Commerce Bancshares (CBSH) 10-K 22 Feb 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 09, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Type	10-K
Amendment Flag	false
Document Fiscal Period Focus	FY
Entity Registrant Name	COMMERCE BANCSHARES INC /MO/
Entity Central Index Key	22,356
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		106,710,134
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 5,271,000,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Loans	$ 13,983,674	$ 13,412,736
Allowance for loan losses	(159,532)	(155,932)
Net loans	13,824,142	13,256,804
Loans Receivable Held-for-sale, Amount	21,398	14,456
Investment securities:
Available for sale Securities	8,774,280	9,649,203
Trading	18,269	22,225
Non-marketable	100,758	99,558
Total investment securities	8,893,307	9,770,986
Federal funds sold and short-term securities purchased under agreements to resell	42,775	15,470
Long-term securities purchased under agreements to resell	700,000	725,000
Interest-bearing deposits with banks	30,631	272,275
Cash and due from banks	438,439	494,690
Land, buildings and equipment – net	335,110	337,705
Goodwill	138,921	138,921
Other intangible assets – net	7,618	6,709
Other assets	401,074	608,408
Total assets	24,833,415	25,641,424
LIABILITIES AND STOCKHOLDERS’ EQUITY
Non-interest bearing	7,158,962	7,429,398
Savings, interest checking and money market	11,499,620	11,430,789
Time open and C.D.’s of less than $100,000	634,646	713,075
Time open and C.D.'s of $100,000 and over	1,132,218	1,527,833
Total deposits	20,425,446	21,101,095
Federal funds purchased and securities sold under agreements to repurchase	1,507,138	1,723,905
Other borrowings	1,758	102,049
Other liabilities	180,889	213,243
Total liabilities	22,115,231	23,140,292
Commerce Bancshares, Inc. stockholders’ equity:
Preferred stock, $1 par value	144,784	144,784
Common stock, $5 par value	535,407	510,015
Capital surplus	1,815,360	1,552,454
Retained earnings	221,374	292,849
Treasury stock, at cost	(14,473)	(15,294)
Accumulated other comprehensive income	14,108	10,975
Total Commerce Bancshares, Inc. stockholders’ equity	2,716,560	2,495,783
Non-controlling interest	1,624	5,349
Total equity	2,718,184	2,501,132
Total liabilities and equity	$ 24,833,415	$ 25,641,424

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans:
Mortgages Held-for-sale, Fair Value Disclosure	$ 15,327	$ 9,263
Investment Securities:
Available for sale securities, pledged	$ 662,515	$ 568,553
Stockholders' Equity:
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	6,000	6,000
Common stock, par value	$ 5	$ 5
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	107,081,397	102,003,046
Treasury stock, shares	276,968	364,711

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
INTEREST INCOME
Interest and fees on loans	$ 543,825	$ 489,956	$ 456,664
Interest on loans held for sale	1,000	1,317	191
Interest on investment securities	214,689	207,184	191,801
Interest on federal funds sold and short-term securities purchased under agreements to resell	230	78	60
Interest on long-term securities purchased under agreements to resell	15,440	13,544	13,172
Interest on deposits with banks	2,223	973	528
Total interest income	777,407	713,052	662,416
INTEREST EXPENSE
Savings, interest checking and money market	17,309	14,366	13,374
Time open and C.D.’s of less than $100,000	2,645	2,809	3,236
Time open and C.D.’s of $100,000 and over	10,859	8,545	6,051
Interest on federal funds purchased and securities sold under agreements to repurchase	9,829	3,315	1,861
Interest on other borrowings	3,086	3,968	3,574
Total interest expense	43,728	33,003	28,096
Net interest income	733,679	680,049	634,320
Provision for loan losses	45,244	36,318	28,727
Net interest income after provision for loan losses	688,435	643,731	605,593
NON-INTEREST INCOME
Bank card transaction fees	180,441	181,879	178,926
Trust fees	135,159	121,795	118,437
Deposit account charges and other fees	90,060	86,394	80,416
Noninterest Income, Other	7,996	10,655	11,476
Capital market fees	14,630	13,784	13,784
Loan fees and sales	13,948	11,412	8,228
Other	44,370	48,473	36,872
Total non-interest income	486,604	474,392	448,139
INVESTMENT SECURITIES GAINS (LOSSES), NET
Investment securities gains (losses), net	25,051	(53)	6,320
NON-INTEREST EXPENSE
Salaries and employee benefits	448,321	427,310	400,701
Net occupancy	45,612	46,290	44,788
Equipment	18,568	19,141	19,086
Supplies and communication	22,790	24,135	22,970
Data processing and software	92,246	92,722	83,944
Marketing	16,325	16,032	16,107
Deposit insurance	13,986	13,327	12,146
Community Service	34,377	3,906	3,180
Other	77,459	74,202	73,565
Total non-interest expense	769,684	717,065	676,487
Income before income taxes	430,406	401,005	383,565
Less income taxes	110,506	124,151	116,590
Net income	319,900	276,854	266,975
Less non-controlling interest expense	517	1,463	3,245
NET INCOME ATTRIBUTABLE TO COMMERCE BANCSHARES, INC.	319,383	275,391	263,730
Preferred stock dividends	9,000	9,000	9,000
Net Income (Loss) Available to Common Stockholders, Basic	$ 310,383	$ 266,391	$ 254,730
Net income per common share - basic (in dollars per share)	$ 2.90	$ 2.50	$ 2.33
Net income per common share - diluted (in dollars per share)	$ 2.89	$ 2.49	$ 2.32

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 319,900	$ 276,854	$ 266,975
Other comprehensive income (loss):
Net unrealized gains (losses) on securities for which a portion of an other-than-temporary impairment has been recorded in earnings	412	(341)	(518)
Net unrealized gains (losses) on other securities	3,022	(22,422)	(31,517)
Change in pension loss	(301)	1,268	2,412
Other comprehensive income (loss)	3,133	(21,495)	(29,623)
Comprehensive income	323,033	255,359	237,352
Non-controlling interest expense	517	1,463	3,245
Comprehensive income attributable to Commerce Bancshares, Inc.	$ 322,516	$ 253,896	$ 234,107

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES:
Net income	$ 319,900	$ 276,854	$ 266,975
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	45,244	36,318	28,727
Provision for depreciation and amortization	39,732	40,929	42,803
Amortization of investment security premiums, net	35,423	31,493	32,618
Deferred income tax (benefit) expense	13,617	(2,059)	7,432
Investment securities (gains) losses, net	(25,051)	53	(6,320)
Net gains on sales of loans held for sale	(8,008)	(5,850)	(3,076)
Proceeds from sales of loans held for sale	215,373	160,875	97,813
Origination Of Loans Held For Sale	(216,064)	(163,469)	(103,199)
Net (increase) decrease in trading securities	7,585	73,780	(86,045)
Stock-based compensation	12,105	11,525	10,147
(Increase) decrease in interest receivable	(4,459)	(3,642)	(4,992)
Decrease in interest payable	38	1,107	336
Increase (decrease) in income taxes payable	(27,685)	4,509	11,733
Donation of securities	32,036	0	0
Other changes, net	(6,560)	(26,666)	(3,757)
Net cash provided by (used in) operating activities	433,226	435,757	291,195
INVESTING ACTIVITIES
Proceeds from sales of available for sale securities	792,380	24,380	689,031
Proceeds from maturities/pay downs of available for sale securities	1,899,640	2,032,397	2,515,113
Purchases of available for sale securities	(1,853,817)	(1,988,101)	(3,542,537)
Net (increase) decrease in loans	(614,849)	(1,009,523)	(1,005,657)
Repayments of long-term securities purchased under agreements to resell	(75,000)	(250,000)	0
Proceeds from Securities Purchased under Agreements to Resell	100,000	400,000	175,000
Purchases of land, buildings and equipment	(30,824)	(24,478)	(31,897)
Sales of land, buildings and equipment	3,190	10,112	5,545
Net cash provided by (used in) investing activities	220,720	(805,213)	(1,195,402)
FINANCING ACTIVITIES
Net increase (decrease) in non-interest bearing, savings, interest checking and money market deposits	(15,036)	782,846	545,147
Net increase (decrease) in time open and C.D.’s	(474,044)	243,199	(124,509)
Net increase (decrease) in short-term federal funds purchased and securities sold under agreements to repurchase	(216,767)	(239,647)	101,034
Repayment of other long-term borrowings	(100,291)	(1,769)	(240)
Purchases of treasury stock	(17,771)	(39,381)	(23,176)
Accelerated stock repurchase agreement net outflow	0	0	(100,000)
Issuance of stock under equity compensation plans	(8)	(6)
Proceeds from stock options exercised			1,914
Cash dividends paid on common stock	(91,619)	(87,070)	(84,961)
Cash dividends paid on preferred stock	(9,000)	(9,000)	(9,000)
Net cash provided by (used in) financing activities	(924,536)	649,172	306,209
Increase (decrease) in cash and cash equivalents	(270,590)	279,716	(597,998)
Cash and cash equivalents at beginning of year	782,435	502,719	1,100,717
Cash and cash equivalents at end of year	511,845	782,435	502,719
Supplemental Cash Flow Information:
Income tax payments, net	120,744	119,596	95,341
Interest paid on deposits and borrowings	43,690	31,896	27,760
Loans transferred to foreclosed real estate	2,063	1,122	3,778
Accelerated Share Repurchases, Settlement (Payment) or Receipt	0	0	60,000
Transfer of Portfolio Loans and Leases to Held-for-sale	$ 0	$ 42,688	$ 0

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Non-Controlling Interest
Balance at Dec. 31, 2014	$ 2,334,246	$ 144,784	$ 484,155	$ 1,229,075	$ 426,648	$ (16,562)	$ 62,093	$ 4,053
Net income	266,975				263,730			3,245
Other comprehensive income	(29,623)						(29,623)
Distributions to non-controlling interest	(1,870)							(1,870)
Purchase of treasury stock	(23,176)					(23,176)
Accelerated share repurchase forward contract	(100,000)			60,000		(160,000)
Cash dividends paid on common stock	(84,961)				(84,961)
Cash dividends paid on preferred stock	(9,000)				(9,000)
Net tax benefit related to equity compensation plans	2,132			2,132
Stock-based compensation	10,147			10,147
Issuance under stock purchase and equity compensation plans, net	2,888			(16,615)		19,503
5% stock dividend, net	(340)		5,707	52,938	(213,104)	154,119
Balance at Dec. 31, 2015	2,367,418	144,784	489,862	1,337,677	383,313	(26,116)	32,470	5,428
Net income	276,854				275,391			1,463
Other comprehensive income	(21,495)						(21,495)
Distributions to non-controlling interest	(1,542)							(1,542)
Purchase of treasury stock	(39,381)					(39,381)
Cash dividends paid on common stock	(87,070)				(87,070)
Cash dividends paid on preferred stock	(9,000)				(9,000)
Net tax benefit related to equity compensation plans	3,390			3,390
Stock-based compensation	11,525			11,525
Issuance under stock purchase and equity compensation plans, net	911			(15,810)		16,721
5% stock dividend, net	(478)		20,153	215,672	(269,785)	33,482
Balance at Dec. 31, 2016	2,501,132		510,015	1,552,454	292,849	(15,294)	10,975	5,349
Adoption for ASU 2016-09	1,297			3,441	(2,144)
Net income	319,900				319,383			517
Other comprehensive income	3,133						3,133
Distributions to non-controlling interest	(1,293)							(1,293)
Sale of non-controlling interest in subsidiary	1			2,950				(2,949)
Purchase of treasury stock	(17,771)					(17,771)
Cash dividends paid on common stock	(91,619)				(91,619)
Cash dividends paid on preferred stock	(9,000)				(9,000)
Stock-based compensation	12,105			12,105
Issuance under stock purchase and equity compensation plans, net	858			(17,734)		18,592
5% stock dividend, net	(559)		25,392	262,144	(288,095)
Balance at Dec. 31, 2017	$ 2,718,184	$ 144,784	$ 535,407	$ 1,815,360	$ 221,374	$ (14,473)	$ 14,108	$ 1,624

Consolidated Statements Of Cha8

Consolidated Statements Of Changes In Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Cash dividends paid on common stock (per share)	$ 0.857	$ 0.816	$ 0.777
Cash dividends paid on preferred stock (per share)	$ 1.500	$ 1.500	$ 1.500
Stock dividend rate (percent)	5.00%	5.00%	5.00%

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Nature of Operations Commerce Bancshares, Inc. and its subsidiaries (the Company) conducts its principal activities from approximately 330 locations throughout Missouri, Illinois, Kansas, Oklahoma and Colorado. Principal activities include retail and commercial banking, investment management, securities brokerage, mortgage banking, credit related insurance and private equity investment activities. Basis of Presentation The Company follows accounting principles generally accepted in the United States of America (GAAP) and reporting practices applicable to the banking industry. The preparation of financial statements under GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and notes. These estimates are based on information available to management at the time the estimates are made. While the consolidated financial statements reflect management’s best estimates and judgments, actual results could differ from those estimates. The consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries (after elimination of all material intercompany balances and transactions). Certain prior year amounts have been reclassified to conform to the current year presentation. Such reclassifications had no effect on net income or total assets. Management has evaluated subsequent events for potential recognition or disclosure through the date these consolidated financial statements were issued. The Company, in the normal course of business, engages in a variety of activities that involve variable interest entities (VIEs). A VIE is a legal entity that lacks equity investors or whose equity investors do not have a controlling financial interest in the entity through their equity investments. However, an enterprise is deemed to have a controlling financial interest and is the primary beneficiary of a VIE if it has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. An enterprise that is the primary beneficiary must consolidate the VIE. The Company’s interests in VIEs are evaluated to determine if the Company is the primary beneficiary both at inception and when there is a change in circumstances that requires a reconsideration. The Company is considered to be the primary beneficiary in a rabbi trust related to a deferred compensation plan offered to certain employees. The assets and liabilities of this trust, which are included in the accompanying consolidated balance sheets, are not significant. The Company also has variable interests in certain entities in which it is not the primary beneficiary. These entities are not consolidated. These interests include affordable housing limited partnership interests, holdings in its investment portfolio of various asset and mortgage-backed bonds that are issued by securitization trusts, and managed discretionary trust assets that are not included in the accompanying consolidated balance sheets. Cash and Cash Equivalents In the accompanying consolidated statements of cash flows, cash and cash equivalents include “Cash and due from banks”, “Federal funds sold and short-term securities purchased under agreements to resell”, and “Interest earning deposits with banks” as segregated in the accompanying consolidated balance sheets. Regulations of the Federal Reserve System require cash balances to be maintained at the Federal Reserve Bank, based on certain deposit levels. The minimum reserve requirement for the Bank at December 31, 2017 totaled $126.1 million , while cash held at the Federal Reserve Bank totaled $30.6 million . Additionally, as of December 31, 2017, the Company had $12.5 million in cash collateral on deposit with another financial institution relating to interest rate swap transactions. Loans and Related Earnings Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off are reported at their outstanding principal balances, net of undisbursed loan proceeds, the allowance for loan losses, and any deferred fees and costs on originated loans. Origination fee income received on loans and amounts representing the estimated direct costs of origination are deferred and amortized to interest income over the life of the loan using the interest method. Interest on loans is accrued based upon the principal amount outstanding. Interest income is recognized primarily on the level yield method. Loan and commitment fees, net of costs, are deferred and recognized in income over the term of the loan or commitment as an adjustment of yield. Annual fees charged on credit card loans are capitalized to principal and amortized over 12 months to loan fees and sales. Other credit card fees, such as cash advance fees and late payment fees, are recognized in income as an adjustment of yield when charged to the cardholder’s account. Non-Accrual Loans Loans are placed on non-accrual status when management does not expect to collect payments consistent with acceptable and agreed upon terms of repayment. Business, construction real estate, business real estate, and personal real estate loans that are contractually 90 days past due as to principal and/or interest payments are generally placed on non-accrual, unless they are both well-secured and in the process of collection. Consumer, revolving home equity and credit card loans are exempt under regulatory rules from being classified as non-accrual. When a loan is placed on non-accrual status, any interest previously accrued but not collected is reversed against current income, and the loan is charged off to the extent uncollectible. Principal and interest payments received on non-accrual loans are generally applied to principal. Interest is included in income only after all previous loan charge-offs have been recovered and is recorded only as received. The loan is returned to accrual status only when the borrower has brought all past due principal and interest payments current, and, in the opinion of management, the borrower has demonstrated the ability to make future payments of principal and interest as scheduled. A six month history of sustained payment performance is generally required before reinstatement of accrual status. Restructured Loans A loan is accounted for as a troubled debt restructuring if the Company, for economic or legal reasons related to the borrowers’ financial difficulties, grants a concession to the borrower that it would not otherwise consider. A troubled debt restructuring typically involves (1) modification of terms such as a reduction of the stated interest rate, loan principal, or accrued interest, (2) a loan renewal at a stated interest rate lower than the current market rate for a new loan with similar risk, or (3) debt that was not reaffirmed in bankruptcy. Business, business real estate, construction real estate and personal real estate troubled debt restructurings with impairment charges are placed on non-accrual status. The Company measures the impairment loss of a troubled debt restructuring in the same manner as described below. Troubled debt restructurings which are performing under their contractual terms continue to accrue interest which is recognized in current earnings. Impaired Loans Loans are evaluated regularly by management for impairment. Included in impaired loans are all non-accrual loans, as well as loans that have been classified as troubled debt restructurings. Once a loan has been identified as impaired, impairment is measured based on either the present value of the expected future cash flows at the loan’s initial effective interest rate or the fair value of the collateral if collateral dependent. Factors considered in determining impairment include delinquency status, cash flow analysis, credit analysis, and collateral value and availability. Loans Held For Sale Loans held for sale include student loans and certain fixed rate residential mortgage loans. These loans are typically classified as held for sale upon origination based upon management's intent to sell the production of these loans. The student loans are carried at the lower of aggregate cost or fair value, and their fair value is determined based on sale contract prices. The mortgage loans are carried at fair value under the elected fair value option. Their fair value is based on secondary market prices for loans with similar characteristics, including an adjustment for embedded servicing value. Changes in fair value and gains and losses on sales are included in loan fees and sales. Deferred fees and costs related to these loans are not amortized but are recognized as part of the cost basis of the loan at the time it is sold. Interest income related to loans held for sale is accrued based on the principal amount outstanding and the loan's contractual interest rate. Occasionally, other types of loans may be classified as held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains and losses on sales recognized in loan fees and sales. Allowance/Provision for Loan Losses The allowance for loan losses is maintained at a level believed to be appropriate by management to provide for probable loan losses inherent in the portfolio as of the balance sheet date, including losses on known or anticipated problem loans as well as for loans which are not currently known to require specific allowances. Management has established a process to determine the amount of the allowance for loan losses which assesses the risks and losses inherent in its portfolio. Business, construction real estate and business real estate loans are normally larger and more complex, and their collection rates are harder to predict. These loans are more likely to be collateral dependent and are allocated a larger reserve, due to their potential volatility. Personal real estate, credit card, consumer and revolving home equity loans are individually smaller and perform in a more homogenous manner, making loss estimates more predictable. Management’s process provides an allowance consisting of a specific allowance component based on certain individually evaluated loans and a general component based on estimates of reserves needed for pools of loans. Loans subject to individual evaluation generally consist of business, construction real estate, business real estate and personal real estate loans on non-accrual status. These impaired loans are evaluated individually for the impairment of repayment potential and collateral adequacy. Other impaired loans identified as performing troubled debt restructurings are collectively evaluated because they have similar risk characteristics. Loans which have not been identified as impaired are segregated by loan type and sub-type and are collectively evaluated. Reserves calculated for these loan pools are estimated using a consistent methodology that considers historical loan loss experience by loan type, loss emergence periods, delinquencies, current economic factors, loan risk ratings and industry concentrations. The Company’s estimate of the allowance for loan losses and the corresponding provision for loan losses is based on various judgments and assumptions made by management. The amount of the allowance for loan losses is influenced by several qualitative factors which include collateral valuation, evaluation of performance and status, current loan portfolio composition and characteristics, trends in delinquencies, portfolio risk ratings, levels of non-performing assets, and prevailing regional and national economic and business conditions. The estimates, appraisals, evaluations, and cash flows utilized by management may be subject to frequent adjustments due to changing economic prospects of borrowers or properties. These estimates are reviewed periodically and adjustments, if necessary, are recorded in the provision for loan losses in the periods in which they become known. Loans, or portions of loans, are charged off to the extent deemed uncollectible. Loan charge-offs reduce the allowance for loan losses, and recoveries of loans previously charged off are added back to the allowance. Business, business real estate, construction real estate and personal real estate loans are generally charged down to estimated collectible balances when they are placed on non-accrual status. Consumer loans and related accrued interest are normally charged down to the fair value of related collateral (or are charged off in full if no collateral) once the loans are more than 120 days delinquent. Credit card loans are charged off against the allowance for loan losses when the receivable is more than 180 days past due. The interest and fee income previously capitalized but not collected on credit card charge-offs is reversed against interest income. Operating, Direct Financing and Sales Type Leases The net investment in direct financing and sales type leases is included in loans on the Company’s consolidated balance sheets and consists of the present values of the sum of the future minimum lease payments and estimated residual value of the leased asset. Revenue consists of interest earned on the net investment and is recognized over the lease term as a constant percentage return thereon. The net investment in operating leases is included in other assets on the Company’s consolidated balance sheets. It is carried at cost, less the amount depreciated to date. Depreciation is recognized, on the straight-line basis, over the lease term to the estimated residual value. Operating lease revenue consists of the contractual lease payments and is recognized over the lease term in other non-interest income. Estimated residual values are established at lease inception utilizing contract terms, past customer experience, and general market data and are reviewed and adjusted, if necessary, on an annual basis. Investments in Debt and Equity Securities The Company has classified the majority of its investment portfolio as available for sale. From time to time, the Company sells securities and utilizes the proceeds to reduce borrowings, fund loan growth, or modify its interest rate profile. Securities classified as available for sale are carried at fair value. Changes in fair value, excluding certain losses associated with other-than-temporary impairment (OTTI), are reported in other comprehensive income (loss), a component of stockholders’ equity. Securities are periodically evaluated for OTTI in accordance with guidance provided in ASC 320-10-35. For securities with OTTI, the entire loss in fair value is required to be recognized in current earnings if the Company intends to sell the securities or believes it likely that it will be required to sell the security before the anticipated recovery. If neither condition is met, but the Company does not expect to recover the amortized cost basis, the Company determines whether a credit loss has occurred, and the loss is then recognized in current earnings. The noncredit-related portion of the overall loss is reported in other comprehensive income (loss). Gains and losses realized upon sales of securities are calculated using the specific identification method and are included in investment securities gains (losses), net, in the consolidated statements of income. Purchase premiums and discounts are amortized to interest income using a level yield method over the estimated lives of the securities. For mortgage and asset-backed securities, prepayment experience is evaluated quarterly to determine the appropriate estimate of the future rate of prepayment. When a change in a bond's estimated remaining life is necessary, a corresponding adjustment is made in the related amortization of premium or discount accretion. Non-marketable securities include certain private equity investments, consisting of both debt and equity instruments. These securities are carried at fair value in accordance with ASC 946-10-15, with changes in fair value reported in current earnings. In the absence of readily ascertainable market values, fair value is estimated using internally developed models. Changes in fair value and gains and losses from sales are included in investment securities gains (losses), net in the consolidated statements of income. Other non-marketable securities acquired for debt and regulatory purposes are carried at cost and periodically evaluated for other-than-temporary impairment. Trading account securities, which are bought and held principally for the purpose of resale in the near term, are carried at fair value. Gains and losses, both realized and unrealized, are recorded in non-interest income. Purchases and sales of securities are recognized on a trade date basis. A receivable or payable is recognized for pending transaction settlements. Securities Purchased under Agreements to Resell and Securities Sold under Agreements to Repurchase Securities purchased under agreements to resell and securities sold under agreements to repurchase are treated as collateralized financing transactions, not as purchases and sales of the underlying securities. The agreements are recorded at the amount of cash advanced or received. The Company periodically enters into securities purchased under agreements to resell with large financial institutions. Securities pledged by the counterparties to secure these agreements are delivered to a third party custodian. Securities sold under agreements to repurchase are a source of funding to the Company and are offered to cash management customers as an automated, collateralized investment account. From time to time, securities sold may also be used by the Bank to obtain additional borrowed funds at favorable rates. These borrowings are secured by a portion of the Company's investment security portfolio and delivered either to the dealer custody account at the FRB or to the applicable counterparty. The fair value of collateral either received from or provided to a counterparty is monitored daily, and additional collateral is obtained, returned, or provided by the Company in order to maintain full collateralization for these transactions. As permitted by current accounting guidance, the Company offsets certain securities purchased under agreements to resell against securities sold under agreements to repurchase in its balance sheet presentation. These agreements are further discussed in Note 18, Resale and Repurchase Agreements. Land, Buildings and Equipment Land is stated at cost, and buildings and equipment are stated at cost, including capitalized interest when appropriate, less accumulated depreciation. Depreciation is computed using a straight-line method, utilizing estimated useful lives; generally 30 years for buildings, 10 years for building improvements, and 3 to 10 years for equipment. Leasehold improvements are amortized over the shorter of 10 years or the remaining lease term. Maintenance and repairs are charged to non-interest expense as incurred. Foreclosed Assets Foreclosed assets consist of property that has been repossessed and is comprised of commercial and residential real estate and other non-real estate property, including auto and recreational and marine vehicles. The assets are initially recorded at fair value less estimated selling costs, establishing a new cost basis. Initial valuation adjustments are charged to the allowance for loan losses. Fair values are estimated primarily based on appraisals, third-party price opinions, or internally developed pricing models. After initial recognition, fair value estimates are updated periodically. Declines in fair value below cost are recognized through valuation allowances which may be reversed when supported by future increases in fair value. These valuation adjustments, in addition to gains and losses realized on sales and net operating expenses, are recorded in other non-interest expense. Goodwill and Intangible Assets Goodwill is not amortized but is assessed for impairment on an annual basis or more frequently in certain circumstances. When testing for goodwill impairment, the Company may initially perform a qualitative assessment. Based on the results of this qualitative assessment, if the Company concludes it is more likely than not that a reporting unit's fair value is less than its carrying amount, a quantitative analysis is performed. Quantitative valuation methodologies include a combination of formulas using current market multiples, based on recent sales of financial institutions within the Company's geographic marketplace. If the fair value of a reporting unit is less than the carrying amount, additional analysis is required to measure the amount of impairment. The Company has not recorded impairment resulting from goodwill impairment tests. However, adverse changes in the economic environment, operations of the reporting unit, or other factors could result in a decline in fair value. Intangible assets that have finite useful lives, such as core deposit intangibles and mortgage servicing rights, are amortized over their estimated useful lives. Core deposit intangibles are amortized over periods of 8 to 14 years, representing their estimated lives, using accelerated methods. Mortgage servicing rights are amortized in proportion to and over the period of estimated net servicing income, considering appropriate prepayment assumptions. Core deposit intangibles are reviewed for impairment whenever events or changes in circumstances indicate their carrying amount may not be recoverable. Impairment is indicated if the sum of the undiscounted estimated future net cash flows is less than the carrying value of the intangible asset. Mortgage servicing rights, while initially recorded at fair value, are subsequently amortized and carried at the lower of the initial capitalized amount (net of accumulated amortization), or estimated fair value. The Company evaluates its mortgage servicing rights for impairment on a quarterly basis, using estimated prepayment speeds of the underlying mortgage loans serviced and stratifications based on the risk characteristics of the underlying loans. A valuation allowance has been established, through a charge to earnings, to the extent the amortized cost exceeds the estimated fair value. However, the Company has not recorded other-than-temporary impairment losses on either of these types of intangible assets. Income Taxes Amounts provided for income tax expense are based on income reported for financial statement purposes and do not necessarily represent amounts currently payable under tax laws. Deferred income taxes are provided for temporary differences between the financial reporting bases and income tax bases of the Company’s assets and liabilities, net operating losses, and tax credit carryforwards. Deferred tax assets and liabilities are measured using the enacted tax rates that are expected to apply to taxable income when such assets and liabilities are anticipated to be settled or realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized as tax expense or benefit in the period that includes the enactment date of the change. In determining the amount of deferred tax assets to recognize in the financial statements, the Company evaluates the likelihood of realizing such benefits in future periods. A valuation allowance is established if it is more likely than not that all or some portion of the deferred tax asset will not be realized. The Company recognizes interest and penalties related to income taxes within income tax expense in the consolidated statements of income. The Company and its eligible subsidiaries file a consolidated federal income tax return. State and local income tax returns are filed on a combined, consolidated or separate return basis based upon each jurisdiction’s laws and regulations. In December 2017, tax reform legislation was enacted which changed the maximum corporate tax rate for years 2018 and beyond. As such, deferred tax assets and liabilities were revalued in 2017 to account for the change in future tax rates. Additional information about current and deferred income taxes is provided in Note 8, Income Taxes. Derivatives While the Company’s interest rate risk management policy permits the use of hedge accounting for derivatives, all of the derivatives held by the Company during the past several years have been accounted for as free-standing instruments. These instruments are carried at fair value, and changes in fair value are recognized in current earnings. They include interest rate swaps and caps, which are offered to customers to assist in managing their risks of adverse changes in interest rates. Each contract between the Company and a customer is offset by a contract between the Company and an institutional counterparty, thus minimizing the Company's exposure to rate changes. The Company also enters into certain contracts, known as credit risk participation agreements, to buy or sell credit protection on specific interest rate swaps. It also purchases and sells forward foreign exchange contracts, either in connection with customer transactions, or for its own trading purposes. In 2015, the Company began an origination and sales program of certain personal real estate mortgages. Derivative instruments under this program include mortgage loan commitments, forward loan sale contracts, and forward contracts to sell certain to-be-announced (TBA) securities. The Company has master netting arrangements with various counterparties but does not offset derivative assets and liabilities under these arrangements in its consolidated balance sheets. However, interest rate swaps that are executed under central clearing requirements are presented on a net basis as mandated by the statutory terms of the Company's contract with its clearing counterparty. Additional information about derivatives held by the Company and valuation methods employed is provided in Note 15, Fair Value Measurements and Note 17, Derivative Instruments. Pension Plan The Company’s pension plan is described in Note 9, Employee Benefit Plans. The funded status of the plan is recognized as an asset or liability in the consolidated balance sheets, and changes in that funded status are recognized in the year in which the changes occur through other comprehensive income. Plan assets and benefit obligations are measured as of fiscal year end. The measurement of the projected benefit obligation and pension expense involve actuarial valuation methods and the use of various actuarial and economic assumptions. The Company monitors the assumptions and updates them periodically. Due to the long-term nature of the pension plan obligation, actual results may differ significantly from estimations. Such differences are adjusted over time as the assumptions are replaced by facts and values are recalculated. Stock-Based Compensation The Company’s stock-based employee compensation plan is described in Note 10, Stock-Based Compensation and Directors Stock Purchase Plan. In accordance with the requirements of ASC 718-10-30-3 and 35-2, the Company measures the cost of stock-based compensation based on the grant-date fair value of the award, recognizing the cost over the requisite service period, which is generally the vesting period. The fair value of an option award is estimated using the Black-Scholes option-pricing model while the fair value of a nonvested stock award is the common stock (CBSH) market price. The expense recognized is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occurred, and was included in salaries and employee benefits in the accompanying consolidated statements of income. As further discussed in Note 10, effective January 1, 2017, the Company recognized forfeitures as a reduction to expense only when they have occurred, as allowed under the provisions of ASU 2016-09. Comprehensive Income Comprehensive income includes all changes in stockholders’ equity during a period, except those resulting from transactions with stockholders. In addition to net income, other components of the Company’s comprehensive income include the after tax effect of changes in net unrealized gain / loss on securities available for sale and changes in net actuarial gain / loss on defined benefit post-retirement plans. Comprehensive income is reported in the accompanying consolidated statements of comprehensive income. See Note 11 for additional information on accumulated other comprehensive income (loss). Treasury Stock Purchases of the Company’s common stock are recorded at cost. Upon re-issuance for acquisitions, exercises of stock-based awards or other corporate purposes, treasury stock is reduced based upon the average cost basis of shares held. Income per Share Basic income per share is computed using the weighted average number of common shares outstanding during each year. Diluted income per share includes the effect of all dilutive potential common shares (primarily stock options and stock appreciation rights) outstanding during each year. The Company applies the two-class method of computing income per share. The two-class method is an earnings allocation formula that determines income per share for common stock and for participating securities, according to dividends declared and participation rights in undistributed earnings. The Company’s nonvested stock awards are considered to be a class of participating security. All per share data has been restated to reflect the 5% stock dividend distributed in December 2017 .

Loans And Allowance For Loan Lo

Loans And Allowance For Loan Losses	12 Months Ended
	Dec. 31, 2017
Loans And Allowance For Loan Losses [Abstract]
Loans And Allowance For Loan Losses	Loans and Allowance for Loan Losses Major classifications within the Company’s held for investment loan portfolio at December 31, 2017 and 2016 are as follows: (In thousands) 2017 2016 Commercial: Business $ 4,958,554 $ 4,776,365 Real estate — construction and land 968,820 791,236 Real estate — business 2,697,452 2,643,374 Personal Banking: Real estate — personal 2,062,787 2,010,397 Consumer 2,104,487 1,990,801 Revolving home equity 400,587 413,634 Consumer credit card 783,864 776,465 Overdrafts 7,123 10,464 Total loans $ 13,983,674 $ 13,412,736 Loans to directors and executive officers of the Parent and the Bank, and to their associates, are summarized as follows: (In thousands) Balance at January 1, 2017 $ 62,991 Additions 655,544 Amounts collected (639,920 ) Amounts written off — Balance, December 31, 2017 $ 78,615 Management believes all loans to directors and executive officers have been made in the ordinary course of business with normal credit terms, including interest rate and collateral considerations, and do not represent more than a normal risk of collection. The activity in the table above includes draws and repayments on several lines of credit with business entities. There were no outstanding loans at December 31, 2017 to principal holders (over 10% ownership) of the Company’s common stock. The Company’s lending activity is generally centered in Missouri, Illinois, Kansas and other nearby states including Oklahoma, Colorado, Iowa, Ohio, Texas, and others. The Company maintains a diversified portfolio with limited industry concentrations of credit risk. Loans and loan commitments are extended under the Company’s normal credit standards, controls, and monitoring features. Most loan commitments are short or intermediate term in nature. Commercial loan maturities generally range from three to seven years. Collateral is commonly required and would include such assets as marketable securities and cash equivalent assets, accounts receivable and inventory, equipment, other forms of personal property, and real estate. At December 31, 2017 , unfunded loan commitments totaled $10.8 billion (which included $5.1 billion in unused approved lines of credit related to credit card loan agreements) which could be drawn by customers subject to certain review and terms of agreement. At December 31, 2017 , loans totaling $ 3.8 billion were pledged at the FHLB as collateral for borrowings and letters of credit obtained to secure public deposits. Additional loans of $ 1.7 billion were pledged at the Federal Reserve Bank as collateral for discount window borrowings. The Company has a net investment in direct financing and sales type leases to commercial and industrial and tax-exempt entities of $737.7 million and $725.3 million at December 31, 2017 and 2016 , respectively, which is included in business loans on the Company’s consolidated balance sheets. This investment includes deferred income of $52.1 million and $49.9 million at December 31, 2017 and 2016 , respectively. The net investment in operating leases amounted to $17.4 million and $19.0 million at December 31, 2017 and 2016 , respectively, and is included in other assets on the Company’s consolidated balance sheets. Allowance for loan losses A summary of the activity in the allowance for losses during the previous three years follows: (In thousands) Commercial Personal Banking Total Balance at December 31, 2014 $ 89,622 $ 66,910 $ 156,532 Provision for loan losses (9,319 ) 38,046 28,727 Deductions: Loans charged off 4,057 46,993 51,050 Less recoveries 5,840 11,483 17,323 Net loans charged off (recoveries) (1,783 ) 35,510 33,727 Balance at December 31, 2015 82,086 69,446 151,532 Provision for loan losses 4,898 31,420 36,318 Deductions: Loans charged off 3,258 47,720 50,978 Less recoveries 7,635 11,425 19,060 Net loans charged off (recoveries) (4,377 ) 36,295 31,918 Balance at December 31, 2016 91,361 64,571 155,932 Provision for loan losses 2,327 42,917 45,244 Deductions: Loans charged off 2,538 52,641 55,179 Less recoveries 2,554 10,981 13,535 Net loans charged off (recoveries) (16 ) 41,660 41,644 Balance at December 31, 2017 $ 93,704 $ 65,828 $ 159,532 The following table shows the balance in the allowance for loan losses and the related loan balance at December 31, 2017 and 2016 , disaggregated on the basis of impairment methodology. Impaired loans evaluated under ASC 310-10-35 include loans on non-accrual status which are individually evaluated for impairment and other impaired loans deemed to have similar risk characteristics, which are collectively evaluated. All other loans are collectively evaluated for impairment under ASC 450-20. Impaired Loans All Other Loans (In thousands) Allowance for Loan Losses Loans Outstanding Allowance for Loan Losses Loans Outstanding December 31, 2017 Commercial $ 3,067 $ 92,613 $ 90,637 $ 8,532,213 Personal Banking 1,176 22,182 64,652 5,336,666 Total $ 4,243 $ 114,795 $ 155,289 $ 13,868,879 December 31, 2016 Commercial $ 1,817 $ 44,795 $ 89,544 $ 8,166,180 Personal Banking 1,292 19,737 63,279 5,182,024 Total $ 3,109 $ 64,532 $ 152,823 $ 13,348,204 Impaired loans The table below shows the Company’s investment in impaired loans at December 31, 2017 and 2016 . These loans consist of all loans on non-accrual status and other restructured loans whose terms have been modified and classified as troubled debt restructurings under current accounting guidance. These restructured loans are performing in accordance with their modified terms, and because the Company believes it probable that all amounts due under the modified terms of the agreements will be collected, interest on these loans is being recognized on an accrual basis. They are discussed further in the "Troubled debt restructurings" section on page 78. (In thousands) 2017 2016 Non-accrual loans $ 11,983 $ 14,283 Restructured loans (accruing) 102,812 50,249 Total impaired loans $ 114,795 $ 64,532 The following table provides additional information about impaired loans held by the Company at December 31, 2017 and 2016 , segregated between loans for which an allowance for credit losses has been provided and loans for which no allowance has been provided. (In thousands) Recorded Investment Unpaid Principal Balance Related Allowance December 31, 2017 With no related allowance recorded: Business $ 5,356 $ 9,000 $ — Real estate – business 1,299 1,303 — Consumer 779 817 — $ 7,434 $ 11,120 $ — With an allowance recorded: Business $ 72,589 $ 73,168 $ 2,455 Real estate – construction and land 837 841 27 Real estate – business 12,532 13,071 585 Real estate – personal 9,126 11,914 532 Consumer 5,388 5,426 67 Revolving home equity 204 204 11 Consumer credit card 6,685 6,685 566 $ 107,361 $ 111,309 $ 4,243 Total $ 114,795 $ 122,429 $ 4,243 December 31, 2016 With no related allowance recorded: Business $ 7,375 $ 10,470 $ — Real estate – construction and land 557 752 — $ 7,932 $ 11,222 $ — With an allowance recorded: Business $ 29,924 $ 31,795 $ 1,318 Real estate – construction and land 69 72 3 Real estate – business 6,870 8,072 496 Real estate – personal 6,394 9,199 642 Consumer 5,281 5,281 57 Revolving home equity 584 584 1 Consumer credit card 7,478 7,478 592 $ 56,600 $ 62,481 $ 3,109 Total $ 64,532 $ 73,703 $ 3,109 Total average impaired loans during 2017 and 2016 are shown in the table below. 2017 2016 (In thousands) Commercial Personal Banking Total Commercial Personal Banking Total Average impaired loans: Non-accrual loans $ 9,658 $ 3,989 $ 13,647 $ 17,294 $ 4,135 $ 21,429 Restructured loans (accruing) 49,070 17,539 66,609 32,295 17,058 49,353 Total $ 58,728 $ 21,528 $ 80,256 $ 49,589 $ 21,193 $ 70,782 The table below shows interest income recognized during the years ended December 31, 2017 , 2016 and 2015 for impaired loans held at the end of each respective period. This interest relates to accruing restructured loans, as discussed previously. Years Ended December 31 (In thousands) 2017 2016 2015 Interest income recognized on impaired loans: Business $ 3,135 $ 1,064 $ 495 Real estate – construction and land 41 2 80 Real estate – business 514 171 122 Real estate – personal 402 152 187 Consumer 307 339 348 Revolving home equity 10 31 20 Consumer credit card 673 722 750 Total $ 5,082 $ 2,481 $ 2,002 Delinquent and non-accrual loans The following table provides aging information on the Company’s past due and accruing loans, in addition to the balances of loans on non-accrual status, at December 31, 2017 and 2016 . (In thousands) Current or Less Than 30 Days Past Due 30 – 89 Days Past Due 90 Days Past Due and Still Accruing Non-accrual Total December 31, 2017 Commercial: Business $ 4,949,148 $ 3,085 $ 374 $ 5,947 $ 4,958,554 Real estate – construction and land 967,321 1,473 21 5 968,820 Real estate – business 2,694,234 482 — 2,736 2,697,452 Personal Banking: Real estate – personal 2,050,787 6,218 3,321 2,461 2,062,787 Consumer 2,067,025 32,674 3,954 834 2,104,487 Revolving home equity 397,349 1,962 1,276 — 400,587 Consumer credit card 764,568 10,115 9,181 — 783,864 Overdrafts 6,840 283 — — 7,123 Total $ 13,897,272 $ 56,292 $ 18,127 $ 11,983 $ 13,983,674 December 31, 2016 Commercial: Business $ 4,763,274 $ 3,735 $ 674 $ 8,682 $ 4,776,365 Real estate – construction and land 789,633 1,039 — 564 791,236 Real estate – business 2,639,586 2,154 — 1,634 2,643,374 Personal Banking: Real estate – personal 1,995,724 9,162 2,108 3,403 2,010,397 Consumer 1,957,358 29,783 3,660 — 1,990,801 Revolving home equity 411,483 1,032 1,119 — 413,634 Consumer credit card 757,443 10,187 8,835 — 776,465 Overdrafts 10,014 450 — — 10,464 Total $ 13,324,515 $ 57,542 $ 16,396 $ 14,283 $ 13,412,736 Credit quality The following table provides information about the credit quality of the Commercial loan portfolio, using the Company’s internal rating system as an indicator. The internal rating system is a series of grades reflecting management’s risk assessment, based on its analysis of the borrower’s financial condition. The “pass” category consists of a range of loan grades that reflect increasing, though still acceptable, risk. Movement of risk through the various grade levels in the “pass” category is monitored for early identification of credit deterioration. The “special mention” rating is attached to loans where the borrower exhibits material negative financial trends due to borrower specific or systemic conditions that, if left uncorrected, threaten its capacity to meet its debt obligations. The borrower is believed to have sufficient financial flexibility to react to and resolve its negative financial situation. It is a transitional grade that is closely monitored for improvement or deterioration. The “substandard” rating is applied to loans where the borrower exhibits well-defined weaknesses that jeopardize its continued performance and are of a severity that the distinct possibility of default exists. Loans are placed on “non-accrual” when management does not expect to collect payments consistent with acceptable and agreed upon terms of repayment, as discussed in Note 1. Commercial Loans (In thousands) Business Real Estate -Construction Real Estate - Business Total December 31, 2017 Pass $ 4,740,013 $ 955,499 $ 2,593,005 $ 8,288,517 Special mention 59,177 10,614 50,577 120,368 Substandard 153,417 2,702 51,134 207,253 Non-accrual 5,947 5 2,736 8,688 Total $ 4,958,554 $ 968,820 $ 2,697,452 $ 8,624,826 December 31, 2016 Pass $ 4,607,553 $ 788,778 $ 2,543,348 $ 7,939,679 Special mention 116,642 722 45,479 162,843 Substandard 43,488 1,172 52,913 97,573 Non-accrual 8,682 564 1,634 10,880 Total $ 4,776,365 $ 791,236 $ 2,643,374 $ 8,210,975 The credit quality of Personal Banking loans is monitored primarily on the basis of aging/delinquency, and this information is provided in the table in the above section on "Delinquent and non-accrual loans" . In addition, FICO scores are obtained and updated on a quarterly basis for most of the loans in the Personal Banking portfolio. This is a published credit score designed to measure the risk of default by taking into account various factors from a person's financial history. The bank normally obtains a FICO score at the loan's origination and renewal dates, and updates are obtained on a quarterly basis. Excluded from the table below are certain personal real estate loans for which FICO scores are not obtained because the loans are related to commercial activity. These loans totaled $219.2 million at December 31, 2017 and $237.2 million at December 31, 2016 . The table also excludes consumer loans related to the Company's patient healthcare loan program, which totaled $145.0 million at December 31, 2017 and $75.4 million at December 31, 2016 . As the healthcare loans are guaranteed by the hospital, FICO scores are not considered relevant for this program. The personal real estate loans and consumer loans excluded below totaled less than 7% of the Personal Banking portfolio. For the remainder of loans in the Personal Banking portfolio, the table below shows the percentage of balances outstanding at December 31, 2017 and 2016 by FICO score. Personal Banking Loans % of Loan Category Real Estate - Personal Consumer Revolving Home Equity Consumer Credit Card December 31, 2017 FICO score: Under 600 1.3 % 3.3 % 1.1 % 4.7 % 600 – 659 2.1 5.5 1.7 14.4 660 – 719 10.5 17.3 9.5 34.4 720 – 779 25.6 26.8 21.4 26.0 780 and over 60.5 47.1 66.3 20.5 Total 100.0 % 100.0 % 100.0 % 100.0 % December 31, 2016 FICO score: Under 600 1.3 % 3.4 % 1.0 % 4.9 % 600 – 659 2.6 6.4 1.8 15.5 660 – 719 10.4 19.7 9.7 34.9 720 – 779 25.4 26.3 21.1 25.1 780 and over 60.3 44.2 66.4 19.6 Total 100.0 % 100.0 % 100.0 % 100.0 % Troubled debt restructurings As mentioned previously, the Company's impaired loans include loans which have been classified as troubled debt restructurings. Restructured loans are those extended to borrowers who are experiencing financial difficulty and who have been granted a concession. Restructured loans are placed on non-accrual status if the Company does not believe it probable that amounts due under the contractual terms will be collected. Other performing restructured loans are comprised of certain business, construction and business real estate loans classified as substandard. Upon maturity, the loans renewed at interest rates judged not to be market rates for new debt with similar risk and as a result were classified as troubled debt restructurings. These loans are performing in accordance with their modified terms, and because the Company believes it probable that all amounts due under the modified terms of the agreements will be collected, interest on these loans is being recognized on an accrual basis. Performing restructured loans at rates judged to be below market increased $54.1 million at year end 2017 compared to year end 2016 due to several large loan renewals in 2017, including a single business loan of $31.9 million . Troubled debt restructurings also include certain credit card loans under various debt management and assistance programs. Modifications to credit card loans generally involve removing the available line of credit, placing loans on amortizing status, and lowering the contractual interest rate. The Company also classified certain loans as troubled debt restructurings because they were not reaffirmed by the borrower in bankruptcy proceedings. These loans are comprised of personal real estate, revolving home equity and consumer loans. Interest on these loans is being recognized on an accrual basis, as the borrowers are continuing to make payments. The table below summarizes the troubled debt restructurings outstanding by type of modification, as described above. December 31 (In thousands) 2017 2016 Accruing loans: Non-market interest rates $ 88,588 $ 34,531 Assistance programs 6,685 7,478 Bankruptcy non-affirmation 7,283 7,937 Other 256 303 Non-accrual loans 7,796 8,825 Total restructured loans $ 110,608 $ 59,074 The table below shows the balance of troubled debt restructurings by loan classification at December 31, 2017 , in addition to the period end balances of restructured loans which the Company considers to have been in default at any time during the past twelve months. For purposes of this disclosure, the Company considers "default" to mean 90 days or more past due as to interest or principal. (In thousands) December 31, 2017 Balance 90 days past due at any time during previous 12 months Commercial: Business $ 77,400 $ — Real estate – construction and land 776 — Real estate – business 12,394 — Personal Banking: Real estate – personal 7,760 278 Consumer 5,389 81 Revolving home equity 204 42 Consumer credit card 6,685 630 Total restructured loans $ 110,608 $ 1,031 For those loans on non-accrual status also classified as restructured, the modification did not create any further financial effect on the Company as those loans were already recorded at net realizable value. For those performing commercial loans classified as restructured, there were no concessions involving forgiveness of principal or interest and, therefore, there was no financial impact to the Company as a result of modification to these loans. No financial impact resulted from those performing loans where the debt was not reaffirmed in bankruptcy, as no changes to loan terms occurred in that process. However, the effects of modifications to consumer credit card loans were estimated to decrease interest income by approximately $1.0 million on an annual, pre-tax basis, compared to amounts contractually owed. The allowance for loan losses related to troubled debt restructurings on non-accrual status is determined by individual evaluation, including collateral adequacy, using the same process as loans on non-accrual status which are not classified as troubled debt restructurings. Those performing loans classified as troubled debt restructurings are accruing loans which management expects to collect under contractual terms. Performing commercial loans have had no other concessions granted other than being renewed at an interest rate judged not to be market. As such, they have similar risk characteristics as non-troubled debt commercial loans and are collectively evaluated based on internal risk rating, loan type, delinquency, historical experience and current economic factors. Performing personal banking loans classified as troubled debt restructurings resulted from the borrower not reaffirming the debt during bankruptcy and have had no other concession granted, other than the Bank's future limitations on collecting payment deficiencies or in pursuing foreclosure actions. As such, they have similar risk characteristics as non-troubled debt personal banking loans and are evaluated collectively based on loan type, delinquency, historical experience and current economic factors. If a troubled debt restructuring defaults and is already on non-accrual status, the allowance for loan losses continues to be based on individual evaluation, using discounted expected cash flows or the fair value of collateral. If an accruing, troubled debt restructuring defaults, the loan's risk rating is downgraded to non-accrual status and the loan's related allowance for loan losses is determined based on individual evaluation, or if necessary, the loan is charged off and collection efforts begin. The Company had commitments of $7.6 million at December 31, 2017 to lend additional funds to borrowers with restructured loans, compared to $10.3 million at December 31, 2016 . Loans held for sale The Company designates certain long-term fixed rate personal real estate loan originations as held for sale, and the Company has elected the fair value option for these loans. The election of the fair value option aligns the accounting for these loans with the related economic hedges discussed in Note 17. The loans are primarily sold to FNMA, FHLMC, and GNMA. At December 31, 2017 , the fair value of these loans was $15.3 million , and the unpaid principal balance was $14.8 million . The Company also designates certain student loan originations as held for sale. The borrowers are credit-worthy students who are attending colleges and universities. The loans are intended to be sold in the secondary market, and the Company maintains contracts with Sallie Mae to sell the loans within 210 days after the last disbursement to the student. These loans are carried at lower of cost or fair value, which at December 31, 2017 totaled $6.1 million . At December 31, 2017, none of the loans held for sale were past due or on non-accrual status. Foreclosed real estate/repossessed assets The Company’s holdings of foreclosed real estate totaled $681 thousand and $366 thousand at December 31, 2017 and 2016 , respectively. Personal property acquired in repossession, generally autos and marine and recreational vehicles, totaled $2.7 million and $2.2 million at December 31, 2017 and 2016 , respectively. Upon acquisition, these assets are recorded at fair value less estimated selling costs at the date of foreclosure, establishing a new cost basis. They are subsequently carried at the lower of this cost basis or fair value less estimated selling costs.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities Investment securities, at fair value, consisted of the following at December 31, 2017 and 2016 . (In thousands) 2017 2016 Available for sale: U.S. government and federal agency obligations $ 917,147 $ 920,904 Government-sponsored enterprise obligations 406,363 449,998 State and municipal obligations 1,611,366 1,778,214 Agency mortgage-backed securities 3,040,913 2,685,931 Non-agency mortgage-backed securities 905,793 1,055,639 Asset-backed securities 1,492,800 2,381,301 Other debt securities 351,060 325,953 Equity securities 48,838 51,263 Total available for sale 8,774,280 9,649,203 Trading 18,269 22,225 Non-marketable 100,758 99,558 Total investment securities $ 8,893,307 $ 9,770,986 Most of the Company’s investment securities are classified as available for sale, and this portfolio is discussed in more detail below. Securities which are classified as non-marketable include Federal Home Loan Bank (FHLB) stock and Federal Reserve Bank stock held for borrowing and regulatory purposes, which totaled $43.3 million and $46.9 million at December 31, 2017 and 2016 , respectively. Investment in Federal Reserve Bank stock is based on the capital structure of the investing bank, and investment in FHLB stock is mainly tied to the level of borrowings from the FHLB. These holdings are carried at cost. Non-marketable securities also include private equity investments, which amounted to $57.2 million and $52.3 million at December 31, 2017 and 2016 , respectively. In the absence of readily ascertainable market values, these securities are carried at estimated fair value. A summary of the available for sale investment securities by maturity groupings as of December 31, 2017 is shown in the following table. The weighted average yield for each range of maturities was calculated using the yield on each security within that range weighted by the amortized cost of each security at December 31, 2017 . Yields on tax exempt securities have not been adjusted for tax exempt status. The investment portfolio includes agency mortgage-backed securities, which are guaranteed by agencies such as FHLMC, FNMA, GNMA and FDIC, in addition to non-agency mortgage-backed securities which have no guarantee, but are collateralized by residential and commercial mortgages. Also included are certain other asset-backed securities, primarily collateralized by credit cards, automobiles and commercial loans. The Company does not have exposure to subprime-originated mortgage-backed or collateralized debt obligation instruments, and does not hold any trust preferred securities. (Dollars in thousands) Amortized Cost Fair Value Weighted Average Yield U.S. government and federal agency obligations: Within 1 year $ 57,983 $ 58,347 1.71 After 1 but within 5 years 641,114 639,192 1.45 After 5 but within 10 years 149,589 149,927 .43 After 10 years 68,808 69,681 .59 Total U.S. government and federal agency obligations 917,494 917,147 1.24 Government-sponsored enterprise obligations: Within 1 year 215,763 215,434 1.35 After 1 but within 5 years 121,575 121,199 1.93 After 5 but within 10 years 34,983 34,870 2.71 After 10 years 35,945 34,860 3.00 Total government-sponsored enterprise obligations 408,266 406,363 1.79 State and municipal obligations: Within 1 year 164,756 165,638 2.65 After 1 but within 5 years 665,351 670,953 2.21 After 5 but within 10 years 709,248 721,181 2.46 After 10 years 53,352 53,594 3.01 Total state and municipal obligations 1,592,707 1,611,366 2.39 Mortgage and asset-backed securities: Agency mortgage-backed securities 3,046,701 3,040,913 2.62 Non-agency mortgage-backed securities 903,920 905,793 2.54 Asset-backed securities 1,495,380 1,492,800 2.03 Total mortgage and asset-backed securities 5,446,001 5,439,506 2.45 Other debt securities: Within 1 year 10,390 10,389 After 1 but within 5 years 247,181 247,626 After 5 but within 10 years 93,417 93,045 Total other debt securities 350,988 351,060 Equity securities 4,411 48,838 Total available for sale investment securities $ 8,719,867 $ 8,774,280 * Rate does not reflect inflation adjustment on inflation-protected securities Investments in U.S. government securities include U.S. Treasury inflation-protected securities, which totaled $442.1 million , at fair value, at December 31, 2017 . Interest paid on these securities increases with inflation and decreases with deflation, as measured by the Consumer Price Index. At maturity, the principal paid is the greater of an inflation-adjusted principal or the original principal. Included in state and municipal obligations are $17.0 million , at fair value, of auction rate securities, which were purchased from bank customers in 2008. Interest on these bonds is currently being paid at the maximum failed auction rates. Equity securities are primarily comprised of investments in common stock held by the Parent, which totaled $45.9 million , at fair value, at December 31, 2017 . For securities classified as available for sale, the following table shows the unrealized gains and losses (pre-tax) in accumulated other comprehensive income, by security type. (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value December 31, 2017 U.S. government and federal agency obligations $ 917,494 $ 4,096 $ (4,443 ) $ 917,147 Government-sponsored enterprise obligations 408,266 26 (1,929 ) 406,363 State and municipal obligations 1,592,707 21,413 (2,754 ) 1,611,366 Mortgage and asset-backed securities: Agency mortgage-backed securities 3,046,701 17,956 (23,744 ) 3,040,913 Non-agency mortgage-backed securities 903,920 6,710 (4,837 ) 905,793 Asset-backed securities 1,495,380 2,657 (5,237 ) 1,492,800 Total mortgage and asset-backed securities 5,446,001 27,323 (33,818 ) 5,439,506 Other debt securities 350,988 1,250 (1,178 ) 351,060 Equity securities 4,411 44,427 — 48,838 Total $ 8,719,867 $ 98,535 $ (44,122 ) $ 8,774,280 December 31, 2016 U.S. government and federal agency obligations $ 919,904 $ 7,312 $ (6,312 ) $ 920,904 Government-sponsored enterprise obligations 450,448 1,126 (1,576 ) 449,998 State and municipal obligations 1,778,684 12,223 (12,693 ) 1,778,214 Mortgage and asset-backed securities: Agency mortgage-backed securities 2,674,964 31,610 (20,643 ) 2,685,931 Non-agency mortgage-backed securities 1,054,446 7,686 (6,493 ) 1,055,639 Asset-backed securities 2,389,176 3,338 (11,213 ) 2,381,301 Total mortgage and asset-backed securities 6,118,586 42,634 (38,349 ) 6,122,871 Other debt securities 327,030 935 (2,012 ) 325,953 Equity securities 5,678 45,585 — 51,263 Total $ 9,600,330 $ 109,815 $ (60,942 ) $ 9,649,203 The Company’s impairment policy requires a review of all securities for which fair value is less than amortized cost. Special emphasis and analysis is placed on securities whose credit rating has fallen below Baa3 (Moody's) or BBB- (Standard & Poor's), whose fair values have fallen more than 20% below purchase price for an extended period of time, or have been identified based on management’s judgment. These securities are placed on a watch list, and for all such securities, detailed cash flow models are prepared which use inputs specific to each security. Inputs to these models include factors such as cash flow received, contractual payments required, and various other information related to the underlying collateral (including current delinquencies), collateral loss severity rates (including loan to values), expected delinquency rates, credit support from other tranches, and prepayment speeds. Stress tests are performed at varying levels of delinquency rates, prepayment speeds and loss severities in order to gauge probable ranges of credit loss. At December 31, 2017 , the fair value of securities on this watch list was $68.0 million compared to $79.6 million at December 31, 2016 . As of December 31, 2017 , the Company had recorded OTTI on certain non-agency mortgage-backed securities, part of the watch list mentioned above, which had an aggregate fair value of $26.2 million . The cumulative credit-related portion of the impairment on these securities, which was recorded in earnings, totaled $14.2 million . The Company does not intend to sell these securities and believes it is not likely that it will be required to sell the securities before the recovery of their amortized cost. The credit-related portion of the loss on these securities was based on the cash flows projected to be received over the estimated life of the securities, discounted to present value, and compared to the current amortized cost bases of the securities. Significant inputs to the cash flow models used to calculate the credit losses on these securities included the following: Significant Inputs Range Prepayment CPR 0% - 25% Projected cumulative default 14% - 50% Credit support 0% - 54% Loss severity 15% - 63% The following table presents a rollforward of the cumulative OTTI credit losses recognized in earnings on all available for sale debt securities. (In thousands) 2017 2016 2015 Cumulative OTTI credit losses at January 1 $ 14,080 $ 14,129 $ 13,734 Credit losses on debt securities for which impairment was not previously recognized 111 — 76 Credit losses on debt securities for which impairment was previously recognized 274 270 407 Increase in expected cash flows that are recognized over remaining life of security (266 ) (319 ) (88 ) Cumulative OTTI credit losses at December 31 $ 14,199 $ 14,080 $ 14,129 Securities with unrealized losses recorded in accumulated other comprehensive income are shown in the table below, along with the length of the impairment period. Less than 12 months 12 months or longer Total (In thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses December 31, 2017 U.S. government and federal agency obligations $ 618,617 $ 4,443 $ — $ — $ 618,617 $ 4,443 Government-sponsored enterprise obligations 286,393 1,712 49,766 217 336,159 1,929 State and municipal obligations 282,843 1,752 49,339 1,002 332,182 2,754 Mortgage and asset-backed securities: Agency mortgage-backed securities 1,320,689 9,433 619,300 14,311 1,939,989 23,744 Non-agency mortgage-backed securities 577,017 2,966 153,813 1,871 730,830 4,837 Asset-backed securities 786,048 3,168 264,295 2,069 1,050,343 5,237 Total mortgage and asset-backed securities 2,683,754 15,567 1,037,408 18,251 3,721,162 33,818 Other debt securities 144,090 727 20,202 451 164,292 1,178 Total $ 4,015,697 $ 24,201 $ 1,156,715 $ 19,921 $ 5,172,412 $ 44,122 December 31, 2016 U.S. government and federal agency obligations $ 349,538 $ 2,823 $ 32,208 $ 3,489 $ 381,746 $ 6,312 Government-sponsored enterprise obligations 190,441 1,576 — — 190,441 1,576 State and municipal obligations 700,779 12,164 15,195 529 715,974 12,693 Mortgage and asset-backed securities: Agency mortgage-backed securities 1,147,416 20,638 2,150 5 1,149,566 20,643 Non-agency mortgage-backed securities 688,131 6,373 34,946 120 723,077 6,493 Asset-backed securities 780,209 5,277 358,778 5,936 1,138,987 11,213 Total mortgage and asset-backed securities 2,615,756 32,288 395,874 6,061 3,011,630 38,349 Other debt securities 179,639 1,986 975 26 180,614 2,012 Total $ 4,036,153 $ 50,837 $ 444,252 $ 10,105 $ 4,480,405 $ 60,942 The total available for sale portfolio consisted of approximately 2,000 individual securities at December 31, 2017 . The portfolio included 635 securities, having an aggregate fair value of $5.2 billion , that were in a loss position at December 31, 2017 , compared to 771 securities, with a fair value of $4.5 billion , at December 31, 2016 . The total amount of unrealized loss on these securities was $44.1 million at December 31, 2017, a decrease of $16.8 million compared to the loss at December 31, 2016. At December 31, 2017 , the fair value of securities in an unrealized loss position for 12 months or longer totaled $ 1.2 billion , or 13.2% of the total portfolio value. The Company’s holdings of state and municipal obligations included gross unrealized losses of $2.8 million at December 31, 2017 . The state and municipal portfolio totaled $1.6 billion at fair value, or 18.4% of total available for sale securities. The portfolio is diversified in order to reduce risk, and the Company has processes and procedures in place to monitor its state and municipal holdings, identify signs of financial distress and, if necessary, exit its positions in a timely manner. The credit ratings (Moody’s rating or equivalent) at December 31, 2017 in the state and municipal bond portfolio are shown in the following table. The average credit quality of the portfolio is Aa2 as rated by Moody’s. % of Portfolio Aaa 6.0 % Aa 76.9 A 16.4 Not rated .7 100.0 % The following table presents proceeds from sales of securities and the components of investment securities gains and losses which have been recognized in earnings. (In thousands) 2017 2016 2015 Proceeds from sales of available for sale securities $ 790,152 $ 2,049 $ 675,870 Proceeds from sales of non-marketable securities 2,228 22,331 13,161 Total proceeds $ 792,380 $ 24,380 $ 689,031 Available for sale: Gains realized on sales $ 10,656 $ 109 $ 2,925 Losses realized on sales (10,297 ) — — Losses realized on called bonds (254 ) — — Gain realized on donation 31,074 — — Other-than-temporary impairment recognized on debt securities (385 ) (270 ) (483 ) Non-marketable: Gains realized on sales 970 4,349 2,516 Losses realized on sales (880 ) (502 ) (40 ) Fair value adjustments, net (5,833 ) (3,739 ) 1,402 Investment securities gains (losses), net $ 25,051 $ (53 ) $ 6,320 Investment securities with a fair value of $3.8 billion and $4.4 billion were pledged at December 31, 2017 and 2016 , respectively, to secure public deposits, securities sold under repurchase agreements, trust funds, and borrowings at the Federal Reserve Bank. Securities pledged under agreements pursuant to which the collateral may be sold or re-pledged by the secured parties approximated $662.5 million , while the remaining securities were pledged under agreements pursuant to which the secured parties may not sell or re-pledge the collateral. Except for obligations of various government-sponsored enterprises such as FNMA, FHLB and FHLMC, no investment in a single issuer exceeds 10% of stockholders’ equity.

Land, Buildings And Equipment

Land, Buildings And Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Land, Buildings And Equipment	Land, Buildings and Equipment Land, buildings and equipment consist of the following at December 31, 2017 and 2016 : (In thousands) 2017 2016 Land $ 94,992 $ 98,221 Buildings and improvements 540,204 530,489 Equipment 216,876 258,030 Total 852,072 886,740 Less accumulated depreciation 516,962 549,035 Net land, buildings and equipment $ 335,110 $ 337,705 Depreciation expense of $29.1 million in 2017 and $30.1 million in both 2016 and 2015 , was included in occupancy expense and equipment expense in the consolidated statements of income. Repairs and maintenance expense of $16.4 million , $16.2 million and $16.3 million for 2017 , 2016 and 2015 , respectively, was included in occupancy expense and equipment expense. There has been no interest expense capitalized on construction projects in the past three years.

Goodwill And Other Intangible A

Goodwill And Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill And Other Intangible Assets	Goodwill and Other Intangible Assets The following table presents information about the Company's intangible assets which have estimable useful lives. December 31, 2017 December 31, 2016 ( In thousands) Gross Carrying Amount Accumulated Amortization Valuation Allowance Net Amount Gross Carrying Amount Accumulated Amortization Valuation Allowance Net Amount Amortizable intangible assets: Core deposit premium $ 31,270 $ (28,305 ) $ — $ 2,965 $ 31,270 $ (27,429 ) $ — $ 3,841 Mortgage servicing rights 7,906 (3,244 ) (9 ) 4,653 5,672 (2,782 ) (22 ) 2,868 Total $ 39,176 $ (31,549 ) $ (9 ) $ 7,618 $ 36,942 $ (30,211 ) $ (22 ) $ 6,709 The carrying amount of goodwill and its allocation among segments at December 31, 2017 and 2016 is shown in the table below. As a result of ongoing assessments, no impairment of goodwill was recorded in 2017 , 2016 or 2015 . Further, the annual assessment of qualitative factors on January 1, 2018 revealed no likelihood of impairment as of that date. (In thousands) December 31, 2017 December 31, 2016 Consumer segment $ 70,721 $ 70,721 Commercial segment 67,454 67,454 Wealth segment 746 746 Total goodwill $ 138,921 $ 138,921 Changes in the net carrying amount of goodwill and other net intangible assets for the years ended December 31, 2017 and 2016 are shown in the following table. (In thousands) Goodwill Core Deposit Premium Mortgage Servicing Rights Balance at December 31, 2015 $ 138,921 $ 5,031 $ 1,638 Originations — — 1,539 Amortization — (1,190 ) (316 ) Impairment reversal — — 7 Balance at December 31, 2016 138,921 3,841 2,868 Originations — — 2,234 Amortization — (876 ) (462 ) Impairment reversal — — 13 Balance at December 31, 2017 $ 138,921 $ 2,965 $ 4,653 Mortgage servicing rights (MSRs) are initially recorded at fair value and subsequently amortized over the period of estimated servicing income. They are periodically reviewed for impairment and if impairment is indicated, recorded at fair value. At December 31, 2017 , temporary impairment of $9 thousand had been recognized. Temporary impairment, including impairment recovery, is effected through a change in a valuation allowance. The fair value of the MSRs is based on the present value of expected future cash flows, as further discussed in Note 15 on Fair Value Measurements. Aggregate amortization expense on intangible assets for the years ended December 31, 2017 , 2016 and 2015 was $1.3 million , $1.5 million and $1.8 million , respectively. The following table shows the estimated future amortization expense based on existing asset balances and the interest rate environment as of December 31, 2017 . The Company’s actual amortization expense in any given period may be different from the estimated amounts depending upon the acquisition of intangible assets, changes in mortgage interest rates, prepayment rates and other market conditions. (In thousands) 2018 $ 1,213 2019 1,038 2020 878 2021 753 2022 653

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Deposits	Deposits At December 31, 2017 , the scheduled maturities of total time open and certificates of deposit were as follows: (In thousands) Due in 2018 $ 1,414,554 Due in 2019 217,562 Due in 2020 73,192 Due in 2021 41,313 Due in 2022 18,191 Thereafter 2,052 Total $ 1,766,864 The following table shows a detailed breakdown of the maturities of time open and certificates of deposit, by size category, at December 31, 2017 . (In thousands) Certificates of Deposit under $100,000 Other Time Deposits under $100,000 Certificates of Deposit over $100,000 Other Time Deposits over $100,000 Total Due in 3 months or less $ 115,126 $ 24,019 $ 484,168 $ 3,744 $ 627,057 Due in over 3 through 6 months 115,595 26,607 197,173 5,438 344,813 Due in over 6 through 12 months 180,447 36,573 216,459 9,205 442,684 Due in over 12 months 82,789 53,490 205,085 10,946 352,310 Total $ 493,957 $ 140,689 $ 1,102,885 $ 29,333 $ 1,766,864 The aggregate amount of time open and certificates of deposit that exceeded the $250,000 FDIC insurance limit totaled $880.9 million at December 31, 2017 .

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowings	Borrowings The following table sets forth selected information for short-term borrowings (borrowings with an original maturity of less than one year). (Dollars in thousands) Year End Weighted Rate Average Weighted Rate Average Balance Outstanding Maximum Outstanding at any Month End Balance at December 31 Federal funds purchased and repurchase agreements: 2017 .8 % .7 % $ 1,462,387 $ 1,984,071 $ 1,507,138 2016 .4 .3 1,266,093 1,723,905 1,723,905 2015 .2 .1 1,654,860 2,193,197 1,963,552 Short-term borrowings consist primarily of federal funds purchased and securities sold under agreements to repurchase (repurchase agreements), which generally have one day maturities. At December 31, 2017 , $1.3 billion of these borrowings were short-term repurchase agreements comprised of non-insured customer funds, which were secured by a portion of the Company's investment portfolio. Additional information about the securities pledged for repurchase agreements is provided in Note 18 on Resale and Repurchase Agreements. The Bank is a member of the Des Moines FHLB and has access to term financing from the FHLB. These borrowings are secured under a blanket collateral agreement including primarily residential mortgages as well as all unencumbered assets and stock of the borrowing bank. In November 2017, the Bank repaid its remaining borrowings from the FHLB, which totaled $100.0 million . The FHLB also issues letters of credit to secure the Bank's obligations to certain depositors of public funds, which totaled $498.4 million at December 31, 2017 . At December 31, 2017 , the Bank had no outstanding advances from the FHLB, and its remaining outstanding debt, totaling $1.8 million , relates to leasing activities.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income tax expense from operations for the years ended December 31, 2017 , 2016 and 2015 were as follows: (In thousands) Current Deferred Total Year ended December 31, 2017: U.S. federal $ 89,154 $ 12,190 $ 101,344 State and local 7,735 1,427 9,162 Total $ 96,889 $ 13,617 $ 110,506 Year ended December 31, 2016: U.S. federal $ 116,753 $ (2,036 ) $ 114,717 State and local 9,457 (23 ) 9,434 Total $ 126,210 $ (2,059 ) $ 124,151 Year ended December 31, 2015: U.S. federal $ 102,607 $ 7,084 $ 109,691 State and local 6,551 348 6,899 Total $ 109,158 $ 7,432 $ 116,590 The components of income tax (benefit) expense recorded directly to stockholders’ equity for the years ended December 31, 2017 , 2016 and 2015 were as follows: (In thousands) 2017 2016 2015 Unrealized gain (loss) on securities available for sale $ 2,104 $ (13,952 ) $ (19,634 ) Accumulated pension (benefit) loss (184 ) 778 1,478 Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes — (3,390 ) (2,132 ) Income tax (benefit) expense allocated to stockholders’ equity $ 1,920 $ (16,564 ) $ (20,288 ) Significant components of the Company’s deferred tax assets and liabilities at December 31, 2017 and 2016 were as follows: (In thousands) 2017 2016 Deferred tax assets: Loans, principally due to allowance for loan losses $ 40,341 $ 61,233 Equity-based compensation 8,201 12,633 Deferred compensation 5,647 7,998 Private equity investments 5,473 9,667 Accrued expenses 5,245 16,638 Unearned fee income 3,701 3,819 Other 4,430 6,071 Total deferred tax assets 73,038 118,059 Deferred tax liabilities: Equipment lease financing 45,825 71,355 Unrealized gain on securities available for sale 13,603 18,572 Land, buildings and equipment 8,592 10,375 Undistributed earnings of subsidiaries 7,094 23 Intangibles 5,732 9,105 Other 6,569 8,765 Total deferred tax liabilities 87,415 118,195 Net deferred tax liabilities $ (14,377 ) $ (136 ) Management believes it is more likely than not that the results of future operations will generate sufficient taxable income to realize the total deferred tax assets. As a result of the Tax Cuts and Jobs Act enacted on December 22, 2017, the Company revalued its deferred tax assets and liabilities using the highest maximum corporate tax rate of 21% . This change was reported as a reduction of deferred tax expense. The Company also adopted ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting," on January 1, 2017. This adoption requires all excess tax benefits and tax deficiencies arising from share-based award payments to be recognized as income tax expense or benefit in the statements of income, while in previous periods these benefits and deficiencies were recognized in equity. In 2017, net excess tax benefits resulted from share-based award payments. The effects on federal tax expense of both of these items are shown in the reconciliation below. A reconciliation between the expected federal income tax expense using the federal statutory tax rate of 35% and the Company’s actual income tax expense for 2017 , 2016 and 2015 is provided in the table below. The effective tax rate is calculated by dividing income taxes by income before income taxes less the non-controlling interest expense. (In thousands) 2017 2016 2015 Computed “expected” tax expense $ 150,461 $ 139,840 $ 133,112 Increase (decrease) in income taxes resulting from: Tax-exempt interest, net of cost to carry (20,295 ) (20,033 ) (19,083 ) Contribution of appreciated securities (10,864 ) — — Tax reform enactment (6,753 ) — — Share-based award payments (6,613 ) — — State and local income taxes, net of federal tax benefit 5,955 6,132 4,484 Tax deductible dividends on allocated shares held by the Company’s ESOP (966 ) (1,044 ) (1,093 ) Other (419 ) (744 ) (830 ) Total income tax expense $ 110,506 $ 124,151 $ 116,590 The gross amount of unrecognized tax benefits was $1.2 million at both December 31, 2017 and 2016 , and the total amount of unrecognized tax benefits that would impact the effective tax rate, if recognized, was $785 thousand and $798 thousand , respectively. The activity in the accrued liability for unrecognized tax benefits for the years ended December 31, 2017 and 2016 was as follows: (In thousands) 2017 2016 Unrecognized tax benefits at beginning of year $ 1,228 $ 1,278 Gross increases – tax positions in prior period 5 — Gross decreases – tax positions in prior period — (1 ) Gross increases – current-period tax positions 268 269 Lapse of statute of limitations (293 ) (318 ) Unrecognized tax benefits at end of year $ 1,208 $ 1,228 The Company and its subsidiaries are subject to income tax by federal, state and local government taxing authorities. Tax years 2014 through 2017 remain open to examination for U.S. federal income tax as well as income tax in major state taxing jurisdictions.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Employee Benefit Plans	Employee Benefit Plans Employee benefits charged to operating expenses are summarized in the table below. Substantially all of the Company’s employees are covered by a defined contribution (401(k)) plan, under which the Company makes matching contributions. (In thousands) 2017 2016 2015 Payroll taxes $ 24,402 $ 23,210 $ 22,235 Medical plans 25,143 25,497 20,659 401(k) plan 14,244 13,562 12,841 Pension plans 704 987 1,495 Other 2,883 3,214 2,950 Total employee benefits $ 67,376 $ 66,470 $ 60,180 A portion of the Company’s employees are covered by a noncontributory defined benefit pension plan, however, participation in the pension plan is not available to employees hired after June 30, 2003. All participants are fully vested in their benefit payable upon normal retirement date, which is based on years of participation and compensation. Certain key executives also participate in a supplemental executive retirement plan (the CERP) that the Company funds only as retirement benefits are disbursed. The CERP carries no segregated assets. Since January 2011, all benefits accrued under the pension plan have been frozen. However, the accounts continue to accrue interest at a stated annual rate. The CERP continues to provide credits based on hypothetical contributions in excess of those permitted under the 401(k) plan. In the tables presented below, the pension plan and the CERP are presented on a combined basis. Under the Company’s funding policy for the defined benefit pension plan, contributions are made to a trust as necessary to satisfy the statutory minimum required contribution as defined by the Pension Protection Act, which is intended to provide for current service accruals and for any unfunded accrued actuarial liabilities over a reasonable period. To the extent that these requirements are fully covered by assets in the trust, a contribution might not be made in a particular year. No contributions to the defined benefit plan were made in 2016 . The Company made a discretionary contribution of $5.5 million to its defined benefit pension plan in 2017 in order to reduce pension guarantee premiums. The minimum required contribution for 2018 is expected to be zero . The Company does not expect to make any further contributions in 2018 other than the necessary funding contributions to the CERP. Contributions to the CERP were $439 thousand , $21 thousand and $20 thousand during 2017 , 2016 and 2015 , respectively. The following items are components of the net pension cost for the years ended December 31, 2017 , 2016 and 2015 . (In thousands) 2017 2016 2015 Service cost-benefits earned during the year $ 621 $ 500 $ 503 Interest cost on projected benefit obligation 3,826 3,944 4,762 Expected return on plan assets (5,785 ) (5,751 ) (6,092 ) Amortization of prior service cost (271 ) (271 ) (271 ) Amortization of unrecognized net loss 2,313 2,565 2,593 Net periodic pension cost $ 704 $ 987 $ 1,495 The following table sets forth the pension plans’ funded status, using valuation dates of December 31, 2017 and 2016 . (In thousands ) 2017 2016 Change in projected benefit obligation Projected benefit obligation at prior valuation date $ 116,695 $ 117,562 Service cost 621 500 Interest cost 3,826 3,944 Benefits paid (6,780 ) (6,322 ) Actuarial (gain) loss 6,305 1,011 Projected benefit obligation at valuation date 120,667 116,695 Change in plan assets Fair value of plan assets at prior valuation date 99,537 99,325 Actual return on plan assets 9,564 6,513 Employer contributions 5,939 21 Benefits paid (6,780 ) (6,322 ) Fair value of plan assets at valuation date 108,260 99,537 Funded status and net amount recognized at valuation date $ (12,407 ) $ (17,158 ) The accumulated benefit obligation, which represents the liability of a plan using only benefits as of the measurement date, was $120.7 million and $116.7 million for the combined plans on December 31, 2017 and 2016 , respectively. Amounts not yet reflected in net periodic benefit cost and included in accumulated other comprehensive income (loss) at December 31, 2017 and 2016 are shown below, including amounts recognized in other comprehensive income during the periods. All amounts are shown on a pre-tax basis. (In thousands) 2017 2016 Prior service cost $ 1,806 $ 2,077 Accumulated loss (33,499 ) (33,285 ) Accumulated other comprehensive loss (31,693 ) (31,208 ) Cumulative employer contributions in excess of net periodic benefit cost 19,286 14,050 Net amount recognized as an accrued benefit liability on the December 31 balance sheet $ (12,407 ) $ (17,158 ) Net loss arising during period (2,527 ) (248 ) Amortization of net loss 2,313 2,565 Amortization of prior service cost (271 ) (271 ) Total recognized in other comprehensive income $ (485 ) $ 2,046 Total income (expense) recognized in net periodic pension cost and other comprehensive income $ (1,189 ) $ 1,059 The estimated net loss and prior service cost to be amortized from accumulated other comprehensive income into net periodic pension cost in 2018 is $2.1 million . The following assumptions, on a weighted average basis, were used in accounting for the plans. 2017 2016 2015 Determination of benefit obligation at year end: Effective discount rate for benefit obligations 3.57 % 4.05 % 4.15 % Assumed credit on cash balance accounts 5.00 % 5.00 % 5.00 % Determination of net periodic benefit cost for year ended: Effective discount rate for benefit obligations 3.95 % 4.16 % 3.95 % Effective rate for interest on benefit obligations 3.28 % 3.38 % NA Long-term rate of return on assets 6.00 % 6.00 % 6.00 % Assumed credit on cash balance accounts 5.00 % 5.00 % 5.00 % The following table shows the fair values of the Company’s pension plan assets by asset category at December 31, 2017 and 2016 . Information about the valuation techniques and inputs used to measure fair value are provided in Note 15 on Fair Value Measurements. Fair Value Measurements (In thousands) Total Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017 Assets: U.S. government obligations $ 3,719 $ 3,719 $ — $ — Government-sponsored enterprise obligations (a) 1,282 — 1,282 — State and municipal obligations 8,527 — 8,527 — Agency mortgage-backed securities (b) 7,896 — 7,896 — Non-agency mortgage-backed securities 4,891 — 4,891 — Asset-backed securities 3,833 — 3,833 — Corporate bonds (c) 37,457 — 37,457 — Equity securities and mutual funds: (d) Mutual funds 6,979 6,979 — — Common stocks 23,744 23,744 — — International developed markets funds 7,870 7,870 — — Emerging markets funds 2,062 2,062 — — Total $ 108,260 $ 44,374 $ 63,886 $ — December 31, 2016 Assets: U.S. government obligations $ 3,621 $ 3,621 $ — $ — Government-sponsored enterprise obligations (a) 1,215 — 1,215 — State and municipal obligations 9,148 — 9,148 — Agency mortgage-backed securities (b) 4,073 — 4,073 — Non-agency mortgage-backed securities 5,437 — 5,437 — Asset-backed securities 5,275 — 5,275 — Corporate bonds (c) 34,037 — 34,037 — Equity securities and mutual funds: (d) Mutual funds 10,393 10,393 — — Common stocks 20,141 20,141 — — International developed markets funds 5,100 5,100 — — Emerging markets funds 1,097 1,097 — — Total $ 99,537 $ 40,352 $ 59,185 $ — (a) This category represents bonds (excluding mortgage-backed securities) issued by agencies such as the Federal Home Loan Bank, the Federal Home Loan Mortgage Corp and the Federal National Mortgage Association. (b) This category represents mortgage-backed securities issued by the agencies mentioned in (a). (c) This category represents investment grade bonds issued in the U.S., primarily by domestic issuers, representing diverse industries. (d) This category represents investments in individual common stocks and equity funds. These holdings are diversified, largely across the financial services, consumer goods, healthcare, electronic technology and technology services industries. The investment policy of the pension plan is designed for growth in principal, within limits designed to safeguard against significant losses within the portfolio. The policy sets guidelines, which may change from time to time, regarding the types and percentages of investments held. Currently, the policy includes guidelines such as holding bonds rated investment grade or better and prohibiting investment in Company stock. The plan does not utilize derivatives. Management believes there are no significant concentrations of risk within the plan asset portfolio at December 31, 2017 . Under the current policy, the long-term investment target mix for the plan is 35% equity securities and 65% fixed income securities. The Company regularly reviews its policies on investment mix and may make changes depending on economic conditions and perceived investment risk. Effective January 1, 2016, the Company changed the method used to estimate the interest cost component of net periodic pension cost for its defined benefit pension plan. Prior to the change, the interest cost component was estimated by utilizing a single weighted average discount rate derived from the yield curve used to measure the projected benefit obligation. Under the new method, the interest cost component is estimated by applying the specific annual spot rates along the yield curve used in the determination of the projected benefit obligation to the relevant projected cash flows. This change provides a more precise measurement of the interest cost by improving the correlation between projected benefit cash flows and the corresponding spot yield curve rates. The Company accounted for this change prospectively as a change in accounting estimate. The change resulted in a decrease of approximately $900 thousand in the interest cost component of the estimated annual net periodic pension cost for 2016. The assumed overall expected long-term rate of return on pension plan assets used in calculating 2017 pension plan expense was 6.0% . Determination of the plan’s expected rate of return is based upon historical and anticipated returns of the asset classes invested in by the pension plan and the allocation strategy currently in place among those classes. The rate used in plan calculations may be adjusted by management for current trends in the economic environment. The 10-year annualized return for the Company’s pension plan was 6.3% . During 2017 , the plan’s rate of return was 9.6% , compared to 7.2% in 2016 . Returns for any plan year may be affected by changes in the stock market and interest rates. The Company expects to incur pension expense of $761 thousand in 2018 , compared to $704 thousand in 2017 . The Company utilizes mortality tables published by the Society of Actuaries to incorporate mortality assumptions into the measurement of the pension benefit obligation. At December 31, 2017, the Company utilized an updated mortality projection scale and recently finalized mortality tables. In addition, various other assumptions were changed as the result of a recent experience study. The combined effect of all assumption changes decreased the pension benefit obligation on that date by approximately $300 thousand . The following future benefit payments are expected to be paid: (In thousands) 2018 $ 7,133 2019 7,231 2020 7,413 2021 7,534 2022 7,473 2023 - 2027 37,421

Stock-Based Compensation and Di

Stock-Based Compensation and Directors Stock Purchase Plan	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Stock-Based Compensation	Stock-Based Compensation and Directors Stock Purchase Plan* The Company’s stock-based compensation is provided under a stockholder-approved plan which allows for issuance of various types of awards, including stock options, stock appreciation rights, restricted stock and restricted stock units, performance awards and stock-based awards. During the past three years, stock-based compensation has been issued in the form of nonvested stock awards and stock appreciation rights. At December 31, 2017 , 2,776,076 shares remained available for issuance under the plan. The stock-based compensation expense that was charged against income was $12.1 million , $11.5 million and $10.1 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The total income tax benefit recognized in the income statement for share-based compensation arrangements was $4.5 million , $4.3 million and $3.8 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The Company adopted ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting," on January 1, 2017. The Company elected to change its method of accounting for forfeitures, as allowed by this guidance. In 2016 and prior years, accruals of compensation cost were reduced by an estimate of awards not expected to vest and further adjusted when actual forfeitures occurred. In 2017 and subsequent years, forfeitures will be accounted for when they occur and recognized in compensation cost at that time. The effect of this change, which was recognized as a cumulative-effect adjustment on January 1, 2017, increased equity and increased deferred tax assets by approximately $1.3 million . Nonvested Restricted Stock Awards Nonvested stock is awarded to key employees by action of the Company's Compensation and Human Resources Committee and Board of Directors. These awards generally vest after 4 to 7 years of continued employment, but vesting terms may vary according to the specifics of the individual grant agreement. There are restrictions as to transferability, sale, pledging, or assigning, among others, prior to the end of the vesting period. Dividend and voting rights are conferred upon grant of restricted stock awards. A summary of the status of the Company’s nonvested share awards as of December 31, 2017 and changes during the year then ended is presented below. Shares Weighted Average Grant Date Fair Value Nonvested at January 1, 2017 1,461,713 $ 33.02 Granted 263,123 54.56 Vested (442,435 ) 29.41 Forfeited (27,883 ) 39.12 Canceled — — Nonvested at December 31, 2017 1,254,518 $ 38.67 The total fair value (at vest date) of shares vested during 2017 , 2016 and 2015 was $23.8 million , $10.9 million and $6.0 million , respectively. Stock Appreciation Rights Stock appreciation rights (SARs) are granted with exercise prices equal to the market price of the Company’s stock at the date of grant. SARs vest ratably over four years of continuous service and have 10 -year contractual terms. All SARs must be settled in stock under provisions of the plan. A summary of SAR activity during 2017 is presented below. ( Dollars in thousands, except per share data) Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at January 1, 2017 1,390,782 $ 32.89 Granted 173,740 54.79 Forfeited (13,325 ) 42.19 Expired (878 ) 34.75 Exercised (371,033 ) 29.30 Outstanding at December 31, 2017 1,179,286 $ 37.13 6.2 years $ 22,073 Exercisable at December 31, 2017 630,135 $ 32.60 4.6 years $ 14,645 In determining compensation cost, the Black-Scholes option-pricing model is used to estimate the fair value of SARs on date of grant. The Black-Scholes model is a closed-end model that uses various assumptions as shown in the following table. Expected volatility is based on historical volatility of the Company’s stock. The Company uses historical exercise behavior and other factors to estimate the expected term of the SARs, which represents the period of time that the SARs granted are expected to be outstanding. The risk-free rate for the expected term is based on the U.S. Treasury zero coupon spot rates in effect at the time of grant. The per share average fair value and the model assumptions for SARs granted during the past three years are shown in the table below. 2017 2016 2015 Weighted per share average fair value at grant date $11.94 $6.79 $6.55 Assumptions: Dividend yield 1.6 % 2.2 % 2.2 % Volatility 21.1 % 21.2 % 21.3 % Risk-free interest rate 2.4 % 1.8 % 1.8 % Expected term 7.0 years 7.2 years 7.2 years Additional information about stock options and SARs exercised is presented below. (In thousands) 2017 2016 2015 Intrinsic value of options and SARs exercised $ 9,310 $ 8,854 $ 7,541 Cash received from options and SARs exercised $ — $ — $ 1,914 Tax benefit realized from options and SARs exercised $ 2,698 $ 1,781 $ 1,041 As of December 31, 2017 , there was $24.0 million of unrecognized compensation cost related to unvested SARs and stock awards. This cost is expected to be recognized over a weighted average period of approximately 3.0 years. Directors Stock Purchase Plan The Company has a directors stock purchase plan whereby outside directors of the Company and its subsidiaries may elect to use their directors’ fees to purchase Company stock at market value each month end. Remaining shares available for issuance under this plan were 80,377 at December 31, 2017 . In 2017 , 15,873 shares were purchased at an average price of $54.55 , and in 2016 , 21,568 shares were purchased at an average price of $42.50 . * All share and per share amounts in this note have been restated for the 5% common stock dividend distributed in 2017 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income The table below shows the activity and accumulated balances for components of other comprehensive income. The largest component is the unrealized holding gains and losses on available for sale securities. Unrealized gains and losses on debt securities for which an other-than-temporary impairment (OTTI) has been recorded in current earnings are shown separately below. The other component is amortization from other comprehensive income of losses associated with pension benefits, which occurs as the amortization is included in current net periodic benefit cost. Unrealized Gains (Losses) on Securities (1) Pension Loss (2) Total Accumulated Other Comprehensive Income (In thousands) OTTI Other Balance January 1, 2017 $ 2,975 $ 27,328 $ (19,328 ) $ 10,975 Other comprehensive income (loss) before reclassifications 279 36,307 (2,527 ) 34,059 Amounts reclassified from accumulated other comprehensive income 385 (31,433 ) 2,042 (29,006 ) Current period other comprehensive income (loss), before tax 664 4,874 (485 ) 5,053 Income tax (expense) benefit (252 ) (1,852 ) 184 (1,920 ) Current period other comprehensive income (loss), net of tax 412 3,022 (301 ) 3,133 Transfer of unrealized gain on securities for which impairment was not previously recognized 24 (24 ) — — Balance December 31, 2017 $ 3,411 $ 30,326 $ (19,629 ) $ 14,108 Balance January 1, 2016 $ 3,316 $ 49,750 $ (20,596 ) $ 32,470 Other comprehensive loss before reclassifications (820 ) (36,057 ) (248 ) (37,125 ) Amounts reclassified from accumulated other comprehensive income 270 (108 ) 2,294 2,456 Current period other comprehensive income (loss), before tax (550 ) (36,165 ) 2,046 (34,669 ) Income tax (expense) benefit 209 13,743 (778 ) 13,174 Current period other comprehensive income (loss), net of tax (341 ) (22,422 ) 1,268 (21,495 ) Balance December 31, 2016 $ 2,975 $ 27,328 $ (19,328 ) $ 10,975 (1) The pre-tax amounts reclassified from accumulated other comprehensive income are included in "investment securities gains (losses), net" in the consolidated statements of income. (2) The pre-tax amounts reclassified from accumulated other comprehensive income are included in the computation of net periodic pension cost as "amortization of prior service cost" and "amortization of unrecognized net loss" (see Note 9), for inclusion in the consolidated statements of income.

Segments

Segments	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segments	Segments The Company segregates financial information for use in assessing its performance and allocating resources among three operating segments: Consumer, Commercial and Wealth. The Consumer segment includes the consumer portion of the retail branch network (loans, deposits and other personal banking services), indirect and other consumer financing, and consumer debit and credit card loan and fee businesses. Residential mortgage origination, sales and servicing functions are included in this consumer segment, but residential mortgage loans retained by the Company are not considered part of this segment. The Commercial segment provides corporate lending (including the Small Business Banking product line within the branch network), leasing, international services, and business, government deposit, and related commercial cash management services, as well as merchant and commercial bank card products. The Commercial segment also includes the Capital Markets Group, which sells fixed income securities and provides investment safekeeping and bond accounting services. The Wealth segment provides traditional trust and estate planning, advisory and discretionary investment management, and brokerage services. This segment also provides various loan and deposit related services to its private banking customers. The Company’s business line reporting system derives segment information from the internal profitability reporting system used by management to monitor and manage the financial performance of the Company. This information is based on internal management accounting procedures and methods, which have been developed to reflect the underlying economics of the businesses. These methodologies are applied in connection with funds transfer pricing and assignment of overhead costs among segments. Funds transfer pricing was used in the determination of net interest income by assigning a standard cost (credit) for funds used (provided) by assets and liabilities based on their maturity, prepayment and/or repricing characteristics. Income and expense that directly relate to segment operations are recorded in the segment when incurred. Expenses that indirectly support the segments are allocated based on the most appropriate method available. The Company uses a funds transfer pricing method to value funds used (e.g., loans, fixed assets, and cash) and funds provided (e.g., deposits, borrowings, and equity) by the business segments and their components. This process assigns a specific value to each new source or use of funds with a maturity, based on current swap rates, thus determining an interest spread at the time of the transaction. Non-maturity assets and liabilities are valued using weighted average pools. The funds transfer pricing process attempts to remove interest rate risk from valuation, allowing management to compare profitability under various rate environments. The following tables present selected financial information by segment and reconciliations of combined segment totals to consolidated totals. There were no material intersegment revenues between the three segments. Management periodically makes changes to methods of assigning costs and income to its business segments to better reflect operating results. If appropriate, these changes are reflected in prior year information presented below. Segment Income Statement Data (In thousands) Consumer Commercial Wealth Segment Totals Other/Elimination Consolidated Totals Year ended December 31, 2017: Net interest income $ 279,031 $ 328,345 $ 47,264 $ 654,640 $ 79,039 $ 733,679 Provision for loan losses (41,829 ) 205 (41 ) (41,665 ) (3,579 ) (45,244 ) Non-interest income 136,554 194,581 158,175 489,310 (2,706 ) 486,604 Investment securities gains, net — — — — 25,051 25,051 Non-interest expense (290,905 ) (290,874 ) (120,458 ) (702,237 ) (67,447 ) (769,684 ) Income before income taxes $ 82,851 $ 232,257 $ 84,940 $ 400,048 $ 30,358 $ 430,406 Year ended December 31, 2016: Net interest income $ 268,654 $ 311,704 $ 44,113 $ 624,471 $ 55,578 $ 680,049 Provision for loan losses (36,042 ) 4,378 (122 ) (31,786 ) (4,532 ) (36,318 ) Non-interest income 131,988 199,384 144,661 476,033 (1,641 ) 474,392 Investment securities losses, net — — — — (53 ) (53 ) Non-interest expense (282,061 ) (284,432 ) (113,888 ) (680,381 ) (36,684 ) (717,065 ) Income before income taxes $ 82,539 $ 231,034 $ 74,764 $ 388,337 $ 12,668 $ 401,005 Year ended December 31, 2015: Net interest income $ 266,328 $ 296,510 $ 42,653 $ 605,491 $ 28,829 $ 634,320 Provision for loan losses (34,864 ) 1,032 75 (33,757 ) 5,030 (28,727 ) Non-interest income 119,561 194,133 136,374 450,068 (1,929 ) 448,139 Investment securities gains, net — — — — 6,320 6,320 Non-interest expense (273,378 ) (267,343 ) (108,755 ) (649,476 ) (27,011 ) (676,487 ) Income before income taxes $ 77,647 $ 224,332 $ 70,347 $ 372,326 $ 11,239 $ 383,565 The segment activity, as shown above, includes both direct and allocated items. Amounts in the “Other/Elimination” column include activity not related to the segments, such as that relating to administrative functions, the investment securities portfolio, and the effect of certain expense allocations to the segments. The provision for loan losses in this category contains the difference between net loan charge-offs assigned directly to the segments and the recorded provision for loan loss expense. Included in this category’s net interest income are earnings of the investment portfolio, which are not allocated to a segment. Segment Balance Sheet Data (In thousands) Consumer Commercial Wealth Segment Totals Other/Elimination Consolidated Totals Average balances for 2017: Assets $ 2,610,045 $ 8,830,584 $ 1,218,598 $ 12,659,227 $ 12,372,381 $ 25,031,608 Loans, including held for sale 2,471,578 8,635,035 1,209,792 12,316,405 1,312,746 13,629,151 Goodwill and other intangible assets 76,734 68,538 746 146,018 — 146,018 Deposits 10,190,613 8,301,004 2,090,582 20,582,199 12,587 20,594,786 Average balances for 2016: Assets $ 2,673,915 $ 8,267,963 $ 1,116,969 $ 12,058,847 $ 12,497,624 $ 24,556,471 Loans, including held for sale 2,533,528 8,072,528 1,108,211 11,714,267 1,239,221 12,953,488 Goodwill and other intangible assets 75,971 68,848 746 145,565 — 145,565 Deposits 9,956,327 8,243,394 2,084,940 20,284,661 46,252 20,330,913 The above segment balances include only those items directly associated with the segment. The “Other/Elimination” column includes unallocated bank balances not associated with a segment (such as investment securities and federal funds sold), balances relating to certain other administrative and corporate functions, and eliminations between segment and non-segment balances. This column also includes the resulting effect of allocating such items as float, deposit reserve and capital for the purpose of computing the cost or credit for funds used/provided. The Company’s reportable segments are strategic lines of business that offer different products and services. They are managed separately because each line services a specific customer need, requiring different performance measurement analyses and marketing strategies. The performance measurement of the segments is based on the management structure of the Company and is not necessarily comparable with similar information for any other financial institution. The information is also not necessarily indicative of the segments’ financial condition and results of operations if they were independent entities.

Common and Preferred Stock

Common and Preferred Stock	12 Months Ended
	Dec. 31, 2017
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock	Common and Preferred Stock* On December 18, 2017, the Company distributed a 5% stock dividend on its $5 par common stock for the 24th consecutive year. All per common share data in this report has been restated to reflect the stock dividend. The Company applies the two-class method of computing income per share, as nonvested share-based awards that pay nonforfeitable common stock dividends are considered securities which participate in undistributed earnings with common stock. The two-class method requires the calculation of separate income per share amounts for the nonvested share-based awards and for common stock. Income per share attributable to common stock is shown in the following table. Nonvested share-based awards are further discussed in Note 10 on Stock-Based Compensation. Basic income per share is based on the weighted average number of common shares outstanding during the year. Diluted income per share gives effect to all dilutive potential common shares that were outstanding during the year. Presented below is a summary of the components used to calculate basic and diluted income per common share, which have been restated for all stock dividends. (In thousands, except per share data) 2017 2016 2015 Basic income per common share: Net income attributable to Commerce Bancshares, Inc. $ 319,383 $ 275,391 $ 263,730 Less preferred stock dividends 9,000 9,000 9,000 Net income available to common shareholders 310,383 266,391 254,730 Less income allocated to nonvested restricted stock 3,848 3,698 3,548 Net income allocated to common stock $ 306,535 $ 262,693 $ 251,182 Weighted average common shares outstanding 105,555 105,243 108,016 Basic income per common share $ 2.90 $ 2.50 $ 2.33 Diluted income per common share: Net income available to common shareholders $ 310,383 $ 266,391 $ 254,730 Less income allocated to nonvested restricted stock 3,838 3,692 3,541 Net income allocated to common stock $ 306,545 $ 262,699 $ 251,189 Weighted average common shares outstanding 105,555 105,243 108,016 Net effect of the assumed exercise of stock-based awards -- based on the treasury stock method using the average market price for the respective periods 372 281 336 Weighted average diluted common shares outstanding 105,927 105,524 108,352 Diluted income per common share $ 2.89 $ 2.49 $ 2.32 Unexercised stock options and stock appreciation rights of 152 thousand , 99 thousand and 443 thousand were excluded from the computation of diluted income per share for the years ended December 31, 2017 , 2016 and 2015 , respectively, because their inclusion would have been anti-dilutive. The Company has 6,000,000 depositary shares outstanding, representing 6,000 shares of 6.00% Series B Non-Cumulative Perpetual Preferred Stock, par value $1.00 per share, having an aggregate liquidation preference of $150.0 million (“Series B Preferred Stock”). Each depositary share has a liquidation preference of $25 per share. Dividends on the Series B Preferred Stock, if declared, accrue and are payable quarterly, in arrears, at a rate of 6.00%. The Series B Preferred Stock qualifies as Tier 1 capital for the purposes of the regulatory capital calculations. In the event that the Company does not declare and pay dividends on the Series B Preferred Stock for the most recent dividend period, the ability of the Company to declare or pay dividends on, purchase, redeem or otherwise acquire shares of its common stock or any securities of the Company that rank junior to the Series B Preferred Stock is subject to certain restrictions under the terms of the Series B Preferred Stock. The Company entered into accelerated share repurchase programs in 2014 and 2015 for $200.0 million and $100.0 million , respectively. Final settlement of the programs occurred in mid-2015, and a total of 7.9 million shares of common stock were received by the Company under the programs. Shares purchased under these programs were part of the Company's stock repurchase program, as authorized by its Board of Directors. The most recent authorization in October 2015 approved future purchases of 5,000,000 shares of the Company's common stock. At December 31, 2017 , 3,443,523 shares of common stock remained available for purchase under the current authorization. The table below shows activity in the outstanding shares of the Company’s common stock during the past three years. Shares in the table below are presented on an historical basis and have not been restated for the annual 5% stock dividends. Years Ended December 31 (In thousands) 2017 2016 2015 Shares outstanding at January 1 101,461 97,226 96,327 Issuance of stock: Awards and sales under employee and director plans 403 397 435 5% stock dividend 5,078 4,831 4,641 Purchases of treasury stock under accelerated share repurchase programs — — (3,635 ) Other purchases of treasury stock (315 ) (959 ) (535 ) Other (12 ) (34 ) (7 ) Shares outstanding at December 31 106,615 101,461 97,226 * Except as noted in the above table, all share and per share amounts in this note have been restated for the 5% common stock dividend distributed in 2017 .

Regulatory Capital Requirements

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Regulatory Capital Requirements	Regulatory Capital Requirements The Company is subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and additional discretionary actions by regulators that could have a direct material effect on the Company’s financial statements. The regulations require the Company to meet specific capital adequacy guidelines that involve quantitative measures of the Company’s assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. The Company’s capital classification is also subject to qualitative judgments by the regulators about components, risk weightings and other factors. The following tables show the capital amounts and ratios for the Company (on a consolidated basis) and the Bank, together with the minimum capital adequacy and well-capitalized capital requirements, at the last two year ends. Actual Minimum Capital Adequacy Requirement Well-Capitalized Capital Requirement (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio December 31, 2017 Total Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,747,863 14.35 % $ 1,531,996 8.00 % N.A. N.A. Commerce Bank 2,428,789 12.76 1,522,361 8.00 $ 1,902,951 10.00 % Tier I Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,567,264 13.41 % $ 1,148,997 6.00 % N.A. N.A. Commerce Bank 2,268,131 11.92 1,141,771 6.00 $ 1,522,361 8.00 % Tier I Common Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,422,480 12.65 % $ 861,748 4.50 % N.A. N.A. Commerce Bank 2,268,131 11.92 856,328 4.50 $ 1,236,918 6.50 % Tier I Capital (to adjusted quarterly average assets): (Leverage Ratio) Commerce Bancshares, Inc. (consolidated) $ 2,567,264 10.39 % $ 988,653 4.00 % N.A. N.A. Commerce Bank 2,268,131 9.20 986,240 4.00 $ 1,232,800 5.00 % December 31, 2016 Total Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,529,675 13.32 % $ 1,519,578 8.00 % N.A. N.A. Commerce Bank 2,268,845 12.00 1,512,471 8.00 $ 1,890,589 10.00 % Tier I Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,352,154 12.38 % $ 1,139,684 6.00 % N.A. N.A. Commerce Bank 2,111,797 11.17 1,134,353 6.00 $ 1,512,471 8.00 % Tier I Common Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,207,370 11.62 % $ 854,763 4.50 % N.A. N.A. Commerce Bank 2,111,797 11.17 850,765 4.50 $ 1,228,883 6.50 % Tier I Capital (to adjusted quarterly average assets): (Leverage Ratio) Commerce Bancshares, Inc. (consolidated) $ 2,352,154 9.55 % $ 985,698 4.00 % N.A. N.A. Commerce Bank 2,111,797 8.59 983,081 4.00 $ 1,228,851 5.00 % The minimum required ratios for well-capitalized banks (under prompt corrective action provisions) are 6.5% for Tier I common capital, 8.0% for Tier I capital, 10.0% for Total capital and 5.0% for the leverage ratio. At December 31, 2017 and 2016 , the Company met all capital requirements to which it is subject, and the Bank’s capital position exceeded the regulatory definition of well-capitalized.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company uses fair value measurements to record fair value adjustments to certain financial and nonfinancial assets and liabilities and to determine fair value disclosures. Various financial instruments such as available for sale and trading securities, certain non-marketable securities relating to private equity activities, and derivatives are recorded at fair value on a recurring basis. Additionally, from time to time, the Company may be required to record at fair value other assets and liabilities on a nonrecurring basis, such as loans held for sale, mortgage servicing rights and certain other investment securities. These nonrecurring fair value adjustments typically involve lower of cost or fair value accounting, or write-downs of individual assets. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Depending on the nature of the asset or liability, the Company uses various valuation techniques and assumptions when estimating fair value. For accounting disclosure purposes, a three-level valuation hierarchy of fair value measurements has been established. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows: • Level 1 – inputs to the valuation methodology are quoted prices for identical assets or liabilities in active markets. • Level 2 – inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, and inputs that are observable for the assets or liabilities, either directly or indirectly (such as interest rates, yield curves, and prepayment speeds). • Level 3 – inputs to the valuation methodology are unobservable and significant to the fair value. These may be internally developed, using the Company’s best information and assumptions that a market participant would consider. When determining the fair value measurements for assets and liabilities required or permitted to be recorded or disclosed at fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability. When possible, the Company looks to active and observable markets to price identical assets or liabilities. When identical assets and liabilities are not traded in active markets, the Company looks to observable market data for similar assets and liabilities. Nevertheless, certain assets and liabilities are not actively traded in observable markets, and the Company must use alternative valuation techniques to derive an estimated fair value measurement. Instruments Measured at Fair Value on a Recurring Basis The table below presents the carrying values of assets and liabilities measured at fair value on a recurring basis at December 31, 2017 and 2016 . There were no transfers among levels during these years. Fair Value Measurements Using (In thousands) Total Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017 Assets: Residential mortgage loans held for sale $ 15,327 $ — $ 15,327 $ — Available for sale securities: U.S. government and federal agency obligations 917,147 917,147 — — Government-sponsored enterprise obligations 406,363 — 406,363 — State and municipal obligations 1,611,366 — 1,594,350 17,016 Agency mortgage-backed securities 3,040,913 — 3,040,913 — Non-agency mortgage-backed securities 905,793 — 905,793 — Asset-backed securities 1,492,800 — 1,492,800 — Other debt securities 351,060 — 351,060 — Equity securities 48,838 19,864 28,974 — Trading securities 18,269 — 18,269 — Private equity investments 55,752 — — 55,752 Derivatives * 8,349 — 7,723 626 Assets held in trust for deferred compensation plan 12,843 12,843 — — Total assets 8,884,820 949,854 7,861,572 73,394 Liabilities: Derivatives * 8,074 — 7,951 123 Liabilities held in trust for deferred compensation plan 12,843 12,843 — — Total liabilities $ 20,917 $ 12,843 $ 7,951 $ 123 December 31, 2016 Assets: Residential mortgage loans held for sale $ 9,263 $ — $ 9,263 $ — Available for sale securities: U.S. government and federal agency obligations 920,904 920,904 — — Government-sponsored enterprise obligations 449,998 — 449,998 — State and municipal obligations 1,778,214 — 1,761,532 16,682 Agency mortgage-backed securities 2,685,931 — 2,685,931 — Non-agency mortgage-backed securities 1,055,639 — 1,055,639 — Asset-backed securities 2,381,301 — 2,381,301 — Other debt securities 325,953 — 325,953 — Equity securities 51,263 24,967 26,296 — Trading securities 22,225 — 22,225 — Private equity investments 50,820 — — 50,820 Derivatives * 13,566 — 13,146 420 Assets held in trust for deferred compensation plan 10,261 10,261 — — Total assets 9,755,338 956,132 8,731,284 67,922 Liabilities: Derivatives * 13,339 — 13,177 162 Liabilities held in trust for deferred compensation plan 10,261 10,261 — — Total liabilities $ 23,600 $ 10,261 $ 13,177 $ 162 * The fair value of each class of derivative is shown in Note 17. . Valuation methods for instruments measured at fair value on a recurring basis Following is a description of the Company’s valuation methodologies used for instruments measured at fair value on a recurring basis: Residential mortgage loans held for sale The Company originates fixed rate, first lien residential mortgage loans that are intended for sale in the secondary market. Fair value is based on quoted secondary market prices for loans with similar characteristics, which are adjusted to include the embedded servicing value in the loans. This adjustment represents an unobservable input to the valuation but is not considered significant given the relative insensitivity of the valuation to changes in this input. Accordingly, these loan measurements are classified as Level 2. Available for sale investment securities For available for sale securities, changes in fair value, including that portion of other-than-temporary impairment unrelated to credit loss, are recorded in other comprehensive income. As mentioned in Note 3 on Investment Securities, the Company records the credit-related portion of other-than-temporary impairment in current earnings. This portfolio comprises the majority of the assets which the Company records at fair value. Most of the portfolio, which includes government-sponsored enterprise, mortgage-backed and asset-backed securities, are priced utilizing industry-standard models that consider various assumptions, including time value, yield curves, volatility factors, prepayment speeds, default rates, loss severity, current market and contractual prices for the underlying financial instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace, can be derived from observable data, or are supported by observable levels at which transactions are executed in the marketplace. These measurements are classified as Level 2 in the fair value hierarchy. Where quoted prices are available in an active market, the measurements are classified as Level 1. Most of the Level 1 measurements apply to equity securities and U.S. Treasury obligations. The fair values of Level 1 and 2 securities (excluding equity securities) in the available for sale portfolio are prices provided by a third-party pricing service. The prices provided by the third-party pricing service are based on observable market inputs, as described in the sections below. On a quarterly basis, the Company compares a sample of these prices to other independent sources for the same and similar securities. Variances are analyzed, and, if appropriate, additional research is conducted with the third-party pricing service. Based on this research, the pricing service may affirm or revise its quoted price. No significant adjustments have been made to the prices provided by the pricing service. The pricing service also provides documentation on an ongoing basis that includes reference data, inputs and methodology by asset class, which is reviewed to ensure that security placement within the fair value hierarchy is appropriate. Valuation methods and inputs, by class of security: • U.S. government and federal agency obligations U.S. treasury bills, bonds and notes, including inflation-protected securities, are valued using live data from active market makers and inter-dealer brokers. Valuations for stripped coupon and principal issues are derived from yield curves generated from various dealer contacts and live data sources. • Government-sponsored enterprise obligations Government-sponsored enterprise obligations are evaluated using cash flow valuation models. Inputs used are live market data, cash settlements, Treasury market yields, and floating rate indices such as LIBOR, CMT, and Prime. • State and municipal obligations, excluding auction rate securities A yield curve is generated and applied to bond sectors, and individual bond valuations are extrapolated. Inputs used to generate the yield curve are bellwether issue levels, established trading spreads between similar issuers or credits, historical trading spreads over widely accepted market benchmarks, new issue scales, and verified bid information. Bid information is verified by corroborating the data against external sources such as broker-dealers, trustees/paying agents, issuers, or non-affiliated bondholders. • Mortgage and asset-backed securities Collateralized mortgage obligations and other asset-backed securities are valued at the tranche level. For each tranche valuation, the process generates predicted cash flows for the tranche, applies a market based (or benchmark) yield/spread for each tranche, and incorporates deal collateral performance and tranche level attributes to determine tranche-specific spreads to adjust the benchmark yield. Tranche cash flows are generated from new deal files and prepayment/default assumptions. Tranche spreads are based on tranche characteristics such as average life, type, volatility, ratings, underlying collateral and performance, and prevailing market conditions. The appropriate tranche spread is applied to the corresponding benchmark, and the resulting value is used to discount the cash flows to generate an evaluated price. Valuation of agency pass-through securities, typically issued under GNMA, FNMA, FHLMC, and SBA programs, are primarily derived from information from the To Be Announced (TBA) market. This market consists of generic mortgage pools which have not been received for settlement. Snapshots of the TBA market, using live data feeds distributed by multiple electronic platforms, are used in conjunction with other indices to compute a price based on discounted cash flow models. • Other debt securities Other debt securities are valued using active markets and inter-dealer brokers as well as bullet spread scales and option adjusted spreads. The spreads and models use yield curves, terms and conditions of the bonds, and any special features (e.g., call or put options and redemption features). • Equity securities Equity securities are priced using the market prices for each security from the major stock exchanges or other electronic quotation systems. These are generally classified as Level 1 measurements. Stocks which trade infrequently are classified as Level 2. The available for sale portfolio includes certain auction rate securities. The auction process by which the auction rate securities are normally priced has not functioned in recent years, and due to the illiquidity in the market, the fair value of these securities cannot be based on observable market prices. The fair values of these securities are estimated using a discounted cash flows analysis which is discussed more fully in the Level 3 Inputs section of this note. Because many of the inputs significant to the measurement are not observable, these measurements are classified as Level 3 measurements. Trading securities The securities in the Company’s trading portfolio are priced by averaging several broker quotes for similar instruments and are classified as Level 2 measurements. Private equity investments These securities are held by the Company’s private equity subsidiaries and are included in non-marketable investment securities in the consolidated balance sheets. Due to the absence of quoted market prices, valuation of these nonpublic investments requires significant management judgment. These fair value measurements, which are discussed in the Level 3 Inputs section of this note, are classified as Level 3. Derivatives The Company’s derivative instruments include interest rate swaps, foreign exchange forward contracts, and certain credit risk guarantee agreements. When appropriate, the impact of credit standing as well as any potential credit enhancements, such as collateral, has been considered in the fair value measurement. • Valuations for interest rate swaps are derived from a proprietary model whose significant inputs are readily observable market parameters, primarily yield curves used to calculate current exposure. Counterparty credit risk is incorporated into the model and calculated by applying a net credit spread over LIBOR to the swap's total expected exposure over time. The net credit spread is comprised of spreads for both the Company and its counterparty, derived from probability of default and other loss estimate information obtained from a third party credit data provider or from the Company's Credit Department when not otherwise available. The credit risk component is not significant compared to the overall fair value of the swaps. The results of the model are constantly validated through comparison to active trading in the marketplace. Parties to swaps requiring central clearing are required to post collateral (generally in the form of cash or marketable securities) to an authorized clearing agency that holds and monitors the collateral. In January 2017, the Company's clearing counterparty made rule changes to characterize a component of this collateral as a legal settlement of the derivative contract exposure. As a result, this component, known as variation margin, is no longer accounted for separately from the derivative as collateral, but is considered in determining the fair value of the derivative. The fair value measurements of interest rate swaps are classified as Level 2. • Fair value measurements for foreign exchange contracts are derived from a model whose primary inputs are quotations from global market makers and are classified as Level 2. • The Company’s contracts related to credit risk guarantees are valued under a proprietary model which uses unobservable inputs and assumptions about the creditworthiness of the counterparty (generally a Bank customer). Customer credit spreads, which are based on probability of default and other loss estimates, are calculated internally by the Company's Credit Department, as mentioned above, and are based on the Company's internal risk rating for each customer. Because these inputs are significant to the measurements, they are classified as Level 3. • Derivatives relating to residential mortgage loan sale activity include commitments to originate mortgage loans held for sale, forward loan sale contracts, and forward commitments to sell TBA securities. The fair values of loan commitments and sale contracts are estimated using quoted market prices for loans similar to the underlying loans in these instruments. The valuations of loan commitments are further adjusted to include embedded servicing value and the probability of funding. These assumptions are considered Level 3 inputs and are significant to the loan commitment valuation; accordingly, the measurement of loan commitments is classified as Level 3. The fair value measurement of TBA contracts is based on security prices published on trading platforms and is classified as Level 2. Assets held in trust Assets held in an outside trust for the Company’s deferred compensation plan consist of investments in mutual funds. The fair value measurements are based on quoted prices in active markets and classified as Level 1. The Company has recorded an asset representing the total investment amount. The Company has also recorded a corresponding liability, representing the Company’s liability to the plan participants. The changes in Level 3 assets and liabilities measured at fair value on a recurring basis are summarized as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (In thousands) State and Municipal Obligations Private Equity Investments Derivatives Total Year ended December 31, 2017: Balance at January 1, 2017 $ 16,682 $ 50,820 $ 258 $ 67,760 Total gains or losses (realized/unrealized): Included in earnings — (5,833 ) 266 (5,567 ) Included in other comprehensive income 882 — — 882 Investment securities called (600 ) — — (600 ) Discount accretion 52 — — 52 Purchases of private equity securities — 13,352 — 13,352 Sale / pay down of private equity securities — (2,621 ) — (2,621 ) Capitalized interest/dividends — 34 — 34 Purchase of risk participation agreement — — 70 70 Sale of risk participation agreement — — (91 ) (91 ) Balance at December 31, 2017 $ 17,016 $ 55,752 $ 503 $ 73,271 Total gains or losses for the year included in earnings attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2017 $ — $ (5,658 ) $ 615 $ (5,043 ) Year ended December 31, 2016: Balance at January 1, 2016 $ 17,195 $ 63,032 $ 69 $ 80,296 Total gains or losses (realized/unrealized): Included in earnings — (3,739 ) 43 (3,696 ) Included in other comprehensive income 583 — — 583 Investment securities called (1,200 ) — — (1,200 ) Discount accretion 104 — — 104 Purchases of private equity securities — 9,906 — 9,906 Sale / pay down of private equity securities — (18,471 ) — (18,471 ) Capitalized interest/dividends — 92 — 92 Purchase of risk participation agreement — — 404 404 Sale of risk participation agreement — — (258 ) (258 ) Balance at December 31, 2016 $ 16,682 $ 50,820 $ 258 $ 67,760 Total gains or losses for the year included in earnings attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2016 $ — $ (5,914 ) $ 306 $ (5,608 ) Gains and losses on the Level 3 assets and liabilities in the table above are reported in the following income categories: (In thousands) Loan Fees and Sales Other Non-Interest Income Investment Securities Gains (Losses), Net Total Year ended December 31, 2017: Total gains or losses included in earnings $ 231 $ 35 $ (5,833 ) $ (5,567 ) Change in unrealized gains or losses relating to assets still held at December 31, 2017 $ 580 $ 35 $ (5,658 ) $ (5,043 ) Year ended December 31, 2016: Total gains or losses included in earnings $ 87 $ (44 ) $ (3,739 ) $ (3,696 ) Change in unrealized gains or losses relating to assets still held at December 31, 2016 $ 350 $ (44 ) $ (5,914 ) $ (5,608 ) Level 3 Inputs As shown above, the Company's significant Level 3 measurements which employ unobservable inputs that are readily quantifiable pertain to auction rate securities (ARS) held by the Bank, investments in portfolio concerns held by the Company's private equity subsidiaries, and held for sale residential mortgage loan commitments. ARS are included in state and municipal securities and totaled $17.0 million at December 31, 2017 , while private equity investments, included in non-marketable securities, totaled $55.8 million . Information about these inputs is presented in the table and discussions below. Quantitative Information about Level 3 Fair Value Measurements Weighted Valuation Technique Unobservable Input Range Average Auction rate securities Discounted cash flow Estimated market recovery period 5 years Estimated market rate 3.1% - 4.5% Private equity investments Market comparable companies EBITDA multiple 4.0 - 6.0 Mortgage loan commitments Discounted cash flow Probability of funding 50.4% - 100.0% 76.0% Embedded servicing value (.3)% - 2.0% 1.1% The fair values of ARS are estimated using a discounted cash flows analysis in which estimated cash flows are based on mandatory interest rates paid under failing auctions and projected over an estimated market recovery period. Under normal conditions, ARS traded in weekly auctions and were considered liquid investments. The Company's estimate of when these auctions might resume is highly judgmental and subject to variation depending on current and projected market conditions. Few auctions of these securities have been successful in recent years, and most secondary transactions have been privately arranged. Estimated cash flows during the period over which the Company expects to hold the securities are discounted at an estimated market rate. These securities are comprised of bonds issued by various states and municipalities for healthcare and student lending purposes, and market rates are derived for each type. Market rates are calculated at each valuation date using a LIBOR or Treasury based rate plus spreads representing adjustments for liquidity premium and nonperformance risk. The spreads are developed internally by employees in the Company's bond department. An increase in the holding period alone would result in a higher fair value measurement, while an increase in the estimated market rate (the discount rate) alone would result in a lower fair value measurement. The valuation of the ARS portfolio is reviewed on a quarterly basis by the Company's chief investment officers. The fair values of the Company's private equity investments are based on a determination of fair value of the investee company less preference payments assuming the sale of the investee company. Investee companies are normally non-public entities. The fair value of the investee company is determined by reference to the investee's total earnings before interest, depreciation/amortization, and income taxes (EBITDA) multiplied by an EBITDA factor. EBITDA is normally determined based on a trailing prior period adjusted for specific factors including current economic outlook, investee management, and specific unique circumstances such as sales order information, major customer status, regulatory changes, etc. The EBITDA multiple is based on management's review of published trading multiples for recent private equity transactions and other judgments and is derived for each individual investee. The fair value of the Company's investment (which is usually a partial interest in the investee company) is then calculated based on its ownership percentage in the investee company. On a quarterly basis, these fair value analyses are reviewed by a valuation committee consisting of investment managers and senior Company management. The significant unobservable inputs used in the fair value measurement of the Company’s derivative commitments to originate residential mortgage loans are the percentage of commitments that are actually funded and the mortgage servicing value that is inherent in the underlying loan value. A significant increase in the rate of loans that fund would result in a larger derivative asset or liability. A significant increase in the inherent mortgage servicing value would result in an increase in the derivative asset or a reduction in the derivative liability. The probability of funding and the inherent mortgage servicing values are directly impacted by changes in market rates and will generally move in the same direction as interest rates. Instruments Measured at Fair Value on a Nonrecurring Basis For assets measured at fair value on a nonrecurring basis during 2017 and 2016 , and still held as of December 31, 2017 and 2016 , the following table provides the adjustments to fair value recognized during the respective periods, the level of valuation assumptions used to determine each adjustment, and the carrying value of the related individual assets or portfolios at December 31, 2017 and 2016 . Fair Value Measurements Using (In thousands) Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Gains (Losses) Balance at December 31, 2017 Collateral dependent impaired loans $ 1,236 $ — $ — $ 1,236 $ (617 ) Mortgage servicing rights 4,653 — — 4,653 13 Foreclosed assets — — — — (9 ) Long-lived assets 3,378 — — 3,378 (724 ) Balance at December 31, 2016 Collateral dependent impaired loans $ 1,331 $ — $ — $ 1,331 $ (1,700 ) Mortgage servicing rights 2,868 — — 2,868 7 Foreclosed assets 18 — — 18 (20 ) Long-lived assets 2,408 — — 2,408 (1,054 ) Valuation methods for instruments measured at fair value on a nonrecurring basis Following is a description of the Company’s valuation methodologies used for other financial and nonfinancial instruments measured at fair value on a nonrecurring basis. Collateral dependent impaired loans While the overall loan portfolio is not carried at fair value, the Company periodically records nonrecurring adjustments to the carrying value of loans based on fair value measurements for partial charge-offs of the uncollectible portions of those loans. Nonrecurring adjustments also include certain impairment amounts for collateral dependent loans when establishing the allowance for loan losses. Such amounts are generally based on the fair value of the underlying collateral supporting the loan. In determining the value of real estate collateral, the Company relies on external and internal appraisals of property values depending on the size and complexity of the real estate collateral. The Company maintains a staff of qualified appraisers who also review third party appraisal reports for reasonableness. In the case of non-real estate collateral, reliance is placed on a variety of sources, including external estimates of value and judgments based on the experience and expertise of internal specialists. Values of all loan collateral are regularly reviewed by credit administration. Unobservable inputs to these measurements, which include estimates and judgments often used in conjunction with appraisals, are not readily quantifiable. These measurements are classified as Level 3. Changes in fair value recognized for partial charge-offs of loans and loan impairment reserves on loans held by the Company at December 31, 2017 and 2016 are shown in the table above. Private equity investments and restricted stock These assets are included in non-marketable investment securities in the consolidated balance sheets. They include certain investments in private equity concerns held by the Parent company which are carried at cost, reduced by other-than-temporary impairment. These investments are periodically evaluated for impairment based on their estimated fair value as determined by review of available information, most of which is provided as monthly or quarterly internal financial statements, annual audited financial statements, investee tax returns, and in certain situations, through research into and analysis of the assets and investments held by those private equity concerns. Restricted stock consists of stock issued by the Federal Reserve Bank and FHLB which is held by the bank subsidiary as required for regulatory purposes. Generally, there are restrictions on the sale and/or liquidation of these investments, and they are carried at cost, reduced by other-than-temporary impairment. Fair value measurements for these securities are classified as Level 3. Mortgage servicing rights The Company initially measures its mortgage servicing rights at fair value and amortizes them over the period of estimated net servicing income. They are periodically assessed for impairment based on fair value at the reporting date. Mortgage servicing rights do not trade in an active market with readily observable prices. Accordingly, the fair value is estimated based on a valuation model which calculates the present value of estimated future net servicing income. The model incorporates assumptions that market participants use in estimating future net servicing income, including estimates of prepayment speeds, market discount rates, cost to service, float earnings rates, and other ancillary income, including late fees. The fair value measurements are classified as Level 3. Foreclosed assets Foreclosed assets consist of loan collateral which has been repossessed through foreclosure. This collateral is comprised of commercial and residential real estate and other non-real estate property, including auto, marine and recreational vehicles. Foreclosed assets are initially recorded as held for sale at the lower of the loan balance or fair value of the collateral less estimated selling costs. Subsequent to foreclosure, valuations are updated periodically, and the assets may be marked down further, reflecting a new cost basis. Fair value measurements may be based upon appraisals, third-party price opinions, or internally developed pricing methods. These measurements are classified as Level 3. Long-lived assets When investments in branch facilities and various office buildings are determined to be impaired, their carrying values are written down to estimated fair value, or estimated fair value less cost to sell if the property is held for sale. Fair value is estimated in a process which considers current local commercial real estate market conditions and the judgment of the sales agent and often involves obtaining third party appraisals from certified real estate appraisers. The carrying amounts of these real estate holdings are regularly monitored by real estate professionals employed by the Company. These fair value measurements are classified as Level 3. Unobservable inputs to these measurements, which include estimates and judgments often used in conjunction with appraisals, are not readily quantifiable.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Of Financial Instruments	Fair Value of Financial Instruments The carrying amounts and estimated fair values of financial instruments held by the Company, in addition to a discussion of the methods used and assumptions made in computing those estimates, are set forth below. Loans The fair values of loans are estimated by discounting the expected future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining terms. This method of estimating fair value does not incorporate the exit-price concept of fair value prescribed by ASC 820 “Fair Value Measurements and Disclosures”. Future cash flows for each individual loan are modeled using current rates and all contractual features, while adjusting for optionality such as prepayments. Loans with potential optionality are modeled under a multiple-rate path process. Each loan's expected future cash flows are discounted using the LIBOR/swap curve plus an appropriate spread. For business, construction and business real estate loans, internally-developed pricing spreads based on loan type, term and credit score are utilized. The spread for personal real estate loans is generally based on newly originated loans with similar characteristics. For consumer loans, the spread is calculated at loan origination as part of the Bank's funds transfer pricing process, which is indicative of individual borrower creditworthiness. All consumer credit card loans are discounted at the same spread, depending on whether the rate is variable or fixed. Loans Held for Sale, Investment Securities and Derivative Instruments Detailed descriptions of the fair value measurements of these instruments are provided in Note 15 on Fair Value Measurements. Federal Funds Purchased and Sold, Interest Earning Deposits With Banks and Cash and Due From Banks The carrying amounts of federal funds purchased and sold, interest earning deposits with banks, and cash and due from banks approximates fair value, as these instruments are payable on demand or mature overnight. Securities Purchased/Sold under Agreements to Resell/Repurchase The fair values of these investments and borrowings are estimated by discounting contractual cash flows using an estimate of the current market rate for similar instruments. Deposits The fair value of deposits with no stated maturity is equal to the amount payable on demand. Such deposits include savings and interest and non-interest bearing demand deposits. These fair value estimates do not recognize any benefit the Company receives as a result of being able to administer, or control, the pricing of these accounts. Because they are payable on demand, they are classified as Level 1 in the fair value hierarchy. The fair value of time open and certificates of deposit is based on the discounted value of cash flows, taking early withdrawal optionality into account. Discount rates are based on the Company’s approximate cost of obtaining similar maturity funding in the market. Their fair value measurement is classified as Level 3. Other Borrowings The fair value of other borrowings, which consists mainly of long-term debt, is estimated by discounting contractual cash flows using an estimate of the current market rate for similar instruments. The estimated fair values of the Company’s financial instruments are as follows: Fair Value Hierarchy Level 2017 2016 (In thousands) Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Financial Assets Loans: Business Level 3 $ 4,958,554 $ 4,971,401 $ 4,776,365 $ 4,787,469 Real estate - construction and land Level 3 968,820 979,389 791,236 800,426 Real estate - business Level 3 2,697,452 2,702,598 2,643,374 2,658,093 Real estate - personal Level 3 2,062,787 2,060,443 2,010,397 2,005,227 Consumer Level 3 2,104,487 2,074,129 1,990,801 1,974,784 Revolving home equity Level 3 400,587 400,333 413,634 414,499 Consumer credit card Level 3 783,864 798,093 776,465 794,856 Overdrafts Level 3 7,123 7,123 10,464 10,464 Loans held for sale Level 2 21,398 21,398 14,456 14,456 Investment securities: Available for sale Level 1 937,011 937,011 945,871 945,871 Available for sale Level 2 7,820,253 7,820,253 8,686,650 8,686,650 Available for sale Level 3 17,016 17,016 16,682 16,682 Trading Level 2 18,269 18,269 22,225 22,225 Non-marketable Level 3 100,758 100,758 99,558 99,558 Federal funds sold Level 1 42,775 42,775 15,470 15,470 Securities purchased under agreements to resell Level 3 700,000 695,194 725,000 728,179 Interest earning deposits with banks Level 1 30,631 30,631 272,275 272,275 Cash and due from banks Level 1 438,439 438,439 494,690 494,690 Derivative instruments Level 2 7,723 7,723 13,146 13,146 Derivative instruments Level 3 626 626 420 420 Assets held in trust for deferred compensation plan Level 1 12,843 12,843 10,261 10,261 Financial Liabilities Non-interest bearing deposits Level 1 $ 7,158,962 $ 7,158,962 $ 7,429,398 $ 7,429,398 Savings, interest checking and money market deposits Level 1 11,499,620 11,499,620 11,430,789 11,430,789 Time open and certificates of deposit Level 3 1,766,864 1,768,780 2,240,908 2,235,218 Federal funds purchased Level 1 202,370 202,370 52,840 52,840 Securities sold under agreements to repurchase Level 3 1,304,768 1,305,375 1,671,065 1,671,227 Other borrowings Level 3 1,758 1,758 102,049 104,298 Derivative instruments Level 2 7,951 7,951 13,177 13,177 Derivative instruments Level 3 123 123 162 162 Liabilities held in trust for deferred compensation plan Level 1 12,843 12,843 10,261 10,261 Off-Balance Sheet Financial Instruments The fair value of letters of credit and commitments to extend credit is based on the fees currently charged to enter into similar agreements. The aggregate of these fees is not material. These instruments are also referenced in Note 19 on Commitments, Contingencies and Guarantees. Limitations Fair value estimates are made at a specific point in time based on relevant market information. They do not reflect any premium or discount that could result from offering for sale at one time the Company’s entire holdings of a particular financial instrument. Because no market exists for many of the Company’s financial instruments, fair value estimates are based on judgments regarding future expected loss experience, risk characteristics and economic conditions. These estimates are subjective, involve uncertainties and cannot be determined with precision. Changes in assumptions could significantly affect the estimates.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instrument Detail [Abstract]
Derivative Instruments	Derivative Instruments The notional amounts of the Company’s derivative instruments are shown in the table below. These contractual amounts, along with other terms of the derivative, are used to determine amounts to be exchanged between counterparties and are not a measure of loss exposure. The Company's derivative instruments are accounted for as free-standing derivatives, and changes in their fair value are recorded in current earnings. December 31 (In thousands) 2017 2016 Interest rate swaps $ 1,741,412 $ 1,685,099 Interest rate caps 31,776 59,379 Credit risk participation agreements 133,488 121,514 Foreign exchange contracts 11,826 4,046 Mortgage loan commitments 17,110 12,429 Mortgage loan forward sale contracts 2,566 6,626 Forward TBA contracts 25,000 15,000 Total notional amount $ 1,963,178 $ 1,904,093 The largest group of notional amounts relate to interest rate swap contracts sold to commercial customers who wish to modify their interest rate sensitivity. The customers are engaged in a variety of businesses, including real estate, manufacturing, retail product distribution, education, and retirement communities. These customer swaps are offset by matching contracts purchased by the Company from other financial dealer institutions. Contracts with dealers that require central clearing are novated to a clearing agency who becomes the Company's counterparty. Because of the matching terms of the offsetting contracts, in addition to collateral provisions which mitigate the impact of non-performance risk, changes in fair value subsequent to initial recognition have a minimal effect on earnings. Many of the Company’s interest rate swap arrangements with large financial institutions contain contingent features relating to debt ratings or capitalization levels. Under these provisions, if the Company’s debt rating falls below investment grade or if the Company ceases to be “well-capitalized” under risk-based capital guidelines, certain counterparties can require immediate and ongoing collateralization on interest rate swaps in net liability positions, or can require instant settlement of the contracts. The Company maintains debt ratings and capital well above these minimum requirements. The Company’s foreign exchange activity involves the purchase and sale of forward foreign exchange contracts, which are commitments to purchase or deliver a specified amount of foreign currency at a specific future date. This activity enables customers involved in international business to hedge their exposure to foreign currency exchange rate fluctuations. The Company minimizes its related exposure arising from these customer transactions with offsetting contracts for the same currency and time frame. Risk arises from changes in the currency exchange rate and from the potential for counterparty nonperformance. These risks are controlled by adherence to a foreign exchange trading policy which contains control limits on currency amounts, open positions, maturities and losses, and procedures for approvals, record-keeping, monitoring and reporting. Hedge accounting has not been applied to these foreign exchange activities. Credit risk participation agreements arise when the Company contracts, as a guarantor or beneficiary, with other financial institutions to share credit risk associated with certain interest rate swaps. The Company’s risks and responsibilities as guarantor are further discussed in Note 19 on Commitments, Contingencies and Guarantees. Under its program to sell residential mortgage loans in the secondary market, the Company designates certain newly-originated residential mortgage loans as held for sale. Derivative instruments arising from this activity include mortgage loan commitments and forward loan sale contracts. Changes in the fair values of the loan commitments and funded loans prior to sale that are due to changes in interest rates are economically hedged with forward contracts to sell residential mortgage-backed securities in the to-be-announced (TBA) market. These forward TBA contracts are also considered to be derivatives and are settled in cash at the security settlement date. The fair values of the Company’s derivative instruments are shown in the table below. Information about the valuation methods used to measure fair value is provided in Note 15 on Fair Value Measurements. Derivative instruments with a positive fair value (asset derivatives) are reported in other assets in the consolidated balance sheets while derivative instruments with a negative fair value (liability derivatives) are reported in other liabilities in the consolidated balance sheets. As mentioned in Note 15, effective January 2017, certain collateral posted to and from the Company's clearing counterparty has been offset against the fair values of cleared swaps, such that at December 31, 2017 , the positive fair values of cleared swaps were reduced by $4.5 million and the negative fair values of cleared swaps were reduced by $4.3 million , as reflected in the table below. Asset Derivatives Liability Derivatives December 31 December 31 2017 2016 2017 2016 (In thousands ) Fair Value Fair Value Derivative instruments: Interest rate swaps $ 7,674 $ 12,987 $ (7,857 ) $ (12,987 ) Interest rate caps 16 78 (16 ) (78 ) Credit risk participation agreements 46 65 (123 ) (156 ) Foreign exchange contracts 21 66 (40 ) (4 ) Mortgage loan commitments 580 355 — (6 ) Mortgage loan forward sale contracts 8 — (7 ) (63 ) Forward TBA contracts 4 15 (31 ) (45 ) Total $ 8,349 $ 13,566 $ (8,074 ) $ (13,339 ) The effects of derivative instruments on the consolidated statements of income are shown in the table below. Location of Gain or (Loss) Recognized in Income on Derivative Amount of Gain or (Loss) Recognized in Income on Derivative For the Years Ended December 31 (In thousands) 2017 2016 2015 Derivative instruments: Interest rate swaps Other non-interest income $ 1,978 $ 5,927 $ 4,309 Interest rate caps Other non-interest income — — 32 Credit risk participation agreements Other non-interest income 35 (44 ) 57 Foreign exchange contracts: Other non-interest income (80 ) 55 253 Mortgage loan commitments Loan fees and sales 231 87 263 Mortgage loan forward sale contracts Loan fees and sales 64 (63 ) — Forward TBA contracts Loan fees and sales (648 ) 79 82 Total $ 1,580 $ 6,041 $ 4,996 The following table shows the extent to which assets and liabilities relating to derivative instruments have been offset in the consolidated balance sheets. It also provides information about these instruments which are subject to an enforceable master netting arrangement, irrespective of whether they are offset, and the extent to which the instruments could potentially be offset. Also shown is collateral received or pledged in the form of other financial instruments, which is generally cash or marketable securities. The collateral amounts in this table are limited to the outstanding balance of the related asset or liability (after netting is applied); thus amounts of excess collateral are not shown. Most of the derivatives in the following table were transacted under master netting arrangements that contain a conditional right of offset, such as close-out netting, upon default. The Company is party to master netting arrangements with most of its swap derivative counterparties; however, the Company does not offset derivative assets and liabilities under these arrangements on its consolidated balance sheet. Collateral, usually in the form of marketable securities, is exchanged between the Company and dealer bank counterparties and is generally subject to thresholds and transfer minimums. By contract, it may be sold or re-pledged by the secured party until recalled at a subsequent valuation date by the pledging party. For those swap transactions requiring central clearing, the Company posts cash and securities to its clearing agency. Collateral positions are valued daily, and adjustments to amounts received and pledged by the Company are made as appropriate to maintain proper collateralization for these transactions. Swap derivative transactions with customers are generally secured by rights to non-financial collateral, such as real and personal property, which is not shown in the table below. Gross Amounts Not Offset in the Balance Sheet (In thousands) Gross Amount Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments Available for Offset Collateral Received/Pledged Net Amount December 31, 2017 Assets: Derivatives subject to master netting agreements $ 7,726 $ — $ 7,726 $ (233 ) $ (824 ) $ 6,669 Derivatives not subject to master netting agreements 623 — 623 Total derivatives 8,349 — 8,349 Liabilities: Derivatives subject to master netting agreements 7,935 — 7,935 (233 ) (1,570 ) 6,132 Derivatives not subject to master netting agreements 139 — 139 Total derivatives 8,074 — 8,074 December 31, 2016 Assets: Derivatives subject to master netting agreements $ 13,111 $ — $ 13,111 $ (3,391 ) $ — $ 9,720 Derivatives not subject to master netting agreements 455 — 455 Total derivatives 13,566 — 13,566 Liabilities: Derivatives subject to master netting agreements 13,124 — 13,124 (3,391 ) (5,292 ) 4,441 Derivatives not subject to master netting agreements 215 — 215 Total derivatives 13,339 — 13,339

Resale and Repurchase Agreement

Resale and Repurchase Agreements Resale and Repurchase Agreements	12 Months Ended
	Dec. 31, 2017
Offsetting [Abstract]
Resale and Repurchase Agreements [Text Block]	Resale and Repurchase Agreements The following table shows the extent to which assets and liabilities relating to securities purchased under agreements to resell (resale agreements) and securities sold under agreements to repurchase (repurchase agreements) have been offset in the consolidated balance sheets, in addition to the extent to which they could potentially be offset. Also shown is collateral received or pledged, which consists of marketable securities. The collateral amounts in the table are limited to the outstanding balances of the related asset or liability (after netting is applied); thus amounts of excess collateral are not shown. The agreements in the following table were transacted under master netting arrangements that contain a conditional right of offset, such as close-out netting, upon default. Resale and repurchase agreements are agreements to purchase/sell securities subject to an obligation to resell/repurchase the same or similar securities. They are accounted for as collateralized financing transactions, not as sales and purchases of the securities portfolio. The securities collateral accepted or pledged in resale and repurchase agreements with other financial institutions also may be sold or re-pledged by the secured party, but is usually delivered to and held by third party trustees. The Company generally retains custody of securities pledged for repurchase agreements with customers. The Company is party to several agreements commonly known as collateral swaps. These agreements involve the exchange of collateral under simultaneous repurchase and resale agreements with the same financial institution counterparty. These repurchase and resale agreements have the same principal amounts, inception dates, and maturity dates and have been offset against each other in the balance sheet, having met the accounting requirements for this treatment. The collateral swaps totaled $650.0 million at December 31, 2017 and $550.0 million at December 31, 2016 . At December 31, 2017 , the Company had posted collateral of $661.4 million in marketable securities, consisting of agency mortgage-backed bonds and treasuries, and had accepted $661.3 million in investment grade asset-backed, commercial mortgage-backed, and corporate bonds. Gross Amounts Not Offset in the Balance Sheet (In thousands) Gross Amount Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments Available for Offset Securities Collateral Received/Pledged Net Amount December 31, 2017 Total resale agreements, subject to master netting arrangements $ 1,350,000 $ (650,000 ) $ 700,000 $ — $ (700,000 ) $ — Total repurchase agreements, subject to master netting arrangements 1,954,768 (650,000 ) 1,304,768 — (1,304,768 ) — December 31, 2016 Total resale agreements, subject to master netting arrangements $ 1,275,000 $ (550,000 ) $ 725,000 $ — $ (725,000 ) $ — Total repurchase agreements, subject to master netting arrangements 2,221,065 (550,000 ) 1,671,065 — (1,671,065 ) — The table below shows the remaining contractual maturities of repurchase agreements outstanding at December 31, 2017 and 2016, in addition to the various types of marketable securities that have been pledged as collateral for these borrowings. Remaining Contractual Maturity of the Agreements (In thousands) Overnight and continuous Up to 90 days Greater than 90 days Total December 31, 2017 Repurchase agreements, secured by: U.S. government and federal agency obligations $ 271,820 $ 1,731 $ 450,000 $ 723,551 Government-sponsored enterprise obligations 149,111 — — 149,111 Agency mortgage-backed securities 737,975 9,750 200,000 947,725 Asset-backed securities 89,601 30,000 — 119,601 Other debt securities 14,780 — — 14,780 Total repurchase agreements, gross amount recognized $ 1,263,287 $ 41,481 $ 650,000 $ 1,954,768 December 31, 2016 Repurchase agreements, secured by: U.S. government and federal agency obligations $ 294,600 $ — $ 300,000 $ 594,600 Government-sponsored enterprise obligations 147,694 — 3,237 150,931 Agency mortgage-backed securities 693,851 24,380 252,473 970,704 Asset-backed securities 474,830 30,000 — 504,830 Total repurchase agreements, gross amount recognized $ 1,610,975 $ 54,380 $ 555,710 $ 2,221,065

Commitments, Contingencies And

Commitments, Contingencies And Guarantees	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies And Guarantees	Commitments, Contingencies and Guarantees The Company leases certain premises and equipment, all of which were classified as operating leases. The rent expense under such arrangements amounted to $7.3 million , $7.1 million and $6.8 million in 2017 , 2016 and 2015 , respectively. A summary of minimum lease commitments follows: (In thousands) Type of Property Year Ended December 31 Real Property Equipment Total 2018 $ 5,981 $ 215 $ 6,196 2019 4,876 75 4,951 2020 3,861 32 3,893 2021 3,162 14 3,176 2022 2,678 — 2,678 After 13,383 — 13,383 Total minimum lease payments $ 34,277 All leases expire prior to 2052. It is expected that in the normal course of business, leases that expire will be renewed or replaced by leases on other properties; thus, the future minimum lease commitments are not expected to be less than the amounts shown for 2018 . The Company engages in various transactions and commitments with off-balance sheet risk in the normal course of business to meet customer financing needs. The Company uses the same credit policies in making the commitments and conditional obligations described below as it does for on-balance sheet instruments. The following table summarizes these commitments at December 31: (In thousands) 2017 2016 Commitments to extend credit: Credit card $ 5,102,556 $ 4,932,955 Other 5,737,181 5,508,686 Standby letters of credit, net of participations 387,811 391,899 Commercial letters of credit 4,498 2,962 Commitments to extend credit are legally binding agreements to lend to a borrower providing there are no violations of any conditions established in the contract. As many of the commitments are expected to expire without being drawn upon, the total commitment does not necessarily represent future cash requirements. Refer to Note 2 on Loans and Allowance for Loan Losses for further discussion. Commercial letters of credit act as a means of ensuring payment to a seller upon shipment of goods to a buyer. The majority of commercial letters of credit issued are used to settle payments in international trade. Typically, letters of credit require presentation of documents which describe the commercial transaction, evidence shipment, and transfer title. The Company, as a provider of financial services, routinely issues financial guarantees in the form of financial and performance standby letters of credit. Standby letters of credit are contingent commitments issued by the Company generally to guarantee the payment or performance obligation of a customer to a third party. While these represent a potential outlay by the Company, a significant amount of the commitments may expire without being drawn upon. The Company has recourse against the customer for any amount it is required to pay to a third party under a standby letter of credit. The letters of credit are subject to the same credit policies, underwriting standards and approval process as loans made by the Company. Most of the standby letters of credit are secured, and in the event of nonperformance by the customer, the Company has rights to the underlying collateral, which could include commercial real estate, physical plant and property, inventory, receivables, cash and marketable securities. At December 31, 2017 , the Company had recorded a liability in the amount of $2.5 million , representing the carrying value of the guarantee obligations associated with the standby letters of credit. This amount will be accreted into income over the remaining life of the respective commitments. Commitments outstanding under these letters of credit, which represent the maximum potential future payments guaranteed by the Company, were $387.8 million at December 31, 2017 . The Company regularly purchases various state tax credits arising from third-party property redevelopment. These credits are either resold to third parties or retained for use by the Company. During 2017 , purchases and sales of tax credits amounted to $70.9 million and $47.1 million , respectively. At December 31, 2017 , the Company had outstanding purchase commitments totaling $114.9 million that it expects to fund in 2018 . The Company periodically enters into risk participation agreements (RPAs) as a guarantor to other financial institutions, in order to mitigate those institutions’ credit risk associated with interest rate swaps with third parties. The RPA stipulates that, in the event of default by the third party on the interest rate swap, the Company will reimburse a portion of the loss borne by the financial institution. These interest rate swaps are normally collateralized (generally with real property, inventories and equipment) by the third party, which limits the credit risk associated with the Company’s RPAs. The third parties usually have other borrowing relationships with the Company. The Company monitors overall borrower collateral, and at December 31, 2017 , believes sufficient collateral is available to cover potential swap losses. The RPAs are carried at fair value throughout their term, with all changes in fair value, including those due to a change in the third party’s creditworthiness, recorded in current earnings. The terms of the RPAs, which correspond to the terms of the underlying swaps, range from 2 to 11 years. At December 31, 2017 , the fair value of the Company's guarantee liability RPAs was $123 thousand , and the notional amount of the underlying swaps was $84.1 million . The maximum potential future payment guaranteed by the Company cannot be readily estimated and is dependent upon the fair value of the interest rate swaps at the time of default. The Company has various legal proceedings pending at December 31, 2017 , arising in the normal course of business. While some matters pending against the Company specify damages claimed by plaintiffs, others do not seek a specified amount of damages or are at very early stages of the legal process. The Company records a loss accrual for all legal and regulatory matters for which it deems a loss is probable and can be reasonably estimated. Some matters, which are in the early stages, have not yet progressed to the point where a loss amount can be determined to be probable and estimable.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Parties	Related Parties The Company’s Chief Executive Officer, its Vice Chairman, and its President are directors of Tower Properties Company (Tower) and, together with members of their immediate families, beneficially own approximately 66% of the outstanding stock of Tower. At December 31, 2017 , Tower owned 270,646 shares of Company stock. Tower is primarily engaged in the business of owning, developing, leasing and managing real property. Payments from the Company and its affiliates to Tower are summarized below. These payments, with the exception of dividend payments, relate to property management services, including construction oversight, on three Company-owned office buildings and related parking garages in downtown Kansas City. (In thousands) 2017 2016 2015 Leasing agent fees $ 32 $ 101 $ 66 Operation of parking garages 82 184 75 Building management fees 1,954 1,832 1,850 Property construction management fees 146 147 322 Dividends paid on Company stock held by Tower 232 221 210 Total $ 2,446 $ 2,485 $ 2,523 Tower has a $13.5 million line of credit with the Bank which is subject to normal credit terms and has a variable interest rate. The line of credit is collateralized by Company stock and based on collateral value had a maximum borrowing amount of approximately $11.5 million at December 31, 2017 . There were $5.2 million of borrowings under this line during 2017 , and there was no balance outstanding at December 31, 2017 . There were no borrowings outstanding during 2016 , and the maximum borrowings outstanding during 2015 were $1.3 million . There was no balance outstanding at December 31, 2016 or 2015 . Interest paid on these borrowings during the last three years was not significant. Letters of credit may be collateralized under this line of credit; however, there were no letters of credit outstanding during 2017 , 2016 or 2015 , and thus, no fees were received during these periods. From time to time, the Bank extends additional credit to Tower for construction and development projects. No construction loans were outstanding during 2017 , 2016 and 2015 . Tower leases office space in the Kansas City bank headquarters building owned by the Company. Rent paid to the Company totaled $74 thousand in 2017 , $72 thousand in 2016 , and $69 thousand in 2015 , at $15.75 , $15.67 and $15.42 per square foot, respectively. Directors of the Company and their beneficial interests have deposit accounts with the Bank and may be provided with cash management and other banking services, including loans, in the ordinary course of business. Such loans were made on substantially the same terms, including interest rates and collateral, as those prevailing at the time for comparable transactions with other unrelated persons and did not involve more than the normal risk of collectability. As discussed in Note 19 on Commitments, Contingencies, and Guarantees, the Company regularly purchases various state tax credits arising from third-party property redevelopment and resells the credits to third parties. During 2017 , the Company sold state tax credits to its Chief Executive Officer, its Vice Chairman, and its President, in the amount of $694 thousand , $598 thousand , and $67 thousand , respectively, for personal tax planning. During 2016 , the Company sold state tax credits to its Chief Executive Officer, his father (a former Chief Executive Officer), its Vice Chairman, and its President, in the amount of $549 thousand , $191 thousand , $244 thousand , and $72 thousand , respectively. During 2015 , the Company sold state tax credits to its Chief Executive Officer, his father, its Vice Chairman, and its President in the amount of $478 thousand , $40 thousand , $372 thousand , and $65 thousand , respectively. The terms of the sales and the amounts paid were the same as the terms and amounts paid for similar tax credits by persons not related to the Company.

Parent Company Condensed Financ

Parent Company Condensed Financial Statements	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Condensed Financial Statements	Parent Company Condensed Financial Statements Following are the condensed financial statements of Commerce Bancshares, Inc. (Parent only) for the periods indicated: Condensed Balance Sheets December 31 (In thousands) 2017 2016 Assets Investment in consolidated subsidiaries: Bank $ 2,409,098 $ 2,246,060 Non-banks 52,479 51,816 Cash 151,607 51 Securities purchased under agreements to resell — 155,775 Investment securities: Available for sale 53,285 58,051 Non-marketable 655 718 Note receivable due from bank subsidiary 50,000 — Advances to subsidiaries, net of borrowings 14,571 5,053 Income tax benefits 8,279 524 Other assets 19,951 17,716 Total assets $ 2,759,925 $ 2,535,764 Liabilities and stockholders’ equity Pension obligation $ 12,407 $ 17,158 Other liabilities 30,958 22,823 Total liabilities 43,365 39,981 Stockholders’ equity 2,716,560 2,495,783 Total liabilities and stockholders’ equity $ 2,759,925 $ 2,535,764 Condensed Statements of Income For the Years Ended December 31 (In thousands) 2017 2016 2015 Income Dividends received from consolidated bank subsidiary $ 160,002 $ 160,002 $ 160,001 Earnings of consolidated subsidiaries, net of dividends 147,678 118,704 106,636 Interest and dividends on investment securities 2,099 2,364 2,272 Management fees charged to subsidiaries 30,431 30,965 25,713 Investment securities gains 41,717 1,880 — Net interest income on advances and note to subsidiaries 514 21 4 Other 3,346 2,720 1,422 Total income 385,787 316,656 296,048 Expense Salaries and employee benefits 33,714 29,116 22,167 Professional fees 2,036 1,951 1,833 Data processing fees paid to affiliates 3,512 3,226 3,186 Community service 32,093 1,620 991 Other 10,671 9,849 8,278 Total expense 82,026 45,762 36,455 Income tax benefit (15,622 ) (4,497 ) (4,137 ) Net income $ 319,383 $ 275,391 $ 263,730 Condensed Statements of Cash Flows For the Years Ended December 31 (In thousands ) 2017 2016 2015 Operating Activities Net income $ 319,383 $ 275,391 $ 263,730 Adjustments to reconcile net income to net cash provided by operating activities: Earnings of consolidated subsidiaries, net of dividends (147,678 ) (118,704 ) (106,636 ) Other adjustments, net (11,268 ) 9,541 (1,152 ) Net cash provided by operating activities 160,437 166,228 155,942 Investing Activities (Increase) decrease in securities purchased under agreements to resell 155,775 (51,335 ) 57,210 (Increase) decrease in investment in subsidiaries, net 11 4 (6 ) Proceeds from sales of investment securities 11,006 2,949 — Proceeds from maturities/pay downs of investment securities 2,295 4,105 3,516 Purchases of investment securities — — (2,500 ) Note receivable due from bank subsidiary (50,000 ) — — (Increase) decrease in advances to subsidiaries, net (9,518 ) 13,507 1,171 Net purchases of building improvements and equipment (52 ) (3 ) (113 ) Net cash provided by (used in) investing activities 109,517 (30,773 ) 59,278 Financing Activities Purchases of treasury stock (17,771 ) (39,381 ) (23,176 ) Accelerated share repurchase agreements — — (100,000 ) Issuance of stock under equity compensation plans (8 ) (6 ) 1,914 Cash dividends paid on common stock (91,619 ) (87,070 ) (84,961 ) Cash dividends paid on preferred stock (9,000 ) (9,000 ) (9,000 ) Net cash used in financing activities (118,398 ) (135,457 ) (215,223 ) Increase (decrease) in cash 151,556 (2 ) (3 ) Cash at beginning of year 51 53 56 Cash at end of year $ 151,607 $ 51 $ 53 Income tax payments (receipts), net $ (8,991 ) $ (8,958 ) $ 1,278 Dividends paid by the Parent to its shareholders were substantially provided from Bank dividends. The Bank may distribute common dividends without prior regulatory approval, provided that the dividends do not exceed the sum of net income for the current year and retained net income for the preceding two years, subject to maintenance of minimum capital requirements. The Parent charges fees to its subsidiaries for management services provided, which are allocated to the subsidiaries based primarily on total average assets. The Parent makes cash advances to its private equity subsidiaries for general short-term cash flow purposes. Advances may be made to the Parent by its subsidiary bank holding company for temporary investment of idle funds. Interest on such advances is based on market rates. In 2017, the Bank borrowed $50.0 million from the Parent as part of its strategy to reduce FDIC insurance premiums. The note has a rolling 13 month maturity, and the interest rate is a variable rate equal to the one year treasury rate. For the past several years, the Parent has maintained a $20.0 million line of credit for general corporate purposes with the Bank. The line of credit is secured by investment securities. The Parent has not borrowed under this line during the past three years. At December 31, 2017 , the fair value of available for sale investment securities held by the Parent consisted of investments of $48.7 million in common and preferred stock and $4.6 million in non-agency mortgage-backed securities. The Parent’s unrealized net gain in fair value on its investments was $44.5 million at December 31, 2017 . The corresponding net of tax unrealized gain included in the equity category of accumulated other comprehensive income was $27.6 million . Also included in accumulated other comprehensive income was an unrealized net of tax gain in fair value of investment securities held by subsidiaries, which amounted to $6.2 million at December 31, 2017 . During 2017, the Parent contributed appreciated common stock to a charitable foundation and recorded securities gains of $31.1 million and expense of $32.0 million in these transactions. The Parent also sold holdings of the same investment during the fourth quarter of 2017 for a total gain of $10.0 million . The Parent's remaining holdings of this stock, with a fair value of $45.9 million at December 31, 2017, are expected to be redeemed for cash in a third party merger transaction expected to occur in the first six months of 2018. The Company adopted new accounting guidance on January 1, 2018 which reclassified the unrealized gain in fair value on these holdings (net of tax) to retained earnings, as discussed in the Financial Instruments section on page 52.

Summary of Significant Accoun30

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Nature Of Operations	Nature of Operations Commerce Bancshares, Inc. and its subsidiaries (the Company) conducts its principal activities from approximately 330 locations throughout Missouri, Illinois, Kansas, Oklahoma and Colorado. Principal activities include retail and commercial banking, investment management, securities brokerage, mortgage banking, credit related insurance and private equity investment activities.
Basis Of Presentation	Basis of Presentation The Company follows accounting principles generally accepted in the United States of America (GAAP) and reporting practices applicable to the banking industry. The preparation of financial statements under GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and notes. These estimates are based on information available to management at the time the estimates are made. While the consolidated financial statements reflect management’s best estimates and judgments, actual results could differ from those estimates. The consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries (after elimination of all material intercompany balances and transactions). Certain prior year amounts have been reclassified to conform to the current year presentation. Such reclassifications had no effect on net income or total assets. Management has evaluated subsequent events for potential recognition or disclosure through the date these consolidated financial statements were issued. The Company, in the normal course of business, engages in a variety of activities that involve variable interest entities (VIEs). A VIE is a legal entity that lacks equity investors or whose equity investors do not have a controlling financial interest in the entity through their equity investments. However, an enterprise is deemed to have a controlling financial interest and is the primary beneficiary of a VIE if it has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. An enterprise that is the primary beneficiary must consolidate the VIE. The Company’s interests in VIEs are evaluated to determine if the Company is the primary beneficiary both at inception and when there is a change in circumstances that requires a reconsideration. The Company is considered to be the primary beneficiary in a rabbi trust related to a deferred compensation plan offered to certain employees. The assets and liabilities of this trust, which are included in the accompanying consolidated balance sheets, are not significant. The Company also has variable interests in certain entities in which it is not the primary beneficiary. These entities are not consolidated. These interests include affordable housing limited partnership interests, holdings in its investment portfolio of various asset and mortgage-backed bonds that are issued by securitization trusts, and managed discretionary trust assets that are not included in the accompanying consolidated balance sheets.
Cash And Cash Equivalents	Cash and Cash Equivalents In the accompanying consolidated statements of cash flows, cash and cash equivalents include “Cash and due from banks”, “Federal funds sold and short-term securities purchased under agreements to resell”, and “Interest earning deposits with banks” as segregated in the accompanying consolidated balance sheets. Regulations of the Federal Reserve System require cash balances to be maintained at the Federal Reserve Bank, based on certain deposit levels. The minimum reserve requirement for the Bank at December 31, 2017 totaled $126.1 million , while cash held at the Federal Reserve Bank totaled $30.6 million . Additionally, as of December 31, 2017, the Company had $12.5 million in cash collateral on deposit with another financial institution relating to interest rate swap transactions.
Loans And Related Earnings	Loans and Related Earnings Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off are reported at their outstanding principal balances, net of undisbursed loan proceeds, the allowance for loan losses, and any deferred fees and costs on originated loans. Origination fee income received on loans and amounts representing the estimated direct costs of origination are deferred and amortized to interest income over the life of the loan using the interest method. Interest on loans is accrued based upon the principal amount outstanding. Interest income is recognized primarily on the level yield method. Loan and commitment fees, net of costs, are deferred and recognized in income over the term of the loan or commitment as an adjustment of yield. Annual fees charged on credit card loans are capitalized to principal and amortized over 12 months to loan fees and sales. Other credit card fees, such as cash advance fees and late payment fees, are recognized in income as an adjustment of yield when charged to the cardholder’s account.
Non-Accrual Loans	Non-Accrual Loans Loans are placed on non-accrual status when management does not expect to collect payments consistent with acceptable and agreed upon terms of repayment. Business, construction real estate, business real estate, and personal real estate loans that are contractually 90 days past due as to principal and/or interest payments are generally placed on non-accrual, unless they are both well-secured and in the process of collection. Consumer, revolving home equity and credit card loans are exempt under regulatory rules from being classified as non-accrual. When a loan is placed on non-accrual status, any interest previously accrued but not collected is reversed against current income, and the loan is charged off to the extent uncollectible. Principal and interest payments received on non-accrual loans are generally applied to principal. Interest is included in income only after all previous loan charge-offs have been recovered and is recorded only as received. The loan is returned to accrual status only when the borrower has brought all past due principal and interest payments current, and, in the opinion of management, the borrower has demonstrated the ability to make future payments of principal and interest as scheduled. A six month history of sustained payment performance is generally required before reinstatement of accrual status.
Restructured Loans	Restructured Loans A loan is accounted for as a troubled debt restructuring if the Company, for economic or legal reasons related to the borrowers’ financial difficulties, grants a concession to the borrower that it would not otherwise consider. A troubled debt restructuring typically involves (1) modification of terms such as a reduction of the stated interest rate, loan principal, or accrued interest, (2) a loan renewal at a stated interest rate lower than the current market rate for a new loan with similar risk, or (3) debt that was not reaffirmed in bankruptcy. Business, business real estate, construction real estate and personal real estate troubled debt restructurings with impairment charges are placed on non-accrual status. The Company measures the impairment loss of a troubled debt restructuring in the same manner as described below. Troubled debt restructurings which are performing under their contractual terms continue to accrue interest which is recognized in current earnings.
Impaired Loans	Impaired Loans Loans are evaluated regularly by management for impairment. Included in impaired loans are all non-accrual loans, as well as loans that have been classified as troubled debt restructurings. Once a loan has been identified as impaired, impairment is measured based on either the present value of the expected future cash flows at the loan’s initial effective interest rate or the fair value of the collateral if collateral dependent. Factors considered in determining impairment include delinquency status, cash flow analysis, credit analysis, and collateral value and availability.
Loans Held For Sale	Loans Held For Sale Loans held for sale include student loans and certain fixed rate residential mortgage loans. These loans are typically classified as held for sale upon origination based upon management's intent to sell the production of these loans. The student loans are carried at the lower of aggregate cost or fair value, and their fair value is determined based on sale contract prices. The mortgage loans are carried at fair value under the elected fair value option. Their fair value is based on secondary market prices for loans with similar characteristics, including an adjustment for embedded servicing value. Changes in fair value and gains and losses on sales are included in loan fees and sales. Deferred fees and costs related to these loans are not amortized but are recognized as part of the cost basis of the loan at the time it is sold. Interest income related to loans held for sale is accrued based on the principal amount outstanding and the loan's contractual interest rate. Occasionally, other types of loans may be classified as held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains and losses on sales recognized in loan fees and sales.
Allowance/Provision For Loan Losses	Allowance/Provision for Loan Losses The allowance for loan losses is maintained at a level believed to be appropriate by management to provide for probable loan losses inherent in the portfolio as of the balance sheet date, including losses on known or anticipated problem loans as well as for loans which are not currently known to require specific allowances. Management has established a process to determine the amount of the allowance for loan losses which assesses the risks and losses inherent in its portfolio. Business, construction real estate and business real estate loans are normally larger and more complex, and their collection rates are harder to predict. These loans are more likely to be collateral dependent and are allocated a larger reserve, due to their potential volatility. Personal real estate, credit card, consumer and revolving home equity loans are individually smaller and perform in a more homogenous manner, making loss estimates more predictable. Management’s process provides an allowance consisting of a specific allowance component based on certain individually evaluated loans and a general component based on estimates of reserves needed for pools of loans. Loans subject to individual evaluation generally consist of business, construction real estate, business real estate and personal real estate loans on non-accrual status. These impaired loans are evaluated individually for the impairment of repayment potential and collateral adequacy. Other impaired loans identified as performing troubled debt restructurings are collectively evaluated because they have similar risk characteristics. Loans which have not been identified as impaired are segregated by loan type and sub-type and are collectively evaluated. Reserves calculated for these loan pools are estimated using a consistent methodology that considers historical loan loss experience by loan type, loss emergence periods, delinquencies, current economic factors, loan risk ratings and industry concentrations. The Company’s estimate of the allowance for loan losses and the corresponding provision for loan losses is based on various judgments and assumptions made by management. The amount of the allowance for loan losses is influenced by several qualitative factors which include collateral valuation, evaluation of performance and status, current loan portfolio composition and characteristics, trends in delinquencies, portfolio risk ratings, levels of non-performing assets, and prevailing regional and national economic and business conditions. The estimates, appraisals, evaluations, and cash flows utilized by management may be subject to frequent adjustments due to changing economic prospects of borrowers or properties. These estimates are reviewed periodically and adjustments, if necessary, are recorded in the provision for loan losses in the periods in which they become known. Loans, or portions of loans, are charged off to the extent deemed uncollectible. Loan charge-offs reduce the allowance for loan losses, and recoveries of loans previously charged off are added back to the allowance. Business, business real estate, construction real estate and personal real estate loans are generally charged down to estimated collectible balances when they are placed on non-accrual status. Consumer loans and related accrued interest are normally charged down to the fair value of related collateral (or are charged off in full if no collateral) once the loans are more than 120 days delinquent. Credit card loans are charged off against the allowance for loan losses when the receivable is more than 180 days past due. The interest and fee income previously capitalized but not collected on credit card charge-offs is reversed against interest income.
Operating, Direct Financing And Sales Type Leases	Operating, Direct Financing and Sales Type Leases The net investment in direct financing and sales type leases is included in loans on the Company’s consolidated balance sheets and consists of the present values of the sum of the future minimum lease payments and estimated residual value of the leased asset. Revenue consists of interest earned on the net investment and is recognized over the lease term as a constant percentage return thereon. The net investment in operating leases is included in other assets on the Company’s consolidated balance sheets. It is carried at cost, less the amount depreciated to date. Depreciation is recognized, on the straight-line basis, over the lease term to the estimated residual value. Operating lease revenue consists of the contractual lease payments and is recognized over the lease term in other non-interest income. Estimated residual values are established at lease inception utilizing contract terms, past customer experience, and general market data and are reviewed and adjusted, if necessary, on an annual basis.
Investments In Debt And Equity Securities	Investments in Debt and Equity Securities The Company has classified the majority of its investment portfolio as available for sale. From time to time, the Company sells securities and utilizes the proceeds to reduce borrowings, fund loan growth, or modify its interest rate profile. Securities classified as available for sale are carried at fair value. Changes in fair value, excluding certain losses associated with other-than-temporary impairment (OTTI), are reported in other comprehensive income (loss), a component of stockholders’ equity. Securities are periodically evaluated for OTTI in accordance with guidance provided in ASC 320-10-35. For securities with OTTI, the entire loss in fair value is required to be recognized in current earnings if the Company intends to sell the securities or believes it likely that it will be required to sell the security before the anticipated recovery. If neither condition is met, but the Company does not expect to recover the amortized cost basis, the Company determines whether a credit loss has occurred, and the loss is then recognized in current earnings. The noncredit-related portion of the overall loss is reported in other comprehensive income (loss). Gains and losses realized upon sales of securities are calculated using the specific identification method and are included in investment securities gains (losses), net, in the consolidated statements of income. Purchase premiums and discounts are amortized to interest income using a level yield method over the estimated lives of the securities. For mortgage and asset-backed securities, prepayment experience is evaluated quarterly to determine the appropriate estimate of the future rate of prepayment. When a change in a bond's estimated remaining life is necessary, a corresponding adjustment is made in the related amortization of premium or discount accretion. Non-marketable securities include certain private equity investments, consisting of both debt and equity instruments. These securities are carried at fair value in accordance with ASC 946-10-15, with changes in fair value reported in current earnings. In the absence of readily ascertainable market values, fair value is estimated using internally developed models. Changes in fair value and gains and losses from sales are included in investment securities gains (losses), net in the consolidated statements of income. Other non-marketable securities acquired for debt and regulatory purposes are carried at cost and periodically evaluated for other-than-temporary impairment. Trading account securities, which are bought and held principally for the purpose of resale in the near term, are carried at fair value. Gains and losses, both realized and unrealized, are recorded in non-interest income. Purchases and sales of securities are recognized on a trade date basis. A receivable or payable is recognized for pending transaction settlements.
Securities Purchased Under Agreements To Resell And Securities Sold Under Agreements To Repurchase	Securities Purchased under Agreements to Resell and Securities Sold under Agreements to Repurchase Securities purchased under agreements to resell and securities sold under agreements to repurchase are treated as collateralized financing transactions, not as purchases and sales of the underlying securities. The agreements are recorded at the amount of cash advanced or received. The Company periodically enters into securities purchased under agreements to resell with large financial institutions. Securities pledged by the counterparties to secure these agreements are delivered to a third party custodian. Securities sold under agreements to repurchase are a source of funding to the Company and are offered to cash management customers as an automated, collateralized investment account. From time to time, securities sold may also be used by the Bank to obtain additional borrowed funds at favorable rates. These borrowings are secured by a portion of the Company's investment security portfolio and delivered either to the dealer custody account at the FRB or to the applicable counterparty. The fair value of collateral either received from or provided to a counterparty is monitored daily, and additional collateral is obtained, returned, or provided by the Company in order to maintain full collateralization for these transactions. As permitted by current accounting guidance, the Company offsets certain securities purchased under agreements to resell against securities sold under agreements to repurchase in its balance sheet presentation. These agreements are further discussed in Note 18, Resale and Repurchase Agreements.
Land, Buildings And Equipment	Land, Buildings and Equipment Land is stated at cost, and buildings and equipment are stated at cost, including capitalized interest when appropriate, less accumulated depreciation. Depreciation is computed using a straight-line method, utilizing estimated useful lives; generally 30 years for buildings, 10 years for building improvements, and 3 to 10 years for equipment. Leasehold improvements are amortized over the shorter of 10 years or the remaining lease term. Maintenance and repairs are charged to non-interest expense as incurred.
Foreclosed Assets	Foreclosed Assets Foreclosed assets consist of property that has been repossessed and is comprised of commercial and residential real estate and other non-real estate property, including auto and recreational and marine vehicles. The assets are initially recorded at fair value less estimated selling costs, establishing a new cost basis. Initial valuation adjustments are charged to the allowance for loan losses. Fair values are estimated primarily based on appraisals, third-party price opinions, or internally developed pricing models. After initial recognition, fair value estimates are updated periodically. Declines in fair value below cost are recognized through valuation allowances which may be reversed when supported by future increases in fair value. These valuation adjustments, in addition to gains and losses realized on sales and net operating expenses, are recorded in other non-interest expense.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill is not amortized but is assessed for impairment on an annual basis or more frequently in certain circumstances. When testing for goodwill impairment, the Company may initially perform a qualitative assessment. Based on the results of this qualitative assessment, if the Company concludes it is more likely than not that a reporting unit's fair value is less than its carrying amount, a quantitative analysis is performed. Quantitative valuation methodologies include a combination of formulas using current market multiples, based on recent sales of financial institutions within the Company's geographic marketplace. If the fair value of a reporting unit is less than the carrying amount, additional analysis is required to measure the amount of impairment. The Company has not recorded impairment resulting from goodwill impairment tests. However, adverse changes in the economic environment, operations of the reporting unit, or other factors could result in a decline in fair value. Intangible assets that have finite useful lives, such as core deposit intangibles and mortgage servicing rights, are amortized over their estimated useful lives. Core deposit intangibles are amortized over periods of 8 to 14 years, representing their estimated lives, using accelerated methods. Mortgage servicing rights are amortized in proportion to and over the period of estimated net servicing income, considering appropriate prepayment assumptions. Core deposit intangibles are reviewed for impairment whenever events or changes in circumstances indicate their carrying amount may not be recoverable. Impairment is indicated if the sum of the undiscounted estimated future net cash flows is less than the carrying value of the intangible asset. Mortgage servicing rights, while initially recorded at fair value, are subsequently amortized and carried at the lower of the initial capitalized amount (net of accumulated amortization), or estimated fair value. The Company evaluates its mortgage servicing rights for impairment on a quarterly basis, using estimated prepayment speeds of the underlying mortgage loans serviced and stratifications based on the risk characteristics of the underlying loans. A valuation allowance has been established, through a charge to earnings, to the extent the amortized cost exceeds the estimated fair value. However, the Company has not recorded other-than-temporary impairment losses on either of these types of intangible assets.
Income Taxes	Income Taxes Amounts provided for income tax expense are based on income reported for financial statement purposes and do not necessarily represent amounts currently payable under tax laws. Deferred income taxes are provided for temporary differences between the financial reporting bases and income tax bases of the Company’s assets and liabilities, net operating losses, and tax credit carryforwards. Deferred tax assets and liabilities are measured using the enacted tax rates that are expected to apply to taxable income when such assets and liabilities are anticipated to be settled or realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized as tax expense or benefit in the period that includes the enactment date of the change. In determining the amount of deferred tax assets to recognize in the financial statements, the Company evaluates the likelihood of realizing such benefits in future periods. A valuation allowance is established if it is more likely than not that all or some portion of the deferred tax asset will not be realized. The Company recognizes interest and penalties related to income taxes within income tax expense in the consolidated statements of income. The Company and its eligible subsidiaries file a consolidated federal income tax return. State and local income tax returns are filed on a combined, consolidated or separate return basis based upon each jurisdiction’s laws and regulations.
Derivatives	Derivatives While the Company’s interest rate risk management policy permits the use of hedge accounting for derivatives, all of the derivatives held by the Company during the past several years have been accounted for as free-standing instruments. These instruments are carried at fair value, and changes in fair value are recognized in current earnings. They include interest rate swaps and caps, which are offered to customers to assist in managing their risks of adverse changes in interest rates. Each contract between the Company and a customer is offset by a contract between the Company and an institutional counterparty, thus minimizing the Company's exposure to rate changes. The Company also enters into certain contracts, known as credit risk participation agreements, to buy or sell credit protection on specific interest rate swaps. It also purchases and sells forward foreign exchange contracts, either in connection with customer transactions, or for its own trading purposes. In 2015, the Company began an origination and sales program of certain personal real estate mortgages. Derivative instruments under this program include mortgage loan commitments, forward loan sale contracts, and forward contracts to sell certain to-be-announced (TBA) securities. The Company has master netting arrangements with various counterparties but does not offset derivative assets and liabilities under these arrangements in its consolidated balance sheets. However, interest rate swaps that are executed under central clearing requirements are presented on a net basis as mandated by the statutory terms of the Company's contract with its clearing counterparty. Additional information about derivatives held by the Company and valuation methods employed is provided in Note 15, Fair Value Measurements and Note 17, Derivative Instruments.
Pension Plan	Pension Plan The Company’s pension plan is described in Note 9, Employee Benefit Plans. The funded status of the plan is recognized as an asset or liability in the consolidated balance sheets, and changes in that funded status are recognized in the year in which the changes occur through other comprehensive income. Plan assets and benefit obligations are measured as of fiscal year end. The measurement of the projected benefit obligation and pension expense involve actuarial valuation methods and the use of various actuarial and economic assumptions. The Company monitors the assumptions and updates them periodically. Due to the long-term nature of the pension plan obligation, actual results may differ significantly from estimations. Such differences are adjusted over time as the assumptions are replaced by facts and values are recalculated.
Stock-Based Compensation	Stock-Based Compensation The Company’s stock-based employee compensation plan is described in Note 10, Stock-Based Compensation and Directors Stock Purchase Plan. In accordance with the requirements of ASC 718-10-30-3 and 35-2, the Company measures the cost of stock-based compensation based on the grant-date fair value of the award, recognizing the cost over the requisite service period, which is generally the vesting period. The fair value of an option award is estimated using the Black-Scholes option-pricing model while the fair value of a nonvested stock award is the common stock (CBSH) market price. The expense recognized is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occurred, and was included in salaries and employee benefits in the accompanying consolidated statements of income. As further discussed in Note 10, effective January 1, 2017, the Company recognized forfeitures as a reduction to expense only when they have occurred, as allowed under the provisions of ASU 2016-09.
Comprehensive Income	Comprehensive Income Comprehensive income includes all changes in stockholders’ equity during a period, except those resulting from transactions with stockholders. In addition to net income, other components of the Company’s comprehensive income include the after tax effect of changes in net unrealized gain / loss on securities available for sale and changes in net actuarial gain / loss on defined benefit post-retirement plans. Comprehensive income is reported in the accompanying consolidated statements of comprehensive income. See Note 11 for additional information on accumulated other comprehensive income (loss).
Treasury Stock	Treasury Stock Purchases of the Company’s common stock are recorded at cost. Upon re-issuance for acquisitions, exercises of stock-based awards or other corporate purposes, treasury stock is reduced based upon the average cost basis of shares held.
Income Per Share	Income per Share Basic income per share is computed using the weighted average number of common shares outstanding during each year. Diluted income per share includes the effect of all dilutive potential common shares (primarily stock options and stock appreciation rights) outstanding during each year. The Company applies the two-class method of computing income per share. The two-class method is an earnings allocation formula that determines income per share for common stock and for participating securities, according to dividends declared and participation rights in undistributed earnings. The Company’s nonvested stock awards are considered to be a class of participating security. All per share data has been restated to reflect the 5% stock dividend distributed in December 2017 .

Loans And Allowance For Loan 31

Loans And Allowance For Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Loans And Allowance For Loan Losses [Abstract]
Summary Classification Of Held To Maturity Loan Portfolio	Major classifications within the Company’s held for investment loan portfolio at December 31, 2017 and 2016 are as follows: (In thousands) 2017 2016 Commercial: Business $ 4,958,554 $ 4,776,365 Real estate — construction and land 968,820 791,236 Real estate — business 2,697,452 2,643,374 Personal Banking: Real estate — personal 2,062,787 2,010,397 Consumer 2,104,487 1,990,801 Revolving home equity 400,587 413,634 Consumer credit card 783,864 776,465 Overdrafts 7,123 10,464 Total loans $ 13,983,674 $ 13,412,736
Loans To Directors And Executive Officers	Loans to directors and executive officers of the Parent and the Bank, and to their associates, are summarized as follows: (In thousands) Balance at January 1, 2017 $ 62,991 Additions 655,544 Amounts collected (639,920 ) Amounts written off — Balance, December 31, 2017 $ 78,615
Summary Of Activity In The Allowance For Loan Losses	A summary of the activity in the allowance for losses during the previous three years follows: (In thousands) Commercial Personal Banking Total Balance at December 31, 2014 $ 89,622 $ 66,910 $ 156,532 Provision for loan losses (9,319 ) 38,046 28,727 Deductions: Loans charged off 4,057 46,993 51,050 Less recoveries 5,840 11,483 17,323 Net loans charged off (recoveries) (1,783 ) 35,510 33,727 Balance at December 31, 2015 82,086 69,446 151,532 Provision for loan losses 4,898 31,420 36,318 Deductions: Loans charged off 3,258 47,720 50,978 Less recoveries 7,635 11,425 19,060 Net loans charged off (recoveries) (4,377 ) 36,295 31,918 Balance at December 31, 2016 91,361 64,571 155,932 Provision for loan losses 2,327 42,917 45,244 Deductions: Loans charged off 2,538 52,641 55,179 Less recoveries 2,554 10,981 13,535 Net loans charged off (recoveries) (16 ) 41,660 41,644 Balance at December 31, 2017 $ 93,704 $ 65,828 $ 159,532
Allowance For Loan Losses And Related Loan Balance Disaggregated On The Basis Of Impairment Methodology	The following table shows the balance in the allowance for loan losses and the related loan balance at December 31, 2017 and 2016 , disaggregated on the basis of impairment methodology. Impaired loans evaluated under ASC 310-10-35 include loans on non-accrual status which are individually evaluated for impairment and other impaired loans deemed to have similar risk characteristics, which are collectively evaluated. All other loans are collectively evaluated for impairment under ASC 450-20. Impaired Loans All Other Loans (In thousands) Allowance for Loan Losses Loans Outstanding Allowance for Loan Losses Loans Outstanding December 31, 2017 Commercial $ 3,067 $ 92,613 $ 90,637 $ 8,532,213 Personal Banking 1,176 22,182 64,652 5,336,666 Total $ 4,243 $ 114,795 $ 155,289 $ 13,868,879 December 31, 2016 Commercial $ 1,817 $ 44,795 $ 89,544 $ 8,166,180 Personal Banking 1,292 19,737 63,279 5,182,024 Total $ 3,109 $ 64,532 $ 152,823 $ 13,348,204
Investment In Impaired Loans	(In thousands) 2017 2016 Non-accrual loans $ 11,983 $ 14,283 Restructured loans (accruing) 102,812 50,249 Total impaired loans $ 114,795 $ 64,532
Additional Information About Impaired Loans Held	The following table provides additional information about impaired loans held by the Company at December 31, 2017 and 2016 , segregated between loans for which an allowance for credit losses has been provided and loans for which no allowance has been provided. (In thousands) Recorded Investment Unpaid Principal Balance Related Allowance December 31, 2017 With no related allowance recorded: Business $ 5,356 $ 9,000 $ — Real estate – business 1,299 1,303 — Consumer 779 817 — $ 7,434 $ 11,120 $ — With an allowance recorded: Business $ 72,589 $ 73,168 $ 2,455 Real estate – construction and land 837 841 27 Real estate – business 12,532 13,071 585 Real estate – personal 9,126 11,914 532 Consumer 5,388 5,426 67 Revolving home equity 204 204 11 Consumer credit card 6,685 6,685 566 $ 107,361 $ 111,309 $ 4,243 Total $ 114,795 $ 122,429 $ 4,243 December 31, 2016 With no related allowance recorded: Business $ 7,375 $ 10,470 $ — Real estate – construction and land 557 752 — $ 7,932 $ 11,222 $ — With an allowance recorded: Business $ 29,924 $ 31,795 $ 1,318 Real estate – construction and land 69 72 3 Real estate – business 6,870 8,072 496 Real estate – personal 6,394 9,199 642 Consumer 5,281 5,281 57 Revolving home equity 584 584 1 Consumer credit card 7,478 7,478 592 $ 56,600 $ 62,481 $ 3,109 Total $ 64,532 $ 73,703 $ 3,109
Interest Income Recognized On Impaired Loans	The table below shows interest income recognized during the years ended December 31, 2017 , 2016 and 2015 for impaired loans held at the end of each respective period. This interest relates to accruing restructured loans, as discussed previously. Years Ended December 31 (In thousands) 2017 2016 2015 Interest income recognized on impaired loans: Business $ 3,135 $ 1,064 $ 495 Real estate – construction and land 41 2 80 Real estate – business 514 171 122 Real estate – personal 402 152 187 Consumer 307 339 348 Revolving home equity 10 31 20 Consumer credit card 673 722 750 Total $ 5,082 $ 2,481 $ 2,002
Aging Information On Past Due And Nonaccrual Loans	The following table provides aging information on the Company’s past due and accruing loans, in addition to the balances of loans on non-accrual status, at December 31, 2017 and 2016 . (In thousands) Current or Less Than 30 Days Past Due 30 – 89 Days Past Due 90 Days Past Due and Still Accruing Non-accrual Total December 31, 2017 Commercial: Business $ 4,949,148 $ 3,085 $ 374 $ 5,947 $ 4,958,554 Real estate – construction and land 967,321 1,473 21 5 968,820 Real estate – business 2,694,234 482 — 2,736 2,697,452 Personal Banking: Real estate – personal 2,050,787 6,218 3,321 2,461 2,062,787 Consumer 2,067,025 32,674 3,954 834 2,104,487 Revolving home equity 397,349 1,962 1,276 — 400,587 Consumer credit card 764,568 10,115 9,181 — 783,864 Overdrafts 6,840 283 — — 7,123 Total $ 13,897,272 $ 56,292 $ 18,127 $ 11,983 $ 13,983,674 December 31, 2016 Commercial: Business $ 4,763,274 $ 3,735 $ 674 $ 8,682 $ 4,776,365 Real estate – construction and land 789,633 1,039 — 564 791,236 Real estate – business 2,639,586 2,154 — 1,634 2,643,374 Personal Banking: Real estate – personal 1,995,724 9,162 2,108 3,403 2,010,397 Consumer 1,957,358 29,783 3,660 — 1,990,801 Revolving home equity 411,483 1,032 1,119 — 413,634 Consumer credit card 757,443 10,187 8,835 — 776,465 Overdrafts 10,014 450 — — 10,464 Total $ 13,324,515 $ 57,542 $ 16,396 $ 14,283 $ 13,412,736
Total Average Impaired Loans	Total average impaired loans during 2017 and 2016 are shown in the table below. 2017 2016 (In thousands) Commercial Personal Banking Total Commercial Personal Banking Total Average impaired loans: Non-accrual loans $ 9,658 $ 3,989 $ 13,647 $ 17,294 $ 4,135 $ 21,429 Restructured loans (accruing) 49,070 17,539 66,609 32,295 17,058 49,353 Total $ 58,728 $ 21,528 $ 80,256 $ 49,589 $ 21,193 $ 70,782
Credit Quality Of Commercial Loan Portfolio	The following table provides information about the credit quality of the Commercial loan portfolio, using the Company’s internal rating system as an indicator. The internal rating system is a series of grades reflecting management’s risk assessment, based on its analysis of the borrower’s financial condition. The “pass” category consists of a range of loan grades that reflect increasing, though still acceptable, risk. Movement of risk through the various grade levels in the “pass” category is monitored for early identification of credit deterioration. The “special mention” rating is attached to loans where the borrower exhibits material negative financial trends due to borrower specific or systemic conditions that, if left uncorrected, threaten its capacity to meet its debt obligations. The borrower is believed to have sufficient financial flexibility to react to and resolve its negative financial situation. It is a transitional grade that is closely monitored for improvement or deterioration. The “substandard” rating is applied to loans where the borrower exhibits well-defined weaknesses that jeopardize its continued performance and are of a severity that the distinct possibility of default exists. Loans are placed on “non-accrual” when management does not expect to collect payments consistent with acceptable and agreed upon terms of repayment, as discussed in Note 1. Commercial Loans (In thousands) Business Real Estate -Construction Real Estate - Business Total December 31, 2017 Pass $ 4,740,013 $ 955,499 $ 2,593,005 $ 8,288,517 Special mention 59,177 10,614 50,577 120,368 Substandard 153,417 2,702 51,134 207,253 Non-accrual 5,947 5 2,736 8,688 Total $ 4,958,554 $ 968,820 $ 2,697,452 $ 8,624,826 December 31, 2016 Pass $ 4,607,553 $ 788,778 $ 2,543,348 $ 7,939,679 Special mention 116,642 722 45,479 162,843 Substandard 43,488 1,172 52,913 97,573 Non-accrual 8,682 564 1,634 10,880 Total $ 4,776,365 $ 791,236 $ 2,643,374 $ 8,210,975
Summary Of Loans In The Personal Banking Portfolio Percentage Of Balances Outstanding	The credit quality of Personal Banking loans is monitored primarily on the basis of aging/delinquency, and this information is provided in the table in the above section on "Delinquent and non-accrual loans" . In addition, FICO scores are obtained and updated on a quarterly basis for most of the loans in the Personal Banking portfolio. This is a published credit score designed to measure the risk of default by taking into account various factors from a person's financial history. The bank normally obtains a FICO score at the loan's origination and renewal dates, and updates are obtained on a quarterly basis. Excluded from the table below are certain personal real estate loans for which FICO scores are not obtained because the loans are related to commercial activity. These loans totaled $219.2 million at December 31, 2017 and $237.2 million at December 31, 2016 . The table also excludes consumer loans related to the Company's patient healthcare loan program, which totaled $145.0 million at December 31, 2017 and $75.4 million at December 31, 2016 . As the healthcare loans are guaranteed by the hospital, FICO scores are not considered relevant for this program. The personal real estate loans and consumer loans excluded below totaled less than 7% of the Personal Banking portfolio. For the remainder of loans in the Personal Banking portfolio, the table below shows the percentage of balances outstanding at December 31, 2017 and 2016 by FICO score. Personal Banking Loans % of Loan Category Real Estate - Personal Consumer Revolving Home Equity Consumer Credit Card December 31, 2017 FICO score: Under 600 1.3 % 3.3 % 1.1 % 4.7 % 600 – 659 2.1 5.5 1.7 14.4 660 – 719 10.5 17.3 9.5 34.4 720 – 779 25.6 26.8 21.4 26.0 780 and over 60.5 47.1 66.3 20.5 Total 100.0 % 100.0 % 100.0 % 100.0 % December 31, 2016 FICO score: Under 600 1.3 % 3.4 % 1.0 % 4.9 % 600 – 659 2.6 6.4 1.8 15.5 660 – 719 10.4 19.7 9.7 34.9 720 – 779 25.4 26.3 21.1 25.1 780 and over 60.3 44.2 66.4 19.6 Total 100.0 % 100.0 % 100.0 % 100.0 %
Additional Information about Troubled Debt Restructurings [Table Text Block]	Troubled debt restructurings also include certain credit card loans under various debt management and assistance programs. Modifications to credit card loans generally involve removing the available line of credit, placing loans on amortizing status, and lowering the contractual interest rate. The Company also classified certain loans as troubled debt restructurings because they were not reaffirmed by the borrower in bankruptcy proceedings. These loans are comprised of personal real estate, revolving home equity and consumer loans. Interest on these loans is being recognized on an accrual basis, as the borrowers are continuing to make payments. The table below summarizes the troubled debt restructurings outstanding by type of modification, as described above. December 31 (In thousands) 2017 2016 Accruing loans: Non-market interest rates $ 88,588 $ 34,531 Assistance programs 6,685 7,478 Bankruptcy non-affirmation 7,283 7,937 Other 256 303 Non-accrual loans 7,796 8,825 Total restructured loans $ 110,608 $ 59,074
Outstanding Balance Of Loans Classified As Troubled Debt Restructurings	The table below shows the balance of troubled debt restructurings by loan classification at December 31, 2017 , in addition to the period end balances of restructured loans which the Company considers to have been in default at any time during the past twelve months. For purposes of this disclosure, the Company considers "default" to mean 90 days or more past due as to interest or principal. (In thousands) December 31, 2017 Balance 90 days past due at any time during previous 12 months Commercial: Business $ 77,400 $ — Real estate – construction and land 776 — Real estate – business 12,394 — Personal Banking: Real estate – personal 7,760 278 Consumer 5,389 81 Revolving home equity 204 42 Consumer credit card 6,685 630 Total restructured loans $ 110,608 $ 1,031

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investment Securities, At Fair Value	Investment securities, at fair value, consisted of the following at December 31, 2017 and 2016 . (In thousands) 2017 2016 Available for sale: U.S. government and federal agency obligations $ 917,147 $ 920,904 Government-sponsored enterprise obligations 406,363 449,998 State and municipal obligations 1,611,366 1,778,214 Agency mortgage-backed securities 3,040,913 2,685,931 Non-agency mortgage-backed securities 905,793 1,055,639 Asset-backed securities 1,492,800 2,381,301 Other debt securities 351,060 325,953 Equity securities 48,838 51,263 Total available for sale 8,774,280 9,649,203 Trading 18,269 22,225 Non-marketable 100,758 99,558 Total investment securities $ 8,893,307 $ 9,770,986
Summary Of Available For Sale Investment Securities By Maturity Groupings	(Dollars in thousands) Amortized Cost Fair Value Weighted Average Yield U.S. government and federal agency obligations: Within 1 year $ 57,983 $ 58,347 1.71 After 1 but within 5 years 641,114 639,192 1.45 After 5 but within 10 years 149,589 149,927 .43 After 10 years 68,808 69,681 .59 Total U.S. government and federal agency obligations 917,494 917,147 1.24 Government-sponsored enterprise obligations: Within 1 year 215,763 215,434 1.35 After 1 but within 5 years 121,575 121,199 1.93 After 5 but within 10 years 34,983 34,870 2.71 After 10 years 35,945 34,860 3.00 Total government-sponsored enterprise obligations 408,266 406,363 1.79 State and municipal obligations: Within 1 year 164,756 165,638 2.65 After 1 but within 5 years 665,351 670,953 2.21 After 5 but within 10 years 709,248 721,181 2.46 After 10 years 53,352 53,594 3.01 Total state and municipal obligations 1,592,707 1,611,366 2.39 Mortgage and asset-backed securities: Agency mortgage-backed securities 3,046,701 3,040,913 2.62 Non-agency mortgage-backed securities 903,920 905,793 2.54 Asset-backed securities 1,495,380 1,492,800 2.03 Total mortgage and asset-backed securities 5,446,001 5,439,506 2.45 Other debt securities: Within 1 year 10,390 10,389 After 1 but within 5 years 247,181 247,626 After 5 but within 10 years 93,417 93,045 Total other debt securities 350,988 351,060 Equity securities 4,411 48,838 Total available for sale investment securities $ 8,719,867 $ 8,774,280
Available For Sale Securities Unrealized Gains And Losses By Security Type	For securities classified as available for sale, the following table shows the unrealized gains and losses (pre-tax) in accumulated other comprehensive income, by security type. (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value December 31, 2017 U.S. government and federal agency obligations $ 917,494 $ 4,096 $ (4,443 ) $ 917,147 Government-sponsored enterprise obligations 408,266 26 (1,929 ) 406,363 State and municipal obligations 1,592,707 21,413 (2,754 ) 1,611,366 Mortgage and asset-backed securities: Agency mortgage-backed securities 3,046,701 17,956 (23,744 ) 3,040,913 Non-agency mortgage-backed securities 903,920 6,710 (4,837 ) 905,793 Asset-backed securities 1,495,380 2,657 (5,237 ) 1,492,800 Total mortgage and asset-backed securities 5,446,001 27,323 (33,818 ) 5,439,506 Other debt securities 350,988 1,250 (1,178 ) 351,060 Equity securities 4,411 44,427 — 48,838 Total $ 8,719,867 $ 98,535 $ (44,122 ) $ 8,774,280 December 31, 2016 U.S. government and federal agency obligations $ 919,904 $ 7,312 $ (6,312 ) $ 920,904 Government-sponsored enterprise obligations 450,448 1,126 (1,576 ) 449,998 State and municipal obligations 1,778,684 12,223 (12,693 ) 1,778,214 Mortgage and asset-backed securities: Agency mortgage-backed securities 2,674,964 31,610 (20,643 ) 2,685,931 Non-agency mortgage-backed securities 1,054,446 7,686 (6,493 ) 1,055,639 Asset-backed securities 2,389,176 3,338 (11,213 ) 2,381,301 Total mortgage and asset-backed securities 6,118,586 42,634 (38,349 ) 6,122,871 Other debt securities 327,030 935 (2,012 ) 325,953 Equity securities 5,678 45,585 — 51,263 Total $ 9,600,330 $ 109,815 $ (60,942 ) $ 9,649,203
Cash Flow Model Inputs Used To Calculate Credit Losses	The credit-related portion of the loss on these securities was based on the cash flows projected to be received over the estimated life of the securities, discounted to present value, and compared to the current amortized cost bases of the securities. Significant inputs to the cash flow models used to calculate the credit losses on these securities included the following: Significant Inputs Range Prepayment CPR 0% - 25% Projected cumulative default 14% - 50% Credit support 0% - 54% Loss severity 15% - 63%
Changes In Recorded Credit Losses	The following table presents a rollforward of the cumulative OTTI credit losses recognized in earnings on all available for sale debt securities. (In thousands) 2017 2016 2015 Cumulative OTTI credit losses at January 1 $ 14,080 $ 14,129 $ 13,734 Credit losses on debt securities for which impairment was not previously recognized 111 — 76 Credit losses on debt securities for which impairment was previously recognized 274 270 407 Increase in expected cash flows that are recognized over remaining life of security (266 ) (319 ) (88 ) Cumulative OTTI credit losses at December 31 $ 14,199 $ 14,080 $ 14,129
Securities With Unrealized Losses And Length Of Impairment Period	Securities with unrealized losses recorded in accumulated other comprehensive income are shown in the table below, along with the length of the impairment period. Less than 12 months 12 months or longer Total (In thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses December 31, 2017 U.S. government and federal agency obligations $ 618,617 $ 4,443 $ — $ — $ 618,617 $ 4,443 Government-sponsored enterprise obligations 286,393 1,712 49,766 217 336,159 1,929 State and municipal obligations 282,843 1,752 49,339 1,002 332,182 2,754 Mortgage and asset-backed securities: Agency mortgage-backed securities 1,320,689 9,433 619,300 14,311 1,939,989 23,744 Non-agency mortgage-backed securities 577,017 2,966 153,813 1,871 730,830 4,837 Asset-backed securities 786,048 3,168 264,295 2,069 1,050,343 5,237 Total mortgage and asset-backed securities 2,683,754 15,567 1,037,408 18,251 3,721,162 33,818 Other debt securities 144,090 727 20,202 451 164,292 1,178 Total $ 4,015,697 $ 24,201 $ 1,156,715 $ 19,921 $ 5,172,412 $ 44,122 December 31, 2016 U.S. government and federal agency obligations $ 349,538 $ 2,823 $ 32,208 $ 3,489 $ 381,746 $ 6,312 Government-sponsored enterprise obligations 190,441 1,576 — — 190,441 1,576 State and municipal obligations 700,779 12,164 15,195 529 715,974 12,693 Mortgage and asset-backed securities: Agency mortgage-backed securities 1,147,416 20,638 2,150 5 1,149,566 20,643 Non-agency mortgage-backed securities 688,131 6,373 34,946 120 723,077 6,493 Asset-backed securities 780,209 5,277 358,778 5,936 1,138,987 11,213 Total mortgage and asset-backed securities 2,615,756 32,288 395,874 6,061 3,011,630 38,349 Other debt securities 179,639 1,986 975 26 180,614 2,012 Total $ 4,036,153 $ 50,837 $ 444,252 $ 10,105 $ 4,480,405 $ 60,942
State And Municipal Obligations, By State And Economic Sector	The Company’s holdings of state and municipal obligations included gross unrealized losses of $2.8 million at December 31, 2017 . The state and municipal portfolio totaled $1.6 billion at fair value, or 18.4% of total available for sale securities. The portfolio is diversified in order to reduce risk, and the Company has processes and procedures in place to monitor its state and municipal holdings, identify signs of financial distress and, if necessary, exit its positions in a timely manner.
Credit Ratings In State And Municipal Bond Portfolio	The credit ratings (Moody’s rating or equivalent) at December 31, 2017 in the state and municipal bond portfolio are shown in the following table. The average credit quality of the portfolio is Aa2 as rated by Moody’s. % of Portfolio Aaa 6.0 % Aa 76.9 A 16.4 Not rated .7 100.0 %
Proceeds From Sales Of Securities And Components Of Investment Securities Gains And Losses	The following table presents proceeds from sales of securities and the components of investment securities gains and losses which have been recognized in earnings. (In thousands) 2017 2016 2015 Proceeds from sales of available for sale securities $ 790,152 $ 2,049 $ 675,870 Proceeds from sales of non-marketable securities 2,228 22,331 13,161 Total proceeds $ 792,380 $ 24,380 $ 689,031 Available for sale: Gains realized on sales $ 10,656 $ 109 $ 2,925 Losses realized on sales (10,297 ) — — Losses realized on called bonds (254 ) — — Gain realized on donation 31,074 — — Other-than-temporary impairment recognized on debt securities (385 ) (270 ) (483 ) Non-marketable: Gains realized on sales 970 4,349 2,516 Losses realized on sales (880 ) (502 ) (40 ) Fair value adjustments, net (5,833 ) (3,739 ) 1,402 Investment securities gains (losses), net $ 25,051 $ (53 ) $ 6,320

Land, Buildings And Equipment (

Land, Buildings And Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule Of Land, Buildings And Equipment	Land, buildings and equipment consist of the following at December 31, 2017 and 2016 : (In thousands) 2017 2016 Land $ 94,992 $ 98,221 Buildings and improvements 540,204 530,489 Equipment 216,876 258,030 Total 852,072 886,740 Less accumulated depreciation 516,962 549,035 Net land, buildings and equipment $ 335,110 $ 337,705

Goodwill And Other Intangible34

Goodwill And Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule Of Intangible Assets With Estimable Useful Lives	The following table presents information about the Company's intangible assets which have estimable useful lives. December 31, 2017 December 31, 2016 ( In thousands) Gross Carrying Amount Accumulated Amortization Valuation Allowance Net Amount Gross Carrying Amount Accumulated Amortization Valuation Allowance Net Amount Amortizable intangible assets: Core deposit premium $ 31,270 $ (28,305 ) $ — $ 2,965 $ 31,270 $ (27,429 ) $ — $ 3,841 Mortgage servicing rights 7,906 (3,244 ) (9 ) 4,653 5,672 (2,782 ) (22 ) 2,868 Total $ 39,176 $ (31,549 ) $ (9 ) $ 7,618 $ 36,942 $ (30,211 ) $ (22 ) $ 6,709
Schedule Of Goodwill Allocated By Operating Segments	The carrying amount of goodwill and its allocation among segments at December 31, 2017 and 2016 is shown in the table below. As a result of ongoing assessments, no impairment of goodwill was recorded in 2017 , 2016 or 2015 . Further, the annual assessment of qualitative factors on January 1, 2018 revealed no likelihood of impairment as of that date. (In thousands) December 31, 2017 December 31, 2016 Consumer segment $ 70,721 $ 70,721 Commercial segment 67,454 67,454 Wealth segment 746 746 Total goodwill $ 138,921 $ 138,921
Schedule Of Changes In Carrying Amount Of Goodwill And Net Other Intangible Assets	Changes in the net carrying amount of goodwill and other net intangible assets for the years ended December 31, 2017 and 2016 are shown in the following table. (In thousands) Goodwill Core Deposit Premium Mortgage Servicing Rights Balance at December 31, 2015 $ 138,921 $ 5,031 $ 1,638 Originations — — 1,539 Amortization — (1,190 ) (316 ) Impairment reversal — — 7 Balance at December 31, 2016 138,921 3,841 2,868 Originations — — 2,234 Amortization — (876 ) (462 ) Impairment reversal — — 13 Balance at December 31, 2017 $ 138,921 $ 2,965 $ 4,653
Schedule of Estimated Annual Amortization Expense	The following table shows the estimated future amortization expense based on existing asset balances and the interest rate environment as of December 31, 2017 . The Company’s actual amortization expense in any given period may be different from the estimated amounts depending upon the acquisition of intangible assets, changes in mortgage interest rates, prepayment rates and other market conditions. (In thousands) 2018 $ 1,213 2019 1,038 2020 878 2021 753 2022 653

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Scheduled Maturities Of Total Time Open And Certificates Of Deposit	At December 31, 2017 , the scheduled maturities of total time open and certificates of deposit were as follows: (In thousands) Due in 2018 $ 1,414,554 Due in 2019 217,562 Due in 2020 73,192 Due in 2021 41,313 Due in 2022 18,191 Thereafter 2,052 Total $ 1,766,864
Maturities Of Time Open And Certificates Of Deposit Detailed Breakdown By Size Category	The following table shows a detailed breakdown of the maturities of time open and certificates of deposit, by size category, at December 31, 2017 . (In thousands) Certificates of Deposit under $100,000 Other Time Deposits under $100,000 Certificates of Deposit over $100,000 Other Time Deposits over $100,000 Total Due in 3 months or less $ 115,126 $ 24,019 $ 484,168 $ 3,744 $ 627,057 Due in over 3 through 6 months 115,595 26,607 197,173 5,438 344,813 Due in over 6 through 12 months 180,447 36,573 216,459 9,205 442,684 Due in over 12 months 82,789 53,490 205,085 10,946 352,310 Total $ 493,957 $ 140,689 $ 1,102,885 $ 29,333 $ 1,766,864

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Short-Term Borrowings	The following table sets forth selected information for short-term borrowings (borrowings with an original maturity of less than one year). (Dollars in thousands) Year End Weighted Rate Average Weighted Rate Average Balance Outstanding Maximum Outstanding at any Month End Balance at December 31 Federal funds purchased and repurchase agreements: 2017 .8 % .7 % $ 1,462,387 $ 1,984,071 $ 1,507,138 2016 .4 .3 1,266,093 1,723,905 1,723,905 2015 .2 .1 1,654,860 2,193,197 1,963,552

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule Of Components Of Income Tax Expense (Benefit)	The components of income tax expense from operations for the years ended December 31, 2017 , 2016 and 2015 were as follows: (In thousands) Current Deferred Total Year ended December 31, 2017: U.S. federal $ 89,154 $ 12,190 $ 101,344 State and local 7,735 1,427 9,162 Total $ 96,889 $ 13,617 $ 110,506 Year ended December 31, 2016: U.S. federal $ 116,753 $ (2,036 ) $ 114,717 State and local 9,457 (23 ) 9,434 Total $ 126,210 $ (2,059 ) $ 124,151 Year ended December 31, 2015: U.S. federal $ 102,607 $ 7,084 $ 109,691 State and local 6,551 348 6,899 Total $ 109,158 $ 7,432 $ 116,590
Schedule Of Income Tax Expense Recorded Directly To Stockholders Equity	The components of income tax (benefit) expense recorded directly to stockholders’ equity for the years ended December 31, 2017 , 2016 and 2015 were as follows: (In thousands) 2017 2016 2015 Unrealized gain (loss) on securities available for sale $ 2,104 $ (13,952 ) $ (19,634 ) Accumulated pension (benefit) loss (184 ) 778 1,478 Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes — (3,390 ) (2,132 ) Income tax (benefit) expense allocated to stockholders’ equity $ 1,920 $ (16,564 ) $ (20,288 )
Components Of Deferred Tax Assets And Liabilities	Significant components of the Company’s deferred tax assets and liabilities at December 31, 2017 and 2016 were as follows: (In thousands) 2017 2016 Deferred tax assets: Loans, principally due to allowance for loan losses $ 40,341 $ 61,233 Equity-based compensation 8,201 12,633 Deferred compensation 5,647 7,998 Private equity investments 5,473 9,667 Accrued expenses 5,245 16,638 Unearned fee income 3,701 3,819 Other 4,430 6,071 Total deferred tax assets 73,038 118,059 Deferred tax liabilities: Equipment lease financing 45,825 71,355 Unrealized gain on securities available for sale 13,603 18,572 Land, buildings and equipment 8,592 10,375 Undistributed earnings of subsidiaries 7,094 23 Intangibles 5,732 9,105 Other 6,569 8,765 Total deferred tax liabilities 87,415 118,195 Net deferred tax liabilities $ (14,377 ) $ (136 )
Schedule Of Company's Actual Income Tax Expense	A reconciliation between the expected federal income tax expense using the federal statutory tax rate of 35% and the Company’s actual income tax expense for 2017 , 2016 and 2015 is provided in the table below. The effective tax rate is calculated by dividing income taxes by income before income taxes less the non-controlling interest expense. (In thousands) 2017 2016 2015 Computed “expected” tax expense $ 150,461 $ 139,840 $ 133,112 Increase (decrease) in income taxes resulting from: Tax-exempt interest, net of cost to carry (20,295 ) (20,033 ) (19,083 ) Contribution of appreciated securities (10,864 ) — — Tax reform enactment (6,753 ) — — Share-based award payments (6,613 ) — — State and local income taxes, net of federal tax benefit 5,955 6,132 4,484 Tax deductible dividends on allocated shares held by the Company’s ESOP (966 ) (1,044 ) (1,093 ) Other (419 ) (744 ) (830 ) Total income tax expense $ 110,506 $ 124,151 $ 116,590
Schedule Of Accrued Liability For Unrecognized Tax Benefit	The activity in the accrued liability for unrecognized tax benefits for the years ended December 31, 2017 and 2016 was as follows: (In thousands) 2017 2016 Unrecognized tax benefits at beginning of year $ 1,228 $ 1,278 Gross increases – tax positions in prior period 5 — Gross decreases – tax positions in prior period — (1 ) Gross increases – current-period tax positions 268 269 Lapse of statute of limitations (293 ) (318 ) Unrecognized tax benefits at end of year $ 1,208 $ 1,228 The Company and its subsidiaries are subject to income tax by federal, state and local government taxing authorities. Tax years 2014 through 2017 remain open to examination for U.S. federal income tax as well as income tax in major state taxing jurisdictions.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Employee Benefits Charged To Operating Expenses	Employee benefits charged to operating expenses are summarized in the table below. Substantially all of the Company’s employees are covered by a defined contribution (401(k)) plan, under which the Company makes matching contributions. (In thousands) 2017 2016 2015 Payroll taxes $ 24,402 $ 23,210 $ 22,235 Medical plans 25,143 25,497 20,659 401(k) plan 14,244 13,562 12,841 Pension plans 704 987 1,495 Other 2,883 3,214 2,950 Total employee benefits $ 67,376 $ 66,470 $ 60,180
Components Of The Net Pension Cost	The following items are components of the net pension cost for the years ended December 31, 2017 , 2016 and 2015 . (In thousands) 2017 2016 2015 Service cost-benefits earned during the year $ 621 $ 500 $ 503 Interest cost on projected benefit obligation 3,826 3,944 4,762 Expected return on plan assets (5,785 ) (5,751 ) (6,092 ) Amortization of prior service cost (271 ) (271 ) (271 ) Amortization of unrecognized net loss 2,313 2,565 2,593 Net periodic pension cost $ 704 $ 987 $ 1,495
Summary Of Pension Plans Funded Status	The following table sets forth the pension plans’ funded status, using valuation dates of December 31, 2017 and 2016 . (In thousands ) 2017 2016 Change in projected benefit obligation Projected benefit obligation at prior valuation date $ 116,695 $ 117,562 Service cost 621 500 Interest cost 3,826 3,944 Benefits paid (6,780 ) (6,322 ) Actuarial (gain) loss 6,305 1,011 Projected benefit obligation at valuation date 120,667 116,695 Change in plan assets Fair value of plan assets at prior valuation date 99,537 99,325 Actual return on plan assets 9,564 6,513 Employer contributions 5,939 21 Benefits paid (6,780 ) (6,322 ) Fair value of plan assets at valuation date 108,260 99,537 Funded status and net amount recognized at valuation date $ (12,407 ) $ (17,158 )
Schedule Of Amounts Not Yet Reflected In Net Periodic Benefit Cost And Included In Accumulated Other Comprehensive Income (Loss), Pre-Tax Basis	Amounts not yet reflected in net periodic benefit cost and included in accumulated other comprehensive income (loss) at December 31, 2017 and 2016 are shown below, including amounts recognized in other comprehensive income during the periods. All amounts are shown on a pre-tax basis. (In thousands) 2017 2016 Prior service cost $ 1,806 $ 2,077 Accumulated loss (33,499 ) (33,285 ) Accumulated other comprehensive loss (31,693 ) (31,208 ) Cumulative employer contributions in excess of net periodic benefit cost 19,286 14,050 Net amount recognized as an accrued benefit liability on the December 31 balance sheet $ (12,407 ) $ (17,158 ) Net loss arising during period (2,527 ) (248 ) Amortization of net loss 2,313 2,565 Amortization of prior service cost (271 ) (271 ) Total recognized in other comprehensive income $ (485 ) $ 2,046 Total income (expense) recognized in net periodic pension cost and other comprehensive income $ (1,189 ) $ 1,059
Assumptions On A Weighted Average Basis, Used In Accounting For Plans	The following assumptions, on a weighted average basis, were used in accounting for the plans. 2017 2016 2015 Determination of benefit obligation at year end: Effective discount rate for benefit obligations 3.57 % 4.05 % 4.15 % Assumed credit on cash balance accounts 5.00 % 5.00 % 5.00 % Determination of net periodic benefit cost for year ended: Effective discount rate for benefit obligations 3.95 % 4.16 % 3.95 % Effective rate for interest on benefit obligations 3.28 % 3.38 % NA Long-term rate of return on assets 6.00 % 6.00 % 6.00 % Assumed credit on cash balance accounts 5.00 % 5.00 % 5.00 %
Fair Value Of Pension Plan Asset Category	The following table shows the fair values of the Company’s pension plan assets by asset category at December 31, 2017 and 2016 . Information about the valuation techniques and inputs used to measure fair value are provided in Note 15 on Fair Value Measurements. Fair Value Measurements (In thousands) Total Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017 Assets: U.S. government obligations $ 3,719 $ 3,719 $ — $ — Government-sponsored enterprise obligations (a) 1,282 — 1,282 — State and municipal obligations 8,527 — 8,527 — Agency mortgage-backed securities (b) 7,896 — 7,896 — Non-agency mortgage-backed securities 4,891 — 4,891 — Asset-backed securities 3,833 — 3,833 — Corporate bonds (c) 37,457 — 37,457 — Equity securities and mutual funds: (d) Mutual funds 6,979 6,979 — — Common stocks 23,744 23,744 — — International developed markets funds 7,870 7,870 — — Emerging markets funds 2,062 2,062 — — Total $ 108,260 $ 44,374 $ 63,886 $ — December 31, 2016 Assets: U.S. government obligations $ 3,621 $ 3,621 $ — $ — Government-sponsored enterprise obligations (a) 1,215 — 1,215 — State and municipal obligations 9,148 — 9,148 — Agency mortgage-backed securities (b) 4,073 — 4,073 — Non-agency mortgage-backed securities 5,437 — 5,437 — Asset-backed securities 5,275 — 5,275 — Corporate bonds (c) 34,037 — 34,037 — Equity securities and mutual funds: (d) Mutual funds 10,393 10,393 — — Common stocks 20,141 20,141 — — International developed markets funds 5,100 5,100 — — Emerging markets funds 1,097 1,097 — — Total $ 99,537 $ 40,352 $ 59,185 $ — (a) This category represents bonds (excluding mortgage-backed securities) issued by agencies such as the Federal Home Loan Bank, the Federal Home Loan Mortgage Corp and the Federal National Mortgage Association. (b) This category represents mortgage-backed securities issued by the agencies mentioned in (a). (c) This category represents investment grade bonds issued in the U.S., primarily by domestic issuers, representing diverse industries. (d) This category represents investments in individual common stocks and equity funds. These holdings are diversified, largely across the financial services, consumer goods, healthcare, electronic technology and technology servic
Future Benefit Payments	The following future benefit payments are expected to be paid: (In thousands) 2018 $ 7,133 2019 7,231 2020 7,413 2021 7,534 2022 7,473 2023 - 2027 37,421

Stock-Based Compensation and 39

Stock-Based Compensation and Directors Stock Purchase Plan (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Summary Of The Status Of Nonvested Share Awards	A summary of the status of the Company’s nonvested share awards as of December 31, 2017 and changes during the year then ended is presented below. Shares Weighted Average Grant Date Fair Value Nonvested at January 1, 2017 1,461,713 $ 33.02 Granted 263,123 54.56 Vested (442,435 ) 29.41 Forfeited (27,883 ) 39.12 Canceled — — Nonvested at December 31, 2017 1,254,518 $ 38.67
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Table Text Block]	2017 2016 2015 Weighted per share average fair value at grant date $11.94 $6.79 $6.55 Assumptions: Dividend yield 1.6 % 2.2 % 2.2 % Volatility 21.1 % 21.2 % 21.3 % Risk-free interest rate 2.4 % 1.8 % 1.8 % Expected term 7.0 years 7.2 years 7.2 years
Summary Of SAR Activity	( Dollars in thousands, except per share data) Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at January 1, 2017 1,390,782 $ 32.89 Granted 173,740 54.79 Forfeited (13,325 ) 42.19 Expired (878 ) 34.75 Exercised (371,033 ) 29.30 Outstanding at December 31, 2017 1,179,286 $ 37.13 6.2 years $ 22,073 Exercisable at December 31, 2017 630,135 $ 32.60 4.6 years $ 14,645
Schedule Of Additional Information About Stock Options and SARs Exercises	Additional information about stock options and SARs exercised is presented below. (In thousands) 2017 2016 2015 Intrinsic value of options and SARs exercised $ 9,310 $ 8,854 $ 7,541 Cash received from options and SARs exercised $ — $ — $ 1,914 Tax benefit realized from options and SARs exercised $ 2,698 $ 1,781 $ 1,041

Accumulated Other Comprehensi40

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components Of Accumulated Other Comprehensive Income (Loss)	Unrealized Gains (Losses) on Securities (1) Pension Loss (2) Total Accumulated Other Comprehensive Income (In thousands) OTTI Other Balance January 1, 2017 $ 2,975 $ 27,328 $ (19,328 ) $ 10,975 Other comprehensive income (loss) before reclassifications 279 36,307 (2,527 ) 34,059 Amounts reclassified from accumulated other comprehensive income 385 (31,433 ) 2,042 (29,006 ) Current period other comprehensive income (loss), before tax 664 4,874 (485 ) 5,053 Income tax (expense) benefit (252 ) (1,852 ) 184 (1,920 ) Current period other comprehensive income (loss), net of tax 412 3,022 (301 ) 3,133 Transfer of unrealized gain on securities for which impairment was not previously recognized 24 (24 ) — — Balance December 31, 2017 $ 3,411 $ 30,326 $ (19,629 ) $ 14,108 Balance January 1, 2016 $ 3,316 $ 49,750 $ (20,596 ) $ 32,470 Other comprehensive loss before reclassifications (820 ) (36,057 ) (248 ) (37,125 ) Amounts reclassified from accumulated other comprehensive income 270 (108 ) 2,294 2,456 Current period other comprehensive income (loss), before tax (550 ) (36,165 ) 2,046 (34,669 ) Income tax (expense) benefit 209 13,743 (778 ) 13,174 Current period other comprehensive income (loss), net of tax (341 ) (22,422 ) 1,268 (21,495 ) Balance December 31, 2016 $ 2,975 $ 27,328 $ (19,328 ) $ 10,975 (1) The pre-tax amounts reclassified from accumulated other comprehensive income are included in "investment securities gains (losses), net" in the consolidated statements of income. (2) The pre-tax amounts reclassified from accumulated other comprehensive income are included in the computation of net periodic pension cost as "amortization of prior service cost" and "amortization of unrecognized net loss" (see Note 9), for inclusion in the consolidated statements of income.

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule Of Financial Information By Segment	Segment Income Statement Data (In thousands) Consumer Commercial Wealth Segment Totals Other/Elimination Consolidated Totals Year ended December 31, 2017: Net interest income $ 279,031 $ 328,345 $ 47,264 $ 654,640 $ 79,039 $ 733,679 Provision for loan losses (41,829 ) 205 (41 ) (41,665 ) (3,579 ) (45,244 ) Non-interest income 136,554 194,581 158,175 489,310 (2,706 ) 486,604 Investment securities gains, net — — — — 25,051 25,051 Non-interest expense (290,905 ) (290,874 ) (120,458 ) (702,237 ) (67,447 ) (769,684 ) Income before income taxes $ 82,851 $ 232,257 $ 84,940 $ 400,048 $ 30,358 $ 430,406 Year ended December 31, 2016: Net interest income $ 268,654 $ 311,704 $ 44,113 $ 624,471 $ 55,578 $ 680,049 Provision for loan losses (36,042 ) 4,378 (122 ) (31,786 ) (4,532 ) (36,318 ) Non-interest income 131,988 199,384 144,661 476,033 (1,641 ) 474,392 Investment securities losses, net — — — — (53 ) (53 ) Non-interest expense (282,061 ) (284,432 ) (113,888 ) (680,381 ) (36,684 ) (717,065 ) Income before income taxes $ 82,539 $ 231,034 $ 74,764 $ 388,337 $ 12,668 $ 401,005 Year ended December 31, 2015: Net interest income $ 266,328 $ 296,510 $ 42,653 $ 605,491 $ 28,829 $ 634,320 Provision for loan losses (34,864 ) 1,032 75 (33,757 ) 5,030 (28,727 ) Non-interest income 119,561 194,133 136,374 450,068 (1,929 ) 448,139 Investment securities gains, net — — — — 6,320 6,320 Non-interest expense (273,378 ) (267,343 ) (108,755 ) (649,476 ) (27,011 ) (676,487 ) Income before income taxes $ 77,647 $ 224,332 $ 70,347 $ 372,326 $ 11,239 $ 383,565
Segment Balance Sheet Data	Segment Balance Sheet Data (In thousands) Consumer Commercial Wealth Segment Totals Other/Elimination Consolidated Totals Average balances for 2017: Assets $ 2,610,045 $ 8,830,584 $ 1,218,598 $ 12,659,227 $ 12,372,381 $ 25,031,608 Loans, including held for sale 2,471,578 8,635,035 1,209,792 12,316,405 1,312,746 13,629,151 Goodwill and other intangible assets 76,734 68,538 746 146,018 — 146,018 Deposits 10,190,613 8,301,004 2,090,582 20,582,199 12,587 20,594,786 Average balances for 2016: Assets $ 2,673,915 $ 8,267,963 $ 1,116,969 $ 12,058,847 $ 12,497,624 $ 24,556,471 Loans, including held for sale 2,533,528 8,072,528 1,108,211 11,714,267 1,239,221 12,953,488 Goodwill and other intangible assets 75,971 68,848 746 145,565 — 145,565 Deposits 9,956,327 8,243,394 2,084,940 20,284,661 46,252 20,330,913

Common and Preferred Stock (Tab

Common and Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2017
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Summary Of Components Used To Calculate Basic And Diluted Income Per Share	(In thousands, except per share data) 2017 2016 2015 Basic income per common share: Net income attributable to Commerce Bancshares, Inc. $ 319,383 $ 275,391 $ 263,730 Less preferred stock dividends 9,000 9,000 9,000 Net income available to common shareholders 310,383 266,391 254,730 Less income allocated to nonvested restricted stock 3,848 3,698 3,548 Net income allocated to common stock $ 306,535 $ 262,693 $ 251,182 Weighted average common shares outstanding 105,555 105,243 108,016 Basic income per common share $ 2.90 $ 2.50 $ 2.33 Diluted income per common share: Net income available to common shareholders $ 310,383 $ 266,391 $ 254,730 Less income allocated to nonvested restricted stock 3,838 3,692 3,541 Net income allocated to common stock $ 306,545 $ 262,699 $ 251,189 Weighted average common shares outstanding 105,555 105,243 108,016 Net effect of the assumed exercise of stock-based awards -- based on the treasury stock method using the average market price for the respective periods 372 281 336 Weighted average diluted common shares outstanding 105,927 105,524 108,352 Diluted income per common share $ 2.89 $ 2.49 $ 2.32
Schedule Of Activity In The Outstanding Shares Of The Company's Common Stock	The table below shows activity in the outstanding shares of the Company’s common stock during the past three years. Shares in the table below are presented on an historical basis and have not been restated for the annual 5% stock dividends. Years Ended December 31 (In thousands) 2017 2016 2015 Shares outstanding at January 1 101,461 97,226 96,327 Issuance of stock: Awards and sales under employee and director plans 403 397 435 5% stock dividend 5,078 4,831 4,641 Purchases of treasury stock under accelerated share repurchase programs — — (3,635 ) Other purchases of treasury stock (315 ) (959 ) (535 ) Other (12 ) (34 ) (7 ) Shares outstanding at December 31 106,615 101,461 97,226

Regulatory Capital Requiremen43

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
Schedule Of Capital Amounts And Ratios On Consolidated Basis	The following tables show the capital amounts and ratios for the Company (on a consolidated basis) and the Bank, together with the minimum capital adequacy and well-capitalized capital requirements, at the last two year ends. Actual Minimum Capital Adequacy Requirement Well-Capitalized Capital Requirement (Dollars in thousands) Amount Ratio Amount Ratio Amount Ratio December 31, 2017 Total Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,747,863 14.35 % $ 1,531,996 8.00 % N.A. N.A. Commerce Bank 2,428,789 12.76 1,522,361 8.00 $ 1,902,951 10.00 % Tier I Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,567,264 13.41 % $ 1,148,997 6.00 % N.A. N.A. Commerce Bank 2,268,131 11.92 1,141,771 6.00 $ 1,522,361 8.00 % Tier I Common Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,422,480 12.65 % $ 861,748 4.50 % N.A. N.A. Commerce Bank 2,268,131 11.92 856,328 4.50 $ 1,236,918 6.50 % Tier I Capital (to adjusted quarterly average assets): (Leverage Ratio) Commerce Bancshares, Inc. (consolidated) $ 2,567,264 10.39 % $ 988,653 4.00 % N.A. N.A. Commerce Bank 2,268,131 9.20 986,240 4.00 $ 1,232,800 5.00 % December 31, 2016 Total Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,529,675 13.32 % $ 1,519,578 8.00 % N.A. N.A. Commerce Bank 2,268,845 12.00 1,512,471 8.00 $ 1,890,589 10.00 % Tier I Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,352,154 12.38 % $ 1,139,684 6.00 % N.A. N.A. Commerce Bank 2,111,797 11.17 1,134,353 6.00 $ 1,512,471 8.00 % Tier I Common Capital (to risk-weighted assets): Commerce Bancshares, Inc. (consolidated) $ 2,207,370 11.62 % $ 854,763 4.50 % N.A. N.A. Commerce Bank 2,111,797 11.17 850,765 4.50 $ 1,228,883 6.50 % Tier I Capital (to adjusted quarterly average assets): (Leverage Ratio) Commerce Bancshares, Inc. (consolidated) $ 2,352,154 9.55 % $ 985,698 4.00 % N.A. N.A. Commerce Bank 2,111,797 8.59 983,081 4.00 $ 1,228,851 5.00 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis	The table below presents the carrying values of assets and liabilities measured at fair value on a recurring basis at December 31, 2017 and 2016 . There were no transfers among levels during these years. Fair Value Measurements Using (In thousands) Total Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017 Assets: Residential mortgage loans held for sale $ 15,327 $ — $ 15,327 $ — Available for sale securities: U.S. government and federal agency obligations 917,147 917,147 — — Government-sponsored enterprise obligations 406,363 — 406,363 — State and municipal obligations 1,611,366 — 1,594,350 17,016 Agency mortgage-backed securities 3,040,913 — 3,040,913 — Non-agency mortgage-backed securities 905,793 — 905,793 — Asset-backed securities 1,492,800 — 1,492,800 — Other debt securities 351,060 — 351,060 — Equity securities 48,838 19,864 28,974 — Trading securities 18,269 — 18,269 — Private equity investments 55,752 — — 55,752 Derivatives * 8,349 — 7,723 626 Assets held in trust for deferred compensation plan 12,843 12,843 — — Total assets 8,884,820 949,854 7,861,572 73,394 Liabilities: Derivatives * 8,074 — 7,951 123 Liabilities held in trust for deferred compensation plan 12,843 12,843 — — Total liabilities $ 20,917 $ 12,843 $ 7,951 $ 123 December 31, 2016 Assets: Residential mortgage loans held for sale $ 9,263 $ — $ 9,263 $ — Available for sale securities: U.S. government and federal agency obligations 920,904 920,904 — — Government-sponsored enterprise obligations 449,998 — 449,998 — State and municipal obligations 1,778,214 — 1,761,532 16,682 Agency mortgage-backed securities 2,685,931 — 2,685,931 — Non-agency mortgage-backed securities 1,055,639 — 1,055,639 — Asset-backed securities 2,381,301 — 2,381,301 — Other debt securities 325,953 — 325,953 — Equity securities 51,263 24,967 26,296 — Trading securities 22,225 — 22,225 — Private equity investments 50,820 — — 50,820 Derivatives * 13,566 — 13,146 420 Assets held in trust for deferred compensation plan 10,261 10,261 — — Total assets 9,755,338 956,132 8,731,284 67,922 Liabilities: Derivatives * 13,339 — 13,177 162 Liabilities held in trust for deferred compensation plan 10,261 10,261 — — Total liabilities $ 23,600 $ 10,261 $ 13,177 $ 162 * The fair value of each class of derivative is shown in Note 17. .
Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis	The changes in Level 3 assets and liabilities measured at fair value on a recurring basis are summarized as follows: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (In thousands) State and Municipal Obligations Private Equity Investments Derivatives Total Year ended December 31, 2017: Balance at January 1, 2017 $ 16,682 $ 50,820 $ 258 $ 67,760 Total gains or losses (realized/unrealized): Included in earnings — (5,833 ) 266 (5,567 ) Included in other comprehensive income 882 — — 882 Investment securities called (600 ) — — (600 ) Discount accretion 52 — — 52 Purchases of private equity securities — 13,352 — 13,352 Sale / pay down of private equity securities — (2,621 ) — (2,621 ) Capitalized interest/dividends — 34 — 34 Purchase of risk participation agreement — — 70 70 Sale of risk participation agreement — — (91 ) (91 ) Balance at December 31, 2017 $ 17,016 $ 55,752 $ 503 $ 73,271 Total gains or losses for the year included in earnings attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2017 $ — $ (5,658 ) $ 615 $ (5,043 ) Year ended December 31, 2016: Balance at January 1, 2016 $ 17,195 $ 63,032 $ 69 $ 80,296 Total gains or losses (realized/unrealized): Included in earnings — (3,739 ) 43 (3,696 ) Included in other comprehensive income 583 — — 583 Investment securities called (1,200 ) — — (1,200 ) Discount accretion 104 — — 104 Purchases of private equity securities — 9,906 — 9,906 Sale / pay down of private equity securities — (18,471 ) — (18,471 ) Capitalized interest/dividends — 92 — 92 Purchase of risk participation agreement — — 404 404 Sale of risk participation agreement — — (258 ) (258 ) Balance at December 31, 2016 $ 16,682 $ 50,820 $ 258 $ 67,760 Total gains or losses for the year included in earnings attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2016 $ — $ (5,914 ) $ 306 $ (5,608 )
Summary Of Gains And Losses On Level 3 Assets And Liabilities	Gains and losses on the Level 3 assets and liabilities in the table above are reported in the following income categories: (In thousands) Loan Fees and Sales Other Non-Interest Income Investment Securities Gains (Losses), Net Total Year ended December 31, 2017: Total gains or losses included in earnings $ 231 $ 35 $ (5,833 ) $ (5,567 ) Change in unrealized gains or losses relating to assets still held at December 31, 2017 $ 580 $ 35 $ (5,658 ) $ (5,043 ) Year ended December 31, 2016: Total gains or losses included in earnings $ 87 $ (44 ) $ (3,739 ) $ (3,696 ) Change in unrealized gains or losses relating to assets still held at December 31, 2016 $ 350 $ (44 ) $ (5,914 ) $ (5,608 )
Summary Of Quantitative Information About Level 3 Fair Value Measurements	Level 3 Inputs As shown above, the Company's significant Level 3 measurements which employ unobservable inputs that are readily quantifiable pertain to auction rate securities (ARS) held by the Bank, investments in portfolio concerns held by the Company's private equity subsidiaries, and held for sale residential mortgage loan commitments. ARS are included in state and municipal securities and totaled $17.0 million at December 31, 2017 , while private equity investments, included in non-marketable securities, totaled $55.8 million . Information about these inputs is presented in the table and discussions below. Quantitative Information about Level 3 Fair Value Measurements Weighted Valuation Technique Unobservable Input Range Average Auction rate securities Discounted cash flow Estimated market recovery period 5 years Estimated market rate 3.1% - 4.5% Private equity investments Market comparable companies EBITDA multiple 4.0 - 6.0 Mortgage loan commitments Discounted cash flow Probability of funding 50.4% - 100.0% 76.0% Embedded servicing value (.3)% - 2.0% 1.1%
Schedule Of Fair Value Disclosures Measured On Nonrecurring Basis [Table Text Block]	Instruments Measured at Fair Value on a Nonrecurring Basis For assets measured at fair value on a nonrecurring basis during 2017 and 2016 , and still held as of December 31, 2017 and 2016 , the following table provides the adjustments to fair value recognized during the respective periods, the level of valuation assumptions used to determine each adjustment, and the carrying value of the related individual assets or portfolios at December 31, 2017 and 2016 . Fair Value Measurements Using (In thousands) Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Gains (Losses) Balance at December 31, 2017 Collateral dependent impaired loans $ 1,236 $ — $ — $ 1,236 $ (617 ) Mortgage servicing rights 4,653 — — 4,653 13 Foreclosed assets — — — — (9 ) Long-lived assets 3,378 — — 3,378 (724 ) Balance at December 31, 2016 Collateral dependent impaired loans $ 1,331 $ — $ — $ 1,331 $ (1,700 ) Mortgage servicing rights 2,868 — — 2,868 7 Foreclosed assets 18 — — 18 (20 ) Long-lived assets 2,408 — — 2,408 (1,054 )

Fair Value Of Financial Instr45

Fair Value Of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule Of Estimated Fair Value Of Financial Instruments	The estimated fair values of the Company’s financial instruments are as follows: Fair Value Hierarchy Level 2017 2016 (In thousands) Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Financial Assets Loans: Business Level 3 $ 4,958,554 $ 4,971,401 $ 4,776,365 $ 4,787,469 Real estate - construction and land Level 3 968,820 979,389 791,236 800,426 Real estate - business Level 3 2,697,452 2,702,598 2,643,374 2,658,093 Real estate - personal Level 3 2,062,787 2,060,443 2,010,397 2,005,227 Consumer Level 3 2,104,487 2,074,129 1,990,801 1,974,784 Revolving home equity Level 3 400,587 400,333 413,634 414,499 Consumer credit card Level 3 783,864 798,093 776,465 794,856 Overdrafts Level 3 7,123 7,123 10,464 10,464 Loans held for sale Level 2 21,398 21,398 14,456 14,456 Investment securities: Available for sale Level 1 937,011 937,011 945,871 945,871 Available for sale Level 2 7,820,253 7,820,253 8,686,650 8,686,650 Available for sale Level 3 17,016 17,016 16,682 16,682 Trading Level 2 18,269 18,269 22,225 22,225 Non-marketable Level 3 100,758 100,758 99,558 99,558 Federal funds sold Level 1 42,775 42,775 15,470 15,470 Securities purchased under agreements to resell Level 3 700,000 695,194 725,000 728,179 Interest earning deposits with banks Level 1 30,631 30,631 272,275 272,275 Cash and due from banks Level 1 438,439 438,439 494,690 494,690 Derivative instruments Level 2 7,723 7,723 13,146 13,146 Derivative instruments Level 3 626 626 420 420 Assets held in trust for deferred compensation plan Level 1 12,843 12,843 10,261 10,261 Financial Liabilities Non-interest bearing deposits Level 1 $ 7,158,962 $ 7,158,962 $ 7,429,398 $ 7,429,398 Savings, interest checking and money market deposits Level 1 11,499,620 11,499,620 11,430,789 11,430,789 Time open and certificates of deposit Level 3 1,766,864 1,768,780 2,240,908 2,235,218 Federal funds purchased Level 1 202,370 202,370 52,840 52,840 Securities sold under agreements to repurchase Level 3 1,304,768 1,305,375 1,671,065 1,671,227 Other borrowings Level 3 1,758 1,758 102,049 104,298 Derivative instruments Level 2 7,951 7,951 13,177 13,177 Derivative instruments Level 3 123 123 162 162 Liabilities held in trust for deferred compensation plan Level 1 12,843 12,843 10,261 10,261

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instrument Detail [Abstract]
Schedule Of Notional Amounts Of Derivative Instruments	The notional amounts of the Company’s derivative instruments are shown in the table below. These contractual amounts, along with other terms of the derivative, are used to determine amounts to be exchanged between counterparties and are not a measure of loss exposure. The Company's derivative instruments are accounted for as free-standing derivatives, and changes in their fair value are recorded in current earnings. December 31 (In thousands) 2017 2016 Interest rate swaps $ 1,741,412 $ 1,685,099 Interest rate caps 31,776 59,379 Credit risk participation agreements 133,488 121,514 Foreign exchange contracts 11,826 4,046 Mortgage loan commitments 17,110 12,429 Mortgage loan forward sale contracts 2,566 6,626 Forward TBA contracts 25,000 15,000 Total notional amount $ 1,963,178 $ 1,904,093
Schedule Of Fair Values Of Derivative Instruments	The fair values of the Company’s derivative instruments are shown in the table below. Information about the valuation methods used to measure fair value is provided in Note 15 on Fair Value Measurements. Derivative instruments with a positive fair value (asset derivatives) are reported in other assets in the consolidated balance sheets while derivative instruments with a negative fair value (liability derivatives) are reported in other liabilities in the consolidated balance sheets. As mentioned in Note 15, effective January 2017, certain collateral posted to and from the Company's clearing counterparty has been offset against the fair values of cleared swaps, such that at December 31, 2017 , the positive fair values of cleared swaps were reduced by $4.5 million and the negative fair values of cleared swaps were reduced by $4.3 million , as reflected in the table below. Asset Derivatives Liability Derivatives December 31 December 31 2017 2016 2017 2016 (In thousands ) Fair Value Fair Value Derivative instruments: Interest rate swaps $ 7,674 $ 12,987 $ (7,857 ) $ (12,987 ) Interest rate caps 16 78 (16 ) (78 ) Credit risk participation agreements 46 65 (123 ) (156 ) Foreign exchange contracts 21 66 (40 ) (4 ) Mortgage loan commitments 580 355 — (6 ) Mortgage loan forward sale contracts 8 — (7 ) (63 ) Forward TBA contracts 4 15 (31 ) (45 ) Total $ 8,349 $ 13,566 $ (8,074 ) $ (13,339 )
Summary Of The Effects Of Derivative Instruments On Consolidated Statements Of Income	The effects of derivative instruments on the consolidated statements of income are shown in the table below. Location of Gain or (Loss) Recognized in Income on Derivative Amount of Gain or (Loss) Recognized in Income on Derivative For the Years Ended December 31 (In thousands) 2017 2016 2015 Derivative instruments: Interest rate swaps Other non-interest income $ 1,978 $ 5,927 $ 4,309 Interest rate caps Other non-interest income — — 32 Credit risk participation agreements Other non-interest income 35 (44 ) 57 Foreign exchange contracts: Other non-interest income (80 ) 55 253 Mortgage loan commitments Loan fees and sales 231 87 263 Mortgage loan forward sale contracts Loan fees and sales 64 (63 ) — Forward TBA contracts Loan fees and sales (648 ) 79 82 Total $ 1,580 $ 6,041 $ 4,996 The following table shows the extent to which assets and liabilities relating to derivative instruments have been offset in the consolidated balance sheets. It also provides information about these instruments which are subject to an enforceable master netting arrangement, irrespective of whether they are offset, and the extent to which the instruments could potentially be offset. Also shown is collateral received or pledged in the form of other financial instruments, which is generally cash or marketable securities. The collateral amounts in this table are limited to the outstanding balance of the related asset or liability (after netting is applied); thus amounts of excess collateral are not shown. Most of the derivatives in the following table were transacted under master netting arrangements that contain a conditional right of offset, such as close-out netting, upon default. The Company is party to master netting arrangements with most of its swap derivative counterparties; however, the Company does not offset derivative assets and liabilities under these arrangements on its consolidated balance sheet. Collateral, usually in the form of marketable securities, is exchanged between the Company and dealer bank counterparties and is generally subject to thresholds and transfer minimums. By contract, it may be sold or re-pledged by the secured party until recalled at a subsequent valuation date by the pledging party. For those swap transactions requiring central clearing, the Company posts cash and securities to its clearing agency. Collateral positions are valued daily, and adjustments to amounts received and pledged by the Company are made as appropriate to maintain proper collateralization for these transactions. Swap derivative transactions with customers are generally secured by rights to non-financial collateral, such as real and personal property, which is not shown in the table below.
Balance Sheet Offsetting, Derivatives [Table Text Block]	Gross Amounts Not Offset in the Balance Sheet (In thousands) Gross Amount Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments Available for Offset Collateral Received/Pledged Net Amount December 31, 2017 Assets: Derivatives subject to master netting agreements $ 7,726 $ — $ 7,726 $ (233 ) $ (824 ) $ 6,669 Derivatives not subject to master netting agreements 623 — 623 Total derivatives 8,349 — 8,349 Liabilities: Derivatives subject to master netting agreements 7,935 — 7,935 (233 ) (1,570 ) 6,132 Derivatives not subject to master netting agreements 139 — 139 Total derivatives 8,074 — 8,074 December 31, 2016 Assets: Derivatives subject to master netting agreements $ 13,111 $ — $ 13,111 $ (3,391 ) $ — $ 9,720 Derivatives not subject to master netting agreements 455 — 455 Total derivatives 13,566 — 13,566 Liabilities: Derivatives subject to master netting agreements 13,124 — 13,124 (3,391 ) (5,292 ) 4,441 Derivatives not subject to master netting agreements 215 — 215 Total derivatives 13,339 — 13,339

Resale and Repurchase Agreeme47

Resale and Repurchase Agreements Resale and Repurchase Agreements (Tables)	12 Months Ended
	Dec. 31, 2017
Offsetting [Abstract]
Offsetting, Resale and Repurchase Agreements [Table Text Block]	The following table shows the extent to which assets and liabilities relating to securities purchased under agreements to resell (resale agreements) and securities sold under agreements to repurchase (repurchase agreements) have been offset in the consolidated balance sheets, in addition to the extent to which they could potentially be offset. Also shown is collateral received or pledged, which consists of marketable securities. The collateral amounts in the table are limited to the outstanding balances of the related asset or liability (after netting is applied); thus amounts of excess collateral are not shown. The agreements in the following table were transacted under master netting arrangements that contain a conditional right of offset, such as close-out netting, upon default. Resale and repurchase agreements are agreements to purchase/sell securities subject to an obligation to resell/repurchase the same or similar securities. They are accounted for as collateralized financing transactions, not as sales and purchases of the securities portfolio. The securities collateral accepted or pledged in resale and repurchase agreements with other financial institutions also may be sold or re-pledged by the secured party, but is usually delivered to and held by third party trustees. The Company generally retains custody of securities pledged for repurchase agreements with customers. The Company is party to several agreements commonly known as collateral swaps. These agreements involve the exchange of collateral under simultaneous repurchase and resale agreements with the same financial institution counterparty. These repurchase and resale agreements have the same principal amounts, inception dates, and maturity dates and have been offset against each other in the balance sheet, having met the accounting requirements for this treatment. The collateral swaps totaled $650.0 million at December 31, 2017 and $550.0 million at December 31, 2016 . At December 31, 2017 , the Company had posted collateral of $661.4 million in marketable securities, consisting of agency mortgage-backed bonds and treasuries, and had accepted $661.3 million in investment grade asset-backed, commercial mortgage-backed, and corporate bonds. Gross Amounts Not Offset in the Balance Sheet (In thousands) Gross Amount Recognized Gross Amounts Offset in the Balance Sheet Net Amounts Presented in the Balance Sheet Financial Instruments Available for Offset Securities Collateral Received/Pledged Net Amount December 31, 2017 Total resale agreements, subject to master netting arrangements $ 1,350,000 $ (650,000 ) $ 700,000 $ — $ (700,000 ) $ — Total repurchase agreements, subject to master netting arrangements 1,954,768 (650,000 ) 1,304,768 — (1,304,768 ) — December 31, 2016 Total resale agreements, subject to master netting arrangements $ 1,275,000 $ (550,000 ) $ 725,000 $ — $ (725,000 ) $ — Total repurchase agreements, subject to master netting arrangements 2,221,065 (550,000 ) 1,671,065 — (1,671,065 ) —
Schedule of Underlying Assets of Repurchase Agreements [Table Text Block]	The table below shows the remaining contractual maturities of repurchase agreements outstanding at December 31, 2017 and 2016, in addition to the various types of marketable securities that have been pledged as collateral for these borrowings. Remaining Contractual Maturity of the Agreements (In thousands) Overnight and continuous Up to 90 days Greater than 90 days Total December 31, 2017 Repurchase agreements, secured by: U.S. government and federal agency obligations $ 271,820 $ 1,731 $ 450,000 $ 723,551 Government-sponsored enterprise obligations 149,111 — — 149,111 Agency mortgage-backed securities 737,975 9,750 200,000 947,725 Asset-backed securities 89,601 30,000 — 119,601 Other debt securities 14,780 — — 14,780 Total repurchase agreements, gross amount recognized $ 1,263,287 $ 41,481 $ 650,000 $ 1,954,768 December 31, 2016 Repurchase agreements, secured by: U.S. government and federal agency obligations $ 294,600 $ — $ 300,000 $ 594,600 Government-sponsored enterprise obligations 147,694 — 3,237 150,931 Agency mortgage-backed securities 693,851 24,380 252,473 970,704 Asset-backed securities 474,830 30,000 — 504,830 Total repurchase agreements, gross amount recognized $ 1,610,975 $ 54,380 $ 555,710 $ 2,221,065

Commitments, Contingencies An48

Commitments, Contingencies And Guarantees (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Summary Of Minimum Lease Commitments	A summary of minimum lease commitments follows: (In thousands) Type of Property Year Ended December 31 Real Property Equipment Total 2018 $ 5,981 $ 215 $ 6,196 2019 4,876 75 4,951 2020 3,861 32 3,893 2021 3,162 14 3,176 2022 2,678 — 2,678 After 13,383 — 13,383 Total minimum lease payments $ 34,277
Schedule Of Off-Balance Sheet Instruments Commitments	The following table summarizes these commitments at December 31: (In thousands) 2017 2016 Commitments to extend credit: Credit card $ 5,102,556 $ 4,932,955 Other 5,737,181 5,508,686 Standby letters of credit, net of participations 387,811 391,899 Commercial letters of credit 4,498 2,962

Related Parties (Tables)

Related Parties (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Schedule Of Related Party Expenses	The Company’s Chief Executive Officer, its Vice Chairman, and its President are directors of Tower Properties Company (Tower) and, together with members of their immediate families, beneficially own approximately 66% of the outstanding stock of Tower. At December 31, 2017 , Tower owned 270,646 shares of Company stock. Tower is primarily engaged in the business of owning, developing, leasing and managing real property. Payments from the Company and its affiliates to Tower are summarized below. These payments, with the exception of dividend payments, relate to property management services, including construction oversight, on three Company-owned office buildings and related parking garages in downtown Kansas City. (In thousands) 2017 2016 2015 Leasing agent fees $ 32 $ 101 $ 66 Operation of parking garages 82 184 75 Building management fees 1,954 1,832 1,850 Property construction management fees 146 147 322 Dividends paid on Company stock held by Tower 232 221 210 Total $ 2,446 $ 2,485 $ 2,523

Parent Company Condensed Fina50

Parent Company Condensed Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheets	Condensed Balance Sheets December 31 (In thousands) 2017 2016 Assets Investment in consolidated subsidiaries: Bank $ 2,409,098 $ 2,246,060 Non-banks 52,479 51,816 Cash 151,607 51 Securities purchased under agreements to resell — 155,775 Investment securities: Available for sale 53,285 58,051 Non-marketable 655 718 Note receivable due from bank subsidiary 50,000 — Advances to subsidiaries, net of borrowings 14,571 5,053 Income tax benefits 8,279 524 Other assets 19,951 17,716 Total assets $ 2,759,925 $ 2,535,764 Liabilities and stockholders’ equity Pension obligation $ 12,407 $ 17,158 Other liabilities 30,958 22,823 Total liabilities 43,365 39,981 Stockholders’ equity 2,716,560 2,495,783 Total liabilities and stockholders’ equity $ 2,759,925 $ 2,535,764
Condensed Statements Of Income	Condensed Statements of Income For the Years Ended December 31 (In thousands) 2017 2016 2015 Income Dividends received from consolidated bank subsidiary $ 160,002 $ 160,002 $ 160,001 Earnings of consolidated subsidiaries, net of dividends 147,678 118,704 106,636 Interest and dividends on investment securities 2,099 2,364 2,272 Management fees charged to subsidiaries 30,431 30,965 25,713 Investment securities gains 41,717 1,880 — Net interest income on advances and note to subsidiaries 514 21 4 Other 3,346 2,720 1,422 Total income 385,787 316,656 296,048 Expense Salaries and employee benefits 33,714 29,116 22,167 Professional fees 2,036 1,951 1,833 Data processing fees paid to affiliates 3,512 3,226 3,186 Community service 32,093 1,620 991 Other 10,671 9,849 8,278 Total expense 82,026 45,762 36,455 Income tax benefit (15,622 ) (4,497 ) (4,137 ) Net income $ 319,383 $ 275,391 $ 263,730
Condensed Statements Of Cash Flows	Condensed Statements of Cash Flows For the Years Ended December 31 (In thousands ) 2017 2016 2015 Operating Activities Net income $ 319,383 $ 275,391 $ 263,730 Adjustments to reconcile net income to net cash provided by operating activities: Earnings of consolidated subsidiaries, net of dividends (147,678 ) (118,704 ) (106,636 ) Other adjustments, net (11,268 ) 9,541 (1,152 ) Net cash provided by operating activities 160,437 166,228 155,942 Investing Activities (Increase) decrease in securities purchased under agreements to resell 155,775 (51,335 ) 57,210 (Increase) decrease in investment in subsidiaries, net 11 4 (6 ) Proceeds from sales of investment securities 11,006 2,949 — Proceeds from maturities/pay downs of investment securities 2,295 4,105 3,516 Purchases of investment securities — — (2,500 ) Note receivable due from bank subsidiary (50,000 ) — — (Increase) decrease in advances to subsidiaries, net (9,518 ) 13,507 1,171 Net purchases of building improvements and equipment (52 ) (3 ) (113 ) Net cash provided by (used in) investing activities 109,517 (30,773 ) 59,278 Financing Activities Purchases of treasury stock (17,771 ) (39,381 ) (23,176 ) Accelerated share repurchase agreements — — (100,000 ) Issuance of stock under equity compensation plans (8 ) (6 ) 1,914 Cash dividends paid on common stock (91,619 ) (87,070 ) (84,961 ) Cash dividends paid on preferred stock (9,000 ) (9,000 ) (9,000 ) Net cash used in financing activities (118,398 ) (135,457 ) (215,223 ) Increase (decrease) in cash 151,556 (2 ) (3 ) Cash at beginning of year 51 53 56 Cash at end of year $ 151,607 $ 51 $ 53 Income tax payments (receipts), net $ (8,991 ) $ (8,958 ) $ 1,278

Summary of Significant Accoun51

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2017
Buildings [Member]
Property, Plant and Equipment [Line Items]
Depreciable lives for asset, years	30 years
Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Depreciable lives for asset, years	10 years
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciable lives for asset, years	3 years
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciable lives for asset, years	10 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Depreciable lives for asset, years	10 years
Core Deposits [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Core deposit intangibles amortized over useful life, years	8 years
Core Deposits [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Core deposit intangibles amortized over useful life, years	14 years

Summary of Significant Accoun52

Summary of Significant Accounting Policies Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)Locations
Derivative [Line Items]
Locations | Locations	330
Federal Reserve Bank Reserve Requirement	$ 126.1
Cash Held at Federal Reserve Bank	$ 30.6
Amortization period of annual fees on credit card loans, months	12 months
Period past due loans are placed on non-accrual, days	90 days
Consumer loans charged down to fair value, days delinquent	120 days
Period past due credit card loans are charged off, days	180 days
Common stock dividend rate percentage	5.00%
Swaps with Central Clearing Agency [Member] | Cash [Member]
Derivative [Line Items]
Value Of Collateral Posted	$ 12.5

Loans And Allowance For Loan 53

Loans And Allowance For Loan Losses (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Abstract]
Loans To Principal Holders (over 10% ownership in the Company's stock)	$ 0
Unfunded Loan Commitments	10,800,000,000
Unused Approved Credit Card Lines of Credit	5,100,000,000
Loans pledged at the Federal Home Loan Bank as collateral for borrowings and letters of credit obtained to secure public deposits	3,800,000,000
Loans pledged at the Federal Reserve Bank as collateral for discount window borrowings	1,700,000,000
Net Investment in Direct Financing and Sales Type Leases	737,700,000	$ 725,300,000
Capital Leases, Net Investment in Sales Type Leases, Deferred Income	52,100,000	49,900,000
Property Subject to or Available for Operating Lease, Net	17,400,000	19,000,000
Decrease in interest income resulting from modification to credit card loans	(1,000,000)
Commitments to lend additional funds to customers with restructured loans	7,600,000	10,300,000
Loans Held-for-sale, Fair Value Disclosure	15,300,000
Unpaid Principal Balance on Personal Real Estate Loans Held for Sale	14,800,000
Personal Real Estate Loans HFS Past Due	0
Personal Real Estate Loans HFS on Non-Accrual Status	0
Student Loans Held for Sale, Lower of Cost or Fair Value	6,100,000
HFS Student Loans on Non-Accrual Status	0
HFS Student Loans Past Due	0
Foreclosed real estate	681,000	366,000
Personal property acquired in repossession	$ 2,700,000	$ 2,200,000

Loans And Allowance For Loan 54

Loans And Allowance For Loan Losses (Summary Classification Of Held To Maturity Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 13,983,674	$ 13,412,736
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	4,958,554	4,776,365
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	968,820	791,236
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,697,452	2,643,374
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,062,787	2,010,397
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,104,487	1,990,801
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	400,587	413,634
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	783,864	776,465
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 7,123	$ 10,464

Loans And Allowance For Loan 55

Loans And Allowance For Loan Losses Loans And Allowance For Loan Losses (Loans to Directors and Executive Officers) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Loans and Leases Receivable, Related Parties [Roll Forward]
Loans to directors and executive officers, beginning balance	$ 62,991
Additions	655,544
Amounts collected	(639,920)
Amounts written off	0
Loans to directors and executive officers, ending balance	$ 78,615

Loans And Allowance For Loan 56

Loans And Allowance For Loan Losses (Summary Of Activity In The Allowance For Loan Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 155,932	$ 151,532	$ 156,532
Provision for Loan, Lease, and Other Losses	45,244	36,318	28,727
Loans charged off	55,179	50,978	51,050
Less recoveries	13,535	19,060	17,323
Allowance for Loan and Lease Losses Write-offs, Net	41,644	31,918	33,727
Balance at end of period	159,532	155,932	151,532
Commercial Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	91,361	82,086	89,622
Provision for Loan, Lease, and Other Losses	2,327	4,898	(9,319)
Loans charged off	2,538	3,258	4,057
Less recoveries	2,554	7,635	5,840
Allowance for Loan and Lease Losses Write-offs, Net	(16)	(4,377)	(1,783)
Balance at end of period	93,704	91,361	82,086
Personal Banking Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	64,571	69,446	66,910
Provision for Loan, Lease, and Other Losses	42,917	31,420	38,046
Loans charged off	52,641	47,720	46,993
Less recoveries	10,981	11,425	11,483
Allowance for Loan and Lease Losses Write-offs, Net	41,660	36,295	35,510
Balance at end of period	$ 65,828	$ 64,571	$ 69,446

Loans And Allowance For Loan 57

Loans And Allowance For Loan Losses (Allowance For Loan Losses And Related Loan Balance Disaggregated On The Basis Of Impairment Methodology) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Impaired loans, Allowance for loan losses	$ 4,243	$ 3,109
All other loans, Allowance for loan losses	155,289	152,823
Impaired loans, Loans outstanding	114,795	64,532
All other loans, Loans outstanding	13,868,879	13,348,204
Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired loans, Allowance for loan losses	3,067	1,817
All other loans, Allowance for loan losses	90,637	89,544
Impaired loans, Loans outstanding	92,613	44,795
All other loans, Loans outstanding	8,532,213	8,166,180
Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired loans, Allowance for loan losses	1,176	1,292
All other loans, Allowance for loan losses	64,652	63,279
Impaired loans, Loans outstanding	22,182	19,737
All other loans, Loans outstanding	$ 5,336,666	$ 5,182,024

Loans And Allowance For Loan 58

Loans And Allowance For Loan Losses (Investment In Impaired Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Abstract]
Non-accrual loans	$ 11,983	$ 14,283
Restructured loans (accruing)	102,812	50,249
Total impaired loans	$ 114,795	$ 64,532

Loans And Allowance For Loan 59

Loans And Allowance For Loan Losses (Additional Information About Impaired Loans Held) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 114,795,000	$ 64,532,000
Impaired Financing Receivable, Unpaid Principal Balance	122,429,000	73,703,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7,434,000	7,932,000
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	11,120,000	11,222,000
Impaired Financing Receivable, with No Related Allowance, Allowance	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	107,361,000	56,600,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	111,309,000	62,481,000
Impaired Financing Receivable, Related Allowance	4,243,000	3,109,000
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	5,356,000	7,375,000
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,000,000	10,470,000
Impaired Financing Receivable, with No Related Allowance, Allowance	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	72,589,000	29,924,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	73,168,000	31,795,000
Impaired Financing Receivable, Related Allowance	2,455,000	1,318,000
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	557,000
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	752,000
Impaired Financing Receivable, with No Related Allowance, Allowance	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	837,000	69,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	841,000	72,000
Impaired Financing Receivable, Related Allowance	27,000	3,000
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,299,000	0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,303,000	0
Impaired Financing Receivable, with No Related Allowance, Allowance	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	12,532,000	6,870,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	13,071,000	8,072,000
Impaired Financing Receivable, Related Allowance	585,000	496,000
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	9,126,000	6,394,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	11,914,000	9,199,000
Impaired Financing Receivable, Related Allowance	532,000	642,000
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	779,000	0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	817,000	0
Impaired Financing Receivable, with No Related Allowance, Allowance	0	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,388,000	5,281,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,426,000	5,281,000
Impaired Financing Receivable, Related Allowance	67,000	57,000
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	204,000	584,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	204,000	584,000
Impaired Financing Receivable, Related Allowance	11,000	1,000
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,685,000	7,478,000
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	6,685,000	7,478,000
Impaired Financing Receivable, Related Allowance	$ 566,000	$ 592,000

Loans And Allowance For Loan 60

Loans And Allowance For Loan Losses (Total Average Impaired Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Non-accrual loans	$ 13,647	$ 21,429
Restructured loans (accruing)	66,609	49,353
Average impaired loans	80,256	70,782
Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Non-accrual loans	9,658	17,294
Restructured loans (accruing)	49,070	32,295
Average impaired loans	58,728	49,589
Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Non-accrual loans	3,989	4,135
Restructured loans (accruing)	17,539	17,058
Average impaired loans	$ 21,528	$ 21,193

Loans And Allowance For Loan 61

Loans And Allowance For Loan Losses (Interest Income Recognized on Impaired Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	$ 5,082	$ 2,481	$ 2,002
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	3,135	1,064	495
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	41	2	80
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	514	171	122
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	402	152	187
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	307	339	348
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	10	31	20
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Interest income recognized on impaired loans	$ 673	$ 722	$ 750

Loans And Allowance For Loan 62

Loans And Allowance For Loan Losses (Aging Information On Past Due And Accruing Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	$ 13,897,272	$ 13,324,515
30 – 89 Days Past Due	56,292	57,542
90 Days Past Due and Still Accruing	18,127	16,396
Non-accrual	11,983	14,283
Total	13,983,674	13,412,736
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	4,958,554	4,776,365
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	968,820	791,236
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,697,452	2,643,374
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,062,787	2,010,397
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	2,104,487	1,990,801
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	400,587	413,634
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	783,864	776,465
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total	7,123	10,464
Commercial Portfolio Segment [Member] | Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	4,949,148	4,763,274
30 – 89 Days Past Due	3,085	3,735
90 Days Past Due and Still Accruing	374	674
Non-accrual	5,947	8,682
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	967,321	789,633
30 – 89 Days Past Due	1,473	1,039
90 Days Past Due and Still Accruing	21	0
Non-accrual	5	564
Commercial Portfolio Segment [Member] | Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	2,694,234	2,639,586
30 – 89 Days Past Due	482	2,154
90 Days Past Due and Still Accruing	0	0
Non-accrual	2,736	1,634
Personal Banking Portfolio Segment [Member] | Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	2,050,787	1,995,724
30 – 89 Days Past Due	6,218	9,162
90 Days Past Due and Still Accruing	3,321	2,108
Non-accrual	2,461	3,403
Personal Banking Portfolio Segment [Member] | Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	2,067,025	1,957,358
30 – 89 Days Past Due	32,674	29,783
90 Days Past Due and Still Accruing	3,954	3,660
Non-accrual	834	0
Personal Banking Portfolio Segment [Member] | Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	397,349	411,483
30 – 89 Days Past Due	1,962	1,032
90 Days Past Due and Still Accruing	1,276	1,119
Non-accrual	0	0
Personal Banking Portfolio Segment [Member] | Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	764,568	757,443
30 – 89 Days Past Due	10,115	10,187
90 Days Past Due and Still Accruing	9,181	8,835
Non-accrual	0	0
Personal Banking Portfolio Segment [Member] | Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Current or Less than 30 days Past Due	6,840	10,014
30 – 89 Days Past Due	283	450
90 Days Past Due and Still Accruing	0	0
Non-accrual	$ 0	$ 0

Loans And Allowance For Loan 63

Loans And Allowance For Loan Losses (Credit Quality Of Commercial Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	$ 8,624,826	$ 8,210,975
Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	8,288,517	7,939,679
Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	120,368	162,843
Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	207,253	97,573
Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	8,688	10,880
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	4,958,554	4,776,365
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	968,820	791,236
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	2,697,452	2,643,374
Commercial Portfolio Segment [Member] | Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	4,740,013	4,607,553
Commercial Portfolio Segment [Member] | Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	59,177	116,642
Commercial Portfolio Segment [Member] | Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	153,417	43,488
Commercial Portfolio Segment [Member] | Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	5,947	8,682
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	955,499	788,778
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	10,614	722
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	2,702	1,172
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	5	564
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Pass [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	2,593,005	2,543,348
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Special Mention [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	50,577	45,479
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Substandard [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	51,134	52,913
Commercial Portfolio Segment [Member] | Real Estate - Business [Member] | Non-Accrual [Member]
Loans And Allowance For Loan Losses [Line Items]
Commercial Loan Portfolio Gross Carrying Amount	$ 2,736	$ 1,634

Loans And Allowance For Loan 64

Loans And Allowance For Loan Losses (Summary Of Loans In The Personal Banking Portfolio Percentage Of Balances Outstanding ) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Abstract]
Credit Quality Personal Real Estate Loans Excluded	$ 219.2	$ 237.2
Consumer Healthcare Loans Excluded	$ 145	$ 75.4
Credit quality personal banking loan table percentage loans excluded	7.00%
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	100.00%	100.00%
Real Estate - Personal [Member] | Under 600 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	1.30%	1.30%
Real Estate - Personal [Member] | 600 - 659 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	2.10%	2.60%
Real Estate - Personal [Member] | 660 - 719 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	10.50%	10.40%
Real Estate - Personal [Member] | 720 - 779 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	25.60%	25.40%
Real Estate - Personal [Member] | 780 and over [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	60.50%	60.30%
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	100.00%	100.00%
Consumer [Member] | Under 600 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	3.30%	3.40%
Consumer [Member] | 600 - 659 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	5.50%	6.40%
Consumer [Member] | 660 - 719 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	17.30%	19.70%
Consumer [Member] | 720 - 779 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	26.80%	26.30%
Consumer [Member] | 780 and over [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	47.10%	44.20%
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	100.00%	100.00%
Revolving Home Equity [Member] | Under 600 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	1.10%	1.00%
Revolving Home Equity [Member] | 600 - 659 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	1.70%	1.80%
Revolving Home Equity [Member] | 660 - 719 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	9.50%	9.70%
Revolving Home Equity [Member] | 720 - 779 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	21.40%	21.10%
Revolving Home Equity [Member] | 780 and over [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	66.30%	66.40%
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	100.00%	100.00%
Consumer Credit Card [Member] | Under 600 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	4.70%	4.90%
Consumer Credit Card [Member] | 600 - 659 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	14.40%	15.50%
Consumer Credit Card [Member] | 660 - 719 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	34.40%	34.90%
Consumer Credit Card [Member] | 720 - 779 [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	26.00%	25.10%
Consumer Credit Card [Member] | 780 and over [Member]
Loans And Allowance For Loan Losses [Line Items]
Percentage of Loan Category	20.50%	19.60%

Loans And Allowance For Loan 65

Loans And Allowance For Loan Losses (Outstanding Balance Of Loans Classified As Troubled Debt Restructurings) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	$ 110,608	$ 59,074
Balance 90 days past due at any time during previous 12 months	1,031
Commercial Portfolio Segment [Member] | Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	77,400
Balance 90 days past due at any time during previous 12 months	0
Commercial Portfolio Segment [Member] | Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	776
Balance 90 days past due at any time during previous 12 months	0
Commercial Portfolio Segment [Member] | Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	12,394
Balance 90 days past due at any time during previous 12 months	0
Personal Banking Portfolio Segment [Member] | Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	7,760
Balance 90 days past due at any time during previous 12 months	278
Personal Banking Portfolio Segment [Member] | Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	5,389
Balance 90 days past due at any time during previous 12 months	81
Personal Banking Portfolio Segment [Member] | Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	204
Balance 90 days past due at any time during previous 12 months	42
Personal Banking Portfolio Segment [Member] | Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Restructured loans	6,685
Balance 90 days past due at any time during previous 12 months	$ 630

Loans And Allowance For Loan 66

Loans And Allowance For Loan Losses Troubled Debt Restructurings by Type of Modification (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Troubled Debt Restructuring by Type of Modification [Abstract]
Change in troubled debt restructured non-market interest rate loan balance	$ 54,100
Large business loan renewed in current year at non-market rate	31,900
Financing Receivable, Modifications [Line Items]
Restructured loans	110,608	$ 59,074
TDR Non-market interest rates [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	88,588	34,531
TDR Assistance programs [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	6,685	7,478
TDR-Bankruptcy non-affirmation [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	7,283	7,937
TDR Other [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	256	303
TDR Non-accrual loans [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	$ 7,796	$ 8,825

Investment Securities (Narrativ

Investment Securities (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)SecuritiesInvestments_In_Single_Issuer	Dec. 31, 2016USD ($)Securities	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Investment [Line Items]
Non-marketable FHLB and FRB stock held for debt and regulatory purposes	$ 43,300	$ 46,900
Non-marketable private equity investments held	57,200	52,300
U.S. Treasury inflation-protected securities held	$ 442,100
Percentage decrease requiring a review for impairment	20.00%
Fair value of securities on other-than-temporary impairment watch list	$ 68,000	79,600
Cumulative, credit-related portion of impairment (recorded in earnings) on the certain non-agency mortgage-backed securities on the watch list	$ 14,199	$ 14,080	$ 14,129	$ 13,734
Number of individual securities held in the available for sale portfolio | Securities	2,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | Securities	635	771
Portfolio securities aggregate fair value loss position	$ 5,172,412	$ 4,480,405
Available for sale securities in loss position at period end, change in unrealized loss	(16,800)
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	44,122	60,942
Fair value of securities in loss position for twelve months or longer	$ 1,156,715	444,252
Fair value of securities in a loss position for 12 months or longer, as a percentage of total available for sale portfolio	13.20%
Available for sale securities	$ 8,774,280	9,649,203
Securities pledged as collateral	3,800,000	4,400,000
Securities pledged and may be sold or re-pledged	$ 662,500
Number of investments in a single issuer that exceed 10% of stockholder's equity | Investments_In_Single_Issuer	0
No investment in a single issuer exceeds this percentage of stockholder's equity	10.00%
State and municipal obligations [Member]
Investment [Line Items]
Auction rate securities held at fair value	$ 17,000
Portfolio securities aggregate fair value loss position	332,182	715,974
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,754	12,693
Fair value of securities in loss position for twelve months or longer	49,339	15,195
Available for sale securities	$ 1,611,366	1,778,214
State and municipal obligation portfolio, as a percentage of total available for sale securities	18.40%
Equity securities [Member]
Investment [Line Items]
Common stock classified as equity securities held by the holding company	$ 45,900
Available for sale securities	48,838	51,263
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Fair value of securities on other-than-temporary impairment watch list	26,200
Cumulative, credit-related portion of impairment (recorded in earnings) on the certain non-agency mortgage-backed securities on the watch list	14,200
Portfolio securities aggregate fair value loss position	730,830	723,077
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,837	6,493
Fair value of securities in loss position for twelve months or longer	153,813	34,946
Available for sale securities	$ 905,793	$ 1,055,639

Investment Securities (Investme

Investment Securities (Investment Securities, At Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	$ 8,774,280	$ 9,649,203
Trading securities	18,269	22,225
Non-marketable securities	100,758	99,558
Total investment securities	8,893,307	9,770,986
U.S. government and federal agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	917,147	920,904
US Government-sponsored Enterprise Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	406,363	449,998
State and municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	1,611,366	1,778,214
Agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	3,040,913	2,685,931
Non-agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	905,793	1,055,639
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	1,492,800	2,381,301
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	351,060	325,953
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	$ 48,838	$ 51,263

Investment Securities (Summary

Investment Securities (Summary Of Available For Sale Investment Securities By Maturity Groupings) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Amortized Cost		$ 8,719,867	$ 9,600,330
Fair Value		8,774,280	9,649,203
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost		917,494	919,904
Fair Value		$ 917,147	920,904
Weighted Average Yield	[1]	1.24%
U.S. Government And Federal Agency Obligations [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost		$ 57,983
Fair Value		$ 58,347
Weighted Average Yield	[1]	1.71%
U.S. Government And Federal Agency Obligations [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost		$ 641,114
Fair Value		$ 639,192
Weighted Average Yield	[1]	1.45%
U.S. Government And Federal Agency Obligations [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost		$ 149,589
Fair Value		$ 149,927
Weighted Average Yield	[1]	0.43%
U.S. Government And Federal Agency Obligations [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost		$ 68,808
Fair Value		$ 69,681
Weighted Average Yield	[1]	0.59%
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Amortized Cost		$ 408,266	450,448
Fair Value		$ 406,363	449,998
Weighted Average Yield		1.79%
US Government-sponsored Enterprise Debt Securities [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost		$ 215,763
Fair Value		$ 215,434
Weighted Average Yield		1.35%
US Government-sponsored Enterprise Debt Securities [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost		$ 121,575
Fair Value		$ 121,199
Weighted Average Yield		1.93%
US Government-sponsored Enterprise Debt Securities [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost		$ 34,983
Fair Value		$ 34,870
Weighted Average Yield		2.71%
US Government-sponsored Enterprise Debt Securities [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost		$ 35,945
Fair Value		$ 34,860
Weighted Average Yield		3.00%
State and municipal obligations [Member]
Investment [Line Items]
Amortized Cost		$ 1,592,707	1,778,684
Fair Value		$ 1,611,366	1,778,214
Weighted Average Yield		2.39%
State and municipal obligations [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost		$ 164,756
Fair Value		$ 165,638
Weighted Average Yield		2.65%
State and municipal obligations [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost		$ 665,351
Fair Value		$ 670,953
Weighted Average Yield		2.21%
State and municipal obligations [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost		$ 709,248
Fair Value		$ 721,181
Weighted Average Yield		2.46%
State and municipal obligations [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost		$ 53,352
Fair Value		$ 53,594
Weighted Average Yield		3.01%
Agency mortgage-backed securities [Member]
Investment [Line Items]
Amortized Cost		$ 3,046,701	2,674,964
Fair Value		$ 3,040,913	2,685,931
Weighted Average Yield		2.62%
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Amortized Cost		$ 903,920	1,054,446
Fair Value		$ 905,793	1,055,639
Weighted Average Yield		2.54%
Asset-backed Securities [Member]
Investment [Line Items]
Amortized Cost		$ 1,495,380	2,389,176
Fair Value		$ 1,492,800	2,381,301
Weighted Average Yield		2.03%
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Amortized Cost		$ 5,446,001	6,118,586
Fair Value		$ 5,439,506	6,122,871
Weighted Average Yield		2.45%
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost		$ 350,988	327,030
Fair Value		351,060	325,953
Other Debt Securities [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost		10,390
Fair Value		10,389
Other Debt Securities [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost		247,181
Fair Value		247,626
Other Debt Securities [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost		93,417
Fair Value		93,045
Equity securities [Member]
Investment [Line Items]
Amortized Cost		4,411	5,678
Fair Value		$ 48,838	$ 51,263
[1]	Rate does not reflect inflation adjustment on inflation-protected securities

Investment Securities (Availabl

Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Amortized Cost	$ 8,719,867	$ 9,600,330
Available For Sale Securities, Gross Unreailzed Gain at Period End	98,535	109,815
Available For Sale Securities, Gross Unrealized Loss at Period End	(44,122)	(60,942)
Fair Value	8,774,280	9,649,203
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	917,494	919,904
Available For Sale Securities, Gross Unreailzed Gain at Period End	4,096	7,312
Available For Sale Securities, Gross Unrealized Loss at Period End	(4,443)	(6,312)
Fair Value	917,147	920,904
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Amortized Cost	408,266	450,448
Available For Sale Securities, Gross Unreailzed Gain at Period End	26	1,126
Available For Sale Securities, Gross Unrealized Loss at Period End	(1,929)	(1,576)
Fair Value	406,363	449,998
State and municipal obligations [Member]
Investment [Line Items]
Amortized Cost	1,592,707	1,778,684
Available For Sale Securities, Gross Unreailzed Gain at Period End	21,413	12,223
Available For Sale Securities, Gross Unrealized Loss at Period End	(2,754)	(12,693)
Fair Value	1,611,366	1,778,214
Agency mortgage-backed securities [Member]
Investment [Line Items]
Amortized Cost	3,046,701	2,674,964
Available For Sale Securities, Gross Unreailzed Gain at Period End	17,956	31,610
Available For Sale Securities, Gross Unrealized Loss at Period End	(23,744)	(20,643)
Fair Value	3,040,913	2,685,931
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Amortized Cost	903,920	1,054,446
Available For Sale Securities, Gross Unreailzed Gain at Period End	6,710	7,686
Available For Sale Securities, Gross Unrealized Loss at Period End	(4,837)	(6,493)
Fair Value	905,793	1,055,639
Asset-backed Securities [Member]
Investment [Line Items]
Amortized Cost	1,495,380	2,389,176
Available For Sale Securities, Gross Unreailzed Gain at Period End	2,657	3,338
Available For Sale Securities, Gross Unrealized Loss at Period End	(5,237)	(11,213)
Fair Value	1,492,800	2,381,301
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Amortized Cost	5,446,001	6,118,586
Available For Sale Securities, Gross Unreailzed Gain at Period End	27,323	42,634
Available For Sale Securities, Gross Unrealized Loss at Period End	(33,818)	(38,349)
Fair Value	5,439,506	6,122,871
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost	350,988	327,030
Available For Sale Securities, Gross Unreailzed Gain at Period End	1,250	935
Available For Sale Securities, Gross Unrealized Loss at Period End	(1,178)	(2,012)
Fair Value	351,060	325,953
Equity securities [Member]
Investment [Line Items]
Amortized Cost	4,411	5,678
Available For Sale Securities, Gross Unreailzed Gain at Period End	44,427	45,585
Available For Sale Securities, Gross Unrealized Loss at Period End	0	0
Fair Value	$ 48,838	$ 51,263

Investment Securities (Cash Flo

Investment Securities (Cash Flow Model Inputs Used To Calculate Credit Losses) (Details)	Dec. 31, 2017
Minimum [Member]
Investment [Line Items]
Prepayment CPR	0.00%
Projected cumulative default	14.00%
Credit support	0.00%
Loss severity	15.00%
Maximum [Member]
Investment [Line Items]
Prepayment CPR	25.00%
Projected cumulative default	50.00%
Credit support	54.00%
Loss severity	63.00%

Investment Securities (Changes

Investment Securities (Changes In Recorded Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held	$ 14,199	$ 14,080	$ 14,129	$ 13,734
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, No Previous Impairment	111	0	76
Credit losses on debt securities for which impairment was previously recognized	274	270	407
Increase in expected cash flows that are recognized over the remaining life of the security	$ (266)	$ (319)	$ (88)

Investment Securities (Securiti

Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Less than 12 months, Fair Value	$ 4,015,697	$ 4,036,153
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	24,201	50,837
12 months or longer, Fair Value	1,156,715	444,252
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	19,921	10,105
Total, Fair Value	5,172,412	4,480,405
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	44,122	60,942
US Treasury and Government [Member]
Investment [Line Items]
Less than 12 months, Fair Value	618,617	349,538
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,443	2,823
12 months or longer, Fair Value	0	32,208
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	3,489
Total, Fair Value	618,617	381,746
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,443	6,312
US Government-sponsored Enterprise Debt Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	286,393	190,441
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,712	1,576
12 months or longer, Fair Value	49,766	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	217	0
Total, Fair Value	336,159	190,441
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	1,929	1,576
State and municipal obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	282,843	700,779
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,752	12,164
12 months or longer, Fair Value	49,339	15,195
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,002	529
Total, Fair Value	332,182	715,974
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,754	12,693
Agency mortgage-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	1,320,689	1,147,416
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9,433	20,638
12 months or longer, Fair Value	619,300	2,150
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	14,311	5
Total, Fair Value	1,939,989	1,149,566
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	23,744	20,643
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	577,017	688,131
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,966	6,373
12 months or longer, Fair Value	153,813	34,946
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,871	120
Total, Fair Value	730,830	723,077
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,837	6,493
Asset-backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	786,048	780,209
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3,168	5,277
12 months or longer, Fair Value	264,295	358,778
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,069	5,936
Total, Fair Value	1,050,343	1,138,987
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,237	11,213
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	2,683,754	2,615,756
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15,567	32,288
12 months or longer, Fair Value	1,037,408	395,874
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	18,251	6,061
Total, Fair Value	3,721,162	3,011,630
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	33,818	38,349
Other debt securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	144,090	179,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	727	1,986
12 months or longer, Fair Value	20,202	975
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	451	26
Total, Fair Value	164,292	180,614
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 1,178	$ 2,012

Investment Securities Investmen

Investment Securities Investment Securities (Credit Ratings In State And Municipal Bond Portfolio) (Details)	Dec. 31, 2017Rate
Schedule of Available-for-sale Securities [Line Items]
Percentage of State and Municipal Bond Portfolio, by credit rating	100.00%
Moody's, Aaa Rating [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage of State and Municipal Bond Portfolio, by credit rating	6.00%
Moody's Aa Rating [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage of State and Municipal Bond Portfolio, by credit rating	76.90%
Moody's A Rating [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage of State and Municipal Bond Portfolio, by credit rating	16.40%
Moody's Not Rated [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage of State and Municipal Bond Portfolio, by credit rating	0.70%

Investment Securities (Proceeds

Investment Securities (Proceeds From Sales Of Securities And Components Of Investment Securities Gains And Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment [Line Items]
Proceeds from sales of available for sale securities	$ 790,152	$ 2,049	$ 675,870
Proceeds from sales of non-marketable securities	2,228	22,331	13,161
Total proceeds	792,380	24,380	689,031
Investment securities gains (losses), net	25,051	(53)	6,320
Available-for-sale Securities [Member]
Investment [Line Items]
Gains realized on sales	10,656	109	2,925
Loss realized on sales	(10,297)	0	0
Loss Realized on Called Bond	(254)	0	0
Gain realized on donation	31,074	0	0
Other-than-temporary impairment recognized on debt securities	(385)	(270)	(483)
Non-Marketable [Member]
Investment [Line Items]
Gains realized on sales	970	4,349	2,516
Losses realized on sales	(880)	(502)	(40)
Fair value adjustments, net	$ (5,833)	$ (3,739)	$ 1,402

Land, Buildings And Equipment76

Land, Buildings And Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	$ 852,072	$ 886,740
Less accumulated depreciation and amortization	516,962	549,035
Net land, buildings and equipment	335,110	337,705
Depreciation expense	29,100	30,100	$ 30,100
Repairs and maintenance expense	16,400	16,200	16,300
Interest Expense Capitalized on Construction Projects	0	0	$ 0
Land [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	94,992	98,221
Building and improvements [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	540,204	530,489
Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross land, buildings and equipment	$ 216,876	$ 258,030

Goodwill And Other Intangible77

Goodwill And Other Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Impairment of goodwill	$ 0	$ 0	$ 0
Aggregate amortization expense for intangible assets	1,300	1,500	$ 1,800
Goodwill [Member]
Finite-Lived Intangible Assets [Line Items]
Aggregate amortization expense for intangible assets	0	0
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Aggregate amortization expense for intangible assets	876	1,190
Mortgage Servicing Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Recognized temporary impairment	9
Aggregate amortization expense for intangible assets	$ 462	$ 316

Goodwill And Other Intangible78

Goodwill And Other Intangible Assets (Schedule Of Intangible Assets With Estimable Useful Lives) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 39,176	$ 36,942
Accumulated Amortization	(31,549)	(30,211)
Valuation Allowance	(9)	(22)
Net Amount	7,618	6,709
Core Deposit Premium [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	31,270	31,270
Accumulated Amortization	(28,305)	(27,429)
Valuation Allowance	0	0
Net Amount	2,965	3,841
Mortgage Servicing Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,906	5,672
Accumulated Amortization	(3,244)	(2,782)
Valuation Allowance	(9)	(22)
Net Amount	$ 4,653	$ 2,868

Goodwill And Other Intangible79

Goodwill And Other Intangible Assets (Schedule Of Goodwill Allocated By Operating Segments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill	$ 138,921	$ 138,921
Consumer Segment [Member]
Goodwill [Line Items]
Goodwill	70,721	70,721
Commercial Segment [Member]
Goodwill [Line Items]
Goodwill	67,454	67,454
Wealth Segment [Member]
Goodwill [Line Items]
Goodwill	$ 746	$ 746

Goodwill And Other Intangible80

Goodwill And Other Intangible Assets (Schedule Of Changes In Carrying Amount Of Goodwill And Net Other Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Amortization	$ (1,300)	$ (1,500)	$ (1,800)
Goodwill [Member]
Goodwill [Roll Forward]
Balance, beginning	138,921	138,921
Originations	0	0
Amortization	0	0
Impairment reversal	0	0
Balance, ending	138,921	138,921	138,921
Core Deposit Premium [Member]
Goodwill [Roll Forward]
Balance, beginning	3,841	5,031
Originations	0	0
Amortization	(876)	(1,190)
Impairment reversal	0	0
Balance, ending	2,965	3,841	5,031
Mortgage Servicing Rights [Member]
Goodwill [Roll Forward]
Balance, beginning	2,868	1,638
Originations	2,234	1,539
Amortization	(462)	(316)
Impairment reversal	13	7
Balance, ending	$ 4,653	$ 2,868	$ 1,638

Goodwill And Other Intangible81

Goodwill And Other Intangible Assets (Schedule Of Estimated Annual Amortization Expense) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 1,213
2,019	1,038
2,020	878
2,021	753
2,022	$ 653

Deposits (Scheduled Maturities

Deposits (Scheduled Maturities Of Total Time Open And Certificates Of Deposit) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Deposits [Abstract]
Due in 2018	$ 1,414,554
Due in 2019	217,562
Due in 2020	73,192
Due in 2021	41,313
Due in 2022	18,191
Thereafter	2,052
Total	$ 1,766,864

Deposits (Maturities Of Time Op

Deposits (Maturities Of Time Open And Certificates Of Deposit Detailed Breakdown By Size Category) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Deposits [Abstract]
Certificates Of Deposit under $100,000, Due in 3 months or less	$ 115,126
Certificates Of Deposit under $100,000, Due in over 3 through 6 months	115,595
Certificates Of Deposit under $100,000, Due in over 6 through 12 months	180,447
Certificates Of Deposit under $100,000, Due in over 12 months	82,789
Certificates Of Deposit under $100,000	493,957
Other Time Deposits under $100,000, Due in 3 months or less	24,019
Other Time Deposits under $100,000, Due in over 3 through 6 months	26,607
Other Time Deposits under $100,000, Due in over 6 through 12 months	36,573
Other Time Deposits under $100,000, Due in over 12 months	53,490
Other Time Deposits under $100,000	140,689
Certificates Of Deposit over $100,000, Due in 3 months or less	484,168
Certificates Of Deposit over $100,000, Due in over 3 through 6 months	197,173
Certificates Of Deposit over $100,000, Due in over 6 through 12 months	216,459
Certificates Of Deposit over $100,000, Due in over 12 months	205,085
Certificates Of Deposit over $100,000	1,102,885
Other Time Deposits over $100,000, Due in 3 months or less	3,744
Other Time Deposits over $100,000, Due in over 3 through 6 months	5,438
Other Time Deposits over $100,000, Due in over 6 through 12 months	9,205
Other Time Deposits other $100,000, Due in over 12 months	10,946
Other Time Deposits over $100,000	29,333
Due in 3 months or less, Total	627,057
Due in over 3 through 6 months, Total	344,813
Due in over 6 through 12 months, Total	442,684
Due in over 12 months, Total	352,310
Total	1,766,864
Aggregate amount of time open and certificates of deposit that exceed the $250,000 FDIC insurance limit	$ 880,900

Borrowings (Narrative) (Details

Borrowings (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Debt Disclosure [Abstract]
FHLB borrowings repaid	$ 100
FHLB issued letters of credit	498.4
Long-term Debt and Capital Lease Obligations	$ 1.8

Borrowings (Short-Term Borrowin

Borrowings (Short-Term Borrowings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Short-term repurchase agreement comprised of non-insured customer funds	$ 1,300,000
Federal Funds Purchased And Repurchase Agreements [Member]
Short-term Debt [Line Items]
Year End Weighted Rate	0.80%	0.40%	0.20%
Average Weighted Rate	0.70%	0.30%	0.10%
Average Balance Outstanding	$ 1,462,387	$ 1,266,093	$ 1,654,860
Maximum Outstanding at any Month End	1,984,071	1,723,905	2,193,197
Balance at December 31	$ 1,507,138	$ 1,723,905	$ 1,963,552

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Enacted Tax Rate Used to Revalue Deferred Tax Assets and Liabilities	21.00%
Effective income tax rate reconciliation, at federal statutory income tax rate	35.00%	35.00%	35.00%
Unrecognized Tax Benefits	$ 1,208	$ 1,228	$ 1,278
Unrecognized tax benefits impact the effective tax rate	$ 785	$ 798

Income Taxes (Schedule Of Compo

Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. federal, Current	$ 89,154	$ 116,753	$ 102,607
State and local, Current	7,735	9,457	6,551
Current, income tax expense (benefit)	96,889	126,210	109,158
U.S. federal, Deferred	12,190	(2,036)	7,084
State and local, Deferred	1,427	(23)	348
Deferred, income tax expense (benefit)	13,617	(2,059)	7,432
U.S. federal, Total	101,344	114,717	109,691
State and local, Total	9,162	9,434	6,899
Total income tax expense	$ 110,506	$ 124,151	$ 116,590

Income Taxes (Components Of Inc

Income Taxes (Components Of Income Tax Expense Recorded Directly To Stockholders Equity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrealized gain (loss) on securities available for sale	$ 2,104	$ (13,952)	$ (19,634)
Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes	(184)	778	1,478
Accumulated pension (benefit) loss	0	(3,390)	(2,132)
Income tax expense (benefit) allocated to stockholders’ equity	$ 1,920	$ (16,564)	$ (20,288)

Income Taxes (Components Of Def

Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Loans, principally due to allowance for loan losses	$ 40,341	$ 61,233
Equity-based compensation	8,201	12,633
Deferred compensation	5,647	7,998
Private equity investments	5,473	9,667
Accrued expenses	5,245	16,638
Unearned fee income	3,701	3,819
Deferred tax assets, Other	4,430	6,071
Total deferred tax assets	73,038	118,059
Equipment lease financing	45,825	71,355
Unrealized gain on securities available for sale	13,603	18,572
Land, buildings and equipment	8,592	10,375
Undistributed earnings of subsidiaries	7,094	23
Intangibles	5,732	9,105
Deferred tax liabilities, Other	6,569	8,765
Total deferred tax liabilities	87,415	118,195
Net deferred tax assets (liabilities)	$ (14,377)	$ (136)

Income Taxes (Schedule Of Compa

Income Taxes (Schedule Of Company's Actual Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Computed “expected” tax expense	$ 150,461	$ 139,840	$ 133,112
Tax-exempt interest, net of cost to carry	(20,295)	(20,033)	(19,083)
Effective Income Tax Rate Reconciliation, Contribution of Appreciated Securities, Amount	(10,864)	0	0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(6,753)	0	0
Effective Income Tax Rate Reconciliation, Share-based Award Payments, Amount	(6,613)	0	0
State and local income taxes, net of federal tax benefit	5,955	6,132	4,484
Tax deductible dividends on allocated shares held by the Company’s ESOP	(966)	(1,044)	(1,093)
Other	(419)	(744)	(830)
Total income tax expense	$ 110,506	$ 124,151	$ 116,590

Income Taxes (Schedule Of Accru

Income Taxes (Schedule Of Accrued Liability For Unrecognized Tax Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	$ 1,228	$ 1,278
Gross increases – tax positions in prior period	5	0
Gross decreases – tax positions in prior period	0	(1)
Gross increases – current-period tax positions	268	269
Lapse of statute of limitations	(293)	(318)
Unrecognized tax benefits at end of year	$ 1,208	$ 1,228

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, discretionary contribution by employer	$ 5,500,000	$ 0
Minimum required contribution for 2017	0
Contributions to the CERP	439,000	21,000	$ 20,000
Accumulated benefit obligation	120,700,000	116,700,000
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	2,100,000
Interest cost on projected benefit obligation	$ 3,826,000	$ 3,944,000	$ 4,762,000
Expected long-term rate of return on pension plan assets	6.00%	6.00%	6.00%
Annualized 10-year return for pension plan	6.30%
Rate of return	9.60%	7.20%
Pension expense	$ 704,000
Expected pension expense for the upcoming fiscal year	$ 761,000
Equity securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term investment target mix	35.00%
Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term investment target mix	65.00%
Change due to updated mortality projection scale [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Change in pension plan obligations due to change in mortality assumptions	$ (300,000)
Change in Accounting Estimate, Type [Domain]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost on projected benefit obligation		$ (900,000)

Employee Benefit Plans (Employe

Employee Benefit Plans (Employee Benefits Charged To Operating Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total employee benefits	$ 67,376	$ 66,470	$ 60,180
Payroll Taxes [Member]
Total employee benefits	24,402	23,210	22,235
Medical Plans [Member]
Total employee benefits	25,143	25,497	20,659
401K Plan [Member]
Total employee benefits	14,244	13,562	12,841
Pension Plans [Member]
Total employee benefits	704	987	1,495
Other [Member]
Total employee benefits	$ 2,883	$ 3,214	$ 2,950

Employee Benefit Plans (Compone

Employee Benefit Plans (Components Of The Net Pension Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Service cost-benefits earned during the year	$ 621	$ 500	$ 503
Interest cost on projected benefit obligation	3,826	3,944	4,762
Expected return on plan assets	(5,785)	(5,751)	(6,092)
Amortization of Prior Service Cost (Credit)	(271)	(271)	(271)
Amortization of unrecognized net loss	2,313	2,565	2,593
Net periodic pension cost	$ 704	$ 987	$ 1,495

Employee Benefit Plans (Summary

Employee Benefit Plans (Summary Of Pension Plans Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at prior valuation date	$ 116,695	$ 117,562
Service cost	621	500	$ 503
Interest cost	3,826	3,944	4,762
Benefits paid	(6,780)	(6,322)
Actuarial (gain) loss	6,305	1,011
Projected benefit obligation at valuation date	120,667	116,695	117,562
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at prior valuation date	99,537	99,325
Actual return on plan assets	9,564	6,513
Employer contributions	5,939	21
Benefits paid	(6,780)	(6,322)
Fair value of plan assets at valuation date	108,260	99,537	$ 99,325
Funded status and net amount recognized at valuation date	$ (12,407)	$ (17,158)

Employee Benefit Plans (Schedul

Employee Benefit Plans (Schedule Of Amounts Not Yet Reflected In Net Periodic Benefit Cost And Included In Accumulated Other Comprehensive Income (Loss), Pre-Tax Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Prior service credit (cost)	$ 1,806	$ 2,077
Accumulated loss	(33,499)	(33,285)
Accumulated other comprehensive loss	(31,693)	(31,208)
Cumulative employer contributions in excess of net periodic benefit cost	19,286	14,050
Net amount recognized as an accrued benefit liability on the December 31 balance sheet	(12,407)	(17,158)
Net loss arising during period	(2,527)	(248)
Amortization or settlement recognition of net loss	2,313	2,565
Amortization of Prior Service Cost (Credit)	(271)	(271)	$ (271)
Total recognized in other comprehensive income	(485)	2,046
Total expense recognized in net periodic pension cost and other comprehensive income	$ (1,189)	$ 1,059

Employee Benefit Plans (Assumpt

Employee Benefit Plans (Assumptions On A Weighted Average Basis, Used In Accounting For Plans) (Details)	12 Months Ended
	Dec. 31, 2017Rate	Dec. 31, 2016Rate	Dec. 31, 2015Rate
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Determination of benefit obligation at year end, Discount rate	3.57%	4.05%	4.15%
Determination of benefit obligation at year end, Assumed credit on cash balance accounts	5.00%	5.00%	5.00%
Determination of net periodic benefit cost for year ended, Discount rate	3.95%	4.16%	3.95%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Effective Rate of Interest	3.28%	3.38%
Determination of net periodic benefit cost for year ended, Long-term rate of return on assets	6.00%	6.00%	6.00%
Determination of net periodic benefit cost for year ended, Assumed credit on cash balance accounts	5.00%	5.00%	5.00%

Employee Benefit Plans (Fair Va

Employee Benefit Plans (Fair Value Of Pension Plan Assets By Asset Category) (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
U.S. government obligations		$ 917,147	$ 920,904
Government-sponsored enterprise obligations		406,363	449,998
State and municipal obligations		1,611,366	1,778,214
Agency mortgage-backed securities		3,040,913	2,685,931
Non-agency mortgage-backed securities		905,793	1,055,639
Asset-backed securities		1,492,800	2,381,301
Pension Plans [Member]
U.S. government obligations		3,719	3,621
Government-sponsored enterprise obligations	[1]	1,282	1,215
State and municipal obligations		8,527	9,148
Agency mortgage-backed securities	[2]	7,896	4,073
Non-agency mortgage-backed securities		4,891	5,437
Asset-backed securities		3,833	5,275
Corporate bonds	[3]	37,457	34,037
Mutual funds	[4]	6,979	10,393
Common stocks	[4]	23,744	20,141
International developed markets	[4]	7,870	5,100
Emerging markets	[4]	2,062	1,097
Total		108,260	99,537
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
U.S. government obligations		917,147	920,904
Government-sponsored enterprise obligations		0	0
State and municipal obligations		0	0
Agency mortgage-backed securities		0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Pension Plans [Member]
U.S. government obligations		3,719	3,621
Government-sponsored enterprise obligations	[1]	0	0
State and municipal obligations		0	0
Agency mortgage-backed securities	[2]	0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Corporate bonds	[3]	0	0
Mutual funds	[4]	6,979	10,393
Common stocks	[4]	23,744	20,141
International developed markets	[4]	7,870	5,100
Emerging markets	[4]	2,062	1,097
Total		44,374	40,352
Significant Other Observable Inputs (Level 2) [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations		406,363	449,998
State and municipal obligations		1,594,350	1,761,532
Agency mortgage-backed securities		3,040,913	2,685,931
Non-agency mortgage-backed securities		905,793	1,055,639
Asset-backed securities		1,492,800	2,381,301
Significant Other Observable Inputs (Level 2) [Member] | Pension Plans [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations	[1]	1,282	1,215
State and municipal obligations		8,527	9,148
Agency mortgage-backed securities	[2]	7,896	4,073
Non-agency mortgage-backed securities		4,891	5,437
Asset-backed securities		3,833	5,275
Corporate bonds	[3]	37,457	34,037
Mutual funds	[4]	0	0
Common stocks	[4]	0	0
International developed markets	[4]	0	0
Emerging markets	[4]	0	0
Total		63,886	59,185
Significant Unobservable Inputs (Level 3) [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations		0	0
State and municipal obligations		17,016	16,682
Agency mortgage-backed securities		0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Significant Unobservable Inputs (Level 3) [Member] | Pension Plans [Member]
U.S. government obligations		0	0
Government-sponsored enterprise obligations	[1]	0	0
State and municipal obligations		0	0
Agency mortgage-backed securities	[2]	0	0
Non-agency mortgage-backed securities		0	0
Asset-backed securities		0	0
Corporate bonds	[3]	0	0
Mutual funds	[4]	0	0
Common stocks	[4]	0	0
International developed markets	[4]	0	0
Emerging markets	[4]	0	0
Total		$ 0	$ 0
[1]	This category represents bonds (excluding mortgage-backed securities) issued by agencies such as the Federal Home Loan Bank, the Federal Home Loan Mortgage Corp and the Federal National Mortgage Association.
[2]	This category represents mortgage-backed securities issued by the agencies mentioned in (a).
[3]	This category represents investment grade bonds issued in the U.S., primarily by domestic issuers, representing diverse industries.
[4]	This category represents investments in individual common stocks and equity funds. These holdings are diversified, largely across the financial services, consumer goods, healthcare, electronic technology and technology services industries.

Employee Benefit Plans (Future

Employee Benefit Plans (Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
2,018	$ 7,133
2,019	7,231
2,020	7,413
2,021	7,534
2,022	7,473
2023 - 2027	$ 37,421

Stock-Based Compensation and100

Stock-Based Compensation and Directors Stock Purchase Plan (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining number of shares available for issuance under the plan	2,776,076
Stock-based compensation	$ 12.1	$ 11.5	$ 10.1
Total tax benefit recognized from compensation arrangements	4.5	4.3	3.8
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets				$ 1.3
Fair value of shares vested during the period	23.8	$ 10.9	$ 6
Unrecognized compensation cost related to unvested options, SAR's and stock awards	$ 24
Compensation cost is expected to be recognized over a weighted average period, years	3 years
Common stock dividend rate percentage	5.00%
Nonvested Stock Award [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period (in years)	4 years
Nonvested Stock Award [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period (in years)	7 years
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period (in years)	4 years
Contractual terms of awards granted (in years)	10 years
Directors Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining number of shares available for issuance under the plan	80,377
Number of shares purchased under stock option plan	15,873	21,568
Average price of shares purchased under stock option plan	$ 54.55	$ 42.50

Stock-Based Compensation and101

Stock-Based Compensation and Directors Stock Purchase Plan (Summary Of The Status Of Nonvested Share Awards) (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Nonvested Share Awards [Roll Forward]
Nonvested, share awards, beginning balance | shares	1,461,713
Granted, Shares | shares	263,123
Vested, Shares | shares	(442,435)
Forfeited, Shares | shares	(27,883)
Canceled, Shares | shares	0
Nonvested, share awards, ending balance | shares	1,254,518
Nonvested Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested, Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 33.02
Granted, Weighted Average Grant Date Fair Value | $ / shares	54.56
Vested, Weighted Average Grant Date Fair Value | $ / shares	29.41
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	39.12
Canceled, Weighted Average Grant Date Fair Value | $ / shares	0
Nonvested , Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 38.67

Stock-Based Compensation and102

Stock-Based Compensation and Directors Stock Purchase Plan (Summary Of SAR Activity) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Stock Appreciation Rights, Shares [Roll Forward]
Outstanding, Shares, Beginning Balance | shares	1,390,782
Granted, Shares | shares	173,740
Forfeited, Shares | shares	(13,325)
Expired, Shares | shares	(878)
Exercised, Shares | shares	(371,033)
Outstanding, Shares, Ending Balance | shares	1,179,286
Exercisable, Shares, Ending Balance | shares	630,135
Stock Appreciation Rights, Weighted Average Exercise Price [Roll Forward]
Outstanding, Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 32.89
Granted, Weighted Average Exercise Price | $ / shares	54.79
Forfeited, Weighted Average Exercise Price | $ / shares	42.19
Expired, Weighted Average Exercise Price | $ / shares	34.75
Exercised, Weighted Average Exercise Price | $ / shares	29.30
Outstanding, Weighted Average Exercise Price, Ending Balance | $ / shares	37.13
Exercisable, Weighted Average Exercise Price, Ending Balance | $ / shares	$ 32.60
Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 2 months
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding | $	$ 22,073
Exercisable, Weighted Average Remaining Contractual Term (in years)	4 years 7 months
Exercisable, Aggregate Intrinsic Value, Ending Balance | $	$ 14,645

Stock-Based Compensation and103

Stock-Based Compensation and Directors Stock Purchase Plan Share Based Compensation Valuation Assumptions [Table] (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 11.94	$ 6.79	$ 6.55
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	1.60%	2.20%	2.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	21.10%	21.20%	21.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.40%	1.80%	1.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	7 years	7 years 2 months	7 years 2 months

Stock-Based Compensation and104

Stock-Based Compensation and Directors Stock Purchase Plan Stock-Based Compensation and Directors Stock Purchase Plan (Additional Information About Stock Options and SARs Exercises) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation [Abstract]
Intrinsic value of options and SARs exercised	$ 9,310	$ 8,854	$ 7,541
Cash received from options and SARs exercised	0	0	1,914
Tax benefit realized from options and SARs exercised	$ 2,698	$ 1,781	$ 1,041

Accumulated Other Comprehens105

Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income		$ 14,108,000	$ 10,975,000	$ 32,470,000
Other Comprehensive Income (Loss), before Reclassifications, before Tax		34,059,000	(37,125,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		(29,006,000)	2,456,000
Other Comprehensive Income (Loss), before Tax		5,053,000	(34,669,000)
Other Comprehensive Income (Loss), Tax		(1,920,000)	13,174,000
Other comprehensive income (loss)		3,133,000	(21,495,000)	(29,623,000)
Reclassification Where Impairment Was Not Previously Recognized		0
Pension Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	[1]	(19,629,000)	(19,328,000)	(20,596,000)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[1]	(2,527,000)	(248,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[1]	2,042,000	2,294,000
Other Comprehensive Income (Loss), before Tax	[1]	(485,000)	2,046,000
Other Comprehensive Income (Loss), Tax	[1]	184,000	(778,000)
Other comprehensive income (loss)	[1]	(301,000)	1,268,000
Reclassification Where Impairment Was Not Previously Recognized	[1]	0	0
Unrealized Gain Loss on Securities Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	[2]	30,326,000	27,328,000	49,750,000
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[2]	36,307,000	(36,057,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[2]	(31,433,000)	(108,000)
Other Comprehensive Income (Loss), before Tax	[2]	4,874,000	(36,165,000)
Other Comprehensive Income (Loss), Tax	[2]	(1,852,000)	13,743,000
Other comprehensive income (loss)	[2]	3,022,000	(22,422,000)
Reclassification Where Impairment Was Not Previously Recognized	[2]	(24,000)	0
Unrealized Gain Loss on Securities OTTI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	[2]	3,411,000	2,975,000	$ 3,316,000
Other Comprehensive Income (Loss), before Reclassifications, before Tax	[2]	279,000	(820,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[2]	385,000	270,000
Other Comprehensive Income (Loss), before Tax	[2]	664,000	(550,000)
Other Comprehensive Income (Loss), Tax	[2]	(252,000)	209,000
Other comprehensive income (loss)	[2]	412,000	(341,000)
Reclassification Where Impairment Was Not Previously Recognized	[2]	$ 24,000	$ 0
[1]	The pre-tax amounts reclassified from accumulated other comprehensive income are included in the computation of net periodic pension cost as "amortization of prior service cost" and "amortization of unrecognized net loss" (see Note 9), for inclusion in the consolidated statements of income.
[2]	The pre-tax amounts reclassified from accumulated other comprehensive income are included in "investment securities gains (losses), net" in the consolidated statements of income.

Segments (Schedule Of Financial

Segments (Schedule Of Financial Information By Segment) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Operating_Segments	Dec. 31, 2016USD ($)Operating_Segments	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Operating_Segments	3	3
Net interest income	$ 733,679	$ 680,049	$ 634,320
Provision for loan losses	(45,244)	(36,318)	(28,727)
Non-interest income	486,604	474,392	448,139
Investment securities gains (losses), net	25,051	(53)	6,320
Non-interest expense	(769,684)	(717,065)	(676,487)
Income before income taxes	430,406	401,005	383,565
Consumer Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	279,031	268,654	266,328
Provision for loan losses	(41,829)	(36,042)	(34,864)
Non-interest income	136,554	131,988	119,561
Investment securities gains (losses), net	0	0	0
Non-interest expense	(290,905)	(282,061)	(273,378)
Income before income taxes	82,851	82,539	77,647
Commercial Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	328,345	311,704	296,510
Provision for loan losses	205	4,378	1,032
Non-interest income	194,581	199,384	194,133
Investment securities gains (losses), net	0	0	0
Non-interest expense	(290,874)	(284,432)	(267,343)
Income before income taxes	232,257	231,034	224,332
Wealth Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	47,264	44,113	42,653
Provision for loan losses	(41)	(122)	75
Non-interest income	158,175	144,661	136,374
Investment securities gains (losses), net	0	0	0
Non-interest expense	(120,458)	(113,888)	(108,755)
Income before income taxes	84,940	74,764	70,347
Segment Totals [Member]
Segment Reporting Information [Line Items]
Net interest income	654,640	624,471	605,491
Provision for loan losses	(41,665)	(31,786)	(33,757)
Non-interest income	489,310	476,033	450,068
Investment securities gains (losses), net	0	0	0
Non-interest expense	(702,237)	(680,381)	(649,476)
Income before income taxes	400,048	388,337	372,326
Other/Elimination [Member]
Segment Reporting Information [Line Items]
Net interest income	79,039	55,578	28,829
Provision for loan losses	(3,579)	(4,532)	5,030
Non-interest income	(2,706)	(1,641)	(1,929)
Investment securities gains (losses), net	25,051	(53)	6,320
Non-interest expense	(67,447)	(36,684)	(27,011)
Income before income taxes	$ 30,358	$ 12,668	$ 11,239

Segments Segments (Segment Bala

Segments Segments (Segment Balance Sheet Data) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Average Assets	$ 25,031,608	$ 24,556,471
Average Loans, including held for sale	13,629,151	12,953,488
Average Goodwill and other intangible assets	146,018	145,565
Average Deposits	20,594,786	20,330,913
Consumer Segment [Member]
Segment Reporting Information [Line Items]
Average Assets	2,610,045	2,673,915
Average Loans, including held for sale	2,471,578	2,533,528
Average Goodwill and other intangible assets	76,734	75,971
Average Deposits	10,190,613	9,956,327
Commercial Segment [Member]
Segment Reporting Information [Line Items]
Average Assets	8,830,584	8,267,963
Average Loans, including held for sale	8,635,035	8,072,528
Average Goodwill and other intangible assets	68,538	68,848
Average Deposits	8,301,004	8,243,394
Wealth Segment [Member]
Segment Reporting Information [Line Items]
Average Assets	1,218,598	1,116,969
Average Loans, including held for sale	1,209,792	1,108,211
Average Goodwill and other intangible assets	746	746
Average Deposits	2,090,582	2,084,940
Segment Totals [Member]
Segment Reporting Information [Line Items]
Average Assets	12,659,227	12,058,847
Average Loans, including held for sale	12,316,405	11,714,267
Average Goodwill and other intangible assets	146,018	145,565
Average Deposits	20,582,199	20,284,661
Other/Elimination [Member]
Segment Reporting Information [Line Items]
Average Assets	12,372,381	12,497,624
Average Loans, including held for sale	1,312,746	1,239,221
Average Goodwill and other intangible assets	0	0
Average Deposits	$ 12,587	$ 46,252

Common and Preferred Stock (Nar

Common and Preferred Stock (Narrative) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, shares authorized	120,000,000	120,000,000
Common stock dividend rate percentage	5.00%
Common stock, par value	$ 5	$ 5
Antidilutive Securities Excluded from Computation of Earnings Per Share (in shares)	152,000	99,000	443,000
Shares available for purchase under the current Board authorization			5,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	3,443,523

Common and Preferred Stock (Sum

Common and Preferred Stock (Summary Of Components Used To Calculate Basic And Diluted Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Commerce Bancshares, Inc.	$ 319,383	$ 275,391	$ 263,730
Preferred Stock Dividends, Income Statement Impact	9,000	9,000	9,000
Net Income (Loss) Available to Common Stockholders, Basic	$ 310,383	$ 266,391	$ 254,730
Basic income per common share (in dollars per share)	$ 2.90	$ 2.50	$ 2.33
Diluted income per common share (in dollars per share)	$ 2.89	$ 2.49	$ 2.32
Basic Income Per Common Share [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Commerce Bancshares, Inc.	$ 319,383	$ 275,391	$ 263,730
Preferred Stock Dividends, Income Statement Impact	9,000	9,000	9,000
Net Income (Loss) Available to Common Stockholders, Basic	310,383	266,391	254,730
Less income allocated to nonvested restricted stockholders	3,848	3,698	3,548
Net income available to common stockholders	$ 306,535	$ 262,693	$ 251,182
Weighted average common shares outstanding	105,555	105,243	108,016
Basic income per common share (in dollars per share)	$ 2.90	$ 2.50	$ 2.33
Diluted Income Per Common Share [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders, Diluted	$ 310,383	$ 266,391	$ 254,730
Less income allocated to nonvested restricted stockholders	3,838	3,692	3,541
Net income available to common stockholders	$ 306,545	$ 262,699	$ 251,189
Weighted average common shares outstanding	105,555	105,243	108,016
Net effect of the assumed exercise of stock-based awards -- based on the treasury stock method using the average market price for the respective periods	372	281	336
Weighted average diluted common shares outstanding	105,927	105,524	108,352
Diluted income per common share (in dollars per share)	$ 2.89	$ 2.49	$ 2.32

Common and Preferred Stock Comm

Common and Preferred Stock Common and Preferred Stock (Schedule of Activity in the Outstanding Shares of the Company's Common Stock) (Details) - Common Stock [Member] - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Common Stock [Roll Forward]
Shares outstanding, beginning balance	101,461	97,226	96,327
Awards and sales under employee and director plans	403	397	435
5% stock dividend	5,078	4,831	4,641
Purchases of treasury stock under accelerated share buyback programs	0	0	(3,635)
Other purchases of treasury stock	(315)	(959)	(535)
Other	(12)	(34)	(7)
Shares outstanding, ending balance	106,615	101,461	97,226

Common and Preferred Stock Pref

Common and Preferred Stock Preferred Stock Issuance (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Jun. 19, 2014
Preferred Stock Issuance [Abstract]
Depositary shares issued	6,000,000
Preferred stock, shares issued	6,000	6,000	6,000
Preferred stock, par value	$ 1	$ 1	$ 1
Preferred Stock, Liquidation Preference, Value	$ 150
Preferred Stock, Liquidation Preference Per Share	$ 25

Common and Preferred Stock Acce

Common and Preferred Stock Accelerated Share Repurchase (Details) - USD ($) shares in Millions, $ in Millions	May 21, 2015	Jun. 20, 2014	Dec. 31, 2015
Accelerated Share Repurchase [Abstract]
Accelerated Share Repurchase Program Repurchase Amount	$ 100	$ 200
Shares received under accelerated share repurchase program			7.9

Regulatory Capital Requireme113

Regulatory Capital Requirements (Schedule Of Capital Amounts And Ratios On Consolidated Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	10.00%
Tier I Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	8.00%
Tier I Common Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	6.50%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Ratio	5.00%
Commerce Bancshares, Inc. (Consolidated) [Member]
Total Capital (to risk-weighted assets), Actual Amount	$ 2,747,863	$ 2,529,675
Total Capital (to risk-weighted assets), Actual Ratio	14.35%	13.32%
Total Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,531,996	$ 1,519,578
Total Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Tier I Capital (to risk-weighted assets), Actual Amount	$ 2,567,264	$ 2,352,154
Tier I Capital (to risk-weighted assets), Actual Ratio	13.41%	12.38%
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,148,997	$ 1,139,684
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	6.00%	6.00%
Tier I Common Capital (to risk-weighted assets), Actual Amount	$ 2,422,480	$ 2,207,370
Tier I Common Capital (to rIsk-weighted assets), Actual Rato	12.65%	11.62%
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 861,748	$ 854,763
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	4.50%	4.50%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Amount	$ 2,567,264	$ 2,352,154
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Ratio	10.39%	9.55%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Amount	$ 988,653	$ 985,698
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Ratio	4.00%	4.00%
Commerce Bank [Member]
Total Capital (to risk-weighted assets), Actual Amount	$ 2,428,789	$ 2,268,845
Total Capital (to risk-weighted assets), Actual Ratio	12.76%	12.00%
Total Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,522,361	$ 1,512,471
Total Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Amount	$ 1,902,951	$ 1,890,589
Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	10.00%	10.00%
Tier I Capital (to risk-weighted assets), Actual Amount	$ 2,268,131	$ 2,111,797
Tier I Capital (to risk-weighted assets), Actual Ratio	11.92%	11.17%
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,141,771	$ 1,134,353
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	6.00%	6.00%
Tier I Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Amount	$ 1,522,361	$ 1,512,471
Tier I Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	8.00%	8.00%
Tier I Common Capital (to risk-weighted assets), Actual Amount	$ 2,268,131	$ 2,111,797
Tier I Common Capital (to rIsk-weighted assets), Actual Rato	11.92%	11.17%
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 856,328	$ 850,765
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	4.50%	4.50%
Tier I Common Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Amount	$ 1,236,918	$ 1,228,883
Tier I Common Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	6.50%	6.50%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Amount	$ 2,268,131	$ 2,111,797
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Ratio	9.20%	8.59%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Amount	$ 986,240	$ 983,081
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Ratio	4.00%	4.00%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Amount	$ 1,232,800	$ 1,228,851
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Ratio	5.00%	5.00%

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Private equity investments, included in non-marketable securities	$ 55,752	$ 50,820
Fair Value Hierarchy, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Auction rate securities, available for sale	17,000
Private equity investments, included in non-marketable securities	$ 55,752	$ 50,820

Fair Value Measurements (Summar

Fair Value Measurements (Summary Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	$ 15,327	$ 9,263
U.S. government and federal agency obligations	917,147	920,904
Government-sponsored enterprise obligations	406,363	449,998
State and municipal obligations	1,611,366	1,778,214
Agency mortgage-backed securities	3,040,913	2,685,931
Non-agency mortgage-backed securities	905,793	1,055,639
Asset-backed securities	1,492,800	2,381,301
Other debt securities	351,060	325,953
Equity securities	48,838	51,263
Trading securities	18,269	22,225
Private equity investments	55,752	50,820
Derivative Assets	8,349	13,566
Deferred Compensation Plan Assets	12,843	10,261
Total assets	8,884,820	9,755,338
Derivative Liability	8,074	13,339
Deferred Compensation Liability, Current and Noncurrent	12,843	10,261
Total liabilities	20,917	23,600
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
U.S. government and federal agency obligations	917,147	920,904
Government-sponsored enterprise obligations	0	0
State and municipal obligations	0	0
Agency mortgage-backed securities	0	0
Non-agency mortgage-backed securities	0	0
Asset-backed securities	0	0
Other debt securities	0	0
Equity securities	19,864	24,967
Trading securities	0	0
Private equity investments	0	0
Derivative Assets	0	0
Deferred Compensation Plan Assets	12,843	10,261
Total assets	949,854	956,132
Derivative Liability	0	0
Deferred Compensation Liability, Current and Noncurrent	12,843	10,261
Total liabilities	12,843	10,261
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	15,327	9,263
U.S. government and federal agency obligations	0	0
Government-sponsored enterprise obligations	406,363	449,998
State and municipal obligations	1,594,350	1,761,532
Agency mortgage-backed securities	3,040,913	2,685,931
Non-agency mortgage-backed securities	905,793	1,055,639
Asset-backed securities	1,492,800	2,381,301
Other debt securities	351,060	325,953
Equity securities	28,974	26,296
Trading securities	18,269	22,225
Private equity investments	0	0
Derivative Assets	7,723	13,146
Deferred Compensation Plan Assets	0	0
Total assets	7,861,572	8,731,284
Derivative Liability	7,951	13,177
Deferred Compensation Liability, Current and Noncurrent	0	0
Total liabilities	7,951	13,177
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
U.S. government and federal agency obligations	0	0
Government-sponsored enterprise obligations	0	0
State and municipal obligations	17,016	16,682
Agency mortgage-backed securities	0	0
Non-agency mortgage-backed securities	0	0
Asset-backed securities	0	0
Other debt securities	0	0
Equity securities	0	0
Trading securities	0	0
Private equity investments	55,752	50,820
Derivative Assets	626	420
Deferred Compensation Plan Assets	0	0
Total assets	73,394	67,922
Derivative Liability	123	162
Deferred Compensation Liability, Current and Noncurrent	0	0
Total liabilities	$ 123	$ 162

Fair Value Measurements (Sum116

Fair Value Measurements (Summary of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	$ 67,760	$ 80,296
Total gains or losses (realized/unrealized) included in earnings	(5,567)	(3,696)
Total gains losses (realized/unrealized) included in other comprehensive income	882	583
Investment securities called	(600)	(1,200)
Discount accretion	52	104
Purchases of private equity securities	13,352	9,906
Sale / paydown of private equity securities	(2,621)	(18,471)
Capitalized interest/dividends	34	92
Purchase of risk participation agreement	70	404
Sale of risk participation agreement	(91)	(258)
Ending balance	73,271	67,760
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	(5,043)	(5,608)
State and Municipal Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	16,682	17,195
Total gains or losses (realized/unrealized) included in earnings	0	0
Total gains losses (realized/unrealized) included in other comprehensive income	882	583
Investment securities called	(600)	(1,200)
Discount accretion	52	104
Purchases of private equity securities	0	0
Sale / paydown of private equity securities	0	0
Capitalized interest/dividends	0	0
Purchase of risk participation agreement	0	0
Sale of risk participation agreement	0	0
Ending balance	17,016	16,682
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	0	0
Private Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	50,820	63,032
Total gains or losses (realized/unrealized) included in earnings	(5,833)	(3,739)
Total gains losses (realized/unrealized) included in other comprehensive income	0	0
Investment securities called	0	0
Discount accretion	0	0
Purchases of private equity securities	13,352	9,906
Sale / paydown of private equity securities	(2,621)	(18,471)
Capitalized interest/dividends	34	92
Purchase of risk participation agreement	0	0
Sale of risk participation agreement	0	0
Ending balance	55,752	50,820
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	(5,658)	(5,914)
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	258	69
Total gains or losses (realized/unrealized) included in earnings	266	43
Total gains losses (realized/unrealized) included in other comprehensive income	0	0
Investment securities called	0	0
Discount accretion	0	0
Purchases of private equity securities	0	0
Sale / paydown of private equity securities	0	0
Capitalized interest/dividends	0	0
Purchase of risk participation agreement	70	404
Sale of risk participation agreement	(91)	(258)
Ending balance	503	258
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	$ 615	$ 306

Fair Value Measurements (Sum117

Fair Value Measurements (Summary of Gains and Losses on Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	$ (5,567)	$ (3,696)
Change in unrealized gains or losses relating to assets still held at period end	(5,043)	(5,608)
Loans Fees And Sales [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	231	87
Change in unrealized gains or losses relating to assets still held at period end	580	350
Other Non-Interest Income [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	35	(44)
Change in unrealized gains or losses relating to assets still held at period end	35	(44)
Investment Securities Gains (Losses), Net [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Total gains or losses included in earnings	(5,833)	(3,739)
Change in unrealized gains or losses relating to assets still held at period end	$ (5,658)	$ (5,914)

Fair Value Measurements (Sum118

Fair Value Measurements (Summary of Quantitative Information About Level 3 Fair Value Measurements) (Details)	12 Months Ended
	Dec. 31, 2017
Auction Rate Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Discounted Cash Flow, Valuation Techniques	Discounted cash flow
Fair Value, Estimated Market Recovery Period, Years	5 years
Private Equity Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Market Comparable Companies, Valuation Techniques	Market comparable companies
Mortgage Loan Commitments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Discounted Cash Flow, Valuation Techniques	Discounted cash flow
Minimum [Member] | Auction Rate Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Estimated Market Rate, Percent	3.10%
Minimum [Member] | Private Equity Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Inputs, Earnings before Interest, Taxes, Depreciation, and Amortization Multiple	4
Minimum [Member] | Mortgage Loan Commitments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Probability of Funding	50.40%
Embedded Servicing Value, Mortgage Loan Commitments, Discounted Cash Flow	(0.30%)
Maximum [Member] | Auction Rate Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Estimated Market Rate, Percent	4.50%
Maximum [Member] | Private Equity Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Inputs, Earnings before Interest, Taxes, Depreciation, and Amortization Multiple	6
Maximum [Member] | Mortgage Loan Commitments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Probability of Funding	100.00%
Embedded Servicing Value, Mortgage Loan Commitments, Discounted Cash Flow	2.00%
Weighted Average [Member] | Mortgage Loan Commitments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Weighted Average, Probability of Funding	76.00%
Weighted Average, Embedded Servicing Value	1.10%

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Fair Value Disclosures Measured On Nonrecurring Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent impaired loans, fair value	$ 1,236	$ 1,331
Collateral dependent impaired loans, Total Gains (Losses)	(617)	(1,700)
Mortgage servicing rights, fair value	4,653	2,868
Mortgage servicing rights, Total Gains (Losses)	13	7
Foreclosed assets, fair value	0	18
Foreclosed assets, Total Gains (Losses)	(9)	(20)
Long Lived Assets Nonrecurring Basis, fair value	3,378	2,408
Long Lived Assets Nonrecurring Basis Gains (Losses)	(724)	(1,054)
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent impaired loans, fair value	0	0
Mortgage servicing rights, fair value	0	0
Foreclosed assets, fair value	0	0
Long Lived Assets Nonrecurring Basis, fair value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent impaired loans, fair value	0	0
Mortgage servicing rights, fair value	0	0
Foreclosed assets, fair value	0	0
Long Lived Assets Nonrecurring Basis, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent impaired loans, fair value	1,236	1,331
Mortgage servicing rights, fair value	4,653	2,868
Foreclosed assets, fair value	0	18
Long Lived Assets Nonrecurring Basis, fair value	$ 3,378	$ 2,408

Fair Value Of Financial Inst120

Fair Value Of Financial Instruments (Schedule Of Estimated Fair Value Of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 15,300
Available for sale securities	8,774,280	$ 9,649,203
Trading securities	18,269	22,225
Non-marketable	100,758	99,558
Securities Purchased under Agreements to Resell	700,000	725,000
Cash and due from banks	438,439	494,690
Derivative Assets	8,349	13,566
Deferred Compensation Plan Assets	12,843	10,261
Non-interest bearing deposits	7,158,962	7,429,398
Savings, interest checking and money market deposits	11,499,620	11,430,789
Time open and certificates of deposit	1,766,864
Derivative Liability	8,074	13,339
Deferred Compensation Liability, Current and Noncurrent	12,843	10,261
Fair Value Hierarchy, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Derivative Assets	0	0
Deferred Compensation Plan Assets	12,843	10,261
Derivative Liability	0	0
Deferred Compensation Liability, Current and Noncurrent	12,843	10,261
Fair Value Hierarchy, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	18,269	22,225
Derivative Assets	7,723	13,146
Deferred Compensation Plan Assets	0	0
Derivative Liability	7,951	13,177
Deferred Compensation Liability, Current and Noncurrent	0	0
Fair Value Hierarchy, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Derivative Assets	626	420
Deferred Compensation Plan Assets	0	0
Derivative Liability	123	162
Deferred Compensation Liability, Current and Noncurrent	0	0
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	937,011	945,871
Federal funds sold	42,775	15,470
Interest earning deposits with banks	30,631	272,275
Cash and due from banks	438,439	494,690
Deferred Compensation Plan Assets	12,843	10,261
Non-interest bearing deposits	7,158,962	7,429,398
Savings, interest checking and money market deposits	11,499,620	11,430,789
Federal funds purchased	202,370	52,840
Deferred Compensation Liability, Current and Noncurrent	12,843	10,261
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Held-for-sale, Fair Value Disclosure	21,398	14,456
Available for sale securities	7,820,253	8,686,650
Trading securities	18,269	22,225
Derivative Assets	7,723	13,146
Derivative Liability	7,951	13,177
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	17,016	16,682
Non-marketable	100,758	99,558
Securities Purchased under Agreements to Resell	700,000	725,000
Derivative Assets	626	420
Time open and certificates of deposit	1,766,864	2,240,908
Securities sold under agreements to repurchase	1,304,768	1,671,065
Other borrowings	1,758	102,049
Derivative Liability	123	162
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,958,554	4,776,365
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	968,820	791,236
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,697,452	2,643,374
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,062,787	2,010,397
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,104,487	1,990,801
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	400,587	413,634
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Consumer Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	783,864	776,465
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	7,123	10,464
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	937,011	945,871
Federal funds sold	42,775	15,470
Interest earning deposits with banks	30,631	272,275
Cash and due from banks	438,439	494,690
Deferred Compensation Plan Assets	12,843	10,261
Non-interest bearing deposits	7,158,962	7,429,398
Savings, interest checking and money market deposits	11,499,620	11,430,789
Federal funds purchased	202,370	52,840
Deferred Compensation Liability, Current and Noncurrent	12,843	10,261
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Held-for-sale, Fair Value Disclosure	21,398	14,456
Available for sale securities	7,820,253	8,686,650
Trading securities	18,269	22,225
Derivative Assets	7,723	13,146
Derivative Liability	7,951	13,177
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	17,016	16,682
Non-marketable	100,758	99,558
Securities Purchased under Agreements to Resell	695,194	728,179
Derivative Assets	626	420
Time open and certificates of deposit	1,768,780	2,235,218
Securities sold under agreements to repurchase	1,305,375	1,671,227
Other borrowings	1,758	104,298
Derivative Liability	123	162
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,971,401	4,787,469
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	979,389	800,426
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,702,598	2,658,093
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,060,443	2,005,227
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,074,129	1,974,784
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	400,333	414,499
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Consumer Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	798,093	794,856
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value Hierarchy, Level 3 [Member] | Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 7,123	$ 10,464

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Details) $ in Millions	Dec. 31, 2017USD ($)
Derivative [Line Items]
Variation Margin Impact to Positive Fair Values of Cleared Swaps	$ 4.5
Variation Margin Impact to Negative Fair Values of Cleared Swaps	$ 4.3

Derivative Instruments (Schedul

Derivative Instruments (Schedule Of Notional Amounts Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional Amount of Derivatives	$ 1,963,178	$ 1,904,093
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,741,412	1,685,099
Interest Rate Caps [Member]
Derivative [Line Items]
Notional Amount of Derivatives	31,776	59,379
Credit Risk Participation Agreements [Member]
Derivative [Line Items]
Notional Amount of Derivatives	133,488	121,514
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	11,826	4,046
Mortgage Loan Commitments [Member]
Derivative [Line Items]
Notional Amount of Derivatives	17,110	12,429
Mortgage Loan Forward Sale Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,566	6,626
Forward TBA Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	$ 25,000	$ 15,000

Derivative Instruments (Sche123

Derivative Instruments (Schedule Of Fair Values Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Other assets	$ 8,349	$ 13,566
Other liabilities	(8,074)	(13,339)
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Other assets	7,674	12,987
Other liabilities	(7,857)	(12,987)
Interest Rate Caps [Member]
Derivatives, Fair Value [Line Items]
Other assets	16	78
Other liabilities	(16)	(78)
Credit Risk Participation Agreements [Member]
Derivatives, Fair Value [Line Items]
Other assets	46	65
Other liabilities	(123)	(156)
Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Other assets	21	66
Other liabilities	(40)	(4)
Mortgage Loan Commitments [Member]
Derivatives, Fair Value [Line Items]
Other assets	580	355
Other liabilities	0	(6)
Mortgage Loan Forward Sale Contracts [Member]
Derivatives, Fair Value [Line Items]
Other assets	8	0
Other liabilities	(7)	(63)
Forward TBA Contracts [Member]
Derivatives, Fair Value [Line Items]
Other assets	4	15
Other liabilities	$ (31)	$ (45)

Derivative Instruments (Summary

Derivative Instruments (Summary Of The Effects Of Derivative Instruments On Consolidated Statements Of Income) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 1,580	$ 6,041	$ 4,996
Other Non-Interest Income [Member] | Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	1,978	5,927	4,309
Other Non-Interest Income [Member] | Interest Rate Caps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	32
Other Non-Interest Income [Member] | Credit Risk Participation Agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	35	(44)	57
Other Non-Interest Income [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(80)	55	253
Loans Fees And Sales [Member] | Mortgage Loan Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	231	87	263
Loans Fees And Sales [Member] | Mortgage Loan Forward Sale Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	64	(63)	0
Loans Fees And Sales [Member] | Forward TBA Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (648)	$ 79	$ 82

Derivative Instruments Derivati

Derivative Instruments Derivative Instruments (Balance Sheet Offsetting) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Offsetting [Line Items]
Derivative Assets	$ 8,349	$ 13,566
Derivative Asset, Amount Offset by Liabiilty	0	0
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	8,349	13,566
Derivative Liability	8,074	13,339
Derivative Liability, Amount Offset by Asset	0	0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	8,074	13,339
Derivative Subject to Master Netting Agreement [Member]
Balance Sheet Offsetting [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,726	13,111
Derivative Asset, Amount Offset by Liabiilty	0	0
Derivative Asset, Noncurrent	7,726	13,111
Derivative Asset, Not Offset, Policy Election Deduction	(233)	(3,391)
Derivative Asset, Fair Value of Collateral	(824)	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	6,669	9,720
Derivative Liability, Fair Value, Gross Liability	7,935	13,124
Derivative Liability, Amount Offset by Asset	0	0
Derivative Liability, Noncurrent	7,935	13,124
Derivative Liability, Not Offset, Policy Election Deduction	(233)	(3,391)
Derivative Liability, Fair Value of Collateral	(1,570)	(5,292)
Derivative Liability, Fair Value, Amount Offset Against Collateral	6,132	4,441
Derivative Not Subject to Master Netting Agreement [Member]
Balance Sheet Offsetting [Line Items]
Derivative Asset, Fair Value, Gross Asset	623	455
Derivative Asset, Amount Offset by Liabiilty	0	0
Derivative Asset, Not Subject to Master Netting Arrangement	623	455
Derivative Liability, Fair Value, Gross Liability	139	215
Derivative Liability, Amount Offset by Asset	0	0
Derivative Liability, Not Subject to Master Netting Arrangement	$ 139	$ 215

Resale and Repurchase Agreem126

Resale and Repurchase Agreements (Details) - Collateral Swap [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Collateral swap agreements	$ 650	$ 550
Collateral Already Posted, Aggregate Fair Value	661.4
Collateral Accepted, Aggregate Fair Value	$ 661.3

Resale and Repurchase Agreem127

Resale and Repurchase Agreements Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Resale agreement [Member]
Balance Sheet Offsetting [Line Items]
Securities Purchased under Agreements to Resell, Gross	$ 1,350,000	$ 1,275,000
Securities Purchased under Agreements to Resell, Liability	(650,000)	(550,000)
Securities purchased under agreements to resell, net	700,000	725,000
Securities Purchased under Agreements to Resell, Not Subject to Master Netting Arrangement	0	0
Securities Purchased under Agreements to Resell, Collateral, Obligation to Return Securities	(700,000)	(725,000)
Securities Purchased under Agreements to Resell, Amount Offset Against Collateral	0	0
Repurchase agreement [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	1,954,768	2,221,065
Securities Sold under Agreements to Repurchase, Asset	(650,000)	(550,000)
Securities sold under agreements to repurchase, net	1,304,768	1,671,065
Securities Sold under Agreements to Repurchase, Not Subject to Master Netting Arrangement	0	0
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(1,304,768)	(1,671,065)
Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral	$ 0	$ 0

Resale and Repurchase Agreem128

Resale and Repurchase Agreements Schedule of Underlying Assets of Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Maturity Overnight [Member] | US Treasury and Government [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	$ 271,820	$ 294,600
Maturity Overnight [Member] | US Government-sponsored Enterprise Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	149,111	147,694
Maturity Overnight [Member] | Agency mortgage-backed securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	737,975	693,851
Maturity Overnight [Member] | Asset-backed Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	89,601	474,830
Maturity Overnight [Member] | Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	14,780	0
Maturity Overnight [Member] | Repurchase Agreements [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	1,263,287	1,610,975
Maturity up to 90 days [Member] | US Treasury and Government [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	1,731	0
Maturity up to 90 days [Member] | US Government-sponsored Enterprise Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	0	0
Maturity up to 90 days [Member] | Agency mortgage-backed securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	9,750	24,380
Maturity up to 90 days [Member] | Asset-backed Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	30,000	30,000
Maturity up to 90 days [Member] | Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	0	0
Maturity up to 90 days [Member] | Repurchase Agreements [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	41,481	54,380
Maturity Greater than 90 Days [Member] | US Treasury and Government [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	450,000	300,000
Maturity Greater than 90 Days [Member] | US Government-sponsored Enterprise Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	0	3,237
Maturity Greater than 90 Days [Member] | Agency mortgage-backed securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	200,000	252,473
Maturity Greater than 90 Days [Member] | Asset-backed Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	0	0
Maturity Greater than 90 Days [Member] | Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	0	0
Maturity Greater than 90 Days [Member] | Repurchase Agreements [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	650,000	555,710
Total Repurchase Agreements [Member] [Domain] | US Treasury and Government [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	723,551	594,600
Total Repurchase Agreements [Member] [Domain] | US Government-sponsored Enterprise Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	149,111	150,931
Total Repurchase Agreements [Member] [Domain] | Agency mortgage-backed securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	947,725	970,704
Total Repurchase Agreements [Member] [Domain] | Asset-backed Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	119,601	504,830
Total Repurchase Agreements [Member] [Domain] | Debt Securities [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	14,780	0
Total Repurchase Agreements [Member] [Domain] | Repurchase Agreements [Member]
Schedule of Underlying Assets of Repurchase Agreements [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	$ 1,954,768	$ 2,221,065

Commitments, Contingencies A129

Commitments, Contingencies And Guarantees (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating leases, rent expense	$ 7,300	$ 7,100	$ 6,800
Outstanding purchase commitments expected to fund in the next 12 months	114,900
Notional amount of underlying swaps	1,963,178	1,904,093
Financial Standby Letter of Credit [Member]
Carrying value of the guarantee obligations, liability	2,500
Commitments outstanding	387,811	$ 391,899
State Tax Credits [Member]
Purchases of state tax credits	70,900
Sales of state tax credits	47,100
Risk Participation Agreement [Member]
Carrying value of the guarantee obligations, liability	123
Notional amount of underlying swaps	$ 84,100
Risk Participation Agreement [Member] | Minimum [Member]
Risk Participation Agreements, Term	2 years
Risk Participation Agreement [Member] | Maximum [Member]
Risk Participation Agreements, Term	11 years

Commitments, Contingencies A130

Commitments, Contingencies And Guarantees (Summary Of Minimum Lease Commitments) (Details) $ in Thousands	Dec. 31, 2017USD ($)
2,018	$ 6,196
2,019	4,951
2,020	3,893
2,021	3,176
2,022	2,678
After	13,383
Total minimum lease payments	34,277
Real Property [Member]
2,018	5,981
2,019	4,876
2,020	3,861
2,021	3,162
2,022	2,678
After	13,383
Equipment [Member]
2,018	215
2,019	75
2,020	32
2,021	14
2,022	0
After	$ 0

Commitments, Contingencies A131

Commitments, Contingencies And Guarantees (Schedule Of Off-Balance Sheet Instruments Commitments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Commercial letters of credit	$ 4,498	$ 2,962
Credit Card [Member]
Commitments to extend credit	5,102,556	4,932,955
Other [Member]
Commitments to extend credit	5,737,181	5,508,686
Financial Standby Letter of Credit [Member]
Standby letters of credit, net of participations	$ 387,811	$ 391,899

Related Parties (Narrative) (De

Related Parties (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017USD ($)$ / Square_FootRateshares	Dec. 31, 2016USD ($)$ / Square_Foot	Dec. 31, 2015USD ($)$ / Square_Foot
Tower Property [Member]
Percentage of Tower stock owned by the Company's Executive Officers | Rate	66.00%
Company stock owned by Tower | shares	270,646
Tower's long-term line of credit with the Bank	$ 13,500,000
Tower's maximum amount outstanding on the line of credit during period	11,500,000	$ 0	$ 1,300,000
Tower's line of credit, amount borrowed and repaid during the year	5,200,000
Tower's line of credit, current balance	0	0	0
Tower's letters of credit outstanding, amount	0	0	0
Tower's line of credit facility, commitment fee amount	0	0	0
Tower's long-term construction loan	0	0	0
Rent paid to the Company by Tower	$ 74,000	$ 72,000	$ 69,000
Rent per square foot | $ / Square_Foot	15.75	15.67	15.42
Chief Executive Officer [Member]
State tax credits sold by the Company to related party	$ 694,000	$ 549,000	$ 478,000
Former Chief Executive Officer [Member]
State tax credits sold by the Company to related party	0	191,000	40,000
Vice Chairman [Member]
State tax credits sold by the Company to related party	598,000	244,000	372,000
President [Member]
State tax credits sold by the Company to related party	$ 67,000	$ 72,000	$ 65,000

Related Parties (Schedule Of Re

Related Parties (Schedule Of Related Party Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total	$ 2,446	$ 2,485	$ 2,523
Leasing Agent Fees [Member]
Total	32	101	66
Operation Of Parking Garages [Member]
Total	82	184	75
Building Management Fees [Member]
Total	1,954	1,832	1,850
Property Construction Management Fees [Member]
Total	146	147	322
Dividends Paid On Company Stock Held By Tower [Member]
Total	$ 232	$ 221	$ 210

Parent Company Condensed Fin134

Parent Company Condensed Financial Statements (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments in marketable common and preferred stock	$ 48,838,000	$ 51,263,000
Non-agency mortgage-backed securities	905,793,000	1,055,639,000
Donation of securities	32,036,000	0	$ 0
Commerce Bancshares, Inc. (Parent) [Member]
Note receivable due from bank subsidiary	50,000,000	0
Parent's line of credit facility with the Bank, maximum borrowing capacity	20,000,000
Parent line of credit with Bank, borrowings during period	0	$ 0	$ 0
Investments in marketable common and preferred stock	48,700,000
Non-agency mortgage-backed securities	4,600,000
Unrealized net gain in fair value Investment	44,500,000
Net of tax unrealized gain included in stockholders' equity	27,600,000
Unrealized net of tax gain in fair value of investment securities held by subsidiaries	6,200,000
Gain on donation of appreciated securities	31,100,000
Donation of securities	32,000,000
Gain (Loss) on Sale of Investments	10,000,000
Available for sale securities expected to be redeemed next year	$ 45,900,000

Parent Company Condensed Fin135

Parent Company Condensed Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available for sale securities	$ 8,774,280	$ 9,649,203
Non-marketable securities	100,758	99,558
Other assets	401,074	608,408
Total assets	24,833,415	25,641,424
Other liabilities	180,889	213,243
Total liabilities	22,115,231	23,140,292
Stockholders’ equity	2,716,560	2,495,783
Total liabilities and equity	24,833,415	25,641,424
Commerce Bancshares, Inc. (Parent) [Member]
Investment in consolidated subsidiary, Banks	2,409,098	2,246,060
Investment in consolidated subsidiaries, Non-banks	52,479	51,816
Cash	151,607	51
Securities purchased under agreements to resell	0	155,775
Available for sale securities	53,285	58,051
Non-marketable securities	655	718
Note receivable due from bank subsidiary	50,000	0
Advances to subsidiaries, net of borrowings	14,571	5,053
Income tax benefits	8,279	524
Other assets	19,951	17,716
Total assets	2,759,925	2,535,764
Pension obligation	12,407	17,158
Other liabilities	30,958	22,823
Total liabilities	43,365	39,981
Stockholders’ equity	2,716,560	2,495,783
Total liabilities and equity	$ 2,759,925	$ 2,535,764

Parent Company Condensed Fin136

Parent Company Condensed Financial Statements (Condensed Statements Of Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividends on investment securities	$ 214,689	$ 207,184	$ 191,801
Salaries and employee benefits	448,321	427,310	400,701
Data processing fees paid to affiliates	92,246	92,722	83,944
Community Service	34,377	3,906	3,180
Other	77,459	74,202	73,565
Total non-interest expense	769,684	717,065	676,487
Income tax expense (benefit)	110,506	124,151	116,590
NET INCOME ATTRIBUTABLE TO COMMERCE BANCSHARES, INC.	319,383	275,391	263,730
Commerce Bancshares, Inc. (Parent) [Member]
Dividends received from consolidated subsidiary banks	160,002	160,002	160,001
Earnings of consolidated subsidiaries, net of dividends	147,678	118,704	106,636
Interest and dividends on investment securities	2,099	2,364	2,272
Management fees charged subsidiaries	30,431	30,965	25,713
Investment securities gains (losses)	41,717	1,880	0
Net interest income on advances and note to subsidiaries	514	21	4
Other	3,346	2,720	1,422
Total income	385,787	316,656	296,048
Salaries and employee benefits	33,714	29,116	22,167
Professional fees	2,036	1,951	1,833
Data processing fees paid to affiliates	3,512	3,226	3,186
Community Service	32,093	1,620	991
Other	10,671	9,849	8,278
Total non-interest expense	82,026	45,762	36,455
Income tax expense (benefit)	(15,622)	(4,497)	(4,137)
NET INCOME ATTRIBUTABLE TO COMMERCE BANCSHARES, INC.	$ 319,383	$ 275,391	$ 263,730

Parent Company Condensed Fin137

Parent Company Condensed Financial Statements (Condensed Statements Of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES:
Net income	$ 319,900	$ 276,854	$ 266,975
Other changes, net	(6,560)	(26,666)	(3,757)
Net cash provided by (used in) operating activities	433,226	435,757	291,195
INVESTING ACTIVITIES
Proceeds from sales of available for sale securities	792,380	24,380	689,031
Proceeds from maturities/pay downs of available for sale securities	1,899,640	2,032,397	2,515,113
Purchases of investment securities	(1,853,817)	(1,988,101)	(3,542,537)
Purchases of land, buildings and equipment	(30,824)	(24,478)	(31,897)
Net cash provided by (used in) investing activities	220,720	(805,213)	(1,195,402)
FINANCING ACTIVITIES
Purchases of treasury stock	(17,771)	(39,381)	(23,176)
Issuance of stock under equity compensation plans	8	6
Proceeds from stock options exercised			1,914
Cash dividends paid on common stock	(91,619)	(87,070)	(84,961)
Cash dividends paid on preferred stock	(9,000)	(9,000)	(9,000)
Net cash provided by (used in) financing activities	(924,536)	649,172	306,209
Increase (decrease) in cash and cash equivalents	(270,590)	279,716	(597,998)
Cash and cash equivalents at beginning of year	782,435	502,719	1,100,717
Cash and cash equivalents at end of year	511,845	782,435	502,719
Income tax payments (receipts), net	120,744	119,596	95,341
Commerce Bancshares, Inc. (Parent) [Member]
OPERATING ACTIVITIES:
Net income	319,383	275,391	263,730
Earnings of consolidated subsidiaries, net of dividends	(147,678)	(118,704)	(106,636)
Other changes, net	(11,268)	9,541	(1,152)
Net cash provided by (used in) operating activities	160,437	166,228	155,942
INVESTING ACTIVITIES
(Increase) decrease in securities purchased under agreements to resell	155,775	(51,335)	57,210
(Increase) decrease in investment in subsidiaries, net	11	4	(6)
Proceeds from sales of available for sale securities	11,006	2,949	0
Proceeds from maturities/pay downs of available for sale securities	2,295	4,105	3,516
Purchases of investment securities	0	0	2,500
Origination of Notes Receivable from Related Parties	(50,000)	0	0
(Increase) decrease in advances to subsidiaries, net	(9,518)	13,507	1,171
Purchases of land, buildings and equipment	(52)	(3)	(113)
Net cash provided by (used in) investing activities	109,517	(30,773)	59,278
FINANCING ACTIVITIES
Purchases of treasury stock	(17,771)	(39,381)	(23,176)
Accelerated stock repurchase agreement	0	0	(100,000)
Issuance of stock under equity compensation plans	(8)	(6)
Proceeds from stock options exercised			1,914
Cash dividends paid on common stock	(91,619)	(87,070)	(84,961)
Cash dividends paid on preferred stock	(9,000)	(9,000)	(9,000)
Net cash provided by (used in) financing activities	(118,398)	(135,457)	(215,223)
Increase (decrease) in cash and cash equivalents	151,556	(2)	(3)
Cash and cash equivalents at beginning of year	51	53	56
Cash and cash equivalents at end of year	151,607	51	53
Income tax payments (receipts), net	$ (8,991)	$ (8,958)	$ 1,278