Associated Banc-Corp (ASB) 10-Q 26 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 24, 2018
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	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		165,782,364
Entity Emerging Growth Company	false
Entity Small Business	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 374,168	$ 483,666
Interest-bearing deposits in other financial institutions	147,848	199,702
Federal funds sold and securities purchased under agreements to resell	24,325	32,650
Investment securities held to maturity, at amortized cost	2,661,755	2,282,853
Investment securities available for sale, at fair value	4,054,197	4,043,446
Federal Home Loan Bank and Federal Reserve Bank stocks, at cost	220,825	165,331
Residential loans held for sale	134,361	85,544
Commercial loans held for sale	30,452	0
Loans	22,867,112	20,784,991
Allowance for loan losses	(236,250)	(265,880)
Loans, net	22,630,861	20,519,111
Bank and corporate owned life insurance	661,009	591,057
Tax credit and other investments	132,355	147,099
Trading assets	140,328	69,675
Premises and equipment, net	358,926	330,963
Goodwill	1,168,922	976,239
Mortgage servicing rights, net	67,872	58,384
Other intangible assets, net	78,069	15,580
Other assets	602,730	482,294
Total assets	33,489,002	30,483,594
Liabilities and Stockholders’ Equity
Noninterest-bearing demand deposits	5,421,270	5,478,416
Interest-bearing deposits	19,410,342	17,307,546
Total deposits	24,831,612	22,785,962
Federal funds purchased and securities sold under agreements to repurchase	166,556	324,815
Commercial paper	43,604	67,467
FHLB advances	3,332,655	3,184,168
Other long-term funding	795,215	497,282
Trading liabilities	138,940	67,660
Accrued expenses and other liabilities	383,381	318,797
Total liabilities	29,691,963	27,246,151
Stockholders’ Equity
Preferred equity	256,716	159,929
Common stock	1,752	1,618
Surplus	1,834,017	1,454,188
Retained earnings	1,977,925	1,819,230
Accumulated other comprehensive income (loss)	(135,520)	(62,758)
Treasury stock, at cost	(137,852)	(134,764)
Total common equity	3,540,322	3,077,514
Total stockholders’ equity	3,797,038	3,237,443
Total liabilities and stockholders’ equity	$ 33,489,002	$ 30,483,594
Preferred shares issued	264,458	165,000
Preferred shares authorized (par value $1.00 per share)	750,000	750,000
Common shares issued	175,202,679	161,751,975
Common shares authorized (par value $0.01 per share)	250,000,000	250,000,000
Treasury shares of common stock	5,909,467	8,908,448

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred shares, par value	$ 1	$ 1
Common shares, par value	$ 0.01	$ 0.01

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Income
Interest and fees on loans	$ 249,649	$ 196,972	$ 716,329	$ 554,867
Interest and dividends on investment securities:
Taxable	29,895	24,162	90,622	71,295
Tax-exempt	11,883	8,268	31,883	24,540
Other interest	4,036	2,492	9,366	5,581
Total interest income	295,464	231,894	848,201	656,283
Interest Expense
Interest on deposits	50,116	27,778	121,959	65,882
Interest on Federal funds purchased and securities sold under agreements to repurchase	504	768	1,564	2,107
Interest on other short-term funding	38	70	150	239
Interest on FHLB advances	19,318	8,612	53,720	20,209
Interest on long-term funding	6,095	4,544	15,183	13,632
Total interest expense	76,072	41,772	192,576	102,068
Net Interest Income	219,392	190,122	655,625	554,215
Provision for credit losses	(5,000)	5,000	(1,000)	26,000
Net interest income after provision for credit losses	224,392	185,122	656,625	528,215
Noninterest Income
Mortgage banking, net	4,012	6,585	16,640	16,191
Capital markets, net	5,099	4,610	15,189	12,535
Bank and corporate owned life insurance	3,540	6,580	10,705	13,094
Asset gains (losses), net(a)	(1,037)	(16)	1,353	(716)
Investment securities gains (losses), net	30	3	(1,985)	359
Other	2,802	2,254	7,529	6,746
Total noninterest income	88,300	85,895	271,522	248,136
Noninterest Expense
Personnel	124,476	108,098	366,141	321,946
Occupancy	14,519	12,294	44,947	40,345
Technology	17,563	15,233	54,730	45,126
Equipment	5,838	5,232	17,347	15,951
Business development and advertising	8,213	7,764	21,973	20,751
Legal and professional	5,476	6,248	17,173	16,125
Card issuance and loan costs	3,677	3,330	10,154	8,924
Foreclosure / OREO expense, net	950	906	2,694	3,593
FDIC assessment	7,750	7,800	24,250	23,800
Other intangible amortization	2,233	450	5,926	1,459
Acquisition related costs(b)		0		0
Other	11,445	10,072	33,318	29,413
Total noninterest expense	204,413	177,427	628,636	527,434
Income before income taxes	108,279	93,590	299,510	248,917
Income tax expense	22,349	28,589	54,932	69,663
Net income	85,929	65,001	244,578	179,254
Preferred stock dividends	2,409	2,339	7,077	7,008
Net income available to common equity	$ 83,521	$ 62,662	$ 237,501	$ 172,246
Earnings per common share:
Basic	$ 0.49	$ 0.41	$ 1.40	$ 1.13
Diluted	$ 0.48	$ 0.41	$ 1.38	$ 1.11
Average common shares outstanding:
Basic	170,516	150,565	168,249	150,983
Diluted	172,802	152,968	170,876	153,782
Insurance Commissions and Fees
Noninterest Income
Service charges on deposit account fees	$ 21,636	$ 19,815	$ 68,279	$ 62,288
Deposit Account
Noninterest Income
Service charges on deposit account fees	16,904	16,268	49,714	48,654
Card-Based and Loan Fees
Noninterest Income
Service charges on deposit account fees	14,090	12,619	41,899	38,848
Fiduciary and Trust
Noninterest Income
Service charges on deposit account fees	14,140	12,785	40,946	37,066
Brokerage Commission and Fees
Noninterest Income
Service charges on deposit account fees	7,084	4,392	21,253	13,071
Acquisition-related Costs [Member]
Noninterest Income
Asset gains (losses), net(a)	(1,000)		(2,000)
Operating Segments [Member] | Risk Management and Shared Serivies [Member]
Interest Expense
Net Interest Income	14,770	15,951	47,770	47,552
Provision for credit losses	(21,512)	(9,545)	(49,081)	(21,866)
Noninterest Income
Total noninterest income	2,183	5,750	8,257	12,822
Noninterest Expense
Acquisition related costs(b)	2,271		29,983
Total noninterest expense	22,932	17,505	100,445	49,276
Income before income taxes	6,599	4,604	(22,488)	(1,999)
Income tax expense	1,390	(2,217)	(10,416)	(15,500)
Net income	$ 5,209	$ 6,821	$ (12,072)	$ 13,501

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 85,929	$ 65,001	$ 244,578	$ 179,254
Investment securities available for sale
Net unrealized gains (losses)	(21,345)	(1,986)	(82,099)	16,384
Net unrealized gain (loss) on available for sale securities transferred to held to maturity securities	0	0	0	(14,738)
Amortization of net unrealized gain (loss) on available for sale securities transferred to held to maturity securities	(52)	76	(684)	(2,499)
Reclassification adjustment for net losses (gains) realized in net income(1)	(30)	0	1,985	0
Reclassification from OCI due to change in accounting principle	0	0	(84)	0
Reclassification of certain tax effects from OCI	0	0	(8,419)	0
Income tax (expense) benefit	5,456	734	20,796	328
Other comprehensive income (loss) on investment securities available for sale	(15,971)	(1,176)	(68,505)	(525)
Defined benefit pension and postretirement obligations
Amortization of prior service cost	37	38	(112)	113
Amortization of actuarial loss (gains)	(551)	(621)	1,480	(1,596)
Reclassification of certain tax effects from OCI	0	0	(5,235)	0
Income tax (expense) benefit	174	225	(390)	567
Other comprehensive income (loss) on pension and postretirement obligations	340	358	(4,257)	916
Total other comprehensive income (loss)	15,631	818	72,762	(391)
Comprehensive income	$ 70,298	$ 64,183	$ 171,816	$ 179,645

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Equity	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2016	$ 3,091,312	$ 159,929	$ 1,630	$ 1,459,498	$ 1,695,764	$ (54,679)	$ (170,830)
Comprehensive income:
Net income	179,254	0	0	0	179,254	0	0
Other comprehensive income	(391)	0	0	0	0	391	0
Comprehensive income	179,645
Common stock issued:
Stock-based compensation plans, net	22,460	0	0	1,952	(20,768)	0	41,276
Purchase of common stock returned to authorized but unissued	(37,031)	0	(15)	(37,016)	0	0	0
Purchase of treasury stock	(8,613)	0	0	0	0	0	(8,613)
Cash dividends:
Common stock ($0.36 per share in 2017 and $0.45 per share in 2018)	(55,058)	0	0	0	(55,058)	0	0
Preferred stock	(7,008)	0	0	0	(7,008)	0	0
Issuance of preferred stock	0
Stock-based compensation expense, net	16,860	0	0	16,860	0	0	0
Other	1,034	0	0	1,034	0	0	0
Ending balance at Sep. 30, 2017	3,203,601	159,929	1,615	1,442,328	1,792,184	(54,288)	(138,167)
Beginning balance at Dec. 31, 2017	3,237,443	159,929	1,618	1,454,188	1,819,230	(62,758)	(134,764)
Comprehensive income:
Net income	244,578	0	0	0	244,578	0	0
Other comprehensive income	72,762	0	0	0	0		0
AOCI Loss Net of ASU Adoption and Tax	(59,024)					(59,024)
Adoption of new accounting standards	(13,738)	0	0	0	0	(13,738)	0
Comprehensive income	171,816
Common stock issued:
Stock-based compensation plans, net	17,393	0	0	3,134	(15,737)	0	29,996
Acquisitions	488,408	0	137	396,975	0	0	91,296
Purchase of common stock returned to authorized but unissued	(33,075)	0	(14)	(33,061)	0	0	0
Purchase of treasury stock	(124,380)	0	0	0	0	0	(124,380)
Cash dividends:
Common stock ($0.36 per share in 2017 and $0.45 per share in 2018)	(77,431)	0	0	0	(77,431)	0	0
Preferred stock	(7,077)	0	0	0	(7,077)	0	0
Issuance of preferred stock	97,315	97,315	0	0	0	0	0
Redemption of preferred stock	(646)	(528)	0	0	(118)	0	0
Common stock warrants exercised	0	0	11	(11)	0	0	0
Stock-based compensation expense, net	12,792	0	0	12,792	0	0	0
Tax Act Reclassification	13,654	0	0	0	13,654	0	0
Change in accounting principle	84	0	0	0	84	0	0
Other	742	0	0	0	742	0	0
Ending balance at Sep. 30, 2018	$ 3,797,038	$ 256,716	$ 1,752	$ 1,834,017	$ 1,977,925	$ (135,520)	$ (137,852)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Common Stock, Dividends, Per Share, Cash Paid	$ 0.45	$ 0.36

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 85,929	$ 65,001	$ 244,578	$ 179,254
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(5,000)	5,000	(1,000)	26,000
Depreciation and amortization			36,273	35,054
Addition to (recovery of) valuation allowance on mortgage servicing rights, net			(669)	286
Amortization of mortgage servicing rights			7,143	7,635
Amortization of other intangible assets	2,233	450	5,926	1,459
Amortization and accretion on earning assets, funding, and other, net			10,468	27,230
Net amortization of tax credit investments			14,388	14,685
Losses (gains) on sales of investment securities, net			1,985	(359)
Asset (gains) losses, net	1,037	16	(1,353)	716
(Gain) loss on mortgage banking activities, net			(15,412)	(3,762)
Mortgage loans originated and acquired for sale			(847,619)	(466,135)
Proceeds from sales of mortgage loans held for sale			826,929	551,697
Pension contribution			(41,877)	(6,242)
(Increase) decrease in interest receivable			(14,791)	(9,765)
Increase (decrease) in interest payable			4,671	3,410
Increase (decrease) in cash collateral			21,932	1,396
Net change in other assets and other liabilities			51,171	(46,278)
Net cash provided by operating activities			302,743	316,281
CASH FLOWS FROM INVESTING ACTIVITIES
Net increase in loans			(322,589)	(991,334)
Purchases of:
Available for sale securities			(737,580)	(701,080)
Held to maturity securities			(553,258)	(121,596)
Federal Home Loan Bank and Federal Reserve Bank stocks			(267,432)	(195,356)
Premises, equipment, and software, net of disposals			(42,941)	(32,925)
Proceeds from:
Sales of available for sale securities	108,000		601,130	0
Sales of held to maturity securities			0	16,059
Sale of Federal Home Loan Bank and Federal Reserve Bank stocks			231,964	162,911
Prepayments, calls, and maturities of available for sale investment securities			487,858	551,962
Prepayments, calls, and maturities of held to maturity investment securities			168,125	151,565
Sales, prepayments, calls, and maturities of other assets			24,243	10,833
Net Change in Tax Credit Investments			(32,690)	(35,027)
Net cash (paid) received in acquisition			59,472	(217)
Net cash used in investing activities			(383,698)	(1,184,205)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in deposits			204,700	445,003
Net increase (decrease) in short-term funding			(528,285)	(65,418)
Net increase (decrease) in short-term FHLB advances			121,000	38,000
Repayment of long-term FHLB advances			(1,900,012)	(115,017)
Proceeds from long-term FHLB advances			1,841,776	500,000
Proceeds from issuance of long-term funding			300,000	0
Proceeds from issuance of preferred shares			97,315	0
Proceeds from issuance of common stock for stock-based compensation plans			17,393	22,460
Redemption of preferred shares			(646)	0
Purchase of common stock returned to authorized but unissued			(33,075)	(37,031)
Purchase of treasury stock for tax withholding			(124,380)	(8,613)
Cash dividends on common stock			(77,431)	(55,058)
Cash dividends on preferred stock			(7,077)	(7,008)
Net cash provided by (used in) financing activities			(88,722)	717,318
Net increase (decrease) in cash, cash equivalents, and restricted cash			(169,677)	(150,606)
Cash, cash equivalents, and restricted cash at beginning of period			716,018	642,233	$ 642,233
Cash, cash equivalents, and restricted cash at end of period	546,341	491,627	546,341	491,627	$ 716,018
Supplemental disclosures of cash flow information:
Cash paid for interest			185,875	98,151
Cash paid for income taxes			17,335	61,959
Loans and bank premises transferred to other real estate owned			20,781	5,872
Capitalized mortgage servicing rights			7,826	4,822
Loans transferred into held for sale from portfolio, net			56,550	75,289
Fair value of assets acquired, including cash and cash equivalents	2,567,560	0	2,567,560	0
Fair value ascribed to goodwill and intangible assets	261,142	217	261,142	217
Fair value of liabilities assumed	2,340,294	0	2,340,294	0
Equity issued in acquisition			488,408	0
Restricted Cash	88,613	68,235	88,613	68,235
Cash and cash equivalents	$ 457,728	$ 423,392	$ 457,728	$ 423,392

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
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.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions Bank Mutual Acquisition On February 1, 2018, the Corporation completed its acquisition of Bank Mutual Corporation ("Bank Mutual") in a stock transaction valued at approximately $482 million . Bank Mutual was a diversified financial services company headquartered in Milwaukee, Wisconsin. The merger resulted in a combined company with a larger market presence in markets the Corporation currently operates in, as well as expansion into nearly a dozen new markets. The merger is also expected to provide significant efficiency opportunities and economies of scale associated with a larger financial institution. Under the terms of the Agreement and Plan of Merger dated July 20, 2017 (the "Merger Agreement"), Bank Mutual’s shareholders received 0.422 shares of the Corporation's common stock for each share of Bank Mutual common stock. The Corporation issued approximately 19.5 million shares for a total deal value of approximately $482 million based on the closing sale price of a share of common stock of the Corporation on January 31, 2018. The Corporation completed the conversion of Bank Mutual in the second quarter of 2018. The banking subsidiary of Bank Mutual merged with and into Associated Bank, N.A. on June 24, 2018. The acquisition of Bank Mutual constituted a business combination. The merger has been accounted for using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed, and consideration exchanged were recorded at estimated fair value on the acquisition date. The determination of estimated fair values required management to make certain estimates that are subjective in nature and may require adjustments upon the availability of new information regarding facts and circumstances which existed at the date of acquisition (i.e., appraisals) for up to a year following the acquisition. The Corporation continues to review information relating to events or circumstances existing at the acquisition date. Management anticipates that this review could result in adjustments to the acquisition date valuation amounts presented herein but does not anticipate that these adjustments will be material. Goodwill related to the Bank Mutual acquisition increased $6 million during the second quarter of 2018 and an additional $2 million during the third quarter of 2018 to $175 million . Upon review of information relating to events and circumstances existing at the acquisition date, and in accordance with applicable accounting guidance, the Corporation remeasured select previously reported fair value amounts. Based on updated appraisal information, the fair value of premises and equipment decreased by $6 million and $2 million during the second and third quarters of 2018, respectively. Additionally, during the second quarter of 2018, the fair value of loans was increased by less than $1 million due to an updated appraisal and other adjustments. Goodwill created by the acquisition of Bank Mutual is not tax deductible. See Note 8 for additional information on goodwill, as well as the carrying amount and amortization of core deposit and other intangible assets related to the Bank Mutual acquisition. The following table presents the estimated fair values of the assets acquired and liabilities assumed as of the acquisition date related to Bank Mutual. Purchase Accounting Adjustments February 1, 2018 ($ in Thousands) Assets Cash and cash equivalents $ — $ 78,052 Investment securities (6,238 ) 452,867 Federal Home Loan Bank stock, at cost — 20,026 Loans (48,043 ) 1,875,877 Premises and equipment, net 2,930 42,689 Bank owned life insurance (24 ) 65,390 Goodwill 175,499 Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet) 58,100 58,100 Other real estate owned (included in other assets on the face of the Consolidated Balance Sheet) 199 4,848 Others assets $ 7,054 $ 47,158 Total assets $ 2,820,506 Liabilities Deposits $ 2,498 $ 1,840,950 Other borrowings 1,875 431,886 Other liabilities $ 4,487 $ 65,982 Total liabilities $ 2,338,818 Total consideration paid $ 481,688 The following is a description of the methods used to determine the fair value of significant assets and liabilities presented on the balance sheet above. Loans: Fair values for loans were based on a discounted cash flow methodology that considered factors including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan, amortization status and current discount rates. Loans were grouped together according to similar characteristics when applying various valuation techniques. Core deposit intangible ("CDI"): This intangible asset represents the value of the relationships with deposit customers. The fair value was estimated based on a discounted cash flow methodology that gave appropriate consideration to expected customer attrition rates, net maintenance cost of the deposit base, alternative cost of funds, and the interest costs associated with customer deposits. The CDI is being amortized on a straight-line basis over 10 years . Time deposits: The fair values for time deposits are estimated using a discounted cash flow calculation that applies interest rates currently being offered to the contractual interest rates on such time deposits. Federal Home Loan Bank ("FHLB") borrowings: The fair values of FHLB advances are estimated based on quoted market prices for the instrument if available, or for similar instruments if not available, or by using discounted cash flow analyses, based on current incremental borrowing rates for similar types of instruments. See Note 13 for additional information on fair value measurements. Other Acquisitions During the second quarter of 2018, the Corporation completed the acquisition of Anderson Insurance & Investment Agency, Inc. ("Anderson"), an independent insurance agency based in Minneapolis, Minnesota. Anderson adds a range of complementary services and significant expertise in workers' compensation and executive risk management services. The transaction was valued at approximately $10 million . As a result of the acquisition, the Corporation recorded goodwill of approximately $7 million and added approximately $3 million of other intangibles related to customer relationships associated with the Anderson acquisition. The other intangibles related to the acquisition are being amortized on a straight-line basis over 7 years . See Note 8 for more information on goodwill and other intangible assets. During the first quarter of 2018, the Corporation completed the acquisition of Diversified Insurance Solutions ("Diversified"). The acquisition improved Associated Benefits and Risk Consulting's ability to achieve greater scale in the Metro Milwaukee market and to further expand its Wisconsin employee benefits and property and casualty market position and capabilities. The transaction was valued at approximately $19 million . As a result of the acquisition, the Corporation recorded goodwill of approximately $10 million and other intangibles of approximately $8 million . The other intangibles related to the acquisition are being amortized on a straight-line basis over 10 years

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The accounting and reporting policies of the Corporation conform to U.S. generally accepted accounting principles and to general practice within the financial services industry. A discussion of these policies can be found in Note 1 Summary of Significant Accounting Policies section included in the Corporation’s 2017 Annual Report on Form 10-K. There have been two changes to the Corporation's significant accounting policies since December 31, 2017 . Business combinations The Corporation accounts for its acquisitions using the purchase accounting method. Purchase accounting requires the total purchase price to be allocated to the estimated fair values of assets acquired and liabilities assumed, including certain intangible assets that must be recognized. Typically, this allocation results in the purchase price exceeding the fair value of net assets acquired, which is recorded as goodwill. Core deposit intangibles are a measure of the value of checking, money market and savings deposits acquired in business combinations accounted for under the purchase method. Core deposit intangibles and other identified intangibles with finite useful lives are amortized using the straight line method over their estimated useful lives of up to ten years. Loans that the Corporation acquires in connection with acquisitions are recorded at fair value with no carryover of the related allowance for credit losses. Fair value of the loans involves estimating the amount and timing of principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loan when there is a reasonable expectation about the amount and timing of such cash flows. If a reasonable expectation on the amount or timing of such cash flows can't be determined, accretion of the fair value discount for nonperforming loans will be recognized using the cost recovery method of accounting. The difference between contractually required payments at acquisition and the cash flows expected to be collected at acquisition is referred to as the non-accretable discount. The non-accretable discount includes estimated future credit losses expected to be incurred over the life of the loan. Subsequent decreases to the expected cash flows will require the Corporation to evaluate the need for an additional allowance for credit losses. Subsequent improvement in expected cash flows will result in the reversal of a corresponding amount of the non-accretable discount which the Corporation will then reclassify as accretable discount that will be recognized into interest income over the remaining life of the loan. The Corporation accounts for performing loans acquired in business combinations using the contractual cash flows method of recognizing discount accretion based on the acquired loans’ contractual cash flows. Purchased performing loans are recorded at fair value, including credit, interest, and liquidity discounts. The fair value discount is accreted as an adjustment to yield over the estimated lives of the loans. There is no allowance for loan losses established at the acquisition date for purchased performing loans. A provision for loan losses is recorded for any further deterioration in these loans subsequent to the acquisition. Revenue Recognition The Corporation recognizes revenue in accordance with ASC 606, "Revenue from Contracts with Customers." ASC 606 requires the Corporation to follow a five step process: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation. Revenue recognition under ASC 606 depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the goods or services. New Accounting Pronouncements Adopted Standard Description Date of adoption Effect on financial statements ASU 2018-02 Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income The FASB issued an amendment to allow a reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendments in this update are effective for all entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption of the update was permitted and should be applied in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate related to the Tax Cuts and Jobs Act of 2017 is recognized. 1st Quarter 2018 The Corporation has elected to early adopt this amendment. During the first quarter of 2018, the Corporation reclassified approximately $14 million from accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act. No material impact on results of operations, financial position, or liquidity. See Consolidated Statements of Comprehensive Income and the Statement of Changes in Stockholders' Equity. ASU 2017-12 Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities The FASB issued an amendment to better align a company’s financial reporting for hedging activities with the economic objectives of those activities for both financial (e.g., interest rate) and commodity risks. The provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes. It also contains targeted improvements to simplify the application of hedge accounting guidance. This amendment is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Entities should apply the amendment on a modified retrospective transition method in which the cumulative effect of the change will be recognized within equity in the consolidated balance sheet as of the date of adoption. Early adoption was permitted, including in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes the interim period. 1st Quarter 2018 The Corporation has elected to early adopt this amendment. No material impact on results of operations, financial position, or liquidity. See Note 10 for expanded disclosures. ASU 2017-07 Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost The FASB issued an amendment to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost, including a requirement that employers disaggregate the service cost component from the other components of net benefit cost. In addition, the amendments provide explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allow only the service cost component of net benefit cost to be eligible for capitalization. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented and prospectively only for the capitalization component. Early adoption is permitted, but should be within the first interim period if interim financial statements are issued. 1st Quarter 2018 No impact on results of operations, financial position, or liquidity. The update required retrospective restatement. For the full year 2017, the Corporation reclassified approximately $9 million from personnel expense to other noninterest expense for the non-service cost components of net periodic pension cost and net periodic postretirement benefit cost. See Note 14 for expanded disclosure. ASU 2017-01 Business Combinations (Topic 805): Clarifying the Definition of a Business The FASB issued amendments to clarify the definition of a business in order to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets versus businesses. The new standard narrows the definition of a business by adding three principal clarifications if: (1) substantially all the fair value of the gross assets in the asset group is concentrated in either a single identifiable asset or group of similar identifiable assets the transaction does not involve a business, (2) the asset group does not include a minimum of an input and a substantive process, it does not represent a business, and (3) the integrated set of activities (including its inputs and processes) does not create, or have the ability to create, goods or services to customers, investment income (e,g. dividends or interest) or other revenues, then it is not a business. The overall intention is to provide consistency in applying the guidance, reduce the costs of application, and make the definition of a business more operable. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment prospectively on or after the effective date. 1st Quarter 2018 No material impact on results of operations, financial position, or liquidity. ASU 2016-18 Statement of Cash Flows (Topic 230): Restricted Cash The FASB issued an amendment to improve GAAP by providing guidance on the presentation of restricted cash or restricted cash equivalents in the statement of cash flows, in order to reduce diversity in practice. The amendment requires that a statement of cash flow explain the change during the period in the total cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included in cash and cash equivalents when reconciling the beginning and end of period total amounts shown on the statement of cash flow. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented. Early adoption is permitted, including in an interim period. 1st Quarter 2018 No impact on results of operations, financial position, or liquidity. See Consolidated Statements of Cash Flows. Standard Description Date of adoption Effect on financial statements ASU 2016-16 Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory The FASB issued an amendment requiring an entity to recognize income tax consequences on an intra-entity transfer of an asset other than inventory at the time the transaction occurs. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment by means of a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. Early adoption is permitted for all entities in the first interim period if an entity issues interim financial statements. 1st Quarter 2018 No material impact on results of operations, financial position, or liquidity. ASU 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments The FASB issued an amendment to provide clarification on where to classify cash flows involving certain cash receipts and cash payments. Under the new guidance, cash payments for debt prepayment or debt extinguishment costs should be classified as cash outflows from financing activities. The new guidance also details the specific classification of contingent consideration cash payments made after a business combination depending on the timing of payments. Lastly, cash proceeds received from corporate owned life insurance policies (including bank owned life insurance) should be classified as cash inflows from investing, while the cash payments for the premiums may be classified as cash outflows from investing, operating, or a combination of both. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented. Early adoption is permitted, including in an interim period; however, all of the amendments must be adopted in the same period. 1st Quarter 2018 No material impact on results of operations, financial position, or liquidity. ASU 2016-01 Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The FASB issued an amendment to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. This amendment supersedes the guidance to classify equity securities with readily determinable fair values into different categories, requires equity securities to be measured at fair value with changes in the fair value recognized through net income, and simplifies the impairment assessment of equity investments without readily determinable fair values. The amendment requires public business entities that are required to disclose the fair value of financial instruments measured at amortized cost on the balance sheet to measure that fair value using the exit price notion. The amendment requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option. The amendment requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or in the accompanying notes to the financial statements. The amendment reduces diversity in current practice by clarifying that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity’s other deferred tax assets. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities are required to apply the amendment by means of a cumulative-effect adjustment as of the beginning of the fiscal year of adoption, with the exception of the amendment related to equity securities without readily determinable fair values, which should be applied prospectively to equity investments that exist as of the date of adoption. 1st Quarter 2018 The Corporation has adopted this amendment using the cumulative-effect adjustment as of the beginning of the fiscal year of adoption. No material impact on the result of operations, financial position or liquidity. In 2008, the Corporation received Visa Class B restricted shares as part of Visa’s initial public offering. Based on the existing transfer restriction and the uncertainty of the covered litigation, the approximately 119 thousand Class B shares remaining that the Corporation owned as of September 30, 2018 are carried at a zero cost basis. See Consolidated Statements of Comprehensive Income and Note 13 Fair Value Measurements. ASU 2014-09 Revenue from Contracts with Customers (Topic 606) The FASB issued an amendment to clarify the principles for recognizing revenue and to develop a common revenue standard. The standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that “an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.” In applying the revenue model to contracts within its scope, an entity should apply the following steps: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation. The standard applies to all contracts with customers except those that are within the scope of other topics in the FASB Codification. The standard also requires significantly expanded disclosures about revenue recognition. The amendment was originally to be effective for annual reporting periods beginning after December 15, 2016 (including interim reporting periods within those periods); however, in July 2015, the FASB approved a one year deferral of the effective date to December 31, 2017. 1st Quarter 2018 The Corporation chose to adopt this amendment using the modified retrospective approach with no material impact on the Corporation's results of operations, financial position, or liquidity. See Note 17 for expanded disclosure requirements.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2018
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 and unvested restricted stock awards) and common stock warrants. Presented below are the calculations for basic and diluted earnings per common share. For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 (In Thousands, except per share data) Net income $ 85,929 $ 65,001 $ 244,578 $ 179,254 Preferred stock dividends (2,409 ) (2,339 ) (7,077 ) (7,008 ) Net income available to common equity $ 83,521 $ 62,662 $ 237,501 $ 172,246 Common shareholder dividends (25,486 ) (18,149 ) (77,035 ) (54,726 ) Unvested share-based payment awards (128 ) (105 ) (396 ) (332 ) Undistributed earnings $ 57,907 $ 44,408 $ 160,070 $ 117,188 Undistributed earnings allocated to common shareholders 57,620 44,150 159,297 116,418 Undistributed earnings allocated to unvested share-based payment awards 288 258 772 770 Undistributed earnings $ 57,907 $ 44,408 $ 160,070 $ 117,188 Basic Distributed earnings to common shareholders $ 25,486 $ 18,149 $ 77,035 $ 54,726 Undistributed earnings allocated to common shareholders 57,620 44,150 159,297 116,418 Total common shareholders earnings, basic $ 83,106 $ 62,299 $ 236,332 $ 171,144 Diluted Distributed earnings to common shareholders $ 25,486 $ 18,149 $ 77,035 $ 54,726 Undistributed earnings allocated to common shareholders 57,620 44,150 159,297 116,418 Total common shareholders earnings, diluted $ 83,106 $ 62,299 $ 236,332 $ 171,144 Weighted average common shares outstanding 170,516 150,565 168,249 150,983 Effect of dilutive common stock awards 2,188 1,815 2,101 2,081 Effect of dilutive common stock warrants 98 588 526 718 Diluted weighted average common shares outstanding 172,802 152,968 170,876 153,782 Basic earnings per common share $ 0.49 $ 0.41 $ 1.40 $ 1.13 Diluted earnings per common share $ 0.48 $ 0.41 $ 1.38 $ 1.11 Anti-dilutive common stock options of approximately 1.4 million and 1.0 million for the three months ended September 30, 2018 and 2017 , respectively, and 1.4 million and 1.0 million for the nine months ended September 30, 2018 and 2017

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Stock-Based Compensation	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. Performance awards are based on performance goals of earnings per share and total shareholder return with vesting ranging from a minimum of 25% to a maximum of 150% of the target award. Performance awards are valued utilizing a Monte Carlo simulation model to estimate fair value of the awards at the grant date. 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 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 nine months of 2018 and full year 2017 . 2018 2017 Dividend yield 2.50 % 2.00 % Risk-free interest rate 2.60 % 2.00 % Weighted average expected volatility 22.00 % 25.00 % Weighted average expected life 5.75 years 5.5 years Weighted average per share fair value of options $4.47 $5.30 A summary of the Corporation’s stock option activity for the nine months ended September 30, 2018 is presented below. Stock Options Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (a) Outstanding at December 31, 2017 5,118,687 $ 18.02 6.48 $ 38,028 Granted 938,740 24.50 Assumed from Bank Mutual acquisition 370,051 14.35 Exercised (966,213 ) 16.57 Forfeited or expired (63,313 ) 25.17 Outstanding at September 30, 2018 5,397,952 $ 19.07 6.48 $ 37,423 Options Exercisable at September 30, 2018 3,253,556 $ 16.89 5.24 $ 29,649 (a) $ in Thousands 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 nine months ended September 30, 2018 , the intrinsic value of stock options exercised was approximately $10 million . For the nine months ended September 30, 2017 , the intrinsic value of the stock options exercised was $12 million . The total fair value of stock options vested was $4 million for both the nine months ended September 30, 2018 and September 30, 2017 . The Corporation recognized compensation expense for the vesting of stock options of $3 million for both the nine months ended September 30, 2018 and September 30, 2017 . Included in compensation expense for 2018 was less than $1 million of expense for the accelerated vesting of stock options granted to retirement eligible colleagues. At September 30, 2018 , the Corporation had approximately $5 million of unrecognized compensation expense related to stock options that is expected to be recognized over the remaining requisite service periods that extend through first quarter 2022 . The following table summarizes information about the Corporation’s restricted stock activity for the nine months ended September 30, 2018 . Restricted Stock Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2017 2,026,071 $ 19.68 Granted 592,371 24.72 Vested (568,441 ) 18.33 Forfeited (50,478 ) 22.25 Outstanding at September 30, 2018 1,999,523 $ 21.94 The Corporation amortizes the expense related to restricted stock awards as compensation expense over the vesting period specified in the grant's award agreement. Performance-based restricted stock awards granted during 2017 and 2018 will vest ratably over a three year period. Service-based restricted stock awards granted during 2017 and 2018 will vest ratably over a four year period. Expense for restricted stock awards issued of approximately $10 million was recorded for the nine months ended September 30, 2018 and $14 million was recorded for the nine months ended September 30, 2017 . Included in compensation expense for 2018 was approximately $1 million of expense for the accelerated vesting of restricted stock awards granted to retirement eligible colleagues. The Corporation had $21 million of unrecognized compensation costs related to restricted stock awards at September 30, 2018 , that is expected to be recognized over the remaining requisite service periods that extend through first quarter 2022 . 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

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2018
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”). A portion of the portfolio is also comprised of asset-backed securities backed by student loans made under the Federal Family Education Loan Program ("FFELP"). The amortized cost and fair values of securities available for sale and held to maturity were as follows. September 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,001 $ — $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 320,148 2,658 (6,132 ) 316,674 GNMA 2,259,538 — (79,528 ) 2,180,010 Private-label 1,022 — (4 ) 1,018 GNMA commercial mortgage-related securities 1,306,802 — (55,824 ) 1,250,978 FFELP asset backed securities 298,282 1,766 (101 ) 299,947 Other debt securities 3,000 — — 3,000 Other equity securities 1,573 — — 1,573 Total investment securities available for sale $ 4,191,366 $ 4,424 $ (141,593 ) $ 4,054,197 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,682,162 $ 1,216 $ (33,332 ) $ 1,650,046 Residential mortgage-related securities FNMA / FHLMC 95,603 162 (3,266 ) 92,499 GNMA 367,536 1,753 (15,337 ) 353,952 GNMA commercial mortgage-related securities 516,454 8,092 (26,026 ) 498,520 Total investment securities held to maturity $ 2,661,755 $ 11,223 $ (77,961 ) $ 2,595,017 December 31, 2017 Amortized Gross Gross Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,003 $ — $ (7 ) $ 996 Residential mortgage-related securities FNMA / FHLMC 457,680 9,722 (2,634 ) 464,768 GNMA 1,944,453 275 (31,378 ) 1,913,350 Private-label 1,067 — (8 ) 1,059 GNMA commercial mortgage-related securities 1,547,173 5 (33,901 ) 1,513,277 FFELP asset backed securities 144,322 867 (13 ) 145,176 Other debt securities 3,200 — (12 ) 3,188 Other equity securities 1,519 127 (14 ) 1,632 Total investment securities available for sale $ 4,100,417 $ 10,996 $ (67,967 ) $ 4,043,446 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,281,320 $ 13,899 $ (3,177 ) $ 1,292,042 Residential mortgage-related securities FNMA / FHLMC 40,995 398 (489 ) 40,904 GNMA 414,440 2,700 (6,400 ) 410,740 GNMA commercial mortgage-related securities 546,098 9,546 (15,756 ) 539,888 Total investment securities held to maturity $ 2,282,853 $ 26,543 $ (25,822 ) $ 2,283,574 The expected maturities of investment securities available for sale and held to maturity at September 30, 2018 are shown below. Expected maturities may 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 Amortized Cost Fair Value Amortized Cost Fair Value ($ in Thousands) Due in one year or less $ 2,001 $ 1,997 $ 48,561 $ 48,871 Due after one year through five years 2,000 2,000 188,337 186,335 Due after five years through ten years — — 385,908 377,705 Due after ten years — — 1,059,355 1,037,135 Total debt securities 4,001 3,997 1,682,162 1,650,046 Residential mortgage-related securities FNMA / FHLMC 320,148 316,674 95,603 92,499 GNMA 2,259,538 2,180,010 367,536 353,952 Private-label 1,022 1,018 — — GNMA commercial mortgage-related securities 1,306,802 1,250,978 516,454 498,520 FFELP asset backed securities 298,282 299,947 — — Equity securities 1,573 1,573 — — Total investment securities $ 4,191,366 $ 4,054,197 $ 2,661,755 $ 2,595,017 Ratio of Fair Value to Amortized Cost 96.7 % 97.5 % The proceeds from the sale of investment securities for the nine months ended September 30, 2018 and 2017 are shown below. Nine Months Ended September 30, 2018 2017 ($ in Thousands) Gross gains on available for sale securities $ 1,954 $ — Gross gains on held to maturity securities — 364 Total gains 1,954 364 Gross losses on available for sale securities (3,938 ) — Gross losses on held to maturity securities $ — $ (5 ) Total losses $ (3,938 ) $ (5 ) Investment securities gains (losses), net $ (1,985 ) $ 359 Proceeds from sales of investment securities $ 601,130 $ 16,059 During 2018, the Corporation executed a strategy to improve the yield on securities and increase interest income during the current and future calendar years. During the third quarter of 2018, the Corporation sold mortgage-related securities totaling approximately $108 million at a slight gain with all proceeds reinvested into higher-yielding securities. The taxable equivalent yield of the securities sold was 3.08% while the reinvestment was at 3.51% . During the first six months of 2018, the Corporation also sold $40 million of lower yielding GNMA commercial mortgage-related securities. In addition, on the acquisition date, the Corporation sold Bank Mutual's entire $ 453 million securities portfolio. The Corporation reinvested these funds into municipal securities. This strategy was completed during August 2018. During the first nine months of 2017, the Corporation sold approximately $ 16 million of municipal securities classified as held to maturity due to credit concerns stemming from budgetary pressure and continued credit rating deterioration concerns in the State of Illinois. Investment securities with a carrying value of approximately $3.7 billion and $3.1 billion at September 30, 2018 , and December 31, 2017 , respectively, were pledged to secure certain deposits or for other purposes as required or permitted by law. The following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position, at September 30, 2018 . Less than 12 months 12 months or more Total September 30, 2018 Number of Securities Unrealized Losses Fair Value Number of Securities Unrealized Losses Fair Value Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale U.S. Treasury securities — $ — $ — 1 $ (4 ) $ 997 $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 18 (583 ) 60,527 14 (5,549 ) 172,119 (6,132 ) 232,646 GNMA 47 (29,687 ) 1,150,098 47 (49,841 ) 1,029,912 (79,528 ) 2,180,010 Private-label — — — 1 (4 ) 1,018 (4 ) 1,018 GNMA commercial mortgage-related securities 4 (2,397 ) 63,846 89 (53,427 ) 1,187,406 (55,824 ) 1,251,252 FFELP asset backed securities 6 (101 ) 67,798 — — — (101 ) 67,798 Total 75 $ (32,768 ) $ 1,342,269 152 $ (108,825 ) $ 2,391,452 $ (141,593 ) $ 3,733,721 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) 1,288 $ (22,552 ) $ 1,026,504 228 $ (10,779 ) $ 187,493 $ (33,332 ) $ 1,213,997 Residential mortgage-related securities FNMA / FHLMC 22 (1,798 ) 64,876 18 (1,469 ) 25,980 (3,266 ) 90,856 GNMA 39 (2,676 ) 89,367 46 (12,662 ) 262,952 (15,337 ) 352,319 GNMA commercial mortgage-related securities 1 (951 ) 28,308 24 (25,074 ) 470,212 (26,026 ) 498,520 Total 1,350 $ (27,976 ) $ 1,209,055 316 $ (49,983 ) $ 946,637 $ (77,961 ) $ 2,155,692 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, 2017 . Less than 12 months 12 months or more Total December 31, 2017 Number Unrealized Fair Number Unrealized Fair Unrealized Fair ($ in Thousands) Investment securities available for sale U.S. Treasury securities 1 $ (7 ) $ 996 — $ — $ — $ (7 ) $ 996 Residential mortgage-related securities FNMA / FHLMC 9 (572 ) 69,939 9 (2,062 ) 142,093 (2,634 ) 212,032 GNMA 44 (8,927 ) 1,028,221 25 (22,451 ) 737,198 (31,378 ) 1,765,419 Private-label — — — 1 (8 ) 1,059 (8 ) 1,059 GNMA commercial mortgage-related securities 33 (5,554 ) 480,514 70 (28,347 ) 1,026,642 (33,901 ) 1,507,156 FFELP asset backed securities 1 (13 ) 12,158 — — — (13 ) 12,158 Other debt securities 1 (12 ) 188 — — — (12 ) 188 Other equity securities 3 (14 ) 1,487 — — — (14 ) 1,487 Total 92 $ (15,099 ) $ 1,593,503 105 $ (52,868 ) $ 1,906,992 $ (67,967 ) $ 3,500,495 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) 157 $ (746 ) $ 122,761 132 $ (2,431 ) $ 127,043 $ (3,177 ) $ 249,804 Residential mortgage-related securities FNMA / FHLMC 8 (73 ) 13,143 10 (417 ) 16,262 (490 ) 29,405 GNMA 35 (3,373 ) 268,388 18 (3,026 ) 120,892 (6,399 ) 389,280 GNMA commercial mortgage-related securities 2 (299 ) 52,997 23 (15,457 ) 486,891 (15,756 ) 539,888 Total 202 $ (4,491 ) $ 457,289 183 $ (21,331 ) $ 751,088 $ (25,822 ) $ 1,208,377 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 September 30, 2018 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 unrealized losses at September 30, 2018 for mortgage-related securities is due to the increase in overall interest rates. The U.S. Treasury 3 year and 5 year rates increased by 90 basis points ("bp") and 74 bp, respectively, from December 31, 2017 . The Corporation does not intend to sell nor does it believe that it will be required to sell the securities in an unrealized loss position before recovery of their amortized cost basis. 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 September 30, 2018 and December 31, 2017 , the Corporation had FHLB stock of $144 million and $89 million , respectively. The Corporation had Federal Reserve Bank stock of $77 million and $76 million at September 30, 2018 and December 31, 2017

Loans

Loans	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Loans	Loans The period end loan composition was as follows. September 30, 2018 (a) December 31, ($ in Thousands) Commercial and industrial $ 7,159,941 $ 6,399,693 Commercial real estate — owner occupied 867,682 802,209 Commercial and business lending 8,027,622 7,201,902 Commercial real estate — investor 3,924,499 3,315,254 Real estate construction 1,416,209 1,451,684 Commercial real estate lending 5,340,708 4,766,938 Total commercial 13,368,330 11,968,840 Residential mortgage 8,227,649 7,546,534 Home equity 901,275 883,804 Other consumer 369,858 385,813 Total consumer 9,498,782 8,816,151 Total loans $ 22,867,112 $ 20,784,991 (a) Includes $13 million of purchased credit-impaired loans The following table presents commercial and consumer loans by credit quality indicator at September 30, 2018 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 6,886,363 $ 78,964 $ 144,468 $ 50,146 $ 7,159,941 Commercial real estate - owner occupied 823,615 6,762 32,526 4,779 867,682 Commercial and business lending 7,709,978 85,725 176,994 54,925 8,027,622 Commercial real estate - investor 3,790,423 64,509 49,842 19,725 3,924,499 Real estate construction 1,401,585 10,078 3,392 1,154 1,416,209 Commercial real estate lending 5,192,008 74,587 53,234 20,879 5,340,708 Total commercial 12,901,986 160,312 230,228 75,804 13,368,330 Residential mortgage 8,154,521 1,159 6,073 65,896 8,227,649 Home equity 887,690 1,113 148 12,324 901,275 Other consumer 369,192 598 — 68 369,858 Total consumer 9,411,403 2,870 6,221 78,288 9,498,782 Total $ 22,313,389 $ 163,182 $ 236,449 $ 154,092 $ 22,867,112 The following table presents commercial and consumer loans by credit quality indicator at December 31, 2017 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 6,015,884 $ 157,245 $ 113,778 $ 112,786 $ 6,399,693 Commercial real estate - owner occupied 723,291 14,181 41,997 22,740 802,209 Commercial and business lending 6,739,175 171,426 155,775 135,526 7,201,902 Commercial real estate - investor 3,266,389 24,845 19,291 4,729 3,315,254 Real estate construction 1,421,504 29,206 — 974 1,451,684 Commercial real estate lending 4,687,893 54,051 19,291 5,703 4,766,938 Total commercial 11,427,068 225,477 175,066 141,229 11,968,840 Residential mortgage 7,490,860 426 1,616 53,632 7,546,534 Home equity 868,958 1,137 195 13,514 883,804 Other consumer 384,990 652 — 171 385,813 Total consumer 8,744,808 2,215 1,811 67,317 8,816,151 Total $ 20,171,876 $ 227,692 $ 176,877 $ 208,546 $ 20,784,991 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 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 September 30, 2018 . Accruing Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Nonaccrual (a) Total ($ in Thousands) Commercial and industrial $ 7,103,744 $ 5,592 $ 140 $ 319 $ 50,146 $ 7,159,941 Commercial real estate - owner occupied 856,777 5,589 537 — 4,779 867,682 Commercial and business lending 7,960,521 11,181 677 319 54,925 8,027,622 Commercial real estate - investor 3,904,401 373 — — 19,725 3,924,499 Real estate construction 1,414,538 517 — — 1,154 1,416,209 Commercial real estate lending 5,318,939 890 — — 20,879 5,340,708 Total commercial 13,279,460 12,071 677 319 75,804 13,368,330 Residential mortgage 8,152,854 7,829 1,070 — 65,896 8,227,649 Home equity 880,871 6,989 1,091 — 12,324 901,275 Other consumer 365,955 1,249 730 1,856 68 369,858 Total consumer 9,399,680 16,067 2,891 1,856 78,288 9,498,782 Total $ 22,679,140 $ 28,138 $ 3,568 $ 2,175 $ 154,092 $ 22,867,112 (a) Of the total nonaccrual loans, $92 million or 60% were current with respect to payment at September 30, 2018 . The following table presents loans by past due status at December 31, 2017 . Accruing Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Nonaccrual (a) Total ($ in Thousands) Commercial and industrial $ 6,286,369 $ 170 $ 101 $ 267 $ 112,786 $ 6,399,693 Commercial real estate - owner occupied 779,421 48 — — 22,740 802,209 Commercial and business lending 7,065,790 218 101 267 135,526 7,201,902 Commercial real estate - investor 3,310,000 374 — 151 4,729 3,315,254 Real estate construction 1,450,459 168 83 — 974 1,451,684 Commercial real estate lending 4,760,459 542 83 151 5,703 4,766,938 Total commercial 11,826,249 760 184 418 141,229 11,968,840 Residential mortgage 7,483,350 9,186 366 — 53,632 7,546,534 Home equity 863,465 5,688 1,137 — 13,514 883,804 Other consumer 382,186 1,227 780 1,449 171 385,813 Total consumer 8,729,001 16,101 2,283 1,449 67,317 8,816,151 Total $ 20,555,250 $ 16,861 $ 2,467 $ 1,867 $ 208,546 $ 20,784,991 (a) Of the total nonaccrual loans, $135 million or 65% were current with respect to payment at December 31, 2017 . The following table presents impaired loans individually evaluated under ASC Topic 310, excluding $13 million of purchased credit-impaired loans, at September 30, 2018 . Recorded Unpaid Related Average Interest ($ in Thousands) Loans with a related allowance Commercial and industrial $ 57,935 $ 68,894 $ 6,013 $ 70,339 $ 1,121 Commercial real estate — owner occupied 3,746 3,752 20 15,460 143 Commercial and business lending 61,681 72,646 6,033 85,799 1,264 Commercial real estate — investor 2,069 2,148 287 14,929 13 Real estate construction 440 516 74 451 22 Commercial real estate lending 2,509 2,664 361 15,380 35 Total commercial 64,190 75,310 6,394 101,179 1,299 Residential mortgage 40,797 44,197 5,937 41,589 1,321 Home equity 9,692 10,689 3,327 9,846 431 Other consumer 1,186 1,188 123 1,188 2 Total consumer 51,675 56,074 9,387 52,623 1,754 Total loans (a) $ 115,865 $ 131,384 $ 15,781 $ 153,802 $ 3,053 Loans with no related allowance Commercial and industrial $ 28,311 $ 41,615 $ — $ 31,955 $ (348 ) Commercial real estate — owner occupied 3,772 4,823 — 4,043 — Commercial and business lending 32,083 46,438 — 35,998 (348 ) Commercial real estate — investor 9,917 14,230 — 993 892 Real estate construction — — — — — Commercial real estate lending 9,917 14,230 — 993 892 Total commercial 42,000 60,668 — 36,991 544 Residential mortgage 9,925 10,047 — 10,504 172 Home equity 778 796 — 1,277 5 Other consumer — — — — — Total consumer 10,703 10,843 — 11,781 177 Total loans (a) $ 52,703 $ 71,511 $ — $ 48,772 $ 721 Total Commercial and industrial $ 86,246 $ 110,509 $ 6,013 $ 102,294 $ 773 Commercial real estate — owner occupied 7,518 8,575 20 19,503 143 Commercial and business lending 93,764 119,084 6,033 121,797 916 Commercial real estate — investor 11,986 16,378 287 15,922 905 Real estate construction 440 516 74 451 22 Commercial real estate lending 12,426 16,894 361 16,373 927 Total commercial 106,190 135,978 6,394 138,170 1,843 Residential mortgage 50,722 54,244 5,937 52,093 1,493 Home equity 10,470 11,485 3,327 11,123 436 Other consumer 1,186 1,188 123 1,188 2 Total consumer 62,378 66,917 9,387 64,404 1,931 Total loans (a) $ 168,568 $ 202,895 $ 15,781 $ 202,574 $ 3,774 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 75% of the unpaid principal balance at September 30, 2018 . The following table presents impaired loans individually evaluated under ASC Topic 310 at December 31, 2017 . Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized ($ in Thousands) Loans with a related allowance Commercial and industrial $ 81,649 $ 83,579 $ 10,838 $ 58,494 $ 2,629 Commercial real estate — owner occupied 23,796 23,937 2,973 12,124 736 Commercial and business lending 105,445 107,516 13,811 70,618 3,365 Commercial real estate — investor 17,823 17,862 1,597 16,924 1,694 Real estate construction 467 578 86 484 29 Commercial real estate lending 18,290 18,440 1,683 17,408 1,723 Total commercial 123,735 125,956 15,494 88,026 5,088 Residential mortgage 40,561 42,922 6,512 40,411 1,614 Home equity 10,250 10,986 3,718 10,521 549 Other consumer 1,135 1,138 122 1,140 3 Total consumer 51,946 55,046 10,352 52,072 2,166 Total loans (a) $ 175,681 $ 181,002 $ 25,846 $ 140,098 $ 7,254 Loans with no related allowance Commercial and industrial $ 60,595 $ 82,839 $ — $ 89,275 $ 492 Commercial real estate — owner occupied 2,438 2,829 — 1,948 36 Commercial and business lending 63,033 85,668 — 91,223 528 Commercial real estate — investor 1,295 1,295 — — 45 Real estate construction — — — — — Commercial real estate lending 1,295 1,295 — — 45 Total commercial 64,328 86,963 — 91,223 573 Residential mortgage 6,925 7,204 — 4,999 217 Home equity 641 645 — 540 7 Other consumer — — — — — Total consumer 7,566 7,849 — 5,539 224 Total loans (a) $ 71,894 $ 94,812 $ — $ 96,762 $ 797 Total Commercial and industrial $ 142,244 $ 166,418 $ 10,838 $ 147,769 $ 3,121 Commercial real estate — owner occupied 26,234 26,766 2,973 14,072 772 Commercial and business lending 168,478 193,184 13,811 161,841 3,893 Commercial real estate — investor 19,118 19,157 1,597 16,924 1,739 Real estate construction 467 578 86 484 29 Commercial real estate lending 19,585 19,735 1,683 17,408 1,768 Total commercial 188,063 212,919 15,494 179,249 5,661 Residential mortgage 47,486 50,126 6,512 45,410 1,831 Home equity 10,891 11,631 3,718 11,061 556 Other consumer 1,135 1,138 122 1,140 3 Total consumer 59,512 62,895 10,352 57,611 2,390 Total loans (a) $ 247,575 $ 275,814 $ 25,846 $ 236,860 $ 8,051 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 80% of the unpaid principal balance at December 31, 2017 . Troubled Debt Restructurings (“Restructured Loans”) Loans are considered restructured loans if concessions have been granted to borrowers that are experiencing financial difficulty. The following table presents nonaccrual and performing restructured loans by loan portfolio. September 30, 2018 December 31, 2017 Performing Restructured Loans Nonaccrual Restructured Loans (a) Performing Restructured Loans Nonaccrual Restructured Loans (a) ($ in Thousands) Commercial and industrial $ 38,885 $ 142 $ 30,047 $ 1,776 Commercial real estate — owner occupied 3,746 — 3,989 — Commercial real estate — investor 350 9,917 14,389 — Real estate construction 218 222 310 157 Residential mortgage 16,986 20,952 17,068 18,991 Home equity 7,792 2,515 7,705 2,537 Other consumer 1,177 9 1,110 25 Total $ 69,154 $ 33,757 $ 74,618 $ 23,486 (a) Nonaccrual restructured loans have been included within nonaccrual loans. The Corporation had a recorded investment of approximately $10 million in loans modified in troubled debt restructurings during the nine months ended September 30, 2018 , of which $4 million were in accrual status and approximately $6 million were in nonaccrual pending a sustained period of repayment. The following table provides the number of loans modified in a troubled debt restructuring by loan portfolio, the recorded investment and unpaid principal balance for the nine months ended September 30, 2018 and 2017 . Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) ($ in Thousands) Commercial and industrial 6 $ 1,954 $ 1,995 19 $ 11,387 $ 15,898 Commercial real estate — owner occupied — — — 2 710 710 Commercial real estate — investor 1 958 1,022 — — — Residential mortgage 29 5,655 5,733 48 4,445 4,638 Home equity 32 1,552 1,582 35 934 1,182 Other consumer 3 19 21 — — — Total 71 $ 10,138 $ 10,353 104 $ 17,476 $ 22,428 (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 nine months ended September 30, 2018 , 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 nine months ended September 30, 2018 . The following table provides the number of loans modified in a troubled debt restructuring during the previous twelve months which subsequently defaulted during the nine months ended September 30, 2018 and 2017 and the recorded investment in these restructured loans as of September 30, 2018 and 2017 . Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment ($ in Thousands) Commercial and industrial 3 $ — 1 $ 1 Residential mortgage 12 2,579 21 1,335 Home equity 28 1,599 14 371 Total 43 $ 4,178 36 $ 1,707 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. Allowance for Credit Losses 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. The following table presents a summary of the changes in the allowance for loan losses by portfolio segment for the nine months ended September 30, 2018 . ($ in Thousands) Commercial and Commercial real estate - owner occupied Commercial real estate - Real estate Residential Home Other Total December 31, 2017 $ 123,068 $ 10,352 $ 41,059 $ 34,370 $ 29,607 $ 22,126 $ 5,298 $ 265,880 Charge offs (29,707 ) (1,361 ) (5,278 ) (298 ) (1,310 ) (2,508 ) (3,923 ) (44,385 ) Recoveries 9,609 354 139 340 1,049 2,171 593 14,255 Net Charge offs (20,098 ) (1,007 ) (5,139 ) 42 (261 ) (337 ) (3,330 ) (30,130 ) Provision for loan losses 2,643 105 5,737 (7,676 ) (1,884 ) (2,101 ) 3,676 500 September 30, 2018 $ 105,613 $ 9,451 $ 41,657 $ 26,737 $ 27,461 $ 19,687 $ 5,644 $ 236,250 Allowance for loan losses Individually evaluated for impairment $ 6,013 $ 20 $ 287 $ 74 $ 5,937 $ 3,327 $ 123 $ 15,781 Collectively evaluated for impairment 99,600 9,431 41,370 26,663 21,524 16,360 5,521 220,469 Acquired and accounted for under ASC 310-30 (a) — — — — — — — — Total allowance for loan losses $ 105,613 $ 9,451 $ 41,657 $ 26,737 $ 27,461 $ 19,687 $ 5,644 $ 236,250 Loans Individually evaluated for impairment $ 86,246 $ 7,518 $ 11,986 $ 440 $ 50,722 $ 10,470 $ 1,186 $ 168,568 Collectively evaluated for impairment 7,071,043 858,747 3,904,266 1,415,745 8,176,217 890,721 368,672 22,685,411 Acquired and accounted for under ASC 310-30 (a) 2,652 1,416 8,247 24 710 84 — 13,133 Total loans $ 7,159,941 $ 867,682 $ 3,924,499 $ 1,416,209 $ 8,227,649 $ 901,275 $ 369,858 $ 22,867,112 (a) Loans acquired in business combinations and accounted for under ASC Subtopic 310-30 "Receivables — Loans and Debt Securities Acquired with Deteriorated Credit Quality." For comparison purposes, a summary of the changes in the allowance for loan losses by portfolio segment for the year ended December 31, 2017 , was as follows. ($ in Thousands) Commercial and Commercial real estate Commercial real estate - Real estate Residential Home Other Total December 31, 2016 $ 140,126 $ 14,034 $ 45,285 $ 26,932 $ 27,046 $ 20,364 $ 4,548 $ 278,335 Charge offs (44,533 ) (344 ) (991 ) (604 ) (2,611 ) (2,724 ) (4,439 ) (56,246 ) Recoveries 11,465 173 242 74 927 3,194 716 16,791 Net Charge offs (33,068 ) (171 ) (749 ) (530 ) (1,684 ) 470 (3,723 ) (39,455 ) Provision for loan losses 16,010 (3,511 ) (3,477 ) 7,968 4,245 1,292 4,473 27,000 December 31, 2017 $ 123,068 $ 10,352 $ 41,059 $ 34,370 $ 29,607 $ 22,126 $ 5,298 $ 265,880 Allowance for loan losses Individually evaluated for impairment $ 10,838 $ 2,973 $ 1,597 $ 86 $ 6,512 $ 3,718 $ 122 $ 25,846 Collectively evaluated for impairment 112,230 7,379 39,462 34,284 23,095 18,408 5,176 240,034 Total allowance for loan losses $ 123,068 $ 10,352 $ 41,059 $ 34,370 $ 29,607 $ 22,126 $ 5,298 $ 265,880 Loans Individually evaluated for impairment $ 142,244 $ 26,234 $ 19,118 $ 467 $ 47,486 $ 10,891 $ 1,135 $ 247,575 Collectively evaluated for impairment 6,257,449 775,975 3,296,136 1,451,217 7,499,048 872,913 384,678 20,537,416 Total loans $ 6,399,693 $ 802,209 $ 3,315,254 $ 1,451,684 $ 7,546,534 $ 883,804 $ 385,813 $ 20,784,991 The allowance related to the oil and gas portfolio was $10 million at September 30, 2018 and represented 1.4% of total oil and gas loans. ($ in Millions) Nine Months Ended September 30, 2018 Year Ended December 31, 2017 Balance at beginning of period $ 27 $ 38 Charge offs (24 ) (25 ) Recoveries 3 — Net Charge offs (20 ) (25 ) Provision for loan losses 3 14 Balance at end of period $ 10 $ 27 Allowance for loan losses Individually evaluated for impairment $ — $ 5 Collectively evaluated for impairment 10 22 Total allowance for loan losses $ 10 $ 27 Loans Individually evaluated for impairment $ 32 $ 77 Collectively evaluated for impairment 700 523 Total loans $ 731 $ 600 The following table presents a summary of the changes in the allowance for unfunded commitments. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Allowance for Unfunded Commitments Balance at beginning of period $ 24,400 $ 25,400 Provision for unfunded commitments (1,500 ) (1,000 ) Amount recorded at acquisition 2,436 — Balance at end of period $ 25,336 $ 24,400 Loans Acquired in Acquisition Loans acquired in a business combination are recorded at estimated fair value on their purchase date without a carryover of the related allowance for loan and lease losses. Acquired loans are segregated into two types: • Performing loans are accounted for in accordance with ASC Topic 310-20 "Nonrefundable Fees and Other Costs" as these loans do not have evidence of credit deterioration since origination. • Nonperforming loans are accounted for in accordance with ASC Topic 310-30 as they display significant credit deterioration since origination. For performing loans the difference between the estimated fair value of the loans and the principal outstanding is accreted over the remaining life of the loans. In accordance with ASC 310-30, purchased credit-impaired loans are pooled by loan type and the difference between contractually required payments at acquisition and the cash flows expected to be collected is referred to as the non-accretable difference. Further, any excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable yield and is recognized into interest income over the remaining life of the loan pools when there is a reasonable expectation about the amount and timing of such cash flows. If a reasonable expectation on the amount or timing of such cash flows cannot be determined, accretion of the fair value discount for nonperforming loans will be recognized using the cost recovery method of accounting. Changes in the accretable yield for loans acquired and accounted for under ASC Topic 310-30 were as follows for the nine months ended September 30, 2018 and for the year ended December 31, 2017 Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Changes in Accretable Yield Balance at beginning of period $ — $ — Purchases 4,853 — Accretion (310 ) — Net reclassification from non-accretable yield 144 — Other (a) (5 ) — Balance at end of period $ 4,681 $ — (a) Primarily includes charge-offs which are accounted for under ASC Subtopic 310-30 "Receivables — Loans and Debt Securities Acquired with Deteriorated Credit Quality." For loans acquired, the fair value of purchased credit-impaired loans, on the acquisition date, was determined based on assigned risk ratings, expected cash flows and the fair value of loan collateral. The fair value of loans that were non-impaired was determined based on estimates of losses on defaults and other market factors. At September 30, 2018 , the Corporation had a total of approximately $27 million in net unaccreted purchase discount, of which approximately $21 million was related to performing loans and approximately $6 million

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Other Intangible Assets Goodwill Goodwill is not amortized but is instead 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 Corporation conducted its most recent annual impairment testing in May 2018, 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 2018 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 have been no events since the May 2018 impairment testing that have changed the Corporation's impairment assessment conclusion. There were no impairment charges recorded in 2017 or the first nine months of 2018 . At September 30, 2018 , the Corporation had goodwill of $1.2 billion , compared to $976 million at December 31, 2017. Goodwill increased $175 million related to the Bank Mutual acquisition, $10 million related to the acquisition of Diversified, and $7 million related to the acquisition of Anderson. 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. During the first quarter of 2018, the Corporation added approximately $58 million of core deposit intangibles as a result of the Bank Mutual acquisition. In addition, the Corporation added approximately $8 million of other intangibles relating to customer relationships associated with the Diversified acquisition. During the second quarter of 2018, the Corporation added approximately $3 million of other intangibles related to customer relationships associated with the Anderson acquisition. See Note 2 for additional information on the Corporation's acquisitions. For core deposit intangibles and other intangibles, changes in the gross carrying amount, accumulated amortization, and net book value were as follows. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Core deposit intangibles Gross carrying amount $ 58,100 $ 4,385 Accumulated amortization (3,873 ) (4,385 ) Net book value $ 54,227 $ — Additions during the periods $ 58,100 $ — Amortization during the year $ 3,873 $ 112 Other intangibles Gross carrying amount $ 44,931 $ 34,572 Reductions due to sale (43 ) — Accumulated amortization (21,045 ) (18,992 ) Net book value $ 23,843 $ 15,580 Additions during the period $ 10,359 $ 2,162 Amortization during the year $ 2,053 $ 1,847 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 evaluates its mortgage servicing rights asset for impairment at minimum on a quarterly basis. 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. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Mortgage servicing rights Mortgage servicing rights at beginning of period $ 59,168 $ 62,085 Additions from acquisition 8,136 — Additions 7,826 7,167 Amortization (7,143 ) (10,084 ) Mortgage servicing rights at end of period $ 67,987 $ 59,168 Valuation allowance at beginning of period (784 ) (609 ) (Additions) recoveries, net 669 (175 ) Valuation allowance at end of period (115 ) (784 ) Mortgage servicing rights, net $ 67,872 $ 58,384 Fair value of mortgage servicing rights $ 87,120 $ 64,387 Portfolio of residential mortgage loans serviced for others (“servicing portfolio”) $ 8,547,230 $ 7,646,846 Mortgage servicing rights, net to servicing portfolio 0.79 % 0.76 % Mortgage servicing rights expense (a) $ 6,474 $ 10,259 (a) 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 September 30, 2018 . 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) Three Months Ending December 31, 2018 $ 1,453 $ 780 $ 2,362 2019 5,810 2,824 9,029 2020 5,810 2,707 7,892 2021 5,810 2,682 6,873 2022 5,810 2,659 5,995 2023 5,810 2,640 5,246 Beyond 2023 23,724 9,551 30,590 Total Estimated Amortization Expense $ 54,227 $ 23,843 $ 67,987

Short and Long-Term Funding

Short and Long-Term Funding	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Short and Long-Term Funding	Short and Long-Term Funding The following table presents the components of short-term funding (funding with original contractual maturities of one year or less), long-term funding (funding with original contractual maturities greater than one year), and FHLB advances (funding based on original contractual maturities). September 30, 2018 December 31, 2017 ($ in Thousands) Short-Term Funding Federal funds purchased $ 25,890 $ 141,950 Securities sold under agreements to repurchase 140,666 182,865 Federal funds purchased and securities sold under agreements to repurchase 166,556 324,815 Commercial paper 43,604 67,467 Total short-term funding $ 210,159 $ 392,282 Long-Term Funding Senior notes, at par $ 550,000 $ 250,000 Subordinated notes, at par 250,000 250,000 Other long-term funding and capitalized costs (4,785 ) (2,718 ) Total long-term funding 795,215 497,282 Total short and long-term funding, excluding FHLB advances $ 1,005,375 $ 889,564 FHLB Advances Short-term FHLB advances $ 405,000 $ 284,000 Long-term FHLB advances 2,927,655 2,900,168 Total FHLB advances $ 3,332,655 $ 3,184,168 Total short and long-term funding $ 4,338,030 $ 4,073,732 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 September 30, 2018 , the Corporation pledged agency mortgage-related securities with a fair value of $237 million as collateral for the repurchase agreements. Securities pledged as collateral under repurchase agreements are maintained with the Corporation's safekeeping agents and are monitored on a daily basis due to the market risk of fair value changes in the underlying securities. The Corporation generally pledges excess securities to ensure there is sufficient collateral to satisfy short-term fluctuations in both the repurchase agreement balances and the fair value of the underlying securities. The remaining contractual maturity of the securities sold under agreements to repurchase in the consolidated balance sheets as of September 30, 2018 and December 31, 2017 are presented in the following table. Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 days 30-90 days Greater than 90 days Total ($ in Thousands) September 30, 2018 Repurchase agreements Agency mortgage-related securities $ 140,666 $ — $ — $ — $ 140,666 Total $ 140,666 $ — $ — $ — $ 140,666 December 31, 2017 Repurchase agreements Agency mortgage-related securities $ 182,865 $ — $ — $ — $ 182,865 Total $ 182,865 $ — $ — $ — $ 182,865 Long-Term Funding Senior Notes In August 2018, Associated Bank, N.A. issued $300 million of senior notes, due August 2021, and callable July 2021. The senior notes have a fixed coupon interest rate of 3.50% and were issued at a discount. 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. 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. FHLB Advances At September 30, 2018 , the Corporation had $3.3 billion of FHLB advances, up $ 148 million from December 31, 2017 . As of September 30, 2018 , the Corporation had $ 2.6 billion of putable FHLB advances with a one-time option where the FHLB can call the advance prior to the contractual maturity. The contractual weighted average life to the put date of these advances was 1.2 years , with put dates ranging from 2019 through 2020. The weighted average life to contractual maturity on these advances was 7.8 years , with those dates ranging from 2023 through 2028. As of September 30, 2018 , it is anticipated that all of these advances will be called by the FHLB on their put date. The original contractual maturity or next put date of the Corporation's FHLB advances as of September 30, 2018 and December 31, 2017 are presented in the following table. September 30, 2018 December 31, 2017 Amount Weighted Average Contractual Coupon Rate Amount Weighted Average Contractual Coupon Rate ($ in Thousands) Maturity or put date 1 year or less $ 1,371,059 1.76 % $ 2,434,000 1.26 % After 1 but within 2 1,662,019 2.29 % 750,013 1.23 % After 2 but within 3 216,289 2.53 % 155 4.91 % After 3 years 83,289 2.62 % — — % FHLB advances and overall rate $ 3,332,655 2.10 % $ 3,184,168 1.26 %

Derivative and Hedging Activiti

Derivative and Hedging Activities	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative and Hedging Activities	Derivative and Hedging Activities The Corporation is exposed to certain risk arising from both its business operations and economic conditions. The Corporation principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its assets and liabilities and the use of derivative financial instruments. Specifically, the Corporation enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Corporation's derivative financial instruments are used to manage differences in the amount, timing, and duration of the Corporation's known or expected cash receipts and its known or expected cash payments principally related to the Corporation's assets. 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 pledged $33 million of investment securities as collateral at September 30, 2018 , and pledged $24 million of investment securities as collateral at December 31, 2017 . 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 September 30, 2018 , the Corporation posted $37 million of cash collateral for the margin compared to $22 million at December 31, 2017 . Fair Value Hedges of Interest Rate Risk The Corporation is exposed to changes in the fair value of certain of its pools of prepayable fixed-rate assets due to changes in benchmark interest rates. The Corporation uses interest rate swaps to manage its exposure to changes in fair value on these instruments attributable to changes in the designated benchmark interest rate. Interest rate swaps designated as fair value hedges involve the payment of fixed-rate amounts to a counterparty in exchange for the Corporation receiving variable-rate payments over the life of the agreements without the exchange of the underlying notional amount. For derivatives designated and that qualify as fair value hedges, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in interest income. Derivatives to Accommodate Customer Needs The Corporation also facilitates customer borrowing activity by entering 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 markets, 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. The Corporation's 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. 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. 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. The table below identifies the balance sheet category and fair values of the Corporation’s derivative instruments. September 30, 2018 December 31, 2017 ($ in Thousands) Notional Amount Fair Balance Sheet Notional Amount Fair Balance Sheet Derivatives not designated as hedging instruments Interest rate-related instruments — customer and mirror $ 2,712,813 $ 68,916 Trading assets $ 2,183,687 $ 28,494 Trading assets Interest rate-related instruments — customer and mirror 2,712,813 (68,103 ) Trading liabilities 2,183,687 (28,035 ) Trading liabilities Foreign currency exchange forwards 124,137 1,974 Trading assets 124,851 2,495 Trading assets Foreign currency exchange forwards 119,748 (1,840 ) Trading liabilities 118,094 (2,339 ) Trading liabilities Commodity contracts 401,849 69,439 Trading assets 457,868 38,686 Trading assets Commodity contracts 401,968 (68,997 ) Trading liabilities 457,108 (37,286 ) Trading liabilities Interest rate lock commitments (mortgage) 259,762 1,685 Other assets 222,736 1,538 Other assets Forward commitments (mortgage) 271,561 1,352 Other assets 164,567 (313 ) Other liabilities Purchased options (time deposit) 21,269 577 Other assets 31,063 1,175 Other assets Written options (time deposit) 21,269 (577 ) Other liabilities 31,063 (1,175 ) Other liabilities Derivatives designated as hedging instruments Interest Rate Products 500,000 4,902 Other assets — — — The following table presents amounts that were recorded on the balance sheet related to cumulative basis adjustment for fair value hedges. Line Item in the Statement of Financial Position in Which the Hedged Item is Included Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) ($ in Thousands) September 30, 2018 Loans and investment securities receivables (a) $ 495,069 $ (4,931 ) Total $ 495,069 $ (4,931 ) (a) These amounts include the amortized cost basis of closed portfolios used to designated hedging relationships in which the hedged item is the last layer expected to be remaining at the end of the hedging relationship. At September 30, 2018, the amortized cost basis of the closed portfolios used in these hedging relationships was $1.1 billion ; the negative cumulative basis adjustments associated with these hedging relationships was $5 million; and the amounts of the designated hedged items were $500 million . The table below identifies the effect of fair value hedge accounting on the Corporation's statement of performance during the nine months ended September 30, 2018 . Location and Amount of Gain or (Loss) Recognized in Income on Fair Value and Cash Flow Hedging Relationships Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Interest Income Other Income (Expense) Interest Income Other Income (Expense) Total amounts of income and expense line items presented in the statement of financial performance in which the effects of fair value or cash flow hedges are recorded $ (30 ) $ — $ — $ — The effects of fair value and cash flow hedging: Gain or (loss) on fair value hedging relationships in Subtopic 815-20 Interest contracts Hedged items (4,931 ) — — — Derivatives designated as hedging instruments 4,902 — — — The table below identifies the effect of derivatives not designated as hedging instruments on the Corporation's statement of income during the nine months ended September 30, 2018 . Income Statement Category of Gain / (Loss) Recognized in Income For the Nine Months Ended September 30, ($ in Thousands) 2018 2017 Derivative Instruments Interest rate-related instruments — customer and mirror, net Capital markets, net $ 354 $ (115 ) Interest rate lock commitments (mortgage) Mortgage banking, net 147 2,523 Forward commitments (mortgage) Mortgage banking, net 1,665 (2,674 ) Foreign currency exchange forwards Capital markets, net (22 ) (39 ) Commodity contracts Capital markets, net (958 ) 476

Balance Sheet Offsetting

Balance Sheet Offsetting	9 Months Ended
	Sep. 30, 2018
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 the Corporation has with its commercial customers are not subject to an enforceable master netting arrangement, and therefore, are excluded from this table. Gross amounts of recognized assets Gross amounts not offset in the balance sheet ($ in Thousands) Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Derivative liability available for offset Collateral received Net amount Derivative assets: (a) September 30, 2018 $ 78,124 $ — $ 78,124 $ (26,385 ) $ (50,134 ) $ 1,605 December 31, 2017 29,503 — 29,503 (16,140 ) (13,234 ) 129 Gross amounts of recognized liabilities Gross amounts not offset in the balance sheet ($ in Thousands) Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Derivative asset available for offset Collateral pledged Net amount Derivative liabilities (b) September 30, 2018 $ 64,591 $ — $ 64,591 $ (26,385 ) $ (37,480 ) $ 726 December 31, 2017 37,164 — 37,164 (16,140 ) (20,662 ) 362 (a) Includes interest and commodity instrument assets. (b) Includes interest and commodity instrument liabilities.

Commitments, Off-Balance Sheet

Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Off-Balance Sheet Arrangements, and Legal Proceedings	Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters 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. September 30, 2018 December 31, 2017 ($ in Thousands) Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale (a)(b) $ 8,471,141 $ 8,027,187 Commercial letters of credit (a) 9,122 11,886 Standby letters of credit (c) 260,092 235,361 (a) 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 September 30, 2018 or December 31, 2017 . (b) Interest rate lock commitments to originate residential mortgage loans held for sale are considered derivative instruments and are disclosed in Note 10 . (c) The Corporation has established a liability of $3 million at September 30, 2018 and $2 million at December 31, 2017 , 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 $25 million at September 30, 2018 and $24 million at December 31, 2017 , 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 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 September 30, 2018 was $132 million , compared to $147 million at December 31, 2017 . 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 principal investment 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 loan pools that support CRA loans. The timing of future cash requirements to fund these pools is dependent upon loan demand, which can vary over time. The aggregate carrying value of these investments at September 30, 2018 was $25 million , compared to $23 million at December 31, 2017 , included in other assets on the consolidated balance sheets. Related to these investments, the Corporation had remaining commitments to fund $85 million at September 30, 2018 , and $119 million at December 31, 2017 . 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. On January 31, 2017, the District Court granted the Bank’s motion for summary judgment. The receiver has appealed the District Court’s summary judgment decision to the Eighth Circuit Court of Appeals. On January 23, 2018, the District Court approved a settlement agreement between the parties. Based on the terms of the settlement agreement, the Bank expects that the litigation will not have a material adverse impact on the Bank regardless of the outcome of the appeal to the Eighth Circuit Court of Appeals. 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. Regulatory Matters A variety of consumer products, including 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. 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 the Corporation's 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 $1 million during both the nine months ended September 30, 2018 and the year ended December 31, 2017 . The loss reimbursement and settlement claims paid for the nine months ended September 30, 2018 were zero and negligible for the year ended December 31, 2017 . Make whole requests during 2017 and the first nine months of 2018 generally arose from loans sold during the period of January 1, 2012 to December 31, 2017 . Since January 1, 2012, loans sold totaled $10.8 billion at the time of sale, and consisted primarily of loans sold to GSEs. As of September 30, 2018 , approximately $7.0 billion of these sold loans remain outstanding. The balance in the mortgage repurchase reserve at the balance sheet date reflects the estimated amount of potential loss the Corporation could incur from repurchasing a loan, as well as loss reimbursements, indemnifications, and other settlement resolutions. The following summarizes the changes in the mortgage repurchase reserve. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Balance at beginning of period $ 987 $ 900 Repurchase provision expense 254 246 Charge offs, net (125 ) (159 ) Amount recorded at acquisition 88 — Balance at end of period $ 1,204 $ 987 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 September 30, 2018 , and December 31, 2017 , there were approximately $46 million and $44 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 September 30, 2018 and December 31, 2017 , there were $60 million and $73 million

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
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. Assets and Liabilities Measured at Fair Value on a Recurring Basis 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. Residential Loans Held for Sale: Residential loans held for sale, which consist generally of current production of certain fixed-rate, first-lien residential mortgage loans, are carried at estimated fair value. Management has elected the fair value option to account for all newly originated mortgage loans held for sale, which results in the financial impact of changing market conditions being reflected currently in earnings as opposed to being dependent upon the timing of sales. Therefore, the continually adjusted values better reflect the price the Corporation expects to receive from the sale of such loans. The estimated fair value is based on what secondary markets are currently offering for portfolios with similar characteristics, which the Corporation classifies as a Level 2 fair value measurement. Derivative Financial Instruments (Interest Rate-Related Instruments): The Corporation utilizes interest rate swaps to hedge exposure to interest rate risk and variability of fair value related to changes in the underlying interest rate of the hedged item. These hedged interest rate swaps are classified as fair value hedges. See Note 10 for additional disclosure regarding the Corporation’s fair value hedges. In addition, the Corporation offers interest rate-related instruments (swaps and caps) to service its 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 measurement 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 September 30, 2018 , and December 31, 2017 , 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 its 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 instruments, and are classified in Level 2 of the fair value hierarchy. See Note 10 for additional disclosures regarding the Corporation’s commodity contracts. 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. 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 September 30, 2018 , and December 31, 2017 , 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. The table below presents the Corporation’s financial instruments measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 , aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Hierarchy September 30, 2018 December 31, 2017 ($ in Thousands) Assets Investment securities available for sale U.S. Treasury securities Level 1 $ 997 $ 996 Residential mortgage-related securities FNMA / FHLMC Level 2 316,674 464,768 GNMA Level 2 2,180,010 1,913,350 Private-label Level 2 1,018 1,059 GNMA commercial mortgage-related securities Level 2 1,250,978 1,513,277 FFELP asset backed securities Level 2 299,947 145,176 Other equity securities Level 1 1,573 1,632 Other debt securities Level 2 3,000 3,188 Total investment securities available for sale Level 1 2,570 2,628 Total investment securities available for sale Level 2 4,051,627 4,040,818 Residential loans held for sale Level 2 134,361 85,544 Commercial loans held for sale Level 2 30,452 — Interest rate-related instruments Level 2 68,916 28,494 Foreign currency exchange forwards Level 2 1,974 2,495 Interest rate products (designated as hedging instruments) Level 2 4,902 — Interest rate lock commitments to originate residential mortgage loans held for sale Level 3 1,685 1,538 Forward commitments to sell residential mortgage loans Level 3 1,352 — Commodity contracts Level 2 69,439 38,686 Purchased options (time deposit) Level 2 577 1,175 Liabilities Interest rate-related instruments Level 2 $ 68,103 $ 28,035 Foreign currency exchange forwards Level 2 1,840 2,339 Forward commitments to sell residential mortgage loans Level 3 — 313 Commodity contracts Level 2 68,997 37,286 Written options (time deposit) Level 2 577 1,175 The table below presents a rollforward of the balance sheet amounts for the nine months ended September 30, 2018 and the year ended December 31, 2017 , 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, 2016 $ 200 $ 3,114 Total net gains (losses) included in income Mortgage derivative gain (loss) — (1,889 ) Transfer out of level 3 securities (a) (200 ) — Balance December 31, 2017 $ — $ 1,225 Total net gains (losses) included in income Mortgage derivative gain (loss) — 1,816 Balance September 30, 2018 $ — $ 3,041 (a) During the first quarter of 2017, the $200,000 level 3 investment security was transferred to level 2 based upon new pricing information. For Level 3 assets and liabilities measured at fair value on a recurring basis as of September 30, 2018 , 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 fair value is determined by the change in value from each loan’s rate lock date to the expected rate lock expiration date based on the underlying loan attributes, estimated closing ratios, and investor price matrix determined to be reasonably applicable to each loan commitment. The closing ratio calculation takes into consideration historical experience and loan-level attributes, 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 Risk Management Committee. At September 30, 2018 , the closing ratio was 86% . Derivative Financial Instruments (Mortgage Derivative — Forward Commitments to Sell Mortgage Loans): Mortgage derivatives include forward commitments to deliver closed end residential mortgage loans into conforming Agency Mortgage Backed Securities (To be Announced, "TBA") or conforming Cash Forward sales. The fair value of such instruments is determined by the difference of current market prices for such traded instruments or available from forward cash delivery commitments and the original traded price for such commitments. 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. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis 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. Commercial Loans Held for Sale: Commercial loans held for sale are carried at the lower of cost or estimated fair value. The estimated fair value is based on a discounted cash flow analysis, which the Corporation classifies as a Level 2 nonrecurring fair value measurement. Other Real Estate Owned: 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. For Level 3 assets and liabilities measured at fair value on a nonrecurring basis as of September 30, 2018 , the Corporation utilized the following valuation techniques and significant unobservable inputs. 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. 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. 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 the Community, Consumer, and Business segment to reconcile the fair value estimates and the key assumptions used by the respective parties in arriving at those estimates. The Associated Mortgage Risk Management 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. See Note 8 for additional disclosure regarding the Corporation’s mortgage servicing rights. The table below presents the Corporation’s assets measured at fair value on a nonrecurring basis, aggregated by the level in the fair value hierarchy within which those measurements fall. Income Statement Category of Adjustment Recognized in Income ($ in Thousands) Fair Value Hierarchy Fair Value September 30, 2018 Assets Impaired loans (a) Level 3 $ 39,438 Provision for credit losses (b) $ (13,183 ) Other real estate owned (c) Level 2 2,688 Foreclosure / OREO expense, net (965 ) Mortgage servicing rights Level 3 87,120 Mortgage banking, net 669 December 31, 2017 Assets Impaired loans (a) Level 3 $ 92,534 Provision for credit losses (b) $ (32,159 ) Other real estate owned (c) Level 2 2,604 Foreclosure / OREO expense, net (939 ) Mortgage servicing rights Level 3 64,387 Mortgage banking, net (175 ) (a) Represents individually evaluated impaired loans, net of the related allowance for loan losses. (b) Represents provision for credit losses on individually evaluated impaired loans. (c) If the fair value of the collateral exceeds the carrying amount of the asset, no charge-off or adjustment is necessary, the asset is not considered to be carried at fair value, and is therefore not included in the table. Certain nonfinancial assets and nonfinancial liabilities measured at fair value on a nonrecurring basis include the fair value analysis 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. The Corporation's significant Level 3 measurements which employ unobservable inputs that are readily quantifiable pertain to mortgage servicing rights and impaired loans. The table below presents information about these inputs and further discussion is found above. Valuation Technique Significant Unobservable Input Weighted Average Input Applied September 30, 2018 Mortgage servicing rights Discounted cash flow Discount rate 11% Mortgage servicing rights Discounted cash flow Constant prepayment rate 8% Impaired Loans Appraisals / Discounted cash flow Collateral / Discount factor 34% Fair Value of Financial Instruments The Corporation is required to disclose estimated fair values for its financial instruments. Fair value estimates are set forth below for the Corporation’s financial instruments. September 30, 2018 December 31, 2017 Fair Value Hierarchy Level Carrying Amount Fair Value Carrying Amount Fair Value ($ in Thousands) Financial assets Cash and due from banks Level 1 $ 374,168 $ 374,168 $ 483,666 $ 483,666 Interest-bearing deposits in other financial institutions Level 1 147,848 147,848 199,702 199,702 Federal funds sold and securities purchased under agreements to resell Level 1 24,325 24,325 32,650 32,650 Investment securities held to maturity Level 2 2,661,755 2,595,017 2,282,853 2,283,574 Investment securities available for sale Level 1 2,570 2,570 2,628 2,628 Investment securities available for sale Level 2 4,051,627 4,051,627 4,040,818 4,040,818 FHLB and Federal Reserve Bank stocks Level 2 220,825 220,825 165,331 165,331 Residential loans held for sale Level 2 134,361 134,361 85,544 85,544 Commercial loans held for sale Level 2 30,452 30,452 — — Loans, net Level 3 22,630,861 22,140,169 20,519,111 20,314,984 Bank and corporate owned life insurance Level 2 661,009 661,009 591,057 591,057 Derivatives (trading and other assets) Level 2 145,808 145,808 70,850 70,850 Derivatives (trading and other assets) Level 3 3,037 3,037 1,538 1,538 Financial liabilities Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts Level 3 $ 21,542,860 $ 21,542,860 $ 20,436,893 $ 20,436,893 Brokered CDs and other time deposits (a) Level 2 3,288,752 3,288,752 2,349,069 2,349,069 Short-term funding (b) Level 2 615,159 615,159 676,282 676,282 Long-term funding Level 2 3,722,870 3,719,147 3,397,450 3,411,368 Standby letters of credit (c) Level 2 2,600 2,600 2,402 2,402 Derivatives (trading and other liabilities) Level 2 139,517 139,517 68,835 68,835 Derivatives (trading and other liabilities) Level 3 — — 313 313 (a) When the estimated fair value is less than the carrying value, the carrying value is reported as the fair value. (b) The carrying amount is a reasonable estimate of fair value for existing short-term funding. (c) The commitment on standby letters of credit was $260 million and $235 million at September 30, 2018 and December 31, 2017

Retirement Plans

Retirement Plans	9 Months Ended
	Sep. 30, 2018
Defined Benefit Plan [Abstract]
Retirement Plans	Retirement Plans The Corporation has a noncontributory defined benefit retirement plan (the Retirement Account Plan (“RAP”)) covering substantially all employees who meet participation requirements. 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 legacy healthcare access to a limited group of retired employees from a previous acquisition in the Postretirement Plan. There are no other active retiree healthcare plans. Bank Mutual was acquired on February 1, 2018. The Bank Mutual Pension Plan has not yet been merged into the Corporation's Retirement Account Plan. However, Bank Mutual's Postretirement Plan was merged into the Corporation's Postretirement Plan during the first quarter of 2018. The components of net periodic benefit cost for the RAP, Bank Mutual Pension Plan, and Postretirement Plan for three and nine months ended September 30, 2018 and 2017 were as follows. Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Components of Net Periodic Benefit Cost RAP Service cost $ 1,885 $ 1,713 $ 5,670 $ 5,276 Interest cost 1,682 1,795 5,002 5,307 Expected return on plan assets (4,777 ) (4,929 ) (14,287 ) (14,692 ) Amortization of prior service cost (18 ) (19 ) (56 ) (56 ) Amortization of actuarial loss 549 619 1,474 1,594 Total net pension cost $ (680 ) $ (821 ) $ (2,197 ) $ (2,571 ) Bank Mutual Pension Plan (a) Interest cost $ 654 N/A $ 1,737 N/A Expected return on plan assets (1,220 ) N/A (2,812 ) N/A Total net pension cost $ (566 ) N/A $ (1,075 ) N/A Postretirement Plan (b) Interest cost $ 27 $ 26 $ 80 $ 74 Amortization of prior service cost (19 ) (19 ) (56 ) (57 ) Amortization of actuarial loss 2 2 6 2 Total net periodic benefit cost $ 11 $ 9 $ 30 $ 19 (a) The reported figures only include eight months of expense due to the timing of the Bank Mutual acquisition. See Note 2 for additional information on the Bank Mutual acquisition. (b) The portion of the Postretirement Plan attributed to Bank Mutual's Postretirement Plan only includes eight months of expense due to the timing of the Bank Mutual acquisition. See Note 2 for additional information on the Bank Mutual acquisition. The components of net periodic benefit cost, other than the service cost component, are included in the line item "other" of noninterest expense in the Consolidated Statements of Income. The Corporation’s funding policy is to pay at least the minimum amount required by federal law and regulations, with consideration given to the maximum funding amounts allowed. The Corporation regularly reviews the funding of its pension plans. The Corporation made a $6 million contribution to the Bank Mutual Pension Plan and a $4 million contribution to the RAP during the third quarter of 2018, as well as a $31 million

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2018
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 2017 Annual Report on Form 10-K, with certain exceptions. The more significant of these exceptions are described herein. The reportable segment results are presented based on the Corporation's internal management accounting process. 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. Additionally, the information presented is not indicative of how the segments would perform if they operated as independent entities. To determine financial performance of each segment, the Corporation allocates funds transfer pricing ("FTP") assignments, the provision for credit losses, certain noninterest expenses, income tax, and equity to each segment. Allocation methodologies are subject to periodic adjustment as the internal management accounting system is revised and business or product lines within the segments change. Also, because the development and application of these methodologies is a dynamic process, the financial results presented may be periodically reviewed. The Corporation allocates net interest income using an internal 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 offset in the Risk Management and Shared Services segment to ensure consolidated totals reflect the Corporation's net interest income. The net FTP allocation is reflected as net intersegment income (expense) in the accompanying tables. 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 2017 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). 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 2017 Annual Report on Form 10-K. 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). In addition, the Risk Management and Shared Services segment includes certain unallocated expenses related to Bank Mutual's shared services and operations prior to system conversion in late June 2018. All acquisition related costs are included in the Risk Management and Shared Services segment. Corporate and Commercial Specialty Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 113,298 $ 93,114 $ 339,718 $ 270,256 Net intersegment interest income (expense) (13,018 ) (758 ) (36,151 ) 1,359 Segment net interest income 100,280 92,356 303,567 271,615 Noninterest income 12,280 12,278 39,156 36,768 Total revenue 112,560 104,634 342,723 308,383 Credit provision (a) 11,232 9,499 32,955 32,549 Noninterest expense 41,828 39,681 122,853 116,578 Income (loss) before income taxes 59,500 55,454 186,914 159,256 Income tax expense (benefit) 12,098 19,070 36,978 53,082 Net income $ 47,402 $ 36,384 $ 149,937 $ 106,174 Return on average allocated capital (ROCET1) (b) 15.5 % 12.8 % 16.6 % 12.7 % Average earning assets $ 11,981,760 $ 10,923,762 $ 11,814,674 $ 10,846,418 Average loans 11,974,090 10,916,829 11,804,458 10,837,933 Average deposits 8,695,170 7,398,970 8,127,134 6,759,105 Average allocated capital (CET1) (b) 1,215,331 1,125,181 1,207,925 1,121,800 Allocated goodwill 524,525 428,000 Community, Consumer, and Business Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 91,323 $ 81,058 $ 268,137 $ 236,407 Net intersegment interest income (expense) 21,951 9,894 63,301 33,603 Segment net interest income 113,275 90,952 331,438 270,011 Noninterest income 73,838 67,867 224,109 198,546 Total revenue 187,113 158,819 555,547 468,557 Credit provision (a) 5,280 5,046 15,125 15,317 Noninterest expense 139,653 120,241 405,338 361,580 Income (loss) before income taxes 42,180 33,532 135,084 91,660 Income tax expense (benefit) 8,861 11,736 28,371 32,081 Net income $ 33,319 $ 21,796 $ 106,713 $ 59,579 Return on average allocated capital (ROCET1) (b) 20.0 % 14.7 % 21.9 % 13.6 % Average earning assets $ 10,456,159 $ 9,608,242 $ 10,333,412 $ 9,418,173 Average loans 10,453,485 9,602,098 10,329,888 9,414,880 Average deposits 13,716,862 11,788,606 13,518,903 11,568,220 Average allocated capital (CET1) (b) 662,017 588,841 652,745 584,774 Allocated goodwill 644,397 544,006 Risk Management and Shared Services Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 14,770 $ 15,951 $ 47,770 $ 47,552 Net intersegment interest income (expense) (8,933 ) (9,136 ) (27,150 ) (34,963 ) Segment net interest income 5,837 6,814 20,620 12,589 Noninterest income 2,183 5,750 8,257 12,822 Total revenue 8,019 12,564 28,876 25,411 Credit provision (a) (21,512 ) (9,545 ) (49,081 ) (21,866 ) Noninterest expense (c) 22,932 17,505 100,445 49,276 Income (loss) before income taxes 6,599 4,604 (22,488 ) (1,999 ) Income tax expense (benefit) 1,390 (2,217 ) (10,416 ) (15,500 ) Net income $ 5,209 $ 6,821 $ (12,072 ) $ 13,501 Return on average allocated capital (ROCET1) (b) 1.8 % 4.4 % (4.2 )% 2.2 % Average earning assets $ 8,036,951 $ 6,927,791 $ 7,912,853 $ 6,587,401 Average loans 546,142 380,210 554,824 248,165 Average deposits 2,283,886 3,253,869 2,355,566 3,486,354 Average allocated capital (CET1) (b) 635,924 405,653 603,684 387,388 Consolidated Total Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 219,392 $ 190,122 $ 655,625 $ 554,215 Net intersegment interest income (expense) — — — — Segment net interest income 219,392 190,122 655,625 554,215 Noninterest income 88,300 85,895 271,522 248,136 Total revenue 307,692 276,017 927,146 802,351 Credit provision (a) (5,000 ) 5,000 (1,000 ) 26,000 Noninterest expense 204,413 177,427 628,636 527,434 Income (loss) before income taxes 108,279 93,590 299,510 248,917 Income tax expense (benefit) 22,349 28,589 54,932 69,663 Net income $ 85,929 $ 65,001 $ 244,578 $ 179,254 Return on average allocated capital (ROCET1) (b) 13.2 % 11.7 % 12.9 % 11.0 % Average earning assets $ 30,474,870 $ 27,459,795 $ 30,060,938 $ 26,851,992 Average loans 22,973,717 20,899,137 22,689,170 20,500,978 Average deposits 24,695,918 22,441,445 24,001,604 21,813,679 Average allocated capital (CET1) (b) 2,513,272 2,119,675 2,464,354 2,093,962 Allocated goodwill 1,168,922 972,006 (a) The consolidated credit provision is equal to the actual reported provision for credit losses. (b) The Federal Reserve establishes capital adequacy requirements for the Corporation, including common equity Tier 1. For segment reporting purposes, the return on common equity Tier 1 ("ROCET1") reflects return on average allocated common equity Tier 1. 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. (c) For the three months ended September 30, 2018, the Risk Management and Shared Services segment includes approximately $2 million of acquisition related noninterest expense. For the nine months ended September 30, 2018, the Risk Management and Shared Services segment includes approximately $30 million

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following tables summarize the components of accumulated other comprehensive income (loss) at September 30, 2018 and 2017 respectively, including changes during the preceding nine and three month periods as well as any reclassifications out of accumulated other comprehensive income (loss). ($ in Thousands) Investment Securities Available For Sale Defined Benefit Pension and Post Retirement Obligations Accumulated Other Comprehensive Income (Loss) Balance January 1, 2018 $ (38,453 ) $ (24,305 ) $ (62,758 ) Other comprehensive income (loss) before reclassifications (82,099 ) — (82,099 ) Amounts reclassified from accumulated other comprehensive income (loss) Investment securities losses (gains), net 1,985 — 1,985 Personnel expense — (112 ) (112 ) Other expense — 1,480 1,480 Adjustment for adoption of ASU 2016-01 (84 ) — (84 ) Adjustment for adoption of ASU 2018-02 (8,419 ) (5,235 ) (13,654 ) Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) (684 ) — (684 ) Income tax (expense) benefit 20,796 (390 ) 20,406 Net other comprehensive income (loss) during period (68,505 ) (4,257 ) (72,762 ) Balance September 30, 2018 $ (106,958 ) $ (28,562 ) $ (135,520 ) Balance January 1, 2017 $ (20,079 ) $ (34,600 ) $ (54,679 ) Other comprehensive income (loss) before reclassifications 1,646 — 1,646 Amounts reclassified from accumulated other comprehensive income (loss) Personnel expense — (113 ) (113 ) Other expense — 1,596 1,596 Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) (2,499 ) — (2,499 ) Income tax (expense) benefit 328 (567 ) (239 ) Net other comprehensive income (loss) during period (525 ) 916 391 Balance September 30, 2017 $ (20,604 ) $ (33,684 ) $ (54,288 ) ($ in Thousands) Investments Defined Benefit Accumulated Balance July 1, 2018 $ (90,986 ) $ (28,902 ) $ (119,888 ) Other comprehensive income (loss) before reclassifications (21,345 ) — (21,345 ) Amounts reclassified from accumulated other comprehensive income (loss) Investment securities losses (gains), net (30 ) — (30 ) Personnel expense — (37 ) (37 ) Other expense — 551 551 Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) (52 ) — (52 ) Income tax (expense) benefit 5,456 (174 ) 5,282 Net other comprehensive income (loss) during period (15,971 ) 340 (15,631 ) September 30, 2018 $ (106,958 ) $ (28,562 ) $ (135,520 ) Balance July 1, 2017 $ (19,428 ) $ (34,042 ) $ (53,470 ) Other comprehensive income (loss) before reclassifications (1,986 ) — (1,986 ) Amounts reclassified from accumulated other comprehensive income (loss) Personnel expense — (38 ) (38 ) Other expense — 621 621 Interest income (Amortization of net unrealized losses (gains)on available for sale securities transferred to held to maturity securities) 76 — 76 Income tax (expense) benefit 734 (225 ) 509 Net other comprehensive income (loss) during period (1,176 ) 358 (818 ) September 30, 2017 $ (20,604 ) $ (33,684 ) $ (54,288 )

Revenues

Revenues	9 Months Ended
	Sep. 30, 2018
Revenue Recognition [Abstract]
Revenues	Revenues On January 1, 2018, the Corporation adopted Topic 606 using the modified retrospective method. As stated in Note 3 , the implementation of the new standard had an immaterial impact to the Corporation. Results for reporting periods beginning after January 1, 2018 are presented under Topic 606. Revenue is recognized when obligations under the terms of a contract with the Corporation's customer are satisfied. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or providing services. We do not have any material significant payment terms as payment is received at or shortly after the satisfaction of the performance obligation. The following table disaggregates the Corporation's revenue by major source for the three and nine months ended September 30, 2018 and 2017 . Nine Months Ended September 30, 2018 ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Insurance commissions and fees $ — $ 68,244 $ 36 $ 68,279 Service charges and deposit account fees 11,680 37,984 50 49,714 Card-based and loan fees (a) 1,023 29,512 52 30,587 Trust and asset management fees — 40,946 — 40,946 Brokerage commissions and fees — 21,001 252 21,253 Other revenue (78 ) 7,349 221 7,491 Noninterest Income (in-scope of Topic 606) 12,625 205,036 611 218,270 Noninterest Income (out-of-scope of Topic 606) 26,531 19,073 7,646 53,252 Total Noninterest Income $ 39,156 $ 224,109 $ 8,257 $ 271,522 (a) Loan fees are out-of-scope of Topic 606. Nine Months Ended September 30, 2017 ($ in Thousands) Corporate and Community, Risk Management Consolidated Insurance commissions and fees $ — $ 62,286 $ 2 $ 62,288 Service charges and deposit account fees 12,334 36,259 61 48,654 Card-based and loan fees (a) 876 25,807 17 26,700 Trust and asset management fees — 37,066 — 37,066 Brokerage commissions and fees — 13,071 — 13,071 Other revenue 591 6,626 153 7,370 Noninterest Income (in-scope of Topic 606) 13,801 181,115 233 195,149 Noninterest Income (out-of-scope of Topic 606) 22,967 17,431 12,589 52,987 Total Noninterest Income $ 36,768 $ 198,546 $ 12,822 $ 248,136 (a) Loan fees are out-of-scope of Topic 606. Three Months Ended September 30, 2018 ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Insurance commissions and fees $ — $ 21,632 $ 4 $ 21,636 Service charges and deposit account fees 3,669 13,210 25 16,904 Card-based and loan fees (a) 349 9,821 (15 ) 10,155 Trust and asset management fees — 14,140 — 14,140 Brokerage commissions and fees — 7,114 (30 ) 7,084 Other revenue 92 2,586 122 2,800 Noninterest Income (in-scope of Topic 606) 4,110 68,503 106 72,719 Noninterest Income (out-of-scope of Topic 606) 8,170 5,335 2,077 15,581 Total Noninterest Income $ 12,280 $ 73,838 $ 2,183 $ 88,300 (a) Loan fees are out-of-scope of Topic 606. Three Months Ended September 30, 2017 ($ in Thousands) Corporate and Community, Risk Management Consolidated Insurance commissions and fees $ — $ 19,813 $ 2 $ 19,815 Service charges and deposit account fees 3,824 12,432 12 16,268 Card-based and loan fees (a) 284 8,834 6 9,124 Trust and asset management fees — 12,784 — 12,785 Brokerage commissions and fees — 4,392 — 4,392 Other revenue 509 2,311 48 2,868 Noninterest Income (in-scope of Topic 606) 4,617 60,566 68 65,251 Noninterest Income (out-of-scope of Topic 606) 7,661 7,301 5,682 20,644 Total Noninterest Income $ 12,278 $ 67,867 $ 5,750 $ 85,895 (a) Loan fees are out-of-scope of Topic 606. During the first quarter of 2018, the Corporation acquired Bank Mutual. This acquisition resulted in increased service charges and deposit account fees and card-based and loan fees. In addition, the Corporation acquired Whitnell & Co., Diversified, and Anderson since the third quarter of 2017 which resulted in increased insurance commissions and fees, trust and asset management fees, and brokerage commissions. Below is a listing of performance obligations for the Corporation's main revenue streams. Revenue Stream Noninterest income in-scope of Topic 606 Insurance commissions and fees The Corporation's insurance revenue has two distinct performance obligations. The first performance obligation is the selling of the policy as an agent for the carrier. This performance obligation is satisfied upon binding of the policy. The second performance obligation is the ongoing servicing of the policy which is satisfied over the life of the policy. For employee benefits, the payment is typically received monthly. For property and casualty, payments can vary, but are typically received at, or in advance, of the policy period. Service charges and deposit account fees Service charges on deposit accounts consist of monthly service fees (i.e. business analysis fees and consumer service charges) and other deposit account related fees. The Corporation's performance obligation for monthly service fees is generally satisfied, and the related revenue recognized, over the period in which the service is provided. Other deposit account related fees are largely transactional based, and therefore, the Corporation's performance obligation is satisfied, and related revenue recognized, at a point in time. Payment for service charges on deposit accounts is primarily received immediately or in the following month through a direct charge to customers’ accounts. Card-based and loan fees (a) Card-based and loan fees are primarily comprised of debit and credit card income, ATM fees, and merchant services income. Debit and credit card income is primarily comprised of interchange fees earned whenever the Corporation's debit and credit cards are processed through card payment networks. ATM and merchant fees are largely transactional based, and therefore, the Corporation's performance obligation is satisfied, and related revenue recognized, at a point in time. Payment is typically received immediately or in the following month. Trust and asset management fees Trust and asset management income is primarily comprised of fees earned from the management and administration of trusts and other customer assets. The Corporation's performance obligation is generally satisfied over time and the resulting fees are recognized monthly, based upon the month-end market value of the assets under management and the applicable fee rate. Payment is generally received a few days after month end through a direct charge to customers’ accounts. The Corporation's performance obligation for these transactional-based services is generally satisfied, and related revenue recognized, at a point in time (i.e., as incurred). Payment is received shortly after services are rendered. Brokerage commissions and fees Brokerage commissions and fees primarily consists of investment advisory, brokerage, retirement services, and annuities. The Corporation's performance obligation for investment advisory services and retirement services is generally satisfied, and the related revenue recognized, over the period in which the services are provided. The performance obligation for annuities is satisfied upon sale of the annuity, and therefore, the related revenue is primarily recognized at the time of sale. Payment for these services are typically received immediately or in advance of the service. (a) Loan fees are out-of-scope of Topic 606. Arrangements with Multiple Performance Obligations The Corporation's contracts with customers may include multiple performance obligations. For such arrangements, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the expected cost plus margin. Practical Expedients We do not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Business combination	Business combinations The Corporation accounts for its acquisitions using the purchase accounting method. Purchase accounting requires the total purchase price to be allocated to the estimated fair values of assets acquired and liabilities assumed, including certain intangible assets that must be recognized. Typically, this allocation results in the purchase price exceeding the fair value of net assets acquired, which is recorded as goodwill. Core deposit intangibles are a measure of the value of checking, money market and savings deposits acquired in business combinations accounted for under the purchase method. Core deposit intangibles and other identified intangibles with finite useful lives are amortized using the straight line method over their estimated useful lives of up to ten years. Loans that the Corporation acquires in connection with acquisitions are recorded at fair value with no carryover of the related allowance for credit losses. Fair value of the loans involves estimating the amount and timing of principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loan when there is a reasonable expectation about the amount and timing of such cash flows. If a reasonable expectation on the amount or timing of such cash flows can't be determined, accretion of the fair value discount for nonperforming loans will be recognized using the cost recovery method of accounting. The difference between contractually required payments at acquisition and the cash flows expected to be collected at acquisition is referred to as the non-accretable discount. The non-accretable discount includes estimated future credit losses expected to be incurred over the life of the loan. Subsequent decreases to the expected cash flows will require the Corporation to evaluate the need for an additional allowance for credit losses. Subsequent improvement in expected cash flows will result in the reversal of a corresponding amount of the non-accretable discount which the Corporation will then reclassify as accretable discount that will be recognized into interest income over the remaining life of the loan.
Revenue Recognition, Policy	Revenue Recognition The Corporation recognizes revenue in accordance with ASC 606, "Revenue from Contracts with Customers." ASC 606 requires the Corporation to follow a five step process: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation. Revenue recognition under ASC 606 depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the goods or services.
New Accounting Pronouncements, Policy	New Accounting Pronouncements Adopted Standard Description Date of adoption Effect on financial statements ASU 2018-02 Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income The FASB issued an amendment to allow a reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendments in this update are effective for all entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption of the update was permitted and should be applied in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate related to the Tax Cuts and Jobs Act of 2017 is recognized. 1st Quarter 2018 The Corporation has elected to early adopt this amendment. During the first quarter of 2018, the Corporation reclassified approximately $14 million from accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act. No material impact on results of operations, financial position, or liquidity. See Consolidated Statements of Comprehensive Income and the Statement of Changes in Stockholders' Equity. ASU 2017-12 Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities The FASB issued an amendment to better align a company’s financial reporting for hedging activities with the economic objectives of those activities for both financial (e.g., interest rate) and commodity risks. The provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes. It also contains targeted improvements to simplify the application of hedge accounting guidance. This amendment is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Entities should apply the amendment on a modified retrospective transition method in which the cumulative effect of the change will be recognized within equity in the consolidated balance sheet as of the date of adoption. Early adoption was permitted, including in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes the interim period. 1st Quarter 2018 The Corporation has elected to early adopt this amendment. No material impact on results of operations, financial position, or liquidity. See Note 10 for expanded disclosures. ASU 2017-07 Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost The FASB issued an amendment to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost, including a requirement that employers disaggregate the service cost component from the other components of net benefit cost. In addition, the amendments provide explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allow only the service cost component of net benefit cost to be eligible for capitalization. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented and prospectively only for the capitalization component. Early adoption is permitted, but should be within the first interim period if interim financial statements are issued. 1st Quarter 2018 No impact on results of operations, financial position, or liquidity. The update required retrospective restatement. For the full year 2017, the Corporation reclassified approximately $9 million from personnel expense to other noninterest expense for the non-service cost components of net periodic pension cost and net periodic postretirement benefit cost. See Note 14 for expanded disclosure. ASU 2017-01 Business Combinations (Topic 805): Clarifying the Definition of a Business The FASB issued amendments to clarify the definition of a business in order to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets versus businesses. The new standard narrows the definition of a business by adding three principal clarifications if: (1) substantially all the fair value of the gross assets in the asset group is concentrated in either a single identifiable asset or group of similar identifiable assets the transaction does not involve a business, (2) the asset group does not include a minimum of an input and a substantive process, it does not represent a business, and (3) the integrated set of activities (including its inputs and processes) does not create, or have the ability to create, goods or services to customers, investment income (e,g. dividends or interest) or other revenues, then it is not a business. The overall intention is to provide consistency in applying the guidance, reduce the costs of application, and make the definition of a business more operable. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment prospectively on or after the effective date. 1st Quarter 2018 No material impact on results of operations, financial position, or liquidity. ASU 2016-18 Statement of Cash Flows (Topic 230): Restricted Cash The FASB issued an amendment to improve GAAP by providing guidance on the presentation of restricted cash or restricted cash equivalents in the statement of cash flows, in order to reduce diversity in practice. The amendment requires that a statement of cash flow explain the change during the period in the total cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included in cash and cash equivalents when reconciling the beginning and end of period total amounts shown on the statement of cash flow. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented. Early adoption is permitted, including in an interim period. 1st Quarter 2018 No impact on results of operations, financial position, or liquidity. See Consolidated Statements of Cash Flows. Standard Description Date of adoption Effect on financial statements ASU 2016-16 Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory The FASB issued an amendment requiring an entity to recognize income tax consequences on an intra-entity transfer of an asset other than inventory at the time the transaction occurs. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment by means of a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. Early adoption is permitted for all entities in the first interim period if an entity issues interim financial statements. 1st Quarter 2018 No material impact on results of operations, financial position, or liquidity. ASU 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments The FASB issued an amendment to provide clarification on where to classify cash flows involving certain cash receipts and cash payments. Under the new guidance, cash payments for debt prepayment or debt extinguishment costs should be classified as cash outflows from financing activities. The new guidance also details the specific classification of contingent consideration cash payments made after a business combination depending on the timing of payments. Lastly, cash proceeds received from corporate owned life insurance policies (including bank owned life insurance) should be classified as cash inflows from investing, while the cash payments for the premiums may be classified as cash outflows from investing, operating, or a combination of both. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented. Early adoption is permitted, including in an interim period; however, all of the amendments must be adopted in the same period. 1st Quarter 2018 No material impact on results of operations, financial position, or liquidity. ASU 2016-01 Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The FASB issued an amendment to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. This amendment supersedes the guidance to classify equity securities with readily determinable fair values into different categories, requires equity securities to be measured at fair value with changes in the fair value recognized through net income, and simplifies the impairment assessment of equity investments without readily determinable fair values. The amendment requires public business entities that are required to disclose the fair value of financial instruments measured at amortized cost on the balance sheet to measure that fair value using the exit price notion. The amendment requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option. The amendment requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or in the accompanying notes to the financial statements. The amendment reduces diversity in current practice by clarifying that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity’s other deferred tax assets. This amendment was effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities are required to apply the amendment by means of a cumulative-effect adjustment as of the beginning of the fiscal year of adoption, with the exception of the amendment related to equity securities without readily determinable fair values, which should be applied prospectively to equity investments that exist as of the date of adoption. 1st Quarter 2018 The Corporation has adopted this amendment using the cumulative-effect adjustment as of the beginning of the fiscal year of adoption. No material impact on the result of operations, financial position or liquidity. In 2008, the Corporation received Visa Class B restricted shares as part of Visa’s initial public offering. Based on the existing transfer restriction and the uncertainty of the covered litigation, the approximately 119 thousand Class B shares remaining that the Corporation owned as of September 30, 2018 are carried at a zero cost basis. See Consolidated Statements of Comprehensive Income and Note 13 Fair Value Measurements. ASU 2014-09 Revenue from Contracts with Customers (Topic 606) The FASB issued an amendment to clarify the principles for recognizing revenue and to develop a common revenue standard. The standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that “an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.” In applying the revenue model to contracts within its scope, an entity should apply the following steps: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation. The standard applies to all contracts with customers except those that are within the scope of other topics in the FASB Codification. The standard also requires significantly expanded disclosures about revenue recognition. The amendment was originally to be effective for annual reporting periods beginning after December 15, 2016 (including interim reporting periods within those periods); however, in July 2015, the FASB approved a one year deferral of the effective date to December 31, 2017. 1st Quarter 2018 The Corporation chose to adopt this amendment using the modified retrospective approach with no material impact on the Corporation's results of operations, financial position, or liquidity. See Note 17 for expanded disclosure requirements.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Estimated Fair Values of Assets Acquired and Liabilities Assumed	The following table presents the estimated fair values of the assets acquired and liabilities assumed as of the acquisition date related to Bank Mutual. Purchase Accounting Adjustments February 1, 2018 ($ in Thousands) Assets Cash and cash equivalents $ — $ 78,052 Investment securities (6,238 ) 452,867 Federal Home Loan Bank stock, at cost — 20,026 Loans (48,043 ) 1,875,877 Premises and equipment, net 2,930 42,689 Bank owned life insurance (24 ) 65,390 Goodwill 175,499 Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet) 58,100 58,100 Other real estate owned (included in other assets on the face of the Consolidated Balance Sheet) 199 4,848 Others assets $ 7,054 $ 47,158 Total assets $ 2,820,506 Liabilities Deposits $ 2,498 $ 1,840,950 Other borrowings 1,875 431,886 Other liabilities $ 4,487 $ 65,982 Total liabilities $ 2,338,818 Total consideration paid $ 481,688

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2018
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 September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 (In Thousands, except per share data) Net income $ 85,929 $ 65,001 $ 244,578 $ 179,254 Preferred stock dividends (2,409 ) (2,339 ) (7,077 ) (7,008 ) Net income available to common equity $ 83,521 $ 62,662 $ 237,501 $ 172,246 Common shareholder dividends (25,486 ) (18,149 ) (77,035 ) (54,726 ) Unvested share-based payment awards (128 ) (105 ) (396 ) (332 ) Undistributed earnings $ 57,907 $ 44,408 $ 160,070 $ 117,188 Undistributed earnings allocated to common shareholders 57,620 44,150 159,297 116,418 Undistributed earnings allocated to unvested share-based payment awards 288 258 772 770 Undistributed earnings $ 57,907 $ 44,408 $ 160,070 $ 117,188 Basic Distributed earnings to common shareholders $ 25,486 $ 18,149 $ 77,035 $ 54,726 Undistributed earnings allocated to common shareholders 57,620 44,150 159,297 116,418 Total common shareholders earnings, basic $ 83,106 $ 62,299 $ 236,332 $ 171,144 Diluted Distributed earnings to common shareholders $ 25,486 $ 18,149 $ 77,035 $ 54,726 Undistributed earnings allocated to common shareholders 57,620 44,150 159,297 116,418 Total common shareholders earnings, diluted $ 83,106 $ 62,299 $ 236,332 $ 171,144 Weighted average common shares outstanding 170,516 150,565 168,249 150,983 Effect of dilutive common stock awards 2,188 1,815 2,101 2,081 Effect of dilutive common stock warrants 98 588 526 718 Diluted weighted average common shares outstanding 172,802 152,968 170,876 153,782 Basic earnings per common share $ 0.49 $ 0.41 $ 1.40 $ 1.13 Diluted earnings per common share $ 0.48 $ 0.41 $ 1.38 $ 1.11

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Fair value assumptions of stock options	The following assumptions were used in estimating the fair value for options granted in the first nine months of 2018 and full year 2017 . 2018 2017 Dividend yield 2.50 % 2.00 % Risk-free interest rate 2.60 % 2.00 % Weighted average expected volatility 22.00 % 25.00 % Weighted average expected life 5.75 years 5.5 years Weighted average per share fair value of options $4.47 $5.30
Summary of Company's Stock Option Activities	A summary of the Corporation’s stock option activity for the nine months ended September 30, 2018 is presented below. Stock Options Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (a) Outstanding at December 31, 2017 5,118,687 $ 18.02 6.48 $ 38,028 Granted 938,740 24.50 Assumed from Bank Mutual acquisition 370,051 14.35 Exercised (966,213 ) 16.57 Forfeited or expired (63,313 ) 25.17 Outstanding at September 30, 2018 5,397,952 $ 19.07 6.48 $ 37,423 Options Exercisable at September 30, 2018 3,253,556 $ 16.89 5.24 $ 29,649
Summary of Restricted Stock Awards Activity (Excluding Salary Shares)	The following table summarizes information about the Corporation’s restricted stock activity for the nine months ended September 30, 2018 . Restricted Stock Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2017 2,026,071 $ 19.68 Granted 592,371 24.72 Vested (568,441 ) 18.33 Forfeited (50,478 ) 22.25 Outstanding at September 30, 2018 1,999,523 $ 21.94

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Gain (loss) on securities	The amortized cost and fair values of securities available for sale and held to maturity were as follows. September 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,001 $ — $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 320,148 2,658 (6,132 ) 316,674 GNMA 2,259,538 — (79,528 ) 2,180,010 Private-label 1,022 — (4 ) 1,018 GNMA commercial mortgage-related securities 1,306,802 — (55,824 ) 1,250,978 FFELP asset backed securities 298,282 1,766 (101 ) 299,947 Other debt securities 3,000 — — 3,000 Other equity securities 1,573 — — 1,573 Total investment securities available for sale $ 4,191,366 $ 4,424 $ (141,593 ) $ 4,054,197 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,682,162 $ 1,216 $ (33,332 ) $ 1,650,046 Residential mortgage-related securities FNMA / FHLMC 95,603 162 (3,266 ) 92,499 GNMA 367,536 1,753 (15,337 ) 353,952 GNMA commercial mortgage-related securities 516,454 8,092 (26,026 ) 498,520 Total investment securities held to maturity $ 2,661,755 $ 11,223 $ (77,961 ) $ 2,595,017 September 30, 2018 and 2017 are shown below. Nine Months Ended September 30, 2018 2017 ($ in Thousands) Gross gains on available for sale securities $ 1,954 $ — Gross gains on held to maturity securities — 364 Total gains 1,954 364 Gross losses on available for sale securities (3,938 ) — Gross losses on held to maturity securities $ — $ (5 ) Total losses $ (3,938 ) $ (5 ) Investment securities gains (losses), net $ (1,985 ) $ 359 Proceeds from sales of investment securities $ 601,130 $ 16,059
Investment securities available for sale	A portion of the portfolio is also comprised of asset-backed securities backed by student loans made under the Federal Family Education Loan Program ("FFELP"). The amortized cost and fair values of securities available for sale and held to maturity were as follows. September 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,001 $ — $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 320,148 2,658 (6,132 ) 316,674 GNMA 2,259,538 — (79,528 ) 2,180,010 Private-label 1,022 — (4 ) 1,018 GNMA commercial mortgage-related securities 1,306,802 — (55,824 ) 1,250,978 FFELP asset backed securities 298,282 1,766 (101 ) 299,947 Other debt securities 3,000 — — 3,000 Other equity securities 1,573 — — 1,573 Total investment securities available for sale $ 4,191,366 $ 4,424 $ (141,593 ) $ 4,054,197 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,682,162 $ 1,216 $ (33,332 ) $ 1,650,046 Residential mortgage-related securities FNMA / FHLMC 95,603 162 (3,266 ) 92,499 GNMA 367,536 1,753 (15,337 ) 353,952 GNMA commercial mortgage-related securities 516,454 8,092 (26,026 ) 498,520 Total investment securities held to maturity $ 2,661,755 $ 11,223 $ (77,961 ) $ 2,595,017 December 31, 2017 Amortized Gross Gross Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,003 $ — $ (7 ) $ 996 Residential mortgage-related securities FNMA / FHLMC 457,680 9,722 (2,634 ) 464,768 GNMA 1,944,453 275 (31,378 ) 1,913,350 Private-label 1,067 — (8 ) 1,059 GNMA commercial mortgage-related securities 1,547,173 5 (33,901 ) 1,513,277 FFELP asset backed securities 144,322 867 (13 ) 145,176 Other debt securities 3,200 — (12 ) 3,188 Other equity securities 1,519 127 (14 ) 1,632 Total investment securities available for sale $ 4,100,417 $ 10,996 $ (67,967 ) $ 4,043,446 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,281,320 $ 13,899 $ (3,177 ) $ 1,292,042 Residential mortgage-related securities FNMA / FHLMC 40,995 398 (489 ) 40,904 GNMA 414,440 2,700 (6,400 ) 410,740 GNMA commercial mortgage-related securities 546,098 9,546 (15,756 ) 539,888 Total investment securities held to maturity $ 2,282,853 $ 26,543 $ (25,822 ) $ 2,283,574
Investment securities held to maturity	A portion of the portfolio is also comprised of asset-backed securities backed by student loans made under the Federal Family Education Loan Program ("FFELP"). The amortized cost and fair values of securities available for sale and held to maturity were as follows. September 30, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,001 $ — $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 320,148 2,658 (6,132 ) 316,674 GNMA 2,259,538 — (79,528 ) 2,180,010 Private-label 1,022 — (4 ) 1,018 GNMA commercial mortgage-related securities 1,306,802 — (55,824 ) 1,250,978 FFELP asset backed securities 298,282 1,766 (101 ) 299,947 Other debt securities 3,000 — — 3,000 Other equity securities 1,573 — — 1,573 Total investment securities available for sale $ 4,191,366 $ 4,424 $ (141,593 ) $ 4,054,197 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,682,162 $ 1,216 $ (33,332 ) $ 1,650,046 Residential mortgage-related securities FNMA / FHLMC 95,603 162 (3,266 ) 92,499 GNMA 367,536 1,753 (15,337 ) 353,952 GNMA commercial mortgage-related securities 516,454 8,092 (26,026 ) 498,520 Total investment securities held to maturity $ 2,661,755 $ 11,223 $ (77,961 ) $ 2,595,017 December 31, 2017 Amortized Gross Gross Fair Value ($ in Thousands) Investment securities available for sale U. S. Treasury securities $ 1,003 $ — $ (7 ) $ 996 Residential mortgage-related securities FNMA / FHLMC 457,680 9,722 (2,634 ) 464,768 GNMA 1,944,453 275 (31,378 ) 1,913,350 Private-label 1,067 — (8 ) 1,059 GNMA commercial mortgage-related securities 1,547,173 5 (33,901 ) 1,513,277 FFELP asset backed securities 144,322 867 (13 ) 145,176 Other debt securities 3,200 — (12 ) 3,188 Other equity securities 1,519 127 (14 ) 1,632 Total investment securities available for sale $ 4,100,417 $ 10,996 $ (67,967 ) $ 4,043,446 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) $ 1,281,320 $ 13,899 $ (3,177 ) $ 1,292,042 Residential mortgage-related securities FNMA / FHLMC 40,995 398 (489 ) 40,904 GNMA 414,440 2,700 (6,400 ) 410,740 GNMA commercial mortgage-related securities 546,098 9,546 (15,756 ) 539,888 Total investment securities held to maturity $ 2,282,853 $ 26,543 $ (25,822 ) $ 2,283,574
Amortized cost and fair values of investment securities by contractual maturity	The expected maturities of investment securities available for sale and held to maturity at September 30, 2018 are shown below. Expected maturities may 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 Amortized Cost Fair Value Amortized Cost Fair Value ($ in Thousands) Due in one year or less $ 2,001 $ 1,997 $ 48,561 $ 48,871 Due after one year through five years 2,000 2,000 188,337 186,335 Due after five years through ten years — — 385,908 377,705 Due after ten years — — 1,059,355 1,037,135 Total debt securities 4,001 3,997 1,682,162 1,650,046 Residential mortgage-related securities FNMA / FHLMC 320,148 316,674 95,603 92,499 GNMA 2,259,538 2,180,010 367,536 353,952 Private-label 1,022 1,018 — — GNMA commercial mortgage-related securities 1,306,802 1,250,978 516,454 498,520 FFELP asset backed securities 298,282 299,947 — — Equity securities 1,573 1,573 — — Total investment securities $ 4,191,366 $ 4,054,197 $ 2,661,755 $ 2,595,017 Ratio of Fair Value to Amortized Cost 96.7 % 97.5 %
Realized gains and losses and proceeds from sale	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 September 30, 2018 . Less than 12 months 12 months or more Total September 30, 2018 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 U.S. Treasury securities — $ — $ — 1 $ (4 ) $ 997 $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 18 (583 ) 60,527 14 (5,549 ) 172,119 (6,132 ) 232,646 GNMA 47 (29,687 ) 1,150,098 47 (49,841 ) 1,029,912 (79,528 ) 2,180,010 Private-label — — — 1 (4 ) 1,018 (4 ) 1,018 GNMA commercial mortgage-related securities 4 (2,397 ) 63,846 89 (53,427 ) 1,187,406 (55,824 ) 1,251,252 FFELP asset backed securities 6 (101 ) 67,798 — — — (101 ) 67,798 Total 75 $ (32,768 ) $ 1,342,269 152 $ (108,825 ) $ 2,391,452 $ (141,593 ) $ 3,733,721 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) 1,288 $ (22,552 ) $ 1,026,504 228 $ (10,779 ) $ 187,493 $ (33,332 ) $ 1,213,997 Residential mortgage-related securities FNMA / FHLMC 22 (1,798 ) 64,876 18 (1,469 ) 25,980 (3,266 ) 90,856 GNMA 39 (2,676 ) 89,367 46 (12,662 ) 262,952 (15,337 ) 352,319 GNMA commercial mortgage-related securities 1 (951 ) 28,308 24 (25,074 ) 470,212 (26,026 ) 498,520 Total 1,350 $ (27,976 ) $ 1,209,055 316 $ (49,983 ) $ 946,637 $ (77,961 ) $ 2,155,692
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 September 30, 2018 . Less than 12 months 12 months or more Total September 30, 2018 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 U.S. Treasury securities — $ — $ — 1 $ (4 ) $ 997 $ (4 ) $ 997 Residential mortgage-related securities FNMA / FHLMC 18 (583 ) 60,527 14 (5,549 ) 172,119 (6,132 ) 232,646 GNMA 47 (29,687 ) 1,150,098 47 (49,841 ) 1,029,912 (79,528 ) 2,180,010 Private-label — — — 1 (4 ) 1,018 (4 ) 1,018 GNMA commercial mortgage-related securities 4 (2,397 ) 63,846 89 (53,427 ) 1,187,406 (55,824 ) 1,251,252 FFELP asset backed securities 6 (101 ) 67,798 — — — (101 ) 67,798 Total 75 $ (32,768 ) $ 1,342,269 152 $ (108,825 ) $ 2,391,452 $ (141,593 ) $ 3,733,721 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) 1,288 $ (22,552 ) $ 1,026,504 228 $ (10,779 ) $ 187,493 $ (33,332 ) $ 1,213,997 Residential mortgage-related securities FNMA / FHLMC 22 (1,798 ) 64,876 18 (1,469 ) 25,980 (3,266 ) 90,856 GNMA 39 (2,676 ) 89,367 46 (12,662 ) 262,952 (15,337 ) 352,319 GNMA commercial mortgage-related securities 1 (951 ) 28,308 24 (25,074 ) 470,212 (26,026 ) 498,520 Total 1,350 $ (27,976 ) $ 1,209,055 316 $ (49,983 ) $ 946,637 $ (77,961 ) $ 2,155,692 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, 2017 . Less than 12 months 12 months or more Total December 31, 2017 Number Unrealized Fair Number Unrealized Fair Unrealized Fair ($ in Thousands) Investment securities available for sale U.S. Treasury securities 1 $ (7 ) $ 996 — $ — $ — $ (7 ) $ 996 Residential mortgage-related securities FNMA / FHLMC 9 (572 ) 69,939 9 (2,062 ) 142,093 (2,634 ) 212,032 GNMA 44 (8,927 ) 1,028,221 25 (22,451 ) 737,198 (31,378 ) 1,765,419 Private-label — — — 1 (8 ) 1,059 (8 ) 1,059 GNMA commercial mortgage-related securities 33 (5,554 ) 480,514 70 (28,347 ) 1,026,642 (33,901 ) 1,507,156 FFELP asset backed securities 1 (13 ) 12,158 — — — (13 ) 12,158 Other debt securities 1 (12 ) 188 — — — (12 ) 188 Other equity securities 3 (14 ) 1,487 — — — (14 ) 1,487 Total 92 $ (15,099 ) $ 1,593,503 105 $ (52,868 ) $ 1,906,992 $ (67,967 ) $ 3,500,495 Investment securities held to maturity Obligations of state and political subdivisions (municipal securities) 157 $ (746 ) $ 122,761 132 $ (2,431 ) $ 127,043 $ (3,177 ) $ 249,804 Residential mortgage-related securities FNMA / FHLMC 8 (73 ) 13,143 10 (417 ) 16,262 (490 ) 29,405 GNMA 35 (3,373 ) 268,388 18 (3,026 ) 120,892 (6,399 ) 389,280 GNMA commercial mortgage-related securities 2 (299 ) 52,997 23 (15,457 ) 486,891 (15,756 ) 539,888 Total 202 $ (4,491 ) $ 457,289 183 $ (21,331 ) $ 751,088 $ (25,822 ) $ 1,208,377

Loans (Tables)

Loans (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Loan composition	The period end loan composition was as follows. September 30, 2018 (a) December 31, ($ in Thousands) Commercial and industrial $ 7,159,941 $ 6,399,693 Commercial real estate — owner occupied 867,682 802,209 Commercial and business lending 8,027,622 7,201,902 Commercial real estate — investor 3,924,499 3,315,254 Real estate construction 1,416,209 1,451,684 Commercial real estate lending 5,340,708 4,766,938 Total commercial 13,368,330 11,968,840 Residential mortgage 8,227,649 7,546,534 Home equity 901,275 883,804 Other consumer 369,858 385,813 Total consumer 9,498,782 8,816,151 Total loans $ 22,867,112 $ 20,784,991
Commercial and consumer loans by credit quality indicator	The following table presents commercial and consumer loans by credit quality indicator at September 30, 2018 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 6,886,363 $ 78,964 $ 144,468 $ 50,146 $ 7,159,941 Commercial real estate - owner occupied 823,615 6,762 32,526 4,779 867,682 Commercial and business lending 7,709,978 85,725 176,994 54,925 8,027,622 Commercial real estate - investor 3,790,423 64,509 49,842 19,725 3,924,499 Real estate construction 1,401,585 10,078 3,392 1,154 1,416,209 Commercial real estate lending 5,192,008 74,587 53,234 20,879 5,340,708 Total commercial 12,901,986 160,312 230,228 75,804 13,368,330 Residential mortgage 8,154,521 1,159 6,073 65,896 8,227,649 Home equity 887,690 1,113 148 12,324 901,275 Other consumer 369,192 598 — 68 369,858 Total consumer 9,411,403 2,870 6,221 78,288 9,498,782 Total $ 22,313,389 $ 163,182 $ 236,449 $ 154,092 $ 22,867,112 The following table presents commercial and consumer loans by credit quality indicator at December 31, 2017 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 6,015,884 $ 157,245 $ 113,778 $ 112,786 $ 6,399,693 Commercial real estate - owner occupied 723,291 14,181 41,997 22,740 802,209 Commercial and business lending 6,739,175 171,426 155,775 135,526 7,201,902 Commercial real estate - investor 3,266,389 24,845 19,291 4,729 3,315,254 Real estate construction 1,421,504 29,206 — 974 1,451,684 Commercial real estate lending 4,687,893 54,051 19,291 5,703 4,766,938 Total commercial 11,427,068 225,477 175,066 141,229 11,968,840 Residential mortgage 7,490,860 426 1,616 53,632 7,546,534 Home equity 868,958 1,137 195 13,514 883,804 Other consumer 384,990 652 — 171 385,813 Total consumer 8,744,808 2,215 1,811 67,317 8,816,151 Total $ 20,171,876 $ 227,692 $ 176,877 $ 208,546 $ 20,784,991
Summarized details of Loans	The following table presents loans by past due status at September 30, 2018 . Accruing Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Nonaccrual (a) Total ($ in Thousands) Commercial and industrial $ 7,103,744 $ 5,592 $ 140 $ 319 $ 50,146 $ 7,159,941 Commercial real estate - owner occupied 856,777 5,589 537 — 4,779 867,682 Commercial and business lending 7,960,521 11,181 677 319 54,925 8,027,622 Commercial real estate - investor 3,904,401 373 — — 19,725 3,924,499 Real estate construction 1,414,538 517 — — 1,154 1,416,209 Commercial real estate lending 5,318,939 890 — — 20,879 5,340,708 Total commercial 13,279,460 12,071 677 319 75,804 13,368,330 Residential mortgage 8,152,854 7,829 1,070 — 65,896 8,227,649 Home equity 880,871 6,989 1,091 — 12,324 901,275 Other consumer 365,955 1,249 730 1,856 68 369,858 Total consumer 9,399,680 16,067 2,891 1,856 78,288 9,498,782 Total $ 22,679,140 $ 28,138 $ 3,568 $ 2,175 $ 154,092 $ 22,867,112 (a) Of the total nonaccrual loans, $92 million or 60% were current with respect to payment at September 30, 2018 . The following table presents loans by past due status at December 31, 2017 . Accruing Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due Nonaccrual (a) Total ($ in Thousands) Commercial and industrial $ 6,286,369 $ 170 $ 101 $ 267 $ 112,786 $ 6,399,693 Commercial real estate - owner occupied 779,421 48 — — 22,740 802,209 Commercial and business lending 7,065,790 218 101 267 135,526 7,201,902 Commercial real estate - investor 3,310,000 374 — 151 4,729 3,315,254 Real estate construction 1,450,459 168 83 — 974 1,451,684 Commercial real estate lending 4,760,459 542 83 151 5,703 4,766,938 Total commercial 11,826,249 760 184 418 141,229 11,968,840 Residential mortgage 7,483,350 9,186 366 — 53,632 7,546,534 Home equity 863,465 5,688 1,137 — 13,514 883,804 Other consumer 382,186 1,227 780 1,449 171 385,813 Total consumer 8,729,001 16,101 2,283 1,449 67,317 8,816,151 Total $ 20,555,250 $ 16,861 $ 2,467 $ 1,867 $ 208,546 $ 20,784,991 (a) Of the total nonaccrual loans, $135 million or 65% were current with respect to payment at December 31, 2017
Summarized details of impaired Loans	The following table presents impaired loans individually evaluated under ASC Topic 310, excluding $13 million of purchased credit-impaired loans, at September 30, 2018 . Recorded Unpaid Related Average Interest ($ in Thousands) Loans with a related allowance Commercial and industrial $ 57,935 $ 68,894 $ 6,013 $ 70,339 $ 1,121 Commercial real estate — owner occupied 3,746 3,752 20 15,460 143 Commercial and business lending 61,681 72,646 6,033 85,799 1,264 Commercial real estate — investor 2,069 2,148 287 14,929 13 Real estate construction 440 516 74 451 22 Commercial real estate lending 2,509 2,664 361 15,380 35 Total commercial 64,190 75,310 6,394 101,179 1,299 Residential mortgage 40,797 44,197 5,937 41,589 1,321 Home equity 9,692 10,689 3,327 9,846 431 Other consumer 1,186 1,188 123 1,188 2 Total consumer 51,675 56,074 9,387 52,623 1,754 Total loans (a) $ 115,865 $ 131,384 $ 15,781 $ 153,802 $ 3,053 Loans with no related allowance Commercial and industrial $ 28,311 $ 41,615 $ — $ 31,955 $ (348 ) Commercial real estate — owner occupied 3,772 4,823 — 4,043 — Commercial and business lending 32,083 46,438 — 35,998 (348 ) Commercial real estate — investor 9,917 14,230 — 993 892 Real estate construction — — — — — Commercial real estate lending 9,917 14,230 — 993 892 Total commercial 42,000 60,668 — 36,991 544 Residential mortgage 9,925 10,047 — 10,504 172 Home equity 778 796 — 1,277 5 Other consumer — — — — — Total consumer 10,703 10,843 — 11,781 177 Total loans (a) $ 52,703 $ 71,511 $ — $ 48,772 $ 721 Total Commercial and industrial $ 86,246 $ 110,509 $ 6,013 $ 102,294 $ 773 Commercial real estate — owner occupied 7,518 8,575 20 19,503 143 Commercial and business lending 93,764 119,084 6,033 121,797 916 Commercial real estate — investor 11,986 16,378 287 15,922 905 Real estate construction 440 516 74 451 22 Commercial real estate lending 12,426 16,894 361 16,373 927 Total commercial 106,190 135,978 6,394 138,170 1,843 Residential mortgage 50,722 54,244 5,937 52,093 1,493 Home equity 10,470 11,485 3,327 11,123 436 Other consumer 1,186 1,188 123 1,188 2 Total consumer 62,378 66,917 9,387 64,404 1,931 Total loans (a) $ 168,568 $ 202,895 $ 15,781 $ 202,574 $ 3,774 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 75% of the unpaid principal balance at September 30, 2018 . The following table presents impaired loans individually evaluated under ASC Topic 310 at December 31, 2017 . Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized ($ in Thousands) Loans with a related allowance Commercial and industrial $ 81,649 $ 83,579 $ 10,838 $ 58,494 $ 2,629 Commercial real estate — owner occupied 23,796 23,937 2,973 12,124 736 Commercial and business lending 105,445 107,516 13,811 70,618 3,365 Commercial real estate — investor 17,823 17,862 1,597 16,924 1,694 Real estate construction 467 578 86 484 29 Commercial real estate lending 18,290 18,440 1,683 17,408 1,723 Total commercial 123,735 125,956 15,494 88,026 5,088 Residential mortgage 40,561 42,922 6,512 40,411 1,614 Home equity 10,250 10,986 3,718 10,521 549 Other consumer 1,135 1,138 122 1,140 3 Total consumer 51,946 55,046 10,352 52,072 2,166 Total loans (a) $ 175,681 $ 181,002 $ 25,846 $ 140,098 $ 7,254 Loans with no related allowance Commercial and industrial $ 60,595 $ 82,839 $ — $ 89,275 $ 492 Commercial real estate — owner occupied 2,438 2,829 — 1,948 36 Commercial and business lending 63,033 85,668 — 91,223 528 Commercial real estate — investor 1,295 1,295 — — 45 Real estate construction — — — — — Commercial real estate lending 1,295 1,295 — — 45 Total commercial 64,328 86,963 — 91,223 573 Residential mortgage 6,925 7,204 — 4,999 217 Home equity 641 645 — 540 7 Other consumer — — — — — Total consumer 7,566 7,849 — 5,539 224 Total loans (a) $ 71,894 $ 94,812 $ — $ 96,762 $ 797 Total Commercial and industrial $ 142,244 $ 166,418 $ 10,838 $ 147,769 $ 3,121 Commercial real estate — owner occupied 26,234 26,766 2,973 14,072 772 Commercial and business lending 168,478 193,184 13,811 161,841 3,893 Commercial real estate — investor 19,118 19,157 1,597 16,924 1,739 Real estate construction 467 578 86 484 29 Commercial real estate lending 19,585 19,735 1,683 17,408 1,768 Total commercial 188,063 212,919 15,494 179,249 5,661 Residential mortgage 47,486 50,126 6,512 45,410 1,831 Home equity 10,891 11,631 3,718 11,061 556 Other consumer 1,135 1,138 122 1,140 3 Total consumer 59,512 62,895 10,352 57,611 2,390 Total loans (a) $ 247,575 $ 275,814 $ 25,846 $ 236,860 $ 8,051 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 80% of the unpaid principal balance at December 31, 2017 .
Nonaccrual and performing restructured loans	The following table presents nonaccrual and performing restructured loans by loan portfolio. September 30, 2018 December 31, 2017 Performing Restructured Loans Nonaccrual Restructured Loans (a) Performing Restructured Loans Nonaccrual Restructured Loans (a) ($ in Thousands) Commercial and industrial $ 38,885 $ 142 $ 30,047 $ 1,776 Commercial real estate — owner occupied 3,746 — 3,989 — Commercial real estate — investor 350 9,917 14,389 — Real estate construction 218 222 310 157 Residential mortgage 16,986 20,952 17,068 18,991 Home equity 7,792 2,515 7,705 2,537 Other consumer 1,177 9 1,110 25 Total $ 69,154 $ 33,757 $ 74,618 $ 23,486 (a)
Summary of restructured loans	Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 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 6 $ 1,954 $ 1,995 19 $ 11,387 $ 15,898 Commercial real estate — owner occupied — — — 2 710 710 Commercial real estate — investor 1 958 1,022 — — — Residential mortgage 29 5,655 5,733 48 4,445 4,638 Home equity 32 1,552 1,582 35 934 1,182 Other consumer 3 19 21 — — — Total 71 $ 10,138 $ 10,353 104 $ 17,476 $ 22,428 (a) Represents post-modification outstanding recorded investment. (b)
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 nine months ended September 30, 2018 and 2017 and the recorded investment in these restructured loans as of September 30, 2018 and 2017 . Nine Months Ended September 30, 2018 Nine Months Ended September 30, 2017 Number of Loans Recorded Investment Number of Loans Recorded Investment ($ in Thousands) Commercial and industrial 3 $ — 1 $ 1 Residential mortgage 12 2,579 21 1,335 Home equity 28 1,599 14 371 Total 43 $ 4,178 36 $ 1,707
Changes in the allowance for loan losses by portfolio segment	The following table presents a summary of the changes in the allowance for loan losses by portfolio segment for the nine months ended September 30, 2018 . ($ in Thousands) Commercial and Commercial real estate - owner occupied Commercial real estate - Real estate Residential Home Other Total December 31, 2017 $ 123,068 $ 10,352 $ 41,059 $ 34,370 $ 29,607 $ 22,126 $ 5,298 $ 265,880 Charge offs (29,707 ) (1,361 ) (5,278 ) (298 ) (1,310 ) (2,508 ) (3,923 ) (44,385 ) Recoveries 9,609 354 139 340 1,049 2,171 593 14,255 Net Charge offs (20,098 ) (1,007 ) (5,139 ) 42 (261 ) (337 ) (3,330 ) (30,130 ) Provision for loan losses 2,643 105 5,737 (7,676 ) (1,884 ) (2,101 ) 3,676 500 September 30, 2018 $ 105,613 $ 9,451 $ 41,657 $ 26,737 $ 27,461 $ 19,687 $ 5,644 $ 236,250 Allowance for loan losses Individually evaluated for impairment $ 6,013 $ 20 $ 287 $ 74 $ 5,937 $ 3,327 $ 123 $ 15,781 Collectively evaluated for impairment 99,600 9,431 41,370 26,663 21,524 16,360 5,521 220,469 Acquired and accounted for under ASC 310-30 (a) — — — — — — — — Total allowance for loan losses $ 105,613 $ 9,451 $ 41,657 $ 26,737 $ 27,461 $ 19,687 $ 5,644 $ 236,250 Loans Individually evaluated for impairment $ 86,246 $ 7,518 $ 11,986 $ 440 $ 50,722 $ 10,470 $ 1,186 $ 168,568 Collectively evaluated for impairment 7,071,043 858,747 3,904,266 1,415,745 8,176,217 890,721 368,672 22,685,411 Acquired and accounted for under ASC 310-30 (a) 2,652 1,416 8,247 24 710 84 — 13,133 Total loans $ 7,159,941 $ 867,682 $ 3,924,499 $ 1,416,209 $ 8,227,649 $ 901,275 $ 369,858 $ 22,867,112 (a) Loans acquired in business combinations and accounted for under ASC Subtopic 310-30 "Receivables — Loans and Debt Securities Acquired with Deteriorated Credit Quality." For comparison purposes, a summary of the changes in the allowance for loan losses by portfolio segment for the year ended December 31, 2017 , was as follows. ($ in Thousands) Commercial and Commercial real estate Commercial real estate - Real estate Residential Home Other Total December 31, 2016 $ 140,126 $ 14,034 $ 45,285 $ 26,932 $ 27,046 $ 20,364 $ 4,548 $ 278,335 Charge offs (44,533 ) (344 ) (991 ) (604 ) (2,611 ) (2,724 ) (4,439 ) (56,246 ) Recoveries 11,465 173 242 74 927 3,194 716 16,791 Net Charge offs (33,068 ) (171 ) (749 ) (530 ) (1,684 ) 470 (3,723 ) (39,455 ) Provision for loan losses 16,010 (3,511 ) (3,477 ) 7,968 4,245 1,292 4,473 27,000 December 31, 2017 $ 123,068 $ 10,352 $ 41,059 $ 34,370 $ 29,607 $ 22,126 $ 5,298 $ 265,880 Allowance for loan losses Individually evaluated for impairment $ 10,838 $ 2,973 $ 1,597 $ 86 $ 6,512 $ 3,718 $ 122 $ 25,846 Collectively evaluated for impairment 112,230 7,379 39,462 34,284 23,095 18,408 5,176 240,034 Total allowance for loan losses $ 123,068 $ 10,352 $ 41,059 $ 34,370 $ 29,607 $ 22,126 $ 5,298 $ 265,880 Loans Individually evaluated for impairment $ 142,244 $ 26,234 $ 19,118 $ 467 $ 47,486 $ 10,891 $ 1,135 $ 247,575 Collectively evaluated for impairment 6,257,449 775,975 3,296,136 1,451,217 7,499,048 872,913 384,678 20,537,416 Total loans $ 6,399,693 $ 802,209 $ 3,315,254 $ 1,451,684 $ 7,546,534 $ 883,804 $ 385,813 $ 20,784,991 ($ in Millions) Nine Months Ended September 30, 2018 Year Ended December 31, 2017 Balance at beginning of period $ 27 $ 38 Charge offs (24 ) (25 ) Recoveries 3 — Net Charge offs (20 ) (25 ) Provision for loan losses 3 14 Balance at end of period $ 10 $ 27 Allowance for loan losses Individually evaluated for impairment $ — $ 5 Collectively evaluated for impairment 10 22 Total allowance for loan losses $ 10 $ 27 Loans Individually evaluated for impairment $ 32 $ 77 Collectively evaluated for impairment 700 523 Total loans $ 731 $ 600
Changes in the allowance for unfunded commitments	The following table presents a summary of the changes in the allowance for unfunded commitments. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Allowance for Unfunded Commitments Balance at beginning of period $ 24,400 $ 25,400 Provision for unfunded commitments (1,500 ) (1,000 ) Amount recorded at acquisition 2,436 — Balance at end of period $ 25,336 $ 24,400
Changes In Accretable Yield For Purchased Credit Impaired	Changes in the accretable yield for loans acquired and accounted for under ASC Topic 310-30 were as follows for the nine months ended September 30, 2018 and for the year ended December 31, 2017 Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Changes in Accretable Yield Balance at beginning of period $ — $ — Purchases 4,853 — Accretion (310 ) — Net reclassification from non-accretable yield 144 — Other (a) (5 ) — Balance at end of period $ 4,681 $ —

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
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. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Core deposit intangibles Gross carrying amount $ 58,100 $ 4,385 Accumulated amortization (3,873 ) (4,385 ) Net book value $ 54,227 $ — Additions during the periods $ 58,100 $ — Amortization during the year $ 3,873 $ 112 Other intangibles Gross carrying amount $ 44,931 $ 34,572 Reductions due to sale (43 ) — Accumulated amortization (21,045 ) (18,992 ) Net book value $ 23,843 $ 15,580 Additions during the period $ 10,359 $ 2,162 Amortization during the year $ 2,053 $ 1,847
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. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Mortgage servicing rights Mortgage servicing rights at beginning of period $ 59,168 $ 62,085 Additions from acquisition 8,136 — Additions 7,826 7,167 Amortization (7,143 ) (10,084 ) Mortgage servicing rights at end of period $ 67,987 $ 59,168 Valuation allowance at beginning of period (784 ) (609 ) (Additions) recoveries, net 669 (175 ) Valuation allowance at end of period (115 ) (784 ) Mortgage servicing rights, net $ 67,872 $ 58,384 Fair value of mortgage servicing rights $ 87,120 $ 64,387 Portfolio of residential mortgage loans serviced for others (“servicing portfolio”) $ 8,547,230 $ 7,646,846 Mortgage servicing rights, net to servicing portfolio 0.79 % 0.76 % Mortgage servicing rights expense (a) $ 6,474 $ 10,259 (a)
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 September 30, 2018 . 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) Three Months Ending December 31, 2018 $ 1,453 $ 780 $ 2,362 2019 5,810 2,824 9,029 2020 5,810 2,707 7,892 2021 5,810 2,682 6,873 2022 5,810 2,659 5,995 2023 5,810 2,640 5,246 Beyond 2023 23,724 9,551 30,590 Total Estimated Amortization Expense $ 54,227 $ 23,843 $ 67,987

Short and Long-Term Funding (Ta

Short and Long-Term Funding (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Breakdown of short & long-term debt balances	The following table presents the components of short-term funding (funding with original contractual maturities of one year or less), long-term funding (funding with original contractual maturities greater than one year), and FHLB advances (funding based on original contractual maturities). September 30, 2018 December 31, 2017 ($ in Thousands) Short-Term Funding Federal funds purchased $ 25,890 $ 141,950 Securities sold under agreements to repurchase 140,666 182,865 Federal funds purchased and securities sold under agreements to repurchase 166,556 324,815 Commercial paper 43,604 67,467 Total short-term funding $ 210,159 $ 392,282 Long-Term Funding Senior notes, at par $ 550,000 $ 250,000 Subordinated notes, at par 250,000 250,000 Other long-term funding and capitalized costs (4,785 ) (2,718 ) Total long-term funding 795,215 497,282 Total short and long-term funding, excluding FHLB advances $ 1,005,375 $ 889,564 FHLB Advances Short-term FHLB advances $ 405,000 $ 284,000 Long-term FHLB advances 2,927,655 2,900,168 Total FHLB advances $ 3,332,655 $ 3,184,168 Total short and long-term funding $ 4,338,030 $ 4,073,732
Remaining contractual maturity of securities sold under agreements to repurchase	The remaining contractual maturity of the securities sold under agreements to repurchase in the consolidated balance sheets as of September 30, 2018 and December 31, 2017 are presented in the following table. Remaining Contractual Maturity of the Agreements Overnight and Continuous Up to 30 days 30-90 days Greater than 90 days Total ($ in Thousands) September 30, 2018 Repurchase agreements Agency mortgage-related securities $ 140,666 $ — $ — $ — $ 140,666 Total $ 140,666 $ — $ — $ — $ 140,666 December 31, 2017 Repurchase agreements Agency mortgage-related securities $ 182,865 $ — $ — $ — $ 182,865 Total $ 182,865 $ — $ — $ — $ 182,865
FHLB_Maturity_ [Table Text Block]	The original contractual maturity or next put date of the Corporation's FHLB advances as of September 30, 2018 and December 31, 2017 are presented in the following table. September 30, 2018 December 31, 2017 Amount Weighted Average Contractual Coupon Rate Amount Weighted Average Contractual Coupon Rate ($ in Thousands) Maturity or put date 1 year or less $ 1,371,059 1.76 % $ 2,434,000 1.26 % After 1 but within 2 1,662,019 2.29 % 750,013 1.23 % After 2 but within 3 216,289 2.53 % 155 4.91 % After 3 years 83,289 2.62 % — — % FHLB advances and overall rate $ 3,332,655 2.10 % $ 3,184,168 1.26 %

Derivative and Hedging Activi_2

Derivative and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary Of Other derivative instruments not designated as hedging instruments	The table below identifies the balance sheet category and fair values of the Corporation’s derivative instruments. September 30, 2018 December 31, 2017 ($ in Thousands) Notional Amount Fair Balance Sheet Notional Amount Fair Balance Sheet Derivatives not designated as hedging instruments Interest rate-related instruments — customer and mirror $ 2,712,813 $ 68,916 Trading assets $ 2,183,687 $ 28,494 Trading assets Interest rate-related instruments — customer and mirror 2,712,813 (68,103 ) Trading liabilities 2,183,687 (28,035 ) Trading liabilities Foreign currency exchange forwards 124,137 1,974 Trading assets 124,851 2,495 Trading assets Foreign currency exchange forwards 119,748 (1,840 ) Trading liabilities 118,094 (2,339 ) Trading liabilities Commodity contracts 401,849 69,439 Trading assets 457,868 38,686 Trading assets Commodity contracts 401,968 (68,997 ) Trading liabilities 457,108 (37,286 ) Trading liabilities Interest rate lock commitments (mortgage) 259,762 1,685 Other assets 222,736 1,538 Other assets Forward commitments (mortgage) 271,561 1,352 Other assets 164,567 (313 ) Other liabilities Purchased options (time deposit) 21,269 577 Other assets 31,063 1,175 Other assets Written options (time deposit) 21,269 (577 ) Other liabilities 31,063 (1,175 ) Other liabilities Derivatives designated as hedging instruments Interest Rate Products 500,000 4,902 Other assets — — —
Cumulative Basis Adjustment for Fair Value Hedges	The following table presents amounts that were recorded on the balance sheet related to cumulative basis adjustment for fair value hedges. Line Item in the Statement of Financial Position in Which the Hedged Item is Included Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) ($ in Thousands) September 30, 2018 Loans and investment securities receivables (a) $ 495,069 $ (4,931 ) Total $ 495,069 $ (4,931 ) (a) These amounts include the amortized cost basis of closed portfolios used to designated hedging relationships in which the hedged item is the last layer expected to be remaining at the end of the hedging relationship. At September 30, 2018, the amortized cost basis of the closed portfolios used in these hedging relationships was $1.1 billion ; the negative cumulative basis adjustments associated with these hedging relationships was $5 million; and the amounts of the designated hedged items were $500 million
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The table below identifies the effect of fair value hedge accounting on the Corporation's statement of performance during the nine months ended September 30, 2018 . Location and Amount of Gain or (Loss) Recognized in Income on Fair Value and Cash Flow Hedging Relationships Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Interest Income Other Income (Expense) Interest Income Other Income (Expense) Total amounts of income and expense line items presented in the statement of financial performance in which the effects of fair value or cash flow hedges are recorded $ (30 ) $ — $ — $ — The effects of fair value and cash flow hedging: Gain or (loss) on fair value hedging relationships in Subtopic 815-20 Interest contracts Hedged items (4,931 ) — — — Derivatives designated as hedging instruments 4,902 — — —
Gain (loss) on derivative instruments not designated as hedging instruments	The table below identifies the effect of derivatives not designated as hedging instruments on the Corporation's statement of income during the nine months ended September 30, 2018 . Income Statement Category of Gain / (Loss) Recognized in Income For the Nine Months Ended September 30, ($ in Thousands) 2018 2017 Derivative Instruments Interest rate-related instruments — customer and mirror, net Capital markets, net $ 354 $ (115 ) Interest rate lock commitments (mortgage) Mortgage banking, net 147 2,523 Forward commitments (mortgage) Mortgage banking, net 1,665 (2,674 ) Foreign currency exchange forwards Capital markets, net (22 ) (39 ) Commodity contracts Capital markets, net (958 ) 476

Balance Sheet Offsetting (Table

Balance Sheet Offsetting (Tables)	9 Months Ended
	Sep. 30, 2018
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 the Corporation has with its commercial customers are not subject to an enforceable master netting arrangement, and therefore, are excluded from this table. Gross amounts of recognized assets Gross amounts not offset in the balance sheet ($ in Thousands) Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Derivative liability available for offset Collateral received Net amount Derivative assets: (a) September 30, 2018 $ 78,124 $ — $ 78,124 $ (26,385 ) $ (50,134 ) $ 1,605 December 31, 2017 29,503 — 29,503 (16,140 ) (13,234 ) 129 Gross amounts of recognized liabilities Gross amounts not offset in the balance sheet ($ in Thousands) Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Derivative asset available for offset Collateral pledged Net amount Derivative liabilities (b) September 30, 2018 $ 64,591 $ — $ 64,591 $ (26,385 ) $ (37,480 ) $ 726 December 31, 2017 37,164 — 37,164 (16,140 ) (20,662 ) 362 (a) Includes interest and commodity instrument assets. (b) Includes interest and commodity instrument liabilities.

Commitments, Off-Balance Shee_2

Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Summary of lending-related and other commitments	The following is a summary of lending-related commitments. September 30, 2018 December 31, 2017 ($ in Thousands) Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale (a)(b) $ 8,471,141 $ 8,027,187 Commercial letters of credit (a) 9,122 11,886 Standby letters of credit (c) 260,092 235,361 (a) 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 September 30, 2018 or December 31, 2017 . (b) Interest rate lock commitments to originate residential mortgage loans held for sale are considered derivative instruments and are disclosed in Note 10 . (c) The Corporation has established a liability of $3 million at September 30, 2018 and $2 million at December 31, 2017
Summary of changes in the residential mortgage repurchase reserve	The following summarizes the changes in the mortgage repurchase reserve. Nine Months Ended September 30, 2018 Year Ended December 31, 2017 ($ in Thousands) Balance at beginning of period $ 987 $ 900 Repurchase provision expense 254 246 Charge offs, net (125 ) (159 ) Amount recorded at acquisition 88 — Balance at end of period $ 1,204 $ 987

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured on Recurring Basis at Fair Value	The table below presents the Corporation’s financial instruments measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 , aggregated by the level in the fair value hierarchy within which those measurements fall. Fair Value Hierarchy September 30, 2018 December 31, 2017 ($ in Thousands) Assets Investment securities available for sale U.S. Treasury securities Level 1 $ 997 $ 996 Residential mortgage-related securities FNMA / FHLMC Level 2 316,674 464,768 GNMA Level 2 2,180,010 1,913,350 Private-label Level 2 1,018 1,059 GNMA commercial mortgage-related securities Level 2 1,250,978 1,513,277 FFELP asset backed securities Level 2 299,947 145,176 Other equity securities Level 1 1,573 1,632 Other debt securities Level 2 3,000 3,188 Total investment securities available for sale Level 1 2,570 2,628 Total investment securities available for sale Level 2 4,051,627 4,040,818 Residential loans held for sale Level 2 134,361 85,544 Commercial loans held for sale Level 2 30,452 — Interest rate-related instruments Level 2 68,916 28,494 Foreign currency exchange forwards Level 2 1,974 2,495 Interest rate products (designated as hedging instruments) Level 2 4,902 — Interest rate lock commitments to originate residential mortgage loans held for sale Level 3 1,685 1,538 Forward commitments to sell residential mortgage loans Level 3 1,352 — Commodity contracts Level 2 69,439 38,686 Purchased options (time deposit) Level 2 577 1,175 Liabilities Interest rate-related instruments Level 2 $ 68,103 $ 28,035 Foreign currency exchange forwards Level 2 1,840 2,339 Forward commitments to sell residential mortgage loans Level 3 — 313 Commodity contracts Level 2 68,997 37,286 Written options (time deposit) Level 2 577 1,175
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 nine months ended September 30, 2018 and the year ended December 31, 2017 , 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, 2016 $ 200 $ 3,114 Total net gains (losses) included in income Mortgage derivative gain (loss) — (1,889 ) Transfer out of level 3 securities (a) (200 ) — Balance December 31, 2017 $ — $ 1,225 Total net gains (losses) included in income Mortgage derivative gain (loss) — 1,816 Balance September 30, 2018 $ — $ 3,041 (a) During the first quarter of 2017, the $200,000
Assets and Liabilities Measured on Nonrecurring Basis at Fair Value	The table below presents the Corporation’s assets measured at fair value on a nonrecurring basis, aggregated by the level in the fair value hierarchy within which those measurements fall. Income Statement Category of Adjustment Recognized in Income ($ in Thousands) Fair Value Hierarchy Fair Value September 30, 2018 Assets Impaired loans (a) Level 3 $ 39,438 Provision for credit losses (b) $ (13,183 ) Other real estate owned (c) Level 2 2,688 Foreclosure / OREO expense, net (965 ) Mortgage servicing rights Level 3 87,120 Mortgage banking, net 669 December 31, 2017 Assets Impaired loans (a) Level 3 $ 92,534 Provision for credit losses (b) $ (32,159 ) Other real estate owned (c) Level 2 2,604 Foreclosure / OREO expense, net (939 ) Mortgage servicing rights Level 3 64,387 Mortgage banking, net (175 )
Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Table Text Block]	The table below presents information about these inputs and further discussion is found above. Valuation Technique Significant Unobservable Input Weighted Average Input Applied September 30, 2018 Mortgage servicing rights Discounted cash flow Discount rate 11% Mortgage servicing rights Discounted cash flow Constant prepayment rate 8% Impaired Loans Appraisals / Discounted cash flow Collateral / Discount factor 34%
Estimated fair values of financial instruments	Fair value estimates are set forth below for the Corporation’s financial instruments. September 30, 2018 December 31, 2017 Fair Value Hierarchy Level Carrying Amount Fair Value Carrying Amount Fair Value ($ in Thousands) Financial assets Cash and due from banks Level 1 $ 374,168 $ 374,168 $ 483,666 $ 483,666 Interest-bearing deposits in other financial institutions Level 1 147,848 147,848 199,702 199,702 Federal funds sold and securities purchased under agreements to resell Level 1 24,325 24,325 32,650 32,650 Investment securities held to maturity Level 2 2,661,755 2,595,017 2,282,853 2,283,574 Investment securities available for sale Level 1 2,570 2,570 2,628 2,628 Investment securities available for sale Level 2 4,051,627 4,051,627 4,040,818 4,040,818 FHLB and Federal Reserve Bank stocks Level 2 220,825 220,825 165,331 165,331 Residential loans held for sale Level 2 134,361 134,361 85,544 85,544 Commercial loans held for sale Level 2 30,452 30,452 — — Loans, net Level 3 22,630,861 22,140,169 20,519,111 20,314,984 Bank and corporate owned life insurance Level 2 661,009 661,009 591,057 591,057 Derivatives (trading and other assets) Level 2 145,808 145,808 70,850 70,850 Derivatives (trading and other assets) Level 3 3,037 3,037 1,538 1,538 Financial liabilities Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts Level 3 $ 21,542,860 $ 21,542,860 $ 20,436,893 $ 20,436,893 Brokered CDs and other time deposits (a) Level 2 3,288,752 3,288,752 2,349,069 2,349,069 Short-term funding (b) Level 2 615,159 615,159 676,282 676,282 Long-term funding Level 2 3,722,870 3,719,147 3,397,450 3,411,368 Standby letters of credit (c) Level 2 2,600 2,600 2,402 2,402 Derivatives (trading and other liabilities) Level 2 139,517 139,517 68,835 68,835 Derivatives (trading and other liabilities) Level 3 — — 313 313 (a) When the estimated fair value is less than the carrying value, the carrying value is reported as the fair value. (b) The carrying amount is a reasonable estimate of fair value for existing short-term funding. (c) The commitment on standby letters of credit was $260 million and $235 million at September 30, 2018 and December 31, 2017

Retirement Plans (Tables)

Retirement Plans (Tables)	9 Months Ended
	Sep. 30, 2018
Defined Benefit Plan [Abstract]
Net period benefit cost for the pension and postretirement plans	The components of net periodic benefit cost for the RAP, Bank Mutual Pension Plan, and Postretirement Plan for three and nine months ended September 30, 2018 and 2017 were as follows. Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Components of Net Periodic Benefit Cost RAP Service cost $ 1,885 $ 1,713 $ 5,670 $ 5,276 Interest cost 1,682 1,795 5,002 5,307 Expected return on plan assets (4,777 ) (4,929 ) (14,287 ) (14,692 ) Amortization of prior service cost (18 ) (19 ) (56 ) (56 ) Amortization of actuarial loss 549 619 1,474 1,594 Total net pension cost $ (680 ) $ (821 ) $ (2,197 ) $ (2,571 ) Bank Mutual Pension Plan (a) Interest cost $ 654 N/A $ 1,737 N/A Expected return on plan assets (1,220 ) N/A (2,812 ) N/A Total net pension cost $ (566 ) N/A $ (1,075 ) N/A Postretirement Plan (b) Interest cost $ 27 $ 26 $ 80 $ 74 Amortization of prior service cost (19 ) (19 ) (56 ) (57 ) Amortization of actuarial loss 2 2 6 2 Total net periodic benefit cost $ 11 $ 9 $ 30 $ 19

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting Information [Line Items]
Selected segment information	Information about the Corporation’s segments is presented below. Corporate and Commercial Specialty Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 113,298 $ 93,114 $ 339,718 $ 270,256 Net intersegment interest income (expense) (13,018 ) (758 ) (36,151 ) 1,359 Segment net interest income 100,280 92,356 303,567 271,615 Noninterest income 12,280 12,278 39,156 36,768 Total revenue 112,560 104,634 342,723 308,383 Credit provision (a) 11,232 9,499 32,955 32,549 Noninterest expense 41,828 39,681 122,853 116,578 Income (loss) before income taxes 59,500 55,454 186,914 159,256 Income tax expense (benefit) 12,098 19,070 36,978 53,082 Net income $ 47,402 $ 36,384 $ 149,937 $ 106,174 Return on average allocated capital (ROCET1) (b) 15.5 % 12.8 % 16.6 % 12.7 % Average earning assets $ 11,981,760 $ 10,923,762 $ 11,814,674 $ 10,846,418 Average loans 11,974,090 10,916,829 11,804,458 10,837,933 Average deposits 8,695,170 7,398,970 8,127,134 6,759,105 Average allocated capital (CET1) (b) 1,215,331 1,125,181 1,207,925 1,121,800 Allocated goodwill 524,525 428,000 Community, Consumer, and Business Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 91,323 $ 81,058 $ 268,137 $ 236,407 Net intersegment interest income (expense) 21,951 9,894 63,301 33,603 Segment net interest income 113,275 90,952 331,438 270,011 Noninterest income 73,838 67,867 224,109 198,546 Total revenue 187,113 158,819 555,547 468,557 Credit provision (a) 5,280 5,046 15,125 15,317 Noninterest expense 139,653 120,241 405,338 361,580 Income (loss) before income taxes 42,180 33,532 135,084 91,660 Income tax expense (benefit) 8,861 11,736 28,371 32,081 Net income $ 33,319 $ 21,796 $ 106,713 $ 59,579 Return on average allocated capital (ROCET1) (b) 20.0 % 14.7 % 21.9 % 13.6 % Average earning assets $ 10,456,159 $ 9,608,242 $ 10,333,412 $ 9,418,173 Average loans 10,453,485 9,602,098 10,329,888 9,414,880 Average deposits 13,716,862 11,788,606 13,518,903 11,568,220 Average allocated capital (CET1) (b) 662,017 588,841 652,745 584,774 Allocated goodwill 644,397 544,006 Risk Management and Shared Services Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 14,770 $ 15,951 $ 47,770 $ 47,552 Net intersegment interest income (expense) (8,933 ) (9,136 ) (27,150 ) (34,963 ) Segment net interest income 5,837 6,814 20,620 12,589 Noninterest income 2,183 5,750 8,257 12,822 Total revenue 8,019 12,564 28,876 25,411 Credit provision (a) (21,512 ) (9,545 ) (49,081 ) (21,866 ) Noninterest expense (c) 22,932 17,505 100,445 49,276 Income (loss) before income taxes 6,599 4,604 (22,488 ) (1,999 ) Income tax expense (benefit) 1,390 (2,217 ) (10,416 ) (15,500 ) Net income $ 5,209 $ 6,821 $ (12,072 ) $ 13,501 Return on average allocated capital (ROCET1) (b) 1.8 % 4.4 % (4.2 )% 2.2 % Average earning assets $ 8,036,951 $ 6,927,791 $ 7,912,853 $ 6,587,401 Average loans 546,142 380,210 554,824 248,165 Average deposits 2,283,886 3,253,869 2,355,566 3,486,354 Average allocated capital (CET1) (b) 635,924 405,653 603,684 387,388 Consolidated Total Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 ($ in Thousands) Net interest income $ 219,392 $ 190,122 $ 655,625 $ 554,215 Net intersegment interest income (expense) — — — — Segment net interest income 219,392 190,122 655,625 554,215 Noninterest income 88,300 85,895 271,522 248,136 Total revenue 307,692 276,017 927,146 802,351 Credit provision (a) (5,000 ) 5,000 (1,000 ) 26,000 Noninterest expense 204,413 177,427 628,636 527,434 Income (loss) before income taxes 108,279 93,590 299,510 248,917 Income tax expense (benefit) 22,349 28,589 54,932 69,663 Net income $ 85,929 $ 65,001 $ 244,578 $ 179,254 Return on average allocated capital (ROCET1) (b) 13.2 % 11.7 % 12.9 % 11.0 % Average earning assets $ 30,474,870 $ 27,459,795 $ 30,060,938 $ 26,851,992 Average loans 22,973,717 20,899,137 22,689,170 20,500,978 Average deposits 24,695,918 22,441,445 24,001,604 21,813,679 Average allocated capital (CET1) (b) 2,513,272 2,119,675 2,464,354 2,093,962 Allocated goodwill 1,168,922 972,006 (a) The consolidated credit provision is equal to the actual reported provision for credit losses. (b) The Federal Reserve establishes capital adequacy requirements for the Corporation, including common equity Tier 1. For segment reporting purposes, the return on common equity Tier 1 ("ROCET1") reflects return on average allocated common equity Tier 1. 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. (c) For the three months ended September 30, 2018, the Risk Management and Shared Services segment includes approximately $2 million of acquisition related noninterest expense. For the nine months ended September 30, 2018, the Risk Management and Shared Services segment includes approximately $30 million

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Summary of activity in accumulated other comprehensive income (loss)	The following tables summarize the components of accumulated other comprehensive income (loss) at September 30, 2018 and 2017 respectively, including changes during the preceding nine and three month periods as well as any reclassifications out of accumulated other comprehensive income (loss). ($ in Thousands) Investment Securities Available For Sale Defined Benefit Pension and Post Retirement Obligations Accumulated Other Comprehensive Income (Loss) Balance January 1, 2018 $ (38,453 ) $ (24,305 ) $ (62,758 ) Other comprehensive income (loss) before reclassifications (82,099 ) — (82,099 ) Amounts reclassified from accumulated other comprehensive income (loss) Investment securities losses (gains), net 1,985 — 1,985 Personnel expense — (112 ) (112 ) Other expense — 1,480 1,480 Adjustment for adoption of ASU 2016-01 (84 ) — (84 ) Adjustment for adoption of ASU 2018-02 (8,419 ) (5,235 ) (13,654 ) Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) (684 ) — (684 ) Income tax (expense) benefit 20,796 (390 ) 20,406 Net other comprehensive income (loss) during period (68,505 ) (4,257 ) (72,762 ) Balance September 30, 2018 $ (106,958 ) $ (28,562 ) $ (135,520 ) Balance January 1, 2017 $ (20,079 ) $ (34,600 ) $ (54,679 ) Other comprehensive income (loss) before reclassifications 1,646 — 1,646 Amounts reclassified from accumulated other comprehensive income (loss) Personnel expense — (113 ) (113 ) Other expense — 1,596 1,596 Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) (2,499 ) — (2,499 ) Income tax (expense) benefit 328 (567 ) (239 ) Net other comprehensive income (loss) during period (525 ) 916 391 Balance September 30, 2017 $ (20,604 ) $ (33,684 ) $ (54,288 ) ($ in Thousands) Investments Defined Benefit Accumulated Balance July 1, 2018 $ (90,986 ) $ (28,902 ) $ (119,888 ) Other comprehensive income (loss) before reclassifications (21,345 ) — (21,345 ) Amounts reclassified from accumulated other comprehensive income (loss) Investment securities losses (gains), net (30 ) — (30 ) Personnel expense — (37 ) (37 ) Other expense — 551 551 Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities) (52 ) — (52 ) Income tax (expense) benefit 5,456 (174 ) 5,282 Net other comprehensive income (loss) during period (15,971 ) 340 (15,631 ) September 30, 2018 $ (106,958 ) $ (28,562 ) $ (135,520 ) Balance July 1, 2017 $ (19,428 ) $ (34,042 ) $ (53,470 ) Other comprehensive income (loss) before reclassifications (1,986 ) — (1,986 ) Amounts reclassified from accumulated other comprehensive income (loss) Personnel expense — (38 ) (38 ) Other expense — 621 621 Interest income (Amortization of net unrealized losses (gains)on available for sale securities transferred to held to maturity securities) 76 — 76 Income tax (expense) benefit 734 (225 ) 509 Net other comprehensive income (loss) during period (1,176 ) 358 (818 ) September 30, 2017 $ (20,604 ) $ (33,684 ) $ (54,288 )

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue Recognition [Abstract]
Disaggregation of Revenue by Major Source	The following table disaggregates the Corporation's revenue by major source for the three and nine months ended September 30, 2018 and 2017 . Nine Months Ended September 30, 2018 ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Insurance commissions and fees $ — $ 68,244 $ 36 $ 68,279 Service charges and deposit account fees 11,680 37,984 50 49,714 Card-based and loan fees (a) 1,023 29,512 52 30,587 Trust and asset management fees — 40,946 — 40,946 Brokerage commissions and fees — 21,001 252 21,253 Other revenue (78 ) 7,349 221 7,491 Noninterest Income (in-scope of Topic 606) 12,625 205,036 611 218,270 Noninterest Income (out-of-scope of Topic 606) 26,531 19,073 7,646 53,252 Total Noninterest Income $ 39,156 $ 224,109 $ 8,257 $ 271,522 (a) Loan fees are out-of-scope of Topic 606. Nine Months Ended September 30, 2017 ($ in Thousands) Corporate and Community, Risk Management Consolidated Insurance commissions and fees $ — $ 62,286 $ 2 $ 62,288 Service charges and deposit account fees 12,334 36,259 61 48,654 Card-based and loan fees (a) 876 25,807 17 26,700 Trust and asset management fees — 37,066 — 37,066 Brokerage commissions and fees — 13,071 — 13,071 Other revenue 591 6,626 153 7,370 Noninterest Income (in-scope of Topic 606) 13,801 181,115 233 195,149 Noninterest Income (out-of-scope of Topic 606) 22,967 17,431 12,589 52,987 Total Noninterest Income $ 36,768 $ 198,546 $ 12,822 $ 248,136 (a) Loan fees are out-of-scope of Topic 606. Three Months Ended September 30, 2018 ($ in Thousands) Corporate and Commercial Specialty Community, Consumer, and Business Risk Management and Shared Services Consolidated Total Insurance commissions and fees $ — $ 21,632 $ 4 $ 21,636 Service charges and deposit account fees 3,669 13,210 25 16,904 Card-based and loan fees (a) 349 9,821 (15 ) 10,155 Trust and asset management fees — 14,140 — 14,140 Brokerage commissions and fees — 7,114 (30 ) 7,084 Other revenue 92 2,586 122 2,800 Noninterest Income (in-scope of Topic 606) 4,110 68,503 106 72,719 Noninterest Income (out-of-scope of Topic 606) 8,170 5,335 2,077 15,581 Total Noninterest Income $ 12,280 $ 73,838 $ 2,183 $ 88,300 (a) Loan fees are out-of-scope of Topic 606. Three Months Ended September 30, 2017 ($ in Thousands) Corporate and Community, Risk Management Consolidated Insurance commissions and fees $ — $ 19,813 $ 2 $ 19,815 Service charges and deposit account fees 3,824 12,432 12 16,268 Card-based and loan fees (a) 284 8,834 6 9,124 Trust and asset management fees — 12,784 — 12,785 Brokerage commissions and fees — 4,392 — 4,392 Other revenue 509 2,311 48 2,868 Noninterest Income (in-scope of Topic 606) 4,617 60,566 68 65,251 Noninterest Income (out-of-scope of Topic 606) 7,661 7,301 5,682 20,644 Total Noninterest Income $ 12,278 $ 67,867 $ 5,750 $ 85,895 (a) Loan fees are out-of-scope of Topic 606.
Revenue Recognition 606 [Text Block]	Below is a listing of performance obligations for the Corporation's main revenue streams. Revenue Stream Noninterest income in-scope of Topic 606 Insurance commissions and fees The Corporation's insurance revenue has two distinct performance obligations. The first performance obligation is the selling of the policy as an agent for the carrier. This performance obligation is satisfied upon binding of the policy. The second performance obligation is the ongoing servicing of the policy which is satisfied over the life of the policy. For employee benefits, the payment is typically received monthly. For property and casualty, payments can vary, but are typically received at, or in advance, of the policy period. Service charges and deposit account fees Service charges on deposit accounts consist of monthly service fees (i.e. business analysis fees and consumer service charges) and other deposit account related fees. The Corporation's performance obligation for monthly service fees is generally satisfied, and the related revenue recognized, over the period in which the service is provided. Other deposit account related fees are largely transactional based, and therefore, the Corporation's performance obligation is satisfied, and related revenue recognized, at a point in time. Payment for service charges on deposit accounts is primarily received immediately or in the following month through a direct charge to customers’ accounts. Card-based and loan fees (a) Card-based and loan fees are primarily comprised of debit and credit card income, ATM fees, and merchant services income. Debit and credit card income is primarily comprised of interchange fees earned whenever the Corporation's debit and credit cards are processed through card payment networks. ATM and merchant fees are largely transactional based, and therefore, the Corporation's performance obligation is satisfied, and related revenue recognized, at a point in time. Payment is typically received immediately or in the following month. Trust and asset management fees Trust and asset management income is primarily comprised of fees earned from the management and administration of trusts and other customer assets. The Corporation's performance obligation is generally satisfied over time and the resulting fees are recognized monthly, based upon the month-end market value of the assets under management and the applicable fee rate. Payment is generally received a few days after month end through a direct charge to customers’ accounts. The Corporation's performance obligation for these transactional-based services is generally satisfied, and related revenue recognized, at a point in time (i.e., as incurred). Payment is received shortly after services are rendered. Brokerage commissions and fees Brokerage commissions and fees primarily consists of investment advisory, brokerage, retirement services, and annuities. The Corporation's performance obligation for investment advisory services and retirement services is generally satisfied, and the related revenue recognized, over the period in which the services are provided. The performance obligation for annuities is satisfied upon sale of the annuity, and therefore, the related revenue is primarily recognized at the time of sale. Payment for these services are typically received immediately or in advance of the service. (a) Loan fees are out-of-scope of Topic 606. Arrangements with Multiple Performance Obligations The Corporation's contracts with customers may include multiple performance obligations. For such arrangements, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the expected cost plus margin. Practical Expedients We do not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less.

Acquisitions - Bank Mutual Acqu

Acquisitions - Bank Mutual Acquisition (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Feb. 01, 2018	Dec. 31, 2017	Sep. 30, 2017
Business Acquisition [Line Items]
Goodwill	$ 1,168,922		$ 976,239
Total liabilities	$ 2,340,294			$ 0
Purchase Accounting Adjustments
Business Acquisition [Line Items]
Cash and cash equivalents		$ 0
Investment securities		(6,238)
Federal Home Loan Bank stock, at cost		0
Loans		(48,043)
Premises and equipment, net		2,930
Bank owned life insurance		(24)
Goodwill
Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet)		58,100
Other real estate owned (included in other assets on the face of the Consolidated Balance Sheet)		199
Others assets		7,054
Deposits		2,498
Other borrowings		1,875
Other liabilities		4,487
February 1, 2018
Business Acquisition [Line Items]
Cash and cash equivalents		78,052
Investment securities		452,867
Federal Home Loan Bank stock, at cost		20,026
Loans		1,875,877
Premises and equipment, net		42,689
Bank owned life insurance		65,390
Goodwill		175,499
Core deposit intangibles (included in other intangible assets, net on the face of the Consolidated Balance Sheet)		58,100
Other real estate owned (included in other assets on the face of the Consolidated Balance Sheet)		4,848
Others assets		47,158
Total assets		2,820,506
Deposits		1,840,950
Other borrowings		431,886
Other liabilities		65,982
Total liabilities		2,338,818
Total consideration paid		$ 481,688

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ in Thousands	Feb. 01, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Approximate value of stock transaction					$ 488,408	$ 0
Bank Mutual
Business Acquisition [Line Items]
Number of shares received by shareholders (in shares)	0.422
Approximate number of shares issued	19,500,000
Approximate value of stock transaction	$ 482,000
Goodwill acquired	$ 175,000
Amortization period	10 years
Approximate additions to finite-lived intangible assets	$ 58,000
BKMU Goodwill Acquired Adjustments
Business Acquisition [Line Items]
Goodwill acquired		$ 2,000	$ 6,000
BKMU Assets Acquired Liabilities Assumed IncreaseDecrease
Business Acquisition [Line Items]
Updated appraisal information, fair value or premises and equipment		$ 2,000	6,000		$ 2,000
Updated appraisal and other adjustments, fair value of loans	less than $1 million
Anderson Insurance Investment Agency
Business Acquisition [Line Items]
Goodwill acquired			$ 7,000
Amortization period			7 years
Approximate value of acquisition			$ 10,000
Approximate additions to finite-lived intangible assets			$ 3,000
Diversified Insurance Solutions
Business Acquisition [Line Items]
Goodwill acquired				$ 10,000
Amortization period				10 years
Approximate value of acquisition				$ 19,000
Approximate additions to finite-lived intangible assets				$ 8,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies textuals (Details) - USD ($) shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expense Reclass (asu 2017-07)		$ 9,000
Visa Restricted Stock Owned	119
AOCI Attributable to Parent
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reporting Comprehensive Income(2018-02)	$ 13,654

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Calculations for basic and diluted earnings per common share
Net income	$ 85,929	$ 65,001	$ 244,578	$ 179,254
Preferred stock dividends	(2,409)	(2,339)	(7,077)	(7,008)
Net income available to common equity	83,521	62,662	237,501	172,246
Common shareholder dividends	(25,486)	(18,149)	(77,035)	(54,726)
Unvested share-based payment awards	(128)	(105)	(396)	(332)
Undistributed earnings	57,907	44,408	160,070	117,188
Undistributed earnings allocated to common shareholders	57,620	44,150	159,297	116,418
Undistributed earnings allocated to unvested share-based payment awards	288	258	772	770
Undistributed earnings	57,907	44,408	160,070	117,188
Basic
Distributed earnings to common shareholders	25,486	18,149	77,035	54,726
Undistributed earnings allocated to common shareholders	57,620	44,150	159,297	116,418
Total common shareholders earnings, basic	83,106	62,299	236,332	171,144
Diluted
Distributed earnings to common shareholders	25,486	18,149	77,035	54,726
Undistributed earnings allocated to common shareholders	57,620	44,150	159,297	116,418
Total common shareholders earnings, diluted	$ 83,106	$ 62,299	$ 236,332	$ 171,144
Weighted average common shares outstanding	170,516	150,565	168,249	150,983
Effect of dilutive common stock awards	2,188	1,815	2,101	2,081
Effect of dilutive common stock warrants	98	588	526	718
Diluted weighted average common shares outstanding	172,802	152,968	170,876	153,782
Basic earnings per common share	$ 0.49	$ 0.41	$ 1.40	$ 1.13
Diluted earnings per common share	$ 0.48	$ 0.41	$ 1.38	$ 1.11

Earnings Per Common Share (Text

Earnings Per Common Share (Textual) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Approximate anti-dilutive stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,400	1,000	1,400	1,000

Stock-Based Compensation, Stock

Stock-Based Compensation, Stock Option Activity (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair value assumptions of stock options
Dividend yield	2.50%	2.00%
Risk-free interest rate	2.60%	2.00%
Weighted average expected volatility	22.00%	25.00%
Weighted average expected life	5 years 9 months	5 years 6 months
Weighted average per share fair value of options	$ 4.47	$ 5.30
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock Options Shares Outstanding, Beginning balance (in shares)	5,118,687
Granted	938,740
Exercised	(966,213)
Forfeited or expired	(63,313)
Stock Options Shares Outstanding, Ending balance (in shares)	5,397,952		5,118,687
Options exercisable (in shares)	3,253,556
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)	$ 18.02
Granted, Weighted Average Exercise Price	$ 24.50
Assumed from Bank Mutual acquisition	$ 370,051
Exercised, Weighted Average Exercise Price	$ 16.57
Forfeited or expired, Weighted Average Exercise Price	25.17
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance (in usd per share)	$ 19.07		$ 18.02
Assumed from Bank Mutual acquisition, Weighted Average Exercise Price	$ 14.35
Options Exercisable, Weighted Average Exercise Price (in usd per share)	$ 16.89
Stock Options Outstanding, Weighted Average Remaining Contractual Term	6 years 5 months 23 days		6 years 5 months 23 days
Options exercisable, Weighted Average Remaining Contractual Term	5 years 2 months 26 days
Stock Options Outstanding, Aggregate Intrinsic Value	$ 37,423,000		$ 38,028,000
Options exercisable, Aggregate Intrinsic Value	$ 29,649,000

Stock-Based Compensation, Restr

Stock-Based Compensation, Restricted Stock Activity (Details)	9 Months Ended
	Sep. 30, 2018$ / sharesshares
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) | shares	2,026,071
Granted | shares	592,371
Vested | shares	(568,441)
Forfeited | shares	(50,478)
Outstanding Shares, Ending balance (in shares) | shares	1,999,523
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) | $ / shares	$ 19.68
Granted, Weighted Average Grant Date Fair Value | $ / shares	24.72
Vested, Weighted Average Grant Date Fair Value | $ / shares	18.33
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	22.25
Outstanding Weighted Average Grant Date Fair Value, Ending balance (in usd per share) | $ / shares	$ 21.94

Stock-Based Compensation (Detai

Stock-Based Compensation (Details Textuals) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Stock Based Compensation (Textuals) [Abstract]
Intrinsic value of stock options exercised	$ 10	$ 12
Total fair value of vested stock options	$ 4	$ 4
Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	150.00%
Service-based Restricted Stock Award
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Performance-based Restricted Stock Award
Share-based Compensation Arrangement by Share-based Payment Award
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Recognized compensation expense for vesting of stock options	$ 3	$ 3
Recognized compensation expense for accelerated vesting of stock options	less than $1 million
Unvested share-based payment awards	$ 5
Remaining requisite service periods, extend through	first quarter 2022
Restricted Stock Award
Share-based Compensation Arrangement by Share-based Payment Award
Recognized compensation expense for vesting of stock options	$ 10	$ 14
Recognized compensation expense for accelerated vesting of restricted stock options	1
Unvested share-based payment awards	$ 21
Remaining requisite service periods, extend through	first quarter 2022

Investment Securities, AFS and

Investment Securities, AFS and HTM Securities Amortized Costs and Fair Values (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment securities available for sale:
Amortized Cost	$ 4,191,366	$ 4,100,417
Gross Unrealized Gains	4,424	10,996
Gross Unrealized Losses	(141,593)	(67,967)
Fair Value	4,054,197	4,043,446
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	2,661,755	2,282,853
Held-to-maturity, Gross Unrealized Gains	11,223	26,543
Held-to-maturity, Gross Unrealized Loss	(77,961)	(25,822)
Held-to-maturity, Fair Value	2,595,017	2,283,574
US Treasury Securities
Investment securities available for sale:
Amortized Cost	1,001	1,003
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(7)
Fair Value	997	996
Obligations of state and political subdivisions (municipal securities)
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	1,682,162	1,281,320
Held-to-maturity, Gross Unrealized Gains	1,216	13,899
Held-to-maturity, Gross Unrealized Loss	(33,332)	(3,177)
Held-to-maturity, Fair Value	1,650,046	1,292,042
Residential Related Securities | FNMA/FHLMC
Investment securities available for sale:
Amortized Cost	320,148	457,680
Gross Unrealized Gains	2,658	9,722
Gross Unrealized Losses	(6,132)	(2,634)
Fair Value	316,674	464,768
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	95,603	40,995
Held-to-maturity, Gross Unrealized Gains	162	398
Held-to-maturity, Gross Unrealized Loss	(3,266)	(489)
Held-to-maturity, Fair Value	92,499	40,904
Residential Related Securities | GNMA
Investment securities available for sale:
Amortized Cost	2,259,538	1,944,453
Gross Unrealized Gains	0	275
Gross Unrealized Losses	(79,528)	(31,378)
Fair Value	2,180,010	1,913,350
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	367,536	414,440
Held-to-maturity, Gross Unrealized Gains	1,753	2,700
Held-to-maturity, Gross Unrealized Loss	(15,337)	(6,400)
Held-to-maturity, Fair Value	353,952	410,740
Private-label
Investment securities available for sale:
Amortized Cost	1,022	1,067
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(8)
Fair Value	1,018	1,059
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	0
Held-to-maturity, Fair Value	0
GNMA Commercial Mortgage-Related Securities
Investment securities available for sale:
Amortized Cost	1,306,802	1,547,173
Gross Unrealized Gains	0	5
Gross Unrealized Losses	(55,824)	(33,901)
Fair Value	1,250,978	1,513,277
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	516,454	546,098
Held-to-maturity, Gross Unrealized Gains	8,092	9,546
Held-to-maturity, Gross Unrealized Loss	(26,026)	(15,756)
Held-to-maturity, Fair Value	498,520	539,888
FFELP asset backed securities
Investment securities available for sale:
Amortized Cost	298,282	144,322
Gross Unrealized Gains	1,766	867
Gross Unrealized Losses	(101)	(13)
Fair Value	299,947	145,176
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	0
Held-to-maturity, Fair Value	0
Other Debt securities
Investment securities available for sale:
Amortized Cost	3,000	3,200
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(12)
Fair Value	3,000	3,188
Other Equity Securities
Investment securities available for sale:
Amortized Cost	1,573	1,519
Gross Unrealized Gains	0	127
Gross Unrealized Losses	0	(14)
Fair Value	1,573	1,632
Debt Securities, Held-to-maturity
Held to Maturity, Amortized Cost	0
Held-to-maturity, Fair Value	0
Investment Securities Class
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items]
Securities Received as Collateral	$ 3,700,000	$ 3,100,000

Investment Securities, AFS an_2

Investment Securities, AFS and HTM Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Amortized Cost
Available for Sale, Due in one year or less	$ 2,001
Available for Sale, Due after one year through five years	2,000
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	4,001
Available for Sale, amortized cost	4,191,366	$ 4,100,417
Fair Value
Available for Sale, Due in one year or less	1,997
Available for Sale, Due after one year through five years	2,000
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	3,997
Investment securities available for sale, at fair value	$ 4,054,197	4,043,446
Available for Sale, Ratio of Fair Value to Amortized Cost	96.70%
Amortized Cost
Held to Maturity, Due in one year or less	$ 48,561
Held to Maturity, Due after one year through five years	188,337
Held to Maturity, Due after five years through ten years	385,908
Held to Maturity, Due after ten years	1,059,355
Held to Maturity, Total Debt Securities	1,682,162
Held to Maturity, Amortized Cost	2,661,755	2,282,853
Fair Value
Held to Maturity, Due in one year or less	48,871
Held to Maturity, Due after one year through five years	186,335
Held to Maturity, Due after five years through ten years	377,705
Held to Maturity, Due after ten years	1,037,135
Held to Maturity, Securities, Debt Securities	1,650,046
Held to Maturity, Total debt securities at fair value	$ 2,595,017	2,283,574
Held to Maturity, Ratio of Fair Value to Amortized Cost	97.50%
Private-label
Amortized Cost
Available for Sale, amortized cost	$ 1,022	1,067
Fair Value
Investment securities available for sale, at fair value	1,018	1,059
Amortized Cost
Held to Maturity, Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities at fair value	0
GNMA Commercial Mortgage-Related Securities
Amortized Cost
Available for Sale, amortized cost	1,306,802	1,547,173
Fair Value
Investment securities available for sale, at fair value	1,250,978	1,513,277
Amortized Cost
Held to Maturity, Amortized Cost	516,454	546,098
Fair Value
Held to Maturity, Total debt securities at fair value	498,520	539,888
FFELP asset backed securities
Amortized Cost
Available for Sale, amortized cost	298,282	144,322
Fair Value
Investment securities available for sale, at fair value	299,947	145,176
Amortized Cost
Held to Maturity, Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities at fair value	0
Equity Securities
Amortized Cost
Available for Sale, amortized cost	1,573	1,519
Fair Value
Investment securities available for sale, at fair value	1,573	1,632
Amortized Cost
Held to Maturity, Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities at fair value	0
FNMA/FHLMC | Residential Related Securities
Amortized Cost
Available for Sale, amortized cost	320,148	457,680
Fair Value
Investment securities available for sale, at fair value	316,674	464,768
Amortized Cost
Held to Maturity, Amortized Cost	95,603	40,995
Fair Value
Held to Maturity, Total debt securities at fair value	92,499	40,904
GNMA | Residential Related Securities
Amortized Cost
Available for Sale, amortized cost	2,259,538	1,944,453
Fair Value
Investment securities available for sale, at fair value	2,180,010	1,913,350
Amortized Cost
Held to Maturity, Amortized Cost	367,536	414,440
Fair Value
Held to Maturity, Total debt securities at fair value	$ 353,952	$ 410,740

Investment Securities Gain_Loss

Investment Securities Gain/Loss Sale of Securities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Gross gains on available for sale securities	$ 1,954	$ 0
Gross gains on held to maturity securities	0	364
Total gains	1,954	364
Gross losses on available for sale securities	(3,938)	0
Gross losses on held to maturity securities	0	(5)
Total losses	(3,938)	(5)
Investment securities gains (losses), net	(1,985)	359
Proceeds from sales of investment securities	$ 601,130	$ 16,059

Investment Securities, AFS an_3

Investment Securities, AFS and HTM Securities Gross Unrealized Losses (Details) $ in Thousands	Sep. 30, 2018USD ($)security	Dec. 31, 2017USD ($)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	$ (32,768)	$ (15,099)
Unrealized losses on available for sale securities, 12 months or more	(108,825)	(52,868)
Total unrealized losses on available for sale securities	(141,593)	(67,967)
Fair value of unrealized losses on available for sale securities, less than 12 months	1,342,269	1,593,503
Fair value of unrealized losses on available for sale securities, 12 months or more	2,391,452	1,906,992
Total fair value of unrealized losses on available for sale securities	$ 3,733,721	$ 3,500,495
Available for sale, number of securities, less than 12 months | security	75	92
Available for sale, number of securities, 12 months or more | security	152	105
Held-to-maturity Securities Continuous Unrealized Loss Position
Unrealized losses on held to maturity securities, less than 12 months	$ (27,976)	$ (4,491)
Unrealized losses on held to maturity securities, 12 months or more	(49,983)	(21,331)
Total unrealized losses on held to maturity securities	$ (77,961)	$ (25,822)
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, 12 Months or Longer | security	316	183
Fair value of unrealized losses on held to maturity securities, less than 12 months	$ 1,209,055	$ 457,289
Fair value of unrealized losses on held to maturity securities, 12 months or more	946,637	751,088
Total fair value of unrealized losses on held to maturity securities	$ 2,155,692	$ 1,208,377
Held-to-maturity, Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions, less than 12 Months | security	1,350	202
US Treasury Securities
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	$ (7)
Unrealized losses on available for sale securities, 12 months or more	(4)	0
Total unrealized losses on available for sale securities	(4)	(7)
Fair value of unrealized losses on available for sale securities, less than 12 months	0	996
Fair value of unrealized losses on available for sale securities, 12 months or more	997	0
Total fair value of unrealized losses on available for sale securities	$ 997	$ 996
Available for sale, number of securities, less than 12 months | security	0	1
Available for sale, number of securities, 12 months or more | security	1	0
Obligations of state and political subdivisions (municipal securities)
Held-to-maturity Securities Continuous Unrealized Loss Position
Unrealized losses on held to maturity securities, less than 12 months	$ (22,552)	$ (746)
Unrealized losses on held to maturity securities, 12 months or more	(10,779)	(2,431)
Total unrealized losses on held to maturity securities	(33,332)	(3,177)
Fair value of unrealized losses on held to maturity securities, less than 12 months	1,026,504	122,761
Fair value of unrealized losses on held to maturity securities, 12 months or more	187,493	127,043
Total fair value of unrealized losses on held to maturity securities	$ 1,213,997	$ 249,804
Obligations of state and political subdivisions (municipal securities) | Held to maturity, number of securities, less than 12 months
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	1,288	157
Obligations of state and political subdivisions (municipal securities) | Held to maturity, number of securities, 12 months or more
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	228	132
Private-label
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	$ 0
Unrealized losses on available for sale securities, 12 months or more	(4)	(8)
Total unrealized losses on available for sale securities	(4)	(8)
Fair value of unrealized losses on available for sale securities, less than 12 months	0	0
Fair value of unrealized losses on available for sale securities, 12 months or more	1,018	1,059
Total fair value of unrealized losses on available for sale securities	$ 1,018	$ 1,059
Available for sale, number of securities, less than 12 months | security	0	0
Available for sale, number of securities, 12 months or more | security	1	1
GNMA Commercial Mortgage-Related Securities
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	$ (2,397)	$ (5,554)
Unrealized losses on available for sale securities, 12 months or more	(53,427)	(28,347)
Total unrealized losses on available for sale securities	(55,824)	(33,901)
Fair value of unrealized losses on available for sale securities, less than 12 months	63,846	480,514
Fair value of unrealized losses on available for sale securities, 12 months or more	1,187,406	1,026,642
Total fair value of unrealized losses on available for sale securities	$ 1,251,252	$ 1,507,156
Available for sale, number of securities, less than 12 months | security	4	33
Available for sale, number of securities, 12 months or more | security	89	70
Held-to-maturity Securities Continuous Unrealized Loss Position
Unrealized losses on held to maturity securities, less than 12 months	$ (951)	$ (299)
Unrealized losses on held to maturity securities, 12 months or more	(25,074)	(15,457)
Total unrealized losses on held to maturity securities	(26,026)	(15,756)
Fair value of unrealized losses on held to maturity securities, less than 12 months	28,308	52,997
Fair value of unrealized losses on held to maturity securities, 12 months or more	470,212	486,891
Total fair value of unrealized losses on held to maturity securities	$ 498,520	$ 539,888
GNMA Commercial Mortgage-Related Securities | Held to maturity, number of securities, less than 12 months
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	1	2
GNMA Commercial Mortgage-Related Securities | Held to maturity, number of securities, 12 months or more
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	24	23
FFELP asset backed securities
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	$ (101)	$ (13)
Unrealized losses on available for sale securities, 12 months or more	0	0
Total unrealized losses on available for sale securities	(101)	(13)
Fair value of unrealized losses on available for sale securities, less than 12 months	67,798	12,158
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	$ 67,798	$ 12,158
Available for sale, number of securities, less than 12 months | security	6	1
Available for sale, number of securities, 12 months or more | security	0	0
Other Debt securities
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		$ (12)
Unrealized losses on available for sale securities, 12 months or more		0
Total unrealized losses on available for sale securities		(12)
Fair value of unrealized losses on available for sale securities, less than 12 months		188
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		$ 188
Available for sale, number of securities, less than 12 months | security		1
Available for sale, number of securities, 12 months or more | security		0
Other Equity Securities
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		$ (14)
Unrealized losses on available for sale securities, 12 months or more		0
Total unrealized losses on available for sale securities		(14)
Fair value of unrealized losses on available for sale securities, less than 12 months		1,487
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		$ 1,487
Available for sale, number of securities, less than 12 months | security		3
Available for sale, number of securities, 12 months or more | security		0
FNMA/FHLMC | Residential Related Securities
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	$ (583)	$ (572)
Unrealized losses on available for sale securities, 12 months or more	(5,549)	(2,062)
Total unrealized losses on available for sale securities	(6,132)	(2,634)
Fair value of unrealized losses on available for sale securities, less than 12 months	60,527	69,939
Fair value of unrealized losses on available for sale securities, 12 months or more	172,119	142,093
Total fair value of unrealized losses on available for sale securities	$ 232,646	$ 212,032
Available for sale, number of securities, less than 12 months | security	18	9
Available for sale, number of securities, 12 months or more | security	14	9
Held-to-maturity Securities Continuous Unrealized Loss Position
Unrealized losses on held to maturity securities, less than 12 months	$ (1,798)	$ (73)
Unrealized losses on held to maturity securities, 12 months or more	(1,469)	(417)
Total unrealized losses on held to maturity securities	(3,266)	(490)
Fair value of unrealized losses on held to maturity securities, less than 12 months	64,876	13,143
Fair value of unrealized losses on held to maturity securities, 12 months or more	25,980	16,262
Total fair value of unrealized losses on held to maturity securities	$ 90,856	$ 29,405
FNMA/FHLMC | Residential Related Securities | Held to maturity, number of securities, less than 12 months
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	22	8
FNMA/FHLMC | Residential Related Securities | Held to maturity, number of securities, 12 months or more
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	18	10
GNMA | Residential Related Securities
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	$ (29,687)	$ (8,927)
Unrealized losses on available for sale securities, 12 months or more	(49,841)	(22,451)
Total unrealized losses on available for sale securities	(79,528)	(31,378)
Fair value of unrealized losses on available for sale securities, less than 12 months	1,150,098	1,028,221
Fair value of unrealized losses on available for sale securities, 12 months or more	1,029,912	737,198
Total fair value of unrealized losses on available for sale securities	$ 2,180,010	$ 1,765,419
Available for sale, number of securities, less than 12 months | security	47	44
Available for sale, number of securities, 12 months or more | security	47	25
Held-to-maturity Securities Continuous Unrealized Loss Position
Unrealized losses on held to maturity securities, less than 12 months	$ (2,676)	$ (3,373)
Unrealized losses on held to maturity securities, 12 months or more	(12,662)	(3,026)
Total unrealized losses on held to maturity securities	(15,337)	(6,399)
Fair value of unrealized losses on held to maturity securities, less than 12 months	89,367	268,388
Fair value of unrealized losses on held to maturity securities, 12 months or more	262,952	120,892
Total fair value of unrealized losses on held to maturity securities	$ 352,319	$ 389,280
GNMA | Residential Related Securities | Held to maturity, number of securities, less than 12 months
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	39	35
GNMA | Residential Related Securities | Held to maturity, number of securities, 12 months or more
Held-to-maturity Securities Continuous Unrealized Loss Position
Number of held to maturity securities in a continuous unrealized loss position | security	46	18

Investment Securities (Details

Investment Securities (Details Textual) - USD ($) $ in Thousands	Feb. 01, 2018	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Investment Securities (Textuals) [Abstract]
Proceeds from Sale of Available-for-sale Securities		$ 108,000		$ 601,130	$ 0
Debt Securities, Held-to-maturity, Sold, Amount					$ 16,000
Federal Home Loan Bank Stock		144,000		144,000		$ 89,000
Federal Reserve Bank Stock		77,000		77,000		76,000
Bank Mutual
Business Acquisition [Line Items]
Debt Securities, Available-for-sale, Sold at Par Value	$ 453,000
Investment Securities (Textuals) [Abstract]
Debt Securities, Available-for-sale, Sold at Par Value	$ 453,000
Investment Securities Class
Investment Securities (Textuals) [Abstract]
Securities Received as Collateral		$ 3,700,000		$ 3,700,000		$ 3,100,000
Securities Sold
Business Acquisition [Line Items]
Taxable Equivalent Yield		3.08%
Reinvestment
Business Acquisition [Line Items]
Taxable Equivalent Yield		3.51%
GNMA Commercial Mortgage-Related Securities
Business Acquisition [Line Items]
Debt Securities, Available-for-sale, Sold at Par Value			$ 40,000
Investment Securities (Textuals) [Abstract]
Debt Securities, Available-for-sale, Sold at Par Value			$ 40,000

Loans Composition (Details)

Loans Composition (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Total loans	$ 22,867,112	$ 20,784,991
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans	7,159,941	6,399,693
Commercial real estate — owner occupied
Loans and Leases Receivable Disclosure [Line Items]
Total loans	867,682	802,209
Commercial and business lending
Loans and Leases Receivable Disclosure [Line Items]
Total loans	8,027,622	7,201,902
Commercial real estate — investor
Loans and Leases Receivable Disclosure [Line Items]
Total loans	3,924,499	3,315,254
Real estate construction
Loans and Leases Receivable Disclosure [Line Items]
Total loans	1,416,209	1,451,684
Commercial real estate lending
Loans and Leases Receivable Disclosure [Line Items]
Total loans	5,340,708	4,766,938
Total commercial
Loans and Leases Receivable Disclosure [Line Items]
Total loans	13,368,330	11,968,840
Residential mortgage
Loans and Leases Receivable Disclosure [Line Items]
Total loans	8,227,649	7,546,534
Home equity
Loans and Leases Receivable Disclosure [Line Items]
Total loans	901,275	883,804
Other consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans	369,858	385,813
Total consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans	9,498,782	$ 8,816,151
Bank Mutual
Loans and Leases Receivable Disclosure [Line Items]
Purchased credit-impaired loans	$ 13,000

Loans Credit Quality Indicator

Loans Credit Quality Indicator (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 22,867,112	$ 20,784,991
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	22,313,389	20,171,876
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	163,182	227,692
Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	236,449	176,877
Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	154,092	208,546
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans	7,159,941	6,399,693
Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	6,886,363	6,015,884
Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	78,964	157,245
Commercial and industrial | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	144,468	113,778
Commercial and industrial | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	50,146	112,786
Commercial real estate — owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans	867,682	802,209
Commercial real estate — owner occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	823,615	723,291
Commercial real estate — owner occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	6,762	14,181
Commercial real estate — owner occupied | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	32,526	41,997
Commercial real estate — owner occupied | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	4,779	22,740
Commercial and business lending
Financing Receivable, Recorded Investment [Line Items]
Loans	8,027,622	7,201,902
Commercial and business lending | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	7,709,978	6,739,175
Commercial and business lending | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	85,725	171,426
Commercial and business lending | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	176,994	155,775
Commercial and business lending | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	54,925	135,526
Commercial real estate — investor
Financing Receivable, Recorded Investment [Line Items]
Loans	3,924,499	3,315,254
Commercial real estate — investor | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,790,423	3,266,389
Commercial real estate — investor | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	64,509	24,845
Commercial real estate — investor | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	49,842	19,291
Commercial real estate — investor | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	19,725	4,729
Real estate construction
Financing Receivable, Recorded Investment [Line Items]
Loans	1,416,209	1,451,684
Real estate construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,401,585	1,421,504
Real estate construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	10,078	29,206
Real estate construction | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	3,392	0
Real estate construction | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	1,154	974
Commercial real estate lending
Financing Receivable, Recorded Investment [Line Items]
Loans	5,340,708	4,766,938
Commercial real estate lending | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	5,192,008	4,687,893
Commercial real estate lending | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	74,587	54,051
Commercial real estate lending | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	53,234	19,291
Commercial real estate lending | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	20,879	5,703
Total commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	13,368,330	11,968,840
Total commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	12,901,986	11,427,068
Total commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	160,312	225,477
Total commercial | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	230,228	175,066
Total commercial | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	75,804	141,229
Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	8,227,649	7,546,534
Residential mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	8,154,521	7,490,860
Residential mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	1,159	426
Residential mortgage | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	6,073	1,616
Residential mortgage | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	65,896	53,632
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	901,275	883,804
Home equity | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	887,690	868,958
Home equity | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	1,113	1,137
Home equity | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	148	195
Home equity | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	12,324	13,514
Other consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	369,858	385,813
Other consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	369,192	384,990
Other consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	598	652
Other consumer | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Other consumer | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	68	171
Total consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	9,498,782	8,816,151
Total consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	9,411,403	8,744,808
Total consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	2,870	2,215
Total consumer | Potential Problem
Financing Receivable, Recorded Investment [Line Items]
Loans	6,221	1,811
Total consumer | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 78,288	$ 67,317

Loans Past Due Status (Details)

Loans Past Due Status (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Summarized details of Loans
Current	$ 22,679,140,000	$ 20,555,250,000
Nonaccrual	154,092,000	208,546,000
Total loans	22,867,112,000	20,784,991,000
Nonaccrual Loans, Current Portion	$ 92,000,000	$ 135,000,000
Percent of current nonaccrual loans	60.00%	65.00%
30-59 Days Past Due
Summarized details of Loans
Total Past Due	$ 28,138,000	$ 16,861,000
60-89 Days Past Due
Summarized details of Loans
Total Past Due	3,568,000	2,467,000
90 Days or More Past Due
Summarized details of Loans
Total Past Due	2,175,000	1,867,000
Commercial and industrial
Summarized details of Loans
Current	7,103,744,000	6,286,369,000
Nonaccrual	50,146,000	112,786,000
Total loans	7,159,941,000	6,399,693,000
Commercial and industrial | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	5,592,000	170,000
Commercial and industrial | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	140,000	101,000
Commercial and industrial | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	319,000	267,000
Commercial real estate — owner occupied
Summarized details of Loans
Current	856,777,000	779,421,000
Nonaccrual	4,779,000	22,740,000
Total loans	867,682,000	802,209,000
Commercial real estate — owner occupied | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	5,589,000	48,000
Commercial real estate — owner occupied | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	537,000	0
Commercial real estate — owner occupied | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	0	0
Commercial and business lending
Summarized details of Loans
Current	7,960,521,000	7,065,790,000
Nonaccrual	54,925,000	135,526,000
Total loans	8,027,622,000	7,201,902,000
Commercial and business lending | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	11,181,000	218,000
Commercial and business lending | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	677,000	101,000
Commercial and business lending | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	319,000	267,000
Commercial real estate — investor
Summarized details of Loans
Current	3,904,401,000	3,310,000,000
Nonaccrual	19,725,000	4,729,000
Total loans	3,924,499,000	3,315,254,000
Commercial real estate — investor | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	373,000	374,000
Commercial real estate — investor | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	0	0
Commercial real estate — investor | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	0	151,000
Real estate construction
Summarized details of Loans
Current	1,414,538,000	1,450,459,000
Nonaccrual	1,154,000	974,000
Total loans	1,416,209,000	1,451,684,000
Real estate construction | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	517,000	168,000
Real estate construction | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	0	83,000
Real estate construction | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	0	0
Commercial real estate lending
Summarized details of Loans
Current	5,318,939,000	4,760,459,000
Nonaccrual	20,879,000	5,703,000
Total loans	5,340,708,000	4,766,938,000
Commercial real estate lending | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	890,000	542,000
Commercial real estate lending | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	0	83,000
Commercial real estate lending | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	0	151,000
Total commercial
Summarized details of Loans
Current	13,279,460,000	11,826,249,000
Nonaccrual	75,804,000	141,229,000
Total loans	13,368,330,000	11,968,840,000
Total commercial | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	12,071,000	760,000
Total commercial | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	677,000	184,000
Total commercial | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	319,000	418,000
Residential mortgage
Summarized details of Loans
Current	8,152,854,000	7,483,350,000
Nonaccrual	65,896,000	53,632,000
Total loans	8,227,649,000	7,546,534,000
Residential mortgage | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	7,829,000	9,186,000
Residential mortgage | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	1,070,000	366,000
Residential mortgage | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	0	0
Home equity
Summarized details of Loans
Current	880,871,000	863,465,000
Nonaccrual	12,324,000	13,514,000
Total loans	901,275,000	883,804,000
Home equity | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	6,989,000	5,688,000
Home equity | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	1,091,000	1,137,000
Home equity | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	0	0
Other consumer
Summarized details of Loans
Current	365,955,000	382,186,000
Nonaccrual	68,000	171,000
Total loans	369,858,000	385,813,000
Other consumer | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	1,249,000	1,227,000
Other consumer | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	730,000	780,000
Other consumer | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	1,856,000	1,449,000
Total consumer
Summarized details of Loans
Current	9,399,680,000	8,729,001,000
Nonaccrual	78,288,000	67,317,000
Total loans	9,498,782,000	8,816,151,000
Total consumer | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	16,067,000	16,101,000
Total consumer | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	2,891,000	2,283,000
Total consumer | 90 Days or More Past Due
Summarized details of Loans
Total Past Due	$ 1,856,000	$ 1,449,000

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	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	$ 168,568	$ 247,575
Unpaid Principal Balance	202,895	275,814
Related Allowance	15,781	25,846
Average Recorded Investment	202,574	236,860
Interest Income Recognized	$ 3,774	$ 8,051
Net Recorded Investment of the Impaired Loans	75.00%	80.00%
Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	$ 115,865	$ 175,681
Unpaid Principal Balance	131,384	181,002
Related Allowance	15,781	25,846
Average Recorded Investment	153,802	140,098
Interest Income Recognized	3,053	7,254
Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	52,703	71,894
Unpaid Principal Balance	71,511	94,812
Related Allowance	0	0
Average Recorded Investment	48,772	96,762
Interest Income Recognized	721	797
Commercial and industrial
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	86,246	142,244
Unpaid Principal Balance	110,509	166,418
Related Allowance	6,013	10,838
Average Recorded Investment	102,294	147,769
Interest Income Recognized	773	3,121
Commercial and industrial | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	57,935	81,649
Unpaid Principal Balance	68,894	83,579
Related Allowance	6,013	10,838
Average Recorded Investment	70,339	58,494
Interest Income Recognized	1,121	2,629
Commercial and industrial | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	28,311	60,595
Unpaid Principal Balance	41,615	82,839
Related Allowance	0	0
Average Recorded Investment	31,955	89,275
Interest Income Recognized	348	492
Commercial real estate — owner occupied
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	7,518	26,234
Unpaid Principal Balance	8,575	26,766
Related Allowance	20	2,973
Average Recorded Investment	19,503	14,072
Interest Income Recognized	143	772
Commercial real estate — owner occupied | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	3,746	23,796
Unpaid Principal Balance	3,752	23,937
Related Allowance	20	2,973
Average Recorded Investment	15,460	12,124
Interest Income Recognized	143	736
Commercial real estate — owner occupied | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	3,772	2,438
Unpaid Principal Balance	4,823	2,829
Related Allowance	0	0
Average Recorded Investment	4,043	1,948
Interest Income Recognized	0	36
Commercial and business lending
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	93,764	168,478
Unpaid Principal Balance	119,084	193,184
Related Allowance	6,033	13,811
Average Recorded Investment	121,797	161,841
Interest Income Recognized	916	3,893
Commercial and business lending | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	61,681	105,445
Unpaid Principal Balance	72,646	107,516
Related Allowance	6,033	13,811
Average Recorded Investment	85,799	70,618
Interest Income Recognized	1,264	3,365
Commercial and business lending | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	32,083	63,033
Unpaid Principal Balance	46,438	85,668
Related Allowance	0	0
Average Recorded Investment	35,998	91,223
Interest Income Recognized	348	528
Commercial real estate — investor
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	11,986	19,118
Unpaid Principal Balance	16,378	19,157
Related Allowance	287	1,597
Average Recorded Investment	15,922	16,924
Interest Income Recognized	905	1,739
Commercial real estate — investor | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	2,069	17,823
Unpaid Principal Balance	2,148	17,862
Related Allowance	287	1,597
Average Recorded Investment	14,929	16,924
Interest Income Recognized	13	1,694
Commercial real estate — investor | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,917	1,295
Unpaid Principal Balance	14,230	1,295
Related Allowance	0	0
Average Recorded Investment	993	0
Interest Income Recognized	892	45
Real estate construction
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	440	467
Unpaid Principal Balance	516	578
Related Allowance	74	86
Average Recorded Investment	451	484
Interest Income Recognized	22	29
Real estate construction | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	440	467
Unpaid Principal Balance	516	578
Related Allowance	74	86
Average Recorded Investment	451	484
Interest Income Recognized	22	29
Real estate construction | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
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
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	12,426	19,585
Unpaid Principal Balance	16,894	19,735
Related Allowance	361	1,683
Average Recorded Investment	16,373	17,408
Interest Income Recognized	927	1,768
Commercial real estate lending | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	2,509	18,290
Unpaid Principal Balance	2,664	18,440
Related Allowance	361	1,683
Average Recorded Investment	15,380	17,408
Interest Income Recognized	35	1,723
Commercial real estate lending | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,917	1,295
Unpaid Principal Balance	14,230	1,295
Related Allowance	0	0
Average Recorded Investment	993	0
Interest Income Recognized	892	45
Total commercial
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	106,190	188,063
Unpaid Principal Balance	135,978	212,919
Related Allowance	6,394	15,494
Average Recorded Investment	138,170	179,249
Interest Income Recognized	1,843	5,661
Total commercial | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	64,190	123,735
Unpaid Principal Balance	75,310	125,956
Related Allowance	6,394	15,494
Average Recorded Investment	101,179	88,026
Interest Income Recognized	1,299	5,088
Total commercial | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	42,000	64,328
Unpaid Principal Balance	60,668	86,963
Related Allowance	0	0
Average Recorded Investment	36,991	91,223
Interest Income Recognized	544	573
Residential mortgage
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	50,722	47,486
Unpaid Principal Balance	54,244	50,126
Related Allowance	5,937	6,512
Average Recorded Investment	52,093	45,410
Interest Income Recognized	1,493	1,831
Residential mortgage | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	40,797	40,561
Unpaid Principal Balance	44,197	42,922
Related Allowance	5,937	6,512
Average Recorded Investment	41,589	40,411
Interest Income Recognized	1,321	1,614
Residential mortgage | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,925	6,925
Unpaid Principal Balance	10,047	7,204
Related Allowance	0	0
Average Recorded Investment	10,504	4,999
Interest Income Recognized	172	217
Home equity
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	10,470	10,891
Unpaid Principal Balance	11,485	11,631
Related Allowance	3,327	3,718
Average Recorded Investment	11,123	11,061
Interest Income Recognized	436	556
Home equity | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,692	10,250
Unpaid Principal Balance	10,689	10,986
Related Allowance	3,327	3,718
Average Recorded Investment	9,846	10,521
Interest Income Recognized	431	549
Home equity | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	778	641
Unpaid Principal Balance	796	645
Related Allowance	0	0
Average Recorded Investment	1,277	540
Interest Income Recognized	5	7
Other consumer
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	1,186	1,135
Unpaid Principal Balance	1,188	1,138
Related Allowance	123	122
Average Recorded Investment	1,188	1,140
Interest Income Recognized	2	3
Other consumer | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	1,186	1,135
Unpaid Principal Balance	1,188	1,138
Related Allowance	123	122
Average Recorded Investment	1,188	1,140
Interest Income Recognized	2	3
Other consumer | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Total consumer
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	62,378	59,512
Unpaid Principal Balance	66,917	62,895
Related Allowance	9,387	10,352
Average Recorded Investment	64,404	57,611
Interest Income Recognized	1,931	2,390
Total consumer | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	51,675	51,946
Unpaid Principal Balance	56,074	55,046
Related Allowance	9,387	10,352
Average Recorded Investment	52,623	52,072
Interest Income Recognized	1,754	2,166
Total consumer | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	10,703	7,566
Unpaid Principal Balance	10,843	7,849
Related Allowance	0	0
Average Recorded Investment	11,781	5,539
Interest Income Recognized	177	$ 224
Bank Mutual
Loan and Lease Receivables, Impaired [Abstract]
Purchased credit-impaired loans	$ 13,000

Loans, Troubled Debt Restructur

Loans, Troubled Debt Restructurings Performing and Nonaccrual (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	$ 69,154	$ 74,618
Nonaccrual Restructured Loans	33,757	23,486
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	38,885	30,047
Nonaccrual Restructured Loans	142	1,776
Commercial real estate — owner occupied
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	3,746	3,989
Nonaccrual Restructured Loans	0	0
Commercial real estate — investor
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	350	14,389
Nonaccrual Restructured Loans	9,917	0
Real estate construction
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	218	310
Nonaccrual Restructured Loans	222	157
Residential mortgage
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	16,986	17,068
Nonaccrual Restructured Loans	20,952	18,991
Home equity
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	7,792	7,705
Nonaccrual Restructured Loans	2,515	2,537
Other consumer
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	1,177	1,110
Nonaccrual Restructured Loans	$ 9	$ 25

Loans, Loans Modified in a Trou

Loans, Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	71	104
Recorded Investment	$ 10,138	$ 17,476
Unpaid Principal Balance	$ 10,353	$ 22,428
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	6	19
Recorded Investment	$ 1,954	$ 11,387
Unpaid Principal Balance	$ 1,995	$ 15,898
Commercial real estate — owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	2
Recorded Investment	$ 0	$ 710
Unpaid Principal Balance	$ 0	$ 710
Commercial real estate — investor
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	1	0
Recorded Investment	$ 958	$ 0
Unpaid Principal Balance	$ 1,022	$ 0
Residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	29	48
Recorded Investment	$ 5,655	$ 4,445
Unpaid Principal Balance	$ 5,733	$ 4,638
Home equity
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	32	35
Recorded Investment	$ 1,552	$ 934
Unpaid Principal Balance	$ 1,582	$ 1,182
Other consumer
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	0
Recorded Investment	$ 19	$ 0
Unpaid Principal Balance	$ 21	$ 0

Loans, Troubled Debt Restruct_2

Loans, Troubled Debt Restructurings Subsequent Default (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)loan	Sep. 30, 2017USD ($)loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	43	36
Recorded Investment | $	$ 4,178	$ 1,707
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	3	1
Recorded Investment | $	$ 0	$ 1
Residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	12	21
Recorded Investment | $	$ 2,579	$ 1,335
Home equity
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	28	14
Recorded Investment | $	$ 1,599	$ 371

Loans, Changes in the Allowance

Loans, Changes in the Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2018	Dec. 31, 2017
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	$ 265,880	$ 278,335
Charge offs	(44,385)	(56,246)
Recoveries	14,255	16,791
Net Charge offs	(30,130)	(39,455)
Provision for loan losses	500	27,000
Balance at end of period	236,250	265,880
Allowance for loan losses:
Individually evaluated			$ 15,781	$ 25,846
Collectively evaluated			220,469	240,034
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	265,880	265,880	236,250	265,880
Loans:
Individually evaluated			168,568	247,575
Collectively evaluated			22,685,411	20,537,416
Acquired and accounted for under ASC 310-30			13,133
Total loans			22,867,112	20,784,991
Commercial and industrial
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	123,068	140,126
Charge offs	(29,707)	(44,533)
Recoveries	9,609	11,465
Net Charge offs	(20,098)	(33,068)
Provision for loan losses	2,643	16,010
Balance at end of period	105,613	123,068
Allowance for loan losses:
Individually evaluated			6,013	10,838
Collectively evaluated			99,600	112,230
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	105,613	140,126	105,613	123,068
Loans:
Individually evaluated			86,246	142,244
Collectively evaluated			7,071,043	6,257,449
Acquired and accounted for under ASC 310-30			2,652
Total loans			7,159,941	6,399,693
Commercial real estate — owner occupied
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	10,352	14,034
Charge offs	(1,361)	(344)
Recoveries	354	173
Net Charge offs	(1,007)	(171)
Provision for loan losses	105	(3,511)
Balance at end of period	9,451	10,352
Allowance for loan losses:
Individually evaluated			20	2,973
Collectively evaluated			9,431	7,379
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	9,451	14,034	9,451	10,352
Loans:
Individually evaluated			7,518	26,234
Collectively evaluated			858,747	775,975
Acquired and accounted for under ASC 310-30			1,416
Total loans			867,682	802,209
Commercial real estate — investor
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	41,059	45,285
Charge offs	(5,278)	(991)
Recoveries	139	242
Net Charge offs	(5,139)	(749)
Provision for loan losses	5,737	(3,477)
Balance at end of period	41,657	41,059
Allowance for loan losses:
Individually evaluated			287	1,597
Collectively evaluated			41,370	39,462
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	41,059	41,059	41,657	41,059
Loans:
Individually evaluated			11,986	19,118
Collectively evaluated			3,904,266	3,296,136
Acquired and accounted for under ASC 310-30			8,247
Total loans			3,924,499	3,315,254
Real estate construction
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	34,370	26,932
Charge offs	(298)	(604)
Recoveries	340	74
Net Charge offs	42	(530)
Provision for loan losses	(7,676)	7,968
Balance at end of period	26,737	34,370
Allowance for loan losses:
Individually evaluated			74	86
Collectively evaluated			26,663	34,284
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	34,370	34,370	26,737	34,370
Loans:
Individually evaluated			440	467
Collectively evaluated			1,415,745	1,451,217
Acquired and accounted for under ASC 310-30			24
Total loans			1,416,209	1,451,684
Residential mortgage
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	29,607	27,046
Charge offs	(1,310)	(2,611)
Recoveries	1,049	927
Net Charge offs	(261)	(1,684)
Provision for loan losses	(1,884)	4,245
Balance at end of period	27,461	29,607
Allowance for loan losses:
Individually evaluated			5,937	6,512
Collectively evaluated			21,524	23,095
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	27,461	27,046	27,461	29,607
Loans:
Individually evaluated			50,722	47,486
Collectively evaluated			8,176,217	7,499,048
Acquired and accounted for under ASC 310-30			710
Total loans			8,227,649	7,546,534
Home equity
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	22,126	20,364
Charge offs	(2,508)	(2,724)
Recoveries	2,171	3,194
Net Charge offs	(337)	470
Provision for loan losses	(2,101)	1,292
Balance at end of period	19,687	22,126
Allowance for loan losses:
Individually evaluated			3,327	3,718
Collectively evaluated			16,360	18,408
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	22,126	22,126	19,687	22,126
Loans:
Individually evaluated			10,470	10,891
Collectively evaluated			890,721	872,913
Acquired and accounted for under ASC 310-30			84
Total loans			901,275	883,804
Other consumer
Changes in the allowance for loan losses by portfolio segment
Balance at beginning of period	5,298	4,548
Charge offs	(3,923)	(4,439)
Recoveries	593	716
Net Charge offs	(3,330)	(3,723)
Provision for loan losses	3,676	4,473
Balance at end of period	5,644	5,298
Allowance for loan losses:
Individually evaluated			123	122
Collectively evaluated			5,521	5,176
Acquired and accounted for under ASC 310-30			0
Total allowance for loan losses	$ 5,298	$ 5,298	5,644	5,298
Loans:
Individually evaluated			1,186	1,135
Collectively evaluated			368,672	384,678
Acquired and accounted for under ASC 310-30			0
Total loans			$ 369,858	$ 385,813

Loans Changes in the Allowance

Loans Changes in the Allowance for Loan Losses by Oil and Gas Segment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 265,880	$ 278,335
Charge offs	(44,385)	(56,246)
Recoveries	14,255	16,791
Net Charge offs	(30,130)	(39,455)
Provision for loan losses	500	27,000
Balance at end of period	236,250	265,880
Allowance for loan losses
Individually evaluated			$ 15,781	$ 25,846
Collectively evaluated			220,469	240,034
Total allowance for loan losses	265,880	265,880	236,250	265,880
Loans
Individually evaluated			168,568	247,575
Collectively evaluated			22,685,411	20,537,416
Total loans			22,867,112	20,784,991
Oil and Gas Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	27,000	38,000
Charge offs	(24,000)	(25,000)
Recoveries	3,000	0
Net Charge offs	(20,000)	(25,000)
Provision for loan losses	3,000	14,000
Balance at end of period	10,000	27,000
Allowance for loan losses
Individually evaluated			0	5,000
Collectively evaluated			10,000	22,000
Total allowance for loan losses	$ 10,000	$ 38,000	10,000	27,000
Loans
Individually evaluated			32,000	77,000
Collectively evaluated			700,000	523,000
Total loans			$ 731,000	$ 600,000

Loans, Changes in the Allowan_2

Loans, Changes in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Change in the allowance for unfunded commitments
Balance at beginning of period	$ 24,000
Balance at end of period	25,000	$ 24,000
Allowance for Unfunded Commitments:
Change in the allowance for unfunded commitments
Balance at beginning of period	24,400	25,400
Provision for unfunded commitments	(1,500)	(1,000)
Amount recorded at acquisition	2,436	0
Balance at end of period	$ 25,336	$ 24,400

Loans Changes to Accretable Yie

Loans Changes to Accretable Yield (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 0	$ 0
Purchases	4,853	0
Accretion	(310)	0
Net reclassification from non-accretable yield	144	0
Other	(5)	0
Balance at end of period	$ 4,681	$ 0

Loans Narrative (Details)

Loans Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Recorded Investment, loans modified in troubled debt restructuring	$ 10,138	$ 17,476
Restructured Loans Subsequently Accruing	4,000
Ytd Restructured Loans Still On Nonaccrual	6,000
Net unaccreted purchase discount	27,000
Unaccreted purchase discount, performing loans	21,000
Unaccreted purchase discount, nonperforming loans	6,000
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	236,250		$ 265,880	$ 278,335
Oil and Gas Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses	$ 10,000		$ 27,000	$ 38,000
Percent of loans	1.40%
Bank Mutual
Financing Receivable, Allowance for Credit Losses [Line Items]
Purchased credit-impaired loans	$ 13,000

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets, Summary of Core Deposit and Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Summary of core deposit intangibles and other intangibles
Amortization of other intangible assets	$ 2,233	$ 450	$ 5,926	$ 1,459
Core Deposit Intangibles
Summary of core deposit intangibles and other intangibles
Gross carrying amount	58,100		58,100		$ 4,385
Accumulated amortization	(3,873)		(3,873)		(4,385)
Net Book Value	54,227		54,227		0
Amortization of other intangible assets			3,873		112
Adjustments to Core Deposits [Member]
Summary of core deposit intangibles and other intangibles
Additions during the period			58,100		0
Other Intangible Assets
Summary of core deposit intangibles and other intangibles
Gross carrying amount	44,931		44,931		34,572
Finite-Lived Intangible Assets, Period Increase (Decrease)			(43)		0
Accumulated amortization	(21,045)		(21,045)		(18,992)
Net Book Value	$ 23,843		23,843		15,580
Additions during the period			10,359		2,162
Amortization of other intangible assets			$ 2,053		$ 1,847

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets, Mortgage Servicing Rights Roll-Forward (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Mortgage servicing rights:
Mortgage servicing rights at beginning of period		$ 59,168	$ 62,085
MSR Addition from Business Combination		8,136	0
Additions		7,826	7,167
Amortization		(7,143)	(10,084)
Mortgage servicing rights at end of period		67,987	59,168
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Valuation allowance at beginning of period		(784)	(609)
(Additions) recoveries, net		669	(175)
Valuation allowance at end of period		(115)	(784)
Mortgage servicing rights, net		67,872	58,384
Fair value of mortgage servicing rights		87,120	64,387
Portfolio of residential mortgage loans serviced for others (“servicing portfolio”)		$ 8,547,230	$ 7,646,846
Mortgage servicing rights, net to servicing portfolio		0.79%	0.76%
Mortgage servicing rights expense	[1]	$ 6,474	$ 10,259
[1]	(a) 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.

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets, Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Core Deposit Intangibles
Estimated future amortization expense
Three Months Ending December 31, 2018	$ 1,453
Year ending December 31, 2019	5,810
Year ending December 31, 2020	5,810
Year ending December 31, 2021	5,810
Year ending December 31, 2022	5,810
Year ending December 31, 2023	5,810
Beyond 2,023	23,724
Net Book Value	54,227	$ 0
Other Intangible Assets
Estimated future amortization expense
Three Months Ending December 31, 2018	780
Year ending December 31, 2019	2,824
Year ending December 31, 2020	2,707
Year ending December 31, 2021	2,682
Year ending December 31, 2022	2,659
Year ending December 31, 2023	2,640
Beyond 2,023	9,551
Net Book Value	23,843	$ 15,580
Mortgage Servicing Rights
Estimated future amortization expense
Three Months Ending December 31, 2018	2,362
Year ending December 31, 2019	9,029
Year ending December 31, 2020	7,892
Year ending December 31, 2021	6,873
Year ending December 31, 2022	5,995
Year ending December 31, 2023	5,246
Beyond 2,023	30,590
Net Book Value	$ 67,987

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets (Details Textuals) - USD ($)	Feb. 01, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill				$ 1,168,922,000		$ 976,239,000
Goodwill, Impairment Loss				$ 0	$ 0
Bank Mutual
Business Acquisition [Line Items]
Goodwill acquired	$ 175,000,000
Approximate additions to finite-lived intangible assets	$ 58,000,000
Diversified Insurance Solutions
Business Acquisition [Line Items]
Goodwill acquired			$ 10,000,000
Approximate additions to finite-lived intangible assets			$ 8,000,000
Anderson Insurance Investment Agency
Business Acquisition [Line Items]
Goodwill acquired		$ 7,000,000
Approximate additions to finite-lived intangible assets		$ 3,000,000

Short and Long-Term Funding (Co

Short and Long-Term Funding (Components of Short-term and Long-term Funding) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Short-term Funding [Abstract]
Federal funds purchased	$ 25,890	$ 141,950
Securities sold under agreements to repurchase	140,666	182,865
Federal funds purchased and securities sold under agreements to repurchase	166,556	324,815
Commercial paper	43,604	67,467
Total short-term funding	210,159	392,282
Long-term Funding
Senior notes, at par	550,000	250,000
Subordinated notes, at par	250,000	250,000
Other long-term funding and capitalized costs	(4,785)	(2,718)
Total long-term funding	795,215	497,282
TotalShortTermLongTermExcludingFHLB	1,005,375	889,564
Advances from Federal Home Loan Banks [Abstract]
ShortTermFHLBAdvances	405,000	284,000
LongTermFHLBAdvances	2,927,655	2,900,168
TotalFHLB_Advances	3,332,655	3,184,168
Total short and long-term funding, excluding FHLB advances	$ 4,338,030	$ 4,073,732

Short and Long-Term Funding (Re

Short and Long-Term Funding (Remaining Contractual Maturity of the Securities Sold Under Agreements to Repurchase) (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	$ 140,666,000	$ 182,865,000
Overnight and Continuous
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	140,666,000	182,865,000
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
Agency mortgage-related securities
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	140,666,000	182,865,000
Agency mortgage-related securities | Overnight and Continuous
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	140,666,000	182,865,000
Agency mortgage-related securities | Up to 30 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
Agency mortgage-related securities | 30-90 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	0	0
Agency mortgage-related securities | Greater than 90 days
RemainingContractualMaturityoftheSecuritiesSoldUnderAgreementtoRepurchase [Line Items]
Repurchase agreements	$ 0	$ 0

Short and Long-Term Funding FHL

Short and Long-Term Funding FHLB Maturity Schedule (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
FHLB_Maturity_ [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 3,332,655	$ 3,184,168
FHLB Weighted Average Coupon Rate	2.10%	1.26%
FHLB Maturity within One Year [Domain]
FHLB_Maturity_ [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 1,371,059	$ 2,434,000
FHLB Weighted Average Coupon Rate	1.76%	1.26%
FHLB Maturity One Year to Two Years [Domain]
FHLB_Maturity_ [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 1,662,019	$ 750,013
FHLB Weighted Average Coupon Rate	2.29%	1.23%
FHLB Maturity Over Two Years to Three Years [Domain]
FHLB_Maturity_ [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 216,289	$ 155
FHLB Weighted Average Coupon Rate	2.53%	4.91%
FHLB Maturity Over Three Years [Domain]
FHLB_Maturity_ [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 83,289	$ 0
FHLB Weighted Average Coupon Rate	2.62%	0.00%

Short and Long-Term Funding (Lo

Short and Long-Term Funding (Long-term Funding Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended
	Nov. 30, 2014	Sep. 30, 2018	Aug. 31, 2018	Dec. 31, 2017
Subordinated Borrowing [Line Items]
Carrying Value of Securities Purchased under Agreements to Resell and Deposits Paid for Securities Borrowed		$ 237,000
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances		3,332,655		$ 3,184,168
Two Thousand Eighteen Senior Notes [Member] [Domain]
Subordinated Borrowing [Line Items]
New Senior Debt Issued			$ 300,000
Debt Instrument, Interest Rate, Stated Percentage			3.50%
Two Thousand Fourteen Senior Notes
Subordinated Borrowing [Line Items]
New Senior Debt Issued	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	2.75%
Two Thousand Fourteen Subordinated Notes
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures Issued	$ 250,000
Debt Instrument, Term	10 years
Subordinated Borrowing, Interest Rate	4.25%
FHLB Maturity within One Year [Domain]
Subordinated Borrowing [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances		1,371,059		$ 2,434,000
FLHB Advances, Putable [Domain]
Subordinated Borrowing [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances		2,600,000
FHLB, Increase in Advances [Domain]
Subordinated Borrowing [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances		$ 148,000

Derivative and Hedging Activi_3

Derivative and Hedging Activities, Derivative Instruments Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Not Designated as Hedging Instrument | Trading assets | Interest rate-related instruments — customer and mirror
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	$ 2,712,813	$ 2,183,687
Derivative, Fair Value, Net	68,916	28,494
Not Designated as Hedging Instrument | Trading assets | Foreign currency exchange forwards
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	124,137	124,851
Derivative, Fair Value, Net	1,974	2,495
Not Designated as Hedging Instrument | Trading assets | Commodity contracts
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	401,849	457,868
Derivative, Fair Value, Net	69,439	38,686
Not Designated as Hedging Instrument | Trading liabilities | Interest rate-related instruments — customer and mirror
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	2,712,813	2,183,687
Derivative, Fair Value, Net	(68,103)	(28,035)
Not Designated as Hedging Instrument | Trading liabilities | Foreign currency exchange forwards
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	119,748	118,094
Derivative, Fair Value, Net	(1,840)	(2,339)
Not Designated as Hedging Instrument | Trading liabilities | Commodity contracts
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	401,968	457,108
Derivative, Fair Value, Net	(68,997)	(37,286)
Not Designated as Hedging Instrument | Other assets | Interest rate lock commitments (mortgage)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	259,762	222,736
Derivative, Fair Value, Net	1,685	1,538
Not Designated as Hedging Instrument | Other assets | Forward commitments (mortgage)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	271,561
Derivative, Fair Value, Net	1,352
Not Designated as Hedging Instrument | Other assets | Purchased options (time deposit)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	21,269	31,063
Derivative, Fair Value, Net	577	1,175
Not Designated as Hedging Instrument | Other liabilities | Forward commitments (mortgage)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount		164,567
Derivative, Fair Value, Net		(313)
Not Designated as Hedging Instrument | Other liabilities | Written options (time deposit)
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	21,269	31,063
Derivative, Fair Value, Net	(577)	(1,175)
Designated as Hedging Instrument | Other assets | interest rate product [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Notional Amount	500,000	0
Derivative, Fair Value, Net	$ 4,902	$ 0

Derivative and Hedging Activi_4

Derivative and Hedging Activities - Cumulative Basis Adjustment for Fair Value Hedges (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Balance Sheet Recording of Fair Value Hedge [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	$ 140,328	$ 69,675
Designated as Hedging Instrument
Balance Sheet Recording of Fair Value Hedge [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	500,000
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	5,000
Amortized cost basis of hedged asset	1,100,000
adjustment [Member] | Designated as Hedging Instrument
Balance Sheet Recording of Fair Value Hedge [Line Items]
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	(4,931)
Carrying Value [Member] | Designated as Hedging Instrument
Balance Sheet Recording of Fair Value Hedge [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	$ 495,069

Derivative and Hedging Activi_5

Derivative and Hedging Activities Income impact of Fair Value and Cash Flow Hedge (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Interest Income [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ (30)	$ 0
Other Operating Income (Expense) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Income [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(4,931)	0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Other Operating Income (Expense) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	0	0
Designated as Hedging Instrument | Interest Income [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	4,902	0
Designated as Hedging Instrument | Other Operating Income (Expense) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ 0	$ 0

Derivative and Hedging Activi_6

Derivative and Hedging Activities Derivative Impact on Perfomance (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Capital Market Fees [Member] | Interest Rate Related Instruments Customer and Mirror [Member]
Derivative Impact on Performance [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 354	$ (115)
Capital Market Fees [Member] | Foreign Exchange Forward [Member]
Derivative Impact on Performance [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(22)	(39)
Capital Market Fees [Member] | Commodity Contract [Member]
Derivative Impact on Performance [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(958)	476
Mortgage Banking [Member] | Interest Rate Lock Commitments [Member]
Derivative Impact on Performance [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	147	2,523
Mortgage Banking [Member] | Forward Contracts [Member]
Derivative Impact on Performance [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 1,665	$ (2,674)

Derivative and Hedging Activi_7

Derivative and Hedging Activities (Details Textuals) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Investment securities and cash equivalents pledged as collateral	$ 33	$ 24
Derivative collateral right to reclaim cash	$ 37	$ 22

Balance Sheet Offsetting (Detai

Balance Sheet Offsetting (Details) - September 30, 2018 - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 78,124	$ 29,503
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	78,124	29,503
Financial instruments	(26,385)	(16,140)
Collateral	(50,134)	(13,234)
Net amount	1,605	129
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	64,591	37,164
Gross amounts offset in the balance sheet	0	0
Net amounts presented in the balance sheet	64,591	37,164
Financial instruments	(26,385)	(16,140)
Collateral	(37,480)	(20,662)
Net amount	$ 726	$ 362

Commitments, Off-Balance Shee_3

Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters, Summary of Lending Related and Other Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of lending-related and other commitments [Line Items]
Lending related commitments, fair value	$ 0	$ 0
Summary of lending-related and other commitments
Loans Repurchased Under Make Whole Requests	1,000
Commitments to extend credit, excluding commitments to originate residential mortgage loans held for sale
Summary of lending-related and other commitments
Lending related commitments	8,471,141	8,027,187
Commercial Letters Of Credit
Summary of lending-related and other commitments
Lending related commitments	9,122	11,886
Standby Letters of Credit
Summary of lending-related and other commitments
Lending related commitments	260,092	235,361
Standby letters of credit, fair value	$ 3,000	$ 2,000

Commitments, Off-Balance Shee_4

Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters Residential Mortgage Repurchase Reserve (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Residential mortgage repurchase reserve
Balance at beginning of period	$ 24,000
Balance at end of period	25,000	$ 24,000
Mortgage Repurchase Reserve
Residential mortgage repurchase reserve
Balance at beginning of period	987	900
Repurchase provision expense	254	246
Charge offs, net	(125)	(159)
Amount recorded at acquisition	88	0
Balance at end of period	$ 1,204	$ 987

Commitments, Off-Balance Shee_5

Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters (Details Textuals) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 25	$ 24
Loans Repurchased Under Make Whole Requests	$ 1
Loans Sold To Outside Investors Loss ReimbursementSettlement Paid	zero	negligible
Loans Sold To Outside Investors Original Amount	$ 10,800
Loans Sold To Outside Investors Remaining Outstanding Amount	7,000
Residential Mortgage Loans Sold With Recourse Risk	46	$ 44
Residential Mortgage Loans Sold With Credit Recourse Risk	60	73
UnconsolidatedProjectsLowIncomeHousing [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Other Investments	132	147
Commitments Under Unconsolidated Projects	85	119
PrincipalInvestmentCommitment [Member]
Commitments, Off-Balance Sheet Arrangements, and Contingent Liabilities (Textuals) [Line Items]
Other Investments	$ 25	$ 23

Fair Value Measurements, Assets

Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment securities available for sale:
Investment securities available for sale	$ 4,054,197	$ 4,043,446
Trading assets	140,328	69,675
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	138,940	67,660
Fair Value, Inputs, Level 1
Investment securities available for sale:
Investment securities available for sale	2,570	2,628
Fair Value, Inputs, Level 2
Investment securities available for sale:
Investment securities available for sale	4,051,627	4,040,818
Trading assets	145,808	70,850
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	139,517	68,835
Fair Value, Inputs, Level 3
Investment securities available for sale:
Trading assets	3,037	1,538
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	0	313
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | US Treasury Securities
Investment securities available for sale:
Investment securities available for sale	997	996
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Other Debt And Other Equity Securities
Investment securities available for sale:
Investment securities available for sale	1,573	1,632
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Total investment securities available for sale
Investment securities available for sale:
Investment securities available for sale	2,570	2,628
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | FNMA / FHLMC
Investment securities available for sale:
Investment securities available for sale	316,674	464,768
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | GNMA
Investment securities available for sale:
Investment securities available for sale	2,180,010	1,913,350
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Private-label
Investment securities available for sale:
Investment securities available for sale	1,018	1,059
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | GNMA Commercial Mortgage-Related Securities
Investment securities available for sale:
Investment securities available for sale	1,250,978	1,513,277
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | FFELP asset backed securities
Investment securities available for sale:
Investment securities available for sale	299,947	145,176
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Other Debt And Other Equity Securities
Investment securities available for sale:
Investment securities available for sale	3,000	3,188
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Total investment securities available for sale
Investment securities available for sale:
Investment securities available for sale	4,051,627	4,040,818
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Residential Loans Held For Sale Member
Investment securities available for sale:
Trading assets	134,361	85,544
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Interest rate-related instruments — customer and mirror
Investment securities available for sale:
Trading assets	68,916	28,494
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	68,103	28,035
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Foreign currency exchange forwards
Investment securities available for sale:
Trading assets	1,974	2,495
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	1,840	2,339
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Commodity contracts
Investment securities available for sale:
Trading assets	69,439	38,686
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	68,997	37,286
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Purchased options (time deposit)
Investment securities available for sale:
Trading assets	577	1,175
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	577	1,175
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Interest rate lock commitments (mortgage)
Investment securities available for sale:
Trading assets	1,685	1,538
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Forward commitments (mortgage)
Investment securities available for sale:
Trading assets	1,352	0
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	0	313
Total commercial | Fair Value, Inputs, Level 2
Investment securities available for sale:
Loans Held-for-sale, Fair Value Disclosure	30,452	0
Designated as Hedging Instrument
Investment securities available for sale:
Trading assets	500,000
Designated as Hedging Instrument | Fair Value, Inputs, Level 2
Investment securities available for sale:
Interest Rate Fair Value Hedge Derivative at Fair Value, Net	$ 4,902	$ 0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments Classified Within Level 3 (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Mar. 31, 2017
Total investment securities available for sale
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Beginning Balance	$ 0	$ 200
Ending Balance	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Mortgage derivative loss	0	0
Total investment securities available for sale | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfer of level 3 to level 2 based on new pricing information		200
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Transfer out of level 3 securities		(200)
Derivative Financial Instruments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	1,225	3,114
Mortgage derivative loss	1,816	(1,889)
Ending Balance	$ 3,041	1,225
Derivative Financial Instruments | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfer of level 3 to level 2 based on new pricing information		0
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Transfer out of level 3 securities		$ 0
Investment security
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfer of level 3 to level 2 based on new pricing information			$ 200
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Transfer out of level 3 securities			$ (200)

Fair Value Measurements, Asse_2

Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Commercial Loans Held-for-sale, Fair Value Disclosure	$ 30,452		$ 0
Mortgage servicing rights	67,872		58,384
Mortgage Servicing Rights (MSR) Impairment (Recovery)	(669)	$ 286
Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Commercial Loans Held-for-sale, Fair Value Disclosure	30,452		0
Residential Held-for-sale, Fair Value Disclosure	134,361		85,544
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Other Real Estate Owned Fair Value Disclosure	2,688		2,604
Foreclosure / OREO expense, net	(965)		(939)
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Impaired loans	39,438		92,534
Provision for Credit Losses, Impaired Loans	(13,183)		(32,159)
Mortgage servicing rights	87,120		64,387
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ 669		$ (175)

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Unobservable Level 3 Measurements (Details) - Fair Value, Inputs, Level 3	9 Months Ended
	Sep. 30, 2018
Discounted Cash Flow | Servicing Contracts
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	11.00%
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Prepayment Speed	8.00%
Appraisals/Discounted Cash Flow | Impaired Finance Receivable
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate	34.00%

Fair Value Measurements, Fair V

Fair Value Measurements, Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financial assets
Cash and due from banks	$ 374,168	$ 483,666
Interest-bearing deposits in other financial institutions	147,848	199,702
Federal funds sold and securities purchased under agreements to resell	24,325	32,650
Debt Securities, Held-to-maturity	2,661,755	2,282,853
Investment securities held to maturity, fair value	2,595,017	2,283,574
Investment securities available for sale	4,054,197	4,043,446
FHLB and Federal Reserve Bank stocks	220,825	165,331
Commercial Loans Held-for-sale, Fair Value Disclosure	30,452	0
Loans, net	22,630,861	20,519,111
Bank and Corporate Owned Life Insurance	661,009	591,057
Derivatives (trading and other assets)	140,328	69,675
Financial liabilities
Short-term funding	210,159	392,282
Other long-term funding	795,215	497,282
Derivatives (trading and other liabilities)	138,940	67,660
Letters of Credit Outstanding, Amount	260,000	235,000
Fair Value, Inputs, Level 1
Financial assets
Cash and due from banks	374,168	483,666
Cash and due from banks, Fair Value	374,168	483,666
Interest-bearing deposits in other financial institutions	147,848	199,702
Interest-bearing deposits in other financial institutions, fair value	147,848	199,702
Federal funds sold and securities purchased under agreements to resell	24,325	32,650
Federal funds sold and securities purchased under agreements to resell, fair value	24,325	32,650
Investment securities available for sale	2,570	2,628
Investment securities available for sale, fair value	2,570	2,628
Fair Value, Inputs, Level 2
Financial assets
Debt Securities, Held-to-maturity	2,661,755	2,282,853
Investment securities held to maturity, fair value	2,595,017	2,283,574
Investment securities available for sale	4,051,627	4,040,818
Investment securities available for sale, fair value	4,051,627	4,040,818
FHLB and Federal Reserve Bank stocks	220,825	165,331
FHLB and Federal Reserve Bank stocks, fair value	220,825	165,331
Residential Held-for-sale, Carrying Amount	134,361	85,544
Residential Held-for-sale, Fair Value Disclosure	134,361	85,544
Commercial loans held for sale	30,452	0
Commercial Loans Held-for-sale, Fair Value Disclosure	30,452	0
Bank and Corporate Owned Life Insurance	661,009	591,057
Bank owned life insurance, fair value	661,009	591,057
Derivatives (trading and other assets)	145,808	70,850
Derivatives (trading and other assets), fair value	145,808	70,850
Financial liabilities
Brokered CDs and other time deposits	3,288,752	2,349,069
Brokered CDs and other time deposits, fair value	3,288,752	2,349,069
Short-term funding	615,159	676,282
Short-term funding, fair value	615,159	676,282
Other long-term funding	3,722,870	3,397,450
Long-term funding, fair value	3,719,147	3,411,368
Standby letters of credit	2,600	2,402
Standby letters of credit, fair value	2,600	2,402
Derivatives (trading and other liabilities)	139,517	68,835
Derivatives (trading and other liabilities), fair value	139,517	68,835
Fair Value, Inputs, Level 3
Financial assets
Loans, net	22,630,861	20,519,111
Loans, net, fair value	22,140,169	20,314,984
Derivatives (trading and other assets)	3,037	1,538
Derivatives (trading and other assets), fair value	3,037	1,538
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts	21,542,860	20,436,893
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, fair value	21,542,860	20,436,893
Derivatives (trading and other liabilities)	0	313
Derivatives (trading and other liabilities), fair value	$ 0	$ 313

Fair Value Measurements (Detail

Fair Value Measurements (Details Textuals)	9 Months Ended
	Sep. 30, 2018
Fair Value of Assets and Liabilities [Line Items]
Closing ratio	86.00%

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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
RAP
Net period benefit cost for the pension and postretirement plans
Service cost	$ 1,885	$ 1,713	$ 5,670	$ 5,276
Interest cost	1,682	1,795	5,002	5,307
Expected return on plan assets	(4,777)	(4,929)	(14,287)	(14,692)
Amortization of prior service cost	(18)	(19)	(56)	(56)
Amortization of actuarial loss	549	619	1,474	1,594
Total net pension and periodic benefit cost	(680)	(821)	(2,197)	(2,571)
Bank Mutual Pension Plan
Net period benefit cost for the pension and postretirement plans
Interest cost	654		1,737
Expected return on plan assets	(1,220)		(2,812)
Total net pension and periodic benefit cost	(566)		(1,075)
Postretirement Plan(b)
Net period benefit cost for the pension and postretirement plans
Interest cost	27	26	80	74
Amortization of prior service cost	(19)	(19)	(56)	(57)
Amortization of actuarial loss	2	2	6	2
Total net pension and periodic benefit cost	$ 11	$ 9	$ 30	$ 19

Retirement Plans (Details Textu

Retirement Plans (Details Textuals) (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2018	Jun. 30, 2018
Bank Mutual Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 6,000	$ 31,000
RAP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 4,000

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Income Statement Data Abstract
Net interest income	$ 219,392	$ 190,122	$ 655,625	$ 554,215
Net intersegment interest income (expense)	0	0	0	0
Segment net interest income	219,392	190,122	655,625	554,215
Noninterest income	88,300	85,895	271,522	248,136
Total revenue	307,692	276,017	927,146	802,351
Credit provision	(5,000)	5,000	(1,000)	26,000
Noninterest Expense	204,413	177,427	628,636	527,434
Income (loss) before income taxes	108,279	93,590	299,510	248,917
Income tax expense (benefit)	22,349	28,589	54,932	69,663
Net income	$ 85,929	$ 65,001	$ 244,578	$ 179,254
Return on average allocated capital (ROCET1)	13.20%	11.70%	12.90%	11.00%
Segment Balance Sheet Data
Average earning assets	$ 30,474,870	$ 27,459,795	$ 30,060,938	$ 26,851,992
Average loans	22,973,717	20,899,137	22,689,170	20,500,978
Average deposits	24,695,918	22,441,445	24,001,604	21,813,679
Average allocated capital (CET1)	2,513,272	2,119,675	2,464,354	2,093,962
Allocated Goodwill - Segment			1,168,922	972,006
Business Combination, Acquisition Related Costs		0		0
Operating Segments | Corporate and Commercial Specialty
Segment Income Statement Data Abstract
Net interest income	113,298	93,114	339,718	270,256
Net intersegment interest income (expense)	(13,018)	(758)	(36,151)	1,359
Segment net interest income	100,280	92,356	303,567	271,615
Noninterest income	12,280	12,278	39,156	36,768
Total revenue	112,560	104,634	342,723	308,383
Credit provision	11,232	9,499	32,955	32,549
Noninterest Expense	41,828	39,681	122,853	116,578
Income (loss) before income taxes	59,500	55,454	186,914	159,256
Income tax expense (benefit)	12,098	19,070	36,978	53,082
Net income	$ 47,402	$ 36,384	$ 149,937	$ 106,174
Return on average allocated capital (ROCET1)	15.50%	12.80%	16.60%	12.70%
Segment Balance Sheet Data
Average earning assets	$ 11,981,760	$ 10,923,762	$ 11,814,674	$ 10,846,418
Average loans	11,974,090	10,916,829	11,804,458	10,837,933
Average deposits	8,695,170	7,398,970	8,127,134	6,759,105
Average allocated capital (CET1)	1,215,331	1,125,181	1,207,925	1,121,800
Allocated Goodwill - Segment			524,525	428,000
Operating Segments | Community, Consumer, and Business
Segment Income Statement Data Abstract
Net interest income	91,323	81,058	268,137	236,407
Net intersegment interest income (expense)	21,951	9,894	63,301	33,603
Segment net interest income	113,275	90,952	331,438	270,011
Noninterest income	73,838	67,867	224,109	198,546
Total revenue	187,113	158,819	555,547	468,557
Credit provision	5,280	5,046	15,125	15,317
Noninterest Expense	139,653	120,241	405,338	361,580
Income (loss) before income taxes	42,180	33,532	135,084	91,660
Income tax expense (benefit)	8,861	11,736	28,371	32,081
Net income	$ 33,319	$ 21,796	$ 106,713	$ 59,579
Return on average allocated capital (ROCET1)	20.00%	14.70%	21.90%	13.60%
Segment Balance Sheet Data
Average earning assets	$ 10,456,159	$ 9,608,242	$ 10,333,412	$ 9,418,173
Average loans	10,453,485	9,602,098	10,329,888	9,414,880
Average deposits	13,716,862	11,788,606	13,518,903	11,568,220
Average allocated capital (CET1)	662,017	588,841	652,745	584,774
Allocated Goodwill - Segment			644,397	544,006
Operating Segments | Risk Management and Shared Services
Segment Income Statement Data Abstract
Net interest income	14,770	15,951	47,770	47,552
Net intersegment interest income (expense)	(8,933)	(9,136)	(27,150)	(34,963)
Segment net interest income	5,837	6,814	20,620	12,589
Noninterest income	2,183	5,750	8,257	12,822
Total revenue	8,019	12,564	28,876	25,411
Credit provision	(21,512)	(9,545)	(49,081)	(21,866)
Noninterest Expense	22,932	17,505	100,445	49,276
Income (loss) before income taxes	6,599	4,604	(22,488)	(1,999)
Income tax expense (benefit)	1,390	(2,217)	(10,416)	(15,500)
Net income	$ 5,209	$ 6,821	$ (12,072)	$ 13,501
Return on average allocated capital (ROCET1)	1.80%	4.40%	(4.20%)	2.20%
Segment Balance Sheet Data
Average earning assets	$ 8,036,951	$ 6,927,791	$ 7,912,853	$ 6,587,401
Average loans	546,142	380,210	554,824	248,165
Average deposits	2,283,886	3,253,869	2,355,566	3,486,354
Average allocated capital (CET1)	635,924	$ 405,653	603,684	$ 387,388
Business Combination, Acquisition Related Costs	$ 2,271		$ 29,983

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ (62,758)
Debt Securities, Available-for-sale, Realized Loss			3,938	$ 0
Personnel expense	$ 124,476	$ 108,098	366,141	321,946
Change in Equity Securities(2016-01)			84
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	52	(76)	684	2,499
Total other comprehensive income (loss)	15,631	818	72,762	(391)
Ending Balance	(135,520)		(135,520)
Investment Securities Available For Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(90,986)	(19,428)	(38,453)	(20,079)
Other comprehensive income (loss) before reclassifications	(21,345)	(1,986)	(82,099)	1,646
Debt Securities, Available-for-sale, Realized Loss	(30)		1,985
Personnel expense	0	0	0	0
Other Expenses	0	0	0	0
Change in Equity Securities(2016-01)			(84)
Reporting Comprehensive Income(2018-02)			(8,419)
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	(52)	76	(684)	(2,499)
Income tax (expense) benefit	5,456	734	20,796	328
Total other comprehensive income (loss)	(15,971)	(1,176)	68,505	525
Ending Balance	(106,958)	(20,604)	(106,958)	(20,604)
Defined Benefit Pension and Post Retirement Obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(28,902)	(34,042)	(24,305)	(34,600)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Debt Securities, Available-for-sale, Realized Loss			0
Personnel expense	(37)	(38)	(112)	(113)
Other Expenses	551	621	1,480	1,596
Change in Equity Securities(2016-01)			0
Reporting Comprehensive Income(2018-02)			(5,235)
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	0	0	0	0
Income tax (expense) benefit	(174)	(225)	(390)	(567)
Total other comprehensive income (loss)	340	358	4,257	(916)
Ending Balance	(28,562)	(33,684)	(28,562)	(33,684)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(119,888)	(53,470)	(62,758)	(54,679)
Other comprehensive income (loss) before reclassifications	(21,345)	(1,986)	(82,099)	1,646
Debt Securities, Available-for-sale, Realized Loss	(30)		1,985
Personnel expense	(37)	(38)	(112)	(113)
Other Expenses	551	621	1,480	1,596
Change in Equity Securities(2016-01)			(84)
Reporting Comprehensive Income(2018-02)			(13,654)
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	(52)	76	(684)	(2,499)
Income tax (expense) benefit	5,282	509	20,406	(239)
Total other comprehensive income (loss)	(15,631)	(818)	72,762	(391)
Ending Balance	$ (135,520)	$ (54,288)	$ (135,520)	$ (54,288)

Revenues (Details)

Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	$ 72,719	$ 65,251	$ 218,270	$ 195,149
Noninterest Income (out-of-scope of Topic 606)	15,581	20,644	53,252	52,987
Total noninterest income	88,300	85,895	271,522	248,136
Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	21,636	19,815	68,279	62,288
Deposit Account
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	16,904	16,268	49,714	48,654
Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	10,155	9,124	30,587	26,700
Fiduciary and Trust
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	14,140	12,785	40,946	37,066
Brokerage commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	7,084	4,392	21,253	13,071
Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	2,800	2,868	7,491	7,370
Corporate and Commercial Specialty
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	4,110	4,617	12,625	13,801
Noninterest Income (out-of-scope of Topic 606)	8,170	7,661	26,531	22,967
Corporate and Commercial Specialty | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0	0
Corporate and Commercial Specialty | Deposit Account
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	3,669	3,824	11,680	12,334
Corporate and Commercial Specialty | Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	349	284	1,023	876
Corporate and Commercial Specialty | Fiduciary and Trust
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0	0
Corporate and Commercial Specialty | Brokerage commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0	0
Corporate and Commercial Specialty | Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	92	509	(78)	591
Community, Consumer, and Business
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	68,503	60,566	205,036	181,115
Noninterest Income (out-of-scope of Topic 606)	5,335	7,301	19,073	17,431
Community, Consumer, and Business | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	21,632	19,813	68,244	62,286
Community, Consumer, and Business | Deposit Account
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	13,210	12,432	37,984	36,259
Community, Consumer, and Business | Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	9,821	8,834	29,512	25,807
Community, Consumer, and Business | Fiduciary and Trust
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	14,140	12,784	40,946	37,066
Community, Consumer, and Business | Brokerage commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	7,114	4,392	21,001	13,071
Community, Consumer, and Business | Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	2,586	2,311	7,349	6,626
Risk Management and Shared Services
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	106	68	611	233
Noninterest Income (out-of-scope of Topic 606)	2,077	5,682	7,646	12,589
Risk Management and Shared Services | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	4	2	36	2
Risk Management and Shared Services | Deposit Account
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	25	12	50	61
Risk Management and Shared Services | Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	(15)	6	52	17
Risk Management and Shared Services | Fiduciary and Trust
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0	0
Risk Management and Shared Services | Brokerage commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	(30)	0	252	0
Risk Management and Shared Services | Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	$ 122	$ 48	$ 221	$ 153