First Citizens BancShares (FCNCO) 10-Q 3 May 18 2018 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 03, 2018
Entity Registrant Name	FIRST CITIZENS BANCSHARES INC /DE/
Entity Central Index Key	798,941
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Class A Common Stock
Entity Common Stock, Shares Outstanding		11,005,220
Class B Common Stock
Entity Common Stock, Shares Outstanding		1,005,185

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 248,139	$ 336,150
Overnight investments	1,946,882	1,387,927
Marketable equity securities	110,107	0
Investment securities available for sale	6,857,740	7,180,180
Investment securities held to maturity	74	76
Loans held for sale	46,660	51,179
Loans and Leases	23,611,977	23,596,825
Less allowance for loan and lease losses	(223,116)	(221,893)
Net loans and leases	23,388,861	23,374,932
Premises and equipment	1,140,820	1,138,431
Other real estate	48,089	51,097
Income earned not collected	96,607	95,249
FDIC shared-loss receivable	3,636	2,223
Goodwill	150,601	150,601
Other intangible assets	68,668	73,096
Other assets	329,553	686,371
Total assets	34,436,437	34,527,512
Liabilities
Noninterest-bearing deposits	12,000,741	11,237,375
Interest-bearing deposits	17,968,504	18,028,900
Total deposits	29,969,245	29,266,275
Short-term borrowings	554,758	693,807
Long-term obligations	194,413	870,240
FDIC shared-loss payable	102,466	101,342
Other liabilities	243,441	261,784
Total liabilities	31,064,323	31,193,448
Shareholders' Equity
Surplus	658,918	658,918
Retained earnings	2,931,509	2,785,430
Accumulated other comprehensive loss	(230,323)	(122,294)
Total shareholders' equity	3,372,114	3,334,064
Total liabilities and shareholders' equity	34,436,437	34,527,512
Class A Common Stock
Shareholders' Equity
Common stock	11,005	11,005
Class B Common Stock
Shareholders' Equity
Common stock	$ 1,005	$ 1,005

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Class A Common Stock
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shared authorized	16,000,000	16,000,000
Common stock, shares issued	11,005,220	11,005,220
Common stock, shares outstanding	11,005,220	11,005,220
Class B Common Stock
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shared authorized	2,000,000	2,000,000
Common stock, shares issued	1,005,185	1,005,185
Common stock, shares outstanding	1,005,185	1,005,185
Loans Held For Sale
Fair value of originated loans held for sale	$ 46,660	$ 51,179

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income
Loans and leases	$ 251,982	$ 226,630
Investment securities:
Total investment securities interest and dividend income	35,020	29,751
Overnight investments	5,599	4,476
Total interest income	292,601	260,857
Interest expense
Deposits	3,756	4,436
Short-term borrowings	1,434	580
Long-term obligations	2,974	5,498
Total interest expense	8,164	10,514
Net interest income	284,437	250,343
Provision (credit) for loan and lease losses	7,605	8,231
Net interest income after provision for loan and lease losses	276,832	242,112
Noninterest income
Gain on acquisitions	0	12,017
Cardholder services	14,782	11,907
Merchant services	6,177	6,693
Service charges on deposit accounts	26,543	22,142
Wealth management services	23,569	20,962
Securities gains (losses), net	0	(24)
Marketable equity securities gain (loss), net	971	0
Other service charges and fees	7,480	7,601
Mortgage income	4,237	7,576
Insurance commissions	3,776	3,558
ATM income	2,171	1,773
Adjustments for FDIC shared-loss receivable	(1,478)	(1,628)
Net Impact from FDIC shared-loss termination	0	(45)
Gain (Loss) on Extinguishment of Debt	25,814	0
Other	8,642	7,115
Total noninterest income	122,684	99,647
Noninterest expense
Salaries and wages	129,203	116,362
Employee benefits	32,091	27,178
Occupancy expense	27,954	24,762
Equipment expense	24,974	24,588
Merchant processing		18,300
Cardholder processing		6,800
FDIC insurance expense	5,733	5,593
Foreclosure-related expenses	4,146	3,763
Merger-related expenses	598	833
Other	43,364	33,621
Total noninterest expense	268,063	236,700
Income before income taxes	131,453	105,059
Income taxes	31,222	37,438
Net income	$ 100,231	$ 67,621
Average shares outstanding (in shares)	12,010,405	12,010,405
Net income per share	$ 8.35	$ 5.63

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 100,231	$ 67,621
Unrealized gains and losses on securities:
Change in unrealized securities gains (losses) arising during period	(78,634)	36,096
Tax effect	18,088	(13,419)
Reclassification adjustment for net gains realized and included in income before income taxes	0	24
Tax effect	0	(9)
Total change in unrealized gains and losses on securities, net of tax	(60,546)	22,692
Change in fair value of cash flow hedges:
Change in unrecognized loss on cash flow hedges	0	0
Tax effect	0	0
Total change in unrecognized loss on cash flow hedges, net of tax	0	0
Change in pension obligation:
Amortization of actuarial losses and prior service cost	3,337	2,500
Tax effect	(768)	(941)
Total change in pension obligation, net of tax	2,569	1,559
Net current period other comprehensive income	(57,977)	24,251
Total comprehensive income	$ 42,254	$ 91,872

Consolidated Statements of Chan

Consolidated Statements of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Common StockClass A Common Stock	Common StockClass B Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Loss	Financial Instruments ASU cumulative effect adjustment	Financial Instruments ASU cumulative effect adjustmentRetained Earnings	Financial Instruments ASU cumulative effect adjustmentAccumulated Other Comprehensive Loss	Income tax ASU cumulative effect adjustment	Income tax ASU cumulative effect adjustmentRetained Earnings	Income tax ASU cumulative effect adjustmentAccumulated Other Comprehensive Loss
Shareholders' equity	$ 3,012,427	$ 11,005	$ 1,005	$ 658,918	$ 2,476,691	$ (135,192)
Net income	67,621	0	0	0	67,621	0
Other comprehensive income, net of tax	24,251	0	0	0	0	24,251
Cash dividends	(3,603)	0	0	0	(3,603)	0
Shareholders' equity	3,100,696	11,005	1,005	658,918	2,540,709	(110,941)
Shareholders' equity	3,334,064	11,005	1,005	658,918	2,785,430	(122,294)
Net income	100,231	0	0	0	100,231	0
Other comprehensive income, net of tax	(57,977)	0	0	0	0	(57,977)
Cash dividends	(4,204)	0	0	0	(4,204)	0
Cumulative Effect of New Accounting Principle in Period of Adoption							$ 18,700	$ 18,700	$ (18,700)	$ 31,300	$ 31,300	$ (31,300)
Shareholders' equity	$ 3,372,114	$ 11,005	$ 1,005	$ 658,918	$ 2,931,509	$ (230,323)

Consolidated Statements of Cha7

Consolidated Statements of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.35	$ 0.30

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES
Net income	$ 100,231	$ 67,621
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	7,605	8,231
Deferred tax expense (benefit)	(5,573)	6,693
Net change in current taxes	33,128	27,462
Depreciation	23,179	22,616
Net increase (decrease) in accrued interest payable	(2,454)	150
Net (increase) decrease in income earned not collected	(1,358)	(617)
Gain on acquisitions	0	(12,017)
Securities (gains) losses, net	0	24
Marketable equity securities gain (loss), net	(971)	0
Gain on extinguishment of debt	(25,814)	0
Loss on termination of FDIC shared-loss agreements	0	45
Origination of loans held for sale	(131,353)	(134,932)
Proceeds from sale of loans held for sale	138,538	162,837
Gain on sale of loans held for sale	(2,666)	(3,456)
(Gain) loss on sale of portfolio loans	0	(164)
Net writedowns/losses on other real estate	1,210	1,717
(Gain) loss on sales of premises and equipment	0	(156)
Net accretion of premiums and discounts	(10,323)	(10,985)
Amortization of intangible assets	6,049	5,271
Reduction FDIC receivable for shared-loss agreements	(1,834)	2,591
Net increase (decrease) in FDIC payable for shared-loss agreements	1,124	1,005
Net change in other assets	342,312	(15,078)
Net change in other liabilities	(12,642)	8,741
Net cash provided by operating activities	458,388	137,599
INVESTING ACTIVITIES
Net change in loans outstanding	(7,283)	(105,100)
Purchases of investment securities available for sale	(374,850)	(871,698)
Payments to Acquire Marketable Securities	(2,272)	0
Proceeds from maturities of investment securities held to maturity	2	15
Proceeds from maturities of investment securities available for sale	503,717	787,182
Proceeds from sales of investment securities available for sale	0	14,162
Proceeds from Sale and Maturity of Marketable Securities	664	0
Net change in overnight investments	(558,955)	(856,442)
Proceeds from sales of portfolio loans	0	32,294
Cash (paid to) received from the FDIC for shared-loss agreements	0	(2,760)
Net payment to the FDIC for termination of shared-loss agreements	0	(285)
Proceeds from sale of other real estate	8,380	8,845
Proceeds fro sales of premises and equipment	13	2,205
Additions to premises and equipment	(24,081)	(15,459)
Net cash acquired in business acquisitions	0	25,646
Net cash (used) provided by investing activities	(454,665)	(981,395)
FINANCING ACTIVITIES
Net change in time deposits	(92,064)	(107,339)
Net change in demand and other interest-bearing deposits	795,034	827,009
Net change in short-term borrowings	(139,049)	87,100
Repayment of long-term obligations	(651,451)	(442)
Cash dividends paid	(4,204)	0
Net cash provided (used) by financing activities	(91,734)	806,328
Change in cash and due from banks	(88,011)	(37,468)
Cash and due from banks at beginning of period	336,150	539,741
Cash and due from banks at end of period	248,139	502,273
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	6,582	5,822
Dividends declared but not paid	4,204	3,603
Transfer of Portfolio Loans and Leases to Held-for-sale	$ 0	$ 32,130

Accounting Policies and Basis o

Accounting Policies and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Accounting Policies and Basis of Presentation	ACCOUNTING POLICIES AND BASIS OF PRESENTATION First Citizens BancShares, Inc. (BancShares) is a financial holding company organized under the laws of Delaware and conducts operations through its banking subsidiary, First-Citizens Bank & Trust Company (FCB), which is headquartered in Raleigh, North Carolina. General These consolidated financial statements and notes thereto are presented in accordance with instructions for Form 10-Q and Article 10 of Regulation S-X and, therefore, do not include all information and notes necessary for a complete presentation of financial position, results of operations and cash flow activity required in accordance with accounting principles generally accepted in the United States of America (GAAP). In the opinion of management, all normal recurring adjustments necessary for a fair presentation of the consolidated financial position and consolidated results of operations have been made. The unaudited interim consolidated financial statements included in this Form 10-Q should be read in conjunction with the consolidated financial statements and notes to consolidated financial statements included in BancShares' Annual Report on Form 10-K for the year ended December 31, 2017 . Reclassifications In certain instances, amounts reported in prior years' consolidated financial statements have been reclassified to conform to the current financial statement presentation. Such reclassifications had no effect on previously reported cash flows, shareholders' equity or net income. Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported. Actual results could differ from those estimates, and different assumptions in the application of these policies could result in material changes in BancShares' consolidated financial position, the consolidated results of its operations or related disclosures. Material estimates that are particularly susceptible to significant change include: • Allowance for loan and lease losses; • Fair value of financial instruments, including acquired assets and assumed liabilities; • Pension plan assumptions; • Cash flow estimates on purchased credit-impaired loans; • Goodwill and other intangible assets; • Federal Deposit Insurance Corporation (FDIC) shared-loss payable; and • Income tax assets, liabilities and expense Recently Adopted Accounting Pronouncements FASB ASU 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10) The amendments in this ASU provide clarification on certain aspects related to the guidance issued in ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The areas for correction or improvement include (1) equity securities without a readily determinable fair value - discontinuation; (2) equity securities without a readily determinable fair value - adjustments; (3) forward contracts and purchased options; (4) presentation requirements for certain fair value option liabilities; (5) fair value option liabilities denominated in a foreign currency; and (6) transition guidance for equity securities without a readily determinable fair value. This ASU is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. Early adoption is permitted. We adopted the guidance effective in the first quarter of 2018. The adoption did not have a material impact on our consolidated financial position or consolidated results of operations. FASB ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This ASU requires a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the newly enacted federal corporate income tax rate in the Tax Cuts and Jobs Act of 2017 (Tax Act), which was enacted on December 22, 2017. The Tax Act included a reduction to the corporate income tax rate from 35 percent to 21 percent effective January 1, 2018. The amount of the reclassification would be the difference between the historical corporate income tax rate and the newly enacted 21 percent corporate income tax rate. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We adopted the guidance effective in the first quarter of 2018. The change in accounting principle was accounted for as a cumulative-effect adjustment to the balance sheet resulting in a $31.3 million increase to retained earnings and a corresponding decrease to AOCI on January 1, 2018. FASB ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This ASU requires employers to present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Employers will present the other components separately from the line item that includes the service cost. In addition, only the service cost component of net benefit cost is eligible for capitalization. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted the guidance effective in the first quarter of 2018. The adoption did not have a material impact on our consolidated financial position or consolidated results of operations. FASB ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This ASU addresses the diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The amendments in this ASU provide guidance on (1) debt prepayment or debt extinguishment costs; (2) settlement of zero-coupon debt instruments; (3) contingent consideration payments made after a business combination; (4) proceeds from the settlement of insurance claims; (5) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (6) distributions received from equity method investees; (7) beneficial interests in securitization transactions; and (8) separately identifiable cash flows and application of the predominance principle. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance requires application using a retrospective transition method. We adopted the guidance effective in the first quarter of 2018. The adoption did not have any impact on our Consolidated Statements of Cash Flows. FASB ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10) : Recognition and Measurement of Financial Assets and Financial Liabilities This ASU addresses certain aspects of recognition, measurement, presentation and disclosure of certain financial instruments. The amendments in this ASU (1) require most equity investments to be measured at fair value with changes in fair value recognized in net income; (2) simplify the impairment assessment of equity investments without a readily determinable fair value; (3) eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet; (4) require public business entities to use exit price notion, rather than entry prices, when measuring fair value of financial instruments for disclosure purposes; (5) require separate presentation of financial assets and financial liabilities by measurement category and form of financial assets on the balance sheet or the accompanying notes to the financial statements; (6) require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; and (7) state that a valuation allowance on deferred tax assets related to available-for-sale securities should be evaluated in combination with other deferred tax assets. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted the guidance effective in the first quarter of 2018. The change in accounting principle was accounted for as a cumulative-effect adjustment to the balance sheet resulting in an $18.7 million increase to retained earnings and a decrease to AOCI on January 1, 2018. With the adoption of this ASU equity securities can no longer be classified as available for sale, as such marketable equity securities will be disclosed as a separate line item on the balance sheet with changes in the fair value of equity securities reflected in net income. For equity investments without a readily determinable fair value, BancShares has elected to measure the equity investments using the measurement alternative which requires BancShares to make a qualitative assessment of whether the investment is impaired at each reporting period. Under the measurement alternative these investments will be measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for an identical or similar investment of the same issuer. If a qualitative assessment indicates that the investment is impaired, BancShares will estimate the investment's fair value in accordance with ASC 820 and, if the fair value is less than the investment's carrying value, recognize an impairment loss in net income equal to the difference between carrying value and fair value. Equity investments without a readily determinable fair value are recorded within other assets in the consolidated balance sheets. FASB ASU 2014-09, Revenue from Contracts with Customers (Topic 606) In May 2014, the FASB issued a standard on the recognition of revenue from contracts with customers with the core principle being for a company to recognize revenue to depict the transfer of goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard, which provides a five step model to determine when and how revenue is recognized, also results in enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively and improves guidance for multiple-element arrangements. Per ASU 2015-14, Deferral of the Effective Date , this guidance was deferred and is effective for fiscal periods beginning after December 15, 2017, including interim reporting periods within that reporting period. We adopted the guidance effective in the first quarter of 2018. Our revenue is comprised primarily of net interest income on financial assets and liabilities, which is explicitly excluded from the scope of the new guidance, and noninterest income. The contracts that are in scope of the guidance are primarily related to cardholder and merchant services income, service charges on deposit accounts, wealth management services income, other service charges and fees, insurance commissions, ATM income, sales of other real estate and other. Based on our overall assessment of revenue streams and review of related contracts affected by the ASU, the adoption of this guidance did not change the method in which we currently recognize revenue. We also completed an evaluation of the costs related to these revenue streams to determine whether such costs should be presented as expenses or contra-revenue (i.e., gross vs. net). Based on this evaluation, we determined that the classification of cardholder and merchant processing costs as well as expenses for cardholder reward programs should be netted against cardholder and merchant services income. We used the full retrospective method of adoption and restated the prior financial statements to net the cardholder and merchant processing costs against the related cardholder and merchant services income. These classification changes resulted in changes to both noninterest income and noninterest expense, however, there was no change to previously reported net income. Merchant processing expenses of $18.3 million have been reclassified and reported as a component of merchant services income for the three months ended March 31, 2017. Cardholder processing expenses of $6.8 million and cardholder reward programs expense of $2.5 million have been reclassified and reported as a component of cardholder services income for the three months ended March 31, 2017. Recently Issued Accounting Pronouncements FASB ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This ASU eliminates Step 2 from the goodwill impairment test. Under Step 2, an entity had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities (including unrecognized assets and liabilities) following the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. Instead, under the amendments in this ASU, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This ASU eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative test. This ASU will be effective for BancShares' annual or interim goodwill impairment tests for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We expect to adopt the guidance for our annual impairment test in fiscal year 2020. BancShares does not anticipate any impact to our consolidated financial position or consolidated results of operations as a result of the adoption. FASB ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This ASU eliminates the delayed recognition of the full amount of credit losses until the loss was probable of occurring and instead will reflect an entity's current estimate of all expected credit losses. The amendments in this ASU broaden the information that an entity must consider in developing its expected credit loss estimate for assets measured either collectively or individually. The ASU does not specify a method for measuring expected credit losses and allows an entity to apply methods that reasonably reflect its expectations of the credit loss estimate based on the entity's size, complexity and risk profile. In addition, the disclosures of credit quality indicators in relation to the amortized cost of financing receivables, a current disclosure requirement, are further disaggregated by year of origination. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018. We will adopt the guidance by the first quarter of 2020 with a cumulative-effect adjustment to retained earnings as of the beginning of the year of adoption. For BancShares, the standard will apply to loans, unfunded loan commitments and debt securities. We have formed a cross-functional team co-led by Corporate Finance and Risk Management with executive sponsorship and engaged a third party to assist with the adoption. The implementation team has developed a detailed project plan and is staying informed about the broader industry's perspective and insights, and identifying and researching key decision points. We have completed the readiness assessment and gap analysis related to data, modeling IT, accounting policy, controls and reporting which has enabled us to determine the areas of focus and estimate total body of work. Our current critical activities include model design, accounting policy development, data feasibility analysis, evaluation of reporting and disclosure solutions and completion of specific work stream project plans. We will continue to evaluate the impact the new standard will have on our consolidated financial statements as the final impact will be dependent, among other items, upon the loan portfolio composition and credit quality at the adoption date, as well as economic conditions, financial models used and forecasts at that time. FASB ASU 2016-02, Leases (Topic 842) This ASU increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The key difference between existing standards and this ASU is the requirement for lessees to recognize all lease contracts on their balance sheet. This ASU requires lessees to classify leases as either operating or finance leases, which are substantially similar to the current operating and capital leases classifications. The distinction between these two classifications under the new standard does not relate to balance sheet treatment, but relates to treatment in the statements of income and cash flows. Lessor guidance remains largely unchanged with the exception of how a lessor determines the appropriate lease classification for each lease to better align the lessor guidance with revised lessee classification guidance. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We will adopt during the first quarter of 2019. We expect an increase to the Consolidated Balance Sheets for right-of-use assets and associated lease liabilities, as well as resulting depreciation expense of the right-of-use assets and interest expense of the lease liabilities in the Consolidated Statements of Income, for arrangements previously accounted for as operating leases. Additionally, adding these assets to our balance sheet will impact our total risk-weighted assets used to determine our regulatory capital levels. Our impact analysis on this change in accounting principle estimates an increase to the Consolidated Balance Sheets for total lease liability ranging between $65.0 million and $85.0 million , as the initial gross up of both assets and liabilities. Capital is expected to be impacted by an estimated four to six basis points. These are preliminary estimates subject to change and will continue to be refined closer to adoption. Revenue Recognition The principles based standard requires disclosure of qualitative and quantitative information surrounding the amount, nature, timing and uncertainty of revenues and cash flows arising from contracts with customers. The core principle of the new standard is that revenue should be recognized when a company transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Descriptions of our noninterest revenue-generating activities that are within the scope of the new revenue ASU is broadly segregated as follows: Cardholder and Merchant Services - These represent interchange fees from customer debit and credit card transactions that are earned at the time a cardholder engages in a transaction with a merchant as well as fees charged to merchants for providing them the ability to accept and process the debit and credit card transaction. Revenue is recognized when the performance obligation has been met as it is satisfied upon the completion of the card transaction. Additionally, ASU 2014-09 requires us to report costs associated with cardholder and merchant services transactions to be netted against the fees from such transactions. Service Charges on Deposit Accounts - These deposit account-related fees represent monthly account maintenance and transaction-based service fees such as overdraft fees, stop payment fees and charges for issuing cashier's checks and money orders. For account maintenance services, revenue is recognized at the end of the statement period when our performance obligation has been satisfied. All other revenues from transaction-based services are recognized at a point in time when the performance obligation has been completed. Wealth Management Services - These primarily represent annuity fees, sales commissions, management fees, insurance sales, and trust and asset management fees. The performance obligation for wealth management services is the provision of services to place annuity products issued by the counterparty to investors, and the provision of services to manage the client’s assets, including brokerage custodial and other management services. Revenue is recognized over the period in which services are performed, are based on a percentage of the value of the assets under management/administration, and are fixed or variable based on account type, or are transaction-based. Other Service Charges and Fees - These include, but are not limited to, check cashing fees, international banking fees, internet banking fees, wire transfer fees and safe deposit fees. These fees are charged, and revenue is recognized, at the point in time the service being requested by the customer is provided thus satisfying our performance obligation. Insurance Commissions - These represent commissions earned on the issuance of insurance products and services. The performance obligation is generally satisfied upon the issuance of the insurance policy and revenue is recognized when the commission payment is remitted by the insurance carrier or policy holder depending on if the billing is performed by FCB or the carrier. ATM Income - These represent fees imposed on customers and non-customers for engaging in an ATM transaction. Revenue is recognized at the time of the transaction as the performance obligation of rendering the ATM service has been met. Sales of Other Real Estate - ORE property consists of foreclosed real estate used as collateral for loans, closed branches, land acquired and no longer intended for future use by FCB, and other real estate purchased for resale as ORE. Revenue is generally recognized on the date of sale where the performance obligation of providing access and transferring control of the specified ORE property to the buyer in good faith and good title is satisfied. This is recorded as a component of other noninterest income. Other - This consists of several forms of recurring revenue such as external rental income, parking income, FHLB dividends, and income earned on changes in the cash surrender value of bank-owned life insurance, all of which are outside the scope of ASU 2014-09. The remaining miscellaneous income is the result of immaterial transactions where revenue is recognized when, or as, the performance obligation is satisfied.

Business Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Business Combinations	NOTE B - BUSINESS COMBINATIONS HomeBancorp, Inc. On May 1, 2018, FCB completed the merger of Tampa, Florida-based HomeBancorp, Inc. (HomeBancorp) and its subsidiary, HomeBanc, into FCB. Under the terms of the merger agreement, cash consideration of $15.03 was paid to the shareholders of HomeBancorp for each share of HomeBancorp's common stock, with total consideration paid of $113.7 million . The merger will allow FCB to expand its footprint in Florida by entering into two new markets in Tampa and Orlando. As of March 31, 2018, HomeBancorp had $912.6 million in consolidated assets, $597.7 million in loans and $647.1 million in deposits. Due to the close proximity of the acquisition date and the date that BancShares' financial statements were issued, preliminary fair value estimates are not available.

Loans and Leases

Loans and Leases	3 Months Ended
	Mar. 31, 2018
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	LOANS AND LEASES BancShares' accounting methods for loans and leases differ depending on whether they are purchased credit-impaired (PCI) or non-PCI. Non-PCI loans and leases include originated commercial and noncommercial, purchased non-impaired loans, purchased leases and certain purchased revolving credit. For purchased non-impaired loans to be included as non-PCI, it must be determined that the loans do not have any credit deterioration at the time of acquisition. Conversely, loans for which it is probable at acquisition that all required payments will not be collected in accordance with contractual terms are considered impaired and, therefore, classified as PCI loans. PCI loans are accounted for under the guidance in ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality . PCI loans are recorded at fair value at the date of acquisition. No allowance for loan and lease losses is recorded on the acquisition date as the fair value of the acquired assets incorporates assumptions regarding credit risk over the life of the loans. An allowance is recorded if there is additional credit deterioration after the acquisition date. BancShares reports PCI and non-PCI loan portfolios separately, and each portfolio is further divided into commercial and non-commercial based on the type of borrower, purpose, collateral, and/or our underlying credit management processes. Additionally, commercial and non-commercial loans are assigned to loan classes, which further disaggregate loans based upon common risk characteristics. Commercial – Commercial loan classes include construction and land development, commercial mortgage, other commercial real estate, commercial and industrial, lease financing and other. Construction and land development – Construction and land development consists of loans to finance land for development, investment, and use in a commercial business enterprise; multifamily apartments; and other commercial buildings that may be owner-occupied or income generating investments for the owner. Commercial mortgage – Commercial mortgage consists of loans to purchase or refinance owner-occupied nonresidential and investment properties. Investment properties include office buildings and other facilities that are rented or leased to unrelated parties. Other commercial real estate – Other commercial real estate consists of loans secured by farmland (including residential farms and other improvements) and multifamily (5 or more) residential properties. Commercial and industrial – Commercial and industrial consists of loans or lines of credit to finance corporate credit cards, accounts receivable, inventory and other general business purposes. Lease financing – Lease financing consists solely of lease financing agreements for business equipment, vehicles and other assets. Other – Other consists of all other commercial loans not classified in one of the preceding classes. These typically include loans to non-profit organizations such as churches, hospitals, educational and charitable organizations, and certain loans repurchased with government guarantees. Noncommercial – Noncommercial loan classes consist of residential and revolving mortgage, construction and land development, and consumer loans. Residential mortgage – Residential real estate consists of loans to purchase, construct or refinance the borrower's primary dwelling, second residence or vacation home. Revolving mortgage – Revolving mortgage consists of home equity lines of credit that are secured by first or second liens on the borrower's primary residence. Construction and land development – Construction and land development consists of loans to construct the borrower's primary or secondary residence or vacant land upon which the owner intends to construct a dwelling at a future date. Consumer – Consumer loans consist of installment loans to finance purchases of vehicles, unsecured home improvements, student loans and revolving lines of credit that can be secured or unsecured, including personal credit cards. Loans and leases outstanding included the following at March 31, 2018 and December 31, 2017 : (Dollars in thousands) March 31, 2018 December 31, 2017 Non-PCI loans and leases: Commercial: Construction and land development $ 738,413 $ 669,215 Commercial mortgage 9,859,136 9,729,022 Other commercial real estate 386,734 473,433 Commercial and industrial 2,695,205 2,730,407 Lease financing 910,589 894,801 Other 281,485 302,176 Total commercial loans 14,871,562 14,799,054 Noncommercial: Residential mortgage 3,587,791 3,523,786 Revolving mortgage 2,651,648 2,701,525 Construction and land development 243,114 248,289 Consumer 1,554,025 1,561,173 Total noncommercial loans 8,036,578 8,034,773 Total non-PCI loans and leases 22,908,140 22,833,827 PCI loans: Commercial: Construction and land development 9,316 10,135 Commercial mortgage 325,073 358,103 Other commercial real estate 16,179 17,124 Commercial and industrial 3,732 6,374 Other 1,628 1,683 Total commercial loans 355,928 393,419 Noncommercial: Residential mortgage 282,338 299,318 Revolving mortgage 60,388 63,908 Construction and land development 3,006 4,163 Consumer 2,177 2,190 Total noncommercial loans 347,909 369,579 Total PCI loans 703,837 762,998 Total loans and leases $ 23,611,977 $ 23,596,825 At March 31, 2018 , $65.5 million of total residential loans and leases were covered under shared-loss agreements with the FDIC, compared to $67.8 million at December 31, 2017 . The shared-loss agreements, for their terms, protect BancShares from a substantial portion of the credit and asset quality risk that would otherwise be incurred. At March 31, 2018 , $9.11 billion in noncovered loans with a lendable collateral value of $6.26 billion were used to secure $85.2 million in Federal Home Loan Bank (FHLB) of Atlanta advances, resulting in additional borrowing capacity of $6.17 billion . At December 31, 2017 , $8.75 billion in noncovered loans with a lendable collateral value of $6.08 billion were used to secure $835.2 million in FHLB of Atlanta advances, resulting in additional borrowing capacity of $5.24 billion . At March 31, 2018 , $2.86 billion in noncovered loans with a lendable collateral value of $2.16 billion were used to secure additional borrowing capacity at the Federal Reserve Bank (FRB). At December 31, 2017 , $2.77 billion in noncovered loans with a lendable collateral value of $2.08 billion were used to secure additional borrowing capacity at the FRB. Certain residential real estate loans are originated to be sold to investors and are recorded in loans held for sale at fair value. Loans held for sale totaled $46.7 million and $51.2 million at March 31, 2018 and December 31, 2017 , respectively. In addition, we may change our strategy for certain portfolio loans and sell them in the secondary market. At that time, portfolio loans are transferred to loans held for sale at the lower of amortized cost or market. During the first quarter of 2018 , total proceeds from sales of loans held for sale were $138.5 million and there were no transfers to loans held for sale from the residential mortgage portfolio. During the first quarter of 2017 , total proceeds from sales of loans held for sale were $195.1 million of which $32.3 million in sales were transferred to loans held for sale from the residential mortgage portfolio, resulting in a gain of $164 thousand . Net deferred fees on originated non-PCI loans and leases, including unearned income as well as unamortized costs and fees, were $1.5 million and $1.7 million at March 31, 2018 and December 31, 2017 , respectively. The unamortized discount related to purchased non-PCI loans and leases in the Guaranty Bank (Guaranty), Cordia Bancorp Inc. (Cordia) and First Citizens Bancorporation, Inc. (Bancorporation) acquisitions was $13.3 million , $2.5 million and $16.4 million , respectively, at March 31, 2018 . At December 31, 2017 , the unamortized discount related to purchased non-PCI loans and leases from the Guaranty, Cordia and Bancorporation acquisitions was $14.2 million , $2.7 million and $18.1 million , respectively. During the three months ended March 31, 2018 and March 31, 2017 , accretion income on purchased non-PCI loans and leases was $2.9 million and $3.2 million , respectively. Credit quality indicators Loans and leases are monitored for credit quality on a recurring basis. The credit quality indicators used are dependent on the portfolio segment to which the loan relates. Commercial and noncommercial loans and leases have different credit quality indicators as a result of the unique characteristics of the loan segment being evaluated. The credit quality indicators for non-PCI and PCI commercial loans and leases are developed through a review of individual borrowers on an ongoing basis. Commercial loans are evaluated periodically with more frequent evaluations done on more severely criticized loans or leases. The credit quality indicators for non-PCI and PCI noncommercial loans are based on the delinquency status of the borrower. As the borrower becomes more delinquent, the likelihood of loss increases. The indicators represent the rating for loans or leases as of the date presented based on the most recent assessment performed. These credit quality indicators are defined as follows: Pass – A pass rated asset is not adversely classified because it does not display any of the characteristics for adverse classification. Special mention – A special mention asset has potential weaknesses that deserve management’s close attention. If left uncorrected, such potential weaknesses may result in deterioration of the repayment prospects or collateral position at some future date. Special mention assets are not adversely classified and do not warrant adverse classification. Substandard – A substandard asset is inadequately protected by the current net worth and paying capacity of the borrower or of the collateral pledged, if any. Assets classified as substandard generally have a well-defined weakness, or weaknesses, that jeopardize the liquidation of the debt. These assets are characterized by the distinct possibility of loss if the deficiencies are not corrected. Doubtful – An asset classified as doubtful has all the weaknesses inherent in an asset classified substandard with the added characteristic that the weaknesses make collection or liquidation in full highly questionable and improbable on the basis of currently existing facts, conditions and values. Loss – Assets classified as loss are considered uncollectible and of such little value that it is inappropriate to be carried as an asset. This classification is not necessarily equivalent to any potential for recovery or salvage value, but rather that it is not appropriate to defer a full charge-off even though partial recovery may be affected in the future. Ungraded – Ungraded loans represent loans that are not included in the individual credit grading process due to their relatively small balances or borrower type. The majority of ungraded loans at March 31, 2018 and December 31, 2017 relate to business credit cards. Business credit card loans are subject to automatic charge-off when they become 120 days past due in the same manner as unsecured consumer lines of credit. The remaining balance is comprised of a small amount of commercial mortgage, lease financing and other commercial real estate loans. Non-PCI loans and leases outstanding at March 31, 2018 and December 31, 2017 by credit quality indicator are provided below: March 31, 2018 (Dollars in thousands) Non-PCI commercial loans and leases Grade: Construction and land Commercial Other Commercial and Lease financing Other Total non-PCI commercial loans and leases Pass $ 733,253 $ 9,661,079 $ 382,679 $ 2,476,337 $ 900,464 $ 278,367 $ 14,432,179 Special mention 483 81,680 1,187 37,571 3,347 1,107 125,375 Substandard 4,639 115,039 2,868 19,357 6,734 1,889 150,526 Doubtful — 1,338 — 836 — 72 2,246 Ungraded 38 — — 161,104 44 50 161,236 Total $ 738,413 $ 9,859,136 $ 386,734 $ 2,695,205 $ 910,589 $ 281,485 $ 14,871,562 December 31, 2017 Non-PCI commercial loans and leases Construction and land Commercial Other Commercial and Lease financing Other Total non-PCI commercial loans and leases Pass $ 665,197 $ 9,521,019 $ 468,942 $ 2,511,307 $ 883,779 $ 298,064 $ 14,348,308 Special mention 691 78,643 1,260 44,130 4,340 2,919 131,983 Substandard 3,327 128,848 3,224 18,617 6,585 1,193 161,794 Doubtful — 262 — 385 — — 647 Ungraded — 250 7 155,968 97 — 156,322 Total $ 669,215 $ 9,729,022 $ 473,433 $ 2,730,407 $ 894,801 $ 302,176 $ 14,799,054 March 31, 2018 Non-PCI noncommercial loans and leases (Dollars in thousands) Residential mortgage Revolving mortgage Construction and land development Consumer Total non-PCI noncommercial Current $ 3,542,327 $ 2,628,122 $ 239,107 $ 1,541,749 $ 7,951,305 30-59 days past due 23,833 9,364 2,885 6,935 43,017 60-89 days past due 2,429 3,636 — 2,440 8,505 90 days or greater past due 19,202 10,526 1,122 2,901 33,751 Total $ 3,587,791 $ 2,651,648 $ 243,114 $ 1,554,025 $ 8,036,578 December 31, 2017 Non-PCI noncommercial loans and leases Residential Revolving Construction Consumer Total non-PCI noncommercial Current $ 3,465,935 $ 2,674,390 $ 239,648 $ 1,546,473 $ 7,926,446 30-59 days past due 27,886 13,428 7,154 8,812 57,280 60-89 days past due 8,064 3,485 108 2,893 14,550 90 days or greater past due 21,901 10,222 1,379 2,995 36,497 Total $ 3,523,786 $ 2,701,525 $ 248,289 $ 1,561,173 $ 8,034,773 PCI loans outstanding at March 31, 2018 and December 31, 2017 by credit quality indicator are provided below: March 31, 2018 (Dollars in thousands) PCI commercial loans Grade: Construction and land development Commercial mortgage Other commercial real estate Commercial and industrial Other Total PCI commercial loans Pass $ 3,691 $ 157,187 $ 12,739 $ 1,642 $ 254 $ 175,513 Special mention 338 61,443 307 488 928 63,504 Substandard 4,231 101,734 2,615 1,492 446 110,518 Doubtful 1,056 4,709 518 81 — 6,364 Ungraded — — — 29 — 29 Total $ 9,316 $ 325,073 $ 16,179 $ 3,732 $ 1,628 $ 355,928 December 31, 2017 PCI commercial loans Construction Commercial Other Commercial Other Total PCI commercial Pass $ 1,817 $ 181,353 $ 13,830 $ 4,057 $ 275 $ 201,332 Special mention 320 61,295 323 374 945 63,257 Substandard 5,792 106,807 2,163 1,843 463 117,068 Doubtful 2,206 8,648 808 73 — 11,735 Ungraded — — — 27 — 27 Total $ 10,135 $ 358,103 $ 17,124 $ 6,374 $ 1,683 $ 393,419 March 31, 2018 PCI noncommercial loans (Dollars in thousands) Residential Revolving Construction Consumer Total PCI noncommercial Current $ 249,443 $ 53,885 $ 2,420 $ 2,095 $ 307,843 30-59 days past due 9,196 1,662 19 40 10,917 60-89 days past due 1,436 851 — — 2,287 90 days or greater past due 22,263 3,990 567 42 26,862 Total $ 282,338 $ 60,388 $ 3,006 $ 2,177 $ 347,909 December 31, 2017 PCI noncommercial loans Residential Revolving Construction Consumer Total PCI noncommercial Current $ 257,166 $ 55,871 $ 3,521 $ 2,074 $ 318,632 30-59 days past due 10,525 2,767 — 51 13,343 60-89 days past due 4,846 701 642 23 6,212 90 days or greater past due 26,781 4,569 — 42 31,392 Total $ 299,318 $ 63,908 $ 4,163 $ 2,190 $ 369,579 The aging of the outstanding non-PCI loans and leases, by class, at March 31, 2018 and December 31, 2017 is provided in the table below. The calculation of days past due begins on the day after payment is due and includes all days through which all required interest or principal has not been paid. Loans and leases 30 days or less past due are considered current as various grace periods allow borrowers to make payments within a stated period after the due date and still remain in compliance with the loan agreement. March 31, 2018 (Dollars in thousands) 30-59 days past due 60-89 days past due 90 days or greater Total past due Current Total loans and leases Non-PCI loans and leases: Construction and land development - commercial $ 2,011 $ 771 $ 357 $ 3,139 $ 735,274 $ 738,413 Commercial mortgage 9,813 4,738 7,058 21,609 9,837,527 9,859,136 Other commercial real estate 94 22 73 189 386,545 386,734 Commercial and industrial 8,273 1,844 1,503 11,620 2,683,585 2,695,205 Lease financing 3,677 45 1,512 5,234 905,355 910,589 Residential mortgage 23,833 2,429 19,202 45,464 3,542,327 3,587,791 Revolving mortgage 9,364 3,636 10,526 23,526 2,628,122 2,651,648 Construction and land development - noncommercial 2,885 — 1,122 4,007 239,107 243,114 Consumer 6,935 2,440 2,901 12,276 1,541,749 1,554,025 Other 46 47 129 222 281,263 281,485 Total non-PCI loans and leases $ 66,931 $ 15,972 $ 44,383 $ 127,286 $ 22,780,854 $ 22,908,140 December 31, 2017 30-59 days 60-89 days 90 days or greater Total past Current Total loans Non-PCI loans and leases: Construction and land development - commercial $ 491 $ 442 $ 357 $ 1,290 $ 667,925 $ 669,215 Commercial mortgage 12,288 2,375 6,490 21,153 9,707,869 9,729,022 Other commercial real estate 107 — 75 182 473,251 473,433 Commercial and industrial 6,694 1,510 1,266 9,470 2,720,937 2,730,407 Lease financing 2,983 167 973 4,123 890,678 894,801 Residential mortgage 27,886 8,064 21,901 57,851 3,465,935 3,523,786 Revolving mortgage 13,428 3,485 10,222 27,135 2,674,390 2,701,525 Construction and land development - noncommercial 7,154 108 1,379 8,641 239,648 248,289 Consumer 8,812 2,893 2,995 14,700 1,546,473 1,561,173 Other 188 6 133 327 301,849 302,176 Total non-PCI loans and leases $ 80,031 $ 19,050 $ 45,791 $ 144,872 $ 22,688,955 $ 22,833,827 The recorded investment, by class, in loans and leases on nonaccrual status, and loans and leases greater than 90 days past due and still accruing at March 31, 2018 and December 31, 2017 for non-PCI loans and leases, were as follows: March 31, 2018 December 31, 2017 (Dollars in thousands) Nonaccrual loans and leases Loans and leases > 90 days and accruing Nonaccrual loans and leases Loans and leases > 90 days and accruing Non-PCI loans and leases: Construction and land development - commercial $ 1,059 $ — $ 1,040 $ — Commercial mortgage 20,505 32 22,625 397 Other commercial real estate 616 — 916 — Commercial and industrial 2,928 721 2,884 428 Lease financing 1,687 — 1,992 — Residential mortgage 37,038 — 38,942 — Revolving mortgage 21,421 — 19,990 — Construction and land development - noncommercial 1,722 — 1,989 — Consumer 2,082 2,277 1,992 2,153 Other 202 — 164 — Total non-PCI loans and leases $ 89,260 $ 3,030 $ 92,534 $ 2,978 The following table provides changes in the carrying value of PCI loans during the three months ended March 31, 2018 and March 31, 2017 : (Dollars in thousands) 2018 2017 Balance at January 1 $ 762,998 $ 809,169 Fair value of acquired loans — 85,149 Accretion 17,973 19,351 Payments received and other changes, net (77,134 ) (64,853 ) Balance at March 31 $ 703,837 $ 848,816 Unpaid principal balance at March 31 $ 1,108,379 $ 1,155,034 The carrying value of loans on the cost recovery method was $1.3 million at March 31, 2018 and $1.1 million at December 31, 2017 . The cost recovery method is applied to loans when the timing of future cash flows is not reasonably estimable due to borrower nonperformance or uncertainty in the ultimate disposition of the asset. The recorded investment of PCI loans on nonaccrual status was $1.6 million and $624 thousand at March 31, 2018 and December 31, 2017 , respectively. During the three months ended March 31, 2018 and March 31, 2017 , accretion income on PCI loans was $18.0 million and $19.4 million , respectively. For PCI loans, improved credit loss expectations generally result in the reclassification of nonaccretable difference to accretable yield. Changes in expected cash flow not related to credit improvements or deterioration do not affect the nonaccretable difference. The following table documents changes to the amount of accretable yield for the first three months of 2018 and 2017 . (Dollars in thousands) 2018 2017 Balance at January 1 $ 316,679 $ 335,074 Additions from acquisitions — 16,653 Accretion (17,973 ) (19,351 ) Reclassifications (to) from nonaccretable difference (929 ) 11,277 Changes in expected cash flows that do not affect nonaccretable difference 11,568 (2,179 ) Balance at March 31 $ 309,345 $ 341,474

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Allowance	NOTE E - ALLOWANCE FOR LOAN AND LEASE LOSSES (ALLL) The following tables present the activity in the ALLL for non-PCI loan and lease losses by loan class for the three months ended March 31, 2018 and March 31, 2017 : Three months ended March 31, 2018 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Lease financing Other Residential mortgage Revolving mortgage Construction and land development - non- commercial Consumer Total Balance at January 1 $ 24,470 $ 45,005 $ 4,571 $ 53,697 $ 6,127 $ 4,689 $ 15,706 $ 22,436 $ 3,962 $ 31,204 $ 211,867 Provision 2,225 (1,365 ) (1,293 ) (425 ) 987 114 1,512 466 107 2,923 5,251 Charge-offs — (46 ) — (1,475 ) (854 ) (3 ) (806 ) (992 ) (182 ) (5,255 ) (9,613 ) Recoveries 23 239 145 1,219 41 42 77 194 26 1,309 3,315 Balance at March 31 $ 26,718 $ 43,833 $ 3,423 $ 53,016 $ 6,301 $ 4,842 $ 16,489 $ 22,104 $ 3,913 $ 30,181 $ 210,820 Three months ended March 31, 2017 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Lease financing Other Residential mortgage Revolving mortgage Construction and land development - non- commercial Consumer Total Balance at January 1 $ 28,877 $ 48,278 $ 3,269 $ 50,225 $ 5,907 $ 3,127 $ 14,447 $ 21,013 $ 1,596 $ 28,287 $ 205,026 Provision 2,536 6 304 3,592 575 517 1,351 550 (83 ) 1,728 11,076 Charge-offs (77 ) (37 ) (5 ) (3,253 ) (173 ) (123 ) (250 ) (825 ) — (3,966 ) (8,709 ) Recoveries 55 364 4 265 6 13 287 552 — 1,080 2,626 Balance at March 31 $ 31,391 $ 48,611 $ 3,572 $ 50,829 $ 6,315 $ 3,534 $ 15,835 $ 21,290 $ 1,513 $ 27,129 $ 210,019 The following tables present the allowance for non-PCI loan and lease losses and the recorded investment in loans, by loan class, based on impairment method as of March 31, 2018 and December 31, 2017 : March 31, 2018 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Lease financing Other Residential mortgage Revolving mortgage Construction and land development - non-commercial Consumer Total Allowance for loan and lease losses: ALLL for loans and leases individually evaluated for impairment $ 171 $ 3,521 $ 306 $ 621 $ 494 $ — $ 2,905 $ 1,053 $ 82 $ 713 $ 9,866 ALLL for loans and leases collectively evaluated for impairment 26,547 40,312 3,117 52,395 5,807 4,842 13,584 21,051 3,831 29,468 200,954 Total allowance for loan and lease losses $ 26,718 $ 43,833 $ 3,423 $ 53,016 $ 6,301 $ 4,842 $ 16,489 $ 22,104 $ 3,913 $ 30,181 $ 210,820 Loans and leases: Loans and leases individually evaluated for impairment $ 1,131 $ 70,277 $ 1,499 $ 7,611 $ 2,166 $ — $ 41,347 $ 25,525 $ 3,803 $ 2,591 $ 155,950 Loans and leases collectively evaluated for impairment 737,282 9,788,859 385,235 2,687,594 908,423 281,485 3,546,444 2,626,123 239,311 1,551,434 22,752,190 Total loan and leases $ 738,413 $ 9,859,136 $ 386,734 $ 2,695,205 $ 910,589 $ 281,485 $ 3,587,791 $ 2,651,648 $ 243,114 $ 1,554,025 $ 22,908,140 December 31, 2017 (Dollars in thousands) Construction Commercial Other Commercial and industrial Lease Other Residential Revolving Construction Consumer Total Allowance for loan and lease losses: ALLL for loans and leases individually evaluated for impairment $ 185 $ 3,648 $ 209 $ 665 $ 397 $ — $ 2,733 $ 1,085 $ 68 $ 738 $ 9,728 ALLL for loans and leases collectively evaluated for impairment 24,285 41,357 4,362 53,032 5,730 4,689 12,973 21,351 3,894 30,466 202,139 Total allowance for loan and lease losses $ 24,470 $ 45,005 $ 4,571 $ 53,697 $ 6,127 $ 4,689 $ 15,706 $ 22,436 $ 3,962 $ 31,204 $ 211,867 Loans and leases: Loans and leases individually evaluated for impairment $ 788 $ 73,655 $ 1,857 $ 7,974 $ 1,914 $ 521 $ 37,842 $ 23,770 $ 4,551 $ 2,774 $ 155,646 Loans and leases collectively evaluated for impairment 668,427 9,655,367 471,576 2,722,433 892,887 301,655 3,485,944 2,677,755 243,738 1,558,399 22,678,181 Total loan and leases $ 669,215 $ 9,729,022 $ 473,433 $ 2,730,407 $ 894,801 $ 302,176 $ 3,523,786 $ 2,701,525 $ 248,289 $ 1,561,173 $ 22,833,827 The following tables show the activity in the allowance for PCI loan losses by loan class for the three months ended March 31, 2018 and March 31, 2017 . Three months ended March 31, 2018 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Residential mortgage Revolving mortgage Construction and land development - noncommercial Consumer and other Total Balance at January 1 $ 142 $ 6,564 $ 221 $ 306 $ 2,117 $ 259 $ 193 $ 224 $ 10,026 Provision 310 1,608 (46 ) 13 264 209 (50 ) 46 2,354 Charge-offs — (84 ) — — — — — — (84 ) Recoveries — — — — — — — — — Balance at March 31 $ 452 $ 8,088 $ 175 $ 319 $ 2,381 $ 468 $ 143 $ 270 $ 12,296 Three months ended March 31, 2017 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Residential mortgage Revolving mortgage Construction and land development - noncommercial Consumer and other Total Balance at January 1 $ 483 $ 6,423 $ 502 $ 504 $ 4,818 $ 956 $ — $ 83 $ 13,769 Provision (186 ) (1,230 ) (158 ) (142 ) (545 ) (550 ) — (34 ) (2,845 ) Charge-offs — — — — — — — — — Recoveries — — — — — — — — — Balance at March 31 $ 297 $ 5,193 $ 344 $ 362 $ 4,273 $ 406 $ — $ 49 $ 10,924 The following tables show the ending balances of PCI loans and related allowance by class of loans as of March 31, 2018 and December 31, 2017 : March 31, 2018 (Dollars in thousands) Construction Commercial Other Commercial Residential Revolving Construction Consumer Total ALLL for loans acquired with deteriorated credit quality $ 452 $ 8,088 $ 175 $ 319 $ 2,381 $ 468 $ 143 $ 270 $ 12,296 Loans acquired with deteriorated credit quality 9,316 325,073 16,179 3,732 282,338 60,388 3,006 3,805 703,837 December 31, 2017 (Dollars in thousands) Construction Commercial Other Commercial Residential Revolving Construction Consumer Total ALLL for loans acquired with deteriorated credit quality $ 142 $ 6,564 $ 221 $ 306 $ 2,117 $ 259 $ 193 $ 224 $ 10,026 Loans acquired with deteriorated credit quality 10,135 358,103 17,124 6,374 299,318 63,908 4,163 3,873 762,998 As of March 31, 2018 and December 31, 2017 , $170.4 million and $279.8 million , respectively, in PCI loans experienced an adverse change in expected cash flows since the date of acquisition. The following tables provide information on non-PCI impaired loans and leases individually evaluated as of March 31, 2018 and December 31, 2017 including interest income recognized in the period during which the loans and leases were considered impaired. March 31, 2018 (Dollars in thousands) With a recorded allowance With no recorded allowance Total Unpaid Related allowance recorded Non-PCI impaired loans and leases: Construction and land development - commercial $ 740 $ 391 $ 1,131 $ 1,461 $ 171 Commercial mortgage 37,100 33,177 70,277 75,584 3,521 Other commercial real estate 1,086 413 1,499 1,614 306 Commercial and industrial 5,514 2,097 7,611 10,882 621 Lease financing 1,896 270 2,166 3,610 494 Residential mortgage 23,417 17,930 41,347 44,065 2,905 Revolving mortgage 9,998 15,527 25,525 27,948 1,053 Construction and land development - noncommercial 1,294 2,509 3,803 4,620 82 Consumer 1,744 847 2,591 2,872 713 Total non-PCI impaired loans and leases $ 82,789 $ 73,161 $ 155,950 $ 172,656 $ 9,866 December 31, 2017 (Dollars in thousands) With a With no Total Unpaid Related Non-PCI impaired loans and leases: Construction and land development - commercial $ 788 $ — $ 788 $ 1,110 $ 185 Commercial mortgage 39,135 34,520 73,655 78,936 3,648 Other commercial real estate 1,351 506 1,857 2,267 209 Commercial and industrial 6,326 1,648 7,974 10,475 665 Lease financing 1,890 24 1,914 2,571 397 Other — 521 521 521 — Residential mortgage 19,135 18,707 37,842 39,946 2,733 Revolving mortgage 5,875 17,895 23,770 25,941 1,085 Construction and land development - noncommercial 592 3,959 4,551 5,224 68 Consumer 2,107 667 2,774 3,043 738 Total non-PCI impaired loans and leases $ 77,199 $ 78,447 $ 155,646 $ 170,034 $ 9,728 Non-PCI impaired loans less than $500,000 that are collectively evaluated were $46.9 million and $49.1 million at March 31, 2018 and December 31, 2017 , respectively. The following tables show the average non-PCI impaired loan balance and the interest income recognized by loan class for the three months ended March 31, 2018 and March 31, 2017 : Three months ended March 31, 2018 Three months ended March 31, 2017 (Dollars in thousands) Average Interest income recognized Average Interest income recognized Non-PCI impaired loans and leases: Construction and land development - commercial $ 1,155 $ 11 $ 1,055 $ 12 Commercial mortgage 72,267 711 75,310 642 Other commercial real estate 1,713 11 1,584 8 Commercial and industrial 7,524 76 11,529 104 Lease financing 2,238 11 1,568 14 Other — — 196 2 Residential mortgage 38,724 275 32,963 253 Revolving mortgage 24,792 201 7,969 57 Construction and land development - noncommercial 4,104 48 2,605 33 Consumer 2,508 28 1,900 23 Total non-PCI impaired loans and leases $ 155,025 $ 1,372 $ 136,679 $ 1,148 Troubled Debt Restructurings BancShares accounts for certain loan modifications or restructurings as troubled debt restructurings (TDRs). In general, the modification or restructuring of a loan is considered a TDR if, for economic reasons or legal reasons related to a borrower's financial difficulties, a concession is granted to the borrower that creditors would not otherwise consider. Concessions may relate to the contractual interest rate, maturity date, payment structure or other actions. In accordance with GAAP, loans acquired under ASC 310-30, excluding pooled loans, are not initially considered to be TDRs, but can be classified as such if a modification is made subsequent to acquisition. Subsequent modification of a PCI loan accounted for in a pool that would otherwise meet the definition of a TDR is not reported, or accounted for, as a TDR since pooled PCI loans are excluded from the scope of TDR accounting. The following table provides a summary of total TDRs by accrual status. March 31, 2018 December 31, 2017 (Dollars in thousands) Accruing Nonaccruing Total Accruing Nonaccruing Total Commercial loans Construction and land development - $ 948 $ 253 $ 1,201 $ 4,089 $ 483 $ 4,572 Commercial mortgage 61,444 12,964 74,408 62,358 15,863 78,221 Other commercial real estate 950 491 1,441 1,012 788 1,800 Commercial and industrial 7,000 1,049 8,049 7,598 910 8,508 Lease financing 902 1,066 1,968 722 1,048 1,770 Other — — — 521 — 521 Total commercial TDRs 71,244 15,823 87,067 76,300 19,092 95,392 Noncommercial Residential mortgage 36,432 9,651 46,083 34,067 9,475 43,542 Revolving mortgage 19,267 5,364 24,631 17,673 5,180 22,853 Construction and land development - 2,914 183 3,097 — — — Consumer and other 2,063 529 2,592 2,351 423 2,774 Total noncommercial TDRs 60,676 15,727 76,403 54,091 15,078 69,169 Total TDRs $ 131,920 $ 31,550 $ 163,470 $ 130,391 $ 34,170 $ 164,561 The majority of TDRs are included in the special mention, substandard or doubtful credit grading categories, which results in more elevated loss expectations when projecting the expected cash flows that are used to determine the allowance for loan losses associated with these loans. When a restructured loan subsequently defaults, it is evaluated and downgraded if appropriate. The more severely graded the loan, the lower the estimated expected cash flows and the greater the allowance recorded. Further, all TDRs are individually evaluated for impairment through a review of collateral values or analysis of cash flows at least annually. The following table shows the accrual status of non-PCI and PCI TDRs. (Dollars in thousands) March 31, 2018 December 31, 2017 Accruing TDRs: PCI $ 18,380 $ 18,163 Non-PCI 113,540 112,228 Total accruing TDRs 131,920 130,391 Nonaccruing TDRs: PCI 250 272 Non-PCI 31,300 33,898 Total nonaccruing TDRs 31,550 34,170 All TDRs: PCI 18,630 18,435 Non-PCI 144,840 146,126 Total TDRs $ 163,470 $ 164,561 The following table provides the types of non-PCI TDRs made during the three months ended March 31, 2018 and March 31, 2017 , as well as a summary of loans that were modified as a TDR during the twelve month periods ended March 31, 2018 and March 31, 2017 that subsequently defaulted during the three months ended March 31, 2018 and March 31, 2017 . BancShares defines payment default as movement of the TDR to nonaccrual status, which is generally 90 days past due for TDRs, foreclosure or charge-off, whichever occurs first. Three months ended March 31, 2018 Three months ended March 31, 2017 All restructurings Restructurings with payment default All restructurings Restructurings with payment default (Dollars in thousands) Number of Loans Recorded investment at period end Number of Loans Recorded investment at period end Number of Loans Recorded investment at period end Number of Loans Recorded investment at period end Non-PCI loans and leases Loan term extension Commercial mortgage 1 $ 305 1 $ 305 — $ — — $ — Other commercial real estate — — — — — — 1 530 Commercial and industrial 3 549 — — 2 94 — — Residential mortgage — — — — 1 32 1 47 Revolving mortgage 1 57 — — — — — — Consumer 1 21 — — 2 14 — — Total loan term extension 6 932 1 305 5 140 2 577 Below market interest rate Construction and land development - commercial — — — — 1 60 — — Commercial mortgage 6 1,380 2 47 10 2,512 1 92 Other commercial real estate — — — — 1 4 — — Commercial and industrial 8 361 4 11 3 108 1 — Lease financing — — — — 3 839 2 769 Residential mortgage 22 2,189 10 1,277 30 1,543 15 824 Revolving mortgage 25 1,659 11 431 — — — — Construction and land development - noncommercial — — — — 2 412 — — Consumer 5 71 3 48 2 14 — — Other — — — — 1 143 — — Total below market interest rate 66 5,660 30 1,814 53 5,635 19 1,685 Discharged from bankruptcy Commercial mortgage 1 140 2 502 — — 1 190 Commercial and industrial 14 474 16 177 — — — — Lease financing 5 304 2 73 16 227 — — Residential mortgage 8 566 6 417 3 140 1 978 Revolving mortgage 5 440 4 193 4 99 9 649 Consumer 13 262 11 183 18 193 10 128 Total discharged from bankruptcy 46 2,186 41 1,545 41 659 21 1,945 Total non-PCI restructurings 118 $ 8,778 72 $ 3,664 99 $ 6,434 42 $ 4,207 The following table provides the types of PCI TDRs made during the three months ended March 31, 2018 and March 31, 2017 , as well as a summary of loans that were modified as a TDR during the twelve month periods ended March 31, 2018 and March 31, 2017 that subsequently defaulted during the three months ended March 31, 2018 and March 31, 2017 . Three months ended March 31, 2018 Three months ended March 31, 2017 All restructurings Restructurings with payment default All restructurings Restructurings with payment default (Dollars in thousands) Number of loans Recorded investment at period end Number of loans Recorded investment at period end Number of loans Recorded investment at period end Number of loans Recorded investment at period end PCI loans Interest only period provided Commercial and industrial 1 $ 644 — $ — — $ — — $ — Total interest only 1 644 — — — — — — Below market interest rate Residential mortgage — — — — 2 181 1 73 Total below market interest rate — — — — 2 181 1 73 Discharged from bankruptcy Commercial mortgage 2 1,627 2 1,627 — — — — Total discharged from bankruptcy 2 1,627 2 1,627 — — — — Total PCI restructurings 3 $ 2,271 2 $ 1,627 2 $ 181 1 $ 73 For the three months ended March 31, 2018 and March 31, 2017 , the pre-modification and post-modification outstanding recorded investments of loans modified as TDRs were not materially different.

Other Real Estate Owned

Other Real Estate Owned	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Real Estate Owned [Text Block]	NOTE F - OTHER REAL ESTATE OWNED (OREO) The following table explains changes in other real estate owned during the three months ended March 31, 2018 and March 31, 2017 . (Dollars in thousands) Total Balance at December 31, 2016 $ 61,231 Additions 5,822 Sales (8,845 ) Write-downs (1,717 ) Balance at March 31, 2017 $ 56,491 Balance at December 31, 2017 $ 51,097 Additions 6,582 Sales (8,380 ) Write-downs (1,210 ) Balance at March 31, 2018 $ 48,089 At March 31, 2018 and December 31, 2017 , BancShares had $16.5 million and $19.8 million , respectively, of foreclosed residential real estate property in OREO. The recorded investment in consumer mortgage loans collateralized by residential real estate property in the process of foreclosure was $30.6 million and $26.9 million at March 31, 2018 and December 31, 2017 , respectively.

FDIC Shared-Loss Receivable

FDIC Shared-Loss Receivable	3 Months Ended
	Mar. 31, 2018
FDIC Shared-Loss Receivable [Abstract]
FDIC Shared-Loss Receivable	FDIC SHARED-LOSS RECEIVABLE AND PAYABLE BancShares completed six FDIC-assisted transactions with shared-loss agreements during the period beginning in 2009 through 2011. Prior to its merger into BancShares, Bancorporation completed three FDIC-assisted transactions with shared-loss agreements: Georgian Bank (acquired in 2009); Williamsburg First National Bank (acquired in 2010); and Atlantic Bank & Trust (acquired in 2011). In 2016 and 2017, FCB entered into agreements with the FDIC to terminate the shared-loss agreements for Venture Bank, Temecula Valley Bank, Sun American Bank, Williamsburg First National Bank, Atlantic Bank & Trust and Colorado Capital Bank. As of March 31, 2018 , shared-loss agreements are still active for First Regional Bank (FRB), Georgian Bank (GB) and United Western Bank (UWB). Shared-loss protection remains for single family residential loans acquired from UWB and GB in the amount of $65.5 million . FRB remained in a recovery period, where any recoveries were shared with the FDIC, through March 2018. BancShares has a receivable from the FDIC for the expected reimbursement of losses on assets covered under the various shared-loss agreements. The shared-loss agreements are subject to interpretation by both the FDIC and BancShares, and disagreements may arise regarding coverage of losses, expenses and contingencies and requests for reimbursement may be delayed or disallowed for noncompliance. The following table provides changes in the FDIC shared-loss receivable for the three months ended March 31, 2018 and March 31, 2017 . Three months ended March 31 (Dollars in thousands) 2018 2017 Beginning balance $ 2,223 $ 4,172 Accretion (421 ) (600 ) Net cash payments to FDIC — 2,760 Post-acquisition adjustments 1,834 (2,591 ) Termination of FDIC shared-loss agreements — 240 Ending balance $ 3,636 $ 3,981 The shared-loss agreements for two FDIC-assisted transactions, FRB and UWB, include provisions related to payments that may be owed to the FDIC at the termination of the agreements (clawback liability) . The clawback liability represents a payment by BancShares to the FDIC if actual cumulative losses on acquired covered assets are lower than the cumulative losses originally estimated by the FDIC at the time of acquisition and is recorded in the Consolidated Balance Sheets as a payable to the FDIC under the relevant shared-loss agreements. As of March 31, 2018 and December 31, 2017 , the estimated clawback liability was $102.5 million and $101.3 million , respectively. The clawback liability payment dates for FRB and UWB are March 2020 and March 2021, respectively. The following table provides changes in the FDIC shared-loss payable for the three months ended March 31, 2018 and March 31, 2017 Three months ended March 31 (Dollars in thousands) 2018 2017 Beginning balance $ 101,342 $ 97,008 Accretion 992 954 Adjustments related to changes in assumptions 132 51 Ending balance $ 102,466 $ 98,013

Mortgage Servicing Rights

Mortgage Servicing Rights	3 Months Ended
	Mar. 31, 2018
Mortgage Servicing Rights [Abstract]
Transfers and Servicing of Financial Assets [Text Block]	MORTGAGE SERVICING RIGHTS Our portfolio of residential mortgage loans serviced for third parties was $2.85 billion and $2.81 billion as of March 31, 2018 and December 31, 2017 , respectively. These loans were originated by BancShares and sold to third parties on a non-recourse basis with servicing rights retained. These retained servicing rights are recorded as a servicing asset and reported in other intangible assets on the Consolidated Balance Sheets. The mortgage servicing rights are initially recorded at fair value and then carried at the lower of amortized cost or fair market value. The activity of the servicing asset for the three months ended March 31 , 2018 and 2017 is presented in the following table: Three months ended March 31 (Dollars in thousands) 2018 2017 Beginning balance $ 21,945 $ 20,415 Servicing rights originated 1,200 1,702 Amortization (1,486 ) (1,350 ) Valuation allowance reversal — 4 Ending balance $ 21,659 $ 20,771 The amortization expense related to mortgage servicing rights, included as a reduction of mortgage income in the Consolidated Statements of Income was $1.5 million and $1.4 million for the three months ended March 31, 2018 and 2017, respectively. Mortgage income for the three months ended March 31, 2018 did not include any impairment compared to an impairment reversal of $4 thousand for the three months ended March 31, 2017. Contractually specified mortgage servicing fees, late fees, and ancillary fees earned for the three months ended March 31, 2018 and 2017 were $1.9 million and $1.7 million , respectively, and reported in mortgage income in the Consolidated Statements of Income. Valuation of mortgage servicing rights is performed using a pooling methodology. Similar loans are pooled together and evaluated on a discounted earnings basis to determine the present value of future earnings. Key economic assumptions used to value mortgage servicing rights as of March 31, 2018 and December 31, 2017 were as follows: March 31, 2018 December 31, 2017 Discount rate - conventional fixed loans 9.74 % 9.41 % Discount rate - all loans excluding conventional fixed loans 10.74 % 10.41 % Weighted average constant prepayment rate 9.15 % 10.93 % Weighted average cost to service a loan $ 72.8 $ 64.03 The discount rate is based on the 10-year U.S. Treasury rate plus 700 basis points for conventional fixed loans and 800 basis points for all other loans. The 700 and 800 basis points are used as a risk premium when calculating the discount rate. The repayment rate is derived from the Public Securities Association Standard Prepayment model. The average cost to service a loan is based on the number of loans serviced and the total costs to service the loans.

Repurchase Agreements

Repurchase Agreements	3 Months Ended
	Mar. 31, 2018
Repurchase Agreements [Abstract]
Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block]	REPURCHASE AGREEMENTS BancShares utilizes securities sold under agreements to repurchase to facilitate the needs of customers and secure wholesale funding needs. Repurchase agreements are transactions whereby BancShares offers to sell to a counterparty an undivided interest in an eligible security at an agreed upon purchase price, and which obligates BancShares to repurchase the security on an agreed upon date at an agreed upon repurchase price plus interest at an agreed upon rate. Securities sold under agreements to repurchase are recorded at the amount of cash received in connection with the transaction and are generally reflected as short-term borrowings on the Consolidated Balance Sheets. BancShares monitors collateral levels on a continuous basis and maintains records of each transaction specifically describing the applicable security and the counterparty’s fractional interest in that security, and segregates the security from general assets in accordance with regulations governing custodial holdings of securities. The primary risk with repurchase agreements is market risk associated with the investments securing the transactions, as additional collateral may be required based on fair value changes of the underlying investments. Securities pledged as collateral under repurchase agreements are maintained with safekeeping agents. The carrying value of available for sale investment securities pledged as collateral under repurchase agreements was $535.6 million and $684.2 million at March 31, 2018 and December 31, 2017 , respectively. The remaining contractual maturity of the securities sold under agreements to repurchase by class of collateral pledged included in borrowings on the Consolidated Balance Sheets as of March 31, 2018 and December 31, 2017 is presented in the following tables. March 31, 2018 Remaining Contractual Maturity of the Agreements (Dollars in thousands) Overnight and continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements U.S. Treasury $ 522,207 $ — $ — $ — $ 522,207 Gross amount of recognized liabilities for repurchase agreements $ 522,207 December 31, 2017 Remaining Contractual Maturity of the Agreements Overnight and continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements U.S. Treasury $ 556,171 $ — $ 30,000 $ — $ 586,171 Gross amount of recognized liabilities for repurchase agreements $ 586,171

Estimated Fair Values

Estimated Fair Values	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Estimated Fair Values	ESTIMATED FAIR VALUES Fair value estimates are intended to represent the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants as of the measurement date. Where there is no active market for a financial instrument, BancShares has made estimates using discounted cash flows or other valuation techniques. Inputs used in these valuation techniques are subjective in nature, involve uncertainties and require significant judgment and therefore can only be derived within a range of precision. Accordingly, the derived fair value estimates presented below are not necessarily indicative of the amounts BancShares would realize in a current market exchange. ASC 820, Fair Value Measurements and Disclosures , indicates that assets and liabilities are recorded at fair value according to a fair value hierarchy comprised of three levels. The levels are based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The level within the fair value hierarchy for an asset or liability is based on the highest level of input that is significant to the fair value measurement (with Level 1 considered highest and Level 3 considered lowest). A brief description of each level follows: • Level 1 values are based on quoted prices for identical instruments in active markets. • Level 2 values are based on quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant assumptions are observable in the market. • Level 3 values are derived from valuation techniques in which one or more significant inputs or assumptions are not observable in the market. These unobservable inputs and assumptions reflect estimates that market participants would use in pricing the asset or liability. Valuation techniques include the use of discounted cash flow models and similar techniques. BancShares' management reviews any changes to its valuation methodologies to ensure they are appropriate and justified, and refines valuation methodologies as more market-based data becomes available. Transfers between levels of the fair value hierarchy are recognized at the end of the reporting period. There have been no changes during the three months ended March 31, 2018 and March 31, 2017. The methodologies used to estimate the fair value of financial assets and financial liabilities are discussed below: Investment securities available for sale . Investment securities available for sale are carried at fair value. U.S. Treasury, government agency and mortgage-backed securities are generally measured at fair value using a third party pricing service. The third party provider evaluates securities based on market data and utilizes pricing models that use a variety of inputs, such as benchmark yields, reported trades, broker-dealer quotes, issuer spreads, benchmark securities, bids and offers. These securities are generally classified as Level 2. Corporate bonds and trust preferred securities are generally measured at fair value based on indicative bids from broker-dealers and are not directly observable. These securities are considered Level 3. Marketable equity securities. Equity securities are measured at fair value using observable closing prices and the valuation also considers the amount of market activity by examining the trade volume of each security. Equity securities are classified as Level 1 if they are traded on a heavily active market and as Level 2 if the observable closing price is from a less than active market. Loans held for sale. Certain residential real estate loans are originated to be sold to investors are carried at fair value based on quoted market prices for similar types of loans. Accordingly, the inputs used to calculate fair value of originated residential real estate loans held for sale are classified as Level 2 inputs. Portfolio loans that are subsequently transferred to held for sale to be sold in the secondary market are carried at the lower of amortized cost or fair value. The fair value of the transferred portfolio loans is based on the quoted prices and is considered a Level 1 input. Net loans and leases (PCI and Non-PCI). Fair value is estimated based on discounted future cash flows using the current interest rates at which loans with similar terms would be made to borrowers of similar credit quality. The inputs used in the fair value measurements for loans and leases are considered Level 3 inputs. FHLB stock . The carrying amount of FHLB stock is a reasonable estimate of fair value as these securities are not readily marketable and are evaluated for impairment based on the ultimate recoverability of the par value. BancShares considers positive and negative evidence, including the profitability and asset quality of the issuer, dividend payment history and recent redemption experience, when determining the ultimate recoverability of the par value. BancShares believes its investment in FHLB stock is ultimately recoverable at par. The inputs used in the fair value measurement for the FHLB stock are considered Level 2 inputs. Mortgage servicing rights. Mortgage servicing rights are carried at the lower of amortized cost or market and are, therefore, carried at fair value only when fair value is less than the asset cost. The fair value of mortgage servicing rights is performed using a pooling methodology. Similar loans are pooled together and a model that relies on discount rates, estimates of prepayment rates and the weighted average cost to service the loans is used to determine the fair value. The inputs used in the fair value measurement for mortgage servicing rights are considered Level 3 inputs. Deposits. For non-time deposits, carrying value is a reasonable estimate of fair value. The fair value of time deposits is estimated by discounting future cash flows using the interest rates currently offered for deposits of similar remaining maturities. The inputs used in the fair value measurement for deposits are considered Level 2 inputs. Long-term obligations. For fixed rate trust preferred securities, the fair values are determined based on recent trades of the actual security if available. For other long-term obligations, fair values are estimated by discounting future cash flows using current interest rates for similar financial instruments. The inputs used in the fair value measurement for long-term obligations are considered Level 2 inputs. Payable to the FDIC for shared-loss agreements. The fair value of the payable to the FDIC for shared-loss agreements is determined by the projected cash flows based on expected payments to the FDIC in accordance with the shared-loss agreements. Cash flows are discounted using current discount rates to reflect the timing of the estimated amounts due to the FDIC. The inputs used in the fair value measurement for the payable to the FDIC are considered Level 3 inputs. Off-balance-sheet commitments and contingencies. Carrying amounts are reasonable estimates of the fair values for such financial instruments. Carrying amounts include unamortized fee income and, in some cases, reserves for any credit losses from those financial instruments. These amounts are not material to BancShares' financial position. For all other financial assets and financial liabilities, the carrying value is a reasonable estimate of the fair value as of March 31, 2018 and December 31, 2017 . The carrying value and fair value for these assets and liabilities are equivalent because they are relatively short term in nature and there is no interest rate or credit risk that would cause the fair value to differ from the carrying value. Cash and due from banks is classified on the fair value hierarchy as Level 1. Overnight investments, income earned not collected, short-term borrowings and accrued interest payable are considered Level 2. Lastly, the receivable from the FDIC for shared-loss agreements is designated as Level 3. (Dollars in thousands) March 31, 2018 December 31, 2017 Carrying value Fair value Carrying value Fair value Cash and due from banks $ 248,139 $ 248,139 $ 336,150 $ 336,150 Overnight investments 1,946,882 1,946,882 1,387,927 1,387,927 Investment securities available for sale 6,857,740 6,857,740 7,180,180 7,180,180 Investment securities held to maturity 74 79 76 81 Marketable equity securities 110,107 110,107 — — Loans held for sale 46,660 46,660 51,179 51,179 Net loans and leases 23,388,861 22,672,287 23,374,932 22,257,803 Receivable from the FDIC for shared-loss agreements 3,636 3,636 2,223 2,223 Income earned not collected 96,607 96,607 95,249 95,249 Federal Home Loan Bank stock 20,810 20,810 52,685 52,685 Mortgage servicing rights 21,659 27,512 21,945 26,170 Deposits 29,969,245 29,924,950 29,266,275 29,230,768 Short-term borrowings 554,758 554,758 693,807 693,807 Long-term obligations 194,413 203,061 870,240 852,112 Payable to the FDIC for shared-loss agreements 102,466 103,440 101,342 102,684 Accrued interest payable 1,498 1,498 3,952 3,952 Among BancShares' assets and liabilities, investment securities available for sale, marketable equity securities and loans held for sale are reported at their fair values on a recurring basis. For assets and liabilities carried at fair value on a recurring basis, the following table provides fair value information as of March 31, 2018 and December 31, 2017 . March 31, 2018 Fair value measurements using: (Dollars in thousands) Fair value Level 1 inputs Level 2 inputs Level 3 inputs Assets measured at fair value Investment securities available for sale U.S. Treasury $ 1,553,893 $ — $ 1,553,893 $ — Government agency 31,909 — 31,909 — Mortgage-backed securities 5,206,667 — 5,206,667 — Corporate bonds 59,653 — — 59,653 Other 5,618 — — 5,618 Total investment securities available for sale $ 6,857,740 $ — $ 6,792,469 $ 65,271 Marketable equity securities $ 110,107 $ 21,749 $ 88,358 $ — Loans held for sale $ 46,660 $ — $ 46,660 $ — December 31, 2017 Fair value measurements using: Fair value Level 1 inputs Level 2 inputs Level 3 inputs Assets measured at fair value Investment securities available for sale U.S. Treasury $ 1,657,864 $ — $ 1,657,864 $ — Government agency 8,670 — 8,670 — Mortgage-backed securities 5,340,756 — 5,340,756 — Equity securities 105,208 19,341 85,867 — Corporate bonds 59,963 — 59,963 — Other 7,719 — 7,719 — Total investment securities available for sale $ 7,180,180 $ 19,341 $ 7,160,839 $ — Loans held for sale $ 51,179 $ — $ 51,179 $ — For the three months ended March 31, 2018, there were transfers from Level 2 to Level 3 of $59.7 million and $5.6 million for corporate bonds and other investment securities available for sale, respectively. The transfers were due to a lack of observable inputs and trade activity for those securities. There were no transfers between levels for the three months ended March 31, 2017. The following table presents quantitative information about Level 3 fair value measurements for fair value on a recurring basis at March 31, 2018 and December 31, 2017 . (Dollars in thousands) March 31, 2018 Level 3 assets Valuation technique Significant unobservable input Fair Value Corporate bonds Indicative bid provided by broker Multiple factors, including but not limited to, current operations, financial condition, cash flows, and recently executed financing transactions related to the company $ 59,653 Other Indicative bid provided by broker Multiple factors, including but not limited to, current operations, financial condition, cash flows, and recently executed financing transactions related to the company 5,618 Fair Value Option BancShares has elected the fair value option for residential real estate loans originated to be sold. This election reduces certain timing differences in the Consolidated Statement of Income and better aligns with the management of the portfolio from a business perspective. The changes in fair value are recorded as a component of mortgage income and were a loss of $455 thousand and a gain of $3.2 million for the three months ended March 31, 2018 and March 31, 2017 , respectively. The following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for residential real estate originated for sale measured at fair value as of March 31, 2018 and December 31, 2017 . March 31, 2018 (Dollars in thousands) Fair Value Aggregate Unpaid Principal Balance Difference Originated loans held for sale $ 46,660 $ 45,732 $ 928 December 31, 2017 Fair Value Aggregate Unpaid Principal Balance Difference Originated loans held for sale $ 51,179 $ 49,796 $ 1,383 No originated loans held for sale were 90 or more days past due or on nonaccrual status as of March 31, 2018 or December 31, 2017 . Certain other assets are adjusted to their fair value on a nonrecurring basis, including impaired loans, OREO, and goodwill, which are periodically tested for impairment, and mortgage servicing rights, which are carried at the lower of amortized cost or market. Non-impaired loans held for investment, deposits, short-term borrowings and long-term obligations are not reported at fair value. Impaired loans are deemed to be at fair value if an associated allowance or current period charge-off has been recorded. The value of impaired loans is determined by either collateral valuations or discounted present value of the expected cash flow calculations. Collateral values are determined using appraisals or other third-party value estimates of the subject property with discounts generally between 6 and 11 percent applied for estimated holding and selling costs and other external factors that may impact the marketability of the property. Expected cash flows are determined using expected payment information at the individual loan level, discounted using the effective interest rate. The effective interest rate generally ranges between 2 and 18 percent. OREO that has been acquired or written down in the current year is deemed to be at fair value, which uses asset valuations. Asset values are determined using appraisals or other third-party value estimates of the subject property with discounts generally between 6 and 11 percent applied for estimated holding and selling costs and other external factors that may impact the marketability of the property. Changes to the value of the assets between scheduled valuation dates are monitored through continued communication with brokers and monthly reviews by the asset manager assigned to each asset. If there are any significant changes in the market or the subject property, valuations are adjusted or new appraisals ordered to ensure the reported values reflect the most current information. Mortgage servicing rights are carried at the lower of cost or market and are, therefore, carried at fair value only when fair value is less than the amortized asset cost. The fair value of mortgage servicing rights is performed using a pooling methodology. Similar loans are pooled together and a discounted cash flow model, which takes into consideration discount rates, prepayment rates, and the weighted average cost to service the loans, is used to determine the fair value. For financial assets and liabilities carried at fair value on a nonrecurring basis, the following table provides fair value information as of March 31, 2018 and December 31, 2017 . March 31, 2018 Fair value measurements using: (Dollars in thousands) Fair value Level 1 inputs Level 2 inputs Level 3 inputs Impaired loans $ 73,892 $ — $ — $ 73,892 Other real estate remeasured during current year 11,695 — — 11,695 December 31, 2017 Fair value measurements using: Fair value Level 1 inputs Level 2 inputs Level 3 inputs Impaired loans $ 72,539 $ — $ — $ 72,539 Other real estate remeasured during current year 40,167 — — 40,167 No financial liabilities were carried at fair value on a nonrecurring basis as of March 31, 2018 and December 31, 2017 .

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2018
Retirement Benefits, Description [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS BancShares sponsors noncontributory defined benefit pension plans for its qualifying employees (BancShares Plan) and former First Citizens Bancorporation, Inc. employees (Bancorporation Plan). The service cost component of net periodic benefit cost is included in salaries and wages while all other non-service cost components are included in other noninterest expense. BancShares Plan For the three months ended March 31, 2018 and 2017 , the components of net periodic benefit cost are as follows: Three months ended March 31 (Dollars in thousands) 2018 2017 Service cost $ 3,429 $ 3,376 Interest cost 7,057 7,380 Expected return on assets (11,957 ) (10,698 ) Amortization of prior service cost 20 52 Amortization of net actuarial loss 3,246 2,234 Net periodic benefit cost $ 1,795 $ 2,344 Bancorporation Plan For the three months ended March 31, 2018 and 2017 , the components of net periodic benefit cost are as follows: Three months ended March 31 (Dollars in thousands) 2018 2017 Service cost $ 662 $ 671 Interest cost 1,587 1,683 Expected return on assets (3,106 ) (2,796 ) Amortization of net actuarial loss 71 214 Net periodic benefit cost $ (786 ) $ (228 ) No contributions were made during the three months ended March 31, 2018 to the BancShares or Bancorporation pension plans. Management evaluates the need for its pension plan contributions on a periodic basis based upon numerous factors including, but not limited to, the funded status of and returns to the BancShares Plan and Bancorporation Plan, discount rates and the current economic environment.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES To meet the financing needs of its customers, BancShares and its subsidiaries have financial instruments with off-balance sheet risk. These financial instruments include commitments to extend credit, standby letters of credit and recourse obligations on mortgage loans sold. These instruments involve elements of credit, interest rate or liquidity risk. Commitments to extend credit are legally binding agreements to lend to customers. Commitments generally have fixed expiration dates or other termination clauses and may require payment of fees. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future liquidity requirements. Established credit standards control the credit risk exposure associated with these commitments. In some cases, BancShares requires that collateral be pledged to secure the commitment, including cash deposits, securities and other assets. Standby letters of credit are commitments guaranteeing performance of a customer to a third party. Those commitments are primarily issued to support public and private borrowing arrangements, and the fair value of those commitments is not material. To mitigate its risk, BancShares’ credit policies govern the issuance of standby letters of credit. The credit risk related to the issuance of these letters of credit is essentially the same as that involved in extending loans to clients and, therefore, these letters of credit are collateralized when necessary. The following table presents the commitments to extend credit and unfunded commitments as of March 31, 2018 and December 31, 2017 : (Dollars in thousands) March 31, 2018 December 31, 2017 Unused commitments to extend credit $ 9,994,802 $ 9,629,365 Standby letters of credit 81,059 81,530 Unfunded commitments for investments in affordable housing projects 63,803 61,819 Affordable housing project investments were $134.4 million and $128.0 million as of March 31, 2018 and December 31, 2017 , respectively, and are included in other assets on the Consolidated Balance Sheets. Pursuant to standard representations and warranties relating to residential mortgage loan sales sold on a non-recourse basis, contingent obligations exist for various events that may occur following the loan sale. If underwriting or documentation deficiencies are discovered at any point in the life of the loan or if the loan fails to perform per the terms of the loan purchase agreement, typically within 180 days from the date of sale, the investor may require BancShares to repurchase the loan or to repay a portion of the sale proceeds. Other liabilities included reserves of $867 thousand and $882 thousand as of March 31, 2018 and December 31, 2017 , respectively, for estimated losses arising from these standard representation and warranty provisions. BancShares and various subsidiaries have been named as defendants in legal actions arising from their normal business activities in which damages in various amounts are claimed. BancShares is also exposed to litigation risk relating to the prior business activities of banks from which assets were acquired and liabilities assumed in the various merger transactions. Although the amount of any ultimate liability with respect to such matters cannot be determined, in the opinion of management, any such liability will not have a material effect on BancShares’ consolidated financial statements.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME Accumulated other comprehensive loss included the following as of March 31, 2018 and December 31, 2017 : March 31, 2018 December 31, 2017 (Dollars in thousands) Accumulated other comprehensive loss Deferred tax benefit Accumulated other comprehensive loss, net of tax Accumulated other comprehensive loss Deferred tax benefit Accumulated other comprehensive loss, net of tax Unrealized losses on securities available for sale $ (157,460 ) $ (36,217 ) $ (121,243 ) $ (48,834 ) $ (17,889 ) $ (30,945 ) Funded status of defined benefit plans (141,662 ) (32,582 ) (109,080 ) (144,999 ) (53,650 ) (91,349 ) Total $ (299,122 ) $ (68,799 ) $ (230,323 ) $ (193,833 ) $ (71,539 ) $ (122,294 ) The following table highlights changes in accumulated other comprehensive (loss) income by component for the three months ended March 31, 2018 and March 31, 2017 : Three months ended March 31, 2018 (Dollars in thousands) Unrealized (losses) gains on securities available for sale 1 Defined benefit pension items 1 Total Beginning balance $ (30,945 ) $ (91,349 ) $ (122,294 ) Cumulative effect adjustments (29,752 ) (20,300 ) (50,052 ) Other comprehensive loss before reclassifications (60,546 ) — (60,546 ) Amounts reclassified from accumulated other comprehensive (loss) income — 2,569 2,569 Net current period other comprehensive (loss) income (60,546 ) 2,569 (57,977 ) Ending balance $ (121,243 ) $ (109,080 ) $ (230,323 ) Three months ended March 31, 2017 Unrealized (losses) gains on securities available for sale 1 Defined benefit pension items 1 Total Beginning balance $ (45,875 ) $ (89,317 ) $ (135,192 ) Other comprehensive income before reclassifications 22,677 — 22,677 Amounts reclassified from accumulated other comprehensive (loss) income 15 1,559 1,574 Net current period other comprehensive income 22,692 1,559 24,251 Ending balance $ (23,183 ) $ (87,758 ) $ (110,941 ) 1 All amounts are net of tax. Amounts in parentheses indicate debits. The following table presents the amounts reclassified from accumulated other comprehensive (loss) income and the line item affected in the statement where net income is presented for the three months ended March 31, 2018 and March 31, 2017 : (Dollars in thousands) Three months ended March 31, 2018 Details about accumulated other comprehensive income (loss) Amounts reclassified from accumulated other comprehensive income (loss) 1 Affected line item in the statement where net income is presented Amortization of defined benefit pension items Prior service costs $ (20 ) Salaries and wages Actuarial losses (3,317 ) Other (3,337 ) Income before income taxes 768 Income taxes $ (2,569 ) Net income Total reclassifications for the period $ (2,569 ) Three months ended March 31, 2017 Details about accumulated other comprehensive income (loss) Amounts reclassified from accumulated other comprehensive income (loss) 1 Affected line item in the statement where net income is presented Unrealized gains and losses on securities available for sale $ (24 ) Securities losses, net 9 Income taxes $ (15 ) Net income Amortization of defined benefit pension items Prior service costs $ (52 ) Salaries and wages Actuarial losses (2,448 ) Other (2,500 ) Income before income taxes 941 Income taxes $ (1,559 ) Net income Total reclassifications for the period $ (1,574 ) 1 Amounts in parentheses indicate debits to profit/loss.

Accounting Policies and Basis21

Accounting Policies and Basis of Presentation Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Reclassifications	Reclassifications In certain instances, amounts reported in prior years' consolidated financial statements have been reclassified to conform to the current financial statement presentation. Such reclassifications had no effect on previously reported cash flows, shareholders' equity or net income.
Use of Estimates	Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported. Actual results could differ from those estimates, and different assumptions in the application of these policies could result in material changes in BancShares' consolidated financial position, the consolidated results of its operations or related disclosures. Material estimates that are particularly susceptible to significant change include: • Allowance for loan and lease losses; • Fair value of financial instruments, including acquired assets and assumed liabilities; • Pension plan assumptions; • Cash flow estimates on purchased credit-impaired loans; • Goodwill and other intangible assets; • Federal Deposit Insurance Corporation (FDIC) shared-loss payable; and • Income tax assets, liabilities and expense
New Accounting Pronouncements	Recently Adopted Accounting Pronouncements FASB ASU 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10) The amendments in this ASU provide clarification on certain aspects related to the guidance issued in ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The areas for correction or improvement include (1) equity securities without a readily determinable fair value - discontinuation; (2) equity securities without a readily determinable fair value - adjustments; (3) forward contracts and purchased options; (4) presentation requirements for certain fair value option liabilities; (5) fair value option liabilities denominated in a foreign currency; and (6) transition guidance for equity securities without a readily determinable fair value. This ASU is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. Early adoption is permitted. We adopted the guidance effective in the first quarter of 2018. The adoption did not have a material impact on our consolidated financial position or consolidated results of operations. FASB ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This ASU requires a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the newly enacted federal corporate income tax rate in the Tax Cuts and Jobs Act of 2017 (Tax Act), which was enacted on December 22, 2017. The Tax Act included a reduction to the corporate income tax rate from 35 percent to 21 percent effective January 1, 2018. The amount of the reclassification would be the difference between the historical corporate income tax rate and the newly enacted 21 percent corporate income tax rate. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We adopted the guidance effective in the first quarter of 2018. The change in accounting principle was accounted for as a cumulative-effect adjustment to the balance sheet resulting in a $31.3 million increase to retained earnings and a corresponding decrease to AOCI on January 1, 2018. FASB ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This ASU requires employers to present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Employers will present the other components separately from the line item that includes the service cost. In addition, only the service cost component of net benefit cost is eligible for capitalization. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted the guidance effective in the first quarter of 2018. The adoption did not have a material impact on our consolidated financial position or consolidated results of operations. FASB ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This ASU addresses the diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The amendments in this ASU provide guidance on (1) debt prepayment or debt extinguishment costs; (2) settlement of zero-coupon debt instruments; (3) contingent consideration payments made after a business combination; (4) proceeds from the settlement of insurance claims; (5) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (6) distributions received from equity method investees; (7) beneficial interests in securitization transactions; and (8) separately identifiable cash flows and application of the predominance principle. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The guidance requires application using a retrospective transition method. We adopted the guidance effective in the first quarter of 2018. The adoption did not have any impact on our Consolidated Statements of Cash Flows. FASB ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10) : Recognition and Measurement of Financial Assets and Financial Liabilities This ASU addresses certain aspects of recognition, measurement, presentation and disclosure of certain financial instruments. The amendments in this ASU (1) require most equity investments to be measured at fair value with changes in fair value recognized in net income; (2) simplify the impairment assessment of equity investments without a readily determinable fair value; (3) eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet; (4) require public business entities to use exit price notion, rather than entry prices, when measuring fair value of financial instruments for disclosure purposes; (5) require separate presentation of financial assets and financial liabilities by measurement category and form of financial assets on the balance sheet or the accompanying notes to the financial statements; (6) require separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; and (7) state that a valuation allowance on deferred tax assets related to available-for-sale securities should be evaluated in combination with other deferred tax assets. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted the guidance effective in the first quarter of 2018. The change in accounting principle was accounted for as a cumulative-effect adjustment to the balance sheet resulting in an $18.7 million increase to retained earnings and a decrease to AOCI on January 1, 2018. With the adoption of this ASU equity securities can no longer be classified as available for sale, as such marketable equity securities will be disclosed as a separate line item on the balance sheet with changes in the fair value of equity securities reflected in net income. For equity investments without a readily determinable fair value, BancShares has elected to measure the equity investments using the measurement alternative which requires BancShares to make a qualitative assessment of whether the investment is impaired at each reporting period. Under the measurement alternative these investments will be measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for an identical or similar investment of the same issuer. If a qualitative assessment indicates that the investment is impaired, BancShares will estimate the investment's fair value in accordance with ASC 820 and, if the fair value is less than the investment's carrying value, recognize an impairment loss in net income equal to the difference between carrying value and fair value. Equity investments without a readily determinable fair value are recorded within other assets in the consolidated balance sheets. FASB ASU 2014-09, Revenue from Contracts with Customers (Topic 606) In May 2014, the FASB issued a standard on the recognition of revenue from contracts with customers with the core principle being for a company to recognize revenue to depict the transfer of goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard, which provides a five step model to determine when and how revenue is recognized, also results in enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively and improves guidance for multiple-element arrangements. Per ASU 2015-14, Deferral of the Effective Date , this guidance was deferred and is effective for fiscal periods beginning after December 15, 2017, including interim reporting periods within that reporting period. We adopted the guidance effective in the first quarter of 2018. Our revenue is comprised primarily of net interest income on financial assets and liabilities, which is explicitly excluded from the scope of the new guidance, and noninterest income. The contracts that are in scope of the guidance are primarily related to cardholder and merchant services income, service charges on deposit accounts, wealth management services income, other service charges and fees, insurance commissions, ATM income, sales of other real estate and other. Based on our overall assessment of revenue streams and review of related contracts affected by the ASU, the adoption of this guidance did not change the method in which we currently recognize revenue. We also completed an evaluation of the costs related to these revenue streams to determine whether such costs should be presented as expenses or contra-revenue (i.e., gross vs. net). Based on this evaluation, we determined that the classification of cardholder and merchant processing costs as well as expenses for cardholder reward programs should be netted against cardholder and merchant services income. We used the full retrospective method of adoption and restated the prior financial statements to net the cardholder and merchant processing costs against the related cardholder and merchant services income. These classification changes resulted in changes to both noninterest income and noninterest expense, however, there was no change to previously reported net income. Merchant processing expenses of $18.3 million have been reclassified and reported as a component of merchant services income for the three months ended March 31, 2017. Cardholder processing expenses of $6.8 million and cardholder reward programs expense of $2.5 million have been reclassified and reported as a component of cardholder services income for the three months ended March 31, 2017. Recently Issued Accounting Pronouncements FASB ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This ASU eliminates Step 2 from the goodwill impairment test. Under Step 2, an entity had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities (including unrecognized assets and liabilities) following the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. Instead, under the amendments in this ASU, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This ASU eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative test. This ASU will be effective for BancShares' annual or interim goodwill impairment tests for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We expect to adopt the guidance for our annual impairment test in fiscal year 2020. BancShares does not anticipate any impact to our consolidated financial position or consolidated results of operations as a result of the adoption. FASB ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This ASU eliminates the delayed recognition of the full amount of credit losses until the loss was probable of occurring and instead will reflect an entity's current estimate of all expected credit losses. The amendments in this ASU broaden the information that an entity must consider in developing its expected credit loss estimate for assets measured either collectively or individually. The ASU does not specify a method for measuring expected credit losses and allows an entity to apply methods that reasonably reflect its expectations of the credit loss estimate based on the entity's size, complexity and risk profile. In addition, the disclosures of credit quality indicators in relation to the amortized cost of financing receivables, a current disclosure requirement, are further disaggregated by year of origination. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018. We will adopt the guidance by the first quarter of 2020 with a cumulative-effect adjustment to retained earnings as of the beginning of the year of adoption. For BancShares, the standard will apply to loans, unfunded loan commitments and debt securities. We have formed a cross-functional team co-led by Corporate Finance and Risk Management with executive sponsorship and engaged a third party to assist with the adoption. The implementation team has developed a detailed project plan and is staying informed about the broader industry's perspective and insights, and identifying and researching key decision points. We have completed the readiness assessment and gap analysis related to data, modeling IT, accounting policy, controls and reporting which has enabled us to determine the areas of focus and estimate total body of work. Our current critical activities include model design, accounting policy development, data feasibility analysis, evaluation of reporting and disclosure solutions and completion of specific work stream project plans. We will continue to evaluate the impact the new standard will have on our consolidated financial statements as the final impact will be dependent, among other items, upon the loan portfolio composition and credit quality at the adoption date, as well as economic conditions, financial models used and forecasts at that time. FASB ASU 2016-02, Leases (Topic 842) This ASU increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The key difference between existing standards and this ASU is the requirement for lessees to recognize all lease contracts on their balance sheet. This ASU requires lessees to classify leases as either operating or finance leases, which are substantially similar to the current operating and capital leases classifications. The distinction between these two classifications under the new standard does not relate to balance sheet treatment, but relates to treatment in the statements of income and cash flows. Lessor guidance remains largely unchanged with the exception of how a lessor determines the appropriate lease classification for each lease to better align the lessor guidance with revised lessee classification guidance. The amendments in this ASU are effective for public business entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We will adopt during the first quarter of 2019. We expect an increase to the Consolidated Balance Sheets for right-of-use assets and associated lease liabilities, as well as resulting depreciation expense of the right-of-use assets and interest expense of the lease liabilities in the Consolidated Statements of Income, for arrangements previously accounted for as operating leases. Additionally, adding these assets to our balance sheet will impact our total risk-weighted assets used to determine our regulatory capital levels. Our impact analysis on this change in accounting principle estimates an increase to the Consolidated Balance Sheets for total lease liability ranging between $65.0 million and $85.0 million , as the initial gross up of both assets and liabilities. Capital is expected to be impacted by an estimated four to six basis points. These are preliminary estimates subject to change and will continue to be refined closer to adoption. Revenue Recognition The principles based standard requires disclosure of qualitative and quantitative information surrounding the amount, nature, timing and uncertainty of revenues and cash flows arising from contracts with customers. The core principle of the new standard is that revenue should be recognized when a company transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Descriptions of our noninterest revenue-generating activities that are within the scope of the new revenue ASU is broadly segregated as follows: Cardholder and Merchant Services - These represent interchange fees from customer debit and credit card transactions that are earned at the time a cardholder engages in a transaction with a merchant as well as fees charged to merchants for providing them the ability to accept and process the debit and credit card transaction. Revenue is recognized when the performance obligation has been met as it is satisfied upon the completion of the card transaction. Additionally, ASU 2014-09 requires us to report costs associated with cardholder and merchant services transactions to be netted against the fees from such transactions. Service Charges on Deposit Accounts - These deposit account-related fees represent monthly account maintenance and transaction-based service fees such as overdraft fees, stop payment fees and charges for issuing cashier's checks and money orders. For account maintenance services, revenue is recognized at the end of the statement period when our performance obligation has been satisfied. All other revenues from transaction-based services are recognized at a point in time when the performance obligation has been completed. Wealth Management Services - These primarily represent annuity fees, sales commissions, management fees, insurance sales, and trust and asset management fees. The performance obligation for wealth management services is the provision of services to place annuity products issued by the counterparty to investors, and the provision of services to manage the client’s assets, including brokerage custodial and other management services. Revenue is recognized over the period in which services are performed, are based on a percentage of the value of the assets under management/administration, and are fixed or variable based on account type, or are transaction-based. Other Service Charges and Fees - These include, but are not limited to, check cashing fees, international banking fees, internet banking fees, wire transfer fees and safe deposit fees. These fees are charged, and revenue is recognized, at the point in time the service being requested by the customer is provided thus satisfying our performance obligation. Insurance Commissions - These represent commissions earned on the issuance of insurance products and services. The performance obligation is generally satisfied upon the issuance of the insurance policy and revenue is recognized when the commission payment is remitted by the insurance carrier or policy holder depending on if the billing is performed by FCB or the carrier. ATM Income - These represent fees imposed on customers and non-customers for engaging in an ATM transaction. Revenue is recognized at the time of the transaction as the performance obligation of rendering the ATM service has been met. Sales of Other Real Estate - ORE property consists of foreclosed real estate used as collateral for loans, closed branches, land acquired and no longer intended for future use by FCB, and other real estate purchased for resale as ORE. Revenue is generally recognized on the date of sale where the performance obligation of providing access and transferring control of the specified ORE property to the buyer in good faith and good title is satisfied. This is recorded as a component of other noninterest income. Other - This consists of several forms of recurring revenue such as external rental income, parking income, FHLB dividends, and income earned on changes in the cash surrender value of bank-owned life insurance, all of which are outside the scope of ASU 2014-09. The remaining miscellaneous income is the result of immaterial transactions where revenue is recognized when, or as, the performance obligation is satisfied.

Business Combinations (Tables)

Business Combinations (Tables)	3 Months Ended
	Mar. 31, 2018
Business Acquisition [Line Items]
Loans acquired, cash flows expected

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2018
Gain (Loss) on Investments [Line Items]
Aggregate Values And Unrealized Gains And Losses Of Investment Securities	The amortized cost and fair value of investment securities classified as available for sale and held to maturity at March 31, 2018 and December 31, 2017 , are as follows: March 31, 2018 (Dollars in thousands) Cost Gross unrealized gains Gross unrealized losses Fair value Investment securities available for sale U.S. Treasury $ 1,557,991 $ — $ 4,098 $ 1,553,893 Government agency 32,006 12 109 31,909 Mortgage-backed securities 5,360,251 1,001 154,585 5,206,667 Corporate bonds 59,414 319 80 59,653 Other 5,538 80 — 5,618 Total investment securities available for sale $ 7,015,200 $ 1,412 $ 158,872 $ 6,857,740 December 31, 2017 Cost Gross Gross unrealized Fair Investment securities available for sale U.S. Treasury $ 1,658,410 $ — $ 546 $ 1,657,864 Government agency 8,695 15 40 8,670 Mortgage-backed securities 5,419,379 1,529 80,152 5,340,756 Equity securities 75,471 29,737 — 105,208 Corporate bonds 59,414 557 8 59,963 Other 7,645 256 182 7,719 Total investment securities available for sale $ 7,229,014 $ 32,094 $ 80,928 $ 7,180,180 March 31, 2018 Cost Gross Gross unrealized Fair Investment securities held to maturity Mortgage-backed securities $ 74 $ 5 $ — $ 79 December 31, 2017 Cost Gross Gross unrealized Fair Investment securities held to maturity Mortgage-backed securities $ 76 $ 5 $ — $ 81
Investment Securities Maturity Information	The following table provides the amortized cost and fair value by contractual maturity. Expected maturities will differ from contractual maturities on certain securities because borrowers and issuers may have the right to call or prepay obligations with or without prepayment penalties. Repayments of mortgage-backed securities are dependent on the repayments of the underlying loan balances. March 31, 2018 December 31, 2017 (Dollars in thousands) Cost Fair value Cost Fair value Investment securities available for sale Non-amortizing securities maturing in: One year or less $ 1,105,460 $ 1,103,291 $ 808,768 $ 808,301 One through five years 453,082 451,152 850,532 850,450 Five through 10 years 60,303 60,546 60,332 60,886 Over 10 years 36,104 36,084 14,532 14,579 Mortgage-backed securities 5,360,251 5,206,667 5,419,379 5,340,756 Equity securities — — 75,471 105,208 Total investment securities available for sale $ 7,015,200 $ 6,857,740 $ 7,229,014 $ 7,180,180 Investment securities held to maturity Mortgage-backed securities held to maturity $ 74 $ 79 $ 76 $ 81
Securities Gains (Losses)
Marketable Securities Gains (Losses)	The following table provides the realized and unrealized gains or losses on marketable equity securities for the three months ended March 31, 2018. (Dollars in thousands) Three months ended March 31, 2018 Marketable equity securities gains, net $ 971 Less net gains recognized on marketable equity securities sold 96 Unrealized gains recognized on marketable equity securities held $ 875
Investment Securities With Unrealized Losses	The following table provides information regarding securities available for sale with unrealized losses as of March 31, 2018 and December 31, 2017 . March 31, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair Unrealized Fair Unrealized Fair Unrealized Investment securities available for sale: U.S. Treasury $ 1,453,968 $ 4,049 $ 99,925 $ 49 $ 1,553,893 $ 4,098 Government agency 12,059 81 2,159 28 14,218 109 Mortgage-backed securities 2,404,338 58,606 2,535,662 95,979 4,940,000 154,585 Corporate bonds 9,950 80 — — 9,950 80 Total $ 3,880,315 $ 62,816 $ 2,637,746 $ 96,056 $ 6,518,061 $ 158,872 December 31, 2017 Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair Unrealized Investment securities available for sale: U.S. Treasury $ 1,408,166 $ 345 $ 249,698 $ 201 $ 1,657,864 $ 546 Government agency 848 12 2,527 28 3,375 40 Mortgage-backed securities 2,333,254 20,911 2,723,406 59,241 5,056,660 80,152 Corporate bonds 5,025 8 — — 5,025 8 Other 5,349 182 — — 5,349 182 Total $ 3,752,642 $ 21,458 $ 2,975,631 $ 59,470 $ 6,728,273 $ 80,928
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]	INVESTMENTS The amortized cost and fair value of investment securities classified as available for sale and held to maturity at March 31, 2018 and December 31, 2017 , are as follows: March 31, 2018 (Dollars in thousands) Cost Gross unrealized gains Gross unrealized losses Fair value Investment securities available for sale U.S. Treasury $ 1,557,991 $ — $ 4,098 $ 1,553,893 Government agency 32,006 12 109 31,909 Mortgage-backed securities 5,360,251 1,001 154,585 5,206,667 Corporate bonds 59,414 319 80 59,653 Other 5,538 80 — 5,618 Total investment securities available for sale $ 7,015,200 $ 1,412 $ 158,872 $ 6,857,740 December 31, 2017 Cost Gross Gross unrealized Fair Investment securities available for sale U.S. Treasury $ 1,658,410 $ — $ 546 $ 1,657,864 Government agency 8,695 15 40 8,670 Mortgage-backed securities 5,419,379 1,529 80,152 5,340,756 Equity securities 75,471 29,737 — 105,208 Corporate bonds 59,414 557 8 59,963 Other 7,645 256 182 7,719 Total investment securities available for sale $ 7,229,014 $ 32,094 $ 80,928 $ 7,180,180 March 31, 2018 Cost Gross Gross unrealized Fair Investment securities held to maturity Mortgage-backed securities $ 74 $ 5 $ — $ 79 December 31, 2017 Cost Gross Gross unrealized Fair Investment securities held to maturity Mortgage-backed securities $ 76 $ 5 $ — $ 81 As a result of adopting ASU 2016-01 in the first quarter of 2018, investments in marketable equity securities are no longer classified as investments available for sale. At March 31, 2018 and December 31, 2017, we had $110.1 million and $105.2 million , respectively, in marketable equity securities recorded at fair value. Prior to January 1, 2018 equity securities were classified as available for sale and stated at fair value with unrealized gains and losses reported in accumulated other comprehensive income. A cumulative-effect adjustment of $18.7 million was recorded on January 1, 2018 to reclassify the net unrealized gains from accumulated other comprehensive income to retained earnings with subsequent changes in fair value recognized in the Consolidated Statements of Income. Investments in mortgage-backed securities primarily represent securities issued by the Government National Mortgage Association, Federal National Mortgage Association and Federal Home Loan Mortgage Corporation. Investments in corporate bonds and marketable equity securities represent positions in securities of other financial institutions. Other investments include trust preferred securities of financial institutions. The following table provides the amortized cost and fair value by contractual maturity. Expected maturities will differ from contractual maturities on certain securities because borrowers and issuers may have the right to call or prepay obligations with or without prepayment penalties. Repayments of mortgage-backed securities are dependent on the repayments of the underlying loan balances. March 31, 2018 December 31, 2017 (Dollars in thousands) Cost Fair value Cost Fair value Investment securities available for sale Non-amortizing securities maturing in: One year or less $ 1,105,460 $ 1,103,291 $ 808,768 $ 808,301 One through five years 453,082 451,152 850,532 850,450 Five through 10 years 60,303 60,546 60,332 60,886 Over 10 years 36,104 36,084 14,532 14,579 Mortgage-backed securities 5,360,251 5,206,667 5,419,379 5,340,756 Equity securities — — 75,471 105,208 Total investment securities available for sale $ 7,015,200 $ 6,857,740 $ 7,229,014 $ 7,180,180 Investment securities held to maturity Mortgage-backed securities held to maturity $ 74 $ 79 $ 76 $ 81 There were no sales of investment securities available for sale for the three months ended March 31, 2018. Gross gains and gross losses on sales of investment securities available for sale were $3 thousand and $27 thousand , respectively for the three months ended March 31, 2017. The following table provides the realized and unrealized gains or losses on marketable equity securities for the three months ended March 31, 2018. (Dollars in thousands) Three months ended March 31, 2018 Marketable equity securities gains, net $ 971 Less net gains recognized on marketable equity securities sold 96 Unrealized gains recognized on marketable equity securities held $ 875 The following table provides information regarding securities available for sale with unrealized losses as of March 31, 2018 and December 31, 2017 . March 31, 2018 Less than 12 months 12 months or more Total (Dollars in thousands) Fair Unrealized Fair Unrealized Fair Unrealized Investment securities available for sale: U.S. Treasury $ 1,453,968 $ 4,049 $ 99,925 $ 49 $ 1,553,893 $ 4,098 Government agency 12,059 81 2,159 28 14,218 109 Mortgage-backed securities 2,404,338 58,606 2,535,662 95,979 4,940,000 154,585 Corporate bonds 9,950 80 — — 9,950 80 Total $ 3,880,315 $ 62,816 $ 2,637,746 $ 96,056 $ 6,518,061 $ 158,872 December 31, 2017 Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair Unrealized Investment securities available for sale: U.S. Treasury $ 1,408,166 $ 345 $ 249,698 $ 201 $ 1,657,864 $ 546 Government agency 848 12 2,527 28 3,375 40 Mortgage-backed securities 2,333,254 20,911 2,723,406 59,241 5,056,660 80,152 Corporate bonds 5,025 8 — — 5,025 8 Other 5,349 182 — — 5,349 182 Total $ 3,752,642 $ 21,458 $ 2,975,631 $ 59,470 $ 6,728,273 $ 80,928 Investment securities available for sale with an aggregate fair value of $2.64 billion and $2.98 billion had continuous unrealized losses for more than 12 months with a corresponding aggregate unrealized loss of $96.1 million and $59.5 million as of March 31, 2018 and December 31, 2017 , respectively. As of March 31, 2018 , 224 of these are government sponsored enterprise-issued mortgage-backed securities or government agency securities and 1 is a U.S. Treasury security. None of the unrealized losses identified as of March 31, 2018 or December 31, 2017 relate to the marketability of the securities or the issuers' ability to honor redemption obligations. Rather, the unrealized losses relate to changes in interest rates relative to when the debt securities were purchased. For all periods presented, BancShares had the ability and intent to retain these securities for a period of time sufficient to recover all unrealized losses. Therefore, none of the securities were deemed to be other than temporarily impaired. Debt securities having an aggregate carrying value of $3.83 billion at March 31, 2018 and $4.59 billion at December 31, 2017 were pledged as collateral to secure public funds on deposit and certain short-term borrowings, and for other purposes as required by law. On May 1, 2018, mortgage-backed securities with an amortized cost of $2.49 billion were transferred from investments available for sale to the held to maturity portfolio. At the time of transfer, the mortgage-backed securities had a fair value of $2.38 billion and a weighted average maturity of 13 years. FCB has the intent and ability to retain these securities until maturity.

Loans and Leases (Tables)

Loans and Leases (Tables)	3 Months Ended
	Mar. 31, 2018
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Loans And Leases Outstanding	Loans and leases outstanding included the following at March 31, 2018 and December 31, 2017 : (Dollars in thousands) March 31, 2018 December 31, 2017 Non-PCI loans and leases: Commercial: Construction and land development $ 738,413 $ 669,215 Commercial mortgage 9,859,136 9,729,022 Other commercial real estate 386,734 473,433 Commercial and industrial 2,695,205 2,730,407 Lease financing 910,589 894,801 Other 281,485 302,176 Total commercial loans 14,871,562 14,799,054 Noncommercial: Residential mortgage 3,587,791 3,523,786 Revolving mortgage 2,651,648 2,701,525 Construction and land development 243,114 248,289 Consumer 1,554,025 1,561,173 Total noncommercial loans 8,036,578 8,034,773 Total non-PCI loans and leases 22,908,140 22,833,827 PCI loans: Commercial: Construction and land development 9,316 10,135 Commercial mortgage 325,073 358,103 Other commercial real estate 16,179 17,124 Commercial and industrial 3,732 6,374 Other 1,628 1,683 Total commercial loans 355,928 393,419 Noncommercial: Residential mortgage 282,338 299,318 Revolving mortgage 60,388 63,908 Construction and land development 3,006 4,163 Consumer 2,177 2,190 Total noncommercial loans 347,909 369,579 Total PCI loans 703,837 762,998 Total loans and leases $ 23,611,977 $ 23,596,825
Composition Of The Loans And Leases Outstanding By Credit Quality Indicator	Non-PCI loans and leases outstanding at March 31, 2018 and December 31, 2017 by credit quality indicator are provided below: March 31, 2018 (Dollars in thousands) Non-PCI commercial loans and leases Grade: Construction and land Commercial Other Commercial and Lease financing Other Total non-PCI commercial loans and leases Pass $ 733,253 $ 9,661,079 $ 382,679 $ 2,476,337 $ 900,464 $ 278,367 $ 14,432,179 Special mention 483 81,680 1,187 37,571 3,347 1,107 125,375 Substandard 4,639 115,039 2,868 19,357 6,734 1,889 150,526 Doubtful — 1,338 — 836 — 72 2,246 Ungraded 38 — — 161,104 44 50 161,236 Total $ 738,413 $ 9,859,136 $ 386,734 $ 2,695,205 $ 910,589 $ 281,485 $ 14,871,562 December 31, 2017 Non-PCI commercial loans and leases Construction and land Commercial Other Commercial and Lease financing Other Total non-PCI commercial loans and leases Pass $ 665,197 $ 9,521,019 $ 468,942 $ 2,511,307 $ 883,779 $ 298,064 $ 14,348,308 Special mention 691 78,643 1,260 44,130 4,340 2,919 131,983 Substandard 3,327 128,848 3,224 18,617 6,585 1,193 161,794 Doubtful — 262 — 385 — — 647 Ungraded — 250 7 155,968 97 — 156,322 Total $ 669,215 $ 9,729,022 $ 473,433 $ 2,730,407 $ 894,801 $ 302,176 $ 14,799,054 March 31, 2018 Non-PCI noncommercial loans and leases (Dollars in thousands) Residential mortgage Revolving mortgage Construction and land development Consumer Total non-PCI noncommercial Current $ 3,542,327 $ 2,628,122 $ 239,107 $ 1,541,749 $ 7,951,305 30-59 days past due 23,833 9,364 2,885 6,935 43,017 60-89 days past due 2,429 3,636 — 2,440 8,505 90 days or greater past due 19,202 10,526 1,122 2,901 33,751 Total $ 3,587,791 $ 2,651,648 $ 243,114 $ 1,554,025 $ 8,036,578 December 31, 2017 Non-PCI noncommercial loans and leases Residential Revolving Construction Consumer Total non-PCI noncommercial Current $ 3,465,935 $ 2,674,390 $ 239,648 $ 1,546,473 $ 7,926,446 30-59 days past due 27,886 13,428 7,154 8,812 57,280 60-89 days past due 8,064 3,485 108 2,893 14,550 90 days or greater past due 21,901 10,222 1,379 2,995 36,497 Total $ 3,523,786 $ 2,701,525 $ 248,289 $ 1,561,173 $ 8,034,773 PCI loans outstanding at March 31, 2018 and December 31, 2017 by credit quality indicator are provided below: March 31, 2018 (Dollars in thousands) PCI commercial loans Grade: Construction and land development Commercial mortgage Other commercial real estate Commercial and industrial Other Total PCI commercial loans Pass $ 3,691 $ 157,187 $ 12,739 $ 1,642 $ 254 $ 175,513 Special mention 338 61,443 307 488 928 63,504 Substandard 4,231 101,734 2,615 1,492 446 110,518 Doubtful 1,056 4,709 518 81 — 6,364 Ungraded — — — 29 — 29 Total $ 9,316 $ 325,073 $ 16,179 $ 3,732 $ 1,628 $ 355,928 December 31, 2017 PCI commercial loans Construction Commercial Other Commercial Other Total PCI commercial Pass $ 1,817 $ 181,353 $ 13,830 $ 4,057 $ 275 $ 201,332 Special mention 320 61,295 323 374 945 63,257 Substandard 5,792 106,807 2,163 1,843 463 117,068 Doubtful 2,206 8,648 808 73 — 11,735 Ungraded — — — 27 — 27 Total $ 10,135 $ 358,103 $ 17,124 $ 6,374 $ 1,683 $ 393,419 March 31, 2018 PCI noncommercial loans (Dollars in thousands) Residential Revolving Construction Consumer Total PCI noncommercial Current $ 249,443 $ 53,885 $ 2,420 $ 2,095 $ 307,843 30-59 days past due 9,196 1,662 19 40 10,917 60-89 days past due 1,436 851 — — 2,287 90 days or greater past due 22,263 3,990 567 42 26,862 Total $ 282,338 $ 60,388 $ 3,006 $ 2,177 $ 347,909 December 31, 2017 PCI noncommercial loans Residential Revolving Construction Consumer Total PCI noncommercial Current $ 257,166 $ 55,871 $ 3,521 $ 2,074 $ 318,632 30-59 days past due 10,525 2,767 — 51 13,343 60-89 days past due 4,846 701 642 23 6,212 90 days or greater past due 26,781 4,569 — 42 31,392 Total $ 299,318 $ 63,908 $ 4,163 $ 2,190 $ 369,579
Aging Of The Outstanding Loans And Leases By Class Excluding Loans Impaired At Acquisition Date	The aging of the outstanding non-PCI loans and leases, by class, at March 31, 2018 and December 31, 2017 is provided in the table below. The calculation of days past due begins on the day after payment is due and includes all days through which all required interest or principal has not been paid. Loans and leases 30 days or less past due are considered current as various grace periods allow borrowers to make payments within a stated period after the due date and still remain in compliance with the loan agreement. March 31, 2018 (Dollars in thousands) 30-59 days past due 60-89 days past due 90 days or greater Total past due Current Total loans and leases Non-PCI loans and leases: Construction and land development - commercial $ 2,011 $ 771 $ 357 $ 3,139 $ 735,274 $ 738,413 Commercial mortgage 9,813 4,738 7,058 21,609 9,837,527 9,859,136 Other commercial real estate 94 22 73 189 386,545 386,734 Commercial and industrial 8,273 1,844 1,503 11,620 2,683,585 2,695,205 Lease financing 3,677 45 1,512 5,234 905,355 910,589 Residential mortgage 23,833 2,429 19,202 45,464 3,542,327 3,587,791 Revolving mortgage 9,364 3,636 10,526 23,526 2,628,122 2,651,648 Construction and land development - noncommercial 2,885 — 1,122 4,007 239,107 243,114 Consumer 6,935 2,440 2,901 12,276 1,541,749 1,554,025 Other 46 47 129 222 281,263 281,485 Total non-PCI loans and leases $ 66,931 $ 15,972 $ 44,383 $ 127,286 $ 22,780,854 $ 22,908,140 December 31, 2017 30-59 days 60-89 days 90 days or greater Total past Current Total loans Non-PCI loans and leases: Construction and land development - commercial $ 491 $ 442 $ 357 $ 1,290 $ 667,925 $ 669,215 Commercial mortgage 12,288 2,375 6,490 21,153 9,707,869 9,729,022 Other commercial real estate 107 — 75 182 473,251 473,433 Commercial and industrial 6,694 1,510 1,266 9,470 2,720,937 2,730,407 Lease financing 2,983 167 973 4,123 890,678 894,801 Residential mortgage 27,886 8,064 21,901 57,851 3,465,935 3,523,786 Revolving mortgage 13,428 3,485 10,222 27,135 2,674,390 2,701,525 Construction and land development - noncommercial 7,154 108 1,379 8,641 239,648 248,289 Consumer 8,812 2,893 2,995 14,700 1,546,473 1,561,173 Other 188 6 133 327 301,849 302,176 Total non-PCI loans and leases $ 80,031 $ 19,050 $ 45,791 $ 144,872 $ 22,688,955 $ 22,833,827
Recorded Investment, By Class, In Loans And Leases On Nonaccrual Status And Loans And Leases Greater Than 90 Days Past Due And Still Accruing	The recorded investment, by class, in loans and leases on nonaccrual status, and loans and leases greater than 90 days past due and still accruing at March 31, 2018 and December 31, 2017 for non-PCI loans and leases, were as follows: March 31, 2018 December 31, 2017 (Dollars in thousands) Nonaccrual loans and leases Loans and leases > 90 days and accruing Nonaccrual loans and leases Loans and leases > 90 days and accruing Non-PCI loans and leases: Construction and land development - commercial $ 1,059 $ — $ 1,040 $ — Commercial mortgage 20,505 32 22,625 397 Other commercial real estate 616 — 916 — Commercial and industrial 2,928 721 2,884 428 Lease financing 1,687 — 1,992 — Residential mortgage 37,038 — 38,942 — Revolving mortgage 21,421 — 19,990 — Construction and land development - noncommercial 1,722 — 1,989 — Consumer 2,082 2,277 1,992 2,153 Other 202 — 164 — Total non-PCI loans and leases $ 89,260 $ 3,030 $ 92,534 $ 2,978
Schedule of Contractually Required Payments Including Principal and Interest Expected Cash Flows to be Collected and Fair Values [Table Text Block]
Changes In Carrying Value Of PCI Loans	The following table provides changes in the carrying value of PCI loans during the three months ended March 31, 2018 and March 31, 2017 : (Dollars in thousands) 2018 2017 Balance at January 1 $ 762,998 $ 809,169 Fair value of acquired loans — 85,149 Accretion 17,973 19,351 Payments received and other changes, net (77,134 ) (64,853 ) Balance at March 31 $ 703,837 $ 848,816 Unpaid principal balance at March 31 $ 1,108,379 $ 1,155,034
Changes in Carrying Value of Accretable Yield for PCI Loans	The following table documents changes to the amount of accretable yield for the first three months of 2018 and 2017 . (Dollars in thousands) 2018 2017 Balance at January 1 $ 316,679 $ 335,074 Additions from acquisitions — 16,653 Accretion (17,973 ) (19,351 ) Reclassifications (to) from nonaccretable difference (929 ) 11,277 Changes in expected cash flows that do not affect nonaccretable difference 11,568 (2,179 ) Balance at March 31 $ 309,345 $ 341,474
Changes In Carrying Value of Accretable Yield for PCI Loans

Allowance for Loan and Lease 25

Allowance for Loan and Lease Losses (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Allowance for Loan and Lease Losses	The following tables provide information on non-PCI impaired loans and leases individually evaluated as of March 31, 2018 and December 31, 2017 including interest income recognized in the period during which the loans and leases were considered impaired. March 31, 2018 (Dollars in thousands) With a recorded allowance With no recorded allowance Total Unpaid Related allowance recorded Non-PCI impaired loans and leases: Construction and land development - commercial $ 740 $ 391 $ 1,131 $ 1,461 $ 171 Commercial mortgage 37,100 33,177 70,277 75,584 3,521 Other commercial real estate 1,086 413 1,499 1,614 306 Commercial and industrial 5,514 2,097 7,611 10,882 621 Lease financing 1,896 270 2,166 3,610 494 Residential mortgage 23,417 17,930 41,347 44,065 2,905 Revolving mortgage 9,998 15,527 25,525 27,948 1,053 Construction and land development - noncommercial 1,294 2,509 3,803 4,620 82 Consumer 1,744 847 2,591 2,872 713 Total non-PCI impaired loans and leases $ 82,789 $ 73,161 $ 155,950 $ 172,656 $ 9,866 December 31, 2017 (Dollars in thousands) With a With no Total Unpaid Related Non-PCI impaired loans and leases: Construction and land development - commercial $ 788 $ — $ 788 $ 1,110 $ 185 Commercial mortgage 39,135 34,520 73,655 78,936 3,648 Other commercial real estate 1,351 506 1,857 2,267 209 Commercial and industrial 6,326 1,648 7,974 10,475 665 Lease financing 1,890 24 1,914 2,571 397 Other — 521 521 521 — Residential mortgage 19,135 18,707 37,842 39,946 2,733 Revolving mortgage 5,875 17,895 23,770 25,941 1,085 Construction and land development - noncommercial 592 3,959 4,551 5,224 68 Consumer 2,107 667 2,774 3,043 738 Total non-PCI impaired loans and leases $ 77,199 $ 78,447 $ 155,646 $ 170,034 $ 9,728 Non-PCI impaired loans less than $500,000 that are collectively evaluated were $46.9 million and $49.1 million at March 31, 2018 and December 31, 2017 , respectively. The following tables show the average non-PCI impaired loan balance and the interest income recognized by loan class for the three months ended March 31, 2018 and March 31, 2017 : Three months ended March 31, 2018 Three months ended March 31, 2017 (Dollars in thousands) Average Interest income recognized Average Interest income recognized Non-PCI impaired loans and leases: Construction and land development - commercial $ 1,155 $ 11 $ 1,055 $ 12 Commercial mortgage 72,267 711 75,310 642 Other commercial real estate 1,713 11 1,584 8 Commercial and industrial 7,524 76 11,529 104 Lease financing 2,238 11 1,568 14 Other — — 196 2 Residential mortgage 38,724 275 32,963 253 Revolving mortgage 24,792 201 7,969 57 Construction and land development - noncommercial 4,104 48 2,605 33 Consumer 2,508 28 1,900 23 Total non-PCI impaired loans and leases $ 155,025 $ 1,372 $ 136,679 $ 1,148 The following tables present the activity in the ALLL for non-PCI loan and lease losses by loan class for the three months ended March 31, 2018 and March 31, 2017 : Three months ended March 31, 2018 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Lease financing Other Residential mortgage Revolving mortgage Construction and land development - non- commercial Consumer Total Balance at January 1 $ 24,470 $ 45,005 $ 4,571 $ 53,697 $ 6,127 $ 4,689 $ 15,706 $ 22,436 $ 3,962 $ 31,204 $ 211,867 Provision 2,225 (1,365 ) (1,293 ) (425 ) 987 114 1,512 466 107 2,923 5,251 Charge-offs — (46 ) — (1,475 ) (854 ) (3 ) (806 ) (992 ) (182 ) (5,255 ) (9,613 ) Recoveries 23 239 145 1,219 41 42 77 194 26 1,309 3,315 Balance at March 31 $ 26,718 $ 43,833 $ 3,423 $ 53,016 $ 6,301 $ 4,842 $ 16,489 $ 22,104 $ 3,913 $ 30,181 $ 210,820 Three months ended March 31, 2017 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Lease financing Other Residential mortgage Revolving mortgage Construction and land development - non- commercial Consumer Total Balance at January 1 $ 28,877 $ 48,278 $ 3,269 $ 50,225 $ 5,907 $ 3,127 $ 14,447 $ 21,013 $ 1,596 $ 28,287 $ 205,026 Provision 2,536 6 304 3,592 575 517 1,351 550 (83 ) 1,728 11,076 Charge-offs (77 ) (37 ) (5 ) (3,253 ) (173 ) (123 ) (250 ) (825 ) — (3,966 ) (8,709 ) Recoveries 55 364 4 265 6 13 287 552 — 1,080 2,626 Balance at March 31 $ 31,391 $ 48,611 $ 3,572 $ 50,829 $ 6,315 $ 3,534 $ 15,835 $ 21,290 $ 1,513 $ 27,129 $ 210,019 The following tables show the activity in the allowance for PCI loan losses by loan class for the three months ended March 31, 2018 and March 31, 2017 . Three months ended March 31, 2018 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Residential mortgage Revolving mortgage Construction and land development - noncommercial Consumer and other Total Balance at January 1 $ 142 $ 6,564 $ 221 $ 306 $ 2,117 $ 259 $ 193 $ 224 $ 10,026 Provision 310 1,608 (46 ) 13 264 209 (50 ) 46 2,354 Charge-offs — (84 ) — — — — — — (84 ) Recoveries — — — — — — — — — Balance at March 31 $ 452 $ 8,088 $ 175 $ 319 $ 2,381 $ 468 $ 143 $ 270 $ 12,296 Three months ended March 31, 2017 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Residential mortgage Revolving mortgage Construction and land development - noncommercial Consumer and other Total Balance at January 1 $ 483 $ 6,423 $ 502 $ 504 $ 4,818 $ 956 $ — $ 83 $ 13,769 Provision (186 ) (1,230 ) (158 ) (142 ) (545 ) (550 ) — (34 ) (2,845 ) Charge-offs — — — — — — — — — Recoveries — — — — — — — — — Balance at March 31 $ 297 $ 5,193 $ 344 $ 362 $ 4,273 $ 406 $ — $ 49 $ 10,924
Allocation of Allowance for Loan and Lease Losses	The following tables show the ending balances of PCI loans and related allowance by class of loans as of March 31, 2018 and December 31, 2017 : March 31, 2018 (Dollars in thousands) Construction Commercial Other Commercial Residential Revolving Construction Consumer Total ALLL for loans acquired with deteriorated credit quality $ 452 $ 8,088 $ 175 $ 319 $ 2,381 $ 468 $ 143 $ 270 $ 12,296 Loans acquired with deteriorated credit quality 9,316 325,073 16,179 3,732 282,338 60,388 3,006 3,805 703,837 December 31, 2017 (Dollars in thousands) Construction Commercial Other Commercial Residential Revolving Construction Consumer Total ALLL for loans acquired with deteriorated credit quality $ 142 $ 6,564 $ 221 $ 306 $ 2,117 $ 259 $ 193 $ 224 $ 10,026 Loans acquired with deteriorated credit quality 10,135 358,103 17,124 6,374 299,318 63,908 4,163 3,873 762,998 The following tables present the allowance for non-PCI loan and lease losses and the recorded investment in loans, by loan class, based on impairment method as of March 31, 2018 and December 31, 2017 : March 31, 2018 (Dollars in thousands) Construction and land development - commercial Commercial mortgage Other commercial real estate Commercial and industrial Lease financing Other Residential mortgage Revolving mortgage Construction and land development - non-commercial Consumer Total Allowance for loan and lease losses: ALLL for loans and leases individually evaluated for impairment $ 171 $ 3,521 $ 306 $ 621 $ 494 $ — $ 2,905 $ 1,053 $ 82 $ 713 $ 9,866 ALLL for loans and leases collectively evaluated for impairment 26,547 40,312 3,117 52,395 5,807 4,842 13,584 21,051 3,831 29,468 200,954 Total allowance for loan and lease losses $ 26,718 $ 43,833 $ 3,423 $ 53,016 $ 6,301 $ 4,842 $ 16,489 $ 22,104 $ 3,913 $ 30,181 $ 210,820 Loans and leases: Loans and leases individually evaluated for impairment $ 1,131 $ 70,277 $ 1,499 $ 7,611 $ 2,166 $ — $ 41,347 $ 25,525 $ 3,803 $ 2,591 $ 155,950 Loans and leases collectively evaluated for impairment 737,282 9,788,859 385,235 2,687,594 908,423 281,485 3,546,444 2,626,123 239,311 1,551,434 22,752,190 Total loan and leases $ 738,413 $ 9,859,136 $ 386,734 $ 2,695,205 $ 910,589 $ 281,485 $ 3,587,791 $ 2,651,648 $ 243,114 $ 1,554,025 $ 22,908,140 December 31, 2017 (Dollars in thousands) Construction Commercial Other Commercial and industrial Lease Other Residential Revolving Construction Consumer Total Allowance for loan and lease losses: ALLL for loans and leases individually evaluated for impairment $ 185 $ 3,648 $ 209 $ 665 $ 397 $ — $ 2,733 $ 1,085 $ 68 $ 738 $ 9,728 ALLL for loans and leases collectively evaluated for impairment 24,285 41,357 4,362 53,032 5,730 4,689 12,973 21,351 3,894 30,466 202,139 Total allowance for loan and lease losses $ 24,470 $ 45,005 $ 4,571 $ 53,697 $ 6,127 $ 4,689 $ 15,706 $ 22,436 $ 3,962 $ 31,204 $ 211,867 Loans and leases: Loans and leases individually evaluated for impairment $ 788 $ 73,655 $ 1,857 $ 7,974 $ 1,914 $ 521 $ 37,842 $ 23,770 $ 4,551 $ 2,774 $ 155,646 Loans and leases collectively evaluated for impairment 668,427 9,655,367 471,576 2,722,433 892,887 301,655 3,485,944 2,677,755 243,738 1,558,399 22,678,181 Total loan and leases $ 669,215 $ 9,729,022 $ 473,433 $ 2,730,407 $ 894,801 $ 302,176 $ 3,523,786 $ 2,701,525 $ 248,289 $ 1,561,173 $ 22,833,827
Troubled Debt Restructurings on Financing Receivables	The following table provides the types of non-PCI TDRs made during the three months ended March 31, 2018 and March 31, 2017 , as well as a summary of loans that were modified as a TDR during the twelve month periods ended March 31, 2018 and March 31, 2017 that subsequently defaulted during the three months ended March 31, 2018 and March 31, 2017 . BancShares defines payment default as movement of the TDR to nonaccrual status, which is generally 90 days past due for TDRs, foreclosure or charge-off, whichever occurs first. Three months ended March 31, 2018 Three months ended March 31, 2017 All restructurings Restructurings with payment default All restructurings Restructurings with payment default (Dollars in thousands) Number of Loans Recorded investment at period end Number of Loans Recorded investment at period end Number of Loans Recorded investment at period end Number of Loans Recorded investment at period end Non-PCI loans and leases Loan term extension Commercial mortgage 1 $ 305 1 $ 305 — $ — — $ — Other commercial real estate — — — — — — 1 530 Commercial and industrial 3 549 — — 2 94 — — Residential mortgage — — — — 1 32 1 47 Revolving mortgage 1 57 — — — — — — Consumer 1 21 — — 2 14 — — Total loan term extension 6 932 1 305 5 140 2 577 Below market interest rate Construction and land development - commercial — — — — 1 60 — — Commercial mortgage 6 1,380 2 47 10 2,512 1 92 Other commercial real estate — — — — 1 4 — — Commercial and industrial 8 361 4 11 3 108 1 — Lease financing — — — — 3 839 2 769 Residential mortgage 22 2,189 10 1,277 30 1,543 15 824 Revolving mortgage 25 1,659 11 431 — — — — Construction and land development - noncommercial — — — — 2 412 — — Consumer 5 71 3 48 2 14 — — Other — — — — 1 143 — — Total below market interest rate 66 5,660 30 1,814 53 5,635 19 1,685 Discharged from bankruptcy Commercial mortgage 1 140 2 502 — — 1 190 Commercial and industrial 14 474 16 177 — — — — Lease financing 5 304 2 73 16 227 — — Residential mortgage 8 566 6 417 3 140 1 978 Revolving mortgage 5 440 4 193 4 99 9 649 Consumer 13 262 11 183 18 193 10 128 Total discharged from bankruptcy 46 2,186 41 1,545 41 659 21 1,945 Total non-PCI restructurings 118 $ 8,778 72 $ 3,664 99 $ 6,434 42 $ 4,207 The following table provides the types of PCI TDRs made during the three months ended March 31, 2018 and March 31, 2017 , as well as a summary of loans that were modified as a TDR during the twelve month periods ended March 31, 2018 and March 31, 2017 that subsequently defaulted during the three months ended March 31, 2018 and March 31, 2017 . Three months ended March 31, 2018 Three months ended March 31, 2017 All restructurings Restructurings with payment default All restructurings Restructurings with payment default (Dollars in thousands) Number of loans Recorded investment at period end Number of loans Recorded investment at period end Number of loans Recorded investment at period end Number of loans Recorded investment at period end PCI loans Interest only period provided Commercial and industrial 1 $ 644 — $ — — $ — — $ — Total interest only 1 644 — — — — — — Below market interest rate Residential mortgage — — — — 2 181 1 73 Total below market interest rate — — — — 2 181 1 73 Discharged from bankruptcy Commercial mortgage 2 1,627 2 1,627 — — — — Total discharged from bankruptcy 2 1,627 2 1,627 — — — — Total PCI restructurings 3 $ 2,271 2 $ 1,627 2 $ 181 1 $ 73 For the three months ended March 31, 2018 and March 31, 2017 , the pre-modification and post-modification outstanding recorded investments of loans modified as TDRs were not materially different. The following table provides a summary of total TDRs by accrual status. March 31, 2018 December 31, 2017 (Dollars in thousands) Accruing Nonaccruing Total Accruing Nonaccruing Total Commercial loans Construction and land development - $ 948 $ 253 $ 1,201 $ 4,089 $ 483 $ 4,572 Commercial mortgage 61,444 12,964 74,408 62,358 15,863 78,221 Other commercial real estate 950 491 1,441 1,012 788 1,800 Commercial and industrial 7,000 1,049 8,049 7,598 910 8,508 Lease financing 902 1,066 1,968 722 1,048 1,770 Other — — — 521 — 521 Total commercial TDRs 71,244 15,823 87,067 76,300 19,092 95,392 Noncommercial Residential mortgage 36,432 9,651 46,083 34,067 9,475 43,542 Revolving mortgage 19,267 5,364 24,631 17,673 5,180 22,853 Construction and land development - 2,914 183 3,097 — — — Consumer and other 2,063 529 2,592 2,351 423 2,774 Total noncommercial TDRs 60,676 15,727 76,403 54,091 15,078 69,169 Total TDRs $ 131,920 $ 31,550 $ 163,470 $ 130,391 $ 34,170 $ 164,561 The majority of TDRs are included in the special mention, substandard or doubtful credit grading categories, which results in more elevated loss expectations when projecting the expected cash flows that are used to determine the allowance for loan losses associated with these loans. When a restructured loan subsequently defaults, it is evaluated and downgraded if appropriate. The more severely graded the loan, the lower the estimated expected cash flows and the greater the allowance recorded. Further, all TDRs are individually evaluated for impairment through a review of collateral values or analysis of cash flows at least annually. The following table shows the accrual status of non-PCI and PCI TDRs. (Dollars in thousands) March 31, 2018 December 31, 2017 Accruing TDRs: PCI $ 18,380 $ 18,163 Non-PCI 113,540 112,228 Total accruing TDRs 131,920 130,391 Nonaccruing TDRs: PCI 250 272 Non-PCI 31,300 33,898 Total nonaccruing TDRs 31,550 34,170 All TDRs: PCI 18,630 18,435 Non-PCI 144,840 146,126 Total TDRs $ 163,470 $ 164,561

Other Real Estate Owned (Tables

Other Real Estate Owned (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Changes in other real estate owned	The following table explains changes in other real estate owned during the three months ended March 31, 2018 and March 31, 2017 . (Dollars in thousands) Total Balance at December 31, 2016 $ 61,231 Additions 5,822 Sales (8,845 ) Write-downs (1,717 ) Balance at March 31, 2017 $ 56,491 Balance at December 31, 2017 $ 51,097 Additions 6,582 Sales (8,380 ) Write-downs (1,210 ) Balance at March 31, 2018 $ 48,089

FDIC Shared-Loss Receivable (Ta

FDIC Shared-Loss Receivable (Tables)	3 Months Ended
	Mar. 31, 2018
FDIC Shared-Loss Receivable [Abstract]
Changes In Payable to FDIC	Three months ended March 31 (Dollars in thousands) 2018 2017 Beginning balance $ 101,342 $ 97,008 Accretion 992 954 Adjustments related to changes in assumptions 132 51 Ending balance $ 102,466 $ 98,013
Changes in Receivable From FDIC	The following table provides changes in the FDIC shared-loss receivable for the three months ended March 31, 2018 and March 31, 2017 . Three months ended March 31 (Dollars in thousands) 2018 2017 Beginning balance $ 2,223 $ 4,172 Accretion (421 ) (600 ) Net cash payments to FDIC — 2,760 Post-acquisition adjustments 1,834 (2,591 ) Termination of FDIC shared-loss agreements — 240 Ending balance $ 3,636 $ 3,981

Mortgage Servicing Rights (Tabl

Mortgage Servicing Rights (Tables)	3 Months Ended
	Mar. 31, 2018
Mortgage Servicing Rights [Abstract]
Mortgage servicing rights	The activity of the servicing asset for the three months ended March 31 , 2018 and 2017 is presented in the following table: Three months ended March 31 (Dollars in thousands) 2018 2017 Beginning balance $ 21,945 $ 20,415 Servicing rights originated 1,200 1,702 Amortization (1,486 ) (1,350 ) Valuation allowance reversal — 4 Ending balance $ 21,659 $ 20,771
Mortgage servicing rights valuation allowance
Mortgage servicing rights economic assumptions	Valuation of mortgage servicing rights is performed using a pooling methodology. Similar loans are pooled together and evaluated on a discounted earnings basis to determine the present value of future earnings. Key economic assumptions used to value mortgage servicing rights as of March 31, 2018 and December 31, 2017 were as follows: March 31, 2018 December 31, 2017 Discount rate - conventional fixed loans 9.74 % 9.41 % Discount rate - all loans excluding conventional fixed loans 10.74 % 10.41 % Weighted average constant prepayment rate 9.15 % 10.93 % Weighted average cost to service a loan $ 72.8 $ 64.03

Repurchase Agreements (Tables)

Repurchase Agreements (Tables)	3 Months Ended
	Mar. 31, 2018
Repurchase Agreements [Abstract]
Schedule of Repurchase Agreements	The remaining contractual maturity of the securities sold under agreements to repurchase by class of collateral pledged included in borrowings on the Consolidated Balance Sheets as of March 31, 2018 and December 31, 2017 is presented in the following tables. March 31, 2018 Remaining Contractual Maturity of the Agreements (Dollars in thousands) Overnight and continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements U.S. Treasury $ 522,207 $ — $ — $ — $ 522,207 Gross amount of recognized liabilities for repurchase agreements $ 522,207 December 31, 2017 Remaining Contractual Maturity of the Agreements Overnight and continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Repurchase agreements U.S. Treasury $ 556,171 $ — $ 30,000 $ — $ 586,171 Gross amount of recognized liabilities for repurchase agreements $ 586,171

Estimated Fair Values (Tables)

Estimated Fair Values (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Level 3 Significant Unobservable Input Assumptions	(Dollars in thousands) March 31, 2018 Level 3 assets Valuation technique Significant unobservable input Fair Value Corporate bonds Indicative bid provided by broker Multiple factors, including but not limited to, current operations, financial condition, cash flows, and recently executed financing transactions related to the company $ 59,653 Other Indicative bid provided by broker Multiple factors, including but not limited to, current operations, financial condition, cash flows, and recently executed financing transactions related to the company 5,618
Estimated Fair Values For Certain Financial Assets And Financial Liabilities	For all other financial assets and financial liabilities, the carrying value is a reasonable estimate of the fair value as of March 31, 2018 and December 31, 2017 . The carrying value and fair value for these assets and liabilities are equivalent because they are relatively short term in nature and there is no interest rate or credit risk that would cause the fair value to differ from the carrying value. Cash and due from banks is classified on the fair value hierarchy as Level 1. Overnight investments, income earned not collected, short-term borrowings and accrued interest payable are considered Level 2. Lastly, the receivable from the FDIC for shared-loss agreements is designated as Level 3. (Dollars in thousands) March 31, 2018 December 31, 2017 Carrying value Fair value Carrying value Fair value Cash and due from banks $ 248,139 $ 248,139 $ 336,150 $ 336,150 Overnight investments 1,946,882 1,946,882 1,387,927 1,387,927 Investment securities available for sale 6,857,740 6,857,740 7,180,180 7,180,180 Investment securities held to maturity 74 79 76 81 Marketable equity securities 110,107 110,107 — — Loans held for sale 46,660 46,660 51,179 51,179 Net loans and leases 23,388,861 22,672,287 23,374,932 22,257,803 Receivable from the FDIC for shared-loss agreements 3,636 3,636 2,223 2,223 Income earned not collected 96,607 96,607 95,249 95,249 Federal Home Loan Bank stock 20,810 20,810 52,685 52,685 Mortgage servicing rights 21,659 27,512 21,945 26,170 Deposits 29,969,245 29,924,950 29,266,275 29,230,768 Short-term borrowings 554,758 554,758 693,807 693,807 Long-term obligations 194,413 203,061 870,240 852,112 Payable to the FDIC for shared-loss agreements 102,466 103,440 101,342 102,684 Accrued interest payable 1,498 1,498 3,952 3,952
Assets And Liabilities Carried At Fair Value On A Recurring Basis	For assets and liabilities carried at fair value on a recurring basis, the following table provides fair value information as of March 31, 2018 and December 31, 2017 . March 31, 2018 Fair value measurements using: (Dollars in thousands) Fair value Level 1 inputs Level 2 inputs Level 3 inputs Assets measured at fair value Investment securities available for sale U.S. Treasury $ 1,553,893 $ — $ 1,553,893 $ — Government agency 31,909 — 31,909 — Mortgage-backed securities 5,206,667 — 5,206,667 — Corporate bonds 59,653 — — 59,653 Other 5,618 — — 5,618 Total investment securities available for sale $ 6,857,740 $ — $ 6,792,469 $ 65,271 Marketable equity securities $ 110,107 $ 21,749 $ 88,358 $ — Loans held for sale $ 46,660 $ — $ 46,660 $ — December 31, 2017 Fair value measurements using: Fair value Level 1 inputs Level 2 inputs Level 3 inputs Assets measured at fair value Investment securities available for sale U.S. Treasury $ 1,657,864 $ — $ 1,657,864 $ — Government agency 8,670 — 8,670 — Mortgage-backed securities 5,340,756 — 5,340,756 — Equity securities 105,208 19,341 85,867 — Corporate bonds 59,963 — 59,963 — Other 7,719 — 7,719 — Total investment securities available for sale $ 7,180,180 $ 19,341 $ 7,160,839 $ — Loans held for sale $ 51,179 $ — $ 51,179 $ —
Fair Value Option	The following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for residential real estate originated for sale measured at fair value as of March 31, 2018 and December 31, 2017 . March 31, 2018 (Dollars in thousands) Fair Value Aggregate Unpaid Principal Balance Difference Originated loans held for sale $ 46,660 $ 45,732 $ 928 December 31, 2017 Fair Value Aggregate Unpaid Principal Balance Difference Originated loans held for sale $ 51,179 $ 49,796 $ 1,383 No originated loans held for sale were 90 or more days past due or on nonaccrual status as of March 31, 2018 or December 31, 2017 .
Assets And Liabilities Carried At Fair Value On A Nonrecurring Basis	For financial assets and liabilities carried at fair value on a nonrecurring basis, the following table provides fair value information as of March 31, 2018 and December 31, 2017 . March 31, 2018 Fair value measurements using: (Dollars in thousands) Fair value Level 1 inputs Level 2 inputs Level 3 inputs Impaired loans $ 73,892 $ — $ — $ 73,892 Other real estate remeasured during current year 11,695 — — 11,695 December 31, 2017 Fair value measurements using: Fair value Level 1 inputs Level 2 inputs Level 3 inputs Impaired loans $ 72,539 $ — $ — $ 72,539 Other real estate remeasured during current year 40,167 — — 40,167

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2018
BancShares Plan
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Benefit Costs	BancShares Plan For the three months ended March 31, 2018 and 2017 , the components of net periodic benefit cost are as follows: Three months ended March 31 (Dollars in thousands) 2018 2017 Service cost $ 3,429 $ 3,376 Interest cost 7,057 7,380 Expected return on assets (11,957 ) (10,698 ) Amortization of prior service cost 20 52 Amortization of net actuarial loss 3,246 2,234 Net periodic benefit cost $ 1,795 $ 2,344
Bancorporation Plan
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Benefit Costs	Bancorporation Plan For the three months ended March 31, 2018 and 2017 , the components of net periodic benefit cost are as follows: Three months ended March 31 (Dollars in thousands) 2018 2017 Service cost $ 662 $ 671 Interest cost 1,587 1,683 Expected return on assets (3,106 ) (2,796 ) Amortization of net actuarial loss 71 214 Net periodic benefit cost $ (786 ) $ (228 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Schedule of fair falue for off-balance sheet risks	The following table presents the commitments to extend credit and unfunded commitments as of March 31, 2018 and December 31, 2017 : (Dollars in thousands) March 31, 2018 December 31, 2017 Unused commitments to extend credit $ 9,994,802 $ 9,629,365 Standby letters of credit 81,059 81,530 Unfunded commitments for investments in affordable housing projects 63,803 61,819

Accumulated Other Comprehensi33

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule Of Accumulated Other Comprehensive Income (Loss)	Accumulated other comprehensive loss included the following as of March 31, 2018 and December 31, 2017 : March 31, 2018 December 31, 2017 (Dollars in thousands) Accumulated other comprehensive loss Deferred tax benefit Accumulated other comprehensive loss, net of tax Accumulated other comprehensive loss Deferred tax benefit Accumulated other comprehensive loss, net of tax Unrealized losses on securities available for sale $ (157,460 ) $ (36,217 ) $ (121,243 ) $ (48,834 ) $ (17,889 ) $ (30,945 ) Funded status of defined benefit plans (141,662 ) (32,582 ) (109,080 ) (144,999 ) (53,650 ) (91,349 ) Total $ (299,122 ) $ (68,799 ) $ (230,323 ) $ (193,833 ) $ (71,539 ) $ (122,294 ) The following table highlights changes in accumulated other comprehensive (loss) income by component for the three months ended March 31, 2018 and March 31, 2017 : Three months ended March 31, 2018 (Dollars in thousands) Unrealized (losses) gains on securities available for sale 1 Defined benefit pension items 1 Total Beginning balance $ (30,945 ) $ (91,349 ) $ (122,294 ) Cumulative effect adjustments (29,752 ) (20,300 ) (50,052 ) Other comprehensive loss before reclassifications (60,546 ) — (60,546 ) Amounts reclassified from accumulated other comprehensive (loss) income — 2,569 2,569 Net current period other comprehensive (loss) income (60,546 ) 2,569 (57,977 ) Ending balance $ (121,243 ) $ (109,080 ) $ (230,323 ) Three months ended March 31, 2017 Unrealized (losses) gains on securities available for sale 1 Defined benefit pension items 1 Total Beginning balance $ (45,875 ) $ (89,317 ) $ (135,192 ) Other comprehensive income before reclassifications 22,677 — 22,677 Amounts reclassified from accumulated other comprehensive (loss) income 15 1,559 1,574 Net current period other comprehensive income 22,692 1,559 24,251 Ending balance $ (23,183 ) $ (87,758 ) $ (110,941 ) 1 All amounts are net of tax.
Reclassification out of Accumulated Other Comprehensive Income	(Dollars in thousands) Three months ended March 31, 2018 Details about accumulated other comprehensive income (loss) Amounts reclassified from accumulated other comprehensive income (loss) 1 Affected line item in the statement where net income is presented Amortization of defined benefit pension items Prior service costs $ (20 ) Salaries and wages Actuarial losses (3,317 ) Other (3,337 ) Income before income taxes 768 Income taxes $ (2,569 ) Net income Total reclassifications for the period $ (2,569 ) Three months ended March 31, 2017 Details about accumulated other comprehensive income (loss) Amounts reclassified from accumulated other comprehensive income (loss) 1 Affected line item in the statement where net income is presented Unrealized gains and losses on securities available for sale $ (24 ) Securities losses, net 9 Income taxes $ (15 ) Net income Amortization of defined benefit pension items Prior service costs $ (52 ) Salaries and wages Actuarial losses (2,448 ) Other (2,500 ) Income before income taxes 941 Income taxes $ (1,559 ) Net income Total reclassifications for the period $ (1,574 ) 1 Amounts in parentheses indicate debits to profit/loss.

Accounting Policies and Basis34

Accounting Policies and Basis of Presentation Accounting Policies and Basis of Presentation (Recently Adopted Accounting Standards) (Details) $ in Millions	Dec. 22, 2017Rate	Mar. 31, 2018USD ($)basis_points	Mar. 31, 2017USD ($)	Dec. 31, 2017Rate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Federal Statutory Income Tax Rate, Percent | Rate	21.00%			35.00%
Merchant processing			$ 18.3
Cardholder processing			6.8
Cardholder reward programs			$ 2.5
Income tax ASU cumulative effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 31.3
Financial Instruments ASU cumulative effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		18.7
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		65
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 85
Capital basis points | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Capital Quantification | basis_points		4
Capital basis points | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Capital Quantification | basis_points		6

Business Combinations (Details)

Business Combinations (Details) - USD ($) $ / shares in Units, $ in Thousands	May 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jan. 13, 2017	Mar. 11, 2016
Business Acquisition [Line Items]
Assets		$ 34,436,437		$ 34,527,512
Loans and Leases		23,611,977		23,596,825
Deposits		29,969,245		29,266,275
PCI loans and leases					$ 0	$ 85,149
Gain on acquisitions		0	$ 12,017
Merger-related expenses		598	$ 833
Goodwill		150,601		$ 150,601
HomeBancorp Inc. [Member]
Business Acquisition [Line Items]
Assets		912,600
Loans and Leases		597,700
Deposits		$ 647,100
Subsequent Event [Member] | HomeBancorp Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price	$ 15.03
Business Combination, Consideration Transferred	$ 113,700

Business Combinations (Loans Ac

Business Combinations (Loans Acquired) (Details) - USD ($) $ in Thousands	Jan. 13, 2017	Mar. 11, 2016
Business Acquisition [Line Items]
PCI loans and leases	$ 0	$ 85,149

Investments (Aggregate Values a

Investments (Aggregate Values and Unrealized Gains and Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment securities available for sale
Cost	$ 7,015,200	$ 7,229,014
Gross Unrealized Gains	1,412	32,094
Gross Unrealized Losses	158,872	80,928
Fair Value	6,857,740	7,180,180
Investment securities held to maturity
Cost	74	76
U. S. Treasury
Investment securities available for sale
Cost	1,557,991	1,658,410
Gross Unrealized Gains	0	0
Gross Unrealized Losses	4,098	546
Fair Value	1,553,893	1,657,864
Government Agency
Investment securities available for sale
Cost	32,006	8,695
Gross Unrealized Gains	12	15
Gross Unrealized Losses	109	40
Fair Value	31,909	8,670
Mortgage Backed Securities
Investment securities available for sale
Cost	5,360,251	5,419,379
Gross Unrealized Gains	1,001	1,529
Gross Unrealized Losses	154,585	80,152
Fair Value	5,206,667	5,340,756
Investment securities held to maturity
Cost	74	76
Held To Maturity Securities Accumulated Unrecognized Holding Gain	5	5
Held To Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Fair Value	79	81
Equity Securities
Investment securities available for sale
Cost	0	75,471
Gross Unrealized Gains		29,737
Gross Unrealized Losses		0
Fair Value	0	105,208
Corporate Bonds
Investment securities available for sale
Cost	59,414	59,414
Gross Unrealized Gains	319	557
Gross Unrealized Losses	80	8
Fair Value	59,653	59,963
Other
Investment securities available for sale
Cost	5,538	7,645
Gross Unrealized Gains	80	256
Gross Unrealized Losses	0	182
Fair Value	$ 5,618	$ 7,719

Investments (Maturity Informati

Investments (Maturity Information) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment securities available for sale
Total investment securities available for sale, cost	$ 7,015,200	$ 7,229,014
Total investment securities available for sale, fair value	6,857,740	7,180,180
Investment securities held to maturity
Investment securities held to maturity	74	76
Debt Securities
Investment securities available for sale
Maturing in one year or less, cost	1,105,460	808,768
Maturing in one through five years, cost	453,082	850,532
Maturing in over ten years, cost	36,104	14,532
Maturing in one year or less, fair value	1,103,291	808,301
Maturing in one through five years, fair value	451,152	850,450
Maturing in over ten years, fair value	36,084	14,579
Investment securities held to maturity
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	60,303	60,332
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	60,546	60,886
Mortgage Backed Securities
Investment securities available for sale
Total investment securities available for sale, cost	5,360,251	5,419,379
Total investment securities available for sale, fair value	5,206,667	5,340,756
Investment securities held to maturity
Investment securities held to maturity	74	76
Fair Value	79	81
Equity Securities
Investment securities available for sale
Total investment securities available for sale, cost	0	75,471
Total investment securities available for sale, fair value	$ 0	$ 105,208

Investments (Unrealized Losses)

Investments (Unrealized Losses) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Unrealized Losses Related to Marketability of Securities or Issuer's Ability to Honor Redemption Obligations	$ 0	$ 0
Investment securities available for sale:
Fair Value, Less than 12 months	3,880,315,000	3,752,642,000
Unrealized Losses, Less than 12 months	62,816,000	21,458,000
Fair Value, 12 months or more	2,637,746,000	2,975,631,000
Unrealized Losses, Greater than 12 months	96,056,000	59,470,000
Fair Value, Total	6,518,061,000	6,728,273,000
Unrealized Losses, Total	158,872,000	80,928,000
U. S. Treasury
Investment securities available for sale:
Fair Value, Less than 12 months	1,453,968,000	1,408,166,000
Unrealized Losses, Less than 12 months	4,049,000	345,000
Fair Value, 12 months or more	99,925,000	249,698,000
Unrealized Losses, Greater than 12 months	49,000	201,000
Fair Value, Total	1,553,893,000	1,657,864,000
Unrealized Losses, Total	4,098,000	546,000
Government Agency
Investment securities available for sale:
Fair Value, Less than 12 months	12,059,000	848,000
Unrealized Losses, Less than 12 months	81,000	12,000
Fair Value, 12 months or more	2,159,000	2,527,000
Unrealized Losses, Greater than 12 months	28,000	28,000
Fair Value, Total	14,218,000	3,375,000
Unrealized Losses, Total	109,000	40,000
Mortgage Backed Securities
Investment securities available for sale:
Fair Value, Less than 12 months	2,404,338,000	2,333,254,000
Unrealized Losses, Less than 12 months	58,606,000	20,911,000
Fair Value, 12 months or more	2,535,662,000	2,723,406,000
Unrealized Losses, Greater than 12 months	95,979,000	59,241,000
Fair Value, Total	4,940,000,000	5,056,660,000
Unrealized Losses, Total	154,585,000	80,152,000
Corporate bonds
Investment securities available for sale:
Fair Value, Less than 12 months		5,025,000
Unrealized Losses, Less than 12 months		8,000
Fair Value, 12 months or more		0
Unrealized Losses, Greater than 12 months		0
Fair Value, Total		5,025,000
Unrealized Losses, Total		8,000
Equity Securities
Investment securities available for sale:
Unrealized Losses, Total		0
Corporate Bonds
Investment securities available for sale:
Fair Value, Less than 12 months	9,950,000
Unrealized Losses, Less than 12 months	80,000
Fair Value, 12 months or more	0
Unrealized Losses, Greater than 12 months	0
Fair Value, Total	9,950,000
Unrealized Losses, Total	80,000	8,000
Other
Investment securities available for sale:
Fair Value, Less than 12 months		5,349,000
Unrealized Losses, Less than 12 months		182,000
Fair Value, 12 months or more		0
Unrealized Losses, Greater than 12 months		0
Fair Value, Total		5,349,000
Unrealized Losses, Total	$ 0	$ 182,000

Investments (Securities Gains (

Investments (Securities Gains (Losses)) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Investments [Abstract]
Gross gains on sales of investment securities available for sale	$ 3
Gross losses on sales of investment securities available for sale	$ (27)

Investments Marketable Equity S

Investments Marketable Equity Securities Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Marketable Equity Securities Gains (Losses) [Abstract]
Marketable equity securities gain (loss), net	$ 971	$ 0
Net gains (losses) recognized on marketable equity securities sold	96
Unrealized gains (losses) recognized on marketable equity securities held	$ 875

Investments (Narrative) (Detail

Investments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)investments	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Schedule of Investments [Line Items]
Marketable equity securities	$ 110,107,000		$ 0
Unrealized Losses Related to Marketability of Securities or Issuer's Ability to Honor Redemption Obligations	0		0
Fair Value, 12 months or more in unrealized loss position	2,637,746,000		2,975,631,000
Unrealized Losses, Greater than 12 months	96,056,000		59,470,000
Investment value deemed to be OTTI	0	$ 0
Investment securities, aggregate carrying value, pledged as collateral	3,830,000,000		4,590,000,000
Investment securities available for sale	6,857,740,000		7,180,180,000
Equity Securities
Schedule of Investments [Line Items]
Investment securities available for sale	0		105,208,000
Mortgage Backed Securities
Schedule of Investments [Line Items]
Fair Value, 12 months or more in unrealized loss position	2,535,662,000		2,723,406,000
Unrealized Losses, Greater than 12 months	$ 95,979,000		59,241,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | investments	224
Investment securities available for sale	$ 5,206,667,000		5,340,756,000
U. S. Treasury
Schedule of Investments [Line Items]
Fair Value, 12 months or more in unrealized loss position	99,925,000		249,698,000
Unrealized Losses, Greater than 12 months	$ 49,000		201,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | investments	1
Investment securities available for sale	$ 1,553,893,000		$ 1,657,864,000
Financial Instruments ASU cumulative effect adjustment
Schedule of Investments [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 18,700,000

Loans and Leases (Narrative) (D

Loans and Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Threshold period past due for write-off of Business credit card loans (days)
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 6,260,000		$ 6,080,000
Advances from Federal Home Loan Banks	85,200		835,200
Federal Home Loan Bank Advances, Current Borrowing Capacity	6,170,000		5,240,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	1,500		1,700
Loans and Leases Receivable, Gross, Carrying Amount, Covered	65,500		67,800
Federal Reserve Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	2,160,000		2,080,000
Loans held for sale	46,660		51,179
Transfer of Portfolio Loans and Leases to Held-for-sale	0	$ 32,130
Proceeds From Sales of Loans	138,538	195,131
Proceeds from sales of portfolio loans	0	32,294
Gain (Loss) on sale of loans and leases	0	164
Non-PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	89,260		92,534
Accretion Income	2,900	3,200
PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	1,600		600
Accretion Income	18,000	$ 19,400
Guaranty Bank
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	13,300		14,200
Cordia Bancorp Inc.
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	2,500		2,700
Bancorporation
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	16,400		18,100
Federal Home Loan Bank of Atlanta
Financing Receivable, Recorded Investment [Line Items]
Loans Pledged as Collateral	9,110,000		8,750,000
Federal Reserve Bank
Financing Receivable, Recorded Investment [Line Items]
Loans Pledged as Collateral	$ 2,860,000		$ 2,770,000

Loans and Leases (Loans and Lea

Loans and Leases (Loans and Leases Outstanding) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Non-PCI loans	$ 22,908,140	$ 22,833,827
PCI loans	703,837	762,998	$ 848,816	$ 809,169
Total loans and leases	23,611,977	23,596,825
Commercial
Non-PCI loans	14,871,562	14,799,054
PCI loans	355,928	393,419
Commercial | Construction and land development
Non-PCI loans	738,413	669,215
PCI loans	9,316	10,135
Commercial | Mortgage
Non-PCI loans	9,859,136	9,729,022
PCI loans	325,073	358,103
Commercial | Other commercial real estate
Non-PCI loans	386,734	473,433
PCI loans	16,179	17,124
Commercial | Commercial and industrial
Non-PCI loans	2,695,205	2,730,407
PCI loans	3,732	6,374
Commercial | Lease financing
Non-PCI loans	910,589	894,801
Commercial | Other
Non-PCI loans	281,485	302,176
PCI loans	1,628	1,683
Noncommercial
Non-PCI loans	8,036,578	8,034,773
PCI loans	347,909	369,579
Noncommercial | Construction and land development
Non-PCI loans	243,114	248,289
PCI loans	3,006	4,163
Noncommercial | Mortgage
Non-PCI loans	3,587,791	3,523,786
PCI loans	282,338	299,318
Noncommercial | Revolving mortgage
Non-PCI loans	2,651,648	2,701,525
PCI loans	60,388	63,908
Noncommercial | Consumer
Non-PCI loans	1,554,025	1,561,173
PCI loans	$ 2,177	$ 2,190

Loans and Leases (Composition o

Loans and Leases (Composition of the Loans and Leases Outstanding By Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	$ 703,837	$ 762,998	$ 848,816	$ 809,169
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	14,871,562	14,799,054
PCI loans	355,928	393,419
Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	9,859,136	9,729,022
PCI loans	325,073	358,103
Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	386,734	473,433
PCI loans	16,179	17,124
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	2,695,205	2,730,407
PCI loans	3,732	6,374
Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	910,589	894,801
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	281,485	302,176
PCI loans	1,628	1,683
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	738,413	669,215
PCI loans	9,316	10,135
Commercial | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	14,432,179	14,348,308
PCI loans	175,513	201,332
Commercial | Pass | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	9,661,079	9,521,019
PCI loans	157,187	181,353
Commercial | Pass | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	382,679	468,942
PCI loans	12,739	13,830
Commercial | Pass | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	2,476,337	2,511,307
PCI loans	1,642	4,057
Commercial | Pass | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	900,464	883,779
Commercial | Pass | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	278,367	298,064
PCI loans	254	275
Commercial | Pass | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	733,253	665,197
PCI loans	3,691	1,817
Commercial | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	125,375	131,983
PCI loans	63,504	63,257
Commercial | Special Mention | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	81,680	78,643
PCI loans	61,443	61,295
Commercial | Special Mention | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,187	1,260
PCI loans	307	323
Commercial | Special Mention | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	37,571	44,130
PCI loans	488	374
Commercial | Special Mention | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	3,347	4,340
Commercial | Special Mention | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,107	2,919
PCI loans	928	945
Commercial | Special Mention | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	483	691
PCI loans	338	320
Commercial | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	150,526	161,794
PCI loans	110,518	117,068
Commercial | Substandard | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	115,039	128,848
PCI loans	101,734	106,807
Commercial | Substandard | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	2,868	3,224
PCI loans	2,615	2,163
Commercial | Substandard | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	19,357	18,617
PCI loans	1,492	1,843
Commercial | Substandard | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	6,734	6,585
Commercial | Substandard | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,889	1,193
PCI loans	446	463
Commercial | Substandard | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	4,639	3,327
PCI loans	4,231	5,792
Commercial | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	2,246	647
PCI loans	6,364	11,735
Commercial | Doubtful | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,338	262
PCI loans	4,709	8,648
Commercial | Doubtful | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	0	0
PCI loans	518	808
Commercial | Doubtful | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	836	385
PCI loans	81	73
Commercial | Doubtful | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	0	0
Commercial | Doubtful | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	72	0
PCI loans	0	0
Commercial | Doubtful | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	0	0
PCI loans	1,056	2,206
Commercial | Ungraded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	161,236	156,322
PCI loans	29	27
Commercial | Ungraded | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	0	250
PCI loans	0	0
Commercial | Ungraded | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	0	7
PCI loans	0	0
Commercial | Ungraded | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	161,104	155,968
PCI loans	29	27
Commercial | Ungraded | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	44	97
Commercial | Ungraded | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	50	0
PCI loans	0	0
Commercial | Ungraded | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	38	0
PCI loans	0	0
Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	347,909	369,579
Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	282,338	299,318
Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	3,006	4,163
Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	60,388	63,908
Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	2,177	2,190
Non-PCI Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	22,908,140	22,833,827
Past due loans	127,286	144,872
Current loans	22,780,854	22,688,955
Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	9,859,136	9,729,022
Past due loans	21,609	21,153
Current loans	9,837,527	9,707,869
Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	386,734	473,433
Past due loans	189	182
Current loans	386,545	473,251
Non-PCI Loans | Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	2,695,205	2,730,407
Past due loans	11,620	9,470
Current loans	2,683,585	2,720,937
Non-PCI Loans | Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	910,589	894,801
Past due loans	5,234	4,123
Current loans	905,355	890,678
Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	281,485	302,176
Past due loans	222	327
Current loans	281,263	301,849
Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	738,413	669,215
Past due loans	3,139	1,290
Current loans	735,274	667,925
Non-PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	8,036,578	8,034,773
Current loans	7,951,305	7,926,446
Non-PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	3,587,791	3,523,786
Past due loans	45,464	57,851
Current loans	3,542,327	3,465,935
Non-PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	243,114	248,289
Past due loans	4,007	8,641
Current loans	239,107	239,648
Non-PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	2,651,648	2,701,525
Past due loans	23,526	27,135
Current loans	2,628,122	2,674,390
Non-PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-PCI loans	1,554,025	1,561,173
Past due loans	12,276	14,700
Current loans	1,541,749	1,546,473
PCI Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	703,837	762,998
PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current loans	307,843	318,632
PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current loans	249,443	257,166
PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current loans	2,420	3,521
PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current loans	53,885	55,871
PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current loans	2,095	2,074
90 Days or greater | Non-PCI Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	44,383	45,791
90 Days or greater | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	7,058	6,490
90 Days or greater | Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	73	75
90 Days or greater | Non-PCI Loans | Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,503	1,266
90 Days or greater | Non-PCI Loans | Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,512	973
90 Days or greater | Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	129	133
90 Days or greater | Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	357	357
90 Days or greater | Non-PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	33,751	36,497
90 Days or greater | Non-PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	19,202	21,901
90 Days or greater | Non-PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,122	1,379
90 Days or greater | Non-PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	10,526	10,222
90 Days or greater | Non-PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,901	2,995
90 Days or greater | PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	26,862	31,392
90 Days or greater | PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	22,263	26,781
90 Days or greater | PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	567	0
90 Days or greater | PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	3,990	4,569
90 Days or greater | PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	42	42
60 to 89 Days past due | Non-PCI Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	15,972	19,050
60 to 89 Days past due | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	4,738	2,375
60 to 89 Days past due | Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	22	0
60 to 89 Days past due | Non-PCI Loans | Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,844	1,510
60 to 89 Days past due | Non-PCI Loans | Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	45	167
60 to 89 Days past due | Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	47	6
60 to 89 Days past due | Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	771	442
60 to 89 Days past due | Non-PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,505	14,550
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,429	8,064
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	0	108
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	3,636	3,485
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,440	2,893
60 to 89 Days past due | PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,287	6,212
60 to 89 Days past due | PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,436	4,846
60 to 89 Days past due | PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	0	642
60 to 89 Days past due | PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	851	701
60 to 89 Days past due | PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	0	23
30 to 59 Days past due | Non-PCI Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	66,931	80,031
30 to 59 Days past due | Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	9,813	12,288
30 to 59 Days past due | Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	94	107
30 to 59 Days past due | Non-PCI Loans | Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	8,273	6,694
30 to 59 Days past due | Non-PCI Loans | Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	3,677	2,983
30 to 59 Days past due | Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	46	188
30 to 59 Days past due | Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,011	491
30 to 59 Days past due | Non-PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	43,017	57,280
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	23,833	27,886
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	2,885	7,154
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	9,364	13,428
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	6,935	8,812
30 to 59 Days past due | PCI Loans | Noncommercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	10,917	13,343
30 to 59 Days past due | PCI Loans | Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	9,196	10,525
30 to 59 Days past due | PCI Loans | Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	19	0
30 to 59 Days past due | PCI Loans | Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	1,662	2,767
30 to 59 Days past due | PCI Loans | Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due loans	$ 40	$ 51

Loans and Leases (Aging Of The

Loans and Leases (Aging Of The Outstanding Loans and Leases By Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	$ 703,837	$ 762,998	$ 848,816	$ 809,169
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	355,928	393,419
Non-PCI loans	14,871,562	14,799,054
Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	9,316	10,135
Non-PCI loans	738,413	669,215
Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	325,073	358,103
Non-PCI loans	9,859,136	9,729,022
Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	16,179	17,124
Non-PCI loans	386,734	473,433
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	3,732	6,374
Non-PCI loans	2,695,205	2,730,407
Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI loans	910,589	894,801
Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	1,628	1,683
Non-PCI loans	281,485	302,176
Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	347,909	369,579
Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	3,006	4,163
Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	282,338	299,318
Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	60,388	63,908
Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	2,177	2,190
PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
PCI loans	703,837	762,998
PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current loans	307,843	318,632
PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current loans	2,420	3,521
PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current loans	249,443	257,166
PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current loans	53,885	55,871
PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current loans	2,095	2,074
Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	127,286	144,872
Current loans	22,780,854	22,688,955
Non-PCI loans	22,908,140	22,833,827
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	3,139	1,290
Current loans	735,274	667,925
Non-PCI loans	738,413	669,215
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	21,609	21,153
Current loans	9,837,527	9,707,869
Non-PCI loans	9,859,136	9,729,022
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	189	182
Current loans	386,545	473,251
Non-PCI loans	386,734	473,433
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	11,620	9,470
Current loans	2,683,585	2,720,937
Non-PCI loans	2,695,205	2,730,407
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	5,234	4,123
Current loans	905,355	890,678
Non-PCI loans	910,589	894,801
Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	222	327
Current loans	281,263	301,849
Non-PCI loans	281,485	302,176
Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current loans	7,951,305	7,926,446
Non-PCI loans	8,036,578	8,034,773
Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	4,007	8,641
Current loans	239,107	239,648
Non-PCI loans	243,114	248,289
Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	45,464	57,851
Current loans	3,542,327	3,465,935
Non-PCI loans	3,587,791	3,523,786
Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	23,526	27,135
Current loans	2,628,122	2,674,390
Non-PCI loans	2,651,648	2,701,525
Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	12,276	14,700
Current loans	1,541,749	1,546,473
Non-PCI loans	1,554,025	1,561,173
90 Days or greater | PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	26,862	31,392
90 Days or greater | PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	567	0
90 Days or greater | PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	22,263	26,781
90 Days or greater | PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	3,990	4,569
90 Days or greater | PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	42	42
90 Days or greater | Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	44,383	45,791
90 Days or greater | Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	357	357
90 Days or greater | Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	7,058	6,490
90 Days or greater | Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	73	75
90 Days or greater | Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	1,503	1,266
90 Days or greater | Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	1,512	973
90 Days or greater | Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	129	133
90 Days or greater | Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	33,751	36,497
90 Days or greater | Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	1,122	1,379
90 Days or greater | Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	19,202	21,901
90 Days or greater | Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	10,526	10,222
90 Days or greater | Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	2,901	2,995
60 to 89 Days past due | PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	2,287	6,212
60 to 89 Days past due | PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	0	642
60 to 89 Days past due | PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	1,436	4,846
60 to 89 Days past due | PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	851	701
60 to 89 Days past due | PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	0	23
60 to 89 Days past due | Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	15,972	19,050
60 to 89 Days past due | Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	771	442
60 to 89 Days past due | Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	4,738	2,375
60 to 89 Days past due | Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	22	0
60 to 89 Days past due | Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	1,844	1,510
60 to 89 Days past due | Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	45	167
60 to 89 Days past due | Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	47	6
60 to 89 Days past due | Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	8,505	14,550
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	0	108
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	2,429	8,064
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	3,636	3,485
60 to 89 Days past due | Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	2,440	2,893
30 to 59 Days past due | PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	10,917	13,343
30 to 59 Days past due | PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	19	0
30 to 59 Days past due | PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	9,196	10,525
30 to 59 Days past due | PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	1,662	2,767
30 to 59 Days past due | PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	40	51
30 to 59 Days past due | Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	66,931	80,031
30 to 59 Days past due | Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	2,011	491
30 to 59 Days past due | Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	9,813	12,288
30 to 59 Days past due | Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	94	107
30 to 59 Days past due | Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	8,273	6,694
30 to 59 Days past due | Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	3,677	2,983
30 to 59 Days past due | Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	46	188
30 to 59 Days past due | Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	43,017	57,280
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	2,885	7,154
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	23,833	27,886
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	9,364	13,428
30 to 59 Days past due | Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans	$ 6,935	$ 8,812

Loans and Leases (Recorded Inve

Loans and Leases (Recorded Investment, By Class, In Loans And Leases On Nonaccrual Status And Loans And Leases Greater Than 90 Days Past Due And Still Accruing) (Details) - Non-PCI Loans - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	$ 89,260	$ 92,534
Loans and leases greater than 90 days and accruing	3,030	2,978
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	1,059	1,040
Loans and leases greater than 90 days and accruing	0	0
Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	20,505	22,625
Loans and leases greater than 90 days and accruing	32	397
Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	616	916
Loans and leases greater than 90 days and accruing	0	0
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	2,928	2,884
Loans and leases greater than 90 days and accruing	721	428
Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	1,687	1,992
Loans and leases greater than 90 days and accruing	0	0
Noncommercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	1,722	1,989
Loans and leases greater than 90 days and accruing	0	0
Noncommercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	37,038	38,942
Loans and leases greater than 90 days and accruing	0	0
Noncommercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	202	164
Loans and leases greater than 90 days and accruing	0	0
Noncommercial | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	21,421	19,990
Loans and leases greater than 90 days and accruing	0	0
Noncommercial | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	2,082	1,992
Loans and leases greater than 90 days and accruing	$ 2,277	$ 2,153

Loans and Leases (Changes In Ca

Loans and Leases (Changes In Carrying Value Of Acquired Impaired Loans) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jan. 13, 2017	Mar. 11, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	$ 1,108,379	$ 1,155,034
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	762,998	809,169
Fair value of acquired loans				$ 0	$ 85,149
Accretion	17,973	19,351
Payments received and other changes, net	(77,134)	(64,853)
Ending balance	703,837	$ 848,816
Loans on the Cost Recovery Method
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans on cost recovery method	1,275		$ 1,100
Commercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	393,419
Ending balance	355,928
Noncommercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	369,579
Ending balance	347,909
Construction and land development | Commercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	10,135
Ending balance	9,316
Construction and land development | Noncommercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	4,163
Ending balance	3,006
Mortgage | Commercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	358,103
Ending balance	325,073
Mortgage | Noncommercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	299,318
Ending balance	282,338
Revolving mortgage | Noncommercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	63,908
Ending balance	60,388
Other commercial real estate | Commercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	17,124
Ending balance	16,179
Commercial and industrial | Commercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	6,374
Ending balance	3,732
Other | Commercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	1,683
Ending balance	1,628
Consumer | Noncommercial
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	2,190
Ending balance	2,177
PCI Loans
Carrying Value of Acquired Impaired Loans [Roll Forward]
Beginning balance	762,998
Ending balance	703,837
Nonaccruing	$ 1,600		$ 600

Loans and Leases (Changes In 49

Loans and Leases (Changes In Carrying Amount Of Accretable Yield) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Abstract]
Accretable yield	$ 309,345	$ 341,474	$ 316,679	$ 335,074
Additions from acquisitions	0	16,653
Accretion	(17,973)	(19,351)
Reclassifications from nonaccretable difference	(929)	11,277
Changes in expected cash flows that do not affect nonaccretable difference	$ 11,568	$ (2,179)

Loans and Leases Loans and Leas

Loans and Leases Loans and Leases (Schedule of Contractually Required Payments Including Principal and Interest, Expected Cash Flows to be Collected and Fair Values) (Details) - USD ($) $ in Thousands	Jan. 13, 2017	Mar. 11, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans and leases	$ 0	$ 85,149

Allowance for Loan and Lease 51

Allowance for Loan and Lease Losses (Summary of Activity In Allowance for Loan and Lease Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Net loans and leases			$ 23,388,861	$ 23,374,932
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			703,837	762,998	$ 848,816	$ 809,169
Allowance for loan and lease losses			223,116	221,893
Commercial
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			355,928	393,419
Commercial | Construction and land development
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			9,316	10,135
Commercial | Mortgage
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			325,073	358,103
Commercial | Other commercial real estate
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			16,179	17,124
Commercial | Commercial and industrial
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			3,732	6,374
Commercial | Other
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			1,628	1,683
Noncommercial
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			347,909	369,579
Noncommercial | Construction and land development
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			3,006	4,163
Noncommercial | Mortgage
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			282,338	299,318
Noncommercial | Revolving mortgage
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			60,388	63,908
Noncommercial | Consumer
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			2,177	2,190
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Related Allowance			9,866	9,728
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 211,867	$ 205,026
Provision for Loan, Lease, and Other Losses	5,251	11,076
Charge-offs	(9,613)	(8,709)
Recoveries	3,315	2,626
Ending balance	210,820	210,019
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			155,950	155,646
Loans and leases collectively evaluated for impairment			22,752,190	22,678,181
Net loans and leases			22,908,140	22,833,827
ALLL for loans and leases individually evaluated for impairment			9,866	9,728
ALLL for loans and leases collectively evaluated for impairment			200,954	202,139
Total allowance for loan and lease losses	211,867	205,026	210,820	211,867	210,019	205,026
Non-PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	24,470	28,877
Provision for Loan, Lease, and Other Losses	2,225	2,536
Charge-offs	0	(77)
Recoveries	23	55
Ending balance	26,718	31,391
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			1,131	788
Loans and leases collectively evaluated for impairment			737,282	668,427
Net loans and leases			738,413	669,215
ALLL for loans and leases individually evaluated for impairment			171	185
ALLL for loans and leases collectively evaluated for impairment			26,547	24,285
Total allowance for loan and lease losses	24,470	28,877	26,718	24,470	31,391	28,877
Non-PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	45,005	48,278
Provision for Loan, Lease, and Other Losses	(1,365)	6
Charge-offs	(46)	(37)
Recoveries	239	364
Ending balance	43,833	48,611
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			70,277	73,655
Loans and leases collectively evaluated for impairment			9,788,859	9,655,367
Net loans and leases			9,859,136	9,729,022
ALLL for loans and leases individually evaluated for impairment			3,521	3,648
ALLL for loans and leases collectively evaluated for impairment			40,312	41,357
Total allowance for loan and lease losses	45,005	48,278	43,833	45,005	48,611	48,278
Non-PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,571	3,269
Provision for Loan, Lease, and Other Losses	(1,293)	304
Charge-offs	0	(5)
Recoveries	145	4
Ending balance	3,423	3,572
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			1,499	1,857
Loans and leases collectively evaluated for impairment			385,235	471,576
Net loans and leases			386,734	473,433
ALLL for loans and leases individually evaluated for impairment			306	209
ALLL for loans and leases collectively evaluated for impairment			3,117	4,362
Total allowance for loan and lease losses	4,571	3,269	3,423	4,571	3,572	3,269
Non-PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	53,697	50,225
Provision for Loan, Lease, and Other Losses	(425)	3,592
Charge-offs	(1,475)	(3,253)
Recoveries	1,219	265
Ending balance	53,016	50,829
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			7,611	7,974
Loans and leases collectively evaluated for impairment			2,687,594	2,722,433
Net loans and leases			2,695,205	2,730,407
ALLL for loans and leases individually evaluated for impairment			621	665
ALLL for loans and leases collectively evaluated for impairment			52,395	53,032
Total allowance for loan and lease losses	53,697	50,225	53,016	53,697	50,829	50,225
Non-PCI Loans | Commercial | Lease financing
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,127	5,907
Provision for Loan, Lease, and Other Losses	987	575
Charge-offs	(854)	(173)
Recoveries	41	6
Ending balance	6,301	6,315
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			2,166	1,914
Loans and leases collectively evaluated for impairment			908,423	892,887
Net loans and leases			910,589	894,801
ALLL for loans and leases individually evaluated for impairment			494	397
ALLL for loans and leases collectively evaluated for impairment			5,807	5,730
Total allowance for loan and lease losses	6,127	5,907	6,301	6,127	6,315	5,907
Non-PCI Loans | Commercial | Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,689	3,127
Provision for Loan, Lease, and Other Losses	114	517
Charge-offs	(3)	(123)
Recoveries	42	13
Ending balance	4,842	3,534
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			0	521
Loans and leases collectively evaluated for impairment			281,485	301,655
Net loans and leases			281,485	302,176
ALLL for loans and leases individually evaluated for impairment			0	0
ALLL for loans and leases collectively evaluated for impairment			4,842	4,689
Total allowance for loan and lease losses	4,689	3,127	4,842	4,689	3,534	3,127
Non-PCI Loans | Noncommercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,962	1,596
Provision for Loan, Lease, and Other Losses	107	(83)
Charge-offs	(182)	0
Recoveries	26	0
Ending balance	3,913	1,513
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			3,803	4,551
Loans and leases collectively evaluated for impairment			239,311	243,738
Net loans and leases			243,114	248,289
ALLL for loans and leases individually evaluated for impairment			82	68
ALLL for loans and leases collectively evaluated for impairment			3,831	3,894
Total allowance for loan and lease losses	3,962	1,596	3,913	3,962	1,513	1,596
Non-PCI Loans | Noncommercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	15,706	14,447
Provision for Loan, Lease, and Other Losses	1,512	1,351
Charge-offs	(806)	(250)
Recoveries	77	287
Ending balance	16,489	15,835
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			41,347	37,842
Loans and leases collectively evaluated for impairment			3,546,444	3,485,944
Net loans and leases			3,587,791	3,523,786
ALLL for loans and leases individually evaluated for impairment			2,905	2,733
ALLL for loans and leases collectively evaluated for impairment			13,584	12,973
Total allowance for loan and lease losses	15,706	14,447	16,489	15,706	15,835	14,447
Non-PCI Loans | Noncommercial | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	22,436	21,013
Provision for Loan, Lease, and Other Losses	466	550
Charge-offs	(992)	(825)
Recoveries	194	552
Ending balance	22,104	21,290
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			25,525	23,770
Loans and leases collectively evaluated for impairment			2,626,123	2,677,755
Net loans and leases			2,651,648	2,701,525
ALLL for loans and leases individually evaluated for impairment			1,053	1,085
ALLL for loans and leases collectively evaluated for impairment			21,051	21,351
Total allowance for loan and lease losses	22,436	21,013	22,104	22,436	21,290	21,013
Non-PCI Loans | Noncommercial | Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	31,204	28,287
Provision for Loan, Lease, and Other Losses	2,923	1,728
Charge-offs	(5,255)	(3,966)
Recoveries	1,309	1,080
Ending balance	30,181	27,129
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment			2,591	2,774
Loans and leases collectively evaluated for impairment			1,551,434	1,558,399
Net loans and leases			1,554,025	1,561,173
ALLL for loans and leases individually evaluated for impairment			713	738
ALLL for loans and leases collectively evaluated for impairment			29,468	30,466
Total allowance for loan and lease losses	31,204	28,287	30,181	31,204	27,129	28,287
PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,026	13,769
Provision for Loan, Lease, and Other Losses	2,354	(2,845)
Charge-offs	(84)	0
Recoveries	0	0
Ending balance	12,296	10,924
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	10,026	13,769	12,296	10,026	10,924	13,769
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			703,837	762,998
PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	142	483
Provision for Loan, Lease, and Other Losses	310	(186)
Charge-offs	0	0
Recoveries	0	0
Ending balance	452	297
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	142	483	452	142	297	483
PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,564	6,423
Provision for Loan, Lease, and Other Losses	1,608	(1,230)
Charge-offs	(84)	0
Recoveries	0	0
Ending balance	8,088	5,193
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	6,564	6,423	8,088	6,564	5,193	6,423
PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	221	502
Provision for Loan, Lease, and Other Losses	(46)	(158)
Charge-offs	0	0
Recoveries	0	0
Ending balance	175	344
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	221	502	175	221	344	502
PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	306	504
Provision for Loan, Lease, and Other Losses	13	(142)
Charge-offs	0	0
Recoveries	0	0
Ending balance	319	362
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	306	504	319	306	362	504
PCI Loans | Noncommercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	193	0
Provision for Loan, Lease, and Other Losses	(50)	0
Charge-offs	0	0
Recoveries	0	0
Ending balance	143	0
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	193	0	143	193	0	0
PCI Loans | Noncommercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,117	4,818
Provision for Loan, Lease, and Other Losses	264	(545)
Charge-offs	0	0
Recoveries	0	0
Ending balance	2,381	4,273
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	2,117	4,818	2,381	2,117	4,273	4,818
PCI Loans | Noncommercial | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	259	956
Provision for Loan, Lease, and Other Losses	209	(550)
Charge-offs	0	0
Recoveries	0	0
Ending balance	468	406
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	259	956	468	259	406	956
PCI Loans | Noncommercial | Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	224	83
Provision for Loan, Lease, and Other Losses	46	(34)
Charge-offs	0	0
Recoveries	0	0
Ending balance	270	49
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	$ 224	$ 83	270	224	$ 49	$ 83
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality			$ 3,805	$ 3,873

Allowance for Loan and Lease 52

Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	$ 1,108,379	$ 1,155,034
Allowance for loan and lease losses	223,116		$ 221,893
Loans and Leases Receivable, Net Amount	23,388,861		23,374,932
Non-PCI impaired loans less than $500,000 collectively evaluated	46,900		49,100
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans which have adverse change in expected cash flows	170,400		279,800
Provision for Loan, Lease, and Other Losses	2,354	(2,845)
Financing Receivable, Allowance for Credit Losses, Write-downs	84	0
Recoveries	0	0
PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	310	(186)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	1,608	(1,230)
Financing Receivable, Allowance for Credit Losses, Write-downs	84	0
Recoveries	0	0
PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(46)	(158)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	13	(142)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(50)	0
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
PCI Loans | Noncommercial | Consumer and Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	46	(34)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	264	(545)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	209	(550)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	0	0
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total impaired noncovered loans and leases	155,950		155,646
Unpaid principal balance	172,656		170,034
Impaired Financing Receivable, Related Allowance	9,866		9,728
ALLL for loans and leases individually evaluated for impairment	9,866		9,728
Impaired Financing Receivable, with Related Allowance, Recorded Investment	82,789		77,199
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	73,161		78,447
Financing Receivable, Individually Evaluated for Impairment	155,950		155,646
Average balance	155,025	136,679
Interest income recognized	1,372	1,148
Provision for Loan, Lease, and Other Losses	5,251	11,076
Financing Receivable, Allowance for Credit Losses, Write-downs	9,613	8,709
Recoveries	3,315	2,626
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	200,954		202,139
Financing Receivable, Collectively Evaluated for Impairment	22,752,190		22,678,181
Loans and Leases Receivable, Net Amount	22,908,140		22,833,827
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,461		1,110
ALLL for loans and leases individually evaluated for impairment	171		185
Impaired Financing Receivable, with Related Allowance, Recorded Investment	740		788
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	391		0
Financing Receivable, Individually Evaluated for Impairment	1,131		788
Average balance	1,155	1,055
Interest income recognized	11	12
Provision for Loan, Lease, and Other Losses	2,225	2,536
Financing Receivable, Allowance for Credit Losses, Write-downs	0	77
Recoveries	23	55
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	26,547		24,285
Financing Receivable, Collectively Evaluated for Impairment	737,282		668,427
Loans and Leases Receivable, Net Amount	738,413		669,215
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	75,584		78,936
ALLL for loans and leases individually evaluated for impairment	3,521		3,648
Impaired Financing Receivable, with Related Allowance, Recorded Investment	37,100		39,135
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	33,177		34,520
Financing Receivable, Individually Evaluated for Impairment	70,277		73,655
Average balance	72,267	75,310
Interest income recognized	711	642
Provision for Loan, Lease, and Other Losses	(1,365)	6
Financing Receivable, Allowance for Credit Losses, Write-downs	46	37
Recoveries	239	364
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	40,312		41,357
Financing Receivable, Collectively Evaluated for Impairment	9,788,859		9,655,367
Loans and Leases Receivable, Net Amount	9,859,136		9,729,022
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,614		2,267
ALLL for loans and leases individually evaluated for impairment	306		209
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,086		1,351
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	413		506
Financing Receivable, Individually Evaluated for Impairment	1,499		1,857
Average balance	1,713	1,584
Interest income recognized	11	8
Provision for Loan, Lease, and Other Losses	(1,293)	304
Financing Receivable, Allowance for Credit Losses, Write-downs	0	5
Recoveries	145	4
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	3,117		4,362
Financing Receivable, Collectively Evaluated for Impairment	385,235		471,576
Loans and Leases Receivable, Net Amount	386,734		473,433
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	10,882		10,475
ALLL for loans and leases individually evaluated for impairment	621		665
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,514		6,326
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,097		1,648
Financing Receivable, Individually Evaluated for Impairment	7,611		7,974
Average balance	7,524	11,529
Interest income recognized	76	104
Provision for Loan, Lease, and Other Losses	(425)	3,592
Financing Receivable, Allowance for Credit Losses, Write-downs	1,475	3,253
Recoveries	1,219	265
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	52,395		53,032
Financing Receivable, Collectively Evaluated for Impairment	2,687,594		2,722,433
Loans and Leases Receivable, Net Amount	2,695,205		2,730,407
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3,610		2,571
ALLL for loans and leases individually evaluated for impairment	494		397
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,896		1,890
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	270		24
Financing Receivable, Individually Evaluated for Impairment	2,166		1,914
Average balance	2,238	1,568
Interest income recognized	11	14
Provision for Loan, Lease, and Other Losses	987	575
Financing Receivable, Allowance for Credit Losses, Write-downs	854	173
Recoveries	41	6
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	5,807		5,730
Financing Receivable, Collectively Evaluated for Impairment	908,423		892,887
Loans and Leases Receivable, Net Amount	910,589		894,801
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance			521
ALLL for loans and leases individually evaluated for impairment	0		0
Impaired Financing Receivable, with Related Allowance, Recorded Investment			0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment			521
Financing Receivable, Individually Evaluated for Impairment	0		521
Average balance	0	196
Interest income recognized	0	2
Provision for Loan, Lease, and Other Losses	114	517
Financing Receivable, Allowance for Credit Losses, Write-downs	3	123
Recoveries	42	13
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4,842		4,689
Financing Receivable, Collectively Evaluated for Impairment	281,485		301,655
Loans and Leases Receivable, Net Amount	281,485		302,176
Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	4,620		5,224
ALLL for loans and leases individually evaluated for impairment	82		68
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,294		592
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,509		3,959
Financing Receivable, Individually Evaluated for Impairment	3,803		4,551
Average balance	4,104	2,605
Interest income recognized	48	33
Provision for Loan, Lease, and Other Losses	107	(83)
Financing Receivable, Allowance for Credit Losses, Write-downs	182	0
Recoveries	26	0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	3,831		3,894
Financing Receivable, Collectively Evaluated for Impairment	239,311		243,738
Loans and Leases Receivable, Net Amount	243,114		248,289
Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	44,065		39,946
ALLL for loans and leases individually evaluated for impairment	2,905		2,733
Impaired Financing Receivable, with Related Allowance, Recorded Investment	23,417		19,135
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	17,930		18,707
Financing Receivable, Individually Evaluated for Impairment	41,347		37,842
Average balance	38,724	32,963
Interest income recognized	275	253
Provision for Loan, Lease, and Other Losses	1,512	1,351
Financing Receivable, Allowance for Credit Losses, Write-downs	806	250
Recoveries	77	287
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	13,584		12,973
Financing Receivable, Collectively Evaluated for Impairment	3,546,444		3,485,944
Loans and Leases Receivable, Net Amount	3,587,791		3,523,786
Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	27,948		25,941
ALLL for loans and leases individually evaluated for impairment	1,053		1,085
Impaired Financing Receivable, with Related Allowance, Recorded Investment	9,998		5,875
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	15,527		17,895
Financing Receivable, Individually Evaluated for Impairment	25,525		23,770
Average balance	24,792	7,969
Interest income recognized	201	57
Provision for Loan, Lease, and Other Losses	466	550
Financing Receivable, Allowance for Credit Losses, Write-downs	992	825
Recoveries	194	552
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	21,051		21,351
Financing Receivable, Collectively Evaluated for Impairment	2,626,123		2,677,755
Loans and Leases Receivable, Net Amount	2,651,648		2,701,525
Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	2,872		3,043
ALLL for loans and leases individually evaluated for impairment	713		738
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,744		2,107
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	847		667
Financing Receivable, Individually Evaluated for Impairment	2,591		2,774
Average balance	2,508	1,900
Interest income recognized	28	23
Provision for Loan, Lease, and Other Losses	2,923	1,728
Financing Receivable, Allowance for Credit Losses, Write-downs	5,255	3,966
Recoveries	1,309	$ 1,080
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	29,468		30,466
Financing Receivable, Collectively Evaluated for Impairment	1,551,434		1,558,399
Loans and Leases Receivable, Net Amount	$ 1,554,025		$ 1,561,173

Allowance for Loan and Lease 53

Allowance for Loan and Lease Losses (Troubled Debt Restructuring) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)loans	Mar. 31, 2017USD ($)loans	Dec. 31, 2017USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 163,470		$ 164,561
Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	118	99
Financing Receivable, Modifications, Recorded Investment	$ 144,840		146,126
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 8,778	$ 6,434
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	72	42
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 3,664	$ 4,207
PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	2
Financing Receivable, Modifications, Recorded Investment	$ 18,630		18,435
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 2,271	$ 181
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1,627	$ 73
Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	87,067		95,392
Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,201		4,572
Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	74,408		78,221
Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,441		1,800
Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	8,049		8,508
Commercial | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,968		1,770
Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	0		521
Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	76,403		69,169
Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	3,097		0
Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	46,083		43,542
Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	24,631		22,853
Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,592		2,774
Accruing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	131,920		130,391
Accruing | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	113,540		112,228
Accruing | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	18,380		18,163
Accruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	71,244		76,300
Accruing | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	948		4,089
Accruing | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	61,444		62,358
Accruing | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	950		1,012
Accruing | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	7,000		7,598
Accruing | Commercial | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	902		722
Accruing | Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	0		521
Accruing | Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	60,676		54,091
Accruing | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,914		0
Accruing | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	36,432		34,067
Accruing | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	19,267		17,673
Accruing | Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,063		2,351
Nonaccruing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	31,550		34,170
Nonaccruing | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	31,300		33,898
Nonaccruing | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	250		272
Nonaccruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	15,823		19,092
Nonaccruing | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	253		483
Nonaccruing | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	12,964		15,863
Nonaccruing | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	491		788
Nonaccruing | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,049		910
Nonaccruing | Commercial | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,066		1,048
Nonaccruing | Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	0		0
Nonaccruing | Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	15,727		15,078
Nonaccruing | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	183		0
Nonaccruing | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	9,651		9,475
Nonaccruing | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	5,364		5,180
Nonaccruing | Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 529		$ 423
Interest only period provided | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 644	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Interest only period provided | Commercial | Commercial and industrial | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 644	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Loan term extension | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	6	5
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 932	$ 140
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	1	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 305	$ 577
Loan term extension | Commercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 305	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 305	$ 0
Loan term extension | Commercial | Other commercial real estate | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 530
Loan term extension | Commercial | Commercial and industrial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 549	$ 94
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Loan term extension | Noncommercial | Consumer | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 21	$ 14
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Loan term extension | Noncommercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 32
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 47
Loan term extension | Noncommercial | Revolving mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 57	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Below market interest rate | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	66	53
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 5,660	$ 5,635
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	30	19
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1,814	$ 1,685
Below market interest rate | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 181
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 73
Below market interest rate | Commercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 60
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Below market interest rate | Commercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	6	10
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,380	$ 2,512
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 47	$ 92
Below market interest rate | Commercial | Other commercial real estate | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 4
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Below market interest rate | Commercial | Commercial and industrial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	8	3
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 361	$ 108
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 11	$ 0
Below market interest rate | Commercial | Lease financing | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	3
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 839
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 769
Below market interest rate | Noncommercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 412
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Below market interest rate | Noncommercial | Consumer | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	5	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 71	$ 14
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	3	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 48	$ 0
Below market interest rate | Noncommercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	22	30
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 2,189	$ 1,543
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	10	15
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1,277	$ 824
Below market interest rate | Noncommercial | Mortgage | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 181
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 73
Below market interest rate | Noncommercial | Other | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 143
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Below market interest rate | Noncommercial | Revolving mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	25	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,659	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	11	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 431	$ 0
Discharged from bankruptcy | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	46	41
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 2,186	$ 659
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	41	21
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1,545	$ 1,945
Discharged from bankruptcy | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,627	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1,627	$ 0
Discharged from bankruptcy | Commercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 140	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 502	$ 190
Discharged from bankruptcy | Commercial | Commercial and industrial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	14	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 474	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	16	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 177	$ 0
Discharged from bankruptcy | Commercial | Lease financing | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	5	16
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 304	$ 227
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 73	$ 0
Discharged from bankruptcy | Noncommercial | Consumer | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	13	18
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 262	$ 193
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	11	10
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 183	$ 128
Discharged from bankruptcy | Noncommercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	8	3
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 566	$ 140
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	6	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 417	$ 978
Discharged from bankruptcy | Noncommercial | Mortgage | PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,627	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1,627	$ 0
Discharged from bankruptcy | Noncommercial | Revolving mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	5	4
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 440	$ 99
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	9
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 193	$ 649

Allowance for Loan and Lease 54

Allowance for Loan and Lease Losses (Note Restructurings During Period) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)loans	Mar. 31, 2017USD ($)loans
Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	118	99
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 8,778	$ 6,434
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	72	42
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 3,664	$ 4,207
Non-PCI Loans | Loan term extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	6	5
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 932	$ 140
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	1	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 305	$ 577
Non-PCI Loans | Loan term extension | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 305	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 305	$ 0
Non-PCI Loans | Loan term extension | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 530
Non-PCI Loans | Loan term extension | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 549	$ 94
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Loan term extension | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 32
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 47
Non-PCI Loans | Loan term extension | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 57	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Loan term extension | Noncommercial | Consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 21	$ 14
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Below market interest rate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	66	53
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 5,660	$ 5,635
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	30	19
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 1,814	$ 1,685
Non-PCI Loans | Below market interest rate | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 60
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Below market interest rate | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	6	10
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 1,380	$ 2,512
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 47	$ 92
Non-PCI Loans | Below market interest rate | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 4
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Below market interest rate | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	8	3
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 361	$ 108
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 11	$ 0
Non-PCI Loans | Below market interest rate | Commercial | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	3
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 839
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 769
Non-PCI Loans | Below market interest rate | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 412
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Below market interest rate | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	22	30
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 2,189	$ 1,543
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	10	15
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 1,277	$ 824
Non-PCI Loans | Below market interest rate | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	25	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 1,659	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	11	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 431	$ 0
Non-PCI Loans | Below market interest rate | Noncommercial | Consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	5	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 71	$ 14
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	3	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 48	$ 0
Non-PCI Loans | Below market interest rate | Noncommercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 143
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
Non-PCI Loans | Discharged from bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	46	41
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 2,186	$ 659
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	41	21
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 1,545	$ 1,945
Non-PCI Loans | Discharged from bankruptcy | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 140	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 502	$ 190
Non-PCI Loans | Discharged from bankruptcy | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	14	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 474	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	16	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 177	$ 0
Non-PCI Loans | Discharged from bankruptcy | Commercial | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	5	16
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 304	$ 227
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 73	$ 0
Non-PCI Loans | Discharged from bankruptcy | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	8	3
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 566	$ 140
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	6	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 417	$ 978
Non-PCI Loans | Discharged from bankruptcy | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	5	4
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 440	$ 99
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	9
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 193	$ 649
Non-PCI Loans | Discharged from bankruptcy | Noncommercial | Consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	13	18
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 262	$ 193
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	11	10
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 183	$ 128
PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 2,271	$ 181
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 1,627	$ 73
PCI Loans | Interest only period provided
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 644	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
PCI Loans | Interest only period provided | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 644	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 0
PCI Loans | Below market interest rate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 181
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 73
PCI Loans | Below market interest rate | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 0	$ 181
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 0	$ 73
PCI Loans | Discharged from bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 1,627	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 1,627	$ 0
PCI Loans | Discharged from bankruptcy | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Post-Modification Recorded Investment | $	$ 1,627	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment | $	$ 1,627	$ 0

Other Real Estate Owned (Detail

Other Real Estate Owned (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Real Estate Properties [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	$ 30,600		$ 26,900
Total
Beginning balance	51,097	$ 61,231
Additions	6,582	5,822
Sales	(8,380)	(8,845)
Write-downs	(1,210)	(1,717)
Ending balance	48,089	$ 56,491
Mortgage
Total
Beginning balance	19,800
Ending balance	$ 16,500

FDIC Shared-Loss Receivable (Ch

FDIC Shared-Loss Receivable (Changes in Receivable from FDIC) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Receivable From FDIC For Shared-Loss Agreements [Roll Forward]
Accretion of discounts and premiums, net	$ (421)	$ (600)
Receipt of payments from FDIC	0	2,760
Post-acquisition and other adjustments, net	1,834	(2,591)
Termination of FDIC shared-loss agreements	0	240
FDIC shared-loss receivable	$ 3,636	$ 3,981	$ 2,223	$ 4,172

FDIC Shared-Loss Receivable FDI

FDIC Shared-Loss Receivable FDIC Shared-Loss Payable (Changes in Payable to FDIC) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
FDIC Shared-Payable [Abstract]
FDIC shared-loss payable	$ 102,466	$ 98,013	$ 101,342	$ 97,008
Accretion expense	992	954
Adjustments related to changes in assumptions	$ 132	$ 51

FDIC Shared-Loss Receivable (Na

FDIC Shared-Loss Receivable (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
FDIC Shared-Loss Receivable [Abstract]
Net payment to the FDIC for termination of shared-loss agreements	$ 0	$ 285
Termination of FDIC shared-loss agreements	0	240
Loss on termination of FDIC share-loss agreements	0	(45)
FDIC shared-loss payable	102,466	98,013	$ 101,342	$ 97,008
Net Impact from FDIC shared-loss termination	0	$ (45)
Loans and Leases Receivable, Gross, Carrying Amount, Covered	$ 65,500		$ 67,800

Mortgage Servicing Rights (MSR

Mortgage Servicing Rights (MSR Carrying Value) ((Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Servicing Asset at Amortized Cost [Line Items]
Mortgage servicing rights	$ 21,659	$ 20,771	$ 21,945	$ 20,415
Amortization of Mortgage Servicing Rights (MSRs)	(1,486)	(1,350)
Servicing Asset at Amortized Cost, Additions	1,200	1,702
Valuation allowance (provision) reversal	$ 0	$ 4

Mortgage Servicing Rights (Valu

Mortgage Servicing Rights (Valuation allowance) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Valuation Allowance for Impairment of Recognized Servicing Assets [Line Items]
Valuation allowance provision (reversal)	$ 0	$ (4)

Mortgage Servicing Rights (Econ

Mortgage Servicing Rights (Economic Assumptions) (Details) - $ / loans	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Servicing Asset Key Economic Assumptions [Line Items]
Weighted average constant prepayment rate	9.15%	10.93%
Weighted average cost to service a loan	72.80	64.03
Conventional fixed loans
Servicing Asset Key Economic Assumptions [Line Items]
Discount rate	9.74%	9.41%
All loans excluding conventional fixed loans
Servicing Asset Key Economic Assumptions [Line Items]
Discount rate	10.74%	10.41%

Mortgage Servicing Rights (Narr

Mortgage Servicing Rights (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Mortgage Servicing Rights [Abstract]
Residential Mortgage Loans Serviced	$ 2,850,000		$ 2,810,000
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	1,900	$ 1,700
Amortization of Mortgage Servicing Rights (MSRs)	1,486	1,350
Valuation allowance provision (reversal)	$ 0	$ (4)

Repurchase Agreements (Details)

Repurchase Agreements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	$ 535,600	$ 684,200
Securities Sold under Agreements to Repurchase, Gross	522,207	586,171
U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	522,207	586,171
Overnight and continuous | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	522,207	556,171
Up to 30 days | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	0
30 - 90 days | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	30,000
Greater than 90 days | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	$ 0	$ 0

Estimated Fair Values (Estimate

Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 248,139	$ 336,150
Overnight investments	1,946,882	1,387,927
Investment securities available for sale	6,857,740	7,180,180
Investment securities held to maturity	74	76
Marketable equity securities	110,107	0
Loans held for sale	46,660	51,179
Loans and Leases Receivable, Net Amount	23,388,861	23,374,932
FDIC shared-loss receivable	3,636	2,223	$ 3,981	$ 4,172
Income earned not collected	96,607	95,249
Mortgage servicing rights	21,659	21,945	20,771	20,415
Deposits	29,969,245	29,266,275
FDIC shared-loss payable	102,466	101,342	$ 98,013	$ 97,008
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	248,139	336,150
Overnight investments	1,946,882	1,387,927
Investment securities available for sale	6,857,740	7,180,180
Investment securities held to maturity	74	76
Marketable equity securities	110,107	0
Loans held for sale	46,660	51,179
Loans and Leases Receivable, Net Amount	23,388,861	23,374,932
FDIC shared-loss receivable	3,636	2,223
Income earned not collected	96,607	95,249
Stock issued by Federal Home Loan Bank	20,810	52,685
Mortgage servicing rights	21,659	21,945
Deposits	29,969,245	29,266,275
Short-term borrowings	554,758	693,807
Long-term obligations	194,413	870,240
FDIC shared-loss payable	102,466	101,342
Accrued interest payable	1,498	3,952
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	248,139	336,150
Overnight investments	1,946,882	1,387,927
Investment securities available for sale	6,857,740	7,180,180
Investment securities held to maturity	79	81
Marketable equity securities	110,107	0
Loans held for sale	46,660	51,179
Loans and Leases Receivable, Net Amount	22,672,287	22,257,803
FDIC shared-loss receivable	3,636	2,223
Income earned not collected	96,607	95,249
Stock issued by Federal Home Loan Bank	20,810	52,685
Mortgage servicing rights	27,512	26,170
Deposits	29,924,950	29,230,768
Short-term borrowings	554,758	693,807
Long-term obligations	203,061	852,112
FDIC shared-loss payable	103,440	102,684
Accrued interest payable	$ 1,498	$ 3,952

Estimated Fair Values (Narrativ

Estimated Fair Values (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 6,857,740		$ 7,180,180
Asset transfers between Level 1 and Level 2	0
Liability transfers between Level 2 and Level 1	0
Asset transfers between Level 2 and Level 1	0
Gains (Losses) from fair value changes on originated loans held for sale	(455)	$ 3,161
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at fair value on nonrecurring basis	$ 0		$ 0
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discounts for collateral value estimates due to estimated holding and selling costs (percent)	6.00%		6.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discounts for collateral value estimates due to estimated holding and selling costs (percent)	11.00%		11.00%
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	$ 59,700
Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	$ 5,600

Estimated Fair Values (Assets A

Estimated Fair Values (Assets And Liabilities Carried At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 6,857,740	$ 7,180,180
Marketable equity securities	110,107	0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	6,857,740
Marketable equity securities	110,107
Loans held for sale	46,660	51,179
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	19,341
Marketable equity securities	21,749
Loans held for sale	0	0
Fair Value, Measurements, Recurring | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	6,792,469
Marketable equity securities	88,358
Loans held for sale	46,660	51,179
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	65,271	0
Marketable equity securities	0
Loans held for sale	0	0
Fair Value, Measurements, Recurring | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	1,553,893	1,657,864
Fair Value, Measurements, Recurring | U.S. Treasury | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | U.S. Treasury | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	1,553,893	1,657,864
Fair Value, Measurements, Recurring | U.S. Treasury | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Government Agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	31,909	8,670
Fair Value, Measurements, Recurring | Government Agency | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Government Agency | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	31,909	8,670
Fair Value, Measurements, Recurring | Government Agency | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Mortgage Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,206,667	5,340,756
Fair Value, Measurements, Recurring | Mortgage Backed Securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Mortgage Backed Securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,206,667	5,340,756
Fair Value, Measurements, Recurring | Mortgage Backed Securities | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,618	7,719
Fair Value, Measurements, Recurring | Other | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Other | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	7,719
Fair Value, Measurements, Recurring | Other | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,618	0
Fair Value, Measurements, Recurring | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	59,653	59,963
Fair Value, Measurements, Recurring | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring | Corporate Bonds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0	59,963
Fair Value, Measurements, Recurring | Corporate Bonds | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 59,653	$ 0

Estimated Fair Values (Assets67

Estimated Fair Values (Assets And Liabilities Carried At Fair Value On A Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate remeasured during current year	$ 48,089	$ 51,097	$ 56,491	$ 61,231
Mortgage servicing rights	21,659	21,945	$ 20,771	$ 20,415
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	73,892	72,539
Other real estate remeasured during current year	11,695	40,167
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate remeasured during current year	0	0
Fair Value, Measurements, Nonrecurring | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate remeasured during current year	0	0
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	73,892	72,539
Other real estate remeasured during current year	$ 11,695	$ 40,167

Estimated Fair Values (Fair Val

Estimated Fair Values (Fair Value Option) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Gains (Losses) from fair value changes on originated loans held for sale	$ (455)	$ 3,161
Loans Held For Sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of originated loans held for sale	46,660		$ 51,179
Aggregate unpaid principle balance of originated loans held for sale	45,732		49,796
Difference between fair value and aggregate unpaid principle balance of originated loans held for sale	$ 928		$ 1,383

Employee Benefit Plans (Compone

Employee Benefit Plans (Components Of Pension Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
BancShares Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 3,429	$ 3,376
Interest cost	7,057	7,380
Expected return on assets	(11,957)	(10,698)
Amortization of prior service cost	20	52
Amortization of net actuarial loss	3,246	2,234
Total pension expense	1,795	2,344
Bancorporation Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	662	671
Interest cost	1,587	1,683
Expected return on assets	(3,106)	(2,796)
Amortization of net actuarial loss	71	214
Total pension expense	$ (786)	$ (228)

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions in current year	$ 50
BancShares Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	0
Bancorporation Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0

Commitments and Contingencies71

Commitments and Contingencies (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)Advances	Dec. 31, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Guarantor Obligations [Line Items]
Qualified Affordable Housing Project Investments	$ 134,400	$ 128,004
FDIC shared-loss receivable	3,636	2,223	$ 3,981	$ 4,172
FDIC shared-loss payable	$ 102,466	101,342	$ 98,013	$ 97,008
Number Of Federal Home Loan Bank Advances | Advances
Commitments to Extend Credit
Guarantor Obligations [Line Items]
Unused Commitments to Extend Credit	$ 9,994,802	9,629,365
Qualified Affordable Housing Project Investments, Commitment	63,803	61,819
Standby Letters of Credit
Guarantor Obligations [Line Items]
Guarantor obligations amount	$ 81,059	81,530
Recourse Obligation on Mortgage Loans Sold
Guarantor Obligations [Line Items]
Recourse Period, Maximum1	180 days
Obligation to Repurchase Receivables Sold
Guarantor Obligations [Line Items]
Reserve for estimated losses arising from repurchase of loans	$ 900	$ 900

Accumulated Other Comprehensi72

Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), before Tax		$ (299,122)		$ (193,833)
Deferred tax expense (benefit)		(68,799)		(71,539)
Accumulated other comprehensive income (loss), net of tax		(230,323)	$ (110,941)	(122,294)	$ (135,192)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(2,569)	(1,574)
Amortization of actuarial losses and prior service cost		(3,317)	(2,448)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax		3,337	2,500
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), before Tax		(157,460)		(48,834)
Deferred tax expense (benefit)		(36,217)		(17,889)
Accumulated other comprehensive income (loss), net of tax	[1]	(121,243)	(23,183)	(30,945)	(45,875)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	0	(15)
Funded Status of Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), before Tax		(141,662)		(144,999)
Deferred tax expense (benefit)		(32,582)		(53,650)
Accumulated other comprehensive income (loss), net of tax	[1]	(109,080)	(87,758)	$ (91,349)	$ (89,317)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	$ (2,569)	$ (1,559)
[1]	All amounts are net of tax.

Accumulated Other Comprehensi73

Accumulated Other Comprehensive Income (Loss) (Components of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (122,294)	$ (135,192)
Other comprehensive income before reclassifications		(60,546)	22,677
Amounts reclassified from accumulated other comprehensive (loss) income		2,569	1,574
Net current period other comprehensive income		(57,977)	24,251
Ending balance		(230,323)	(110,941)
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(30,945)	(45,875)
Other comprehensive income before reclassifications	[1]	(60,546)	22,677
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	0	15
Net current period other comprehensive income	[1]	(60,546)	22,692
Ending balance	[1]	(121,243)	(23,183)
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(91,349)	(89,317)
Other comprehensive income before reclassifications	[1]	0	0
Amounts reclassified from accumulated other comprehensive (loss) income	[1]	2,569	1,559
Net current period other comprehensive income	[1]	2,569	1,559
Ending balance	[1]	$ (109,080)	$ (87,758)
[1]	All amounts are net of tax.

Accumulated Other Comprehensi74

Accumulated Other Comprehensive Income (Loss) (Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains and losses on available for sale securities reclassified from AOCI before tax		$ 0	$ (24)
Amortization of actuarial losses and prior service cost		(3,317)	(2,448)
Total before taxes		(3,337)	(2,500)
Amounts reclassified from accumulated other comprehensive income, net of tax		2,569	1,574
Unrealized gains and losses on available for sale securities reclassified from AOCI tax		0	9
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax			(15)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax		(20)	(52)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax		768	941
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax		(2,569)	(1,559)
Unrealized Gains on Investment Securities Available for Sale
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income, net of tax	[1]	0	15
Defined Benefit Pension Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income, net of tax	[1]	$ 2,569	$ 1,559
[1]	All amounts are net of tax.