ 61,341 Fair value of mortgage servicing rights $ 61,410 $ 70,686 Portfolio of residential mortgage loans serviced for others (“servicing portfolio”) $ 7,876,888 $ 7,915,224 Mortgage servicing rights, net to servicing portfolio 0.75 % 0.77 % Mortgage servicing rights expense (1) $ 3,783 $ 11,176 (1) Includes the amortization of mortgage servicing rights and additions / recoveries to the valuation allowance of mortgage servicing rights, and is a component of mortgage banking, net in the consolidated statements of income. The following table shows the estimated future amortization expense for amortizing intangible assets. The projections of amortization expense are based on existing asset balances, the current interest rate environment, and prepayment speeds as of March 31, 2016 . The actual amortization expense the Corporation recognizes in any given period may be significantly different depending upon acquisition or sale activities, changes in interest rates, prepayment speeds, market conditions, regulatory requirements, and events or circumstances that indicate the carrying amount of an asset may not be recoverable. Estimated Amortization Expense Core Deposit Intangibles Other Intangibles Mortgage Servicing Rights ($ in Thousands) Nine months ending December 31, 2016 $ 211 $ 1,378 $ 8,850 2017 112 1,786 9,674 2018 — 1,756 7,761 2019 — 1,457 6,313 2020 — 1,340 5,169 2021 — 1,316 4,265 Beyond 2021 — 7,610 19,100 Total Estimated Amortization Expense $ 323 $ 16,643 $ 61,132

Short and Long-Term Funding

Short and Long-Term Funding	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Short and Long-Term Funding	Short and Long-Term Funding The components of short-term funding (funding with original contractual maturities of one year or less) and long-term funding (funding with original contractual maturities greater than one year) were as follows. March 31, 2016 December 31, 2015 ($ in Thousands) Short-Term Funding Federal funds purchased $ 74,985 $ 47,870 Securities sold under agreements to repurchase 508,262 383,568 Federal funds purchased and securities sold under agreements to repurchase $ 583,247 $ 431,438 FHLB advances 770,000 335,000 Commercial paper 64,161 67,978 Other short-term funding 834,161 402,978 Total short-term funding $ 1,417,408 $ 834,416 Long-Term Funding FHLB advances $ 2,365,216 $ 1,750,225 Senior notes, at par 250,000 680,000 Subordinated notes, at par 250,000 250,000 Other long-term funding and capitalized costs (1) (3,900 ) (4,061 ) Total long-term funding 2,861,316 2,676,164 Total short and long-term funding $ 4,278,724 $ 3,510,580 (1) Debt issuance costs are now reflected on the balance sheet with the related debt issued rather than within other assets. See Note 3 for additional information on this new accounting standard. Securities sold under agreements to repurchase ("repurchase agreements") The Corporation enters into agreements under which it sells securities subject to an obligation to repurchase the same or similar securities. Under these arrangements, the Corporation may transfer legal control over the assets but still retain effective control through an agreement that both entitles and obligates the Corporation to repurchase the assets. The obligation to repurchase the securities is reflected as a liability on the Corporation’s consolidated balance sheets, while the securities underlying the repurchase agreements remain in the respective investment securities asset accounts (i.e., there is no offsetting or netting of the investment securities assets with the repurchase agreement liabilities). See Note 11 for additional disclosures on balance sheet offsetting. The Corporation utilizes securities sold under agreements to repurchase to facilitate the needs of its customers. As of March 31, 2016, the Corporation pledged GSE mortgage-related securities with a fair value of $643 million as collateral for the repurchase agreements. Securities pledged as collateral under repurchase agreements are maintained with the Corporation's safekeeping agents and are monitored on a daily basis due to the market risk of fair value changes in the underlying securities. The Corporation generally pledges excess securities to ensure there is sufficient collateral to satisfy short-term fluctuations in both the repurchase agreement balances and the fair value of the underlying securities. The remaining contractual maturity of the securities sold under agreements to repurchase in the consolidated balance sheets as of March 31, 2016 and December 31, 2015 are presented in the following table. Remaining Contractual Maturity of the Agreements March 31, 2016 Overnight and Continuous Up to 30 days 30-90 days Greater than 90 days Total ($ in Thousands) Repurchase agreements GSE securities $ 508,262 $ — $ — $ — $ 508,262 Total $ 508,262 $ — $ — $ — $ 508,262 December 31, 2015 Repurchase agreements GSE securities $ 383,568 $ — $ — $ — $ 383,568 Total $ 383,568 $ — $ — $ — $ 383,568 Long-term funding: FHLB advances: At March 31, 2016, the long-term FHLB advances had a weighted average interest rate of 0.29% , compared to 0.24% at December 31, 2015 . The FHLB advances are indexed to the FHLB discount note and re-price at varying intervals. The advances offer flexible, low cost, long-term funding that improves the Corporation’s liquidity profile. 2011 Senior Notes: In March 2011, the Corporation issued $300 million of senior notes due March 2016, and callable February 2016, with a 5.125% fixed coupon at a discount. In September 2011, the Corporation “re-opened” the offering and issued an additional $130 million of the same notes at a premium. All notes were redeemed in February 2016 at par. 2014 Senior Notes: In November 2014, the Corporation issued $250 million of senior notes, due November 2019, and callable October 2019. The senior notes have a fixed coupon interest rate of 2.75% and were issued at a discount. 2014 Subordinated Notes: In November 2014, the Corporation issued $250 million of 10 -year subordinated notes, due January 2025, and callable October 2024. The subordinated notes have a fixed coupon interest rate of 4.25% and were issued at a discount.

Derivative and Hedging Activiti

Derivative and Hedging Activities	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative and Hedging Activities	Derivative and Hedging Activities The Corporation facilitates customer borrowing activity by providing various interest rate risk management, commodity hedging, and foreign currency exchange solutions through its capital markets area. To date, all of the notional amounts of customer transactions have been matched with a mirror hedge with another counterparty. The Corporation has used, and may use again in the future, derivative instruments to hedge the variability in interest payments or protect the value of certain assets and liabilities recorded on its consolidated balance sheets from changes in interest rates. The predominant derivative and hedging activities include interest rate-related instruments (swaps and caps), foreign currency exchange forwards, commodity contracts, written options, purchased options, and certain mortgage banking activities. The contract or notional amount of a derivative is used to determine, along with the other terms of the derivative, the amounts to be exchanged between the counterparties. The Corporation is exposed to credit risk in the event of nonperformance by counterparties to financial instruments. To mitigate the counterparty risk, interest rate and commodity-related instruments generally contain language outlining collateral pledging requirements for each counterparty. Collateral must be posted when the market value exceeds certain mutually agreed upon threshold limits. The Corporation was required to pledge $28 million of investment securities as collateral at March 31, 2016 , and pledged $9 million of investment securities as collateral at December 31, 2015 . Federal regulations require the Corporation to clear all LIBOR interest rate swaps through a clearing house if it can be cleared. As such, the Corporation is required to pledge cash collateral for the margin. At March 31, 2016 , the Corporation posted cash collateral for the margin of $31 million , compared to $22 million at December 31, 2015 . The Corporation’s derivative and hedging instruments are recorded at fair value on the consolidated balance sheets. The fair value of the Corporation’s interest rate-related instruments is determined using discounted cash flow analysis on the expected cash flows of each derivative and also includes a nonperformance / credit risk component (credit valuation adjustment). See Note 13 for additional fair value information and disclosures. The table below identifies the balance sheet category and fair values of the Corporation’s free standing derivative instruments, which are not designated as hedging instruments. March 31, 2016 December 31, 2015 ($ in Thousands) Notional Amount Fair Value Balance Sheet Category Notional Amount Fair Balance Sheet Interest rate-related instruments — customer and mirror $ 1,806,688 $ 47,780 Trading assets $ 1,665,965 $ 29,391 Trading assets Interest rate-related instruments — customer and mirror 1,806,688 (50,145 ) Trading liabilities 1,665,965 (30,886 ) Trading liabilities Interest rate lock commitments (mortgage) 418,136 2,689 Other assets 271,530 958 Other assets Forward commitments (mortgage) 249,866 (1,732 ) Other liabilities 231,798 403 Other assets Foreign currency exchange forwards 124,617 4,203 Trading assets 72,976 1,532 Trading assets Foreign currency exchange forwards 116,751 (4,097 ) Trading liabilities 65,649 (1,398 ) Trading liabilities Commodity contracts 43,646 1,104 Trading assets 44,380 1,269 Trading assets Commodity contracts 43,770 (981 ) Trading liabilities 44,256 (1,146 ) Trading liabilities Purchased options (time deposit) 103,475 2,228 Other assets 104,582 2,715 Other assets Written options (time deposit) 103,475 (2,228 ) Other liabilities 104,582 (2,715 ) Other liabilities The table below identifies the income statement category of the gains and losses recognized in income on the Corporation’s derivative instruments not designated as hedging instruments. Income Statement Category of Gain / (Loss) Recognized in Income For the Three Months Ended March 31, ($ in Thousands) 2016 2015 Derivative Instruments: Interest rate-related instruments — customer and mirror, net Capital market fees, net $ (870 ) $ (294 ) Interest rate lock commitments (mortgage) Mortgage banking, net 1,731 1,738 Forward commitments (mortgage) Mortgage banking, net (2,135 ) 640 Foreign currency exchange forwards Capital market fees, net (28 ) 66 Commodity contracts Capital market fees, net — — Free Standing Derivatives The Corporation enters into various derivative contracts which are designated as free standing derivative contracts. Free standing derivative products are entered into primarily for the benefit of commercial customers seeking to manage their exposures to interest rate risk, foreign currency, and commodity prices. These derivative contracts are not designated against specific assets and liabilities on the balance sheet or forecasted transactions and, therefore, do not qualify for hedge accounting treatment. Such derivative contracts are carried at fair value on the consolidated balance sheets with changes in the fair value recorded as a component of Capital market fees, net, and typically include interest rate-related instruments (swaps and caps), foreign currency exchange forwards, and commodity contracts. See Note 11 for additional information and disclosures on balance sheet offsetting. Interest rate-related instruments: The Corporation provides interest rate risk management services to commercial customers, primarily forward interest rate swaps and caps. The Corporation’s market risk from unfavorable movements in interest rates related to these derivative contracts is generally economically hedged by concurrently entering into offsetting derivative contracts. The offsetting derivative contracts have identical notional values, terms and indices. Foreign currency exchange forwards: The Corporation provides foreign currency exchange services to customers, primarily forward contracts. Our customers enter into a foreign currency exchange forward with the Corporation as a means for them to mitigate exchange rate risk. The Corporation mitigates its risk by then entering into an offsetting foreign currency exchange derivative contract. Such foreign currency exchange contracts are carried at fair value on the consolidated balance sheets with changes in fair value recorded as a component of Capital market fees, net. Commodity contracts: Commodity contracts are entered into primarily for the benefit of commercial customers seeking to manage their exposure to fluctuating commodity prices. The Corporation mitigates its risk by then entering into an offsetting commodity derivative contract. Commodity contracts are carried at fair value on the consolidated balance sheets with changes in fair value recorded as a component of Capital market fees, net. Mortgage derivatives Interest rate lock commitments to originate residential mortgage loans held for sale and forward commitments to sell residential mortgage loans are considered derivative instruments, and the fair value of these commitments is recorded on the consolidated balance sheets with the changes in fair value recorded as a component of mortgage banking, net. Written and purchased options (time deposit) Historically, the Corporation had entered into written and purchased option derivative instruments to facilitate an equity linked time deposit product (the “Power CD”), which the Corporation ceased offering in September 2013. The Power CD was a time deposit that provided the purchaser a guaranteed return of principal at maturity plus a potential equity return (a written option), while the Corporation received a known stream of funds based on the equity return (a purchased option). The written and purchased options are mirror derivative instruments which are carried at fair value on the consolidated balance sheets.

Balance Sheet Offsetting

Balance Sheet Offsetting	3 Months Ended
	Mar. 31, 2016
Offsetting [Abstract]
Balance Sheet Offsetting	Balance Sheet Offsetting Interest Rate-Related Instruments and Commodity Contracts (“Interest and Commodity Agreements”) The Corporation enters into interest rate-related instruments to facilitate the interest rate risk management strategies of commercial customers. The Corporation also enters into commodity contracts to manage commercial customers' exposure to fluctuating commodity prices. The Corporation mitigates these risks by entering into equal and offsetting interest and commodity agreements with highly rated third party financial institutions. The Corporation is party to master netting arrangements with its financial institution counterparties that creates a single net settlement of all legal claims or obligations to pay or receive the net amount of settlement of the individual interest and commodity agreements. Collateral, usually in the form of investment securities and cash, is posted by the counterparty with net liability positions in accordance with contract thresholds. The Corporation does not offset assets and liabilities under these arrangements for financial statement presentation purposes. See Note 10 for additional information on the Corporation’s derivative and hedging activities. Securities Sold Under Agreements to Repurchase (“Repurchase Agreements”) The Corporation enters into agreements under which it sells securities subject to an obligation to repurchase the same or similar securities. These repurchase agreements are accounted for as collateralized financing arrangements (i.e., secured borrowings) and not as a sale and subsequent repurchase of securities (i.e., there is no offsetting or netting of the investment securities assets with the repurchase agreement liabilities). The right of set-off for a repurchase agreement resembles a secured borrowing, whereby the collateral would be used to settle the fair value of the repurchase agreement should the Corporation be in default (e.g., fails to make an interest payment to the counterparty). In addition, the Corporation does not enter into reverse repurchase agreements; therefore, there is no such offsetting to be done with the repurchase agreements. See Note 9 for additional disclosures on repurchase agreements. The following table presents the assets and liabilities subject to an enforceable master netting arrangement. The interest and commodity agreements we have with our commercial customers are not subject to an enforceable master netting arrangement, and therefore, are excluded from this table. Gross amounts recognized Gross amounts not offset in the balance sheet Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Collateral Net amount ($ in Thousands) March 31, 2016 Derivative assets: Interest and commodity agreements $ 823 $ — $ 823 $ (823 ) $ — $ — Derivative liabilities: Interest and commodity agreements $ 48,700 $ — $ 48,700 $ (823 ) $ (47,877 ) $ — December 31, 2015 Derivative assets: Interest and commodity instruments $ 1,466 $ — $ 1,466 $ (1,466 ) $ — $ — Derivative liabilities: Interest and commodity instruments $ 30,200 $ — $ 30,200 $ (1,466 ) $ (28,734 ) $ —

Commitments, Off-Balance Sheet

Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings	Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings The Corporation utilizes a variety of financial instruments in the normal course of business to meet the financial needs of its customers and to manage its own exposure to fluctuations in interest rates. These financial instruments include lending-related and other commitments (see below) as well as derivative instruments (see Note 10 ). The following is a summary of lending-related commitments. March 31, 2016 December 31, 2015 ($ in Thousands) Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale(1)(2) $ 7,315,642 $ 7,402,518 Commercial letters of credit(1) 7,782 9,945 Standby letters of credit(3) 278,740 296,508 1) These off-balance sheet financial instruments are exercisable at the market rate prevailing at the date the underlying transaction will be completed and, thus, are deemed to have no current fair value, or the fair value is based on fees currently charged to enter into similar agreements and is not material at March 31, 2016 or December 31, 2015 . 2) Interest rate lock commitments to originate residential mortgage loans held for sale are considered derivative instruments and are disclosed in Note 10 . 3) The Corporation has established a liability of $3 million at both March 31, 2016 and December 31, 2015 , as an estimate of the fair value of these financial instruments. Lending-related Commitments As a financial services provider, the Corporation routinely enters into commitments to extend credit. Such commitments are subject to the same credit policies and approval process accorded to loans made by the Corporation, with each customer’s creditworthiness evaluated on a case-by-case basis. The commitments generally have fixed expiration dates or other termination clauses and may require the payment of a fee. The Corporation’s exposure to credit loss in the event of nonperformance by the other party to these financial instruments is represented by the contractual amount of those instruments. The amount of collateral obtained, if deemed necessary by the Corporation upon extension of credit, is based on management’s credit evaluation of the customer. Since a significant portion of commitments to extend credit are subject to specific restrictive loan covenants or may expire without being drawn upon, the total commitment amounts do not necessarily represent future cash flow requirements. An allowance for unfunded commitments is maintained at a level believed by management to be sufficient to absorb estimated probable losses related to unfunded commitments (including unfunded loan commitments and letters of credit). The allowance for unfunded commitments totaled $24 million at both March 31, 2016 and December 31, 2015 , and is included in accrued expenses and other liabilities on the consolidated balance sheets. Lending-related commitments include commitments to extend credit, commitments to originate residential mortgage loans held for sale, commercial letters of credit, and standby letters of credit. Commitments to extend credit are legally binding agreements to lend to customers at predetermined interest rates, as long as there is no violation of any condition established in the contracts. Interest rate lock commitments to originate residential mortgage loans held for sale and forward commitments to sell residential mortgage loans are considered derivative instruments, and the fair value of these commitments is recorded on the consolidated balance sheets. The Corporation’s derivative and hedging activity is further described in Note 10 . Commercial and standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Commercial letters of credit are issued specifically to facilitate commerce and typically result in the commitment being drawn on when the underlying transaction is consummated between the customer and the third party, while standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party. Other Commitments The Corporation has principal investment commitments to provide capital-based financing to private and public companies through either direct investments in specific companies or through investment funds and partnerships. The timing of future cash requirements to fund such commitments is generally dependent on the investment cycle, whereby privately held companies are funded by private equity investors and ultimately sold, merged, or taken public through an initial offering, which can vary based on overall market conditions, as well as the nature and type of industry in which the companies operate. The Corporation also invests in unconsolidated projects including low-income housing, new market tax credit projects, and historic tax credit projects to promote the revitalization of primarily low-to-moderate-income neighborhoods throughout the local communities of its bank subsidiary. As a limited partner in these unconsolidated projects, the Corporation is allocated tax credits and deductions associated with the underlying projects. The aggregate carrying value of these investments at March 31, 2016 , was $53 million , compared to $52 million at December 31, 2015 , included in other assets on the consolidated balance sheets. Related to these investments, the Corporation had remaining commitments to fund of $62 million at March 31, 2016 , and $61 million at December 31, 2015 . Legal Proceedings The Corporation is party to various pending and threatened claims and legal proceedings arising in the normal course of business activities, some of which involve claims for substantial amounts. Although there can be no assurance as to the ultimate outcomes, the Corporation believes it has meritorious defenses to the claims asserted against it in its currently outstanding matters, including the matters described below, and with respect to such legal proceedings, intends to continue to defend itself vigorously. The Corporation will consider settlement of cases when, in management’s judgment, it is in the best interests of both the Corporation and its shareholders. On at least a quarterly basis, the Corporation assesses its liabilities and contingencies in connection with all pending or threatened claims and litigation, utilizing the most recent information available. On a matter by matter basis, an accrual for loss is established for those matters which the Corporation believes it is probable that a loss may be incurred and that the amount of such loss can be reasonably estimated. Once established, each accrual is adjusted as appropriate to reflect any subsequent developments. Accordingly, management’s estimate will change from time to time, and actual losses may be more or less than the current estimate. For matters where a loss is not probable, or the amount of the loss cannot be estimated, no accrual is established. Resolution of legal claims is inherently unpredictable, and in many legal proceedings various factors exacerbate this inherent unpredictability, including where the damages sought are unsubstantiated or indeterminate, it is unclear whether a case brought as a class action will be allowed to proceed on that basis, discovery is not complete, the proceeding is not yet in its final stages, the matters present legal uncertainties, there are significant facts in dispute, there are a large number of parties (including where it is uncertain how liability, if any, will be shared among multiple defendants), or there is a wide range of potential results. A lawsuit, R.J. ZAYED v. Associated Bank, N.A. , was filed in the United States District Court for the District of Minnesota on January 29, 2013. The lawsuit relates to a Ponzi scheme perpetrated by Oxford Global Partners and related entities (“Oxford”) and individuals and was brought by the receiver for Oxford. Oxford was a depository customer of Associated Bank (the "Bank"). The lawsuit claims that the Bank is liable for failing to uncover the Oxford Ponzi scheme, and specifically alleges the Bank aided and abetted (1) the fraudulent scheme; (2) a breach of fiduciary duty; (3) conversion; and (4) false representations and omissions. The lawsuit seeks unspecified consequential and punitive damages. The District Court granted the Bank’s motion to dismiss the complaint on September 30, 2013. On March 2, 2015, the U.S. Court of Appeals for the Eighth Circuit reversed the District Court and remanded the case back to the District Court for further proceedings. It is not possible for management to assess the probability of a material adverse outcome or reasonably estimate the amount of any potential loss at this time. A lawsuit by investors in the same Ponzi scheme, Herman Grad, et al v. Associated Bank, N.A., brought in Brown County, Wisconsin in October 2009 was dismissed by the circuit court, and the dismissal was affirmed by the Wisconsin Court of Appeals in June 2011 in an unpublished opinion. On May 22, 2015, the Bank entered into a Conciliation Agreement ("Conciliation Agreement") with the U.S. Department of Housing and Urban Development ("HUD") which resolved the HUD investigation into the Bank's lending practices during the years 2008-2010. The Bank's commitments under the Conciliation Agreement are spread over a three -year period and include commitments to do the following in minority communities: make mortgage loans of approximately $196 million ; open one branch and four loan production offices; establish special financing programs; make affordable home repair grants; engage in affirmative marketing outreach; provide financial education programs; and make grants to support community reinvestment training and education. The cost of these commitments will be spread over four calendar years and is not expected to have a material impact on the Corporation's financial condition or results of operation. Beginning in late 2013, the Corporation began reviewing a variety of legacy products provided by third parties, including debt protection and identity protection products. In connection with this review, the Corporation has made, and plans to make, remediation payments to affected customers and former customers, and has reserved accordingly. A variety of consumer products, including the legacy debt protection and identity protection products referred to above, and mortgage and deposit products, and certain fees and charges related to such products, have come under increased regulatory scrutiny. It is possible that regulatory authorities could bring enforcement actions, including civil money penalties, or take other actions against the Corporation and the Bank in regard to these consumer products. The Bank could also determine of its own accord, or be required by regulators, to refund or otherwise make remediation payments to customers in connection with these products. It is not possible at this time for management to assess the probability of a material adverse outcome or reasonably estimate the amount of any potential loss related to such matters. Two complaints were filed against the Bank on January 11, 2016 in the United States Bankruptcy Court for the Northern District of Illinois, Eastern Division in connection with the In re: World Marketing Chicago, LLC, et al Chapter 11 bankruptcy proceeding. In the first complaint, The Official Committee of Unsecured Creditors of World Marketing Chicago, LLC, et al v. Associated Bank, N.A., the plaintiff seeks to avoid guarantees and pledges of collateral given by the debtors to secure a revolving financing commitment of $6 million to the debtors’ parent company from the Bank. The plaintiff alleges a variety of legal theories under federal and state law, including fraudulent conveyance, preferential transfer and conversion, in support of its position. The plaintiff seeks return of approximately $4 million paid to the Bank and the avoidance of the security interest in the collateral securing the remaining approximately $1 million of indebtedness to the Bank. The Bank intends to vigorously defend this lawsuit. In the second complaint, American Funds Service Company v. Associated Bank, N.A., the plaintiff alleges that approximately $600,000 of funds it had advanced to the World Marketing entities to apply towards future postage fees was swept by the Bank from World Marketing’s bank accounts. Plaintiff seeks the return of such funds from the Bank under several theories, including Sec. 541(d) of the Bankruptcy Code, the creation of a resulting trust, and unjust enrichment. The Bank intends to vigorously defend this lawsuit. It is not possible for management to assess the probability of a material adverse outcome or reasonably estimate the amount of any potential loss at this time with respect to these two lawsuits. Mortgage Repurchase Reserve The Corporation sells residential mortgage loans to investors in the normal course of business. Residential mortgage loans sold to others are predominantly conventional residential first lien mortgages originated under our usual underwriting procedures, and are most often sold on a nonrecourse basis, primarily to the GSEs. The Corporation’s agreements to sell residential mortgage loans in the normal course of business usually require certain representations and warranties on the underlying loans sold, related to credit information, loan documentation, collateral, and insurability. Subsequent to being sold, if a material underwriting deficiency or documentation defect is discovered, the Corporation may be obligated to repurchase the loan or reimburse the GSEs for losses incurred (collectively, “make whole requests”). The make whole requests and any related risk of loss under the representations and warranties are largely driven by borrower performance. As a result of make whole requests, the Corporation has repurchased loans with principal balances of approximately $126,000 and $3 million during the three months ended March 31, 2016 and the year ended December 31, 2015 , respectively, and paid loss reimbursement or settlement claims of approximately $3,000 and $133,000 for the three months ended March 31, 2016 and the year ended December 31, 2015 , respectively. Make whole requests during 2015 and the first three months of 2016 generally arose from loans sold during the period of January 1, 2012 to March 31, 2016 , which total $7.9 billion at the time of sale, and consisted primarily of loans sold to GSEs. As of March 31, 2016 , approximately $5.7 billion of these sold loans remain outstanding. The balance in the mortgage repurchase reserve at the balance sheet date reflects the estimated amount of potential loss the Corporation could incur from repurchasing a loan, as well as loss reimbursements, indemnifications, and other settlement resolutions. The following summarizes the changes in the mortgage repurchase reserve. For the Three Months Ended March 31, 2016 For the Year Ended December 31, 2015 ($ in Thousands) Balance at beginning of period $ 1,197 $ 3,258 Repurchase provision expense 70 428 Adjustments to provision expense — (2,450 ) Charge offs, net (3 ) (39 ) Balance at end of period $ 1,264 $ 1,197 The Corporation may also sell residential mortgage loans with limited recourse (limited in that the recourse period ends prior to the loan’s maturity, usually after certain time and / or loan paydown criteria have been met), whereby repurchase could be required if the loan had defined delinquency issues during the limited recourse periods. At March 31, 2016 , and December 31, 2015 , there were approximately $60 million and $68 million , respectively, of residential mortgage loans sold with such recourse risk. There have been limited instances and immaterial historical losses on repurchases for recourse under the limited recourse criteria. The Corporation has a subordinate position to the FHLB in the credit risk on residential mortgage loans it sold to the FHLB in exchange for a monthly credit enhancement fee. The Corporation has not sold loans to the FHLB with such credit risk retention since February 2005. At March 31, 2016 and December 31, 2015 , there were $122 million and $132 million , respectively, of such residential mortgage loans with credit risk recourse, upon which there have been negligible historical losses to the Corporation.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value represents the estimated price at which an orderly transaction to sell an asset or to transfer a liability would take place between market participants at the measurement date under current market conditions (i.e., an exit price concept). Following is a description of the valuation methodologies used for the Corporation’s more significant instruments measured on a recurring basis at fair value, including the general classification of such instruments pursuant to the valuation hierarchy. Investment securities available for sale : Where quoted prices are available in an active market, investment securities are classified in Level 1 of the fair value hierarchy. If quoted market prices are not available for the specific security, then fair values are estimated by using pricing models, quoted prices of securities with similar characteristics or discounted cash flows, with consideration given to the nature of the quote and the relationship of recently evidenced market activity to the fair value estimate, and are classified in Level 2 of the fair value hierarchy. Lastly, in certain cases where there is limited activity or less transparency around inputs to the estimated fair value, securities are classified within Level 3 of the fair value hierarchy. To validate the fair value estimates, assumptions, and controls, the Corporation looks to transactions for similar instruments and utilizes independent pricing provided by third party vendors or brokers and relevant market indices. While none of these sources are solely indicative of fair value, they serve as directional indicators for the appropriateness of the Corporation’s fair value estimates. The Corporation has determined that the fair value measures of its investment securities are classified predominantly within Level 1 or 2 of the fair value hierarchy. See Note 6 for additional disclosure regarding the Corporation’s investment securities. Derivative financial instruments (interest rate-related instruments ): The Corporation has used, and may use again in the future, interest rate swaps to manage its interest rate risk. In addition, the Corporation offers customer interest rate-related instruments (swaps and caps) to service our customers’ needs, for which the Corporation simultaneously enters into offsetting derivative financial instruments (i.e., mirror interest rate-related instruments) with third parties to manage its interest rate risk associated with these financial instruments. The valuation of the Corporation’s derivative financial instruments is determined using discounted cash flow analysis on the expected cash flows of each derivative and, also includes a nonperformance / credit risk component (credit valuation adjustment). See Note 10 for additional disclosure regarding the Corporation’s interest rate-related instruments. The discounted cash flow analysis component in the fair value measurements reflects the contractual terms of the derivative financial instruments, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. More specifically, the fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments), with the variable cash payments (or receipts) based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. Likewise, the fair values of interest rate options (i.e., interest rate caps) are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates fall below (or rise above) the strike rate of the floors (or caps), with the variable interest rates used in the calculation of projected receipts on the floor (or cap) based on an expectation of future interest rates derived from observable market interest rate curves and volatilities. The Corporation also incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative financial instruments for the effect of nonperformance risk, the Corporation has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. While the Corporation has determined that the majority of the inputs used to value its derivative financial instruments fall within Level 2 of the fair value hierarchy, the credit valuation adjustments utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. The Corporation has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions as of March 31, 2016, and December 31, 2015, and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivative financial instruments. Therefore, the Corporation has determined that the fair value measures of its derivative financial instruments in their entirety are classified within Level 2 of the fair value hierarchy. Derivative financial instruments (foreign currency exchange forwards ): The Corporation provides foreign currency exchange services to customers. In addition, the Corporation may enter into a foreign currency exchange forward to mitigate the exchange rate risk attached to the cash flows of a loan or as an offsetting contract to a forward entered into as a service to our customer. The valuation of the Corporation’s foreign currency exchange forwards is determined using quoted prices of foreign currency exchange forwards with similar characteristics, with consideration given to the nature of the quote and the relationship of recently evidenced market activity to the fair value estimate, and are classified in Level 2 of the fair value hierarchy. See Note 10 for additional disclosures regarding the Corporation’s foreign currency exchange forwards. Derivative financial instruments (commodity contracts ): The Corporation enters into commodity contracts to manage commercial customers' exposure to fluctuating commodity prices, for which the Corporation simultaneously enters into offsetting derivative financial instruments (i.e., mirror commodity contracts) with third parties to manage its risk associated with these financial instruments. The valuation of the Corporation’s commodity contracts is determined using quoted prices of the underlying instrument, and are classified in Level 2 of the fair value hierarchy. See Note 10 for additional disclosures regarding the Corporation’s commodity contracts. Derivative financial instruments (mortgage derivatives) : Mortgage derivatives include interest rate lock commitments to originate residential mortgage loans held for sale to individual customers and forward commitments to sell residential mortgage loans to various investors. The Corporation relies on an internal valuation model to estimate the fair value of its interest rate lock commitments to originate residential mortgage loans held for sale, which includes grouping the interest rate lock commitments by interest rate and terms, applying an estimated pull-through rate based on historical experience, and then multiplying by quoted investor prices determined to be reasonably applicable to the loan commitment groups based on interest rate, terms, and rate lock expiration dates of the loan commitment groups. The Corporation also relies on an internal valuation model to estimate the fair value of its forward commitments to sell residential mortgage loans (i.e., an estimate of what the Corporation would receive or pay to terminate the forward delivery contract based on market prices for similar financial instruments), which includes matching specific terms and maturities of the forward commitments against applicable investor pricing available. While there are Level 2 and 3 inputs used in the valuation models, the Corporation has determined that the majority of the inputs significant in the valuation of both of the mortgage derivatives fall within Level 3 of the fair value hierarchy. See Note 10 for additional disclosure regarding the Corporation’s mortgage derivatives. Following is a description of the valuation methodologies used for the Corporation’s more significant instruments measured on a nonrecurring basis at the lower of amortized cost or estimated fair value, including the general classification of such instruments pursuant to the valuation hierarchy. Loans Held for Sale: Loans held for sale, which consist generally of current production of certain fixed-rate, first-lien residential mortgage loans, are carried at the lower of cost or estimated fair value. The estimated fair value was based on what secondary markets are currently offering for portfolios with similar characteristics, which the Corporation classifies as a Level 2 nonrecurring fair value measurement. Impaired Loans: The Corporation considers a loan impaired when it is probable that the Corporation will be unable to collect all amounts due according to the original contractual terms of the note agreement, including both principal and interest. Management has determined that commercial and consumer loan relationships that have nonaccrual status or have had their terms restructured in a troubled debt restructuring meet this impaired loan definition. For individually evaluated impaired loans, the amount of impairment is based upon the present value of expected future cash flows discounted at the loan’s effective interest rate, the estimated fair value of the underlying collateral for collateral-dependent loans, or the estimated liquidity of the note. See Note 7 for additional information regarding the Corporation’s impaired loans. Mortgage servicing rights : Mortgage servicing rights do not trade in an active, open market with readily observable prices. While sales of mortgage servicing rights do occur, the precise terms and conditions typically are not readily available to allow for a “quoted price for similar assets” comparison. Accordingly, the Corporation utilizes an independent valuation from a third party which uses a discounted cash flow model to estimate the fair value of its mortgage servicing rights. The valuation model incorporates prepayment assumptions to project mortgage servicing rights cash flows based on the current interest rate scenario, which is then discounted to estimate an expected fair value of the mortgage servicing rights. The valuation model considers portfolio characteristics of the underlying mortgages, contractually specified servicing fees, prepayment assumptions, discount rate assumptions, delinquency rates, late charges, other ancillary revenue, costs to service, and other economic factors. The Corporation periodically reviews and assesses the underlying inputs and assumptions used in the model. In addition, the Corporation compares its fair value estimates and assumptions to observable market data for mortgage servicing rights, where available, and to recent market activity and actual portfolio experience. Due to the nature of the valuation inputs, mortgage servicing rights are classified within Level 3 of the fair value hierarchy. The Corporation uses the amortization method (i.e., lower of amortized cost or estimated fair value measured on a nonrecurring basis), not fair value measurement accounting, for its mortgage servicing rights assets. See Note 8 for additional disclosure regarding the Corporation’s mortgage servicing rights. The table below presents the Corporation’s investment securities available for sale and derivative financial instruments measured at fair value on a recurring basis as of March 31, 2016 and December 31, 2015 , aggregated by the level in the fair value hierarchy within which those measurements fall. Assets and Liabilities Measured at Fair Value on a Recurring Basis Fair Value Hierarchy March 31, 2016 December 31, 2015 ($ in Thousands) Assets: Investment securities available for sale: U.S. Treasury securities Level 1 $ 1,000 $ 997 Residential mortgage-related securities: FNMA / FHLMC Level 2 1,303,404 1,414,626 GNMA Level 2 1,547,255 1,590,003 Private-label Level 2 1,512 1,709 GNMA commercial mortgage-related securities Level 2 2,047,865 1,955,310 Other securities (debt and equity) Level 1 1,605 1,569 Other securities (debt and equity) Level 2 3,000 3,000 Other securities (debt and equity) Level 3 200 200 Total investment securities available for sale Level 1 2,605 2,566 Total investment securities available for sale Level 2 4,903,036 4,964,648 Total investment securities available for sale Level 3 200 200 Interest rate-related instruments Level 2 47,780 29,391 Foreign currency exchange forwards Level 2 4,203 1,532 Interest rate lock commitments to originate residential mortgage loans held for sale Level 3 2,689 958 Forward commitments to sell residential mortgage loans Level 3 — 403 Commodity contracts Level 2 1,104 1,269 Purchased options (time deposit) Level 2 2,228 2,715 Liabilities: Interest rate-related instruments Level 2 50,145 30,886 Foreign currency exchange forwards Level 2 4,097 1,398 Forward commitments to sell residential mortgage loans Level 3 1,732 — Commodity contracts Level 2 981 1,146 Written options (time deposit) Level 2 2,228 2,715 The table below presents a rollforward of the balance sheet amounts for the three months ended March 31, 2016 and the year ended December 31, 2015 , for financial instruments measured on a recurring basis and classified within Level 3 of the fair value hierarchy. Investment Securities Available for Sale Derivative Financial Instruments ($ in Thousands) Balance December 31, 2014 $ 200 $ (488 ) Total net gains included in income: Mortgage derivative gain — 1,849 Balance December 31, 2015 $ 200 $ 1,361 Total net losses included in income: Mortgage derivative loss — (404 ) Balance March 31, 2016 $ 200 $ 957 For Level 3 assets and liabilities measured at fair value on a recurring or nonrecurring basis as of March 31, 2016 , the Corporation utilized the following valuation techniques and significant unobservable inputs. Derivative financial instruments (mortgage derivative — interest rate lock commitments to originate residential mortgage loans held for sale) : The significant unobservable input used in the fair value measurement of the Corporation’s mortgage derivative interest rate lock commitments is the closing ratio, which represents the percentage of loans currently in a lock position which management estimates will ultimately close. The closing ratio calculation takes into consideration historical data and loan-level data, particularly the change in the current interest rates from the time of initial rate lock. The closing ratio is periodically reviewed for reasonableness and reported to the Associated Mortgage Group Risk Committee. At March 31, 2016 , the closing ratio was 89% . Impaired loans : For individually evaluated impaired loans, the amount of impairment is based upon the present value of expected future cash flows discounted at the loan’s effective interest rate, the estimated fair value of the underlying collateral for collateral-dependent loans, or the estimated liquidity of the note, resulting in an average discount of 10% to 15% . Mortgage servicing rights : The discounted cash flow analyses that generate expected market prices utilize the observable characteristics of the mortgage servicing rights portfolio, as well as certain unobservable valuation parameters. The significant unobservable inputs used in the fair value measurement of the Corporation’s mortgage servicing rights are the weighted average constant prepayment rate and weighted average discount rate, which were 15.2% and 9.6% at March 31, 2016 , respectively. Significant increases (decreases) in any of those inputs in isolation could result in a significantly lower (higher) fair value measurement. These parameter assumptions fall within a range that the Corporation, in consultation with an independent third party, believes purchasers of servicing would apply to such portfolios sold into the current secondary servicing market. Discussions are held with members from Treasury and Consumer Banking to reconcile the fair value estimates and the key assumptions used by the respective parties in arriving at those estimates. The Associated Mortgage Group Risk Committee is responsible for providing control over the valuation methodology and key assumptions. To assess the reasonableness of the fair value measurement, the Corporation also compares the fair value and constant prepayment rate to a value calculated by an independent third party on an annual basis. The table below presents the Corporation’s loans held for sale, impaired loans, and mortgage servicing rights measured at fair value on a nonrecurring basis as of March 31, 2016 and December 31, 2015 , aggregated by the level in the fair value hierarchy within which those measurements fall. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Income Statement Category of Adjustment Recognized in Income ($ in Thousands) Fair Value Hierarchy Fair Value March 31, 2016 Assets: Loans held for sale (2) Level 2 $ 129,398 Mortgage banking, net $ — Impaired loans (1) Level 3 84,664 Provision for credit losses (15,097 ) Mortgage servicing rights Level 3 61,410 Mortgage banking, net (909 ) December 31, 2015 Assets: Loans held for sale Level 2 $ 124,915 Mortgage banking, net $ (155 ) Impaired loans (1) Level 3 41,891 Provision for credit losses (7,796 ) Mortgage servicing rights Level 3 70,686 Mortgage banking, net 425 (1) Represents individually evaluated impaired loans, net of the related allowance for loan losses. (2) Loans held for sale are carried at the lower of cost or estimated fair value. At March 31, 2016, the estimated fair value exceeded the cost and therefore there was no adjustment recognized in Income. Certain nonfinancial assets measured at fair value on a nonrecurring basis include other real estate owned (upon initial recognition or subsequent impairment), nonfinancial assets and nonfinancial liabilities measured at fair value in the second step of a goodwill impairment test, and intangible assets and other nonfinancial long-lived assets measured at fair value for impairment assessment. During the first three months of 2016 and the full year 2015 , certain other real estate owned, upon initial recognition, was re-measured and reported at fair value through a charge off to the allowance for loan losses based upon the estimated fair value of the other real estate owned, less estimated selling costs. The fair value of other real estate owned, upon initial recognition or subsequent impairment, was estimated using appraised values, which the Corporation classifies as a Level 2 nonrecurring fair value measurement. Other real estate owned measured at fair value upon initial recognition totaled approximately $3 million for the first three months of 2016 and $11 million for the year ended December 31, 2015 , respectively. In addition to other real estate owned measured at fair value upon initial recognition, the Corporation also recorded write-downs to the balance of other real estate owned for subsequent impairment of less than $1 million and $3 million to foreclosure / OREO expense, net for the three months ended 2016 and the year ended December 31, 2015 , respectively. Fair Value of Financial Instruments: The Corporation is required to disclose estimated fair values for its financial instruments. Fair value estimates, methods, and assumptions are set forth below for the Corporation’s financial instruments. The estimated fair values of the Corporation’s financial instruments were as follows. March 31, 2016 December 31, 2015 Fair Value Hierarchy Level Carrying Amount Fair Value Carrying Amount Fair Value ($ in Thousands) Financial assets: Cash and due from banks Level 1 $ 287,183 $ 287,183 $ 374,921 $ 374,921 Interest-bearing deposits in other financial institutions Level 1 68,025 68,025 79,764 79,764 Federal funds sold and securities purchased under agreements to resell Level 1 20,200 20,200 19,000 19,000 Investment securities held to maturity Level 2 1,176,821 1,204,345 1,168,230 1,184,442 Investment securities available for sale Level 1 2,605 2,605 2,566 2,566 Investment securities available for sale Level 2 4,903,036 4,903,036 4,964,648 4,964,648 Investment securities available for sale Level 3 200 200 200 200 FHLB and Federal Reserve Bank stocks Level 2 181,853 181,853 147,240 147,240 Loans held for sale Level 2 128,339 129,398 124,915 124,915 Loans, net Level 3 18,949,870 19,025,680 18,440,079 18,389,832 Bank owned life insurance Level 2 580,583 580,583 583,019 583,019 Derivatives (trading and other assets) Level 2 55,315 55,315 34,907 34,907 Derivatives (trading and other assets) Level 3 2,689 2,689 1,361 1,361 Financial liabilities: Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts Level 3 $ 19,117,418 $ 19,117,418 $ 19,444,863 $ 19,444,863 Brokered CDs and other time deposits Level 2 1,568,042 1,576,714 1,562,802 1,564,464 Short-term funding Level 2 1,417,408 1,417,408 834,416 834,416 Long-term funding Level 2 2,861,316 2,925,447 2,676,164 2,728,112 Standby letters of credit (1) Level 2 2,746 2,746 2,954 2,954 Derivatives (trading and other liabilities) Level 2 57,451 57,451 36,145 36,145 Derivatives (trading and other liabilities) Level 3 1,732 1,732 — — (1) The commitment on standby letters of credit was $279 million and $297 million at March 31, 2016 and December 31, 2015 , respectively. See Note 12 for additional information on the standby letters of credit and for information on the fair value of lending-related commitments. Cash and due from banks, interest-bearing deposits in other financial institutions, and federal funds sold and securities purchased under agreements to resell— For these short-term instruments, the carrying amount is a reasonable estimate of fair value. Investment securities (held to maturity and available for sale)— The fair value of investment securities is based on quoted prices in active markets, or if quoted prices are not available for a specific security, then fair values are estimated by using pricing models, quoted prices of securities with similar characteristics, or discounted cash flows. FHLB and Federal Reserve Bank stocks— The carrying amount is a reasonable fair value estimate for the Federal Reserve Bank and Federal Home Loan Bank stocks given their “restricted” nature (i.e., the stock can only be sold back to the respective institutions (Federal Home Loan Bank or Federal Reserve Bank) or another member institution at par). Loans held for sale— The fair value estimation process for the loans held for sale portfolio is segregated by loan type. The estimated fair value was based on what secondary markets are currently offering for portfolios with similar characteristics. Loans, net— The fair value estimation process for the loan portfolio uses an exit price concept and reflects discounts the Corporation believes are consistent with liquidity discounts in the market place. Fair values are estimated for portfolios of loans with similar financial characteristics. Loans are segregated by type such as commercial and industrial, real estate construction, commercial real estate (owner occupied and investor), residential mortgage, home equity, and other consumer. The fair value of loans is estimated by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for similar maturities. The fair value analysis also included other assumptions to estimate fair value, intended to approximate those a market participant would use in an orderly transaction, with adjustments for discount rates, interest rates, liquidity, and credit spreads, as appropriate. Bank owned life insurance— The fair value of bank owned life insurance approximates the carrying amount, because upon liquidation of these investments, the Corporation would receive the cash surrender value which equals the carrying amount. Deposits— The fair value of deposits with no stated maturity such as noninterest-bearing demand, savings, interest-bearing demand, and money market accounts, is equal to the amount payable on demand as of the balance sheet date. The fair value of Brokered CDs and other time deposits is based on the discounted value of contractual cash flows. The discount rate is estimated using the rates currently offered for deposits of similar remaining maturities. However, if the estimated fair value of Brokered CDs and other time deposits is less than the carrying value, the carrying value is reported as the fair value. Short-term funding— The carrying amount is a reasonable estimate of fair value for existing short-term funding. Long-term funding— Rates currently available to the Corporation for debt with similar terms and remaining maturities are used to estimate the fair value of existing long-term funding. Standby letters of credit— The fair value of standby letters of credit represents deferred fees arising from the related off-balance sheet financial instruments. These deferred fees approximate the fair value of these instruments and are based on several factors, including the remaining terms of the agreement and the credit standing of the customer. Derivatives (trading and other) Interest rate-related instruments— The fair value of interest rate-related instruments is determined using discounted cash flow analysis on the expected cash flows of each derivative. The Corporation also incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. Foreign currency exchange forwards— The fair value of the Corporation’s foreign currency exchange forwards is determined using quoted prices of foreign currency exchange forwards with similar characteristics, with consideration given to the nature of the quote and the relationship of recently evidenced market activity to the fair value estimate. Purchased and written options— The fair value of the Corporation’s purchased and written options is determined using quoted prices of the underlying stocks. Commodity contracts— The fair value of the Corporation’s commodity contracts is determined using quoted prices of the underlying instruments. Interest rate lock commitments to originate residential mortgage loans held for sale— The Corporation relies on an internal valuation model to estimate the fair value of its interest rate lock commitments to originate residential mortgage loans held for sale, which includes grouping the interest rate lock commitments by interest rate and terms, applying an estimated pull-through rate based on historical experience, and then multiplying by quoted investor prices determined to be reasonably applicable to the loan commitment groups based on interest rate, terms, and rate lock expiration dates of the loan commitment groups. Forward commitments to sell residential mortgage loans— The Corporation relies on an internal valuation model to estimate the fair value of its forward commitments to sell residential mortgage loans (i.e., an estimate of what the Corporation would receive or pay to terminate the forward delivery contract based on market prices for similar financial instruments), which includes matching specific terms and maturities of the forward commitments against applicable investor pricing available. Limitations— Fair value estimates are made at a specific point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the Corporation’s entire holdings of a particular financial instrument. Because no market exists for a significant portion of the Corporation’s financial instruments, fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments, and other factors. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and, therefore, cannot be determined with precision. Changes in assumptions could significantly affect the estimates.

Retirement Plans

Retirement Plans	3 Months Ended
	Mar. 31, 2016
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Retirement Plans	Retirement Plans The Corporation has a noncontributory defined benefit retirement plan (the Retirement Account Plan (“RAP”)) covering substantially all full-time employees. The benefits are based primarily on years of service and the employee’s compensation paid. Employees of acquired entities generally participate in the RAP after consummation of the business combinations. Any retirement plans of acquired entities are typically merged into the RAP after completion of the mergers, and credit is usually given to employees for years of service at the acquired institution for vesting and eligibility purposes. The Corporation also provides healthcare access for eligible retired employees in its Postretirement Plan (the “Postretirement Plan”). Retirees who are at least 55 years of age with 5 years of service are eligible to participate in the Postretirement Plan. The Corporation has no plan assets attributable to the Postretirement Plan. The Corporation reserves the right to terminate or make changes to the Postretirement Plan at any time. The components of net periodic benefit cost for the RAP and Postretirement Plans for three months ended March 31, 2016 and 2015 were as follows. Three Months Ended March 31, 2016 2015 ($ in Thousands) Components of Net Periodic Benefit Cost Pension Plan: Service cost $ 1,725 $ 3,063 Interest cost 1,780 1,642 Expected return on plan assets (5,065 ) (5,350 ) Amortization of prior service cost 13 13 Amortization of actuarial loss 482 532 Total net pension cost $ (1,065 ) $ (100 ) Postretirement Plan: Interest cost $ 36 $ 35 Total net periodic benefit cost $ 36 $ 35

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Corporation utilizes a risk-based internal profitability measurement system to provide strategic business unit reporting. The profitability measurement system is based on internal management methodologies designed to produce consistent results and reflect the underlying economics of the units. Certain strategic business units have been combined for segment information reporting purposes where the nature of the products and services, the type of customer and the distribution of those products and services are similar. The three reportable segments are Corporate and Commercial Specialty; Community, Consumer, and Business; and Risk Management and Shared Services. The financial information of the Corporation’s segments has been compiled utilizing the accounting policies described in the Corporation’s 2015 Annual Report on Form 10-K, with certain exceptions. The more significant of these exceptions are described herein. The Corporation allocates net interest income using an internal funds transfer pricing ("FTP") methodology that charges users of funds (assets) and credits providers of funds (liabilities, primarily deposits) based on the maturity, prepayment and / or repricing characteristics of the assets and liabilities. The net effect of this allocation is recorded in the Risk Management and Shared Services segment. During 2015, the Corporation adopted enhanced FTP methodology utilizing, new, more granular deposit information which incorporated the additional dimension of vintage (based on time from when the deposit account was opened) for determining the funds credit for non-maturity deposits. The new deposit information demonstrated that deposit accounts with the Corporation for a longer period of time had a lower attrition rate, warranting a higher crediting rate (based on a longer-term segment of the yield curve) to reflect the long-term value such deposits provide to the Corporation. A credit provision is allocated to segments based on the expected long-term annual net charge off rates attributable to the credit risk of loans managed by the segment during the period. In contrast, the level of the consolidated provision for credit losses is determined based on an incurred loss model using the methodologies described in the Corporation’s 2015 Annual Report on Form 10-K to assess the overall appropriateness of the allowance for loan losses. The net effect of the credit provision is recorded in Risk Management and Shared Services. Indirect expenses incurred by certain centralized support areas are allocated to segments based on actual usage (for example, volume measurements) and other criteria. Certain types of administrative expense and bank-wide expense accruals (including amortization of core deposit and other intangible assets associated with acquisitions) are generally not allocated to segments. Income taxes are allocated to segments based on the Corporation’s estimated effective tax rate, with certain segments adjusted for any tax-exempt income or non-deductible expenses. Equity is allocated to the segments based on regulatory capital requirements and in proportion to an assessment of the inherent risks associated with the business of the segment (including interest, credit and operating risk). The management accounting policies and processes utilized in compiling segment financial information are highly subjective and, unlike financial accounting, are not based on authoritative guidance similar to U.S. generally accepted accounting principles. As a result, reported segments and the financial information of the reported segments are not necessarily comparable with similar information reported by other financial institutions. Furthermore, changes in management structure or allocation methodologies and procedures may result in changes in previously reported segment financial data. A brief description of each business segment is presented below. A more in-depth discussion of these segments can be found in the Segment Reporting footnote in the Corporation’s 2015 Annual Report on Form 10-K. There have been no changes in the Corporation's segments since December 31, 2015. The Corporate and Commercial Specialty segment serves a wide range of customers including larger businesses, developers, not-for-profits, municipalities, and financial institutions. The Community, Consumer, and Business segment serves individuals, as well as small and mid-sized businesses. The Risk Management and Shared Services segment includes key shared operational functions and also includes residual revenue and expenses, representing the difference between actual amounts incurred and the amounts allocated to operating segments, including interest rate risk residuals (FTP mismatches) and credit risk and provision residuals (long-term credit charge mismatches). Information about the Corporation’s segments is presented below. Segment Income Statement Data ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Three Months Ended March 31, 2016 Net interest income $ 79,164 $ 85,605 $ 7,218 $ 171,987 Noninterest income 11,613 63,748 7,831 83,192 Total revenue 90,777 149,353 15,049 255,179 Credit provision* 12,739 6,142 1,119 20,000 Noninterest expense 34,403 121,295 18,273 173,971 Income (loss) before income taxes 43,635 21,916 (4,343 ) 61,208 Income tax expense (benefit) 14,579 7,670 (3,575 ) 18,674 Net income (loss) $ 29,056 $ 14,246 $ (768 ) $ 42,534 Return on average allocated capital (ROCET1)** 11.3 % 9.1 % (5.0 )% 8.6 % Three Months Ended March 31, 2015 Net interest income $ 75,691 $ 86,357 $ 5,765 $ 167,813 Noninterest income 12,613 65,344 1,856 79,813 Total revenue 88,304 151,701 7,621 247,626 Credit provision* 9,526 7,071 (12,097 ) 4,500 Noninterest expense 34,460 118,373 21,159 173,992 Income (loss) before income taxes 44,318 26,257 (1,441 ) 69,134 Income tax expense (benefit) 15,368 9,190 (2,096 ) 22,462 Net income $ 28,950 $ 17,067 $ 655 $ 46,672 Return on average allocated capital (ROCET1)** 12.5 % 10.7 % (1.1 )% 10.2 % Segment Balance Sheet Data ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Three Months Ended March 31, 2016 Average earning assets $ 9,720,028 $ 9,120,319 $ 6,432,026 $ 25,272,373 Average loans 9,711,221 9,119,020 92,589 18,922,830 Average deposits 5,918,341 11,100,195 3,556,638 20,575,174 Average allocated capital (CET1)** $ 1,031,659 $ 627,211 $ 237,611 $ 1,896,481 Three Months Ended March 31, 2015 Average earning assets $ 9,218,844 $ 8,525,399 $ 6,403,783 $ 24,148,026 Average loans 9,210,992 8,525,399 78,724 17,815,115 Average deposits 5,421,541 10,522,618 3,111,037 19,055,196 Average allocated capital (CET1)** $ 942,764 $ 647,375 $ 214,078 $ 1,804,217 * The consolidated credit provision is equal to the actual reported provision for credit losses. ** The Federal Reserve establishes capital adequacy requirements for the Corporation, including Tier 1 capital. Tier 1 capital is comprised of common capital and certain redeemable, non-cumulative preferred stock. Average allocated capital represents average common equity Tier 1 which is defined as average Tier 1 capital excluding qualifying perpetual preferred stock and qualifying trust preferred securities. This is a non-GAAP financial measure. For segment reporting purposes, the ROCET1 reflects return on average allocated common equity Tier 1 (“CET1”). The ROCET1 for the Risk Management and Shared Services segment and the Consolidated Total is inclusive of the annualized effect of the preferred stock dividends.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following table summarizes the components of accumulated other comprehensive income (loss) at March 31, 2016 and 2015 , changes during the three month periods then ended, and reclassifications out of accumulated other comprehensive income (loss) during the three month periods ended March 31, 2016 and 2015 , respectively. ($ in Thousands) Investments Securities Available For Sale Defined Benefit Pension and Post Retirement Obligations Accumulated Other Comprehensive Income (Loss) Balance January 1, 2016 $ 459 $ (33,075 ) $ (32,616 ) Other comprehensive income before reclassifications 60,422 — 60,422 Amounts reclassified from accumulated other comprehensive income (loss): Investment securities gain, net (3,098 ) — (3,098 ) Personnel expense — 495 495 Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities) (1,572 ) — (1,572 ) Income tax expense (21,275 ) (189 ) (21,464 ) Net other comprehensive income during period 34,477 306 34,783 Balance March 31, 2016 $ 34,936 $ (32,769 ) $ 2,167 Balance January 1, 2015 $ 18,512 $ (23,362 ) $ (4,850 ) Other comprehensive income before reclassifications 47,418 — 47,418 Amounts reclassified from accumulated other comprehensive income: Personnel expense — 545 545 Income tax expense (18,105 ) (208 ) (18,313 ) Net other comprehensive income during period 29,313 337 29,650 Balance March 31, 2015 $ 47,825 $ (23,025 ) $ 24,800

New Accounting Pronouncements25

New Accounting Pronouncements Adopted (Policies)	3 Months Ended
	Mar. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements Adopted	In September 2015, the FASB issued an amendment to simplify the accounting for measurement adjustments to prior business combinations. The amendment requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The acquirer must record, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendment also requires an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. This amendment was effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The Corporation adopted the accounting standard during the first quarter of 2016, as required, and with no material impact on its results of operations, financial position, or liquidity. In May 2015, the FASB issued an amendment to eliminate the requirement to categorize investments measured using the net asset value per share ("NAV") practical expedient in the fair value hierarchy table. Entities will be required to disclose the fair value of investments measured using the NAV practical expedient so that financial statement users can reconcile amounts reported in the fair value hierarchy table to amounts reported on the balance sheet. The Corporation adopted the accounting standard during the first quarter of 2016, as required, with no material impact on its results of operations, financial position, or liquidity. In April 2015, the FASB issued an amendment to provide guidance to customers about whether a cloud computing arrangement included a software license. If the cloud computing arrangement includes a software license, then the customer should account for the software license element consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. This amendment was effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. The Corporation adopted the accounting standard on a prospective basis during the first quarter of 2016, as required, and with no material impact on its results of operations, financial position, or liquidity. In April 2015, the FASB issued an amendment to simplify the presentation of debt issuance costs. This amendment requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. In August 2015, the FASB expanded this amendment to include SEC staff views related to debt issuance costs associated with line-of-credit arrangements. The SEC staff would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. This amendment required retrospective application and was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The Corporation adopted the accounting standard during the first quarter of 2016. All prior periods have been restated to reflect this change in presentation, resulting in a $3 million reduction to other assets and a corresponding $3 million reduction to long-term funding on the balance sheet compared to the amounts originally reported at December 31, 2015. See "Consolidated Balance Sheets" and Note 9 for additional information on the reclassification of debt issuance costs. In February 2015, the FASB issued an amendment to modify existing consolidation guidance for reporting companies that are required to evaluate whether they should consolidate legal entities. The new standard will place more emphasis on risk of loss when determining a controlling financial interest. Frequency in the application of related-party guidance for determining a controlling financial interest will be reduced. Also, consolidation conclusions for public and private companies among several industries that make use of limited partnerships or VIEs will be changed. This amendment was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The Corporation adopted the accounting standard during the first quarter of 2016, as required, and with no material impact on its results of operations, financial position, or liquidity. In January 2015, the FASB issued an amendment to eliminate from U.S. GAAP the concept of extraordinary items. Presently, an event or transaction is presumed to be an ordinary and usual activity of the reporting entity unless evidence clearly supports its classification as an extraordinary item. If an event or transaction meets the criteria for extraordinary classification, an entity is required to segregate the extraordinary item from the results of ordinary operations and show the item separately in the income statement, net of tax, after income from continuing operations. This amended guidance will prohibit separate disclosure of extraordinary items in the income statement. This amendment was effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The Corporation adopted the accounting standard during the first quarter of 2016, as required, with no material impact. In June 2014, the FASB issued an amendment to the stock compensation accounting guidance to clarify that a performance target that affects vesting of a share-based payment and that could be achieved after the requisite service period be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. This amendment was effective for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2015. The Corporation adopted the accounting standard on a prospective basis during the first quarter of 2016, as required, with no material impact on its results of operations, financial position, or liquidity.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Calculations for basic and diluted earnings per common share	Presented below are the calculations for basic and diluted earnings per common share. For the Three Months Ended March 31, 2016 2015 (In thousands, except per share data) Net income $ 42,534 $ 46,672 Preferred stock dividends (2,198 ) (1,228 ) Net income available to common equity $ 40,336 $ 45,444 Common shareholder dividends (16,203 ) (15,166 ) Unvested share-based payment awards (206 ) (114 ) Undistributed earnings $ 23,927 $ 30,164 Undistributed earnings allocated to common shareholders 23,686 29,886 Undistributed earnings allocated to unvested share-based payment awards 241 278 Undistributed earnings $ 23,927 $ 30,164 Basic Distributed earnings to common shareholders $ 16,203 $ 15,166 Undistributed earnings allocated to common shareholders 23,686 29,886 Total common shareholders earnings, basic $ 39,889 $ 45,052 Diluted Distributed earnings to common shareholders $ 16,203 $ 15,166 Undistributed earnings allocated to common shareholders 23,686 29,886 Total common shareholders earnings, diluted $ 39,889 $ 45,052 Weighted average common shares outstanding 148,601 150,070 Effect of dilutive common stock awards 853 1,094 Diluted weighted average common shares outstanding 149,454 151,164 Basic earnings per common share $ 0.27 $ 0.30 Diluted earnings per common share $ 0.27 $ 0.30

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Fair value assumptions of stock options	The following assumptions were used in estimating the fair value for options granted in the first three months of 2016 and full year 2015 . 2016 2015 Dividend yield 2.50 % 2.00 % Risk-free interest rate 2.00 % 2.00 % Weighted average expected volatility 25.00 % 20.00 % Weighted average expected life 5.5 years 6.0 years Weighted average per share fair value of options $3.36 $3.08
Summary of Company's Stock Option Activities	A summary of the Corporation’s stock option activity for the year ended December 31, 2015 , and the three month ended March 31, 2016 is presented below. Stock Options Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (000s) Outstanding at December 31, 2014 7,847,338 $ 18.34 Granted 1,348,504 17.95 Exercised (1,351,646 ) 13.90 Forfeited or expired (1,215,053 ) 29.13 Outstanding at December 31, 2015 6,629,143 $ 17.22 6.24 $ 18,730 Options Exercisable at December 31, 2015 4,190,245 $ 17.25 4.93 $ 14,873 Granted 1,302,298 $ 17.45 Exercised (96,602 ) 13.60 Forfeited or expired (48,190 ) 17.75 Outstanding at March 31, 2016 7,786,649 $ 17.30 6.61 $ 14,682 Options Exercisable at March 31, 2016 4,907,257 $ 17.22 5.18 $ 12,950
Summary of Company's Nonvested Stock Option Activities	The following table summarizes information about the Corporation’s nonvested stock option activity for the year ended December 31, 2015 , and for the three months ended March 31, 2016 . Nonvested Stock Options Shares Weighted Average Grant Date Fair Value Nonvested at December 31, 2014 2,770,662 $ 3.74 Granted 1,348,504 3.08 Vested (1,459,709 ) 4.19 Forfeited (220,559 ) 3.28 Nonvested at December 31, 2015 2,438,898 $ 3.15 Granted 1,302,298 3.36 Vested (813,614 ) 3.25 Forfeited (48,190 ) 3.20 Nonvested at March 31, 2016 2,879,392 $ 3.21
Summary of Restricted Stock Awards Activity (Excluding Salary Shares)	The following table summarizes information about the Corporation’s restricted stock activity for the year ended December 31, 2015 , and for the three months ended March 31, 2016 . Restricted Stock Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2014 1,982,126 $ 15.79 Granted 1,173,847 18.09 Vested (709,582 ) 15.62 Forfeited (196,363 ) 16.87 Outstanding at December 31, 2015 2,250,028 $ 17.03 Granted 1,041,985 16.37 Vested (732,553 ) 16.46 Forfeited (34,299 ) 17.69 Outstanding at March 31, 2016 2,525,161 $ 16.91

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Investment securities available for sale	The amortized cost and fair values of securities available for sale and held to maturity were as follows. March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale: U. S. Treasury securities $ 1,000 $ — $ — $ 1,000 Residential mortgage-related securities: FNMA / FHLMC 1,268,929 35,321 (846 ) 1,303,404 GNMA 1,536,248 11,086 (79 ) 1,547,255 Private-label 1,535 — (23 ) 1,512 GNMA commercial mortgage-related securities 2,053,540 5,855 (11,530 ) 2,047,865 Other securities (debt and equity) 4,718 87 — 4,805 Total investment securities available for sale $ 4,865,970 $ 52,349 $ (12,478 ) $ 4,905,841 Investment securities held to maturity: Obligations of state and political subdivisions (municipal securities) $ 1,054,757 $ 25,972 $ (146 ) $ 1,080,583 Residential mortgage-related securities: FNMA / FHLMC 40,404 797 (180 ) 41,021 GNMA 81,660 1,086 (5 ) 82,741 Total investment securities held to maturity $ 1,176,821 $ 27,855 $ (331 ) $ 1,204,345 December 31, 2015 Amortized Gross Gross Fair Value ($ in Thousands) Investment securities available for sale: U. S. Treasury securities $ 999 $ — $ (2 ) $ 997 Residential mortgage-related securities: FNMA / FHLMC 1,388,995 33,791 (8,160 ) 1,414,626 GNMA 1,605,956 507 (16,460 ) 1,590,003 Private-label 1,722 1 (14 ) 1,709 GNMA commercial mortgage-related securities 1,982,477 1,334 (28,501 ) 1,955,310 Other securities (debt and equity) 4,718 51 — 4,769 Total investment securities available for sale $ 4,984,867 $ 35,684 $ (53,137 ) $ 4,967,414 Investment securities held to maturity: Municipal securities $ 1,043,767 $ 16,803 $ (339 ) $ 1,060,231 Residential mortgage-related securities: FNMA / FHLMC 41,469 513 (645 ) 41,337 GNMA 82,994 189 (309 ) 82,874 Total investment securities held to maturity $ 1,168,230 $ 17,505 $ (1,293 ) $ 1,184,442
Investment securities held to maturity	The amortized cost and fair values of securities available for sale and held to maturity were as follows. March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale: U. S. Treasury securities $ 1,000 $ — $ — $ 1,000 Residential mortgage-related securities: FNMA / FHLMC 1,268,929 35,321 (846 ) 1,303,404 GNMA 1,536,248 11,086 (79 ) 1,547,255 Private-label 1,535 — (23 ) 1,512 GNMA commercial mortgage-related securities 2,053,540 5,855 (11,530 ) 2,047,865 Other securities (debt and equity) 4,718 87 — 4,805 Total investment securities available for sale $ 4,865,970 $ 52,349 $ (12,478 ) $ 4,905,841 Investment securities held to maturity: Obligations of state and political subdivisions (municipal securities) $ 1,054,757 $ 25,972 $ (146 ) $ 1,080,583 Residential mortgage-related securities: FNMA / FHLMC 40,404 797 (180 ) 41,021 GNMA 81,660 1,086 (5 ) 82,741 Total investment securities held to maturity $ 1,176,821 $ 27,855 $ (331 ) $ 1,204,345 December 31, 2015 Amortized Gross Gross Fair Value ($ in Thousands) Investment securities available for sale: U. S. Treasury securities $ 999 $ — $ (2 ) $ 997 Residential mortgage-related securities: FNMA / FHLMC 1,388,995 33,791 (8,160 ) 1,414,626 GNMA 1,605,956 507 (16,460 ) 1,590,003 Private-label 1,722 1 (14 ) 1,709 GNMA commercial mortgage-related securities 1,982,477 1,334 (28,501 ) 1,955,310 Other securities (debt and equity) 4,718 51 — 4,769 Total investment securities available for sale $ 4,984,867 $ 35,684 $ (53,137 ) $ 4,967,414 Investment securities held to maturity: Municipal securities $ 1,043,767 $ 16,803 $ (339 ) $ 1,060,231 Residential mortgage-related securities: FNMA / FHLMC 41,469 513 (645 ) 41,337 GNMA 82,994 189 (309 ) 82,874 Total investment securities held to maturity $ 1,168,230 $ 17,505 $ (1,293 ) $ 1,184,442
Amortized cost and fair values of investment securities available for sale by contractual maturity	The amortized cost and fair values of investment securities available for sale and held to maturity at March 31, 2016 , are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Available for Sale Held to Maturity ($ in Thousands) Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 2,500 $ 2,530 $ 46,749 $ 32,151 Due after one year through five years 3,200 3,200 243,423 255,338 Due after five years through ten years — — 245,683 255,755 Due after ten years — — 518,902 537,339 Total debt securities 5,700 5,730 1,054,757 1,080,583 Residential mortgage-related securities: FNMA / FHLMC 1,268,929 1,303,404 40,404 41,021 GNMA 1,536,248 1,547,255 81,660 82,741 Private-label 1,535 1,512 — — GNMA commercial mortgage-related securities 2,053,540 2,047,865 — — Equity securities 18 75 — — Total investment securities $ 4,865,970 $ 4,905,841 $ 1,176,821 $ 1,204,345 Ratio of Fair Value to Amortized Cost 100.8 % 102.3 %
Realized gains and losses and proceeds from sale	During the first three months of 2016, the Corporation continued to restructure its investment securities portfolio and sold approximately $119 million of FNMA and FHLMC mortgage-related securities and reinvested into GNMA mortgage-related securities, generating a $3 million net gain on sale. This restructuring lowered risk weighted assets and related capital requirements. Three Months Ended March 31, 2016 2015 ($ in Thousands) Gross gains $ 3,287 $ — Gross losses (189 ) — Investment securities gains, net $ 3,098 $ — Proceeds from sales of investment securities $ 119,379 $ 289
Unrealized losses and fair value of available for sale and held to maturity securities, by investment category and time length	The following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position, at March 31, 2016 . Less than 12 months 12 months or more Total March 31, 2016 Number of Securities Unrealized Losses Fair Value Number of Securities Unrealized Losses Fair Value Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale: Residential mortgage-related securities: FNMA / FHLMC — $ — $ — 12 $ (846 ) $ 258,670 $ (846 ) $ 258,670 GNMA 2 (79 ) 41,913 — — — (79 ) 41,913 Private-label 1 (1 ) 76 3 (22 ) 1,382 (23 ) 1,458 GNMA commercial mortgage-related securities 20 (1,390 ) 558,620 21 (10,140 ) 448,861 (11,530 ) 1,007,481 Total 23 $ (1,470 ) $ 600,609 36 $ (11,008 ) $ 708,913 $ (12,478 ) $ 1,309,522 Investment securities held to maturity: Municipal securities 20 $ (75 ) $ 10,029 17 $ (71 ) $ 5,599 $ (146 ) $ 15,628 Residential mortgage-related securities: FNMA / FHLMC 1 (3 ) 1,180 5 (177 ) 13,587 (180 ) 14,767 GNMA — — — 1 (5 ) 1,548 (5 ) 1,548 Total 21 $ (78 ) $ 11,209 23 $ (253 ) $ 20,734 $ (331 ) $ 31,943 For comparative purposes, the following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2015 . Less than 12 months 12 months or more Total December 31, 2015 Number Unrealized Fair Number Unrealized Fair Unrealized Fair ($ in Thousands) Investment securities available for sale: U.S. Treasury securities 1 $ (2 ) $ 997 — $ — $ — $ (2 ) $ 997 Residential mortgage-related securities: FNMA / FHLMC 17 (1,548 ) 220,852 14 (6,612 ) 338,186 (8,160 ) 559,038 GNMA 46 (16,460 ) 1,434,484 — — — (16,460 ) 1,434,484 Private-label 1 (1 ) 83 3 (13 ) 1,565 (14 ) 1,648 GNMA commercial mortgage-related securities 40 (9,610 ) 1,132,844 21 (18,891 ) 448,218 (28,501 ) 1,581,062 Total 105 $ (27,621 ) $ 2,789,260 38 $ (25,516 ) $ 787,969 $ (53,137 ) $ 3,577,229 Investment securities held to maturity: Municipal securities 53 $ (146 ) $ 23,137 24 $ (193 ) $ 9,254 $ (339 ) $ 32,391 Residential mortgage-related securities: FNMA / FHLMC 10 (177 ) 12,754 3 (468 ) 11,106 (645 ) 23,860 GNMA 21 (201 ) 45,499 3 (108 ) 6,797 (309 ) 52,296 Total 84 $ (524 ) $ 81,390 30 $ (769 ) $ 27,157 $ (1,293 ) $ 108,547

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2016
Receivables [Abstract]
Loan composition	The period end loan composition was as follows. March 31, December 31, ($ in Thousands) Commercial and industrial $ 6,511,648 $ 6,190,683 Commercial real estate — owner occupied 917,285 918,212 Commercial and business lending 7,428,933 7,108,895 Commercial real estate — investor 3,276,733 3,234,266 Real estate construction 1,184,398 1,162,145 Commercial real estate lending 4,461,131 4,396,411 Total commercial 11,890,064 11,505,306 Residential mortgage 5,944,457 5,783,267 Home equity 982,994 1,005,802 Other consumer 409,725 419,968 Total consumer 7,337,176 7,209,037 Total loans $ 19,227,240 $ 18,714,343
Commercial and Consumer loans by credit quality indicator	The following table presents commercial and consumer loans by credit quality indicator at March 31, 2016 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 5,713,979 $ 272,090 $ 328,464 $ 197,115 $ 6,511,648 Commercial real estate - owner occupied 834,879 31,856 41,107 9,443 917,285 Commercial and business lending 6,548,858 303,946 369,571 206,558 7,428,933 Commercial real estate - investor 3,208,338 30,680 25,385 12,330 3,276,733 Real estate construction 1,180,914 222 2,422 840 1,184,398 Commercial real estate lending 4,389,252 30,902 27,807 13,170 4,461,131 Total commercial 10,938,110 334,848 397,378 219,728 11,890,064 Residential mortgage 5,883,743 5,014 3,488 52,212 5,944,457 Home equity 967,267 1,446 209 14,072 982,994 Other consumer 408,819 523 — 383 409,725 Total consumer 7,259,829 6,983 3,697 66,667 7,337,176 Total $ 18,197,939 $ 341,831 $ 401,075 $ 286,395 $ 19,227,240 The following table presents commercial and consumer loans by credit quality indicator at December 31, 2015 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 5,522,809 $ 341,169 $ 233,130 $ 93,575 $ 6,190,683 Commercial real estate - owner occupied 835,572 38,885 35,706 8,049 918,212 Commercial and business lending 6,358,381 380,054 268,836 101,624 7,108,895 Commercial real estate - investor 3,153,703 45,976 25,944 8,643 3,234,266 Real estate construction 1,157,034 252 3,919 940 1,162,145 Commercial real estate lending 4,310,737 46,228 29,863 9,583 4,396,411 Total commercial 10,669,118 426,282 298,699 111,207 11,505,306 Residential mortgage 5,727,437 1,552 2,796 51,482 5,783,267 Home equity 988,574 1,762 222 15,244 1,005,802 Other consumer 419,087 556 — 325 419,968 Total consumer 7,135,098 3,870 3,018 67,051 7,209,037 Total $ 17,804,216 $ 430,152 $ 301,717 $ 178,258 $ 18,714,343
Summarized details of Loans	The following table presents loans by past due status at March 31, 2016 . Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due (a) Nonaccrual (b) Total ($ in Thousands) Commercial and industrial $ 6,311,415 $ 2,665 $ 236 $ 217 $ 197,115 $ 6,511,648 Commercial real estate - owner occupied 907,322 520 — — 9,443 917,285 Commercial and business lending 7,218,737 3,185 236 217 206,558 7,428,933 Commercial real estate - investor 3,263,331 748 324 — 12,330 3,276,733 Real estate construction 1,183,143 415 — — 840 1,184,398 Commercial real estate lending 4,446,474 1,163 324 — 13,170 4,461,131 Total commercial 11,665,211 4,348 560 217 219,728 11,890,064 Residential mortgage 5,888,651 3,199 395 — 52,212 5,944,457 Home equity 963,118 4,410 1,394 — 14,072 982,994 Other consumer 406,248 1,020 662 1,412 383 409,725 Total consumer 7,258,017 8,629 2,451 1,412 66,667 7,337,176 Total $ 18,923,228 $ 12,977 $ 3,011 $ 1,629 $ 286,395 $ 19,227,240 (a) The recorded investment in loans past due 90 days or more and still accruing totaled $2 million at March 31, 2016 (the same as the reported balances for the accruing loans noted above). (b) Of the total nonaccrual loans, $230 million or 80% were current with respect to payment at March 31, 2016 . The following table presents loans by past due status at December 31, 2015 . Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due (a) Nonaccrual (b) Total ($ in Thousands) Commercial and industrial $ 6,095,848 $ 602 $ 409 $ 249 $ 93,575 $ 6,190,683 Commercial real estate - owner occupied 903,021 7,142 — — 8,049 918,212 Commercial and business lending 6,998,869 7,744 409 249 101,624 7,108,895 Commercial real estate - investor 3,225,332 291 — — 8,643 3,234,266 Real estate construction 1,160,909 270 26 — 940 1,162,145 Commercial real estate lending 4,386,241 561 26 — 9,583 4,396,411 Total commercial 11,385,110 8,305 435 249 111,207 11,505,306 Residential mortgage 5,726,855 4,491 439 — 51,482 5,783,267 Home equity 982,639 6,190 1,729 — 15,244 1,005,802 Other consumer 416,374 1,195 675 1,399 325 419,968 Total consumer 7,125,868 11,876 2,843 1,399 67,051 7,209,037 Total $ 18,510,978 $ 20,181 $ 3,278 $ 1,648 $ 178,258 $ 18,714,343 (a) The recorded investment in loans past due 90 days or more and still accruing totaled $2 million at December 31, 2015 (the same as the reported balances for the accruing loans noted above). (b) Of the total nonaccrual loans, $124 million or 69% were current with respect to payment at December 31, 2015 .
Summarized details of impaired Loans	The following table presents impaired loans at March 31, 2016 . Recorded Unpaid Related Average Interest ($ in Thousands) Loans with a related allowance Commercial and industrial $ 105,780 $ 106,837 $ 14,595 $ 106,280 $ 613 Commercial real estate — owner occupied 10,477 10,596 554 10,552 89 Commercial and business lending 116,257 117,433 15,149 116,832 702 Commercial real estate — investor 23,494 24,430 1,244 23,541 461 Real estate construction 1,226 1,812 412 1,237 14 Commercial real estate lending 24,720 26,242 1,656 24,778 475 Total commercial 140,977 143,675 16,805 141,610 1,177 Residential mortgage 65,281 70,624 12,351 65,819 548 Home equity 20,337 22,451 9,732 20,504 248 Other consumer 1,276 1,332 221 1,291 8 Total consumer 86,894 94,407 22,304 87,614 804 Total loans (a) $ 227,871 $ 238,082 $ 39,109 $ 229,224 $ 1,981 Loans with no related allowance Commercial and industrial $ 120,243 $ 130,935 $ — $ 120,399 $ 91 Commercial real estate — owner occupied 6,659 9,005 — 6,715 — Commercial and business lending 126,902 139,940 — 127,114 91 Commercial real estate — investor 9,829 9,984 — 9,855 — Real estate construction — — — — — Commercial real estate lending 9,829 9,984 — 9,855 — Total commercial 136,731 149,924 — 136,969 91 Residential mortgage 6,738 7,020 — 6,841 35 Home equity 652 652 — 653 10 Other consumer — — — — — Total consumer 7,390 7,672 — 7,494 45 Total loans (a) $ 144,121 $ 157,596 $ — $ 144,463 $ 136 Total Commercial and industrial $ 226,023 $ 237,772 $ 14,595 $ 226,679 $ 704 Commercial real estate — owner occupied 17,136 19,601 554 17,267 89 Commercial and business lending 243,159 257,373 15,149 243,946 793 Commercial real estate — investor 33,323 34,414 1,244 33,396 461 Real estate construction 1,226 1,812 412 1,237 14 Commercial real estate lending 34,549 36,226 1,656 34,633 475 Total commercial 277,708 293,599 16,805 278,579 1,268 Residential mortgage 72,019 77,644 12,351 72,660 583 Home equity 20,989 23,103 9,732 21,157 258 Other consumer 1,276 1,332 221 1,291 8 Total consumer 94,284 102,079 22,304 95,108 849 Total loans (a) $ 371,992 $ 395,678 $ 39,109 $ 373,687 $ 2,117 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 84% of the unpaid principal balance at March 31, 2016 . The following table presents impaired loans at December 31, 2015 . Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized ($ in Thousands) Loans with a related allowance Commercial and industrial $ 57,785 $ 59,409 $ 8,162 $ 46,833 $ 855 Commercial real estate — owner occupied 9,705 9,804 448 10,087 412 Commercial and business lending 67,490 69,213 8,610 56,920 1,267 Commercial real estate — investor 27,822 29,444 1,831 28,278 1,914 Real estate construction 1,450 2,154 453 1,667 66 Commercial real estate lending 29,272 31,598 2,284 29,945 1,980 Total commercial 96,762 100,811 10,894 86,865 3,247 Residential mortgage 66,590 71,084 12,462 68,183 2,374 Home equity 21,769 23,989 10,118 22,624 1,147 Other consumer 1,154 1,225 195 1,199 30 Total consumer 89,513 96,298 22,775 92,006 3,551 Total loans (a) $ 186,275 $ 197,109 $ 33,669 $ 178,871 $ 6,798 Loans with no related allowance Commercial and industrial $ 65,083 $ 72,259 $ — $ 79,573 $ 1,657 Commercial real estate — owner occupied 6,221 6,648 — 6,534 15 Commercial and business lending 71,304 78,907 — 86,107 1,672 Commercial real estate — investor 2,736 2,840 — 2,763 90 Real estate construction — — — — — Commercial real estate lending 2,736 2,840 — 2,763 90 Total commercial 74,040 81,747 — 88,870 1,762 Residential mortgage 4,762 5,033 — 4,726 126 Home equity 544 544 — 544 30 Other consumer — — — — — Total consumer 5,306 5,577 — 5,270 156 Total loans (a) $ 79,346 $ 87,324 $ — $ 94,140 $ 1,918 Total Commercial and industrial $ 122,868 $ 131,668 $ 8,162 $ 126,406 $ 2,512 Commercial real estate — owner occupied 15,926 16,452 448 16,621 427 Commercial and business lending 138,794 148,120 8,610 143,027 2,939 Commercial real estate — investor 30,558 32,284 1,831 31,041 2,004 Real estate construction 1,450 2,154 453 1,667 66 Commercial real estate lending 32,008 34,438 2,284 32,708 2,070 Total commercial 170,802 182,558 10,894 175,735 5,009 Residential mortgage 71,352 76,117 12,462 72,909 2,500 Home equity 22,313 24,533 10,118 23,168 1,177 Other consumer 1,154 1,225 195 1,199 30 Total consumer 94,819 101,875 22,775 97,276 3,707 Total loans (a) $ 265,621 $ 284,433 $ 33,669 $ 273,011 $ 8,716 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 82% of the unpaid principal balance at December 31, 2015 .
Nonaccrual and Performing Restructured Loans	The following table presents nonaccrual and performing restructured loans by loan portfolio. March 31, 2016 December 31, 2015 Performing Restructured Loans Nonaccrual Restructured Loans (a) Performing Restructured Loans Nonaccrual Restructured Loans (a) ($ in Thousands) Commercial and industrial $ 28,908 $ 2,711 $ 29,293 $ 1,714 Commercial real estate — owner occupied 7,693 2,689 7,877 2,703 Commercial real estate — investor 20,993 1,356 21,915 3,936 Real estate construction 386 182 510 177 Residential mortgage 19,807 23,845 19,870 24,592 Home equity 6,917 4,416 7,069 4,522 Other consumer 893 33 829 40 Total $ 85,597 $ 35,232 $ 87,363 $ 37,684 (a) Nonaccrual restructured loans have been included within nonaccrual loans.
Summary of Restructured Loans	The following table provides the number of loans modified in a troubled debt restructuring by loan portfolio during the three months ended March 31, 2016 and 2015 , respectively, and the recorded investment and unpaid principal balance as of March 31, 2016 and 2015 respectively. Three Months Ended March 31, 2016 Three Months Ended March 31, 2015 Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) ($ in Thousands) Commercial and industrial 7 $ 1,483 $ 1,522 2 $ 196 $ 208 Commercial real estate — owner occupied 1 125 130 5 3,585 3,641 Commercial real estate — investor — — — 4 3,030 3,042 Real estate construction 1 10 55 — — — Residential mortgage 30 2,062 2,124 30 2,816 2,864 Home equity 20 818 879 36 1,782 1,843 Total 59 $ 4,498 $ 4,710 77 $ 11,409 $ 11,598 (a) Represents post-modification outstanding recorded investment. (b) Represents pre-modification outstanding recorded investment.
Troubled debt restructurings subsequent redefault	The following table provides the number of loans modified in a troubled debt restructuring during the previous twelve months which subsequently defaulted during the three months ended March 31, 2016 and 2015 , respectively, as well as the recorded investment in these restructured loans as of March 31, 2016 and 2015 respectively. Three Months Ended March 31, 2016 Three Month Ended March 31, 2015 Number of Loans Recorded Investment Number of Loans Recorded Investment ($ in Thousands) Commercial real estate — owner occupied — $ — 1 $ 297 Real estate construction 1 10 — — Residential mortgage 7 1,151 16 1,239 Home equity 8 153 24 855 Total 16 $ 1,314 41 $ 2,391
Changes in the allowance for loan losses by portfolio segment	A summary of the changes in the allowance for loan losses by portfolio segment for the three months ended March 31, 2016 , was as follows. $ in Thousands Commercial and industrial Commercial real estate - owner occupied Commercial real estate - investor Real estate construction Residential mortgage Home equity Other consumer Total December 31, 2015 $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Charge offs (16,894 ) (76 ) (176 ) (54 ) (1,390 ) (1,746 ) (909 ) (21,245 ) Recoveries 1,958 33 1,415 26 158 600 161 4,351 Net charge offs (14,936 ) (43 ) 1,239 (28 ) (1,232 ) (1,146 ) (748 ) (16,894 ) Provision for loan losses 24,470 (2,059 ) (2,233 ) (3,498 ) 2,030 721 569 20,000 March 31, 2016 $ 139,493 $ 16,578 $ 42,024 $ 21,740 $ 29,059 $ 23,130 $ 5,346 $ 277,370 Allowance for loan losses: Individually evaluated for impairment $ 14,005 $ 74 $ — $ — $ 14 $ — $ — $ 14,093 Collectively evaluated for impairment 125,488 16,504 42,024 21,740 29,045 23,130 5,346 263,277 Total allowance for loan losses $ 139,493 $ 16,578 $ 42,024 $ 21,740 $ 29,059 $ 23,130 $ 5,346 $ 277,370 Loans: Individually evaluated for impairment $ 195,341 $ 7,500 $ 9,829 $ — $ 7,472 $ 652 $ — $ 220,794 Collectively evaluated for impairment 6,316,307 909,785 3,266,904 1,184,398 5,936,985 982,342 409,725 19,006,446 Total loans $ 6,511,648 $ 917,285 $ 3,276,733 $ 1,184,398 $ 5,944,457 $ 982,994 $ 409,725 $ 19,227,240 For comparison purposes, a summary of the changes in the allowance for loan losses by portfolio segment for the year ended December 31, 2015 , was as follows. $ in Thousands Commercial and industrial Commercial real estate - owner occupied Commercial real estate - investor Real estate construction Residential mortgage Home equity Other consumer Total December 31, 2014 $ 117,635 $ 16,510 $ 46,333 $ 20,999 $ 31,926 $ 26,464 $ 6,435 $ 266,302 Charge offs (27,687 ) (2,645 ) (4,645 ) (750 ) (5,636 ) (7,048 ) (3,869 ) (52,280 ) Recoveries 9,821 921 4,157 2,268 1,077 3,233 765 22,242 Net charge offs (17,866 ) (1,724 ) (488 ) 1,518 (4,559 ) (3,815 ) (3,104 ) (30,038 ) Provision for loan losses 30,190 3,894 (2,827 ) 2,749 894 906 2,194 38,000 December 31, 2015 $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Allowance for loan losses: Individually evaluated for impairment $ 7,522 $ — $ 229 $ — $ 166 $ 46 $ — $ 7,963 Collectively evaluated for impairment 122,437 18,680 42,789 25,266 28,095 23,509 5,525 266,301 Total allowance for loan losses $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Loans: Individually evaluated for impairment $ 91,569 $ 6,221 $ 5,460 $ — $ 6,956 $ 1,281 $ — $ 111,487 Collectively evaluated for impairment 6,099,114 911,991 3,228,806 1,162,145 5,776,311 1,004,521 419,968 18,602,856 Total loans $ 6,190,683 $ 918,212 $ 3,234,266 $ 1,162,145 $ 5,783,267 $ 1,005,802 $ 419,968 $ 18,714,343
Changes in the allowance for unfunded commitments	A summary of the changes in the allowance for unfunded commitments was as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Allowance for Unfunded Commitments: Balance at beginning of period $ 24,400 $ 24,900 Provision for unfunded commitments — (500 ) Balance at end of period $ 24,400 $ 24,400

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	Goodwill and Other Intangible Assets Goodwill: Goodwill is not amortized but, instead, is subject to impairment tests on at least an annual basis, and more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The impairment testing process is conducted by assigning net assets and goodwill to each reporting unit. An initial qualitative evaluation is made to assess the likelihood of impairment and determine whether further quantitative testing to calculate the fair value is necessary. When the qualitative evaluation indicates that impairment is more likely than not, quantitative testing is required whereby the fair value of each reporting unit is calculated and compared to the recorded book value, “step one.” If the calculated fair value of the reporting unit exceeds its carrying value, goodwill is not considered impaired and “step two” is not considered necessary. If the carrying value of a reporting unit exceeds its calculated fair value, the impairment test continues (“step two”) by comparing the carrying value of the reporting unit’s goodwill to the implied fair value of goodwill. The implied fair value is computed by adjusting all assets and liabilities of the reporting unit to current fair value with the offset adjustment to goodwill. The adjusted goodwill balance is the implied fair value of the goodwill. An impairment charge is recognized if the carrying value of goodwill exceeds the implied fair value of goodwill. The Corporation conducted its most recent annual impairment testing in May 2015, utilizing a qualitative assessment. Factors that management considered in this assessment included macroeconomic conditions, industry and market considerations, overall financial performance of the Corporation and each reporting unit (both current and projected), changes in management strategy, and changes in the composition or carrying amount of net assets. In addition, management considered the changes in both the Corporation’s common stock price and in the overall bank common stock index (based on the S&P 400 Regional Bank Sub-Industry Index), as well as the Corporation’s earnings per common share trend over the past year. Based on these assessments, management concluded that the 2015 annual qualitative impairment assessment indicated that it is more likely than not that the estimated fair value exceeded the carrying value (including goodwill) for each reporting unit. Therefore, a step one quantitative analysis was not required. There were no events since the May 2015 impairment testing that have changed the Corporation's impairment assessment conclusion. There were no impairment charges recorded in 2015 or the first three months of 2016. At March 31, 2016 , the Corporation had goodwill of $972 million , compared to $969 million at December 31, 2015 . Goodwill increased by approximately $3 million during the first quarter of 2016 as a result of two small insurance acquisitions. See Note 2 for additional information on the Corporation's acquisitions. Other Intangible Assets: The Corporation has other intangible assets that are amortized, consisting of core deposit intangibles, other intangibles (primarily related to customer relationships acquired in connection with the Corporation’s insurance agency acquisitions), and mortgage servicing rights. Core deposit intangibles of approximately $15 million were fully amortized in 2015 and have been removed from both the gross carrying amount and the accumulated amortization for 2016. Other intangibles increased by approximately $1 million during the first quarter of 2016 for the customer relationships associated with two small insurance acquisitions. See Note 2 for additional information on the Corporation's acquisitions. For core deposit intangibles and other intangibles, changes in the gross carrying amount, accumulated amortization, and net book value were as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Core deposit intangibles: Gross carrying amount $ 4,385 $ 19,545 Accumulated amortization (4,062 ) (19,152 ) Net book value $ 323 $ 393 Amortization during the year $ 70 $ 1,404 Other intangibles: Gross carrying amount $ 32,410 $ 31,398 Accumulated amortization (15,767 ) (15,333 ) Net book value $ 16,643 $ 16,065 Additions during the period $ 1,012 $ 12,115 Amortization during the year $ 434 $ 1,690 The Corporation sells residential mortgage loans in the secondary market and typically retains the right to service the loans sold. Mortgage servicing rights are amortized in proportion to and over the period of estimated net servicing income, and assessed for impairment at each reporting date. The Corporation periodically evaluates its mortgage servicing rights asset for impairment. Impairment is assessed based on fair value at each reporting date using estimated prepayment speeds of the underlying mortgage loans serviced and stratifications based on the risk characteristics of the underlying loans (predominantly loan type and note interest rate). As mortgage interest rates fall, prepayment speeds are usually faster and the value of the mortgage servicing rights asset generally decreases, requiring additional valuation reserve. Conversely, as mortgage interest rates rise, prepayment speeds are usually slower and the value of the mortgage servicing rights asset generally increases, requiring less valuation reserve. A valuation allowance is established, through a charge to earnings, to the extent the amortized cost of the mortgage servicing rights exceeds the estimated fair value by stratification. If it is later determined that all or a portion of the temporary impairment no longer exists for a stratification, the valuation is reduced through a recovery to earnings. An other-than-temporary impairment (i.e., recoverability is considered remote when considering interest rates and loan pay off activity) is recognized as a write-down of the mortgage servicing rights asset and the related valuation allowance (to the extent a valuation allowance is available) and then against earnings. A direct write-down permanently reduces the carrying value of the mortgage servicing rights asset and valuation allowance, precluding subsequent recoveries. See Note 12 for a discussion of the recourse provisions on sold residential mortgage loans. See Note 13 which further discusses fair value measurement relative to the mortgage servicing rights asset. A summary of changes in the balance of the mortgage servicing rights asset and the mortgage servicing rights valuation allowance was as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Mortgage servicing rights Mortgage servicing rights at beginning of period $ 62,150 $ 61,379 Additions 1,856 12,372 Amortization (2,874 ) (11,601 ) Mortgage servicing rights at end of period $ 61,132 $ 62,150 Valuation allowance at beginning of period (809 ) (1,234 ) (Additions) recoveries, net (909 ) 425 Valuation allowance at end of period (1,718 ) (809 ) Mortgage servicing rights, net $ 59,414 $ 61,341 Fair value of mortgage servicing rights $ 61,410 $ 70,686 Portfolio of residential mortgage loans serviced for others (“servicing portfolio”) $ 7,876,888 $ 7,915,224 Mortgage servicing rights, net to servicing portfolio 0.75 % 0.77 % Mortgage servicing rights expense (1) $ 3,783 $ 11,176 (1) Includes the amortization of mortgage servicing rights and additions / recoveries to the valuation allowance of mortgage servicing rights, and is a component of mortgage banking, net in the consolidated statements of income. The following table shows the estimated future amortization expense for amortizing intangible assets. The projections of amortization expense are based on existing asset balances, the current interest rate environment, and prepayment speeds as of March 31, 2016 . The actual amortization expense the Corporation recognizes in any given period may be significantly different depending upon acquisition or sale activities, changes in interest rates, prepayment speeds, market conditions, regulatory requirements, and events or circumstances that indicate the carrying amount of an asset may not be recoverable. Estimated Amortization Expense Core Deposit Intangibles Other Intangibles Mortgage Servicing Rights ($ in Thousands) Nine months ending December 31, 2016 $ 211 $ 1,378 $ 8,850 2017 112 1,786 9,674 2018 — 1,756 7,761 2019 — 1,457 6,313 2020 — 1,340 5,169 2021 — 1,316 4,265 Beyond 2021 — 7,610 19,100 Total Estimated Amortization Expense $ 323 $ 16,643 $ 61,132
Summary of core deposit intangibles and other intangibles	For core deposit intangibles and other intangibles, changes in the gross carrying amount, accumulated amortization, and net book value were as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Core deposit intangibles: Gross carrying amount $ 4,385 $ 19,545 Accumulated amortization (4,062 ) (19,152 ) Net book value $ 323 $ 393 Amortization during the year $ 70 $ 1,404 Other intangibles: Gross carrying amount $ 32,410 $ 31,398 Accumulated amortization (15,767 ) (15,333 ) Net book value $ 16,643 $ 16,065 Additions during the period $ 1,012 $ 12,115 Amortization during the year $ 434 $ 1,690
Summary of changes in balance of mortgage servicing rights asset and mortgage servicing rights valuation allowance	A summary of changes in the balance of the mortgage servicing rights asset and the mortgage servicing rights valuation allowance was as follows. Three Months Ended March 31, 2016 Year Ended December 31, 2015 ($ in Thousands) Mortgage servicing rights Mortgage servicing rights at beginning of period $ 62,150 $ 61,379 Additions 1,856 12,372 Amortization (2,874 ) (11,601 ) Mortgage servicing rights at end of period $ 61,132 $ 62,150 Valuation allowance at beginning of period (809 ) (1,234 ) (Additions) recoveries, net (909 ) 425 Valuation allowance at end of period (1,718 ) (809 ) Mortgage servicing rights, net $ 59,414 $ 61,341 Fair value of mortgage servicing rights $ 61,410 $ 70,686 Portfolio of residential mortgage loans serviced for others (“servicing portfolio”) $ 7,876,888 $ 7,915,224 Mortgage servicing rights, net to servicing portfolio 0.75 % 0.77 % Mortgage servicing rights expense (1) $ 3,783 $ 11,176 (1) Includes the amortization of mortgage servicing rights and additions / recoveries to the valuation allowance of mortgage servicing rights, and is a component of mortgage banking, net in the consolidated statements of income.
Summary of estimated future amortization expense	The following table shows the estimated future amortization expense for amortizing intangible assets. The projections of amortization expense are based on existing asset balances, the current interest rate environment, and prepayment speeds as of March 31, 2016 . The actual amortization expense the Corporation recognizes in any given period may be significantly different depending upon acquisition or sale activities, changes in interest rates, prepayment speeds, market conditions, regulatory requirements, and events or circumstances that indicate the carrying amount of an asset may not be recoverable. Estimated Amortization Expense Core Deposit Intangibles Other Intangibles Mortgage Servicing Rights ($ in Thousands) Nine months ending December 31, 2016 $ 211 $ 1,378 $ 8,850 2017 112 1,786 9,674 2018 — 1,756 7,761 2019 — 1,457 6,313 2020 — 1,340 5,169 2021 — 1,316 4,265 Beyond 2021 — 7,610 19,100 Total Estimated Amortization Expense $ 323 $ 16,643 $ 61,132

Short and Long-Term Funding (Ta

Short and Long-Term Funding (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Breakdown of short & long-term debt balances	The components of short-term funding (funding with original contractual maturities of one year or less) and long-term funding (funding with original contractual maturities greater than one year) were as follows. March 31, 2016 December 31, 2015 ($ in Thousands) Short-Term Funding Federal funds purchased $ 74,985 $ 47,870 Securities sold under agreements to repurchase 508,262 383,568 Federal funds purchased and securities sold under agreements to repurchase $ 583,247 $ 431,438 FHLB advances 770,000 335,000 Commercial paper 64,161 67,978 Other short-term funding 834,161 402,978 Total short-term funding $ 1,417,408 $ 834,416 Long-Term Funding FHLB advances $ 2,365,216 $ 1,750,225 Senior notes, at par 250,000 680,000 Subordinated notes, at par 250,000 250,000 Other long-term funding and capitalized costs (1) (3,900 ) (4,061 ) Total long-term funding 2,861,316 2,676,164 Total short and long-term funding $ 4,278,724 $ 3,510,580 (1) Debt issuance costs are now reflected on the balance sheet with the related debt issued rather than within other assets. See Note 3 for additional information on this new accounting standard.
Remaining contractual maturity of securities sold under agreements to repurchase	Remaining Contractual Maturity of the Agreements March 31, 2016 Overnight and Continuous Up to 30 days 30-90 days Greater than 90 days Total ($ in Thousands) Repurchase agreements GSE securities $ 508,262 $ — $ — $ — $ 508,262 Total $ 508,262 $ — $ — $ — $ 508,262 December 31, 2015 Repurchase agreements GSE securities $ 383,568 $ — $ — $ — $ 383,568 Total $ 383,568 $ — $ — $ — $ 383,568

Derivative and Hedging Activi32

Derivative and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Balance sheet category and fair values of derivative instruments not designated as hedging instruments	The table below identifies the balance sheet category and fair values of the Corporation’s free standing derivative instruments, which are not designated as hedging instruments. March 31, 2016 December 31, 2015 ($ in Thousands) Notional Amount Fair Value Balance Sheet Category Notional Amount Fair Balance Sheet Interest rate-related instruments — customer and mirror $ 1,806,688 $ 47,780 Trading assets $ 1,665,965 $ 29,391 Trading assets Interest rate-related instruments — customer and mirror 1,806,688 (50,145 ) Trading liabilities 1,665,965 (30,886 ) Trading liabilities Interest rate lock commitments (mortgage) 418,136 2,689 Other assets 271,530 958 Other assets Forward commitments (mortgage) 249,866 (1,732 ) Other liabilities 231,798 403 Other assets Foreign currency exchange forwards 124,617 4,203 Trading assets 72,976 1,532 Trading assets Foreign currency exchange forwards 116,751 (4,097 ) Trading liabilities 65,649 (1,398 ) Trading liabilities Commodity contracts 43,646 1,104 Trading assets 44,380 1,269 Trading assets Commodity contracts 43,770 (981 ) Trading liabilities 44,256 (1,146 ) Trading liabilities Purchased options (time deposit) 103,475 2,228 Other assets 104,582 2,715 Other assets Written options (time deposit) 103,475 (2,228 ) Other liabilities 104,582 (2,715 ) Other liabilities
Gain (loss) on derivative instruments not designated as hedging instruments	The table below identifies the income statement category of the gains and losses recognized in income on the Corporation’s derivative instruments not designated as hedging instruments. Income Statement Category of Gain / (Loss) Recognized in Income For the Three Months Ended March 31, ($ in Thousands) 2016 2015 Derivative Instruments: Interest rate-related instruments — customer and mirror, net Capital market fees, net $ (870 ) $ (294 ) Interest rate lock commitments (mortgage) Mortgage banking, net 1,731 1,738 Forward commitments (mortgage) Mortgage banking, net (2,135 ) 640 Foreign currency exchange forwards Capital market fees, net (28 ) 66 Commodity contracts Capital market fees, net — —

Balance Sheet Offsetting (Table

Balance Sheet Offsetting (Tables)	3 Months Ended
	Mar. 31, 2016
Offsetting [Abstract]
Balance Sheet Offsetting of Derivative Assets and Liabilities	The following table presents the assets and liabilities subject to an enforceable master netting arrangement. The interest and commodity agreements we have with our commercial customers are not subject to an enforceable master netting arrangement, and therefore, are excluded from this table. Gross amounts recognized Gross amounts not offset in the balance sheet Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Collateral Net amount ($ in Thousands) March 31, 2016 Derivative assets: Interest and commodity agreements $ 823 $ — $ 823 $ (823 ) $ — $ — Derivative liabilities: Interest and commodity agreements $ 48,700 $ — $ 48,700 $ (823 ) $ (47,877 ) $ — December 31, 2015 Derivative assets: Interest and commodity instruments $ 1,466 $ — $ 1,466 $ (1,466 ) $ — $ — Derivative liabilities: Interest and commodity instruments $ 30,200 $ — $ 30,200 $ (1,466 ) $ (28,734 ) $ —

Commitments, Off-Balance Shee34

Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings (Tables)	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Summary of lending-related and other commitments	The following is a summary of lending-related commitments. March 31, 2016 December 31, 2015 ($ in Thousands) Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale(1)(2) $ 7,315,642 $ 7,402,518 Commercial letters of credit(1) 7,782 9,945 Standby letters of credit(3) 278,740 296,508 1) These off-balance sheet financial instruments are exercisable at the market rate prevailing at the date the underlying transaction will be completed and, thus, are deemed to have no current fair value, or the fair value is based on fees currently charged to enter into similar agreements and is not material at March 31, 2016 or December 31, 2015 . 2) Interest rate lock commitments to originate residential mortgage loans held for sale are considered derivative instruments and are disclosed in Note 10 . 3) The Corporation has established a liability of $3 million at both March 31, 2016 and December 31, 2015 , as an estimate of the fair value of these financial instruments.
Summary of changes in the residential mortgage repurchase reserve	The following summarizes the changes in the mortgage repurchase reserve. For the Three Months Ended March 31, 2016 For the Year Ended December 31, 2015 ($ in Thousands) Balance at beginning of period $ 1,197 $ 3,258 Repurchase provision expense 70 428 Adjustments to provision expense — (2,450 ) Charge offs, net (3 ) (39 ) Balance at end of period $ 1,264 $ 1,197

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured on Recurring Basis at Fair Value	Assets and Liabilities Measured at Fair Value on a Recurring Basis Fair Value Hierarchy March 31, 2016 December 31, 2015 ($ in Thousands) Assets: Investment securities available for sale: U.S. Treasury securities Level 1 $ 1,000 $ 997 Residential mortgage-related securities: FNMA / FHLMC Level 2 1,303,404 1,414,626 GNMA Level 2 1,547,255 1,590,003 Private-label Level 2 1,512 1,709 GNMA commercial mortgage-related securities Level 2 2,047,865 1,955,310 Other securities (debt and equity) Level 1 1,605 1,569 Other securities (debt and equity) Level 2 3,000 3,000 Other securities (debt and equity) Level 3 200 200 Total investment securities available for sale Level 1 2,605 2,566 Total investment securities available for sale Level 2 4,903,036 4,964,648 Total investment securities available for sale Level 3 200 200 Interest rate-related instruments Level 2 47,780 29,391 Foreign currency exchange forwards Level 2 4,203 1,532 Interest rate lock commitments to originate residential mortgage loans held for sale Level 3 2,689 958 Forward commitments to sell residential mortgage loans Level 3 — 403 Commodity contracts Level 2 1,104 1,269 Purchased options (time deposit) Level 2 2,228 2,715 Liabilities: Interest rate-related instruments Level 2 50,145 30,886 Foreign currency exchange forwards Level 2 4,097 1,398 Forward commitments to sell residential mortgage loans Level 3 1,732 — Commodity contracts Level 2 981 1,146 Written options (time deposit) Level 2 2,228 2,715
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)	The table below presents a rollforward of the balance sheet amounts for the three months ended March 31, 2016 and the year ended December 31, 2015 , for financial instruments measured on a recurring basis and classified within Level 3 of the fair value hierarchy. Investment Securities Available for Sale Derivative Financial Instruments ($ in Thousands) Balance December 31, 2014 $ 200 $ (488 ) Total net gains included in income: Mortgage derivative gain — 1,849 Balance December 31, 2015 $ 200 $ 1,361 Total net losses included in income: Mortgage derivative loss — (404 ) Balance March 31, 2016 $ 200 $ 957
Assets and Liabilities Measured on Nonrecurring Basis at Fair Value	The table below presents the Corporation’s loans held for sale, impaired loans, and mortgage servicing rights measured at fair value on a nonrecurring basis as of March 31, 2016 and December 31, 2015 , aggregated by the level in the fair value hierarchy within which those measurements fall. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Income Statement Category of Adjustment Recognized in Income ($ in Thousands) Fair Value Hierarchy Fair Value March 31, 2016 Assets: Loans held for sale (2) Level 2 $ 129,398 Mortgage banking, net $ — Impaired loans (1) Level 3 84,664 Provision for credit losses (15,097 ) Mortgage servicing rights Level 3 61,410 Mortgage banking, net (909 ) December 31, 2015 Assets: Loans held for sale Level 2 $ 124,915 Mortgage banking, net $ (155 ) Impaired loans (1) Level 3 41,891 Provision for credit losses (7,796 ) Mortgage servicing rights Level 3 70,686 Mortgage banking, net 425 (1) Represents individually evaluated impaired loans, net of the related allowance for loan losses. (2) Loans held for sale are carried at the lower of cost or estimated fair value. At March 31, 2016, the estimated fair value exceeded the cost and therefore there was no adjustment recognized in Income.
Estimated fair values of financial instruments	The estimated fair values of the Corporation’s financial instruments were as follows. March 31, 2016 December 31, 2015 Fair Value Hierarchy Level Carrying Amount Fair Value Carrying Amount Fair Value ($ in Thousands) Financial assets: Cash and due from banks Level 1 $ 287,183 $ 287,183 $ 374,921 $ 374,921 Interest-bearing deposits in other financial institutions Level 1 68,025 68,025 79,764 79,764 Federal funds sold and securities purchased under agreements to resell Level 1 20,200 20,200 19,000 19,000 Investment securities held to maturity Level 2 1,176,821 1,204,345 1,168,230 1,184,442 Investment securities available for sale Level 1 2,605 2,605 2,566 2,566 Investment securities available for sale Level 2 4,903,036 4,903,036 4,964,648 4,964,648 Investment securities available for sale Level 3 200 200 200 200 FHLB and Federal Reserve Bank stocks Level 2 181,853 181,853 147,240 147,240 Loans held for sale Level 2 128,339 129,398 124,915 124,915 Loans, net Level 3 18,949,870 19,025,680 18,440,079 18,389,832 Bank owned life insurance Level 2 580,583 580,583 583,019 583,019 Derivatives (trading and other assets) Level 2 55,315 55,315 34,907 34,907 Derivatives (trading and other assets) Level 3 2,689 2,689 1,361 1,361 Financial liabilities: Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts Level 3 $ 19,117,418 $ 19,117,418 $ 19,444,863 $ 19,444,863 Brokered CDs and other time deposits Level 2 1,568,042 1,576,714 1,562,802 1,564,464 Short-term funding Level 2 1,417,408 1,417,408 834,416 834,416 Long-term funding Level 2 2,861,316 2,925,447 2,676,164 2,728,112 Standby letters of credit (1) Level 2 2,746 2,746 2,954 2,954 Derivatives (trading and other liabilities) Level 2 57,451 57,451 36,145 36,145 Derivatives (trading and other liabilities) Level 3 1,732 1,732 — —

Retirement Plans (Tables)

Retirement Plans (Tables)	3 Months Ended
	Mar. 31, 2016
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Net period benefit cost for the pension and postretirement plans	The components of net periodic benefit cost for the RAP and Postretirement Plans for three months ended March 31, 2016 and 2015 were as follows. Three Months Ended March 31, 2016 2015 ($ in Thousands) Components of Net Periodic Benefit Cost Pension Plan: Service cost $ 1,725 $ 3,063 Interest cost 1,780 1,642 Expected return on plan assets (5,065 ) (5,350 ) Amortization of prior service cost 13 13 Amortization of actuarial loss 482 532 Total net pension cost $ (1,065 ) $ (100 ) Postretirement Plan: Interest cost $ 36 $ 35 Total net periodic benefit cost $ 36 $ 35

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Selected segment information	Information about the Corporation’s segments is presented below. Segment Income Statement Data ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Three Months Ended March 31, 2016 Net interest income $ 79,164 $ 85,605 $ 7,218 $ 171,987 Noninterest income 11,613 63,748 7,831 83,192 Total revenue 90,777 149,353 15,049 255,179 Credit provision* 12,739 6,142 1,119 20,000 Noninterest expense 34,403 121,295 18,273 173,971 Income (loss) before income taxes 43,635 21,916 (4,343 ) 61,208 Income tax expense (benefit) 14,579 7,670 (3,575 ) 18,674 Net income (loss) $ 29,056 $ 14,246 $ (768 ) $ 42,534 Return on average allocated capital (ROCET1)** 11.3 % 9.1 % (5.0 )% 8.6 % Three Months Ended March 31, 2015 Net interest income $ 75,691 $ 86,357 $ 5,765 $ 167,813 Noninterest income 12,613 65,344 1,856 79,813 Total revenue 88,304 151,701 7,621 247,626 Credit provision* 9,526 7,071 (12,097 ) 4,500 Noninterest expense 34,460 118,373 21,159 173,992 Income (loss) before income taxes 44,318 26,257 (1,441 ) 69,134 Income tax expense (benefit) 15,368 9,190 (2,096 ) 22,462 Net income $ 28,950 $ 17,067 $ 655 $ 46,672 Return on average allocated capital (ROCET1)** 12.5 % 10.7 % (1.1 )% 10.2 % Segment Balance Sheet Data ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Three Months Ended March 31, 2016 Average earning assets $ 9,720,028 $ 9,120,319 $ 6,432,026 $ 25,272,373 Average loans 9,711,221 9,119,020 92,589 18,922,830 Average deposits 5,918,341 11,100,195 3,556,638 20,575,174 Average allocated capital (CET1)** $ 1,031,659 $ 627,211 $ 237,611 $ 1,896,481 Three Months Ended March 31, 2015 Average earning assets $ 9,218,844 $ 8,525,399 $ 6,403,783 $ 24,148,026 Average loans 9,210,992 8,525,399 78,724 17,815,115 Average deposits 5,421,541 10,522,618 3,111,037 19,055,196 Average allocated capital (CET1)** $ 942,764 $ 647,375 $ 214,078 $ 1,804,217 * The consolidated credit provision is equal to the actual reported provision for credit losses. ** The Federal Reserve establishes capital adequacy requirements for the Corporation, including Tier 1 capital. Tier 1 capital is comprised of common capital and certain redeemable, non-cumulative preferred stock. Average allocated capital represents average common equity Tier 1 which is defined as average Tier 1 capital excluding qualifying perpetual preferred stock and qualifying trust preferred securities. This is a non-GAAP financial measure. For segment reporting purposes, the ROCET1 reflects return on average allocated common equity Tier 1 (“CET1”). The ROCET1 for the Risk Management and Shared Services segment and the Consolidated Total is inclusive of the annualized effect of the preferred stock dividends.

Accumulated Other Comprehensi38

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Summary of activity in accumulated other comprehensive income (loss)	The following table summarizes the components of accumulated other comprehensive income (loss) at March 31, 2016 and 2015 , changes during the three month periods then ended, and reclassifications out of accumulated other comprehensive income (loss) during the three month periods ended March 31, 2016 and 2015 , respectively. ($ in Thousands) Investments Securities Available For Sale Defined Benefit Pension and Post Retirement Obligations Accumulated Other Comprehensive Income (Loss) Balance January 1, 2016 $ 459 $ (33,075 ) $ (32,616 ) Other comprehensive income before reclassifications 60,422 — 60,422 Amounts reclassified from accumulated other comprehensive income (loss): Investment securities gain, net (3,098 ) — (3,098 ) Personnel expense — 495 495 Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities) (1,572 ) — (1,572 ) Income tax expense (21,275 ) (189 ) (21,464 ) Net other comprehensive income during period 34,477 306 34,783 Balance March 31, 2016 $ 34,936 $ (32,769 ) $ 2,167 Balance January 1, 2015 $ 18,512 $ (23,362 ) $ (4,850 ) Other comprehensive income before reclassifications 47,418 — 47,418 Amounts reclassified from accumulated other comprehensive income: Personnel expense — 545 545 Income tax expense (18,105 ) (208 ) (18,313 ) Net other comprehensive income during period 29,313 337 29,650 Balance March 31, 2015 $ 47,825 $ (23,025 ) $ 24,800

Acquisitions (Details)

Acquisitions (Details) - USD ($) $ in Thousands	Feb. 17, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Common stock issued in acquisition		$ 0	$ 43,530
Goodwill acquired during period		3,000
Additions to finite-lived intangible assets		1,000		$ 12,000
Ahmann and Martin Company [Member]
Business Acquisition [Line Items]
Common stock issued in acquisition	$ 48,000
Maximum contingent consideration	$ 8,000
Goodwill acquired during period				40,000
Other Intangible Assets [Member]
Business Acquisition [Line Items]
Additions to finite-lived intangible assets		$ 1,012		$ 12,115

New Accounting Pronouncements40

New Accounting Pronouncements Adopted (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Other Assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (3)
Long-term Debt [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (3)

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Calculations for basic and diluted earnings per common share
Net income	$ 42,534	$ 46,672
Preferred stock dividends	(2,198)	(1,228)
Net income available to common equity	40,336	45,444
Common shareholder dividends	(16,203)	(15,166)
Unvested share-based payment awards	(206)	(114)
Undistributed earnings	23,927	30,164
Undistributed earnings allocated to common shareholders	23,686	29,886
Undistributed earnings allocated to unvested share-based payment awards	241	278
Undistributed earnings	23,927	30,164
Basic
Distributed earnings to common shareholders	16,203	15,166
Undistributed earnings allocated to common shareholders	23,686	29,886
Total common shareholders earnings, basic	39,889	45,052
Diluted
Distributed earnings to common shareholders	16,203	15,166
Undistributed earnings allocated to common shareholders	23,686	29,886
Total common shareholders earnings, diluted	$ 39,889	$ 45,052
Weighted average common shares outstanding (in shares)	148,601	150,070
Effect of dilutive common stock awards (in shares)	853	1,094
Diluted weighted average common shares outstanding (in shares)	149,454	151,164
Basic earnings (loss) per common share (in usd per share)	$ 0.27	$ 0.30
Diluted earnings (loss) per common share (in usd per share)	$ 0.27	$ 0.30
Earnings Per Share (Textuals) [Abstract]
Number of antidilutive stock options excluded from the computation of diluted earnings per share (in shares)	3,000	2,000
Warrants to purchase	4,000	4,000

Stock-Based Compensation, Stock

Stock-Based Compensation, Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair value assumptions of stock options
Dividend yield	2.50%	2.00%
Risk-free interest rate	2.00%	2.00%
Weighted average expected volatility	25.00%	20.00%
Weighted average expected life	5 years 6 months	6 years
Weighted average per share fair value of stock options (in usd per share)	$ 3.36	$ 3.08
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock Options Shares Outstanding, Beginning balance (in shares)	6,629,143	7,847,338
Granted (in shares)	1,302,298	1,348,504
Exercised (in shares)	(96,602)	(1,351,646)
Forfeited or expired (in shares)	(48,190)	(1,215,053)
Stock Options Shares Outstanding, Ending balance (in shares)	7,786,649	6,629,143
Options exercisable (in shares)	4,907,257	4,190,245
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Stock Options Outstanding, Weighted Average Exercise Price, Beginning balance (in usd per share)	$ 17.22	$ 18.34
Granted, Weighted Average Exercise Price (in usd per share)	17.45	17.95
Exercised, Weighted Average Exercise Price (in usd per share)	13.60	13.90
Forfeited or expired, Weighted Average Exercise Price (in usd per share)	17.75	29.13
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance (in usd per share)	17.30	17.22
Options Exercisable, Weighted Average Exercise Price (in usd per share)	$ 17.22	$ 17.25
Stock Options Outstanding, Weighted Average Remaining Contractual Term	6 years 7 months 10 days	6 years 2 months 26 days
Options exercisable, Weighted Average Remaining Contractual Term	5 years 2 months 5 days	4 years 11 months 5 days
Stock Options Outstanding, Aggregate Intrinsic Value	$ 14,682	$ 18,730
Options exercisable, Aggregate Intrinsic Value	$ 12,950	$ 14,873

Stock-Based Compensation, Nonve

Stock-Based Compensation, Nonvested Stock Option Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Summary of nonvested stock activity
Granted (in shares)	1,302,298	1,348,504
Nonvested Stock Options [Member]
Summary of nonvested stock activity
Stock Options Shares Outstanding, Beginning balance (in shares)	2,438,898	2,770,662
Granted (in shares)	1,302,298	1,348,504
Vested (in shares)	(813,614)	(1,459,709)
Forfeited (in shares)	(48,190)	(220,559)
Stock Options Shares Outstanding, Ending balance (in shares)	2,879,392	2,438,898
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Exercise Price [Roll Forward]
Nonvested Weighted Average Grant Date Fair Value, Beginning balance (in usd per share)	$ 3.15	$ 3.74
Granted Weighted Average Grant Date Fair Value (in usd per share)	3.36	3.08
Vested Weighted Average Grant Date Fair Value (in usd per share)	3.25	4.19
Forfeited Weighted Average Grant Date Fair Value (in usd per share)	3.20	3.28
Nonvested Weighted Average Grant Date Fair Value, Ending balance (in usd per share)	$ 3.21	$ 3.15

Stock-Based Compensation, Restr

Stock-Based Compensation, Restricted Stock Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding Shares, Beginning balance (in shares)	2,250,028	1,982,126
Granted (in shares)	1,041,985	1,173,847
Vested (in shares)	(732,553)	(709,582)
Forfeited (in shares)	(34,299)	(196,363)
Outstanding Shares, Ending balance (in shares)	2,525,161	2,250,028
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding, Weighted Average Grant Date Fair Value, Beginning balance (in usd per share)	$ 17.03	$ 15.79
Granted, Weighted Average Grant Date Fair Value (in usd per share)	16.37	18.09
Vested, Weighted Average Grant Date Fair Value (in usd per share)	16.46	15.62
Forfeited, Weighted Average Grant Date Fair Value (in usd per share)	17.69	16.87
Outstanding Weighted Average Grant Date Fair Value, Ending balance (in usd per share)	$ 16.91	$ 17.03

Stock-Based Compensation (Detai

Stock-Based Compensation (Details Textuals) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 7 months 10 days	6 years 2 months 26 days
Unvested share-based payment awards	$ 8,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	5 years 2 months 5 days	4 years 11 months 5 days
Stock Based Compensation (Textuals) [Abstract]
Intrinsic value of stock options exercised	$ 420	$ 7,000
Total fair value of vested stock options	$ 3,000	$ 6,000
Service-based Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years	4 years
Performance-based Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years	3 years
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense for accelerated vesting of stock options	$ 857
Recognized compensation expense for vesting of stock options	$ 1,000	$ 4,000
Total compensation cost not yet recognized, period for recognition	fourth quarter 2019
Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense for accelerated vesting of stock options	$ 2,000
Recognized compensation expense for vesting of stock options	7,000	$ 15,000
Unvested share-based payment awards	$ 33,000
Total compensation cost not yet recognized, period for recognition	fourth quarter 2019
2013 Incentive Compensation Plan [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term of awards	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
2013 Incentive Compensation Plan [Member] | Service-based Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of transfer restrictions	4 years
2013 Incentive Compensation Plan [Member] | Performance-based Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of transfer restrictions	3 years

Investment Securities, AFS and

Investment Securities, AFS and HTM Securities Amortized Costs and Fair Values (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investment securities available for sale:
Amortized Cost	$ 4,865,970	$ 4,984,867
Gross Unrealized Gains	52,349	35,684
Gross Unrealized Losses	(12,478)	(53,137)
Fair Value	4,905,841	4,967,414
Investment securities held to maturity:
Amortized Cost	1,176,821	1,168,230
Gross Unrealized Gains	27,855	17,505
Gross Unrealized Losses	(331)	(1,293)
Fair Value	1,204,345	1,184,442
US Treasury Securities [Member]
Investment securities available for sale:
Amortized Cost	1,000	999
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(2)
Fair Value	1,000	997
Obligations of state and political subdivisions (municipal securities) [Member]
Investment securities held to maturity:
Amortized Cost	1,054,757	1,043,767
Gross Unrealized Gains	25,972	16,803
Gross Unrealized Losses	(146)	(339)
Fair Value	1,080,583	1,060,231
Private Label [Member]
Investment securities available for sale:
Amortized Cost	1,535	1,722
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(23)	(14)
Fair Value	1,512	1,709
Investment securities held to maturity:
Amortized Cost	0
Fair Value	0
GNMA Commercial Mortgage-Related Securities [Member]
Investment securities available for sale:
Amortized Cost	2,053,540	1,982,477
Gross Unrealized Gains	5,855	1,334
Gross Unrealized Losses	(11,530)	(28,501)
Fair Value	2,047,865	1,955,310
Investment securities held to maturity:
Amortized Cost	0
Fair Value	0
Other Debt And Other Equity Securities [Member]
Investment securities available for sale:
Amortized Cost	4,718	4,718
Gross Unrealized Gains	87	51
Gross Unrealized Losses	0	0
Fair Value	4,805	4,769
FNMA and FHLMC [Member] | Residential Related Securities [Member]
Investment securities available for sale:
Amortized Cost	1,268,929	1,388,995
Gross Unrealized Gains	35,321	33,791
Gross Unrealized Losses	(846)	(8,160)
Fair Value	1,303,404	1,414,626
Investment securities held to maturity:
Amortized Cost	40,404	41,469
Gross Unrealized Gains	797	513
Gross Unrealized Losses	(180)	(645)
Fair Value	41,021	41,337
GNMA [Member] | Residential Related Securities [Member]
Investment securities available for sale:
Amortized Cost	1,536,248	1,605,956
Gross Unrealized Gains	11,086	507
Gross Unrealized Losses	(79)	(16,460)
Fair Value	1,547,255	1,590,003
Investment securities held to maturity:
Amortized Cost	81,660	82,994
Gross Unrealized Gains	1,086	189
Gross Unrealized Losses	(5)	(309)
Fair Value	$ 82,741	$ 82,874

Investment Securities, AFS an47

Investment Securities, AFS and HTM Contractual Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Amortized Cost
Available for Sale, Due in one year or less	$ 2,500
Available for Sale, Due after one year through five years	3,200
Available for Sale, Due after five years through ten years	0
Available for Sale, Due after ten years	0
Available for Sale, Total debt securities	5,700
Investment securities available for sale, amortized cost	4,865,970	$ 4,984,867
Fair Value
Available for Sale, Due in one year or less	2,530
Available for Sale, Due after one year through five years	3,200
Available for Sale, Due after five years through ten years	0
Available for Sale, Due after ten years	0
Available for Sale, Total debt securities	5,730
Investment securities available for sale, at fair value	$ 4,905,841	4,967,414
Ratio of Fair Value to Amortized Cost	100.80%
Amortized Cost
Held to Maturity, Due in one year or less	$ 46,749
Held to Maturity, Due after one year through five years	243,423
Held to Maturity, Due after five years through ten years	245,683
Held to Maturity, Due after ten years	518,902
Held to Maturity, Debt Securities, Amortized Cost Basis	1,054,757
Held to Maturity Amortized Cost	1,176,821	1,168,230
Fair Value
Held to Maturity, Due in one year or less	32,151
Held to Maturity, Due after one year through five years	255,338
Held to Maturity, Due after five years through ten years	255,755
Held to Maturity, Due after ten years	537,339
Held to Maturity, Securities, Debt Securities	1,080,583
Held to Maturity, Total debt securities	$ 1,204,345	1,184,442
Ratio of Fair Value to Amortized Cost	102.30%
Private Label [Member]
Amortized Cost
Investment securities available for sale, amortized cost	$ 1,535	1,722
Fair Value
Investment securities available for sale, at fair value	1,512	1,709
Amortized Cost
Held to Maturity Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities	0
GNMA Commercial Mortgage-Related Securities [Member]
Amortized Cost
Investment securities available for sale, amortized cost	2,053,540	1,982,477
Fair Value
Investment securities available for sale, at fair value	2,047,865	1,955,310
Amortized Cost
Held to Maturity Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities	0
Equity Securities [Member]
Amortized Cost
Investment securities available for sale, amortized cost	18
Fair Value
Investment securities available for sale, at fair value	75
Amortized Cost
Held to Maturity Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities	0
FNMA and FHLMC [Member] | Residential Related Securities [Member]
Amortized Cost
Investment securities available for sale, amortized cost	1,268,929	1,388,995
Fair Value
Investment securities available for sale, at fair value	1,303,404	1,414,626
Amortized Cost
Held to Maturity Amortized Cost	40,404	41,469
Fair Value
Held to Maturity, Total debt securities	41,021	41,337
GNMA [Member] | Residential Related Securities [Member]
Amortized Cost
Investment securities available for sale, amortized cost	1,536,248	1,605,956
Fair Value
Investment securities available for sale, at fair value	1,547,255	1,590,003
Amortized Cost
Held to Maturity Amortized Cost	81,660	82,994
Fair Value
Held to Maturity, Total debt securities	$ 82,741	$ 82,874

Investment Securities, Gains, L

Investment Securities, Gains, Losses, and Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	$ 3,287	$ 0
Gross losses	(189)	0
Total investment securities gains, net	3,098	0
Proceeds from sales of securities	$ 119,379	$ 289

Investment Securities, AFS an49

Investment Securities, AFS and HTM Securities Gross Unrealized Losses (Details) $ in Thousands	Mar. 31, 2016USD ($)security	Dec. 31, 2015USD ($)security
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	$ (1,470)	$ (27,621)
Unrealized losses on available for sale securities, 12 months or more	(11,008)	(25,516)
Total unrealized losses on available for sale securities	(12,478)	(53,137)
Fair value of unrealized losses on available for sale securities, less than 12 months	600,609	2,789,260
Fair value of unrealized losses on available for sale securities, 12 months or more	708,913	787,969
Total fair value of unrealized losses on available for sale securities	$ 1,309,522	$ 3,577,229
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	23	105
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	36	38
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (78)	$ (524)
Unrealized losses on held to maturity securities, 12 months or more	(253)	(769)
Total unrealized losses on held to maturity securities	(331)	(1,293)
Fair value of unrealized losses on held to maturity securities, less than 12 months	$ 11,209	$ 81,390
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer | security	23	30
Fair value of unrealized losses on held to maturity securities, 12 months or more	$ 20,734	$ 27,157
Total fair value of unrealized losses on held to maturity securities	$ 31,943	$ 108,547
Held-to-maturity, Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months | security	21	84
US Treasury Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months		$ (2)
Unrealized losses on available for sale securities, 12 months or more		0
Total unrealized losses on available for sale securities		(2)
Fair value of unrealized losses on available for sale securities, less than 12 months		997
Fair value of unrealized losses on available for sale securities, 12 months or more		0
Total fair value of unrealized losses on available for sale securities		$ 997
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security		1
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security		0
Obligations of state and political subdivisions (municipal securities) [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (75)	$ (146)
Unrealized losses on held to maturity securities, 12 months or more	(71)	(193)
Total unrealized losses on held to maturity securities	(146)	(339)
Fair value of unrealized losses on held to maturity securities, less than 12 months	10,029	23,137
Fair value of unrealized losses on held to maturity securities, 12 months or more	5,599	9,254
Total fair value of unrealized losses on held to maturity securities	$ 15,628	$ 32,391
Obligations of state and political subdivisions (municipal securities) [Member] | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	20	53
Obligations of state and political subdivisions (municipal securities) [Member] | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	17	24
Private Label [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	$ (1)	$ (1)
Unrealized losses on available for sale securities, 12 months or more	(22)	(13)
Total unrealized losses on available for sale securities	(23)	(14)
Fair value of unrealized losses on available for sale securities, less than 12 months	76	83
Fair value of unrealized losses on available for sale securities, 12 months or more	1,382	1,565
Total fair value of unrealized losses on available for sale securities	$ 1,458	$ 1,648
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	1	1
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	3	3
GNMA Commercial Mortgage-Related Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	$ (1,390)	$ (9,610)
Unrealized losses on available for sale securities, 12 months or more	(10,140)	(18,891)
Total unrealized losses on available for sale securities	(11,530)	(28,501)
Fair value of unrealized losses on available for sale securities, less than 12 months	558,620	1,132,844
Fair value of unrealized losses on available for sale securities, 12 months or more	448,861	448,218
Total fair value of unrealized losses on available for sale securities	$ 1,007,481	$ 1,581,062
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	20	40
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	21	21
FNMA and FHLMC [Member] | Residential Related Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	$ 0	$ (1,548)
Unrealized losses on available for sale securities, 12 months or more	(846)	(6,612)
Total unrealized losses on available for sale securities	(846)	(8,160)
Fair value of unrealized losses on available for sale securities, less than 12 months	0	220,852
Fair value of unrealized losses on available for sale securities, 12 months or more	258,670	338,186
Total fair value of unrealized losses on available for sale securities	$ 258,670	$ 559,038
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	0	17
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	12	14
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ (3)	$ (177)
Unrealized losses on held to maturity securities, 12 months or more	(177)	(468)
Total unrealized losses on held to maturity securities	(180)	(645)
Fair value of unrealized losses on held to maturity securities, less than 12 months	1,180	12,754
Fair value of unrealized losses on held to maturity securities, 12 months or more	13,587	11,106
Total fair value of unrealized losses on held to maturity securities	$ 14,767	$ 23,860
FNMA and FHLMC [Member] | Residential Related Securities [Member] | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	1	10
FNMA and FHLMC [Member] | Residential Related Securities [Member] | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	5	3
GNMA [Member] | Residential Related Securities [Member]
Unrealized losses and fair value of available for sale securities , by investment category and time length
Unrealized losses on available for sale securities, less than 12 months	$ (79)	$ (16,460)
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	(79)	(16,460)
Fair value of unrealized losses on available for sale securities, less than 12 months	41,913	1,434,484
Fair value of unrealized losses on available for sale securities, 12 months or more	0	0
Total fair value of unrealized losses on available for sale securities	$ 41,913	$ 1,434,484
Number of available for sale securities in a continuous unrealized loss position less than twelve months | security	2	46
Number of available for sale securities in a continuous unrealized loss position for twelve months or more | security	0	0
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Unrealized losses on held to maturity securities, less than 12 months	$ 0	$ (201)
Unrealized losses on held to maturity securities, 12 months or more	(5)	(108)
Total unrealized losses on held to maturity securities	(5)	(309)
Fair value of unrealized losses on held to maturity securities, less than 12 months	0	45,499
Fair value of unrealized losses on held to maturity securities, 12 months or more	1,548	6,797
Total fair value of unrealized losses on held to maturity securities	$ 1,548	$ 52,296
GNMA [Member] | Residential Related Securities [Member] | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Less Than One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	0	21
GNMA [Member] | Residential Related Securities [Member] | Held To Maturity Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions Greater Than Or Equal To One Year [Member]
Held-to-maturity Securities Continuous Unrealized Loss Position [Abstract]
Number of held to maturity securities in a continuous unrealized loss position | security	1	3

Investment Securities (Details

Investment Securities (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of securities	$ 119,379	$ 289
Marketable Securities, Gain (Loss)	3,098	$ 0
Investment Securities (Textuals) [Abstract]
Securities pledged as collateral	2,700,000		$ 3,200,000
Federal Home Loan Bank Stock	108,000		74,000
Federal Reserve Bank Stock	$ 73,000		$ 73,000

Loans, Loan Composition (Detail

Loans, Loan Composition (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 19,227,240	$ 18,714,343
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans	6,511,648	6,190,683
Commercial real estate — owner occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans	917,285	918,212
Commercial and business lending
Loans and Leases Receivable Disclosure [Line Items]
Total loans	7,428,933	7,108,895
Commercial real estate — investor
Loans and Leases Receivable Disclosure [Line Items]
Total loans	3,276,733	3,234,266
Real estate construction
Loans and Leases Receivable Disclosure [Line Items]
Total loans	1,184,398	1,162,145
Commercial real estate lending
Loans and Leases Receivable Disclosure [Line Items]
Total loans	4,461,131	4,396,411
Total commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans	11,890,064	11,505,306
Residential mortgage
Loans and Leases Receivable Disclosure [Line Items]
Total loans	5,944,457	5,783,267
Home equity
Loans and Leases Receivable Disclosure [Line Items]
Total loans	982,994	1,005,802
Other consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans	409,725	419,968
Total consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 7,337,176	$ 7,209,037

Loans Loans, Loans by Credit Qu

Loans Loans, Loans by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 19,227,240	$ 18,714,343
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	18,197,939	17,804,216
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	341,831	430,152
Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	401,075	301,717
Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	286,395	178,258
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,511,648	6,190,683
Commercial and industrial | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,713,979	5,522,809
Commercial and industrial | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	272,090	341,169
Commercial and industrial | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	328,464	233,130
Commercial and industrial | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	197,115	93,575
Commercial real estate — owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	917,285	918,212
Commercial real estate — owner occupied | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	834,879	835,572
Commercial real estate — owner occupied | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	31,856	38,885
Commercial real estate — owner occupied | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	41,107	35,706
Commercial real estate — owner occupied | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	9,443	8,049
Commercial and business lending
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	7,428,933	7,108,895
Commercial and business lending | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,548,858	6,358,381
Commercial and business lending | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	303,946	380,054
Commercial and business lending | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	369,571	268,836
Commercial and business lending | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	206,558	101,624
Commercial real estate — investor
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,276,733	3,234,266
Commercial real estate — investor | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,208,338	3,153,703
Commercial real estate — investor | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	30,680	45,976
Commercial real estate — investor | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	25,385	25,944
Commercial real estate — investor | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	12,330	8,643
Real estate construction
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,184,398	1,162,145
Real estate construction | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,180,914	1,157,034
Real estate construction | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	222	252
Real estate construction | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,422	3,919
Real estate construction | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	840	940
Commercial real estate lending
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	4,461,131	4,396,411
Commercial real estate lending | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	4,389,252	4,310,737
Commercial real estate lending | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	30,902	46,228
Commercial real estate lending | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	27,807	29,863
Commercial real estate lending | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	13,170	9,583
Total commercial
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	11,890,064	11,505,306
Total commercial | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	10,938,110	10,669,118
Total commercial | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	334,848	426,282
Total commercial | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	397,378	298,699
Total commercial | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	219,728	111,207
Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,944,457	5,783,267
Residential mortgage | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,883,743	5,727,437
Residential mortgage | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,014	1,552
Residential mortgage | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,488	2,796
Residential mortgage | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	52,212	51,482
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	982,994	1,005,802
Home equity | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	967,267	988,574
Home equity | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,446	1,762
Home equity | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	209	222
Home equity | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	14,072	15,244
Other consumer
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	409,725	419,968
Other consumer | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	408,819	419,087
Other consumer | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	523	556
Other consumer | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Other consumer | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	383	325
Total consumer
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	7,337,176	7,209,037
Total consumer | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	7,259,829	7,135,098
Total consumer | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,983	3,870
Total consumer | Potential Problem [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,697	3,018
Total consumer | Nonaccrual Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 66,667	$ 67,051

Loans, Loans by Past Due Status

Loans, Loans by Past Due Status (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Summarized details of Loans
Current	$ 18,923,228	$ 18,510,978
Financing Receivable, Recorded Investment, Nonaccrual Status	286,395	178,258
Total loans	19,227,240	18,714,343
Accruing loans past due 90 days or more	2,000	2,000
Nonaccrual Loans, Current Portion	$ 230,000	$ 124,000
Percent of current nonaccrual loans	80.00%	69.00%
Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	$ 12,977	$ 20,181
Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	3,011	3,278
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	1,629	1,648
Commercial and industrial
Summarized details of Loans
Current	6,311,415	6,095,848
Financing Receivable, Recorded Investment, Nonaccrual Status	197,115	93,575
Total loans	6,511,648	6,190,683
Commercial and industrial | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	2,665	602
Commercial and industrial | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	236	409
Commercial and industrial | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	217	249
Commercial real estate — owner occupied
Summarized details of Loans
Current	907,322	903,021
Financing Receivable, Recorded Investment, Nonaccrual Status	9,443	8,049
Total loans	917,285	918,212
Commercial real estate — owner occupied | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	520	7,142
Commercial real estate — owner occupied | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Commercial real estate — owner occupied | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Commercial and business lending
Summarized details of Loans
Current	7,218,737	6,998,869
Financing Receivable, Recorded Investment, Nonaccrual Status	206,558	101,624
Total loans	7,428,933	7,108,895
Commercial and business lending | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	3,185	7,744
Commercial and business lending | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	236	409
Commercial and business lending | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	217	249
Commercial real estate — investor
Summarized details of Loans
Current	3,263,331	3,225,332
Financing Receivable, Recorded Investment, Nonaccrual Status	12,330	8,643
Total loans	3,276,733	3,234,266
Commercial real estate — investor | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	748	291
Commercial real estate — investor | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	324	0
Commercial real estate — investor | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Real estate construction
Summarized details of Loans
Current	1,183,143	1,160,909
Financing Receivable, Recorded Investment, Nonaccrual Status	840	940
Total loans	1,184,398	1,162,145
Real estate construction | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	415	270
Real estate construction | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	26
Real estate construction | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Commercial Real Estate Lending [Member]
Summarized details of Loans
Current	4,446,474	4,386,241
Financing Receivable, Recorded Investment, Nonaccrual Status	13,170	9,583
Total loans	4,461,131	4,396,411
Commercial Real Estate Lending [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	1,163	561
Commercial Real Estate Lending [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	324	26
Commercial Real Estate Lending [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Commercial Financing Receivable [Member]
Summarized details of Loans
Current	11,665,211	11,385,110
Financing Receivable, Recorded Investment, Nonaccrual Status	219,728	111,207
Total loans	11,890,064	11,505,306
Commercial Financing Receivable [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	4,348	8,305
Commercial Financing Receivable [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	560	435
Commercial Financing Receivable [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	217	249
Residential mortgage
Summarized details of Loans
Current	5,888,651	5,726,855
Financing Receivable, Recorded Investment, Nonaccrual Status	52,212	51,482
Total loans	5,944,457	5,783,267
Residential mortgage | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	3,199	4,491
Residential mortgage | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	395	439
Residential mortgage | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Home equity
Summarized details of Loans
Current	963,118	982,639
Financing Receivable, Recorded Investment, Nonaccrual Status	14,072	15,244
Total loans	982,994	1,005,802
Home equity | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	4,410	6,190
Home equity | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	1,394	1,729
Home equity | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Other consumer
Summarized details of Loans
Current	406,248	416,374
Financing Receivable, Recorded Investment, Nonaccrual Status	383	325
Total loans	409,725	419,968
Other consumer | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	1,020	1,195
Other consumer | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	662	675
Other consumer | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	1,412	1,399
Consumer Loan [Member]
Summarized details of Loans
Current	7,258,017	7,125,868
Financing Receivable, Recorded Investment, Nonaccrual Status	66,667	67,051
Total loans	7,337,176	7,209,037
Consumer Loan [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Summarized details of Loans
Total Past Due	8,629	11,876
Consumer Loan [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Summarized details of Loans
Total Past Due	2,451	2,843
Consumer Loan [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	$ 1,412	$ 1,399

Loans, Impaired Loans Recorded

Loans, Impaired Loans Recorded Investment, Unpaid Principal Balance, Related Allowance, Average Recorded Investment, and Interest Income Recognized (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	$ 371,992	$ 265,621
Unpaid Principal Balance	395,678	284,433
Related Allowance	39,109	33,669
Average Recorded Investment	373,687	273,011
Interest Income Recognized	$ 2,117	$ 8,716
Net Recorded Investment of the Impaired Loans	84.00%	82.00%
Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	$ 227,871	$ 186,275
Unpaid Principal Balance	238,082	197,109
Related Allowance	39,109	33,669
Average Recorded Investment	229,224	178,871
Interest Income Recognized	1,981	6,798
Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	144,121	79,346
Unpaid Principal Balance	157,596	87,324
Related Allowance	0	0
Average Recorded Investment	144,463	94,140
Interest Income Recognized	136	1,918
Commercial and industrial
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	226,023	122,868
Unpaid Principal Balance	237,772	131,668
Related Allowance	14,595	8,162
Average Recorded Investment	226,679	126,406
Interest Income Recognized	704	2,512
Commercial and industrial | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	105,780	57,785
Unpaid Principal Balance	106,837	59,409
Related Allowance	14,595	8,162
Average Recorded Investment	106,280	46,833
Interest Income Recognized	613	855
Commercial and industrial | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	120,243	65,083
Unpaid Principal Balance	130,935	72,259
Related Allowance	0	0
Average Recorded Investment	120,399	79,573
Interest Income Recognized	91	1,657
Commercial real estate — owner occupied
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	17,136	15,926
Unpaid Principal Balance	19,601	16,452
Related Allowance	554	448
Average Recorded Investment	17,267	16,621
Interest Income Recognized	89	427
Commercial real estate — owner occupied | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	10,477	9,705
Unpaid Principal Balance	10,596	9,804
Related Allowance	554	448
Average Recorded Investment	10,552	10,087
Interest Income Recognized	89	412
Commercial real estate — owner occupied | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	6,659	6,221
Unpaid Principal Balance	9,005	6,648
Related Allowance	0	0
Average Recorded Investment	6,715	6,534
Interest Income Recognized	0	15
Commercial and business lending
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	243,159	138,794
Unpaid Principal Balance	257,373	148,120
Related Allowance	15,149	8,610
Average Recorded Investment	243,946	143,027
Interest Income Recognized	793	2,939
Commercial and business lending | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	116,257	67,490
Unpaid Principal Balance	117,433	69,213
Related Allowance	15,149	8,610
Average Recorded Investment	116,832	56,920
Interest Income Recognized	702	1,267
Commercial and business lending | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	126,902	71,304
Unpaid Principal Balance	139,940	78,907
Related Allowance	0	0
Average Recorded Investment	127,114	86,107
Interest Income Recognized	91	1,672
Commercial real estate — investor
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	33,323	30,558
Unpaid Principal Balance	34,414	32,284
Related Allowance	1,244	1,831
Average Recorded Investment	33,396	31,041
Interest Income Recognized	461	2,004
Commercial real estate — investor | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	23,494	27,822
Unpaid Principal Balance	24,430	29,444
Related Allowance	1,244	1,831
Average Recorded Investment	23,541	28,278
Interest Income Recognized	461	1,914
Commercial real estate — investor | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	9,829	2,736
Unpaid Principal Balance	9,984	2,840
Related Allowance	0	0
Average Recorded Investment	9,855	2,763
Interest Income Recognized	0	90
Real estate construction
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,226	1,450
Unpaid Principal Balance	1,812	2,154
Related Allowance	412	453
Average Recorded Investment	1,237	1,667
Interest Income Recognized	14	66
Real estate construction | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,226	1,450
Unpaid Principal Balance	1,812	2,154
Related Allowance	412	453
Average Recorded Investment	1,237	1,667
Interest Income Recognized	14	66
Real estate construction | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Commercial Real Estate Lending [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	34,549	32,008
Unpaid Principal Balance	36,226	34,438
Related Allowance	1,656	2,284
Average Recorded Investment	34,633	32,708
Interest Income Recognized	475	2,070
Commercial Real Estate Lending [Member] | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	24,720	29,272
Unpaid Principal Balance	26,242	31,598
Related Allowance	1,656	2,284
Average Recorded Investment	24,778	29,945
Interest Income Recognized	475	1,980
Commercial Real Estate Lending [Member] | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	9,829	2,736
Unpaid Principal Balance	9,984	2,840
Related Allowance	0	0
Average Recorded Investment	9,855	2,763
Interest Income Recognized	0	90
Commercial Financing Receivable [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	277,708	170,802
Unpaid Principal Balance	293,599	182,558
Related Allowance	16,805	10,894
Average Recorded Investment	278,579	175,735
Interest Income Recognized	1,268	5,009
Commercial Financing Receivable [Member] | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	140,977	96,762
Unpaid Principal Balance	143,675	100,811
Related Allowance	16,805	10,894
Average Recorded Investment	141,610	86,865
Interest Income Recognized	1,177	3,247
Commercial Financing Receivable [Member] | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	136,731	74,040
Unpaid Principal Balance	149,924	81,747
Related Allowance	0	0
Average Recorded Investment	136,969	88,870
Interest Income Recognized	91	1,762
Residential mortgage
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	72,019	71,352
Unpaid Principal Balance	77,644	76,117
Related Allowance	12,351	12,462
Average Recorded Investment	72,660	72,909
Interest Income Recognized	583	2,500
Residential mortgage | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	65,281	66,590
Unpaid Principal Balance	70,624	71,084
Related Allowance	12,351	12,462
Average Recorded Investment	65,819	68,183
Interest Income Recognized	548	2,374
Residential mortgage | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	6,738	4,762
Unpaid Principal Balance	7,020	5,033
Related Allowance	0	0
Average Recorded Investment	6,841	4,726
Interest Income Recognized	35	126
Home equity
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	20,989	22,313
Unpaid Principal Balance	23,103	24,533
Related Allowance	9,732	10,118
Average Recorded Investment	21,157	23,168
Interest Income Recognized	258	1,177
Home equity | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	20,337	21,769
Unpaid Principal Balance	22,451	23,989
Related Allowance	9,732	10,118
Average Recorded Investment	20,504	22,624
Interest Income Recognized	248	1,147
Home equity | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	652	544
Unpaid Principal Balance	652	544
Related Allowance	0	0
Average Recorded Investment	653	544
Interest Income Recognized	10	30
Other consumer
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,276	1,154
Unpaid Principal Balance	1,332	1,225
Related Allowance	221	195
Average Recorded Investment	1,291	1,199
Interest Income Recognized	8	30
Other consumer | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,276	1,154
Unpaid Principal Balance	1,332	1,225
Related Allowance	221	195
Average Recorded Investment	1,291	1,199
Interest Income Recognized	8	30
Other consumer | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Consumer Loan [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	94,284	94,819
Unpaid Principal Balance	102,079	101,875
Related Allowance	22,304	22,775
Average Recorded Investment	95,108	97,276
Interest Income Recognized	849	3,707
Consumer Loan [Member] | Loans With Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	86,894	89,513
Unpaid Principal Balance	94,407	96,298
Related Allowance	22,304	22,775
Average Recorded Investment	87,614	92,006
Interest Income Recognized	804	3,551
Consumer Loan [Member] | Loans With No Related Allowance [Member]
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	7,390	5,306
Unpaid Principal Balance	7,672	5,577
Related Allowance	0	0
Average Recorded Investment	7,494	5,270
Interest Income Recognized	$ 45	$ 156

Loans, Troubled Debt Restructur

Loans, Troubled Debt Restructurings Performing and Nonaccrual (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	$ 85,597	$ 87,363
Nonaccrual Restructured Loans	35,232	37,684
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	28,908	29,293
Nonaccrual Restructured Loans	2,711	1,714
Commercial real estate — owner occupied
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	7,693	7,877
Nonaccrual Restructured Loans	2,689	2,703
Commercial real estate — investor
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	20,993	21,915
Nonaccrual Restructured Loans	1,356	3,936
Real estate construction
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	386	510
Nonaccrual Restructured Loans	182	177
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	19,807	19,870
Nonaccrual Restructured Loans	23,845	24,592
Home Equity Portfolio Segments [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	6,917	7,069
Nonaccrual Restructured Loans	4,416	4,522
Other consumer
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	893	829
Nonaccrual Restructured Loans	$ 33	$ 40

Loans, Loans Modified in a Trou

Loans, Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)loan	Mar. 31, 2015USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	59	77
Recorded Investment	$ 4,498	$ 11,409
Unpaid Principal Balance	$ 4,710	$ 11,598
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	7	2
Recorded Investment	$ 1,483	$ 196
Unpaid Principal Balance	$ 1,522	$ 208
Commercial real estate — owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	5
Recorded Investment	$ 125	$ 3,585
Unpaid Principal Balance	$ 130	$ 3,641
Commercial real estate — investor
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	4
Recorded Investment	$ 0	$ 3,030
Unpaid Principal Balance	$ 0	$ 3,042
Real estate construction
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	0
Recorded Investment	$ 10	$ 0
Unpaid Principal Balance	$ 55	$ 0
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	30	30
Recorded Investment	$ 2,062	$ 2,816
Unpaid Principal Balance	$ 2,124	$ 2,864
Home Equity Portfolio Segments [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	20	36
Recorded Investment	$ 818	$ 1,782
Unpaid Principal Balance	$ 879	$ 1,843

Loans, Troubled Debt Restruct57

Loans, Troubled Debt Restructurings Subsequent Default (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)loan	Mar. 31, 2015USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	16	41
Recorded Investment | $	$ 1,314	$ 2,391
Commercial real estate — owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	1
Recorded Investment | $	$ 0	$ 297
Real estate construction
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	0
Recorded Investment | $	$ 10	$ 0
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	7	16
Recorded Investment | $	$ 1,151	$ 1,239
Home Equity Portfolio Segments [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	8	24
Recorded Investment | $	$ 153	$ 855

Loans, Changes in the Allowance

Loans, Changes in the Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2016	Dec. 31, 2015
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	$ 274,264	$ 266,302
Charge offs	(21,245)	(52,280)
Recoveries	4,351	22,242
Net charge offs	(16,894)	(30,038)
Provision for loan losses	20,000	38,000
Balance at end of year	277,370	274,264
Allowance for loan losses:
Individually evaluated for impairment			$ 14,093	$ 7,963
Collectively evaluated for impairment			263,277	266,301
Total allowance for loan losses	274,264	266,302	277,370	274,264
Loans [Abstract]
Individually evaluated for impairment			220,794	111,487
Collectively evaluated for impairment			19,006,446	18,602,856
Total loans			19,227,240	18,714,343
Commercial and industrial
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	129,959	117,635
Charge offs	(16,894)	(27,687)
Recoveries	1,958	9,821
Net charge offs	(14,936)	(17,866)
Provision for loan losses	24,470	30,190
Balance at end of year	139,493	129,959
Allowance for loan losses:
Individually evaluated for impairment			14,005	7,522
Collectively evaluated for impairment			125,488	122,437
Total allowance for loan losses	129,959	117,635	139,493	129,959
Loans [Abstract]
Individually evaluated for impairment			195,341	91,569
Collectively evaluated for impairment			6,316,307	6,099,114
Total loans			6,511,648	6,190,683
Commercial real estate — owner occupied
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	18,680	16,510
Charge offs	(76)	(2,645)
Recoveries	33	921
Net charge offs	(43)	(1,724)
Provision for loan losses	(2,059)	3,894
Balance at end of year	16,578	18,680
Allowance for loan losses:
Individually evaluated for impairment			74	0
Collectively evaluated for impairment			16,504	18,680
Total allowance for loan losses	18,680	16,510	16,578	18,680
Loans [Abstract]
Individually evaluated for impairment			7,500	6,221
Collectively evaluated for impairment			909,785	911,991
Total loans			917,285	918,212
Commercial real estate — investor
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	43,018	46,333
Charge offs	(176)	(4,645)
Recoveries	1,415	4,157
Net charge offs	1,239	(488)
Provision for loan losses	(2,233)	(2,827)
Balance at end of year	42,024	43,018
Allowance for loan losses:
Individually evaluated for impairment			0	229
Collectively evaluated for impairment			42,024	42,789
Total allowance for loan losses	43,018	46,333	42,024	43,018
Loans [Abstract]
Individually evaluated for impairment			9,829	5,460
Collectively evaluated for impairment			3,266,904	3,228,806
Total loans			3,276,733	3,234,266
Real Estate Construction Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	25,266	20,999
Charge offs	(54)	(750)
Recoveries	26	2,268
Net charge offs	(28)	1,518
Provision for loan losses	(3,498)	2,749
Balance at end of year	21,740	25,266
Allowance for loan losses:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			21,740	25,266
Total allowance for loan losses	25,266	20,999	21,740	25,266
Loans [Abstract]
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			1,184,398	1,162,145
Total loans			1,184,398	1,162,145
Residential Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	28,261	31,926
Charge offs	(1,390)	(5,636)
Recoveries	158	1,077
Net charge offs	(1,232)	(4,559)
Provision for loan losses	2,030	894
Balance at end of year	29,059	28,261
Allowance for loan losses:
Individually evaluated for impairment			14	166
Collectively evaluated for impairment			29,045	28,095
Total allowance for loan losses	28,261	31,926	29,059	28,261
Loans [Abstract]
Individually evaluated for impairment			7,472	6,956
Collectively evaluated for impairment			5,936,985	5,776,311
Total loans			5,944,457	5,783,267
Home Equity Portfolio Segments [Member]
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	23,555	26,464
Charge offs	(1,746)	(7,048)
Recoveries	600	3,233
Net charge offs	(1,146)	(3,815)
Provision for loan losses	721	906
Balance at end of year	23,130	23,555
Allowance for loan losses:
Individually evaluated for impairment			0	46
Collectively evaluated for impairment			23,130	23,509
Total allowance for loan losses	23,555	26,464	23,130	23,555
Loans [Abstract]
Individually evaluated for impairment			652	1,281
Collectively evaluated for impairment			982,342	1,004,521
Total loans			982,994	1,005,802
Other consumer [Member]
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of year	5,525	6,435
Charge offs	(909)	(3,869)
Recoveries	161	765
Net charge offs	(748)	(3,104)
Provision for loan losses	569	2,194
Balance at end of year	5,346	5,525
Allowance for loan losses:
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			5,346	5,525
Total allowance for loan losses	$ 5,525	$ 6,435	5,346	5,525
Loans [Abstract]
Individually evaluated for impairment			0	0
Collectively evaluated for impairment			409,725	419,968
Total loans			$ 409,725	$ 419,968

Loans, Changes in the Allowan59

Loans, Changes in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Change in the allowance for unfunded commitments
Balance at beginning of year	$ 24,000
Balance at end of year	24,000	$ 24,000
Reserve for Off-balance Sheet Activities [Member]
Change in the allowance for unfunded commitments
Balance at beginning of year	24,400	24,900
Provision for unfunded commitments	0	(500)
Balance at end of year	$ 24,400	$ 24,400

Loans (Details Textuals)

Loans (Details Textuals) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Receivables [Abstract]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 4,498	$ 11,409
Restructured Loans Subsequently Accruing	470
Ytd Restructured Loans Still On Nonaccrual	$ 4,000

Goodwill and Intangible Asset61

Goodwill and Intangible Assets (Details Textuals) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill acquired during period	$ 3,000
Additions to finite-lived intangible assets	1,000	$ 12,000
Goodwill	971,951	968,844
Fully amortized core deposits intangibles	$ 15,000
Ahmann and Martin Company [Member]
Business Acquisition [Line Items]
Goodwill acquired during period		$ 40,000

Goodwill and Intangible Assets,

Goodwill and Intangible Assets, Summary of Core Deposit and Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Summary of core deposit intangibles and other intangibles
Additions during the period	$ 1,000		$ 12,000
Amortization of other intangible assets	504	$ 801
Core Deposit Intangibles [Member]
Summary of core deposit intangibles and other intangibles
Gross carrying amount	4,385		19,545
Accumulated amortization	(4,062)		(19,152)
Total Estimated Amortization Expense	323		393
Amortization of other intangible assets	70		1,404
Other Intangible Assets [Member]
Summary of core deposit intangibles and other intangibles
Gross carrying amount	32,410		31,398
Accumulated amortization	(15,767)		(15,333)
Total Estimated Amortization Expense	16,643		16,065
Additions during the period	1,012		12,115
Amortization of other intangible assets	$ 434		$ 1,690

Goodwill and Intangible Asset63

Goodwill and Intangible Assets, Mortgage Servicing Rights Roll-Forward (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Mortgage servicing rights:
Mortgage servicing rights at beginning of year	$ 62,150	$ 61,379
Additions	1,856	12,372
Amortization	(2,874)	(11,601)
Mortgage servicing rights at end of year	61,132	62,150
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Valuation allowance at beginning of year	(809)	(1,234)
(Additions) recoveries, net	(909)	425
Valuation allowance at end of year	(1,718)	(809)
Mortgage servicing rights, net	59,414	61,341
Fair value of mortgage servicing rights	61,410	70,686
Portfolio of residential mortgage loans serviced for others (“servicing portfolio”)	$ 7,876,888	$ 7,915,224
Mortgage servicing rights, net to servicing portfolio	0.75%	0.77%
Mortgage servicing rights expense	$ 3,783	$ 11,176

Goodwill and Intangible Asset64

Goodwill and Intangible Assets, Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Core Deposit Intangibles [Member]
Estimated future amortization expense
Nine months ending December 31, 2016	$ 211
Year ending December 31, 2017	112
Year ending December 31, 2018	0
Year ending December 31, 2019	0
Year ending December 31, 2020	0
Year ending December 31, 2021	0
Beyond 2,021	0
Total Estimated Amortization Expense	323	$ 393
Other Intangible Assets [Member]
Estimated future amortization expense
Nine months ending December 31, 2016	1,378
Year ending December 31, 2017	1,786
Year ending December 31, 2018	1,756
Year ending December 31, 2019	1,457
Year ending December 31, 2020	1,340
Year ending December 31, 2021	1,316
Beyond 2,021	7,610
Total Estimated Amortization Expense	16,643	$ 16,065
Mortgage Service Rights [Member]
Estimated future amortization expense
Nine months ending December 31, 2016	8,850
Year ending December 31, 2017	9,674
Year ending December 31, 2018	7,761
Year ending December 31, 2019	6,313
Year ending December 31, 2020	5,169
Year ending December 31, 2021	4,265
Beyond 2,021	19,100
Total Estimated Amortization Expense	$ 61,132

Short and Long-Term Funding (Co

Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Short-term Funding [Abstract]
Federal funds purchased		$ 74,985	$ 47,870
Securities sold under agreements to repurchase		508,262	383,568
Federal funds purchased and securities sold under agreements to repurchase		583,247	431,438
FHLB advances		770,000	335,000
Commercial paper		64,161	67,978
Other short-term funding		834,161	402,978
Total short-term funding		1,417,408	834,416
Long-term Funding
FHLB advances		2,365,216	1,750,225
Senior notes, at par		250,000	680,000
Subordinated notes, at par		250,000	250,000
Other long-term funding and capitalized costs (1)		(3,900)	(4,061)
Total long-term funding	[1]	2,861,316	2,676,164
Total short and long-term funding		$ 4,278,724	$ 3,510,580
[1]	During the first quarter of 2016, the Corporation adopted a new accounting standard related to simplifying the presentation of debt issuance costs. Under this new accounting standard, debt issuance costs are still capitalized; however, they are reflected on the balance sheet with the related debt issued rather than within other assets. All prior periods have been restated to reflect this change in presentation. See Note 3 for additional information on this new accounting standard.

Short and Long-Term Funding (Lo

Short and Long-Term Funding (Long-term Funding Narrative) (Details) - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2014	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2011	Mar. 31, 2011
Subordinated Borrowing [Line Items]
Carrying Value of Federal Funds Purchased, Securities Sold under Agreements to Repurchase, and Deposits Received for Securities Loaned		$ 643
Federal Home Loan Bank, Advances, Weighted Average Interest Rate		0.29%	0.24%
Two Thousand Eleven Senior Notes [Member]
Subordinated Borrowing [Line Items]
New Senior Debt Issued				$ 130	$ 300
Debt Instrument, Interest Rate, Stated Percentage					5.125%
Two Thousand Fourteen Senior Notes [Member]
Subordinated Borrowing [Line Items]
New Senior Debt Issued	$ 250
Debt Instrument, Interest Rate, Stated Percentage	2.75%
Two Thousand Fourteen Subordinated Notes [Member]
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures Issued	$ 250
Debt Instrument, Term	10 years
Subordinated Borrowing, Interest Rate	4.25%

Short and Long-Term Funding (Re

Short and Long-Term Funding (Remaining Contractual Maturity of the Securities Sold Under Agreements to Repurchase) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	$ 508,262	$ 383,568
Securities sold under agreements to repurchase	508,262	383,568
Overnight and Continuous
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	508,262	383,568
Up to 30 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
30-90 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
Greater than 90 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
Government-Sponsored Enterprise (GSE) [Member]
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	508,262	383,568
Government-Sponsored Enterprise (GSE) [Member] | Overnight and Continuous
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	508,262	383,568
Government-Sponsored Enterprise (GSE) [Member] | Up to 30 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
Government-Sponsored Enterprise (GSE) [Member] | 30-90 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
Government-Sponsored Enterprise (GSE) [Member] | Greater than 90 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	$ 0	$ 0

Derivative and Hedging Activi68

Derivative and Hedging Activities, Derivative Instruments Not Designated as Hedging Instruments (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Trading Assets [Member] | Interest Rate-related instruments - customer and mirror [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	$ 1,806,688	$ 1,665,965
Fair Value	47,780	29,391
Trading Assets [Member] | Foreign currency exchange forwards [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	124,617	72,976
Fair Value	4,203	1,532
Trading Assets [Member] | Commodity contract [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	43,646	44,380
Fair Value	1,104	1,269
Trading Liabilities [Member] | Interest Rate-related instruments - customer and mirror [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	1,806,688	1,665,965
Fair Value	(50,145)	(30,886)
Trading Liabilities [Member] | Foreign currency exchange forwards [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	116,751	65,649
Fair Value	(4,097)	(1,398)
Trading Liabilities [Member] | Commodity contract [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	43,770	44,256
Fair Value	(981)	(1,146)
Other Assets [Member] | Interest rate lock commitments (mortgage) [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	418,136	271,530
Fair Value	2,689	958
Other Assets [Member] | Forward commitments (mortgage) [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount		231,798
Fair Value		403
Other Assets [Member] | Purchased options (time deposit) [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	103,475	104,582
Fair Value	2,228	2,715
Other Liabilities [Member] | Forward commitments (mortgage) [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	249,866
Fair Value	(1,732)
Other Liabilities [Member] | Written options (time deposit) [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	103,475	104,582
Fair Value	$ (2,228)	$ (2,715)

Derivative and Hedging Activi69

Derivative and Hedging Activities, Income Statement Category of the Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Capital market fees, net [Member] | Interest Rate-related instruments - customer and mirror [Member]
Gain (loss) on derivative instruments not designated as hedging instruments
Gain / (Loss) Recognized in Income	$ (870)	$ (294)
Capital market fees, net [Member] | Foreign currency exchange forwards [Member]
Gain (loss) on derivative instruments not designated as hedging instruments
Gain / (Loss) Recognized in Income	(28)	66
Capital market fees, net [Member] | Commodity contract [Member]
Gain (loss) on derivative instruments not designated as hedging instruments
Gain / (Loss) Recognized in Income	0	0
Mortgage banking, net [Member] | Interest rate lock commitments (mortgage) [Member]
Gain (loss) on derivative instruments not designated as hedging instruments
Gain / (Loss) Recognized in Income	1,731	1,738
Mortgage banking, net [Member] | Forward commitments (mortgage) [Member]
Gain (loss) on derivative instruments not designated as hedging instruments
Gain / (Loss) Recognized in Income	$ (2,135)	$ 640

Derivative and Hedging Activi70

Derivative and Hedging Activities (Details Textuals) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Investment securities and cash equivalents pledged as collateral	$ 28	$ 9
Derivative collateral right to reclaim cash	$ 31	$ 22

Balance Sheet Offsetting (Detai

Balance Sheet Offsetting (Details) - Interest Rate Contract [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 823	$ 1,466
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	823	1,466
Financial instruments	(823)	(1,466)
Collateral	0	0
Net amount	0	0
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	48,700	30,200
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	48,700	30,200
Financial instruments	(823)	(1,466)
Collateral	(47,877)	(28,734)
Net amount	$ 0	$ 0

Commitments, Off-Balance Shee72

Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings (Summary of Lending Related and Other Commitments) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale [Member]
Summary of lending-related and other commitments
Lending related commitments	$ 7,315,642	$ 7,402,518
Commercial Letters Of Credit [Member]
Summary of lending-related and other commitments
Lending related commitments	7,782	9,945
Standby Letters of Credit [Member]
Summary of lending-related and other commitments
Lending related commitments	278,740	296,508
Standby letters of credit, fair value	$ 3,000	$ 3,000

Commitments, Off-Balance Shee73

Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings (Details Textuals)	Jan. 11, 2016USD ($)loan_production_officebranch	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Unfunded commitments		$ 24,000,000	$ 24,000,000
Carrying value of investments		53,000,000	52,000,000
Commitments under unconsolidated projects		62,000,000	61,000,000
Commitment term	3 years
Mortgage loan commitment	$ 196,000,000
Number of branch opening commitments | branch	1
Number of loan production offices | loan_production_office	4
Conciliation agreement cost, commitment term	4 years
Loans repurchased under make whole requests		126,000	3,000,000
Loans sold to outside investors original amount		7,900,000,000
Loans sold to outside investors remaining outstanding amount		5,700,000,000
Residential mortgage loans sold with recourse risk		60,000,000	68,000,000
Residential mortgage loans sold with credit recourse risk		122,000,000	132,000,000
The Official Committee of Unsecured Creditors of World Marketing Chicago LLC v Associated Bank [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Damages sought	$ 6,000,000
Damages sought, cash	4,000,000
Damages sought, indebtedness	1,000,000
American Funds Service Company v Associated Bank [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Damages sought	$ 600,000
Reserve for Off-balance Sheet Activities [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Unfunded commitments		24,400,000	24,400,000	$ 24,900,000
Mortgage Repurchase Reserve [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Unfunded commitments		1,264,000	1,197,000	$ 3,258,000
Standby Letters of Credit [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Lines of Credit, Fair Value Disclosure		$ 3,000,000	$ 3,000,000

Commitments, Off-Balance Shee74

Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings (Residential Mortgage Repurchase Reserve) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Summary of changes in the residential mortgage repurchase reserve [Line Items]
Loans Repurchased Under Make Whole Requests	$ 126,000	$ 3,000,000
Residential mortgage repurchase reserve
Balance at beginning of year	24,000,000
Balance at end of year	24,000,000	24,000,000
Loss Reimbursement Claims Under Make Whole Requests	3,000	133,000
Loans Sold To Outside Investors Original Amount	7,900,000,000
Loans Sold To Outside Investors Remaining Outstanding Amount	5,700,000,000
Mortgage Repurchase Reserve [Member]
Residential mortgage repurchase reserve
Balance at beginning of year	1,197,000	3,258,000
Repurchase provision expense	70,000	428,000
Adjustments to provision expense	0	(2,450,000)
Charge offs, net	(3,000)	(39,000)
Balance at end of year	$ 1,264,000	$ 1,197,000

Fair Value Measurements, Assets

Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investment securities available for sale:
Investment securities available for sale	$ 4,905,841	$ 4,967,414
Trading assets	53,087	32,192
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	55,223	33,430
Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale:
Investment securities available for sale	2,605	2,566
Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale:
Investment securities available for sale	4,903,036	4,964,648
Trading assets	55,315	34,907
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	57,451	36,145
Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale:
Investment securities available for sale	200	200
Trading assets	2,689	1,361
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	1,732	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Investment securities available for sale:
Investment securities available for sale	1,000	997
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Debt And Other Equity Securities [Member]
Investment securities available for sale:
Investment securities available for sale	1,605	1,569
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Available-for-sale Securities [Member]
Investment securities available for sale:
Investment securities available for sale	2,605	2,566
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Government-Sponsored Enterprise (GSE) [Member]
Investment securities available for sale:
Investment securities available for sale	1,303,404	1,414,626
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | GNMA [Member]
Investment securities available for sale:
Investment securities available for sale	1,547,255	1,590,003
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Private Label [Member]
Investment securities available for sale:
Investment securities available for sale	1,512	1,709
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | GNMA Commercial Mortgage-Related Securities [Member]
Investment securities available for sale:
Investment securities available for sale	2,047,865	1,955,310
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Debt And Other Equity Securities [Member]
Investment securities available for sale:
Investment securities available for sale	3,000	3,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member]
Investment securities available for sale:
Investment securities available for sale	4,903,036	4,964,648
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate-related instruments - customer and mirror [Member]
Investment securities available for sale:
Trading assets	47,780	29,391
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	50,145	30,886
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign currency exchange forwards [Member]
Investment securities available for sale:
Trading assets	4,203	1,532
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	4,097	1,398
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commodity contract [Member]
Investment securities available for sale:
Trading assets	1,104	1,269
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	981	1,146
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Written options (time deposit) [Member]
Investment securities available for sale:
Trading assets	2,228	2,715
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	2,228	2,715
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Debt And Other Equity Securities [Member]
Investment securities available for sale:
Trading assets	200	200
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member]
Investment securities available for sale:
Investment securities available for sale	200	200
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate lock commitments (mortgage) [Member]
Investment securities available for sale:
Trading assets	2,689	958
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Forward commitments (mortgage) [Member]
Investment securities available for sale:
Trading assets	0	403
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	$ 1,732	$ 0

Fair Value Measurements, Asse76

Fair Value Measurements, Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale Securities [Member]
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Beginning Balance	$ 200	$ 200
Total net gains included in other comprehensive income
Ending Balance	200	200
Fair Value, Net Derivative Asset (Liability Measure on Recurring Basis, Unobservable Input Reconciliation On Net Losses Included in Income [Abstract]
Mortgage derivative loss	0	0
Derivatives [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	1,361	(488)
Fair Value, Net Derivative Asset (Liability Measure on Recurring Basis, Unobservable Input Reconciliation On Net Losses Included in Income [Abstract]
Mortgage derivative loss	(404)	1,849
Ending Balance	$ 957	$ 1,361

Fair Value Measurements, Asse77

Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Mortgage servicing rights	$ 59,414		$ 61,341
Mortgage Servicing Rights (MSR) Impairment (Recovery)	(909)	$ (243)
Fair Value, Inputs, Level 2 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	129,398		124,915
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Loans held for sale	129,398		124,915
market valuation adjustment, loans held for sale	0		(155)
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Impaired loans	84,664		41,891
Provision for Credit Losses, Impaired Loans	(15,097)		(7,796)
Mortgage servicing rights	61,410		70,686
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ 909		$ (425)

Fair Value Measurements, Fair V

Fair Value Measurements, Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Financial assets
Cash and due from banks		$ 287,183	$ 374,921
Interest-bearing deposits in other financial institutions		68,025	79,764
Federal funds sold and securities purchased under agreements to resell		20,200	19,000
Investment securities held to maturity		1,176,821	1,168,230
Investment securities held to maturity, fair value		1,204,345	1,184,442
Investment securities available for sale		4,905,841	4,967,414
FHLB and Federal Reserve Bank stocks		181,853	147,240
Loans held for sale		128,339	124,915
Loans, net		18,949,870	18,440,079
Derivatives (trading and other assets)		53,087	32,192
Financial liabilities
Short-term funding		1,417,408	834,416
Long-term funding	[1]	2,861,316	2,676,164
Derivatives (trading and other liabilities)		55,223	33,430
Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and due from banks		287,183	374,921
Cash and due from banks, Fair Value		287,183	374,921
Interest-bearing deposits in other financial institutions		68,025	79,764
Interest-bearing deposits in other financial institutions, fair value		68,025	79,764
Federal funds sold and securities purchased under agreements to resell		20,200	19,000
Federal funds sold and securities purchased under agreements to resell, fair value		20,200	19,000
Investment securities available for sale		2,605	2,566
Investment securities available for sale, at fair value		2,605	2,566
Fair Value, Inputs, Level 2 [Member]
Financial assets
Investment securities held to maturity		1,176,821	1,168,230
Investment securities held to maturity, fair value		1,204,345	1,184,442
Investment securities available for sale		4,903,036	4,964,648
Investment securities available for sale, at fair value		4,903,036	4,964,648
FHLB and Federal Reserve Bank stocks		181,853	147,240
Federal Home Loan Bank and Federal Reserve Bank stocks, fair value		181,853	147,240
Loans held for sale		128,339	124,915
Loans held for sale, fair value		129,398	124,915
Bank owned life insurance		580,583	583,019
Bank owned life insurance, fair value		580,583	583,019
Derivatives (trading and other assets)		55,315	34,907
Derivatives (trading and other assets), fair value		55,315	34,907
Financial liabilities
Brokered CDs and other time deposits		1,568,042	1,562,802
Brokered CDs and other time deposits, fair value		1,576,714	1,564,464
Short-term funding		1,417,408	834,416
Short-term funding, fair value		1,417,408	834,416
Long-term funding		2,861,316	2,676,164
Long-term funding, fair value		2,925,447	2,728,112
Standby letters of credit		2,746	2,954
Standby letters of credit, fair value		2,746	2,954
Derivatives (trading and other liabilities)		57,451	36,145
Derivatives (trading and other liabilities), fair value		57,451	36,145
Fair Value, Inputs, Level 3 [Member]
Financial assets
Investment securities available for sale		200	200
Investment securities available for sale, at fair value		200	200
Loans, net		18,949,870	18,440,079
Loans, net, fair value		19,025,680	18,389,832
Derivatives (trading and other assets)		2,689	1,361
Derivatives (trading and other assets), fair value		2,689	1,361
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts		19,117,418	19,444,863
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, fair value		19,117,418	19,444,863
Derivatives (trading and other liabilities)		1,732	0
Derivatives (trading and other liabilities), fair value		$ 1,732	$ 0
[1]	During the first quarter of 2016, the Corporation adopted a new accounting standard related to simplifying the presentation of debt issuance costs. Under this new accounting standard, debt issuance costs are still capitalized; however, they are reflected on the balance sheet with the related debt issued rather than within other assets. All prior periods have been restated to reflect this change in presentation. See Note 3 for additional information on this new accounting standard.

Fair Value Measurements (Detail

Fair Value Measurements (Details Textuals) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair Value Measurements (Textuals) [Abstract]
Other real estate owned measured at fair value	$ 3	$ 11
Write down of Other Real Estate Owned	1	3
Commitment on standby letters of credit	$ 279	$ 297
Fair Value of Assets and Liabilities [Line Items]
Closing ratio	89.00%
Weighted average discount rate	9.60%
Weighted average constant prepayment rate	15.20%
Maximum [Member]
Fair Value of Assets and Liabilities [Line Items]
Weighted average discount rate	15.00%
Minimum [Member]
Fair Value of Assets and Liabilities [Line Items]
Weighted average discount rate	10.00%

Retirement Plans, Components of

Retirement Plans, Components of Net Periodic Benefit Cost for the Pension and Postretirement Tables (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Retirement Plans Textuals [Abstract]
Defined Benefit Plan, Age of Eligibility of Plan	55 years
Defined Benefit Plan, Service Period for Eligibility in Plan	5 years
Pension Plan [Member]
Net period benefit cost for the pension and postretirement plans
Service cost	$ 1,725	$ 3,063
Interest cost	1,780	1,642
Expected return on plan assets	(5,065)	(5,350)
Prior service cost	13	13
Actuarial (gain) loss	482	532
Total net pension cost	(1,065)	(100)
Other Postretirement Benefit Plan [Member]
Net period benefit cost for the pension and postretirement plans
Interest cost	36	35
Total net pension cost	$ 36	$ 35

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Income Statement Data Abstract
Net interest income	$ 171,987	$ 167,813
Noninterest income	83,192	79,813
Total income	255,179	247,626
Provision for credit losses	20,000	4,500
Noninterest expense	173,971	173,992
Income before income taxes	61,208	69,134
Income tax expense	18,674	22,462
Net income	$ 42,534	$ 46,672
Return on average allocated capital (ROCET1)	8.60%	10.20%
Segment Balance Sheet Data
Average earning assets	$ 25,272,373	$ 24,148,026
Average loans	18,922,830	17,815,115
Average deposits	20,575,174	19,055,196
Average allocated capital (CET1)	1,896,481	1,804,217
Operating Segments [Member] | Corporate and Commercial Specialty
Segment Income Statement Data Abstract
Net interest income	79,164	75,691
Noninterest income	11,613	12,613
Total income	90,777	88,304
Provision for credit losses	12,739	9,526
Noninterest expense	34,403	34,460
Income before income taxes	43,635	44,318
Income tax expense	14,579	15,368
Net income	$ 29,056	$ 28,950
Return on average allocated capital (ROCET1)	11.30%	12.50%
Segment Balance Sheet Data
Average earning assets	$ 9,720,028	$ 9,218,844
Average loans	9,711,221	9,210,992
Average deposits	5,918,341	5,421,541
Average allocated capital (CET1)	1,031,659	942,764
Operating Segments [Member] | Community, Consumer, and Business
Segment Income Statement Data Abstract
Net interest income	85,605	86,357
Noninterest income	63,748	65,344
Total income	149,353	151,701
Provision for credit losses	6,142	7,071
Noninterest expense	121,295	118,373
Income before income taxes	21,916	26,257
Income tax expense	7,670	9,190
Net income	$ 14,246	$ 17,067
Return on average allocated capital (ROCET1)	9.10%	10.70%
Segment Balance Sheet Data
Average earning assets	$ 9,120,319	$ 8,525,399
Average loans	9,119,020	8,525,399
Average deposits	11,100,195	10,522,618
Average allocated capital (CET1)	627,211	647,375
Operating Segments [Member] | Risk Management and Shared Services
Segment Income Statement Data Abstract
Net interest income	7,218	5,765
Noninterest income	7,831	1,856
Total income	15,049	7,621
Provision for credit losses	1,119	(12,097)
Noninterest expense	18,273	21,159
Income before income taxes	(4,343)	(1,441)
Income tax expense	(3,575)	(2,096)
Net income	$ (768)	$ 655
Return on average allocated capital (ROCET1)	(5.00%)	(1.10%)
Segment Balance Sheet Data
Average earning assets	$ 6,432,026	$ 6,403,783
Average loans	92,589	78,724
Average deposits	3,556,638	3,111,037
Average allocated capital (CET1)	$ 237,611	$ 214,078

Accumulated Other Comprehensi82

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (32,616)
Personnel expense	(101,398)	$ (100,152)
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	(1,572)	0
Total other comprehensive income (loss)	34,783	29,650
Ending Balance	2,167
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(32,616)	(4,850)
Other comprehensive income (loss) before reclassifications	60,422	47,418
Investment securities gain, net	(3,098)
Personnel expense	495	545
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	(1,572)
Income tax (expense) benefit	(21,464)	(18,313)
Total other comprehensive income (loss)	34,783	29,650
Ending Balance	2,167	24,800
Investment Securities Available For Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	459	18,512
Other comprehensive income (loss) before reclassifications	60,422	47,418
Investment securities gain, net	(3,098)
Personnel expense	0	0
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	(1,572)
Income tax (expense) benefit	(21,275)	(18,105)
Total other comprehensive income (loss)	34,477	29,313
Ending Balance	34,936	47,825
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(33,075)	(23,362)
Other comprehensive income (loss) before reclassifications	0	0
Investment securities gain, net	0
Personnel expense	495	545
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	0
Income tax (expense) benefit	(189)	(208)
Total other comprehensive income (loss)	306	337
Ending Balance	$ (32,769)	$ (23,025)