First Citizens BancShares (FCNCO) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2015	6-May-15
Entity Registrant Name	FIRST CITIZENS BANCSHARES INC /DE/
Entity Central Index Key	798941
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
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 $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets
Cash and due from banks	$495,901	$604,182
Overnight investments	2,458,923	1,724,919
Investment securities available for sale	7,045,109	7,171,917
Investment securities held to maturity	441	518
Loans held for sale	66,508	63,696
Less allowance for loan and lease losses	-205,553	-204,466
Net loans and leases	18,886,204	18,564,999
Loans and Leases Receivable, Gross	19,091,757	18,769,465
Premises and equipment	1,116,293	1,125,081
Other real estate owned:
Other Real Estate, Covered	17,302	22,982
Other Real Estate, Non Covered	72,690	70,454
Income earned not collected	63,165	57,254
FDIC Indemnification Asset	21,340	28,701
Goodwill	139,773	139,773
Other intangible assets	101,904	106,610
Other assets	368,096	394,027
Total assets	30,853,649	30,075,113
Liabilities
Noninterest-bearing	8,484,192	8,086,784
Interest-bearing	17,816,638	17,591,793
Total deposits	26,300,830	25,678,577
Short-term borrowings	941,850	987,184
Long-term obligations	468,180	351,320
FDIC loss share payable	118,645	116,535
Other liabilities	258,767	253,903
Total liabilities	28,088,272	27,387,519
Shareholders' Equity
Surplus	658,918	658,918
Retained earnings	2,129,860	2,069,647
Accumulated other comprehensive loss	-35,411	-52,981
Total shareholders' equity	2,765,377	2,687,594
Total liabilities and shareholders' equity	30,853,649	30,075,113
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 $)	Mar. 31, 2015	Dec. 31, 2014
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

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest income
Loans and leases	$210,862	$161,034
Investment securities:
Total investment securities interest and dividend income	19,310	11,748
Overnight investments	1,338	612
Total interest income	231,510	173,394
Interest expense
Deposits	5,629	6,825
Short-term borrowings	1,934	585
Long-term obligations	3,782	5,053
Total interest expense	11,345	12,463
Net interest income	220,165	160,931
Provision (credit) for loan and lease losses	5,792	-1,903
Net interest income after provision for loan and lease losses	214,373	162,834
Noninterest income
Gain on acquisition	37,555	0
Cardholder services	18,401	11,832
Merchant services	18,880	13,521
Service charges on deposit accounts	22,058	14,440
Wealth management services	20,880	14,880
Fees and Commissions, Correspondent Clearing	50	4,861
Securities gains (losses)	5,126	0
Other service charges and fees	5,455	3,944
Mortgage income	4,549	955
Insurance commissions	3,297	3,287
ATM income	1,664	1,202
Adjustments for FDIC receivable for loss share agreements	-1,047	-12,349
Other	8,510	5,741
Total noninterest income	145,378	62,314
Noninterest expense
Salaries and wages	106,543	79,353
Employee benefits	30,146	20,100
Occupancy expense	25,620	20,410
Equipment expense	23,541	18,773
FDIC insurance expense	4,271	2,636
Foreclosure-related expenses	2,557	5,410
Merger-related expenses	2,997	2,453
Other	62,585	41,895
Total noninterest expense	258,260	191,030
Income before income taxes	101,491	34,118
Income taxes	37,675	11,639
Net income	$63,816	$22,479
Average shares outstanding (in shares)	12,010,405	9,618,941
Net income per share	$5.31	$2.34

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$63,816	$22,479
Unrealized gains and losses on securities:
Change in unrealized securities gains (losses) arising during period	30,415	11,899
Tax effect	-11,813	-4,643
Reclassification adjustment for gains included in income before income taxes	5,126	0
Tax effect	1,977	0
Total change in unrealized gains and losses on securities, net of tax	15,453	7,256
Change in fair value of cash flow hedges:
Change in unrecognized loss on cash flow hedges	576	719
Tax effect	-222	-278
Total change in unrecognized loss on cash flow hedges, net of tax	354	441
Change in pension obligation:
Reclassification adjustment for losses included in income before income taxes	2,886	1,599
Tax effect	-1,123	-622
Total change in pension obligation, net of tax	1,763	977
Net current period other comprehensive income	17,570	8,674
Total comprehensive income	$81,386	$31,153

Consolidated_Statements_of_Cha

Consolidated Statements of Changes In Shareholders' Equity (USD $)	Total	Common Stock	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Loss
In Thousands, unless otherwise specified		Class A Common Stock	Class B Common Stock
Beginning balance at Dec. 31, 2013	$2,071,462	$8,586	$1,033	$143,766	$1,943,345	($25,268)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	22,479	0	0	0	22,479	0
Net current period other comprehensive income	8,674	0	0	0	0	8,674
Cash dividends	-2,885	0	0	0	-2,885	0
Ending balance at Mar. 31, 2014	2,099,730	8,586	1,033	143,766	1,962,939	-16,594
Beginning balance at Dec. 31, 2014	2,687,594	11,005	1,005	658,918	2,069,647	-52,981
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,816	0	0	0		0
Net current period other comprehensive income	17,570	0	0	0	0
Cash dividends	-3,603	0	0	0	-3,603	0
Ending balance at Mar. 31, 2015	$2,765,377	$11,005	$1,005	$658,918	$2,129,860	($35,411)

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes In Shareholders' Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)		0.3
Class A Common Stock
Statement of Stockholders' Equity [Abstract]
Repurchase of common stock (in shares)	0	0
Class B Common Stock
Statement of Stockholders' Equity [Abstract]
Repurchase of common stock (in shares)	0	0

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
OPERATING ACTIVITIES
Net income	$63,816	$22,479
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	5,792	-1,903
Deferred tax expense (benefit)	-10,203	-4,960
Net change in current taxes	13,310	40,710
Depreciation	21,965	17,684
Increase (decrease) in accrued interest payable	176	-1,062
Net (increase) decrease in income earned not collected	-5,911	-1,278
Gain on acquisition	37,555	0
Securities (gains) losses	-5,126	0
Origination of loans held for sale	-126,547	-67,862
Proceeds from sale of loans held for sale	127,203	64,009
Gain on sale of loans	-3,468	-1,054
Net writedowns/losses on other real estate	1,978	3,441
Net amortization of premiums and discounts	-17,150	-5,413
Amortization of intangible assets	5,206	637
FDIC receivable for loss share agreements	8,092	4,359
FDIC payable for loss share agreements	2,110	1,961
Net change in other assets	19,380	-8,891
Net change in other liabilities	-336	225
Net cash provided by operating activities	62,732	63,082
INVESTING ACTIVITIES
Net change in loans outstanding	-168,341	-4,788
Purchases of investment securities available for sale	-626,268	-911,409
Proceeds from maturities of investment securities held to maturity	77	125
Proceeds from maturities of investment securities available for sale	330,500	866,803
Proceeds from sales of investment securities available for sale	481,708	0
Net change in overnight investments	-734,004	-302,145
Cash (paid to) received from the FDIC for loss share agreements	-5,762	-3,490
Proceeds from sale of other real estate	22,794	10,602
Additions to premises and equipment	-13,177	-17,326
Business acquisition, net of cash acquired	123,137	18,194
Net cash (used) provided by investing activities	-589,336	-343,434
FINANCING ACTIVITIES
Net change in time deposits	-189,906	-51,268
Net change in demand and other interest-bearing deposits	545,807	308,876
Net change in short-term borrowings	-50,835	35,970
Repayment of long-term obligations	-3,140	-469
Origination of long-term obligations	120,000	0
Cash dividends paid	-3,603	-2,885
Net cash provided (used) by financing activities	418,323	290,224
Change in cash and due from banks	-108,281	9,872
Cash and due from banks at beginning of period	604,182	533,599
Cash and due from banks at end of period	495,901	543,471
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	21,300	4,832
Dividends Declared but not Paid	$3,603	$2,885

Accounting_Policies_and_Basis_

Accounting Policies and Basis of Presentation	3 Months Ended
	Mar. 31, 2015
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 footnotes included in BancShares' Annual Report on Form 10-K for the year ended December 31, 2014.
	Reclassifications
	Prior period financial statements reflect the retrospective application of Accounting Standards Update ("ASU") 2014-01, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments Qualified Affordable Housing Projects which was adopted effective in the fourth quarter of 2014 and did not have a material impact on our consolidated financial condition or results of operations. In certain instances other than the retrospective adoption of ASU 2014-01, 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 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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. 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
	•	Receivable from and payable to the FDIC for loss share agreements
	•	Income tax assets, liabilities and expense
	Recently Adopted Accounting Pronouncements
	Financial Accounting Standards Board (FASB) ASU 2014-14, Receivables - Troubled Debt Restructurings by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure
	This ASU requires a reporting entity to derecognize a mortgage loan and recognize a separate other receivable upon foreclosure if the following conditions are met: the loan has a government guarantee that is not separable from the loan before foreclosure; at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim and at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable should be measured based on the amount of the loan balance expected to be recovered from the guarantor.
	The amendments in this ASU were effective for public entities for annual periods, and interim periods within those annual periods, beginning after December 15, 2014. We adopted this guidance effective in the first quarter of 2015. The initial adoption did not have any effect on our consolidated financial position or consolidated results of operations.
	FASB ASU 2014-11, Transfers and Servicing (Topic 860)
	This ASU aligns the accounting for repurchase-to-maturity transactions and repurchase agreements executed as a repurchase financing with the accounting for other typical repurchase agreements. Going forward, these transactions would all be accounted for as secured borrowings. The guidance eliminates sale accounting for repurchase-to-maturity transactions and supersedes the guidance under which a transfer of a financial asset and a contemporaneous repurchase financing could be accounted for on a combined basis as a forward agreement, which has resulted in outcomes referred to as off-balance-sheet accounting. The ASU requires a new disclosure for transactions economically similar to repurchase agreements in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The ASU also requires expanded disclosures about the nature of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings.
	The accounting changes in this ASU were effective for fiscal years beginning after December 15, 2014. In addition, the disclosure for certain transactions accounted for as a sale was effective for the fiscal period beginning after December 15, 2014, the disclosures for transactions accounted for as secured borrowings were required to be presented for fiscal periods beginning after December 15, 2014, and interim periods beginning after March 15, 2015. We adopted the guidance effective in the first quarter of 2015. The initial adoption did not have any effect on our consolidated financial position or consolidated results of operations. The new disclosures required by this ASU are included in Note I.
	FASB ASU 2014-04, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40)
	This ASU clarifies that an in-substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Additionally, the amendments require interim and annual disclosure of both (1) the amount of foreclosed residential real estate property held by the creditor and (2) the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure according to local requirements of the applicable jurisdiction.
	The amendments in this ASU were effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014. We adopted the guidance effective in the first quarter of 2015. The initial adoption did not have any effect on our consolidated financial position or consolidated results of operations. The new disclosures required by this ASU are included in Note F.
	FASB ASU 2014-01, Investments - Equity Method and Joint Ventures (Topic 323) - Accounting for Investments in Qualified Affordable Housing Projects
	This ASU permits an accounting policy election to account for investments in qualified affordable housing projects (LIHTC) using the proportional amortization method if certain conditions are met. Under the proportional amortization method, the initial cost of the investment is amortized in proportion to the tax credits and other tax benefits received and recognize the net investment performance in the income statement as a component of income tax expense (benefit).
	For those investments in qualified affordable housing projects not accounted for using the proportional amortization method, the investment should be accounted for as an equity method investment or a cost method investment in accordance with ASC 970-323.
	The decision to apply the proportional amortization method of accounting will be applied consistently to all qualifying affordable housing project investments rather than a decision to be applied to individual investments.
	BancShares early adopted the guidance effective in the fourth quarter of 2014. Previously, LIHTC investments were accounted for under the cost or equity method, and the amortization was recorded as a reduction to other noninterest income, with the tax credits and other benefits received recorded as a component of the provision for income taxes. BancShares believes the proportional amortization method better represents the economics of LIHTC investments and provides users with a better understanding of the returns from such investments than the cost or equity method. LIHTC investments were $65.3 million and $57.1 million at March 31, 2015 and December 31, 2014, respectively, included in "other assets" on the Consolidated Balance Sheets.
	The cumulative effect of the retrospective application of the change in amortization method was a $2.4 million decrease to both "other assets" and "retained earnings" on the Consolidated Balance Sheets as of January 1, 2012. Under the new amortization method of accounting, amortization expense is recognized in income tax expense in the Consolidated Statements of Income and is offset by the tax effect of tax losses and tax credits received from the investments. This change resulted in a reclassification of expense previously recorded as a reduction in other noninterest income to income tax expense along with additional amortization recognized under the new method of accounting in the Consolidated Statements of Income. An additional change resulting from the new amortization method of accounting was that a deferred tax asset or liability no longer exists as a result of these investments, thus in the retrospective application of the new method, the removal of the deferred tax asset previously reported as well as the additional amortization of the investments, both recorded in other assets, reflected in the Consolidated Balance Sheets were removed. We do not believe the impact of this change in accounting principle is material.
	Recently Issued Accounting Pronouncements
	FASB ASU 2015-03, Interest–Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs
	This ASU simplifies the presentation of debt issuance costs by requiring that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liability, consistent with debt discounts or premiums. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update.
	This ASU is effective for interim and annual periods beginning after December 15, 2015 for public companies, and is to be applied retrospectively. Early adoption is permitted. We will adopt the guidance effective in the first quarter of 2016.
	FASB ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis
	This ASU improves targeted areas of consolidation guidance for reporting organizations that are required to evaluate whether they should consolidate certain legal entities. In addition to reducing the number of consolidation models from four to two, the new standard places more emphasis on risk of loss when determining a controlling financial interest, reducing the frequency of the application of related-party guidance when determining a controlling financial interest in a variable interest entity ("VIE"), and changing consolidation conclusions for public and private companies in several industries that typically make use of limited partnerships or VIEs.
	The amendments in this ASU are effective for periods beginning after December 15, 2015 for public companies. Early adoption is permitted. We will adopt the guidance effective in the first quarter of 2016 and do not anticipate any significant impact on our consolidated financial position or consolidated results of operations as a result of adoption.
	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 companies 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 also results in enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively and improves guidance for multiple-element arrangements.
	The guidance in this ASU is effective for fiscal periods beginning after December 15, 2016, including interim reporting periods within that reporting period. Early adoption is not permitted. We are currently evaluating the impact of the new standard and we will adopt during the first quarter of 2017 using one of two retrospective application methods.

Business_Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Business Combinations	NOTE B - BUSINESS COMBINATIONS
	Capitol City Bank & Trust Company
	On February 13, 2015, FCB entered into an agreement with the Federal Deposit Insurance Corporation ("FDIC"), as Receiver, to purchase certain assets and assume certain liabilities of Capitol City Bank & Trust Company ("CCBT") of Atlanta, Georgia. The acquisition expanded FCB's presence in Georgia as Capitol City Bank & Trust Company operated eight branch locations in Atlanta, Stone Mountain, Albany, Augusta and Savannah, Georgia.
	The fair value of the assets acquired recorded was $206.6 million, including $149.3 million in loans and $500 thousand of identifiable intangible assets. Liabilities assumed were $272.5 million of which $266.4 million were deposits. As a result of the transaction, FCB recorded a gain on the acquisition of $37.6 million which is included in noninterest income on the Consolidated Statements of Income.
	The CCBT transaction was accounted for under the acquisition method of accounting and, accordingly, assets acquired and liabilities assumed were recorded at their estimated fair values on the acquisition date. Fair values are preliminary and subject to refinement for up to one year after the closing date of the acquisition as additional information regarding closing date fair values becomes available.
	The following table provides the identifiable assets acquired and liabilities assumed at their estimated fair values as of the acquisition date.
	(Dollars in thousands)		As recorded by FCB
	Assets
	Cash and cash equivalents		$	19,622
	Investment securities		35,413
	Loans		149,294
	Intangible assets		500
	Other assets		1,731
	Total assets acquired		206,560
	Liabilities
	Deposits		266,352
	Short-term borrowings		5,501
	Other liabilities		667
	Total liabilities assumed		272,520
	Fair value of net liabilities assumed		(65,960		)
	Cash received from FDIC		103,515
	Gain on acquisition of CCBT		$	37,555
	Merger-related expenses of $213 thousand were recorded in the Consolidated Statement of Income for the first quarter of 2015. Loan-related interest income generated from the CCBT was approximately $1.3 million since the acquisition date.
	All loans resulting from the CCBT transaction were recognized upon acquisition date with a discount attributable, at least in part, to credit quality, and are therefore accounted for as purchased credit-impaired (PCI) loans under ASC 310-30.
	First Citizens Bancorporation, Inc. and First Citizens Bank and Trust Company, Inc.
	On October 1, 2014, BancShares completed the merger of First Citizens Bancorporation, Inc. ("Bancorporation") with and into BancShares pursuant to an Agreement and Plan of Merger dated June 10, 2014, as amended on July 29, 2014. First Citizens Bank and Trust Company, Inc. merged with and into FCB on January 1, 2015.
	Under the terms of the Merger Agreement, each share of Bancorporation common stock was converted into the right to receive 4.00 shares of BancShares' Class A common stock and $50.00 cash, unless the holder elected for each share to be converted into the right to receive 3.58 shares of BancShares' Class A common stock and 0.42 shares of BancShares' Class B common stock. BancShares issued 2,586,762 Class A common shares at a fair value of $560.4 million and 18,202 Class B common shares at a fair value of $3.9 million to Bancorporation shareholders. Also, cash paid to Bancorporation shareholders was $30.4 million. At the time of the merger, Bancorporation owned 32,042 shares of common stock in Bancorporation with an approximate fair value of $29.6 million. The fair value of common stock owned by BancShares in Bancorporation was considered part of the purchase price, and the shares ceased to exist after completion of the merger.
	The Bancorporation transaction was accounted for under the acquisition method of accounting and, accordingly, assets acquired and liabilities assumed were recorded at their estimated fair values on the acquisition date. Fair values are preliminary and subject to refinement for up to one year after the closing date of the acquisition. Assets acquired, excluding goodwill, totaled $8.28 billion, including $4.49 billion in loans and leases, $2.01 billion of investment securities available for sale, $1.28 billion in cash and overnight investments, and $109.4 million of identifiable intangible assets. Liabilities assumed were $7.66 billion, including $7.17 billion of deposits. Goodwill of $4.2 million was recorded as result of the excess purchase price over the estimated fair value of the net assets acquired.
	The following unaudited pro forma financial information reflects the consolidated results of operations of BancShares. These results combine the historical results of Bancorporation in the BancShares' Consolidated Statements of Income and, while certain adjustments were made for the estimated impact of certain fair value adjustments and other acquisition-related activity, they are not indicative of what would have occurred had the acquisition taken place at the beginning of the period presented. The unaudited pro forma information has been presented for illustrative purposes only and is not necessarily indicative of the consolidated results of operations that would have been achieved or the future results of operations of BancShares.
		Three months ended March 31
	(Dollars in thousands)	2014
	Total revenue (interest income plus noninterest income)	$	323,524
	Net income	$	37,230

Investments

Investments	3 Months Ended
	Mar. 31, 2015
Investments [Abstract]
Investments	INVESTMENTS
	The amortized cost and fair value of investment securities classified as available for sale and held to maturity at March 31, 2015 and December 31, 2014, are as follows:
		March 31, 2015
	(Dollars in thousands)	Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	Investment securities available for sale
	U.S. Treasury	$	2,237,002		$	9,966	$	2	$	2,246,966
	Government agency	988,563			2,382		51		990,894
	Mortgage-backed securities	3,785,912			27,006		5,669		3,807,249
	Total investment securities available for sale	$	7,011,477		$	39,354	$	5,722	$	7,045,109
		December 31, 2014
		Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	U.S. Treasury	$	2,626,900		$	2,922	$	152	$	2,629,670
	Government agency	908,362			702		247		908,817
	Mortgage-backed securities	3,628,187			16,964		11,847		3,633,304
	Municipal securities	125			1		—		126
	Total investment securities available for sale	$	7,163,574		$	20,589	$	12,246	$	7,171,917
		March 31, 2015
		Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	Investment securities held to maturity
	Mortgage-backed securities	$	441		$	18	$	—	$	459
		December 31, 2014
		Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	Mortgage-backed securities	$	518		$	26	$	—	$	544
	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.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, 2015					December 31, 2014
	(Dollars in thousands)	Cost			Fair		Cost		Fair
					value				value
	Investment securities available for sale
	Non-amortizing securities maturing in:
	One year or less	$	504,826		$	505,182	$	447,866	$	447,992
	One through five years	2,720,739			2,732,678		3,087,521		3,090,621
	Mortgage-backed securities	3,785,912			3,807,249		3,628,187		3,633,304
	Total investment securities available for sale	$	7,011,477		$	7,045,109	$	7,163,574	$	7,171,917
	Investment securities held to maturity
	Mortgage-backed securities held to maturity	$	441		$	459	$	518	$	544
	For each period presented, securities gains (losses) included the following:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Gross gains on sales of investment securities available for sale	$	5,135		$	—
	Gross losses on sales of investment securities available for sale	(9		)	—
	Total securities gains	$	5,126		$	—
	The following table provides information regarding securities with unrealized losses as of March 31, 2015 and December 31, 2014.
		March 31, 2015
		Less than 12 months					12 months or more				Total
	(Dollars in thousands)	Fair			Unrealized		Fair		Unrealized		Fair		Unrealized
		value			losses		value		losses		value		losses
	Investment securities available for sale:
	U.S. Treasury	$	13,024		$	2	$	—	$	—	$	13,024	$	2
	Government agency	69,660			51		—		—		69,660		51
	Mortgage-backed securities	562,616			1,645		317,685		4,024		880,301		5,669
	Total	$	645,300		$	1,698	$	317,685	$	4,024	$	962,985	$	5,722
		December 31, 2014
		Less than 12 months					12 months or more				Total
		Fair			Unrealized		Fair		Unrealized		Fair		Unrealized
		value			losses		value		losses		value		losses
	Investment securities available for sale:
U.S. Treasury	$	338,612		$	151	$	1,015	$	1	$	339,627	$	152
Government agency	261,288			247		—		—		261,288		247
Mortgage-backed securities	573,374			1,805		831,405		10,042		1,404,779		11,847
Total	$	1,173,274		$	2,203	$	832,420	$	10,043	$	2,005,694	$	12,246
Investment securities with an aggregate fair value of $317.7 million and $832.4 million had continuous unrealized losses for more than 12 months as of March 31, 2015 and December 31, 2014, with an aggregate unrealized loss of $4.0 million and $10.0 million, respectively. As of March 31, 2015, all 38 of these investments are government sponsored enterprise-issued mortgage-backed securities. None of the unrealized losses identified as of March 31, 2015 or December 31, 2014 relate to the marketability of the securities or the issuer’s ability to honor redemption obligations. 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.
Investment securities having an aggregate carrying value of $4.45 billion at March 31, 2015 and $4.37 billion at December 31, 2014 were pledged as collateral to secure public funds on deposit and certain short-term borrowings, and for other purposes as required by law.

Loans_and_Leases

Loans and Leases	3 Months Ended
	Mar. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	LOANS AND LEASES
	Loans and leases are evaluated at acquisition and where a discount is required at least in part due to credit quality, the nonrevolving loans are accounted for under the guidance in ASC Topic 310-30, Loans and Debt Securities Acquired with
	Deteriorated Credit Quality. Loans for which it is probable at acquisition that all required payments will not be collected in accordance with contractual terms are considered PCI loans. PCI loans and leases 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. An allowance is recorded if there is additional credit deterioration after the acquisition date. Conversely, Non-PCI loans include originated commercial, originated noncommercial, purchased revolving,
	and purchased non-impaired loans, or loans that do not have a discount, due at least in part, to credit quality at the time of
	acquisition. All loans acquired in the CCBT acquisition are accounted for as PCI loans.
	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, loans are assigned to loan classes, which further disaggregate loans based upon common risk characteristics.
	Commercial – Commercial loans include construction and land development, 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.
	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.
	Noncommercial – Noncommercial 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 and revolving lines of credit that can be secured or unsecured, including personal credit cards.
	Loans and leases outstanding include the following at March 31, 2015 and December 31, 2014:
	(Dollars in thousands)	March 31, 2015			December 31, 2014
	Non-PCI loans and leases:
	Commercial:
	Construction and land development	$	608,556		$	550,568
	Commercial mortgage	7,591,745			7,552,948
	Other commercial real estate	262,293			244,875
	Commercial and industrial	2,072,414			1,988,934
	Lease financing	603,737			571,916
	Other	354,713			353,833
	Total commercial loans	11,493,458			11,263,074
	Noncommercial:
	Residential mortgage	2,524,549			2,520,542
	Revolving mortgage	2,528,257			2,561,800
	Construction and land development	170,208			120,097
	Consumer	1,127,942			1,117,454
	Total noncommercial loans	6,350,956			6,319,893
	Total non-PCI loans and leases	17,844,414			17,582,967
	PCI loans:
	Commercial:
	Construction and land development	70,049			78,079
	Commercial mortgage	653,846			577,518
	Other commercial real estate	40,841			40,193
	Commercial and industrial	24,134			27,254
	Other	2,886			3,079
	Total commercial loans	791,756			726,123
	Noncommercial:
	Residential mortgage	380,490			382,340
	Revolving mortgage	70,363			74,109
	Construction and land development	874			912
	Consumer	3,860			3,014
	Total noncommercial loans	455,587			460,375
	Total PCI loans	1,247,343			1,186,498
	Total loans and leases	$	19,091,757		$	18,769,465
	At March 31, 2015, $3.25 billion in noncovered loans with a lendable collateral value of $2.30 billion are used to secure $290.3 million in Federal Home Loan Bank ("FHLB") of Atlanta advances, resulting in additional borrowing capacity of $2.01 billion. At December 31, 2014, $3.16 billion in noncovered loans with a lendable collateral value of $2.20 billion used to secure $240.3 million in FHLB of Atlanta advances, resulting additional borrowing capacity of $1.96 billion.
	At March 31, 2015, $443.1 million of total loans and leases were covered under loss share agreements, compared to $485.3 million at December 31, 2014. At the beginning of the second quarter of 2015, the loss share protection will expire for non-single family residential loans acquired from Sun American Bank ("SAB") and all loans acquired from First Regional Bank ("FRB"). Loan balances at March 31, 2015 for the expiring agreements from SAB and FRB were $43.2 million and $53.9 million, respectively. The loss share protection for Williamsburg First National Bank non-single family residential loans with a balance of $8.4 million at March 31, 2015 will expire at the beginning of the fourth quarter of 2015.
	The unamortized discount related to the non-PCI loans and leases acquired in the Bancorporation merger totaled $55.7 million and $61.2 million at March 31, 2015 and December 31, 2014, 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. Each commercial loan is evaluated annually with more frequent evaluation of 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 no 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 effected 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, 2015 and December 31, 2014 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 and other commercial real estate loans.
Non-PCI loans and leases outstanding at March 31, 2015 and December 31, 2014 by credit quality indicator are provided below:
	March 31, 2015
(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
	development			mortgage			commercial real estate		industrial
Pass	$	590,298		$	7,341,243		$	260,592	$	1,931,078	$	597,464	$	350,060	$	11,070,735
Special mention	15,679			115,411			501		21,771		2,609		1,913		157,884
Substandard	2,291			131,672			1,049		8,806		3,284		2,690		149,792
Doubtful	—			2,039			—		4,402		329		—		6,770
Ungraded	288			1,380			151		106,357		51		50		108,277
Total	$	608,556		$	7,591,745		$	262,293	$	2,072,414	$	603,737	$	354,713	$	11,493,458
	December 31, 2014
	Non-PCI commercial loans and leases
	Construction  and land			Commercial			Other		Commercial  and		Lease financing		Other		Total non-PCI commercial loans and leases
	development			mortgage			commercial real estate		industrial
Pass	$	525,711		$	7,284,714		$	242,053	$	1,859,415	$	564,319	$	349,111	$	10,825,323
Special mention	20,025			129,247			909		27,683		3,205		1,384		182,453
Substandard	4,720			134,677			1,765		8,878		3,955		3,338		157,333
Doubtful	—			2,366			—		164		365		—		2,895
Ungraded	112			1,944			148		92,794		72		—		95,070
Total	$	550,568		$	7,552,948		$	244,875	$	1,988,934	$	571,916	$	353,833	$	11,263,074
	March 31, 2015
	Non-PCI noncommercial loans and leases
(Dollars in thousands)	Residential			Revolving			Construction		Consumer		Total non-PCI noncommercial
	mortgage			mortgage			and land				loans and leases
							development
Current	$	2,490,453		$	2,510,879		$	168,199	$	1,121,123	$	6,290,654
30-59 days past due	21,844			10,288			2,009		4,236		38,377
60-89 days past due	2,896			2,794			—		1,555		7,245
90 days or greater past due	9,356			4,296			—		1,028		14,680
Total	$	2,524,549		$	2,528,257		$	170,208	$	1,127,942	$	6,350,956
	December 31, 2014
	Non-PCI noncommercial loans and leases
	Residential			Revolving			Construction		Consumer		Total non-PCI noncommercial
	mortgage			mortgage			and land				loans and leases
							development
Current	$	2,482,281		$	2,542,807		$	119,094	$	1,110,153	$	6,254,335
30-59 days past due	23,288			11,097			370		4,577		39,332
60-89 days past due	6,018			2,433			486		1,619		10,556
90 days or greater past due	8,955			5,463			147		1,105		15,670
Total	$	2,520,542		$	2,561,800		$	120,097	$	1,117,454	$	6,319,893
PCI loans and leases outstanding at March 31, 2015 and December 31, 2014 by credit quality indicator are provided below:
	March 31, 2015
(Dollars in thousands)	PCI commercial loans
Grade:	Construction			Commercial			Other		Commercial		Other		Total PCI commercial
	and land			mortgage			commercial		and				loans
	development						real estate		industrial
Pass	$	13,832		$	333,368		$	9,727	$	13,525	$	683	$	371,135
Special mention	4,287			118,209			16,425		2,963		—		141,884
Substandard	44,663			193,435			12,948		6,739		2,132		259,917
Doubtful	4,656			8,456			1,741		513		71		15,437
Ungraded	2,611			378			—		394		—		3,383
Total	$	70,049		$	653,846		$	40,841	$	24,134	$	2,886	$	791,756
	December 31, 2014
	PCI commercial loans
	Construction			Commercial			Other		Commercial		Other		Total PCI commercial
	and land			mortgage			commercial		and				loans
	development						real estate		industrial
Pass	$	13,514		$	300,187		$	11,033	$	16,637	$	801	$	342,172
Special mention	6,063			98,724			16,271		4,137		—		125,195
Substandard	53,739			171,920			12,889		6,312		2,278		247,138
Doubtful	2,809			6,302			—		130		—		9,241
Ungraded	1,954			385			—		38		—		2,377
Total	$	78,079		$	577,518		$	40,193	$	27,254	$	3,079	$	726,123
	March 31, 2015
	PCI noncommercial loans
(Dollars in thousands)	Residential			Revolving			Construction		Consumer		Total PCI noncommercial
	mortgage			mortgage			and land				loans
							development
Current	$	320,607		$	63,579		$	592	$	3,571	$	388,349
30-59 days past due	18,742			2,800			—		130		21,672
60-89 days past due	6,804			1,019			—		13		7,836
90 days or greater past due	34,337			2,965			282		146		37,730
Total	$	380,490		$	70,363		$	874	$	3,860	$	455,587
	December 31, 2014
	PCI noncommercial loans
	Residential			Revolving			Construction		Consumer		Total PCI noncommercial
	mortgage			mortgage			and land				loans
							development
Current	$	326,589		$	68,548		$	506	$	2,582	$	398,225
30-59 days past due	11,432			1,405			—		147		12,984
60-89 days past due	10,073			345			—		25		10,443
90 days or greater past due	34,246			3,811			406		260		38,723
Total	$	382,340		$	74,109		$	912	$	3,014	$	460,375
The aging of the outstanding non-PCI loans and leases, by class, at March 31, 2015 and December 31, 2014 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, 2015
(Dollars in thousands)	30-59 days			60-89 days			90 days or greater		Total past		Current		Total loans
	past due			past due					due				and leases
Non-PCI loans and leases:
Construction and land development - commercial	$	2,709		$	712		$	1,044	$	4,465	$	604,091	$	608,556
Commercial mortgage	22,635			5,920			8,445		37,000		7,554,745		7,591,745
Other commercial real estate	583			58			196		837		261,456		262,293
Commercial and industrial	6,290			1,724			570		8,584		2,063,830		2,072,414
Lease financing	476			11			—		487		603,250		603,737
Residential mortgage	21,844			2,896			9,356		34,096		2,490,453		2,524,549
Revolving mortgage	10,288			2,794			4,296		17,378		2,510,879		2,528,257
Construction and land development - noncommercial	2,009			—			—		2,009		168,199		170,208
Consumer	4,236			1,555			1,028		6,819		1,121,123		1,127,942
Other	380			65			133		578		354,135		354,713
Total non-PCI loans and leases	$	71,450		$	15,735		$	25,068	$	112,253	$	17,732,161	$	17,844,414
	December 31, 2014
	30-59 days			60-89 days			90 days or greater		Total past		Current		Total loans
	past due			past due					due				and leases
Non-PCI loans and leases:
Construction and land development - commercial	$	1,796		$	621		$	385	$	2,802	$	547,766	$	550,568
Commercial mortgage	11,367			4,782			8,061		24,210		7,528,738		7,552,948
Other commercial real estate	206			70			102		378		244,497		244,875
Commercial and industrial	2,843			1,545			378		4,766		1,984,168		1,988,934
Lease financing	1,631			8			2		1,641		570,275		571,916
Residential mortgage	23,288			6,018			8,955		38,261		2,482,281		2,520,542
Revolving mortgage	11,097			2,433			5,463		18,993		2,542,807		2,561,800
Construction and land development - noncommercial	370			486			147		1,003		119,094		120,097
Consumer	4,577			1,619			1,105		7,301		1,110,153		1,117,454
Other	146			1,966			—		2,112		351,721		353,833
Total non-PCI loans and leases	$	57,321		$	19,548		$	24,598	$	101,467	$	17,481,500	$	17,582,967
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, 2015 and December 31, 2014 for non-PCI loans, were as follows:
	March 31, 2015						December 31, 2014
(Dollars in thousands)	Nonaccrual			Loans and			Nonaccrual		Loans and
	loans and			leases > 90			loans and		leases > 90
	leases			days and			leases		days and
				accruing					accruing
Non-PCI loans and leases:
Construction and land development - commercial	$	1,497		$	202		$	343	$	111
Commercial mortgage	26,058			764			24,720		1,003
Other commercial real estate	650			—			619		35
Commercial and industrial	5,691			294			1,741		239
Lease financing	346			—			374		2
Residential mortgage	19,238			1,153			14,242		3,191
Revolving mortgage	9,837			19			—		5,463
Construction and land development - noncommercial	—			—			—		147
Consumer	677			626			—		1,059
Other	2,052			31			1,966		—
Total non-PCI loans and leases	$	66,046		$	3,089		$	44,005	$	11,250
Purchased credit-impaired loans (PCI) loans
The following table relates to PCI loans acquired in the CCBT acquisition and summarizes the contractually required payments, which include principal and interest, expected cash flows to be collected, and the fair value of PCI loans and leases at the acquisition date.
(Dollars in thousands)
Contractually required payments	$	251,800
Cash flows expected to be collected	$	204,480
Fair value of loans at acquisition	$	149,294
The recorded fair values of PCI loans acquired in the CCBT acquisition as of the acquisition date are as follows:
(Dollars in thousands)
Commercial:
Construction and land development	$	4,221
Commercial mortgage	125,202
Other commercial real estate	3,132
Commercial and industrial	3,049
Total commercial loans	135,604
Noncommercial:
Residential mortgage	12,050
Consumer	1,640
Total noncommercial loans	13,690
Total PCI loans and leases	$	149,294
The following table provides changes in the carrying value of all purchased credit-impaired loans during the three months ended March 31, 2015 and March 31, 2014:
(Dollars in thousands)	2015			2014
Balance at January 1	$	1,186,498		$	1,029,426
Fair value of acquired loans	149,294			316,327
Accretion	25,067			30,200
Payments received and other changes, net	(113,516		)	(105,135		)
Balance at March 31	$	1,247,343		$	1,270,818
Unpaid principal balance at March 31	$	2,092,936		$	1,727,492
The carrying value of loans on the cost recovery method was $13.0 million at March 31, 2015 and $33.4 million at December 31, 2014. 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.
For PCI loans, improved cash flow estimates and receipt of unscheduled loan payments result in the reclassification of nonaccretable difference to accretable yield. Accretable yield resulting from the improved ability to estimate future cash flows generally does not represent amounts previously identified as nonaccretable difference.
The following table documents changes to the amount of accretable yield for the first three months of 2015 and 2014.
(Dollars in thousands)	2015			2014
Balance at January 1	$	418,160		$	439,990
Additions from acquisitions	55,186			84,295
Accretion	(25,067		)	(30,200		)
Reclassifications from nonaccretable difference	1,294			6,048
Changes in expected cash flows that do not affect nonaccretable difference	(27,287		)	(9,888		)
Balance at March 31	$	422,286		$	490,245

Allowance_for_Loan_and_Lease_L

Allowance for Loan and Lease Losses	3 Months Ended
	Mar. 31, 2015
Allowance for Loan and Lease Losses, Adjustments, Net [Abstract]
Allowance	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, 2015 and March 31, 2014:
		Three months ended March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other commercial real estate			Commercial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage						and industrial				financing						mortgage			mortgage			and land
		development																										development
		- commercial																										- non-
																												commercial
	Non-PCI Loans
	Allowance for loan and lease losses:
	Balance at January 1	$	11,961			$	85,189		$	732		$	30,727			$	4,286		$	3,184		$	10,661		$	18,650		$	892		$	16,555		$	182,837
	Provision	1,103				(3,679		)	458			7,546				11			(218		)	813			(462		)	118			2,966			8,656
	Charge-offs	(18		)		(233		)	(169		)	(1,713		)		(15		)	—			(284		)	(793		)	(22		)	(2,783		)	(6,030		)
	Recoveries	62				761			10			394				11			15			138			134			68			878			2,471
	Balance at March 31	$	13,108			$	82,038		$	1,031		$	36,954			$	4,293		$	2,981		$	11,328		$	17,529		$	1,056		$	17,616		$	187,934
		Three months ended March 31, 2014
		Construction				Commercial			Other commercial real estate			Commercial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage						and industrial				financing						mortgage			mortgage			and land
		development																										development
		- commercial																										- non-
																												commercial
	Balance at January 1	$	10,335			$	100,257		$	1,009		$	22,362			$	4,749		$	190		$	10,511		$	16,239		$	681		$	13,541		$	179,874
	Provision	1,885				(6,979		)	(74		)	1,976				(524		)	272			609			1,353			577			1,275			370
	Charge-offs	—				(168		)	—			(496		)		(58		)	(8		)	(184		)	(1,260		)	(71		)	(2,177		)	(4,422		)
	Recoveries	26				1,107			10			179				16			—			8			76			62			643			2,127
	Balance at March 31	$	12,246			$	94,217		$	945		$	24,021			$	4,183		$	454		$	10,944		$	16,408		$	1,249		$	13,282		$	177,949
	The commercial mortgage loan class had a net provision credit of $3.7 million for the three months ended March 31, 2015, compared to a net provision credit of $7.0 million for the same period of 2014. The decrease in the net provision credit was primarily due to loan growth in the first quarter of 2015 compared to a decline in loans in the first quarter of 2014. This loan class continues to experience credit quality improvement, which drives the credit in provision.
	The provision expense for commercial and industrial loans totaled $7.5 million for the three months ended March 31, 2015, compared to $2.0 million for the same period of 2014. Loan growth of $83.5 million since December 31, 2014 was the primary reason for the increase in provision expense.
	The revolving mortgage loan class had a net provision credit of $0.5 million for the three months ended March 31, 2015, compared to provision expense of $1.4 million for the three months ended March 31, 2014. The decrease was due to lower charge-offs and lower credit default trends within the loan class.
	The provision for consumer loans totaled $3.0 million and $1.3 million for the three months ended March 31, 2015 and March 31, 2014, respectively. The increase in provision expense was primarily due to loan growth in the first quarter of 2015 compared to a decline in loans in the first quarter of 2014.
	The following tables present the allowance for non-PCI loan losses and the recorded investment in loans, by loan class, based on impairment method as of March 31, 2015 and December 31, 2014:
		March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other			Commercial and industrial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial							financing						mortgage			mortgage			and land
		development							real estate																			development
		- commercial																										- non-commercial
	Allowance for loan and lease losses:
	ALLL for loans and leases individually evaluated for impairment	$	182			$	7,494		$	104		$	2,809			$	236		$	1,955		$	1,177		$	108		$	90		$	531		$	14,686
	ALLL for loans and leases collectively evaluated for impairment	12,926				74,544			927			34,145				4,057			1,026			10,151			17,421			966			17,085			173,248
	Total allowance for loan and lease losses	$	13,108			$	82,038		$	1,031		$	36,954			$	4,293		$	2,981		$	11,328		$	17,529		$	1,056		$	17,616		$	187,934
	Loans and leases:
	Loans and leases individually evaluated for impairment	$	2,972			$	77,291		$	543		$	13,969			$	1,492		$	1,977		$	15,195		$	2,922		$	733		$	984		$	118,078
	Loans and leases collectively evaluated for impairment	605,584				7,514,454			261,750			2,058,445				602,245			352,736			2,509,354			2,525,335			169,475			1,126,958			17,726,336
	Total loan and leases	$	608,556			$	7,591,745		$	262,293		$	2,072,414			$	603,737		$	354,713		$	2,524,549		$	2,528,257		$	170,208		$	1,127,942		$	17,844,414
		December 31, 2014
	(Dollars in thousands)	Construction				Commercial			Other			Commercial and industrial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial							financing						mortgage			mortgage			and land
		development							real estate																			development
		- commercial																										- non-commercial
	Allowance for loan and lease losses:
	ALLL for loans and leases individually evaluated for impairment	$	92			$	8,610		$	112		$	1,743			$	150		$	1,972		$	1,360		$	1,052		$	71		$	555		$	15,717
	ALLL for loans and leases collectively evaluated for impairment	11,869				76,579			620			28,984				4,136			1,212			9,301			17,598			821			16,000			167,120
	Total allowance for loan and lease losses	$	11,961			$	85,189		$	732		$	30,727			$	4,286		$	3,184		$	10,661		$	18,650		$	892		$	16,555		$	182,837
	Loans and leases:
	Loans and leases individually evaluated for impairment	$	1,620			$	82,803		$	584		$	11,040			$	623		$	2,000		$	14,913		$	3,675		$	1,340		$	995		$	119,593
	Loans and leases collectively evaluated for impairment	548,948				7,470,145			244,291			1,977,894				571,293			351,833			2,505,629			2,558,125			118,757			1,116,459			17,463,374
	Total loan and leases	$	550,568			$	7,552,948		$	244,875		$	1,988,934			$	571,916		$	353,833		$	2,520,542		$	2,561,800		$	120,097		$	1,117,454		$	17,582,967
	The following tables show the activity in the allowance for PCI loan and lease losses by loan class for the three months ended March 31, 2015 and March 31, 2014.
		Three months ended March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
		development -							real estate			industrial										development -
		commercial																				noncommercial
	PCI Loans
Allowance for loan and lease losses:
Balance at January 1	$	150			$	10,135		$	75		$	1,240			$	5,820		$	3,999		$	183		$	27		$	21,629
Provision	191				(925		)	119			(1,031		)		(863		)	(655		)	(152		)	452			(2,864		)
Charge-offs	—				(334		)	—			(198		)		(85		)	(73		)	—			(456		)	(1,146		)
Recoveries	—				—			—			—				—			—			—			—			—
Balance at March 31	$	341			$	8,876		$	194		$	11			$	4,872		$	3,271		$	31		$	23		$	17,619
	Three months ended March 31, 2014
(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
	and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
	development -							real estate			industrial										development -
	commercial																				noncommercial
Balance at January 1	$	1,320			$	29,906		$	1,354		$	5,275			$	11,802		$	2,959		$	682		$	222		$	53,520
Provision	3,355				(3,386		)	(150		)	(336		)		(2,300		)	634			(99		)	9			(2,273		)
Charge-offs	(199		)		(3,517		)	—			(2,683		)		262			(100		)	—			(17		)	(6,254		)
Recoveries	—				—			—			—				—			—			—			—			—
Balance at March 31	$	4,476			$	23,003		$	1,204		$	2,256			$	9,764		$	3,493		$	583		$	214		$	44,993
The following tables show the ending balances of PCI loans and leases and related allowance by class of loans as of March 31, 2015 and December 31, 2014:
	March 31, 2015
(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
	and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
	development -							real estate			industrial										development -
	commercial																				noncommercial
ALLL for loans and leases acquired with deteriorated credit quality	$	341			$	8,876		$	194		$	11			$	4,872		$	3,271		$	31		$	23		$	17,619
Loans and leases acquired with deteriorated credit quality	70,049				653,846			40,841			24,134				380,490			70,363			874			6,746			1,247,343
	December 31, 2014
(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
	and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
	development -							real estate			industrial										development -
	commercial																				noncommercial
ALLL for loans and leases acquired with deteriorated credit quality	$	150			$	10,135		$	75		$	1,240			$	5,820		$	3,999		$	183		$	27		$	21,629
Loans and leases acquired with deteriorated credit quality	78,079				577,518			40,193			27,254				382,339			74,109			912			6,094			1,186,498
As of March 31, 2015, and December 31, 2014, $438.2 million and $285.6 million, respectively, in PCI loans experienced an adverse change in expected cash flows since the date of acquisition. The corresponding valuation reserve was $17.6 million and $21.6 million, respectively.
The following tables provide information on non-PCI impaired loans and leases, exclusive of loans and leases evaluated collectively as a homogenous group, as of March 31, 2015 and December 31, 2014 including interest income recognized in the period during which the loans and leases were considered impaired.
	March 31, 2015
(Dollars in thousands)	With a				With no			Total			Unpaid				Related
	recorded				recorded						principal				allowance
	allowance				allowance						balance				recorded
Non-PCI impaired loans and leases:
Construction and land development - commercial	$	2,114			$	858		$	2,972		$	4,228			$	182
Commercial mortgage	53,220				24,071			77,291			81,826				7,494
Other commercial real estate	104				439			543			847				104
Commercial and industrial	13,123				846			13,969			14,939				2,809
Lease financing	1,221				271			1,492			1,492				236
Other	1,977				—			1,977			1,977				1,955
Residential mortgage	8,662				6,533			15,195			15,852				1,177
Revolving mortgage	1,439				1,483			2,922			3,925				108
Construction and land development - noncommercial	733				—			733			733				90
Consumer	904				80			984			1,004				531
Total non-PCI impaired loans and leases	$	83,497			$	34,581		$	118,078		$	126,823			$	14,686
	December 31, 2014
(Dollars in thousands)	With a				With no			Total			Unpaid				Related
	recorded				recorded						principal				allowance
	allowance				allowance						balance				recorded
Non-PCI impaired loans and leases:
Construction and land development - commercial	$	996			$	624		$	1,620		$	6,945			$	92
Commercial mortgage	57,324				25,479			82,803			87,702				8,610
Other commercial real estate	112				472			584			913				112
Commercial and industrial	10,319				721			11,040			12,197				1,743
Lease financing	319				304			623			623				150
Other	2,000				—			2,000			2,000				1,972
Residential mortgage	10,198				4,715			14,913			15,746				1,360
Revolving mortgage	3,675				—			3,675			4,933				1,052
Construction and land development - noncommercial	1,077				263			1,340			1,340				71
Consumer	987				8			995			1,067				555
Total non-PCI impaired loans and leases	$	87,007			$	32,586		$	119,593		$	133,466			$	15,717
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, 2015 and March 31, 2014:
	Three months ended March 31, 2015							Three months ended March 31, 2014
(Dollars in thousands)	Average				Interest income recognized			Average			Interest income recognized
	balance							balance
Non-PCI impaired loans and leases:
Construction and land development - commercial	$	3,052			$	35		$	1,031		$	15
Commercial mortgage	80,553				769			94,547			1,120
Other commercial real estate	551				1			1,796			21
Commercial and industrial	14,229				103			10,234			118
Lease financing	1,590				18			284			4
Other	1,990				—			—			—
Residential mortgage	15,364				125			16,482			174
Revolving mortgage	2,986				16			3,892			27
Construction and land development - noncommercial	658				7			2,322			29
Consumer	1,022				19			1,059			5
Total non-PCI impaired loans and leases	$	121,995			$	1,093		$	131,647		$	1,513
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 grant. 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, Loans and Debt Securities Acquired with Deteriorated Credit Quality, 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 modifications 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, 2015										December 31, 2014
(Dollars in thousands)	Accruing				Nonaccruing			Total			Accruing				Nonaccruing			Total
Commercial loans
Construction and land development -	$	3,425			$	490		$	3,915		$	2,591			$	446		$	3,037
commercial
Commercial mortgage	88,889				11,326			100,215			92,184				8,937			101,121
Other commercial real estate	2,123				423			2,546			2,374				449			2,823
Commercial and industrial	9,248				4,768			14,016			9,864				664			10,528
Lease	1,163				329			1,492			258				365			623
Other	—				—			—			34				—			34
Total commercial TDRs	104,848				17,336			122,184			107,305				10,861			118,166
Noncommercial
Residential	23,060				5,097			28,157			22,597				4,655			27,252
Revolving mortgage	1,871				1,112			2,983			3,675				—			3,675
Construction and land development -	733				—			733			1,391				—			1,391
noncommercial
Consumer and other	954				1,980			2,934			995				—			995
Total noncommercial TDRs	26,618				8,189			34,807			28,658				4,655			33,313
Total TDRs	$	131,466			$	25,525		$	156,991		$	135,963			$	15,516		$	151,479
The majority of TDRs are included in the special mention, substandard or doubtful grading categories, which results in more elevated loss expectations when determining 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, TDRs over $500,000 and graded substandard or lower are evaluated individually for impairment through a review of collateral values.
The following table shows the accrual status of non-PCI and PCI TDRs.
(Dollars in thousands)	March 31, 2015				December 31, 2014
Accruing TDRs:
PCI	$	44,582			$	44,647
Non-PCI	86,884				91,316
Total accruing TDRs	131,466				135,963
Nonaccruing TDRs:
PCI	1,999				2,225
Non-PCI	23,526				13,291
Total nonaccruing TDRs	25,525				15,516
All TDRs:
PCI	46,581				46,872
Non-PCI	110,410				104,607
Total TDRs	$	156,991			$	151,479
The following tables provide the types of TDRs made during the three months ended March 31, 2015 and March 31, 2014, as well as a summary of loans that were modified as a TDR during the twelve months ended March 31, 2015 and March 31, 2014 that subsequently defaulted during the three months ended March 31, 2015 and March 31, 2014. 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, 2015										Three months ended March 31, 2014
	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
Interest only period provided
Commercial mortgage	—		$	—			—	$	—		4		$	1,911			2	$	410
Commercial and industrial	1		3,796				1	3,796			1		196				—	—
Lease financing	—		—				—	—			2		146				—	—
Total interest only	1		3,796				1	3,796			7		2,253				2	410
Loan term extension
Construction and land development - commercial	1		220				1	220			—		—				—	—
Commercial mortgage	3		535				—	—			5		2,620				—	—
Lease financing	—		—				—	—			2		234				—	—
Revolving mortgage	1		10				—	—			—		—				—	—
Residential mortgage	—		—				—	—			5		338				—	—
Consumer	1		5				—	—			—		—				1	41
Total loan term extension	6		770				1	220			12		3,192				1	41
Below market interest rate
Construction and land development - commercial	2		47				—	—			1		82				—	—
Commercial mortgage	9		3,541				2	733			12		4,677				1	449
Commercial and industrial	3		172				—	—			2		110				—	—
Residential mortgage	23		708				2	45			8		451				3	127
Revolving mortgage	2		18				—	—			5		278				—	—
Construction and land development - noncommercial	2		396				—	—			—		—				—	—
Consumer	3		34				—	—			—		—				—	—
Other	1		1,950				—	—			—		—				—	—
Total below market interest rate	45		6,866				4	778			28		5,598				4	576
Discharged from bankruptcy
Commercial mortgage	—		—				—	—			1		1,003				—	—
Residential mortgage	2		68				—	—			7		708				2	288
Revolving mortgage	5		218				2	147			4		229				—	—
Construction and land development-noncommercial	—		—				—	—			1		62				—	—
Consumer	—		—				—	—			1		18				—	—
Total discharged from bankruptcy	7		286				2	147			14		2,020				2	288
Total non-PCI restructurings	59		$	11,718			8	$	4,941		61		$	13,063			9	$	1,315
	Three months ended March 31, 2015										Three months ended March 31, 2014
	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 mortgage	—		$	—			—	$	—		2		$	15,906			2	$	15,906
Total interest only	—		—				—	—			2		15,906				2	15,906
Loan term extension
Construction and land development - commercial	—		—				—	—			1		281				—	—
Total loan term extension	—		—				—	—			1		281				—	—
Below market interest rate
Construction and land development - commercial	—		—				—	—			1		37				—	—
Commercial mortgage	—		—				—	—			4		5,439				1	47
Commercial and industrial	—		—				1	65			—		—				—	—
Residential mortgage	7		470				—	—			1		102				1	436
Total below market interest rate	7		470				1	65			6		5,578				2	31,812
Total PCI restructurings	7		$	470			1	$	65		9		$	21,765			4	$	47,718
For the three months ended March 31, 2015 and March 31, 2014, the recorded investment in TDRs subsequent to modification was not materially impacted by the modification since forgiveness of principal is not a restructuring option frequently used by BancShares.

Other_Real_Estate_Owned

Other Real Estate Owned	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Other Real Estate Owned	OTHER REAL ESTATE OWNED (OREO)
	The following table explains changes in other real estate owned during the three months ended March 31, 2015 and March 31, 2014.
	(Dollars in thousands)	Covered			Noncovered			Total
	Balance at December 31, 2013	$	47,081		$	36,898		$	83,979
	Additions	1,514			3,318			4,832
	Additions acquired in the 1st Financial merger	—			11,591			11,591
	Sales	(4,512		)	(5,854		)	(10,366		)
	Writedowns	(2,228		)	(1,449		)	(3,677		)
	Balance at March 31, 2014	$	41,855		$	44,504		$	86,359
	Balance at December 31, 2014	$	22,982		$	70,454		$	93,436
	Additions	4,244			17,084			21,328
	Sales	(8,970		)	(13,573		)	(22,543		)
	Writedowns	(954		)	(1,275		)	(2,229		)
	Balance at March 31, 2015	$	17,302		$	72,690		$	89,992
	At March 31, 2015 and December 31, 2014, BancShares had $23.2 million and $29.0 million, respectively, of foreclosed residential real estate property in OREO and $20.1 million and $24.8 million, respectively, in recorded investment in consumer mortgage loans collateralized by residential real estate property in the process of foreclosure.

Receivable_from_FDIC_for_Loss_

Receivable from FDIC for Loss Share Agreements	3 Months Ended
	Mar. 31, 2015
Receivable From FDIC For Loss Share Agreements [Abstract]
Receivable from FDIC for Loss Share Agreements	FDIC LOSS SHARE RECEIVABLE
	The following table provides changes in the receivable from the FDIC for the three-month periods ended March 31, 2015 and March 31, 2014.
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Beginning balance	$	28,701		$	93,397
	Amortization	(5,031		)	(17,744		)
	Cash payments to FDIC	5,762			3,490
	Post-acquisition adjustments	(8,092		)	(4,359		)
	Ending balance	$	21,340		$	74,784
	The receivable from the FDIC for loss share agreements is measured separately from the related covered assets and is recorded at fair value at the acquisition date using projected cash flows based on the expected reimbursements for losses and the applicable loss share percentages. See Note L for information related to FCB's recorded payable to the FDIC for loss share agreements.
	Amortization reflects changes in the FDIC loss share receivable due to improvements in expected cash flows that are being recognized over the remaining term of the loss share agreement. Cash payments to FDIC represent the net impact of loss share loan recoveries, charge-offs and related expenses as calculated and reported in FDIC loss share certificates. Post-acquisition adjustments represent the net change in loss estimates related to acquired loans and covered OREO as a result of changes in expected cash flows and the ALLL related to those covered loans. For loans covered by loss share agreements, subsequent decreases in the amount expected to be collected from the borrower or collateral liquidation result in a provision for loan and lease losses, an increase in the ALLL and a proportional adjustment to the receivable from the FDIC for the estimated amount to be reimbursed. Subsequent increases in the amount expected to be collected from the borrower or collateral liquidation result in the reversal of some or all previously recorded provision for loan and lease losses, a decrease in the related ALLL and a proportional adjustment to the receivable from the FDIC, or prospective adjustment to the accretable yield and the related receivable from the FDIC if no provision for loan and lease losses had been recorded previously. The loss share agreements for FRB and non-single family residential loans acquired from SAB will expire at the beginning of the second quarter of 2015. The loss share agreements for non-single family residential loans for Williamsburg First National Bank will expire at the beginning of the fourth quarter of 2015.

Estimated_Fair_Values

Estimated Fair Values	3 Months Ended
	Mar. 31, 2015
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 to these valuation methods are subjective in nature, involve uncertainties and require significant judgment and therefore cannot be determined with precision. Accordingly, the derived fair value estimates presented below are not necessarily indicative of the amounts BancShares could 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 generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable 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.
	Valuation adjustments, such as those pertaining to counterparty and BancShares' own credit quality and liquidity, may be necessary to ensure that assets and liabilities are recorded at fair value. Credit valuation adjustments are made when market pricing does not accurately reflect the counterparty's credit quality. As determined by BancShares management, liquidity valuation adjustments may be made to the fair value of certain assets to reflect the uncertainty in the pricing and trading of the instruments when we are unable to observe recent market transactions for identical or similar instruments.
	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.
	The methodologies used to estimate the fair value of financial assets and financial liabilities are discussed below:
	Investment securities available for sale. U.S.Treasury, government agency, mortgage-backed securities, municipal securities and trust preferred securities are generally measured at fair value using a third party pricing service or recent comparable market transactions in similar or identical securities and are classified as level 2 instruments.
	Loans held for sale. Certain residential real estate loans are originated to be sold to investors, which are carried at fair value as BancShares elected the fair value option on loans held for sale in 2014. The fair value is based on quoted market prices for similar types of loans. Accordingly, the inputs used to calculate fair value of residential real estate loans held for sale are classified as level 2 inputs.
	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. An additional valuation adjustment is made for liquidity. The inputs used in the fair value measurements for loans and leases are considered level 3 inputs.
	Receivable from the FDIC for loss share agreements. Fair value is estimated based on discounted future cash flows using current discount rates. Due to post-acquisition improvements in expected losses, significant portions of the FDIC receivable will be recovered through amortization of the receivable over the remaining life of the loss share agreement rather than by cash flows from the FDIC. The estimated amounts to be amortized in future periods have no fair value. The inputs used in the fair value measurement for the FDIC receivable are considered level 3 inputs. The FDIC loss share agreements are not transferable and, accordingly, there is no market for this receivable.
	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.
	Preferred stock issued under the TARP program and other acquired financial assets. Preferred securities issued under the Troubled Asset Recovery Program are recorded at cost and are evaluated quarterly for impairment based on the ultimate recoverability of the purchase price. The fair value of these securities is derived from a third-party proprietary model that is considered to be a level 3 input. Other acquired financial assets represent acquired investments in various entities for Community Reinvestment Act and correspondent banking purposes. These investments were recorded at fair value at acquisition date based on 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 loss share agreements. The fair value of the payable to the FDIC for loss share agreements is determined by the projected cash flows based on expected payments to the FDIC in accordance with the loss share 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.
	Interest rate swap. Under the terms of the existing cash flow hedge, BancShares pays a fixed payment to the counterparty in exchange for receipt of a variable payment that is determined based on the three-month LIBOR rate. The fair value of the cash flow hedge is, therefore, based on projected LIBOR rates for the duration of the hedge, values that, while observable in the market, are subject to adjustment due to pricing considerations for the specific instrument. The inputs used in the fair value measurement of the interest rate swap are considered level 2 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, 2015 and December 31, 2014. 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.
	(Dollars in thousands)	March 31, 2015				December 31, 2014
		Carrying value		Fair value		Carrying value		Fair value
	Cash and due from banks	$	495,901	$	495,901	$	604,182	$	604,182
	Overnight investments	2,458,923		2,458,923		1,724,919		1,724,919
	Investment securities available for sale	7,045,109		7,045,109		7,171,917		7,171,917
	Investment securities held to maturity	441		459		518		544
	Loans held for sale	66,508		66,508		63,696		63,696
	Net loans and leases	18,886,204		18,359,306		18,564,999		18,046,497
	Receivable from the FDIC for loss share agreements (1)	21,340		14,407		28,701		18,218
	Income earned not collected	63,165		63,165		57,254		57,254
	Federal Home Loan Bank stock	30,291		30,291		39,113		39,113
	Preferred stock and other acquired financial assets	13,689		14,688		13,689		14,708
	Mortgage servicing rights	16,436		16,719		16,688		16,736
	Deposits	26,300,830		25,718,225		25,678,577		25,164,683
	Short-term borrowings	941,850		941,850		987,184		987,184
	Long-term obligations	468,180		486,960		351,320		367,732
	Payable to the FDIC for loss share agreements	118,645		126,113		116,535		122,168
	Accrued interest payable	8,370		8,370		8,194		8,194
	Interest rate swap	3,761		3,761		4,337		4,337
	(1) The fair value of the FDIC receivable excludes receivable related to accretable yield to be amortized in prospective periods.
	Among BancShares’ assets and liabilities, investment securities available for sale, loans held for sale and interest rate swaps accounted for as cash flow hedges are reported at their fair values on a recurring basis. Certain other assets are adjusted to their fair value on a nonrecurring basis, including impaired loans, OREO, goodwill, which is 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.
	For assets and liabilities carried at fair value on a recurring basis, the following table provides fair value information as of March 31, 2015 and December 31, 2014.
		March 31, 2015
				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	$	2,246,966	$	—	$	2,246,966	$	—
	Government agency	990,894		—		990,894		—
	Mortgage-backed securities	3,807,249		—		3,807,249		—
	Total investment securities available for sale	7,045,109		—		7,045,109		—
	Loans held for sale	66,508		—		66,508		—
	Liabilities measured at fair value
	Interest rate swaps accounted for as cash flow hedges	$	3,761	$	—	$	3,761	$	—
		December 31, 2014
				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	$	2,629,670	$	—	$	2,629,670	$	—
	Government agency	908,817		—		908,817		—
	Mortgage-backed securities	3,633,304		—		3,633,304		—
Municipal securities	126		—		126		—
Total investment securities available for sale	7,171,917		—		7,171,917		—
Loans held for sale	63,696		—		63,696		—
Liabilities measured at fair value
Interest rate swaps accounted for as cash flow hedges	$	4,337	$	—	$	4,337	$	—
There were no transfers between levels during the three months ended March 31, 2015.
Fair Value Option
Beginning in the fourth quarter of 2014, BancShares elected the fair value option for residential real estate loans held for sale. 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 following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for residential real estate loans held for sale measured at fair value as of March 31, 2015 and December 31, 2014.
	March 31, 2015
(Dollars in thousands)	Fair Value		Aggregate Unpaid Principal Balance		Difference
Loans held for sale	$	66,508	$	65,378	$	1,130
	December 31, 2014
	Fair Value		Aggregate Unpaid Principal Balance		Difference
Loans held for sale	$	63,696	$	62,996	$	700
No loans held for sale were 90 or more days past due or on nonaccrual status as of March 31, 2015 or December 31, 2014.
The changes in fair value for residential real estate loans held for sale for which we elected the fair value option are included in the table below for the three months ended March 31, 2015.
	Three months ended March 31, 2015
(Dollars in thousands)	Gains(Losses) From Fair Value Changes
Loans held for sale	$	430
The changes in fair value in the table above are recorded as a component of mortgage income on the Consolidated Income Statement.
Certain other assets are adjusted to their fair value on a nonrecurring basis, including impaired loans, OREO, goodwill, which is 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 10 and 14 percent applied for estimated holding and selling costs and other external factors that may impact the marketability of the property. Impaired loans are assigned to an asset manager and monitored monthly for significant changes since the last valuation. If significant changes are noted, the asset manager orders a new valuation or adjusts the valuation accordingly. Expected cash flows are determined using expected payment information at the individual loan level, discounted using the effective interest rate. The effective interest rates generally range between 2 and 16 percent.
OREO is measured and reported at fair value using collateral valuations. Collateral values are determined using appraisals or other third-party value estimates of the subject property with discounts generally between 10 and 14 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. The asset manager uses the information gathered from brokers and other market sources to identify any significant changes in the market or the subject property as they occur. Valuations are then adjusted or new appraisals are ordered to ensure the reported values reflect the most current information. OREO that has been acquired or written down in the current year is deemed to be at fair value and included in the table below.
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, are used to determine the fair value. See Note H for further information on the discount rates, prepayment rates and the weighted average cost to service the loans.
For financial assets and liabilities carried at fair value on a nonrecurring basis, the following table provides fair value information as of March 31, 2015 and December 31, 2014.
	March 31, 2015
			Fair value measurements using:
(Dollars in thousands)	Fair value		Level 1 inputs		Level 2 inputs		Level 3 inputs
Impaired loans	$	69,749	$	—	$	—	$	69,749
Other real estate not covered under loss share agreements remeasured during current year	17,034		—		—		17,034
Other real estate covered under loss share agreements remeasured during current year	3,714		—		—		3,714
Mortgage servicing rights	14,225		—		—		14,225
	December 31, 2014
			Fair value measurements using:
	Fair value		Level 1 inputs		Level 2 inputs		Level 3 inputs
Impaired loans	$	73,170	$	—	$	—	$	73,170
Other real estate not covered under loss share agreements remeasured during current year	40,714		—		—		40,714
Other real estate covered under loss share agreements remeasured during current year	17,664		—		—		17,664
Mortgage servicing rights	13,562		—		—		13,562
No financial liabilities were carried at fair value on a nonrecurring basis as of March 31, 2015 and December 31, 2014.

Employee_Benefit_Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2015
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS
	BancShares sponsors noncontributory defined benefit pension plans for its qualifying employees (BancShares Plan) and legacy Bancorporation employees (Bancorporation Plan). Net periodic benefit cost is a component of employee benefits expense.
	BancShares Plan
	For the three months ended March 31, 2015 and 2014, the components of net periodic benefit cost are as follows:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Service cost	$	3,600		$	3,381
	Interest cost	6,748			6,556
	Expected return on assets	(8,295		)	(7,812		)
	Amortization of prior service cost	53			53
	Amortization of net actuarial loss	2,833			1,546
	Net periodic benefit cost	$	4,939		$	3,724
	Bancorporation Plan
	For the three months ended March 31, 2015, the components of net periodic benefit cost are as follows:
		Three months ended March 31
	(Dollars in thousands)	2015
	Service cost	$	933
	Interest cost	1,628
	Expected return on assets	(2,869		)
	Amortization of prior service cost	—
	Amortization of net actuarial loss	—
	Net periodic benefit cost	$	(308	)
	No contributions were made during the three months ended March 31, 2015 to the BancShares or Bancorporation pension plans. BancShares does not expect to make any contributions to either of the defined benefit pension plans during the remainder of 2015.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
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. At March 31, 2015, BancShares had unused commitments totaling $7.57 billion, compared to $7.19 billion at December 31, 2014. Total unfunded commitments relating to investments in affordable housing projects totaled $22.6 million and $16.8 million at March 31, 2015 and December 31, 2014, respectively, and are included in other liabilities on BancShares' Consolidated Balance Sheets.
	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. To mitigate its risk, BancShares’ follows its credit policies in the issuance of standby letters of credit. At March 31, 2015 and December 31, 2014, BancShares had standby letters of credit amounting to $75.0 million and $77.4 million, respectively. 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.
	Pursuant to standard representations and warranties relating to residential mortgage loan sales, 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 becomes nonperforming within 120 days of its sale, the investor may require BancShares to repurchase the loan or to repay a portion of the sale proceeds. Other liabilities included reserves of $3.1 million and $3.2 million as of March 31, 2015 and December 31, 2014, respectively, for estimated losses arising from these standard representation and warranty provisions.
	BancShares has recorded a receivable from the FDIC totaling $21.3 million and $28.7 million as of March 31, 2015 and December 31, 2014, respectively, for the expected reimbursement of losses on assets covered under the various loss share agreements. These loss share agreements impose certain obligations on us that, in the event of noncompliance, could result in the delay or disallowance of some or all of our rights under those agreements. Requests for reimbursement are subject to FDIC review and may be delayed or disallowed for noncompliance. The loss share agreements are subject to interpretation by both the FDIC and BancShares, and disagreements may arise regarding coverage of losses, expenses and contingencies.
	The loss share agreements for five FDIC-assisted transactions include provisions related to contingent 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. The clawback liability is estimated by discounting estimated future payments and is recorded in the Consolidated Balance Sheets as a payable to the FDIC under the relevant loss share agreements. As of March 31, 2015 and December 31, 2014, the estimated clawback liability was $118.6 million and $116.5 million, respectively.
	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 FDIC-assisted 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.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2015
Summary of Derivative Instruments [Abstract]
Derivatives	DERIVATIVES
	At March 31, 2015, BancShares had an interest rate swap entered into during 2011 that qualifies as a cash flow hedge under GAAP. For all periods presented, the fair value of the outstanding derivative is included in other liabilities in the consolidated balance sheets, and the net change in fair value is included in the consolidated statements of cash flows under the caption net change in other liabilities.
	The following table provides the notional amount of the interest rate swap and the fair value of the liability as of March 31, 2015 and December 31, 2014.
		March 31, 2015				December 31, 2014
	(Dollars in thousands)	Notional  amount		Estimated fair value of liability		Notional  amount		Estimated fair value of liability
	2011 interest rate swap hedging variable rate exposure on trust preferred securities 2011-2016	$	93,500	$	3,761	$	93,500	$	4,337
	The interest rate swap is used for interest rate risk management purposes and converts variable-rate exposure on outstanding debt to a fixed rate. The interest rate swap has a notional amount of $93.5 million, representing the amount of variable rate trust preferred capital securities issued during 2006 and still outstanding at the swap inception date. The interest rate swap hedges interest payments through June 2016 and requires fixed-rate payments by BancShares at 5.50 percent in exchange for variable-rate payments of 175 basis points above the three-month LIBOR, which is equal to the interest paid to the holders of the trust preferred capital securities. Settlement of the swap occurs quarterly. As of March 31, 2015 and December 31, 2014, collateral with a fair value of $7.0 million was pledged to secure the existing obligation under the interest rate swap.
	For cash flow hedges, the effective portion of the gain or loss due to changes in the fair value of the derivative hedging instrument is included in other comprehensive income, while the ineffective portion, representing the excess of the cumulative change in the fair value of the derivative over the cumulative change in expected future discounted cash flows on the hedged transaction, is recorded in the consolidated income statement. BancShares’ interest rate swap has been fully effective since inception. Therefore, changes in the fair value of the interest rate swap have had no impact on net income. For the three months ended March 31, 2015 and 2014, BancShares recognized interest expense of $0.8 million during both periods, resulting from incremental interest paid to the interest rate swap counterparty, none of which related to ineffectiveness.
	BancShares monitors the credit risk of the interest rate swap counterparty.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME
	Accumulated other comprehensive income (loss) included the following as of March 31, 2015 and December 31, 2014:
		March 31, 2015										December 31, 2014
	(Dollars in thousands)	Accumulated				Deferred			Accumulated			Accumulated			Deferred			Accumulated
		other				tax expense			other			other			tax expense			other
		comprehensive				(benefit)			comprehensive			comprehensive			(benefit)			comprehensive
		income (loss)							income (loss),			gain (loss)						gain (loss),
									net of tax									net of tax
	Unrealized gains on investment securities available for sale, net	$	33,632			$	13,081		$	20,551		$	8,343		$	3,245		$	5,098
	Unrealized loss on cash flow hedge	(3,761		)		(1,451		)	(2,310		)	(4,337		)	(1,673		)	(2,664		)
	Funded status of defined benefit plan	(87,810		)		(34,158		)	(53,652		)	(90,696		)	(35,281		)	(55,415		)
	Total	$	(57,939	)		$	(22,528	)	$	(35,411	)	$	(86,690	)	$	(33,709	)	$	(52,981	)
	The following table highlights changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2015 and March 31, 2014:
		Three months ended March 31, 2015
	(Dollars in thousands)	Unrealized gains on available for sale securities1				Gains (losses) on cash flow hedges1			Defined benefit pension items1			Total
	Beginning balance	$	5,098			$	(2,664	)	$	(55,415	)	$	(52,981	)
	Other comprehensive income before reclassifications	18,602				354			—			18,956
	Amounts reclassified from accumulated other comprehensive (loss) income	(3,149		)		—			1,763			(1,386		)
	Net current period other comprehensive income	15,453				354			1,763			17,570
	Ending balance	$	20,551			$	(2,310	)	$	(53,652	)	$	(35,411	)
		Three months ended March 31, 2014
		Unrealized gains (losses) on available for sale securities1				Gains (losses) on cash flow hedges1			Defined benefit pension items1			Total
	Beginning balance	$	(10,091	)		$	(4,434	)	$	(10,743	)	$	(25,268	)
	Other comprehensive income before reclassifications	7,256				441			—			7,697
	Amounts reclassified from accumulated other comprehensive (loss) income	—				—			977			977
	Net current period other comprehensive income	7,256				441			977			8,674
	Ending balance	$	(2,835	)		$	(3,993	)	$	(9,766	)	$	(16,594	)
	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, 2015 and March 31, 2014:
	(Dollars in thousands)		Three months ended March 31, 2015
	Details about accumulated other comprehensive loss		Amount reclassified from accumulated other comprehensive (loss) income1				Affected line item in the statement where net income is presented
	Unrealized gains and losses on available for sale securities
			$	5,126			Securities gains
			(1,977		)		Income taxes
			$	3,149			Net income
	Amortization of defined benefit pension items
	Prior service costs		$	(53	)		Employee benefits
	Actuarial losses		(2,833		)		Employee benefits
			(2,886		)		Income before income taxes
			1,123				Provision for income taxes
			$	(1,763	)		Net income
	Total reclassifications for the period		$	1,386
			Three months ended March 31, 2014
	Details about accumulated other comprehensive loss		Amount reclassified from accumulated other comprehensive (loss) income1				Affected line item in the statement where net income is presented
	Amortization of defined benefit pension items
	Prior service costs		$	(53	)		Employee benefits
	Actuarial losses		(1,546		)		Employee benefits
			(1,599		)		Income before income taxes
			622				Provision for income taxes
			$	(977	)		Net income
	Total reclassifications for the period		$	(977	)
	1 Amounts in parentheses indicate debits to profit/loss.

Repurchase_Agreements_Repurcha

Repurchase Agreements Repurchase Agreements	3 Months Ended
	Mar. 31, 2015
Repurchase Agreements [Abstract]
Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block]	NOTE I - REPURCHASE AGREEMENTS
	We utilize securities sold under agreements to repurchase to facilitate the needs of our customers and secure long-term funding needs. Repurchase agreements are transactions whereby we offer 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 reflected as short-term borrowings on the Consolidated Balance Sheets.
	We monitor collateral levels on a continuous basis and maintain records of each transaction specifically describing the applicable security and the counterparty’s fractional interest in that security, and we segregate the security from its general assets in accordance with regulations governing custodial holdings of securities. The primary risk with our repurchase agreements is market risk associated with the securities securing the transactions, as we may be required to provide additional collateral based on fair value changes of the underlying securities. Securities pledged as collateral under repurchase agreements are maintained with our safekeeping agents. The carrying value of investment securities available for sale pledged as collateral under repurchase agreements totaled $386.8 million and $418.3 million at March 31, 2015 and December 31, 2014.
	The remaining contractual maturity of the securities sold under agreements to repurchase by class of collateral pledged included in short-term borrowings in the Consolidated Balance Sheets as of March 31, 2015 and December 31, 2014 is presented in the following tables.
		March 31, 2015
		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	$	335,283	$	—	$	—	$	23,091	$	358,374
	Government agency	—		—		—		6,909		6,909
	Total borrowings	$	335,283	$	—	$	—	$	30,000	$	365,283
	Gross amount of recognized liabilities for repurchase agreements									$	365,283
		December 31, 2014
		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	$	162,924	$	—	$	—	$	23,086	$	186,010
	Government agency	—		—		—		6,914		6,914
	Mortgage-backed securities	131,501		—		—		—		131,501
	Total borrowings	$	294,425	$	—	$	—	$	30,000	$	324,425
	Gross amount of recognized liabilities for repurchase agreements									$	324,425

Mortgage_Servicing_Rights_Mort

Mortgage Servicing Rights Mortgage Servicing Rights (Notes)	3 Months Ended
	Mar. 31, 2015
Mortgage Servicing Rights [Abstract]
Transfers and Servicing of Financial Assets [Text Block]	NOTE H - MORTGAGE SERVICING RIGHTS
	The activity of the servicing asset for first quarter 2015 and 2014 is presented in the following table:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Balance at January 1	$	16,688		$	16
	Servicing rights originated	662			—
	Amortization	(852		)	(164		)
	Servicing rights acquired in the 1st Financial merger	—			148
	Valuation allowance provision	$	(62	)	$	—
	Balance at March 31	$	16,436		$	—
	The following table presents the activity in the servicing asset valuation allowance for first quarter 2015 and 2014:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Balance at January 1	$	850		$	—
	Valuation allowance provision	62			—
	Balance at March 31	$	912		$	—
	As of March 31, 2015, the carrying value of BancShares' mortgage servicing rights was $16.4 million. Contractually specified mortgage servicing fees, late fees, and ancillary fees earned for the three months ended March 31, 2015 were $1.1 million and is included in mortgage income in the Consolidated Statements of Income. There were no mortgage servicing fees, late fees or ancillary fees earned for the three months ended March 31, 2014.
	The amortization expense related to mortgage servicing rights, included as a reduction of mortgage income in the Consolidated Statements of Income, was $852 thousand and $164 thousand for the three months ended March 31, 2015 and March 31, 2014, respectively. Amortization expense included impairment of $62 thousand for the three months ended March 31, 2015. There was no impairment recorded for the three months ended March 31, 2014.
	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, 2015 and December 31, 2014 were as follows:
		March 31, 2015			December 31, 2014
	Discount rate - conventional fixed loans	6.95		%	7.2		%
	Discount rate - all loans excluding conventional fixed loans	8.95		%	9.2		%
	Weighted average constant prepayment rate	16.07		%	14.25		%
	Weighted average cost to service loans	$	56.02		$	56.02

Accounting_Policies_and_Basis_1

Accounting Policies and Basis of Presentation Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Reclassification, Policy [Policy Text Block]	Reclassifications
	Prior period financial statements reflect the retrospective application of Accounting Standards Update ("ASU") 2014-01, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments Qualified Affordable Housing Projects which was adopted effective in the fourth quarter of 2014 and did not have a material impact on our consolidated financial condition or results of operations. In certain instances other than the retrospective adoption of ASU 2014-01, 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 shareholders' equity or net income.
Use of Estimates, Policy [Policy Text Block]	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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. 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
	•	Receivable from and payable to the FDIC for loss share agreements
	•	Income tax assets, liabilities and expense
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements
	FASB ASU 2015-03, Interest–Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs
	This ASU simplifies the presentation of debt issuance costs by requiring that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liability, consistent with debt discounts or premiums. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update.
	This ASU is effective for interim and annual periods beginning after December 15, 2015 for public companies, and is to be applied retrospectively. Early adoption is permitted. We will adopt the guidance effective in the first quarter of 2016.
	FASB ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis
	This ASU improves targeted areas of consolidation guidance for reporting organizations that are required to evaluate whether they should consolidate certain legal entities. In addition to reducing the number of consolidation models from four to two, the new standard places more emphasis on risk of loss when determining a controlling financial interest, reducing the frequency of the application of related-party guidance when determining a controlling financial interest in a variable interest entity ("VIE"), and changing consolidation conclusions for public and private companies in several industries that typically make use of limited partnerships or VIEs.
	The amendments in this ASU are effective for periods beginning after December 15, 2015 for public companies. Early adoption is permitted. We will adopt the guidance effective in the first quarter of 2016 and do not anticipate any significant impact on our consolidated financial position or consolidated results of operations as a result of adoption.
	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 companies 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 also results in enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively and improves guidance for multiple-element arrangements.
	The guidance in this ASU is effective for fiscal periods beginning after December 15, 2016, including interim reporting periods within that reporting period. Early adoption is not permitted. We are currently evaluating the impact of the new standard and we will adopt during the first quarter of 2017 using one of two retrospective application methods.

Business_Combinations_Tables

Business Combinations (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Pro Forma Financial Information for Bancorporation Acquisition
		Three months ended March 31
	(Dollars in thousands)	2014
	Total revenue (interest income plus noninterest income)	$	323,524
	Net income	$	37,230

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Investments [Abstract]
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, 2015 and December 31, 2014, are as follows:
		March 31, 2015
	(Dollars in thousands)	Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	Investment securities available for sale
	U.S. Treasury	$	2,237,002		$	9,966	$	2	$	2,246,966
	Government agency	988,563			2,382		51		990,894
	Mortgage-backed securities	3,785,912			27,006		5,669		3,807,249
	Total investment securities available for sale	$	7,011,477		$	39,354	$	5,722	$	7,045,109
		December 31, 2014
		Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	U.S. Treasury	$	2,626,900		$	2,922	$	152	$	2,629,670
	Government agency	908,362			702		247		908,817
	Mortgage-backed securities	3,628,187			16,964		11,847		3,633,304
	Municipal securities	125			1		—		126
	Total investment securities available for sale	$	7,163,574		$	20,589	$	12,246	$	7,171,917
		March 31, 2015
		Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	Investment securities held to maturity
	Mortgage-backed securities	$	441		$	18	$	—	$	459
		December 31, 2014
		Cost			Gross		Gross unrealized		Fair
					unrealized		losses		value
					gains
	Mortgage-backed securities	$	518		$	26	$	—	$	544
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, 2015					December 31, 2014
	(Dollars in thousands)	Cost			Fair		Cost		Fair
					value				value
	Investment securities available for sale
	Non-amortizing securities maturing in:
	One year or less	$	504,826		$	505,182	$	447,866	$	447,992
	One through five years	2,720,739			2,732,678		3,087,521		3,090,621
	Mortgage-backed securities	3,785,912			3,807,249		3,628,187		3,633,304
	Total investment securities available for sale	$	7,011,477		$	7,045,109	$	7,163,574	$	7,171,917
	Investment securities held to maturity
	Mortgage-backed securities held to maturity	$	441		$	459	$	518	$	544
Securities Gains (Losses)	For each period presented, securities gains (losses) included the following:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Gross gains on sales of investment securities available for sale	$	5,135		$	—
	Gross losses on sales of investment securities available for sale	(9		)	—
	Total securities gains	$	5,126		$	—
Investment Securities With Unrealized Losses	The following table provides information regarding securities with unrealized losses as of March 31, 2015 and December 31, 2014.
		March 31, 2015
		Less than 12 months					12 months or more				Total
	(Dollars in thousands)	Fair			Unrealized		Fair		Unrealized		Fair		Unrealized
		value			losses		value		losses		value		losses
	Investment securities available for sale:
	U.S. Treasury	$	13,024		$	2	$	—	$	—	$	13,024	$	2
	Government agency	69,660			51		—		—		69,660		51
	Mortgage-backed securities	562,616			1,645		317,685		4,024		880,301		5,669
	Total	$	645,300		$	1,698	$	317,685	$	4,024	$	962,985	$	5,722
		December 31, 2014
		Less than 12 months					12 months or more				Total
		Fair			Unrealized		Fair		Unrealized		Fair		Unrealized
		value			losses		value		losses		value		losses
	Investment securities available for sale:
	U.S. Treasury	$	338,612		$	151	$	1,015	$	1	$	339,627	$	152
	Government agency	261,288			247		—		—		261,288		247
	Mortgage-backed securities	573,374			1,805		831,405		10,042		1,404,779		11,847
	Total	$	1,173,274		$	2,203	$	832,420	$	10,043	$	2,005,694	$	12,246

Loans_and_Leases_Tables

Loans and Leases (Tables)	3 Months Ended
	Mar. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Loans And Leases Outstanding	Loans and leases outstanding include the following at March 31, 2015 and December 31, 2014:
	(Dollars in thousands)	March 31, 2015			December 31, 2014
	Non-PCI loans and leases:
	Commercial:
	Construction and land development	$	608,556		$	550,568
	Commercial mortgage	7,591,745			7,552,948
	Other commercial real estate	262,293			244,875
	Commercial and industrial	2,072,414			1,988,934
	Lease financing	603,737			571,916
	Other	354,713			353,833
	Total commercial loans	11,493,458			11,263,074
	Noncommercial:
	Residential mortgage	2,524,549			2,520,542
	Revolving mortgage	2,528,257			2,561,800
	Construction and land development	170,208			120,097
	Consumer	1,127,942			1,117,454
	Total noncommercial loans	6,350,956			6,319,893
	Total non-PCI loans and leases	17,844,414			17,582,967
	PCI loans:
	Commercial:
	Construction and land development	70,049			78,079
	Commercial mortgage	653,846			577,518
	Other commercial real estate	40,841			40,193
	Commercial and industrial	24,134			27,254
	Other	2,886			3,079
	Total commercial loans	791,756			726,123
	Noncommercial:
	Residential mortgage	380,490			382,340
	Revolving mortgage	70,363			74,109
	Construction and land development	874			912
	Consumer	3,860			3,014
	Total noncommercial loans	455,587			460,375
	Total PCI loans	1,247,343			1,186,498
	Total loans and leases	$	19,091,757		$	18,769,465
Composition Of The Loans And Leases Outstanding By Credit Quality Indicator	Non-PCI loans and leases outstanding at March 31, 2015 and December 31, 2014 by credit quality indicator are provided below:
		March 31, 2015
	(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
		development			mortgage			commercial real estate		industrial
	Pass	$	590,298		$	7,341,243		$	260,592	$	1,931,078	$	597,464	$	350,060	$	11,070,735
	Special mention	15,679			115,411			501		21,771		2,609		1,913		157,884
	Substandard	2,291			131,672			1,049		8,806		3,284		2,690		149,792
	Doubtful	—			2,039			—		4,402		329		—		6,770
	Ungraded	288			1,380			151		106,357		51		50		108,277
	Total	$	608,556		$	7,591,745		$	262,293	$	2,072,414	$	603,737	$	354,713	$	11,493,458
		December 31, 2014
		Non-PCI commercial loans and leases
		Construction  and land			Commercial			Other		Commercial  and		Lease financing		Other		Total non-PCI commercial loans and leases
		development			mortgage			commercial real estate		industrial
	Pass	$	525,711		$	7,284,714		$	242,053	$	1,859,415	$	564,319	$	349,111	$	10,825,323
	Special mention	20,025			129,247			909		27,683		3,205		1,384		182,453
	Substandard	4,720			134,677			1,765		8,878		3,955		3,338		157,333
	Doubtful	—			2,366			—		164		365		—		2,895
	Ungraded	112			1,944			148		92,794		72		—		95,070
	Total	$	550,568		$	7,552,948		$	244,875	$	1,988,934	$	571,916	$	353,833	$	11,263,074
		March 31, 2015
		Non-PCI noncommercial loans and leases
	(Dollars in thousands)	Residential			Revolving			Construction		Consumer		Total non-PCI noncommercial
		mortgage			mortgage			and land				loans and leases
								development
	Current	$	2,490,453		$	2,510,879		$	168,199	$	1,121,123	$	6,290,654
	30-59 days past due	21,844			10,288			2,009		4,236		38,377
	60-89 days past due	2,896			2,794			—		1,555		7,245
	90 days or greater past due	9,356			4,296			—		1,028		14,680
	Total	$	2,524,549		$	2,528,257		$	170,208	$	1,127,942	$	6,350,956
		December 31, 2014
		Non-PCI noncommercial loans and leases
		Residential			Revolving			Construction		Consumer		Total non-PCI noncommercial
		mortgage			mortgage			and land				loans and leases
								development
	Current	$	2,482,281		$	2,542,807		$	119,094	$	1,110,153	$	6,254,335
	30-59 days past due	23,288			11,097			370		4,577		39,332
	60-89 days past due	6,018			2,433			486		1,619		10,556
	90 days or greater past due	8,955			5,463			147		1,105		15,670
	Total	$	2,520,542		$	2,561,800		$	120,097	$	1,117,454	$	6,319,893
	PCI loans and leases outstanding at March 31, 2015 and December 31, 2014 by credit quality indicator are provided below:
		March 31, 2015
	(Dollars in thousands)	PCI commercial loans
	Grade:	Construction			Commercial			Other		Commercial		Other		Total PCI commercial
		and land			mortgage			commercial		and				loans
		development						real estate		industrial
	Pass	$	13,832		$	333,368		$	9,727	$	13,525	$	683	$	371,135
	Special mention	4,287			118,209			16,425		2,963		—		141,884
	Substandard	44,663			193,435			12,948		6,739		2,132		259,917
	Doubtful	4,656			8,456			1,741		513		71		15,437
	Ungraded	2,611			378			—		394		—		3,383
	Total	$	70,049		$	653,846		$	40,841	$	24,134	$	2,886	$	791,756
		December 31, 2014
		PCI commercial loans
		Construction			Commercial			Other		Commercial		Other		Total PCI commercial
		and land			mortgage			commercial		and				loans
		development						real estate		industrial
	Pass	$	13,514		$	300,187		$	11,033	$	16,637	$	801	$	342,172
	Special mention	6,063			98,724			16,271		4,137		—		125,195
	Substandard	53,739			171,920			12,889		6,312		2,278		247,138
	Doubtful	2,809			6,302			—		130		—		9,241
	Ungraded	1,954			385			—		38		—		2,377
	Total	$	78,079		$	577,518		$	40,193	$	27,254	$	3,079	$	726,123
	March 31, 2015
	PCI noncommercial loans
(Dollars in thousands)	Residential			Revolving			Construction		Consumer		Total PCI noncommercial
	mortgage			mortgage			and land				loans
							development
Current	$	320,607		$	63,579		$	592	$	3,571	$	388,349
30-59 days past due	18,742			2,800			—		130		21,672
60-89 days past due	6,804			1,019			—		13		7,836
90 days or greater past due	34,337			2,965			282		146		37,730
Total	$	380,490		$	70,363		$	874	$	3,860	$	455,587
	December 31, 2014
	PCI noncommercial loans
	Residential			Revolving			Construction		Consumer		Total PCI noncommercial
	mortgage			mortgage			and land				loans
							development
Current	$	326,589		$	68,548		$	506	$	2,582	$	398,225
30-59 days past due	11,432			1,405			—		147		12,984
60-89 days past due	10,073			345			—		25		10,443
90 days or greater past due	34,246			3,811			406		260		38,723
Total	$	382,340		$	74,109		$	912	$	3,014	$	460,375
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, 2015 and December 31, 2014 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, 2015
	(Dollars in thousands)	30-59 days			60-89 days			90 days or greater		Total past		Current		Total loans
		past due			past due					due				and leases
	Non-PCI loans and leases:
	Construction and land development - commercial	$	2,709		$	712		$	1,044	$	4,465	$	604,091	$	608,556
	Commercial mortgage	22,635			5,920			8,445		37,000		7,554,745		7,591,745
	Other commercial real estate	583			58			196		837		261,456		262,293
	Commercial and industrial	6,290			1,724			570		8,584		2,063,830		2,072,414
	Lease financing	476			11			—		487		603,250		603,737
	Residential mortgage	21,844			2,896			9,356		34,096		2,490,453		2,524,549
	Revolving mortgage	10,288			2,794			4,296		17,378		2,510,879		2,528,257
	Construction and land development - noncommercial	2,009			—			—		2,009		168,199		170,208
	Consumer	4,236			1,555			1,028		6,819		1,121,123		1,127,942
	Other	380			65			133		578		354,135		354,713
	Total non-PCI loans and leases	$	71,450		$	15,735		$	25,068	$	112,253	$	17,732,161	$	17,844,414
		December 31, 2014
		30-59 days			60-89 days			90 days or greater		Total past		Current		Total loans
		past due			past due					due				and leases
	Non-PCI loans and leases:
	Construction and land development - commercial	$	1,796		$	621		$	385	$	2,802	$	547,766	$	550,568
	Commercial mortgage	11,367			4,782			8,061		24,210		7,528,738		7,552,948
	Other commercial real estate	206			70			102		378		244,497		244,875
	Commercial and industrial	2,843			1,545			378		4,766		1,984,168		1,988,934
	Lease financing	1,631			8			2		1,641		570,275		571,916
	Residential mortgage	23,288			6,018			8,955		38,261		2,482,281		2,520,542
	Revolving mortgage	11,097			2,433			5,463		18,993		2,542,807		2,561,800
	Construction and land development - noncommercial	370			486			147		1,003		119,094		120,097
	Consumer	4,577			1,619			1,105		7,301		1,110,153		1,117,454
	Other	146			1,966			—		2,112		351,721		353,833
	Total non-PCI loans and leases	$	57,321		$	19,548		$	24,598	$	101,467	$	17,481,500	$	17,582,967
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, 2015 and December 31, 2014 for non-PCI loans, were as follows:
		March 31, 2015						December 31, 2014
	(Dollars in thousands)	Nonaccrual			Loans and			Nonaccrual		Loans and
		loans and			leases > 90			loans and		leases > 90
		leases			days and			leases		days and
					accruing					accruing
	Non-PCI loans and leases:
	Construction and land development - commercial	$	1,497		$	202		$	343	$	111
	Commercial mortgage	26,058			764			24,720		1,003
	Other commercial real estate	650			—			619		35
	Commercial and industrial	5,691			294			1,741		239
	Lease financing	346			—			374		2
	Residential mortgage	19,238			1,153			14,242		3,191
	Revolving mortgage	9,837			19			—		5,463
	Construction and land development - noncommercial	—			—			—		147
	Consumer	677			626			—		1,059
	Other	2,052			31			1,966		—
	Total non-PCI loans and leases	$	66,046		$	3,089		$	44,005	$	11,250
Changes In Carrying Value Of PCI Loans	The recorded fair values of PCI loans acquired in the CCBT acquisition as of the acquisition date are as follows:
	(Dollars in thousands)
	Commercial:
	Construction and land development	$	4,221
	Commercial mortgage	125,202
	Other commercial real estate	3,132
	Commercial and industrial	3,049
	Total commercial loans	135,604
	Noncommercial:
	Residential mortgage	12,050
	Consumer	1,640
	Total noncommercial loans	13,690
	Total PCI loans and leases	$	149,294
	The following table provides changes in the carrying value of all purchased credit-impaired loans during the three months ended March 31, 2015 and March 31, 2014:
	(Dollars in thousands)	2015			2014
	Balance at January 1	$	1,186,498		$	1,029,426
	Fair value of acquired loans	149,294			316,327
	Accretion	25,067			30,200
	Payments received and other changes, net	(113,516		)	(105,135		)
	Balance at March 31	$	1,247,343		$	1,270,818
	Unpaid principal balance at March 31	$	2,092,936		$	1,727,492
Schedule of Contractually Required Payments Including Principal and Interest Expected Cash Flows to be Collected and Fair Values [Table Text Block]	The following table relates to PCI loans acquired in the CCBT acquisition and summarizes the contractually required payments, which include principal and interest, expected cash flows to be collected, and the fair value of PCI loans and leases at the acquisition date.
	(Dollars in thousands)
	Contractually required payments	$	251,800
	Cash flows expected to be collected	$	204,480
	Fair value of loans at acquisition	$	149,294
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 2015 and 2014.
	(Dollars in thousands)	2015			2014
	Balance at January 1	$	418,160		$	439,990
	Additions from acquisitions	55,186			84,295
	Accretion	(25,067		)	(30,200		)
	Reclassifications from nonaccretable difference	1,294			6,048
	Changes in expected cash flows that do not affect nonaccretable difference	(27,287		)	(9,888		)
	Balance at March 31	$	422,286		$	490,245

Allowance_for_Loan_and_Lease_L1

Allowance for Loan and Lease Losses (Tables)	3 Months Ended
	Mar. 31, 2015
Allowance for Loan and Lease Losses, Adjustments, Net [Abstract]
Allowance for Loan and Lease Losses	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, 2015 and March 31, 2014:
		Three months ended March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other commercial real estate			Commercial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage						and industrial				financing						mortgage			mortgage			and land
		development																										development
		- commercial																										- non-
																												commercial
	Non-PCI Loans
	Allowance for loan and lease losses:
	Balance at January 1	$	11,961			$	85,189		$	732		$	30,727			$	4,286		$	3,184		$	10,661		$	18,650		$	892		$	16,555		$	182,837
	Provision	1,103				(3,679		)	458			7,546				11			(218		)	813			(462		)	118			2,966			8,656
	Charge-offs	(18		)		(233		)	(169		)	(1,713		)		(15		)	—			(284		)	(793		)	(22		)	(2,783		)	(6,030		)
	Recoveries	62				761			10			394				11			15			138			134			68			878			2,471
	Balance at March 31	$	13,108			$	82,038		$	1,031		$	36,954			$	4,293		$	2,981		$	11,328		$	17,529		$	1,056		$	17,616		$	187,934
		Three months ended March 31, 2014
		Construction				Commercial			Other commercial real estate			Commercial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage						and industrial				financing						mortgage			mortgage			and land
		development																										development
		- commercial																										- non-
																												commercial
	Balance at January 1	$	10,335			$	100,257		$	1,009		$	22,362			$	4,749		$	190		$	10,511		$	16,239		$	681		$	13,541		$	179,874
	Provision	1,885				(6,979		)	(74		)	1,976				(524		)	272			609			1,353			577			1,275			370
	Charge-offs	—				(168		)	—			(496		)		(58		)	(8		)	(184		)	(1,260		)	(71		)	(2,177		)	(4,422		)
	Recoveries	26				1,107			10			179				16			—			8			76			62			643			2,127
	Balance at March 31	$	12,246			$	94,217		$	945		$	24,021			$	4,183		$	454		$	10,944		$	16,408		$	1,249		$	13,282		$	177,949
	The following tables show the activity in the allowance for PCI loan and lease losses by loan class for the three months ended March 31, 2015 and March 31, 2014.
		Three months ended March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
		development -							real estate			industrial										development -
		commercial																				noncommercial
	PCI Loans
	Allowance for loan and lease losses:
	Balance at January 1	$	150			$	10,135		$	75		$	1,240			$	5,820		$	3,999		$	183		$	27		$	21,629
	Provision	191				(925		)	119			(1,031		)		(863		)	(655		)	(152		)	452			(2,864		)
	Charge-offs	—				(334		)	—			(198		)		(85		)	(73		)	—			(456		)	(1,146		)
	Recoveries	—				—			—			—				—			—			—			—			—
	Balance at March 31	$	341			$	8,876		$	194		$	11			$	4,872		$	3,271		$	31		$	23		$	17,619
		Three months ended March 31, 2014
	(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
		development -							real estate			industrial										development -
		commercial																				noncommercial
	Balance at January 1	$	1,320			$	29,906		$	1,354		$	5,275			$	11,802		$	2,959		$	682		$	222		$	53,520
	Provision	3,355				(3,386		)	(150		)	(336		)		(2,300		)	634			(99		)	9			(2,273		)
	Charge-offs	(199		)		(3,517		)	—			(2,683		)		262			(100		)	—			(17		)	(6,254		)
	Recoveries	—				—			—			—				—			—			—			—			—
	Balance at March 31	$	4,476			$	23,003		$	1,204		$	2,256			$	9,764		$	3,493		$	583		$	214		$	44,993
	The following tables provide information on non-PCI impaired loans and leases, exclusive of loans and leases evaluated collectively as a homogenous group, as of March 31, 2015 and December 31, 2014 including interest income recognized in the period during which the loans and leases were considered impaired.
		March 31, 2015
	(Dollars in thousands)	With a				With no			Total			Unpaid				Related
		recorded				recorded						principal				allowance
		allowance				allowance						balance				recorded
	Non-PCI impaired loans and leases:
	Construction and land development - commercial	$	2,114			$	858		$	2,972		$	4,228			$	182
	Commercial mortgage	53,220				24,071			77,291			81,826				7,494
	Other commercial real estate	104				439			543			847				104
	Commercial and industrial	13,123				846			13,969			14,939				2,809
	Lease financing	1,221				271			1,492			1,492				236
	Other	1,977				—			1,977			1,977				1,955
	Residential mortgage	8,662				6,533			15,195			15,852				1,177
	Revolving mortgage	1,439				1,483			2,922			3,925				108
	Construction and land development - noncommercial	733				—			733			733				90
	Consumer	904				80			984			1,004				531
Total non-PCI impaired loans and leases	$	83,497			$	34,581		$	118,078		$	126,823			$	14,686
	December 31, 2014
(Dollars in thousands)	With a				With no			Total			Unpaid				Related
	recorded				recorded						principal				allowance
	allowance				allowance						balance				recorded
Non-PCI impaired loans and leases:
Construction and land development - commercial	$	996			$	624		$	1,620		$	6,945			$	92
Commercial mortgage	57,324				25,479			82,803			87,702				8,610
Other commercial real estate	112				472			584			913				112
Commercial and industrial	10,319				721			11,040			12,197				1,743
Lease financing	319				304			623			623				150
Other	2,000				—			2,000			2,000				1,972
Residential mortgage	10,198				4,715			14,913			15,746				1,360
Revolving mortgage	3,675				—			3,675			4,933				1,052
Construction and land development - noncommercial	1,077				263			1,340			1,340				71
Consumer	987				8			995			1,067				555
Total non-PCI impaired loans and leases	$	87,007			$	32,586		$	119,593		$	133,466			$	15,717
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, 2015 and March 31, 2014:
	Three months ended March 31, 2015							Three months ended March 31, 2014
(Dollars in thousands)	Average				Interest income recognized			Average			Interest income recognized
	balance							balance
Non-PCI impaired loans and leases:
Construction and land development - commercial	$	3,052			$	35		$	1,031		$	15
Commercial mortgage	80,553				769			94,547			1,120
Other commercial real estate	551				1			1,796			21
Commercial and industrial	14,229				103			10,234			118
Lease financing	1,590				18			284			4
Other	1,990				—			—			—
Residential mortgage	15,364				125			16,482			174
Revolving mortgage	2,986				16			3,892			27
Construction and land development - noncommercial	658				7			2,322			29
Consumer	1,022				19			1,059			5
Total non-PCI impaired loans and leases	$	121,995			$	1,093		$	131,647		$	1,513
Allocation of Allowance for Loan and Lease Losses	The following tables show the ending balances of PCI loans and leases and related allowance by class of loans as of March 31, 2015 and December 31, 2014:
		March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
		development -							real estate			industrial										development -
		commercial																				noncommercial
	ALLL for loans and leases acquired with deteriorated credit quality	$	341			$	8,876		$	194		$	11			$	4,872		$	3,271		$	31		$	23		$	17,619
	Loans and leases acquired with deteriorated credit quality	70,049				653,846			40,841			24,134				380,490			70,363			874			6,746			1,247,343
		December 31, 2014
	(Dollars in thousands)	Construction				Commercial			Other			Commercial				Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial			and				mortgage			mortgage			and land			and other
		development -							real estate			industrial										development -
		commercial																				noncommercial
	ALLL for loans and leases acquired with deteriorated credit quality	$	150			$	10,135		$	75		$	1,240			$	5,820		$	3,999		$	183		$	27		$	21,629
	Loans and leases acquired with deteriorated credit quality	78,079				577,518			40,193			27,254				382,339			74,109			912			6,094			1,186,498
	The following tables present the allowance for non-PCI loan losses and the recorded investment in loans, by loan class, based on impairment method as of March 31, 2015 and December 31, 2014:
		March 31, 2015
	(Dollars in thousands)	Construction				Commercial			Other			Commercial and industrial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial							financing						mortgage			mortgage			and land
		development							real estate																			development
		- commercial																										- non-commercial
	Allowance for loan and lease losses:
	ALLL for loans and leases individually evaluated for impairment	$	182			$	7,494		$	104		$	2,809			$	236		$	1,955		$	1,177		$	108		$	90		$	531		$	14,686
	ALLL for loans and leases collectively evaluated for impairment	12,926				74,544			927			34,145				4,057			1,026			10,151			17,421			966			17,085			173,248
	Total allowance for loan and lease losses	$	13,108			$	82,038		$	1,031		$	36,954			$	4,293		$	2,981		$	11,328		$	17,529		$	1,056		$	17,616		$	187,934
	Loans and leases:
	Loans and leases individually evaluated for impairment	$	2,972			$	77,291		$	543		$	13,969			$	1,492		$	1,977		$	15,195		$	2,922		$	733		$	984		$	118,078
	Loans and leases collectively evaluated for impairment	605,584				7,514,454			261,750			2,058,445				602,245			352,736			2,509,354			2,525,335			169,475			1,126,958			17,726,336
	Total loan and leases	$	608,556			$	7,591,745		$	262,293		$	2,072,414			$	603,737		$	354,713		$	2,524,549		$	2,528,257		$	170,208		$	1,127,942		$	17,844,414
		December 31, 2014
	(Dollars in thousands)	Construction				Commercial			Other			Commercial and industrial				Lease			Other			Residential			Revolving			Construction			Consumer			Total
		and land				mortgage			commercial							financing						mortgage			mortgage			and land
		development							real estate																			development
		- commercial																										- non-commercial
	Allowance for loan and lease losses:
	ALLL for loans and leases individually evaluated for impairment	$	92			$	8,610		$	112		$	1,743			$	150		$	1,972		$	1,360		$	1,052		$	71		$	555		$	15,717
	ALLL for loans and leases collectively evaluated for impairment	11,869				76,579			620			28,984				4,136			1,212			9,301			17,598			821			16,000			167,120
	Total allowance for loan and lease losses	$	11,961			$	85,189		$	732		$	30,727			$	4,286		$	3,184		$	10,661		$	18,650		$	892		$	16,555		$	182,837
	Loans and leases:
	Loans and leases individually evaluated for impairment	$	1,620			$	82,803		$	584		$	11,040			$	623		$	2,000		$	14,913		$	3,675		$	1,340		$	995		$	119,593
	Loans and leases collectively evaluated for impairment	548,948				7,470,145			244,291			1,977,894				571,293			351,833			2,505,629			2,558,125			118,757			1,116,459			17,463,374
	Total loan and leases	$	550,568			$	7,552,948		$	244,875		$	1,988,934			$	571,916		$	353,833		$	2,520,542		$	2,561,800		$	120,097		$	1,117,454		$	17,582,967
Troubled Debt Restructurings on Financing Receivables
		Three months ended March 31, 2015										Three months ended March 31, 2014
		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
	Interest only period provided
	Commercial mortgage	—		$	—			—	$	—		4		$	1,911			2	$	410
	Commercial and industrial	1		3,796				1	3,796			1		196				—	—
	Lease financing	—		—				—	—			2		146				—	—
	Total interest only	1		3,796				1	3,796			7		2,253				2	410
	Loan term extension
	Construction and land development - commercial	1		220				1	220			—		—				—	—
	Commercial mortgage	3		535				—	—			5		2,620				—	—
	Lease financing	—		—				—	—			2		234				—	—
	Revolving mortgage	1		10				—	—			—		—				—	—
	Residential mortgage	—		—				—	—			5		338				—	—
	Consumer	1		5				—	—			—		—				1	41
	Total loan term extension	6		770				1	220			12		3,192				1	41
	Below market interest rate
	Construction and land development - commercial	2		47				—	—			1		82				—	—
	Commercial mortgage	9		3,541				2	733			12		4,677				1	449
	Commercial and industrial	3		172				—	—			2		110				—	—
	Residential mortgage	23		708				2	45			8		451				3	127
	Revolving mortgage	2		18				—	—			5		278				—	—
	Construction and land development - noncommercial	2		396				—	—			—		—				—	—
	Consumer	3		34				—	—			—		—				—	—
	Other	1		1,950				—	—			—		—				—	—
	Total below market interest rate	45		6,866				4	778			28		5,598				4	576
	Discharged from bankruptcy
	Commercial mortgage	—		—				—	—			1		1,003				—	—
	Residential mortgage	2		68				—	—			7		708				2	288
	Revolving mortgage	5		218				2	147			4		229				—	—
	Construction and land development-noncommercial	—		—				—	—			1		62				—	—
	Consumer	—		—				—	—			1		18				—	—
	Total discharged from bankruptcy	7		286				2	147			14		2,020				2	288
	Total non-PCI restructurings	59		$	11,718			8	$	4,941		61		$	13,063			9	$	1,315
		Three months ended March 31, 2015										Three months ended March 31, 2014
		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 mortgage	—		$	—			—	$	—		2		$	15,906			2	$	15,906
	Total interest only	—		—				—	—			2		15,906				2	15,906
	Loan term extension
	Construction and land development - commercial	—		—				—	—			1		281				—	—
	Total loan term extension	—		—				—	—			1		281				—	—
	Below market interest rate
	Construction and land development - commercial	—		—				—	—			1		37				—	—
	Commercial mortgage	—		—				—	—			4		5,439				1	47
	Commercial and industrial	—		—				1	65			—		—				—	—
	Residential mortgage	7		470				—	—			1		102				1	436
	Total below market interest rate	7		470				1	65			6		5,578				2	31,812
	Total PCI restructurings	7		$	470			1	$	65		9		$	21,765			4	$	47,718
	The following table provides a summary of total TDRs by accrual status.
		March 31, 2015										December 31, 2014
	(Dollars in thousands)	Accruing				Nonaccruing			Total			Accruing				Nonaccruing			Total
	Commercial loans
	Construction and land development -	$	3,425			$	490		$	3,915		$	2,591			$	446		$	3,037
	commercial
	Commercial mortgage	88,889				11,326			100,215			92,184				8,937			101,121
	Other commercial real estate	2,123				423			2,546			2,374				449			2,823
	Commercial and industrial	9,248				4,768			14,016			9,864				664			10,528
	Lease	1,163				329			1,492			258				365			623
	Other	—				—			—			34				—			34
Total commercial TDRs	104,848				17,336			122,184			107,305				10,861			118,166
Noncommercial
Residential	23,060				5,097			28,157			22,597				4,655			27,252
Revolving mortgage	1,871				1,112			2,983			3,675				—			3,675
Construction and land development -	733				—			733			1,391				—			1,391
noncommercial
Consumer and other	954				1,980			2,934			995				—			995
Total noncommercial TDRs	26,618				8,189			34,807			28,658				4,655			33,313
Total TDRs	$	131,466			$	25,525		$	156,991		$	135,963			$	15,516		$	151,479
The majority of TDRs are included in the special mention, substandard or doubtful grading categories, which results in more elevated loss expectations when determining 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, TDRs over $500,000 and graded substandard or lower are evaluated individually for impairment through a review of collateral values.
The following table shows the accrual status of non-PCI and PCI TDRs.
(Dollars in thousands)	March 31, 2015				December 31, 2014
Accruing TDRs:
PCI	$	44,582			$	44,647
Non-PCI	86,884				91,316
Total accruing TDRs	131,466				135,963
Nonaccruing TDRs:
PCI	1,999				2,225
Non-PCI	23,526				13,291
Total nonaccruing TDRs	25,525				15,516
All TDRs:
PCI	46,581				46,872
Non-PCI	110,410				104,607
Total TDRs	$	156,991			$	151,479

Other_Real_Estate_Owned_Tables

Other Real Estate Owned (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015 and March 31, 2014.
	(Dollars in thousands)	Covered			Noncovered			Total
	Balance at December 31, 2013	$	47,081		$	36,898		$	83,979
	Additions	1,514			3,318			4,832
	Additions acquired in the 1st Financial merger	—			11,591			11,591
	Sales	(4,512		)	(5,854		)	(10,366		)
	Writedowns	(2,228		)	(1,449		)	(3,677		)
	Balance at March 31, 2014	$	41,855		$	44,504		$	86,359
	Balance at December 31, 2014	$	22,982		$	70,454		$	93,436
	Additions	4,244			17,084			21,328
	Sales	(8,970		)	(13,573		)	(22,543		)
	Writedowns	(954		)	(1,275		)	(2,229		)
	Balance at March 31, 2015	$	17,302		$	72,690		$	89,992
	At March 31, 2015 and December 31, 2014, BancShares had $23.2 million and $29.0 million, respectively, of foreclosed residential real estate property in OREO and $20.1 million and $24.8 million, respectively, in recorded investment in consumer mortgage loans collateralized by residential real estate property in the process of foreclosure.

Receivable_from_FDIC_for_Loss_1

Receivable from FDIC for Loss Share Agreements (Tables)	3 Months Ended
	Mar. 31, 2015
Receivable From FDIC For Loss Share Agreements [Abstract]
Changes in Receivable From FDIC	The following table provides changes in the receivable from the FDIC for the three-month periods ended March 31, 2015 and March 31, 2014.
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Beginning balance	$	28,701		$	93,397
	Amortization	(5,031		)	(17,744		)
	Cash payments to FDIC	5,762			3,490
	Post-acquisition adjustments	(8,092		)	(4,359		)
	Ending balance	$	21,340		$	74,784

Estimated_Fair_Values_Tables

Estimated Fair Values (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
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, 2015 and December 31, 2014. 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.
	(Dollars in thousands)	March 31, 2015				December 31, 2014
		Carrying value		Fair value		Carrying value		Fair value
	Cash and due from banks	$	495,901	$	495,901	$	604,182	$	604,182
	Overnight investments	2,458,923		2,458,923		1,724,919		1,724,919
	Investment securities available for sale	7,045,109		7,045,109		7,171,917		7,171,917
	Investment securities held to maturity	441		459		518		544
	Loans held for sale	66,508		66,508		63,696		63,696
	Net loans and leases	18,886,204		18,359,306		18,564,999		18,046,497
	Receivable from the FDIC for loss share agreements (1)	21,340		14,407		28,701		18,218
	Income earned not collected	63,165		63,165		57,254		57,254
	Federal Home Loan Bank stock	30,291		30,291		39,113		39,113
	Preferred stock and other acquired financial assets	13,689		14,688		13,689		14,708
	Mortgage servicing rights	16,436		16,719		16,688		16,736
	Deposits	26,300,830		25,718,225		25,678,577		25,164,683
	Short-term borrowings	941,850		941,850		987,184		987,184
	Long-term obligations	468,180		486,960		351,320		367,732
	Payable to the FDIC for loss share agreements	118,645		126,113		116,535		122,168
	Accrued interest payable	8,370		8,370		8,194		8,194
	Interest rate swap	3,761		3,761		4,337		4,337
	(1) The fair value of the FDIC receivable excludes receivable related to accretable yield to be amortized in prospective periods.
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, 2015 and December 31, 2014.
		March 31, 2015
				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	$	2,246,966	$	—	$	2,246,966	$	—
	Government agency	990,894		—		990,894		—
	Mortgage-backed securities	3,807,249		—		3,807,249		—
	Total investment securities available for sale	7,045,109		—		7,045,109		—
	Loans held for sale	66,508		—		66,508		—
	Liabilities measured at fair value
	Interest rate swaps accounted for as cash flow hedges	$	3,761	$	—	$	3,761	$	—
		December 31, 2014
				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	$	2,629,670	$	—	$	2,629,670	$	—
	Government agency	908,817		—		908,817		—
	Mortgage-backed securities	3,633,304		—		3,633,304		—
	Municipal securities	126		—		126		—
	Total investment securities available for sale	7,171,917		—		7,171,917		—
	Loans held for sale	63,696		—		63,696		—
	Liabilities measured at fair value
	Interest rate swaps accounted for as cash flow hedges	$	4,337	$	—	$	4,337	$	—
Fair Value Option	The following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for residential real estate loans held for sale measured at fair value as of March 31, 2015 and December 31, 2014.
		March 31, 2015
	(Dollars in thousands)	Fair Value		Aggregate Unpaid Principal Balance		Difference
	Loans held for sale	$	66,508	$	65,378	$	1,130
		December 31, 2014
		Fair Value		Aggregate Unpaid Principal Balance		Difference
	Loans held for sale	$	63,696	$	62,996	$	700
	No loans held for sale were 90 or more days past due or on nonaccrual status as of March 31, 2015 or December 31, 2014.
	The changes in fair value for residential real estate loans held for sale for which we elected the fair value option are included in the table below for the three months ended March 31, 2015.
		Three months ended March 31, 2015
	(Dollars in thousands)	Gains(Losses) From Fair Value Changes
	Loans held for sale	$	430
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, 2015 and December 31, 2014.
		March 31, 2015
				Fair value measurements using:
	(Dollars in thousands)	Fair value		Level 1 inputs		Level 2 inputs		Level 3 inputs
	Impaired loans	$	69,749	$	—	$	—	$	69,749
	Other real estate not covered under loss share agreements remeasured during current year	17,034		—		—		17,034
	Other real estate covered under loss share agreements remeasured during current year	3,714		—		—		3,714
	Mortgage servicing rights	14,225		—		—		14,225
		December 31, 2014
				Fair value measurements using:
		Fair value		Level 1 inputs		Level 2 inputs		Level 3 inputs
	Impaired loans	$	73,170	$	—	$	—	$	73,170
	Other real estate not covered under loss share agreements remeasured during current year	40,714		—		—		40,714
	Other real estate covered under loss share agreements remeasured during current year	17,664		—		—		17,664
	Mortgage servicing rights	13,562		—		—		13,562

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2015
BancShares Plan
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Benefit Costs	BancShares Plan
	For the three months ended March 31, 2015 and 2014, the components of net periodic benefit cost are as follows:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Service cost	$	3,600		$	3,381
	Interest cost	6,748			6,556
	Expected return on assets	(8,295		)	(7,812		)
	Amortization of prior service cost	53			53
	Amortization of net actuarial loss	2,833			1,546
	Net periodic benefit cost	$	4,939		$	3,724
Bancorporation Plan
Defined Benefit Plan Disclosure [Line Items]
Schedule of Net Benefit Costs	Bancorporation Plan
	For the three months ended March 31, 2015, the components of net periodic benefit cost are as follows:
		Three months ended March 31
	(Dollars in thousands)	2015
	Service cost	$	933
	Interest cost	1,628
	Expected return on assets	(2,869		)
	Amortization of prior service cost	—
	Amortization of net actuarial loss	—
	Net periodic benefit cost	$	(308	)

Derivatives_Tables

Derivatives (Tables) (Interest Rate Swap)	3 Months Ended
	Mar. 31, 2015
Interest Rate Swap
Derivative [Line Items]
Schedule Of Interest Rate Swaps
		March 31, 2015				December 31, 2014
	(Dollars in thousands)	Notional  amount		Estimated fair value of liability		Notional  amount		Estimated fair value of liability
	2011 interest rate swap hedging variable rate exposure on trust preferred securities 2011-2016	$	93,500	$	3,761	$	93,500	$	4,337

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule Of Accumulated Other Comprehensive Income (Loss)	Accumulated other comprehensive income (loss) included the following as of March 31, 2015 and December 31, 2014:
		March 31, 2015										December 31, 2014
	(Dollars in thousands)	Accumulated				Deferred			Accumulated			Accumulated			Deferred			Accumulated
		other				tax expense			other			other			tax expense			other
		comprehensive				(benefit)			comprehensive			comprehensive			(benefit)			comprehensive
		income (loss)							income (loss),			gain (loss)						gain (loss),
									net of tax									net of tax
	Unrealized gains on investment securities available for sale, net	$	33,632			$	13,081		$	20,551		$	8,343		$	3,245		$	5,098
	Unrealized loss on cash flow hedge	(3,761		)		(1,451		)	(2,310		)	(4,337		)	(1,673		)	(2,664		)
	Funded status of defined benefit plan	(87,810		)		(34,158		)	(53,652		)	(90,696		)	(35,281		)	(55,415		)
	Total	$	(57,939	)		$	(22,528	)	$	(35,411	)	$	(86,690	)	$	(33,709	)	$	(52,981	)
	The following table highlights changes in accumulated other comprehensive income (loss) by component for the three months ended March 31, 2015 and March 31, 2014:
		Three months ended March 31, 2015
	(Dollars in thousands)	Unrealized gains on available for sale securities1				Gains (losses) on cash flow hedges1			Defined benefit pension items1			Total
	Beginning balance	$	5,098			$	(2,664	)	$	(55,415	)	$	(52,981	)
	Other comprehensive income before reclassifications	18,602				354			—			18,956
	Amounts reclassified from accumulated other comprehensive (loss) income	(3,149		)		—			1,763			(1,386		)
	Net current period other comprehensive income	15,453				354			1,763			17,570
	Ending balance	$	20,551			$	(2,310	)	$	(53,652	)	$	(35,411	)
		Three months ended March 31, 2014
		Unrealized gains (losses) on available for sale securities1				Gains (losses) on cash flow hedges1			Defined benefit pension items1			Total
	Beginning balance	$	(10,091	)		$	(4,434	)	$	(10,743	)	$	(25,268	)
	Other comprehensive income before reclassifications	7,256				441			—			7,697
	Amounts reclassified from accumulated other comprehensive (loss) income	—				—			977			977
	Net current period other comprehensive income	7,256				441			977			8,674
	Ending balance	$	(2,835	)		$	(3,993	)	$	(9,766	)	$	(16,594	)
	1 All amounts are net of tax.
Reclassification out of Accumulated Other Comprehensive Income
	(Dollars in thousands)		Three months ended March 31, 2015
	Details about accumulated other comprehensive loss		Amount reclassified from accumulated other comprehensive (loss) income1				Affected line item in the statement where net income is presented
	Unrealized gains and losses on available for sale securities
			$	5,126			Securities gains
			(1,977		)		Income taxes
			$	3,149			Net income
	Amortization of defined benefit pension items
	Prior service costs		$	(53	)		Employee benefits
	Actuarial losses		(2,833		)		Employee benefits
			(2,886		)		Income before income taxes
			1,123				Provision for income taxes
			$	(1,763	)		Net income
	Total reclassifications for the period		$	1,386
			Three months ended March 31, 2014
	Details about accumulated other comprehensive loss		Amount reclassified from accumulated other comprehensive (loss) income1				Affected line item in the statement where net income is presented
	Amortization of defined benefit pension items
	Prior service costs		$	(53	)		Employee benefits
	Actuarial losses		(1,546		)		Employee benefits
			(1,599		)		Income before income taxes
			622				Provision for income taxes
			$	(977	)		Net income
	Total reclassifications for the period		$	(977	)
	1 Amounts in parentheses indicate debits to profit/loss.

Repurchase_Agreements_Repurcha1

Repurchase Agreements Repurchase Agreements (Tables)	3 Months Ended
	Mar. 31, 2015
Repurchase Agreements [Abstract]
Schedule of Repurchase Agreements [Table Text Block]	The remaining contractual maturity of the securities sold under agreements to repurchase by class of collateral pledged included in short-term borrowings in the Consolidated Balance Sheets as of March 31, 2015 and December 31, 2014 is presented in the following tables.
		March 31, 2015
		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	$	335,283	$	—	$	—	$	23,091	$	358,374
	Government agency	—		—		—		6,909		6,909
	Total borrowings	$	335,283	$	—	$	—	$	30,000	$	365,283
	Gross amount of recognized liabilities for repurchase agreements									$	365,283
		December 31, 2014
		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	$	162,924	$	—	$	—	$	23,086	$	186,010
	Government agency	—		—		—		6,914		6,914
	Mortgage-backed securities	131,501		—		—		—		131,501
	Total borrowings	$	294,425	$	—	$	—	$	30,000	$	324,425
	Gross amount of recognized liabilities for repurchase agreements									$	324,425

Mortgage_Servicing_Rights_Mort1

Mortgage Servicing Rights Mortgage Servicing Rights (Tables)	3 Months Ended
	Mar. 31, 2015
Mortgage Servicing Rights [Abstract]
Mortgage servicing rights	The activity of the servicing asset for first quarter 2015 and 2014 is presented in the following table:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Balance at January 1	$	16,688		$	16
	Servicing rights originated	662			—
	Amortization	(852		)	(164		)
	Servicing rights acquired in the 1st Financial merger	—			148
	Valuation allowance provision	$	(62	)	$	—
	Balance at March 31	$	16,436		$	—
Mortgage servicing rights valuation allowance	The following table presents the activity in the servicing asset valuation allowance for first quarter 2015 and 2014:
		Three months ended March 31
	(Dollars in thousands)	2015			2014
	Balance at January 1	$	850		$	—
	Valuation allowance provision	62			—
	Balance at March 31	$	912		$	—
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, 2015 and December 31, 2014 were as follows:
		March 31, 2015			December 31, 2014
	Discount rate - conventional fixed loans	6.95		%	7.2		%
	Discount rate - all loans excluding conventional fixed loans	8.95		%	9.2		%
	Weighted average constant prepayment rate	16.07		%	14.25		%
	Weighted average cost to service loans	$	56.02		$	56.02

Accounting_Policies_and_Basis_2

Accounting Policies and Basis of Presentation Accounting Policies and Basis of Presentation (Recently Adopted Accounting Standards) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Mar. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Qualified Affordable Housing Projects Investments		$65,300,000	$57,100,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$2,400,000

Business_Combinations_Details

Business Combinations (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Oct. 02, 2014	Feb. 14, 2015	Feb. 13, 2015	Jan. 01, 2014	Oct. 01, 2014
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value					$149,294,000	$316,327,000
Gain on acquisition	37,555,000	0
Merger-related expenses	2,997,000	2,453,000
Bancorporation
Business Acquisition [Line Items]
BancShares number of shares owned in Bancorporation			32,042
Fair value of Bancorporation shares owned by BancShares							29,551,000
Investment securities available for sale							2,011,263,000
Loans							4,491,067,000
Intangible asset							109,416,000
Total assets acquired							8,275,367,000
Deposits							7,174,817,000
Total liabilities assumed							7,655,408,000
Cash paid to shareholders			-30,394,000
Cash and overnight investments							1,280,000,000
Goodwill acquired			4,233,000
Pro forma revenue	323,524,000
Pro forma net income	37,230,000
Capitol City Bank and Trust
Business Acquisition [Line Items]
Cash and cash equivalents					19,622,000
Investment securities available for sale					35,413,000
Intangible asset					500,000
Other assets					1,731,000
Total assets acquired					206,560,000
Deposits					266,352,000
Short-term borrowings					5,501,000
Other liabilities					667,000
Total liabilities assumed					272,520,000
Fair value of net assets (liabilities) assumed					-65,960,000
Cash received from FDIC					103,515,000
Gain on acquisition				37,555,000
Merger-related expenses	200,000
Revenue generated	1,300,000
Class A Common Stock | Bancorporation
Business Acquisition [Line Items]
Right to receive number of shares conversion			2,586,762
Value of shares of BancShares common stock issued to Bancorporation							560,370,000
Class B Common Stock | Bancorporation
Business Acquisition [Line Items]
Right to receive number of shares conversion			18,202
Value of shares of BancShares common stock issued to Bancorporation							3,877,000
Shares and Cash | Bancorporation
Business Acquisition [Line Items]
Right to receive cash per share			$50
Shares and Cash | Class A Common Stock | Bancorporation
Business Acquisition [Line Items]
Right to receive number of shares conversion			4
Shares Only | Class A Common Stock | Bancorporation
Business Acquisition [Line Items]
Right to receive number of shares conversion			3.58
Shares Only | Class B Common Stock | Bancorporation
Business Acquisition [Line Items]
Right to receive number of shares conversion			0.42

Business_Combinations_Loans_Ac

Business Combinations (Loans Acquired) (Details) (USD $)	Feb. 13, 2015	Jan. 01, 2014
In Thousands, unless otherwise specified
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	$149,294	$316,327
Commercial
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	135,604
Commercial | Construction and land development
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	4,221
Commercial | Mortgage
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	125,202
Commercial | Other commercial real estate
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	3,132
Commercial | Commercial and industrial
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	3,049
Noncommerical
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	13,690
Noncommerical | Mortgage
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	12,050
Noncommerical | Consumer
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	$1,640

Investments_Aggregate_Values_a

Investments (Aggregate Values and Unrealized Gains and Losses) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investment securities available for sale
Cost	$7,011,477	$7,163,574
Gross Unrealized Gains	39,354	20,589
Gross Unrealized Losses	5,722	12,246
Fair Value	7,045,109	7,171,917
Investment securities held to maturity
Cost	441	518
U. S. Treasury
Investment securities available for sale
Cost	2,237,002	2,626,900
Gross Unrealized Gains	9,966	2,922
Gross Unrealized Losses	2	152
Fair Value	2,246,966	2,629,670
Government Agency
Investment securities available for sale
Cost	988,563	908,362
Gross Unrealized Gains	2,382	702
Gross Unrealized Losses	51	247
Fair Value	990,894	908,817
Mortgage Backed Securities, Other [Member]
Investment securities available for sale
Cost	3,785,912	3,628,187
Gross Unrealized Gains	27,006	16,964
Gross Unrealized Losses	5,669	11,847
Fair Value	3,807,249	3,633,304
Investment securities held to maturity
Cost	441	518
Held To Maturity Securities Accumulated Unrecognized Holding Gain	18	26
Held To Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Fair Value	459	544
State, County and Municipal
Investment securities available for sale
Cost		125
Gross Unrealized Gains		1
Gross Unrealized Losses		0
Fair Value		$126

Investments_Maturity_Informati

Investments (Maturity Information) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investment securities available for sale
Total investment securities available for sale, cost	$7,011,477	$7,163,574
Total investment securities available for sale, fair value	7,045,109	7,171,917
Investment securities held to maturity
Investment securities held to maturity	441	518
Debt Securities
Investment securities available for sale
Maturing in one year or less, cost	504,826	447,866
Maturing in one through five years, cost	2,720,739	3,087,521
Maturing in one year or less, fair value	505,182	447,992
Maturing in one through five years, fair value	2,732,678	3,090,621
Mortgage Backed Securities, Other [Member]
Investment securities available for sale
Total investment securities available for sale, cost	3,785,912	3,628,187
Total investment securities available for sale, fair value	3,807,249	3,633,304
Investment securities held to maturity
Investment securities held to maturity	441	518
Fair Value	$459	$544

Investments_Unrealized_Losses_

Investments (Unrealized Losses) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investment securities available for sale:
Fair Value, Less than 12 months	$645,300	$1,173,274
Unrealized Losses, Less than 12 months	1,698	2,203
Fair Value, 12 months or more	317,685	832,420
Unrealized Losses, Greater than 12 months	4,024	10,043
Fair Value, Total	962,985	2,005,694
Unrealized Losses, Total	5,722	12,246
U. S. Treasury
Investment securities available for sale:
Fair Value, Less than 12 months	13,024	338,612
Unrealized Losses, Less than 12 months	2	151
Fair Value, 12 months or more	0	1,015
Unrealized Losses, Greater than 12 months	0	1
Fair Value, Total	13,024	339,627
Unrealized Losses, Total	2	152
Government Agency
Investment securities available for sale:
Fair Value, Less than 12 months	69,660	261,288
Unrealized Losses, Less than 12 months	51	247
Fair Value, 12 months or more	0	0
Unrealized Losses, Greater than 12 months	0	0
Fair Value, Total	69,660	261,288
Unrealized Losses, Total	51	247
Mortgage Backed Securities, Other [Member]
Investment securities available for sale:
Fair Value, Less than 12 months	562,616	573,374
Unrealized Losses, Less than 12 months	1,645	1,805
Fair Value, 12 months or more	317,685	831,405
Unrealized Losses, Greater than 12 months	4,024	10,042
Fair Value, Total	880,301	1,404,779
Unrealized Losses, Total	5,669	11,847
State, County and Municipal
Investment securities available for sale:
Unrealized Losses, Total		$0

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	investments
Investments [Abstract]
Securities gains (losses)	$5,126,000	$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	317,685,000		832,420,000
Unrealized Losses, Greater than 12 months	4,024,000		10,043,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	38
Investment value deemed to be OTTI	0
Investment securities, aggregate carrying value, pledged as collateral	$4,450,000,000		$4,370,000,000

Investments_Securities_Gains_L

Investments (Securities Gains (Losses)) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments [Abstract]
Gross gains on sales of investment securities available for sale	$5,135	$0
Gross losses on sales of investment securities available for sale	9	0
Total securities gains (losses)	$5,126	$0

Loans_and_Leases_Narrative_Det

Loans and Leases (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
PCI loans	$1,247,343,000	$1,186,498,000	$1,270,818,000	$1,029,426,000
Noncovered loans pledged to secure debt obligations	3,250,000,000	3,160,000,000
Charge off of past due business credit card loans (days)	120 days
Loans and Leases Receivable, Collateral for Secured Borrowings	2,300,000,000	2,200,000,000
Advances from Federal Home Loan Banks	290,300,000	240,300,000
Federal Home Loan Bank Advances, Current Borrowing Capacity	2,010,000,000	1,960,000,000
Loans and Leases Receivable, Gross, Carrying Amount, Covered	443,100,000	485,300,000
Bancorporation
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	55,700,000	61,200,000
Sun American Bank
Financing Receivable, Recorded Investment [Line Items]
PCI loans	43,200,000
First Regional Bank
Financing Receivable, Recorded Investment [Line Items]
PCI loans	53,900,000
Williamsburg First National Bank
Financing Receivable, Recorded Investment [Line Items]
PCI loans	$8,400,000

Loans_and_Leases_Loans_and_Lea

Loans and Leases (Loans and Leases Outstanding) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Originated	$17,844,414	$17,582,967
PCI loans	1,247,343	1,186,498	1,270,818	1,029,426
Total loans and leases	19,091,757	18,769,465
Commercial
Originated	11,493,458	11,263,074
PCI loans	791,756	726,123
Commercial | Construction and land development
Originated	608,556	550,568
PCI loans	70,049	78,079
Commercial | Mortgage
Originated	7,591,745	7,552,948
PCI loans	653,846	577,518
Commercial | Commercial and industrial
Originated	2,072,414	1,988,934
PCI loans	24,134	27,254
Commercial | Lease financing
Originated	603,737	571,916
Commercial | Other commercial real estate
Originated	262,293	244,875
PCI loans	40,841	40,193
Commercial | Other
Originated	354,713	353,833
PCI loans	2,886	3,079
Noncommerical
Originated	6,350,956	6,319,893
PCI loans	455,587	460,375
Noncommerical | Mortgage
Originated	2,524,549	2,520,542
PCI loans	380,490	382,340
Noncommerical | Construction and land development
Originated	170,208	120,097
PCI loans	874	912
Noncommerical | Revolving mortgage
Originated	2,528,257	2,561,800
PCI loans	70,363	74,109
Noncommerical | Consumer
Originated	1,127,942	1,117,454
PCI loans	$3,860	$3,014

Loans_and_Leases_Composition_o

Loans and Leases (Composition of the Loans and Leases Outstanding By Credit Quality Indicator) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	$1,247,343	$1,186,498	$1,270,818	$1,029,426
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	11,493,458	11,263,074
PCI loans	791,756	726,123
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	608,556	550,568
PCI loans	70,049	78,079
Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	7,591,745	7,552,948
PCI loans	653,846	577,518
Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	262,293	244,875
PCI loans	40,841	40,193
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,072,414	1,988,934
PCI loans	24,134	27,254
Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	603,737	571,916
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	354,713	353,833
PCI loans	2,886	3,079
Commercial | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	11,070,735	10,825,323
PCI loans	371,135	342,172
Commercial | Pass | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	590,298	525,711
PCI loans	13,832	13,514
Commercial | Pass | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	7,341,243	7,284,714
PCI loans	333,368	300,187
Commercial | Pass | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	260,592	242,053
PCI loans	9,727	11,033
Commercial | Pass | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,931,078	1,859,415
PCI loans	13,525	16,637
Commercial | Pass | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	597,464	564,319
Commercial | Pass | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	350,060	349,111
PCI loans	683	801
Commercial | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	157,884	182,453
PCI loans	141,884	125,195
Commercial | Special Mention | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	15,679	20,025
PCI loans	4,287	6,063
Commercial | Special Mention | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	115,411	129,247
PCI loans	118,209	98,724
Commercial | Special Mention | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	501	909
PCI loans	16,425	16,271
Commercial | Special Mention | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	21,771	27,683
PCI loans	2,963	4,137
Commercial | Special Mention | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,609	3,205
Commercial | Special Mention | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,913	1,384
PCI loans	0	0
Commercial | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	149,792	157,333
PCI loans	259,917	247,138
Commercial | Substandard | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,291	4,720
PCI loans	44,663	53,739
Commercial | Substandard | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	131,672	134,677
PCI loans	193,435	171,920
Commercial | Substandard | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,049	1,765
PCI loans	12,948	12,889
Commercial | Substandard | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	8,806	8,878
PCI loans	6,739	6,312
Commercial | Substandard | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	3,284	3,955
Commercial | Substandard | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,690	3,338
PCI loans	2,132	2,278
Commercial | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	6,770	2,895
PCI loans	15,437	9,241
Commercial | Doubtful | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	0	0
PCI loans	4,656	2,809
Commercial | Doubtful | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,039	2,366
PCI loans	8,456	6,302
Commercial | Doubtful | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	0	0
PCI loans	1,741	0
Commercial | Doubtful | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	4,402	164
PCI loans	513	130
Commercial | Doubtful | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	329	365
Commercial | Doubtful | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	0	0
PCI loans	71	0
Commercial | Ungraded
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	108,277	95,070
PCI loans	3,383	2,377
Commercial | Ungraded | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	288	112
PCI loans	2,611	1,954
Commercial | Ungraded | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,380	1,944
PCI loans	378	385
Commercial | Ungraded | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	151	148
PCI loans	0	0
Commercial | Ungraded | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	106,357	92,794
PCI loans	394	38
Commercial | Ungraded | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	51	72
Commercial | Ungraded | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	50	0
PCI loans	0	0
Noncommerical
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	455,587	460,375
Noncommerical | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	380,490	382,340
Noncommerical | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	70,363	74,109
Noncommerical | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	874	912
Noncommerical | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	3,860	3,014
Purchased credit-impaired | Noncommerical
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	388,349	398,225
PCI loans	455,587	460,375
30-59 Days Past Due	21,672	12,984
60-89 Days Past Due	7,836	10,443
90 Days or Greater	37,730	38,723
Purchased credit-impaired | Noncommerical | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	320,607	326,589
PCI loans	380,490	382,340
30-59 Days Past Due	18,742	11,432
60-89 Days Past Due	6,804	10,073
90 Days or Greater	34,337	34,246
Purchased credit-impaired | Noncommerical | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	63,579	68,548
PCI loans	70,363	74,109
30-59 Days Past Due	2,800	1,405
60-89 Days Past Due	1,019	345
90 Days or Greater	2,965	3,811
Purchased credit-impaired | Noncommerical | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	592	506
PCI loans	874	912
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or Greater	282	406
Purchased credit-impaired | Noncommerical | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,571	2,582
PCI loans	3,860	3,014
30-59 Days Past Due	130	147
60-89 Days Past Due	13	25
90 Days or Greater	146	260
Non-PCI Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	17,844,414	17,582,967
Current	17,732,161	17,481,500
30-59 Days Past Due	71,450	57,321
60-89 Days Past Due	15,735	19,548
90 Days or Greater	25,068	24,598
Non-PCI Loans | Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	608,556	550,568
Current	604,091	547,766
30-59 Days Past Due	2,709	1,796
60-89 Days Past Due	712	621
90 Days or Greater	1,044	385
Non-PCI Loans | Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	7,591,745	7,552,948
Current	7,554,745	7,528,738
30-59 Days Past Due	22,635	11,367
60-89 Days Past Due	5,920	4,782
90 Days or Greater	8,445	8,061
Non-PCI Loans | Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	262,293	244,875
Current	261,456	244,497
30-59 Days Past Due	583	206
60-89 Days Past Due	58	70
90 Days or Greater	196	102
Non-PCI Loans | Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,072,414	1,988,934
Current	2,063,830	1,984,168
30-59 Days Past Due	6,290	2,843
60-89 Days Past Due	1,724	1,545
90 Days or Greater	570	378
Non-PCI Loans | Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	603,737	571,916
Current	603,250	570,275
30-59 Days Past Due	476	1,631
60-89 Days Past Due	11	8
90 Days or Greater	0	2
Non-PCI Loans | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	354,713	353,833
Current	354,135	351,721
30-59 Days Past Due	380	146
60-89 Days Past Due	65	1,966
90 Days or Greater	133	0
Non-PCI Loans | Noncommerical
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	6,350,956	6,319,893
Current	6,290,654	6,254,335
30-59 Days Past Due	38,377	39,332
60-89 Days Past Due	7,245	10,556
90 Days or Greater	14,680	15,670
Non-PCI Loans | Noncommerical | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,524,549	2,520,542
Current	2,490,453	2,482,281
30-59 Days Past Due	21,844	23,288
60-89 Days Past Due	2,896	6,018
90 Days or Greater	9,356	8,955
Non-PCI Loans | Noncommerical | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,528,257	2,561,800
Current	2,510,879	2,542,807
30-59 Days Past Due	10,288	11,097
60-89 Days Past Due	2,794	2,433
90 Days or Greater	4,296	5,463
Non-PCI Loans | Noncommerical | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	170,208	120,097
Current	168,199	119,094
30-59 Days Past Due	2,009	370
60-89 Days Past Due	0	486
90 Days or Greater	0	147
Non-PCI Loans | Noncommerical | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,127,942	1,117,454
Current	1,121,123	1,110,153
30-59 Days Past Due	4,236	4,577
60-89 Days Past Due	1,555	1,619
90 Days or Greater	$1,028	$1,105

Loans_and_Leases_Aging_Of_The_

Loans and Leases (Aging Of The Outstanding Loans and Leases By Class Excluding Loans Impaired At Acquisition Date) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	$11,493,458	$11,263,074
Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	608,556	550,568
Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	7,591,745	7,552,948
Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	262,293	244,875
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,072,414	1,988,934
Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	603,737	571,916
Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, not acquired in a transfer accounted for as debt securities	354,713	353,833
Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	71,450	57,321
60-89 Days Past Due	15,735	19,548
90 Days or Greater	25,068	24,598
Total	112,253	101,467
Current	17,732,161	17,481,500
Loans and leases, not acquired in a transfer accounted for as debt securities	17,844,414	17,582,967
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2,709	1,796
60-89 Days Past Due	712	621
90 Days or Greater	1,044	385
Total	4,465	2,802
Current	604,091	547,766
Loans and leases, not acquired in a transfer accounted for as debt securities	608,556	550,568
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	22,635	11,367
60-89 Days Past Due	5,920	4,782
90 Days or Greater	8,445	8,061
Total	37,000	24,210
Current	7,554,745	7,528,738
Loans and leases, not acquired in a transfer accounted for as debt securities	7,591,745	7,552,948
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	583	206
60-89 Days Past Due	58	70
90 Days or Greater	196	102
Total	837	378
Current	261,456	244,497
Loans and leases, not acquired in a transfer accounted for as debt securities	262,293	244,875
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	6,290	2,843
60-89 Days Past Due	1,724	1,545
90 Days or Greater	570	378
Total	8,584	4,766
Current	2,063,830	1,984,168
Loans and leases, not acquired in a transfer accounted for as debt securities	2,072,414	1,988,934
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	476	1,631
60-89 Days Past Due	11	8
90 Days or Greater	0	2
Total	487	1,641
Current	603,250	570,275
Loans and leases, not acquired in a transfer accounted for as debt securities	603,737	571,916
Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	380	146
60-89 Days Past Due	65	1,966
90 Days or Greater	133	0
Total	578	2,112
Current	354,135	351,721
Loans and leases, not acquired in a transfer accounted for as debt securities	354,713	353,833
Non-PCI Loans | Noncommerical
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	38,377	39,332
60-89 Days Past Due	7,245	10,556
90 Days or Greater	14,680	15,670
Current	6,290,654	6,254,335
Loans and leases, not acquired in a transfer accounted for as debt securities	6,350,956	6,319,893
Non-PCI Loans | Noncommerical | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	21,844	23,288
60-89 Days Past Due	2,896	6,018
90 Days or Greater	9,356	8,955
Total	34,096	38,261
Current	2,490,453	2,482,281
Loans and leases, not acquired in a transfer accounted for as debt securities	2,524,549	2,520,542
Non-PCI Loans | Noncommerical | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	10,288	11,097
60-89 Days Past Due	2,794	2,433
90 Days or Greater	4,296	5,463
Total	17,378	18,993
Current	2,510,879	2,542,807
Loans and leases, not acquired in a transfer accounted for as debt securities	2,528,257	2,561,800
Non-PCI Loans | Noncommerical | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2,009	370
60-89 Days Past Due	0	486
90 Days or Greater	0	147
Total	2,009	1,003
Current	168,199	119,094
Loans and leases, not acquired in a transfer accounted for as debt securities	170,208	120,097
Non-PCI Loans | Noncommerical | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	4,236	4,577
60-89 Days Past Due	1,555	1,619
90 Days or Greater	1,028	1,105
Total	6,819	7,301
Current	1,121,123	1,110,153
Loans and leases, not acquired in a transfer accounted for as debt securities	$1,127,942	$1,117,454

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 $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	$66,046	$44,005
Loans and leases greater than 90 days and accruing	3,089	11,250
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	1,497	343
Loans and leases greater than 90 days and accruing	202	111
Commercial | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	26,058	24,720
Loans and leases greater than 90 days and accruing	764	1,003
Commercial | Other commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	650	619
Loans and leases greater than 90 days and accruing	0	35
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	5,691	1,741
Loans and leases greater than 90 days and accruing	294	239
Commercial | Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	346	374
Loans and leases greater than 90 days and accruing	0	2
Noncommerical | Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	19,238	14,242
Loans and leases greater than 90 days and accruing	1,153	3,191
Noncommerical | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	2,052	1,966
Loans and leases greater than 90 days and accruing	31	0
Noncommerical | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	0	0
Loans and leases greater than 90 days and accruing	0	147
Noncommerical | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	9,837	0
Loans and leases greater than 90 days and accruing	19	5,463
Noncommerical | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccruing	677	0
Loans and leases greater than 90 days and accruing	$626	$1,059

Loans_and_Leases_Changes_In_Ca

Loans and Leases (Changes In Carrying Value Of Acquired Impaired Loans) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 13, 2015	Dec. 31, 2014	Jan. 01, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	$1,247,343,000	$1,270,818,000		$1,186,498,000		$1,029,426,000
Impaired Financing Receivable, Unpaid Principal Balance	2,092,936,000	1,727,492,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			149,294,000		316,327,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Accretion	25,067,000	30,200,000
Carrying Value of Acquired Impaired Loans [Roll Forward]
Reductions for repayments, foreclosures and changes in carrying value, net of accretion	-113,516,000	-105,135,000
Loans on the Cost Recovery Method
Carrying Value of Acquired Impaired Loans [Roll Forward]
Ending balance	13,000,000			33,400,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	791,756,000			726,123,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			135,604,000
Noncommerical
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	455,587,000			460,375,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			13,690,000
Construction and land development | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	70,049,000			78,079,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			4,221,000
Mortgage | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	653,846,000			577,518,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			125,202,000
Mortgage | Noncommerical
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	380,490,000			382,340,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			12,050,000
Other commercial real estate | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	40,841,000			40,193,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			3,132,000
Commercial and industrial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	24,134,000			27,254,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			3,049,000
Consumer | Noncommerical
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans	3,860,000			3,014,000
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value			$1,640,000

Loans_and_Leases_Changes_In_Ca1

Loans and Leases (Changes In Carrying Amount Of Accretable Yield) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Loans and Leases Receivable Disclosure [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield	$422,286	$490,245	$418,160	$439,990
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Additions	55,186	84,295
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Accretion	25,067	30,200
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	1,294	6,048
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Changes in Expected Cash Flows Not Affecting Nonaccretable Difference	($27,287)	($9,888)

Loans_and_Leases_Loans_and_Lea1

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 $)	Feb. 13, 2015	Jan. 01, 2014
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	$251,800
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition	204,480
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	$149,294	$316,327

Allowance_for_Loan_and_Lease_L2

Allowance for Loan and Lease Losses (Summary of Activity In Allowance for Loan and Lease Losses) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Loans and Leases, Baseline for Meaurement			$500,000
Loans and Leases Evaluated for Impairment [Abstract]
Net loans and leases	18,886,204,000		18,564,999,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Allowance for loan and lease losses	205,553,000		204,466,000
PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	21,629,000	53,520,000
Provisions	-2,864,000	-2,273,000
Charge-offs	-1,146,000	-6,254,000
Recoveries	0	0
Ending balance	17,619,000	44,993,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	17,619,000	44,993,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	17,619,000		21,629,000
Loans and leases acquired with deteriorated credit quality	1,247,343,000		1,186,498,000
PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	150,000	1,320,000
Provisions	191,000	3,355,000
Charge-offs	0	-199,000
Recoveries	0	0
Ending balance	341,000	4,476,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	341,000	4,476,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	341,000		150,000
Loans and leases acquired with deteriorated credit quality	70,049,000		78,079,000
PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,135,000	29,906,000
Provisions	-925,000	-3,386,000
Charge-offs	-334,000	-3,517,000
Recoveries	0	0
Ending balance	8,876,000	23,003,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	8,876,000	23,003,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	8,876,000		10,135,000
Loans and leases acquired with deteriorated credit quality	653,846,000		577,518,000
PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	75,000	1,354,000
Provisions	119,000	-150,000
Charge-offs	0	0
Recoveries	0	0
Ending balance	194,000	1,204,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	194,000	1,204,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	194,000		75,000
Loans and leases acquired with deteriorated credit quality	40,841,000		40,193,000
PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,240,000	5,275,000
Provisions	-1,031,000	-336,000
Charge-offs	-198,000	-2,683,000
Recoveries	0	0
Ending balance	11,000	2,256,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	11,000	2,256,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	11,000		1,240,000
Loans and leases acquired with deteriorated credit quality	24,134,000		27,254,000
PCI Loans | Noncommerical | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,820,000	11,802,000
Provisions	-863,000	-2,300,000
Charge-offs	-85,000	262,000
Recoveries	0	0
Ending balance	4,872,000	9,764,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	4,872,000	9,764,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	4,872,000		5,820,000
Loans and leases acquired with deteriorated credit quality	380,490,000		382,339,000
PCI Loans | Noncommerical | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	183,000	682,000
Provisions	-152,000	-99,000
Charge-offs	0	0
Recoveries	0	0
Ending balance	31,000	583,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	31,000	583,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	31,000		183,000
Loans and leases acquired with deteriorated credit quality	874,000		912,000
PCI Loans | Noncommerical | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,999,000	2,959,000
Provisions	-655,000	634,000
Charge-offs	-73,000	-100,000
Recoveries	0	0
Ending balance	3,271,000	3,493,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	3,271,000	3,493,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	3,271,000		3,999,000
Loans and leases acquired with deteriorated credit quality	70,363,000		74,109,000
PCI Loans | Noncommerical | Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	27,000	222,000
Provisions	452,000	9,000
Charge-offs	-456,000	-17,000
Recoveries	0	0
Ending balance	23,000	214,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	23,000	214,000
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	23,000		27,000
Loans and leases acquired with deteriorated credit quality	6,746,000		6,094,000
Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	182,837,000	179,874,000
Provisions	8,656,000	370,000
Charge-offs	-6,030,000	-4,422,000
Recoveries	2,471,000	2,127,000
Ending balance	187,934,000	177,949,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	14,686,000		15,717,000
ALLL for loans and leases collectively evaluated for impairment	173,248,000		167,120,000
Total allowance for loan and lease losses	187,934,000	177,949,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	118,078,000		119,593,000
Loans and leases collectively evaluated for impairment	17,726,336,000		17,463,374,000
Net loans and leases	17,844,414,000		17,582,967,000
Non-PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,961,000	10,335,000
Provisions	1,103,000	1,885,000
Charge-offs	-18,000	0
Recoveries	62,000	26,000
Ending balance	13,108,000	12,246,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	182,000		92,000
ALLL for loans and leases collectively evaluated for impairment	12,926,000		11,869,000
Total allowance for loan and lease losses	13,108,000	12,246,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	2,972,000		1,620,000
Loans and leases collectively evaluated for impairment	605,584,000		548,948,000
Net loans and leases	608,556,000		550,568,000
Non-PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	85,189,000	100,257,000
Provisions	-3,679,000	-6,979,000
Charge-offs	-233,000	-168,000
Recoveries	761,000	1,107,000
Ending balance	82,038,000	94,217,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	7,494,000		8,610,000
ALLL for loans and leases collectively evaluated for impairment	74,544,000		76,579,000
Total allowance for loan and lease losses	82,038,000	94,217,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	77,291,000		82,803,000
Loans and leases collectively evaluated for impairment	7,514,454,000		7,470,145,000
Net loans and leases	7,591,745,000		7,552,948,000
Non-PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	732,000	1,009,000
Provisions	458,000	-74,000
Charge-offs	-169,000	0
Recoveries	10,000	10,000
Ending balance	1,031,000	945,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	104,000		112,000
ALLL for loans and leases collectively evaluated for impairment	927,000		620,000
Total allowance for loan and lease losses	1,031,000	945,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	543,000		584,000
Loans and leases collectively evaluated for impairment	261,750,000		244,291,000
Net loans and leases	262,293,000		244,875,000
Non-PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	30,727,000	22,362,000
Provisions	7,546,000	1,976,000
Charge-offs	-1,713,000	-496,000
Recoveries	394,000	179,000
Ending balance	36,954,000	24,021,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	2,809,000		1,743,000
ALLL for loans and leases collectively evaluated for impairment	34,145,000		28,984,000
Total allowance for loan and lease losses	36,954,000	24,021,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	13,969,000		11,040,000
Loans and leases collectively evaluated for impairment	2,058,445,000		1,977,894,000
Net loans and leases	2,072,414,000		1,988,934,000
Non-PCI Loans | Commercial | Lease financing
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,286,000	4,749,000
Provisions	11,000	-524,000
Charge-offs	-15,000	-58,000
Recoveries	11,000	16,000
Ending balance	4,293,000	4,183,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	236,000		150,000
ALLL for loans and leases collectively evaluated for impairment	4,057,000		4,136,000
Total allowance for loan and lease losses	4,293,000	4,183,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	1,492,000		623,000
Loans and leases collectively evaluated for impairment	602,245,000		571,293,000
Net loans and leases	603,737,000		571,916,000
Non-PCI Loans | Commercial | Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,184,000	190,000
Provisions	-218,000	272,000
Charge-offs	0	-8,000
Recoveries	15,000	0
Ending balance	2,981,000	454,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,955,000		1,972,000
ALLL for loans and leases collectively evaluated for impairment	1,026,000		1,212,000
Total allowance for loan and lease losses	2,981,000	454,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	1,977,000		2,000,000
Loans and leases collectively evaluated for impairment	352,736,000		351,833,000
Net loans and leases	354,713,000		353,833,000
Non-PCI Loans | Noncommerical | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,661,000	10,511,000
Provisions	813,000	609,000
Charge-offs	-284,000	-184,000
Recoveries	138,000	8,000
Ending balance	11,328,000	10,944,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,177,000		1,360,000
ALLL for loans and leases collectively evaluated for impairment	10,151,000		9,301,000
Total allowance for loan and lease losses	11,328,000	10,944,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	15,195,000		14,913,000
Loans and leases collectively evaluated for impairment	2,509,354,000		2,505,629,000
Net loans and leases	2,524,549,000		2,520,542,000
Non-PCI Loans | Noncommerical | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	892,000	681,000
Provisions	118,000	577,000
Charge-offs	-22,000	-71,000
Recoveries	68,000	62,000
Ending balance	1,056,000	1,249,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	90,000		71,000
ALLL for loans and leases collectively evaluated for impairment	966,000		821,000
Total allowance for loan and lease losses	1,056,000	1,249,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	733,000		1,340,000
Loans and leases collectively evaluated for impairment	169,475,000		118,757,000
Net loans and leases	170,208,000		120,097,000
Non-PCI Loans | Noncommerical | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	18,650,000	16,239,000
Provisions	-462,000	1,353,000
Charge-offs	-793,000	-1,260,000
Recoveries	134,000	76,000
Ending balance	17,529,000	16,408,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	108,000		1,052,000
ALLL for loans and leases collectively evaluated for impairment	17,421,000		17,598,000
Total allowance for loan and lease losses	17,529,000	16,408,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	2,922,000		3,675,000
Loans and leases collectively evaluated for impairment	2,525,335,000		2,558,125,000
Net loans and leases	2,528,257,000		2,561,800,000
Non-PCI Loans | Noncommerical | Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	16,555,000	13,541,000
Provisions	2,966,000	1,275,000
Charge-offs	-2,783,000	-2,177,000
Recoveries	878,000	643,000
Ending balance	17,616,000	13,282,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	531,000		555,000
ALLL for loans and leases collectively evaluated for impairment	17,085,000		16,000,000
Total allowance for loan and lease losses	17,616,000	13,282,000
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	984,000		995,000
Loans and leases collectively evaluated for impairment	1,126,958,000		1,116,459,000
Net loans and leases	$1,127,942,000		$1,117,454,000

Allowance_for_Loan_and_Lease_L3

Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	$2,092,936,000	$1,727,492,000
Allowance for loan and lease losses	205,553,000		204,466,000
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	126,823,000		133,466,000
ALLL for loans and leases individually evaluated for impairment	14,686,000		15,717,000
Financing Receivable, Individually Evaluated for Impairment	118,078,000		119,593,000
Average balance	121,995,000	131,647,000
Interest income recognized	1,093,000	1,513,000
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	4,228,000		6,945,000
ALLL for loans and leases individually evaluated for impairment	182,000		92,000
Financing Receivable, Individually Evaluated for Impairment	2,972,000		1,620,000
Average balance	3,052,000	1,031,000
Interest income recognized	35,000	15,000
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	81,826,000		87,702,000
ALLL for loans and leases individually evaluated for impairment	7,494,000		8,610,000
Financing Receivable, Individually Evaluated for Impairment	77,291,000		82,803,000
Average balance	80,553,000	94,547,000
Interest income recognized	769,000	1,120,000
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	847,000		913,000
ALLL for loans and leases individually evaluated for impairment	104,000		112,000
Financing Receivable, Individually Evaluated for Impairment	543,000		584,000
Average balance	551,000	1,796,000
Interest income recognized	1,000	21,000
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	14,939,000		12,197,000
ALLL for loans and leases individually evaluated for impairment	2,809,000		1,743,000
Financing Receivable, Individually Evaluated for Impairment	13,969,000		11,040,000
Average balance	14,229,000	10,234,000
Interest income recognized	103,000	118,000
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,492,000		623,000
ALLL for loans and leases individually evaluated for impairment	236,000		150,000
Financing Receivable, Individually Evaluated for Impairment	1,492,000		623,000
Average balance	1,590,000	284,000
Interest income recognized	18,000	4,000
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,977,000		2,000,000
ALLL for loans and leases individually evaluated for impairment	1,955,000		1,972,000
Financing Receivable, Individually Evaluated for Impairment	1,977,000		2,000,000
Average balance	1,990,000	0
Interest income recognized	0	0
Non-PCI Loans | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	15,852,000		15,746,000
ALLL for loans and leases individually evaluated for impairment	1,177,000		1,360,000
Financing Receivable, Individually Evaluated for Impairment	15,195,000		14,913,000
Average balance	15,364,000	16,482,000
Interest income recognized	125,000	174,000
Non-PCI Loans | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	733,000		1,340,000
ALLL for loans and leases individually evaluated for impairment	90,000		71,000
Financing Receivable, Individually Evaluated for Impairment	733,000		1,340,000
Average balance	658,000	2,322,000
Interest income recognized	7,000	29,000
Non-PCI Loans | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3,925,000		4,933,000
ALLL for loans and leases individually evaluated for impairment	108,000		1,052,000
Financing Receivable, Individually Evaluated for Impairment	2,922,000		3,675,000
Average balance	2,986,000	3,892,000
Interest income recognized	16,000	27,000
Non-PCI Loans | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,004,000		1,067,000
ALLL for loans and leases individually evaluated for impairment	531,000		555,000
Financing Receivable, Individually Evaluated for Impairment	984,000		995,000
Average balance	1,022,000	1,059,000
Interest income recognized	19,000	5,000
Non-PCI Loans | With A Recorded Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	83,497,000		87,007,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	2,114,000		996,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	53,220,000		57,324,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	104,000		112,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	13,123,000		10,319,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,221,000		319,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,977,000		2,000,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	8,662,000		10,198,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	733,000		1,077,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,439,000		3,675,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	904,000		987,000
Non-PCI Loans | With No Recorded Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	34,581,000		32,586,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	858,000		624,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	24,071,000		25,479,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	439,000		472,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	846,000		721,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	271,000		304,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	0		0
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	6,533,000		4,715,000
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	0		263,000
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,483,000		0
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	80,000		8,000
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans which have adverse change in expected cash flows	$438,200,000		$285,600,000

Allowance_for_Loan_and_Lease_L4

Allowance for Loan and Lease Losses (Troubled Debt Restructuring) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
TDRs
Financing Receivable, Modifications [Line Items]
Accruing	$131,466	$135,963
Nonaccruing	25,525	15,516
Financing Receivable, Modifications, Recorded Investment	156,991	151,479
Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	66,046	44,005
Non-PCI Loans | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	86,884	91,316
Nonaccruing	23,526	13,291
Financing Receivable, Modifications, Recorded Investment	110,410	104,607
PCI Loans | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	44,582	44,647
Nonaccruing	1,999	2,225
Financing Receivable, Modifications, Recorded Investment	46,581	46,872
Commercial | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	104,848	107,305
Nonaccruing	17,336	10,861
Financing Receivable, Modifications, Recorded Investment	122,184	118,166
Commercial | Construction and land development | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	3,425	2,591
Nonaccruing	490	446
Financing Receivable, Modifications, Recorded Investment	3,915	3,037
Commercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	1,497	343
Commercial | Mortgage | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	88,889	92,184
Nonaccruing	11,326	8,937
Financing Receivable, Modifications, Recorded Investment	100,215	101,121
Commercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	26,058	24,720
Commercial | Other commercial real estate | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	2,123	2,374
Nonaccruing	423	449
Financing Receivable, Modifications, Recorded Investment	2,546	2,823
Commercial | Other commercial real estate | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	650	619
Commercial | Commercial and industrial | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	9,248	9,864
Nonaccruing	4,768	664
Financing Receivable, Modifications, Recorded Investment	14,016	10,528
Commercial | Commercial and industrial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	5,691	1,741
Commercial | Lease financing | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	1,163	258
Nonaccruing	329	365
Financing Receivable, Modifications, Recorded Investment	1,492	623
Commercial | Lease financing | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	346	374
Commercial | Other | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	0	34
Nonaccruing	0	0
Financing Receivable, Modifications, Recorded Investment	0	34
Noncommerical | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	26,618	28,658
Nonaccruing	8,189	4,655
Financing Receivable, Modifications, Recorded Investment	34,807	33,313
Noncommerical | Mortgage | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	23,060	22,597
Nonaccruing	5,097	4,655
Financing Receivable, Modifications, Recorded Investment	28,157	27,252
Noncommerical | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	19,238	14,242
Noncommerical | Other | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	2,052	1,966
Noncommerical | Construction and land development | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	733	1,391
Nonaccruing	0	0
Financing Receivable, Modifications, Recorded Investment	733	1,391
Noncommerical | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	0	0
Noncommerical | Revolving mortgage | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	1,871	3,675
Nonaccruing	1,112	0
Financing Receivable, Modifications, Recorded Investment	2,983	3,675
Noncommerical | Revolving mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	9,837	0
Noncommerical | Consumer and Other | TDRs
Financing Receivable, Modifications [Line Items]
Accruing	954	995
Nonaccruing	1,980	0
Financing Receivable, Modifications, Recorded Investment	$2,934	$995

Allowance_for_Loan_and_Lease_L5

Allowance for Loan and Lease Losses (Note Restructurings During Period) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	loans	loans
Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	59	61
Financing Receivable, Modifications, Post-Modification Recorded Investment	$11,718	$13,063
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	8	9
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	4,941	1,315
Non-PCI Loans | Interest Only Loan
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	7
Financing Receivable, Modifications, Post-Modification Recorded Investment	3,796	2,253
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	3,796	410
Non-PCI Loans | Loan Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	6	12
Financing Receivable, Modifications, Post-Modification Recorded Investment	770	3,192
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	220	41
Non-PCI Loans | Below Market Interest Rate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	45	28
Financing Receivable, Modifications, Post-Modification Recorded Investment	6,866	5,598
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	4	4
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	778	576
Non-PCI Loans | Discharge of Debt
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	7	14
Financing Receivable, Modifications, Post-Modification Recorded Investment	286	2,020
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	147	288
Non-PCI Loans | Commercial | Interest Only Loan | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	4
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	1,911
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	410
Non-PCI Loans | Commercial | Interest Only Loan | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	3,796	196
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	3,796	0
Non-PCI Loans | Commercial | Interest Only Loan | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	146
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Commercial | Loan Term Extension | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	220	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	220	0
Non-PCI Loans | Commercial | Loan Term Extension | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	3	5
Financing Receivable, Modifications, Post-Modification Recorded Investment	535	2,620
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Commercial | Loan Term Extension | Lease financing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	234
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Commercial | Below Market Interest Rate | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	47	82
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Commercial | Below Market Interest Rate | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	9	12
Financing Receivable, Modifications, Post-Modification Recorded Investment	3,541	4,677
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	733	449
Non-PCI Loans | Commercial | Below Market Interest Rate | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	3	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	172	110
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Commercial | Discharge of Debt | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	1,003
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Loan Term Extension | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	5
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	338
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Loan Term Extension | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	10	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0
Non-PCI Loans | Noncommerical | Loan Term Extension | Consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	5	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	41
Non-PCI Loans | Noncommerical | Below Market Interest Rate | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	23	8
Financing Receivable, Modifications, Post-Modification Recorded Investment	708	451
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2	3
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	45	127
Non-PCI Loans | Noncommerical | Below Market Interest Rate | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	396	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Below Market Interest Rate | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2	5
Financing Receivable, Modifications, Post-Modification Recorded Investment	18	278
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Below Market Interest Rate | Consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	3	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	34	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Below Market Interest Rate | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	1,950	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Discharge of Debt | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	2	7
Financing Receivable, Modifications, Post-Modification Recorded Investment	68	708
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	288
Non-PCI Loans | Noncommerical | Discharge of Debt | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	62
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
Non-PCI Loans | Noncommerical | Discharge of Debt | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	5	4
Financing Receivable, Modifications, Post-Modification Recorded Investment	218	229
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	147	0
Non-PCI Loans | Noncommerical | Discharge of Debt | Consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	18
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	7	9
Financing Receivable, Modifications, Post-Modification Recorded Investment	470	21,765
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	4
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	65	47,718
PCI Loans | Interest Only Loan
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	15,906
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	15,906
PCI Loans | Loan Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	281
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	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	7	6
Financing Receivable, Modifications, Post-Modification Recorded Investment	470	5,578
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	65	31,812
PCI Loans | Commercial | Interest Only Loan | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	2
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	15,906
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	15,906
PCI Loans | Commercial | Loan Term Extension | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	281
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
PCI Loans | Commercial | Below Market Interest Rate | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	37
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	0
PCI Loans | Commercial | Below Market Interest Rate | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	4
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	5,439
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	0	47
PCI Loans | Commercial | Below Market Interest Rate | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	0
Financing Receivable, Modifications, Post-Modification Recorded Investment	0	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	65	0
PCI Loans | Noncommerical | Below Market Interest Rate | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	7	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	470	102
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$0	$436

Other_Real_Estate_Owned_Detail

Other Real Estate Owned (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Real Estate Properties [Line Items]
Financing Receivable in Consumer Mortgage Loans, Collateralized by Residential Real Estate in Process of Foreclosure	$20,100,000			$24,800,000
Covered
Beginning balance	22,982,000	47,081,000	17,302,000		41,855,000
Additions	4,244,000	1,514,000
Sales	-8,970,000	-4,512,000
Writedowns	-954,000	-2,228,000
Noncovered
Beginning balance	70,454,000	36,898,000	72,690,000		44,504,000
Additions	17,084,000	3,318,000
Sales	-13,573,000	-5,854,000
Writedowns	-1,275,000	-1,449,000
Total
Beginning balance	93,436,000	83,979,000
Additions	21,328,000	4,832,000
Sales	-22,543,000	-10,366,000
Writedowns	-2,229,000	-3,677,000
Ending balance	89,992,000	86,359,000
Mortgage
Total
Beginning balance			23,236,000	29,048,000
Ending balance	23,236,000		23,236,000	29,048,000
1st Financial
Covered
Additions		0
Noncovered
Additions		11,591,000
Total
Additions		$11,591,000

Receivable_from_FDIC_for_Loss_2

Receivable from FDIC for Loss Share Agreements (Changes in Receivable from FDIC) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Receivable From FDIC For Loss Share Agreements [Abstract]
FDIC Indemnification Asset	$21,340	$74,784	$28,701	$93,397
Receivable From FDIC For Loss Share Agreements [Roll Forward]
Accretion of discounts and premiums, net	-5,031	-17,744
Receipt of payments from FDIC	5,762	3,490
Post-acquisition and other adjustments, net	($8,092)	($4,359)

Estimated_Fair_Values_Estimate

Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$495,901		$604,182
Overnight investments	2,458,923		1,724,919
Investment securities available for sale	7,045,109		7,171,917
Investment securities held to maturity	441		518
Loans held for sale	66,508		63,696
Loans and Leases Receivable, Net Amount	18,886,204		18,564,999
FDIC Indemnification Asset	21,340		28,701		74,784	93,397
Income earned not collected	63,165		57,254
Mortgage servicing rights	16,436		16,688		0	16
Deposits	26,300,830		25,678,577
FDIC loss share payable	118,645		116,535
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	495,901		604,182
Overnight investments	2,458,923		1,724,919
Investment securities available for sale	7,045,109		7,171,917
Investment securities held to maturity	441		518
Loans held for sale	66,508		63,696
Loans and Leases Receivable, Net Amount	18,886,204		18,564,999
FDIC Indemnification Asset	21,340	[1]	28,701	[1]
Income earned not collected	63,165		57,254
Stock issued by Federal Home Loan Bank	30,291		39,113
Preferred stock and other acquired financial assets	13,689		13,689
Mortgage servicing rights	16,436		16,688
Deposits	26,300,830		25,678,577
Short-term borrowings	941,850		987,184
Long-term obligations	468,180		351,320
FDIC loss share payable	118,645		116,535
Accrued interest payable	8,370		8,194
Interest rate swap	3,761		4,337
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	495,901		604,182
Overnight investments	2,458,923		1,724,919
Investment securities available for sale	7,045,109		7,171,917
Investment securities held to maturity	459		544
Loans held for sale	66,508		63,696
Loans and Leases Receivable, Net Amount	18,359,306		18,046,497
FDIC Indemnification Asset	14,407	[1]	18,218	[1]
Income earned not collected	63,165		57,254
Stock issued by Federal Home Loan Bank	30,291		39,113
Preferred stock and other acquired financial assets	14,688		14,708
Mortgage servicing rights	16,719		16,736
Deposits	25,718,225		25,164,683
Short-term borrowings	941,850		987,184
Long-term obligations	486,960		367,732
FDIC loss share payable	126,113		122,168
Accrued interest payable	8,370		8,194
Interest rate swap	$3,761		$4,337
[1]	The fair value of the FDIC receivable excludes receivable related to accretable yield to be amortized in prospective periods.

Estimated_Fair_Values_Narrativ

Estimated Fair Values (Narrative) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Estimated Fair Values [Line Items]
Total investment securities available for sale, fair value	$7,045,109	$7,171,917
Liability transfers between Level 1 and Level 2	0
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
Fair Value, Measurements, Nonrecurring
Estimated Fair Values [Line Items]
Liability measured at fair value on nonrecurring basis	$0	$0
Minimum
Estimated Fair Values [Line Items]
Discounts for collateral value estimates due to estimated holding and selling costs (percent)	10.00%	10.00%
Maximum
Estimated Fair Values [Line Items]
Discounts for collateral value estimates due to estimated holding and selling costs (percent)	14.00%	14.00%

Estimated_Fair_Values_Assets_A

Estimated Fair Values (Assets And Liabilities Carried At Fair Value On A Recurring Basis) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$7,045,109	$7,171,917
Fair Value, Measurements, Recurring | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	7,045,109	7,171,917
Loans held for sale	66,508	63,696
Interest rate swaps accounted for as cash flow hedges	3,761	4,337
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	0
Loans held for sale	0	0
Interest rate swaps accounted for as cash flow hedges	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	7,045,109	7,171,917
Loans held for sale	66,508	63,696
Interest rate swaps accounted for as cash flow hedges	3,761	4,337
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	0	0
Loans held for sale	0	0
Interest rate swaps accounted for as cash flow hedges	0	0
Fair Value, Measurements, Recurring | U.S. Treasury | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	2,246,966	2,629,670
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	2,246,966	2,629,670
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
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	990,894	908,817
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	990,894	908,817
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, Other [Member] | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,807,249	3,633,304
Fair Value, Measurements, Recurring | Mortgage Backed Securities, Other [Member] | 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, Other [Member] | 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	3,807,249	3,633,304
Fair Value, Measurements, Recurring | Mortgage Backed Securities, Other [Member] | 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 | State, County, Municipal | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale		126
Fair Value, Measurements, Recurring | State, County, Municipal | 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
Fair Value, Measurements, Recurring | State, County, Municipal | 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		126
Fair Value, Measurements, Recurring | State, County, Municipal | 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

Estimated_Fair_Values_Assets_A1

Estimated Fair Values (Assets And Liabilities Carried At Fair Value On A Nonrecurring Basis) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate, Non Covered	$72,690	$70,454	$44,504	$36,898
Other Real Estate, Covered	17,302	22,982	41,855	47,081
Mortgage servicing rights	16,436	16,688	0	16
Fair Value, Measurements, Nonrecurring | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans not covered by loss share agreements	69,749	73,170
Other Real Estate, Non Covered	17,034	40,714
Other Real Estate, Covered	3,714	17,664
Mortgage servicing rights	14,225	13,562
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 not covered by loss share agreements	0	0
Other Real Estate, Non Covered	0	0
Other Real Estate, Covered	0	0
Mortgage servicing rights	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 not covered by loss share agreements	0	0
Other Real Estate, Non Covered	0	0
Other Real Estate, Covered	0	0
Mortgage servicing rights	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 not covered by loss share agreements	69,749	73,170
Other Real Estate, Non Covered	17,034	40,714
Other Real Estate, Covered	3,714	17,664
Mortgage servicing rights	$14,225	$13,562

Estimated_Fair_Values_Estimate1

Estimated Fair Values Estimated Fair Values (Fair Value Option) (Details) (Loans Held For Sale, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Loans Held For Sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Gains (Losses) From Fair Value Changes	$430
Fair Value Of Items For Which Fair Value Option Was Elected Assets	66,508	63,696
Aggregate Unpaid Principal Balance Of Items For Which Fair Value Option Was Elected Assets	65,378	62,996
Fair Value Option Aggregate Difference Assets	$1,130	$700

Employee_Benefit_Plans_Compone

Employee Benefit Plans (Components Of Pension Expense) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
BancShares Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$3,600	$3,381
Interest cost	6,748	6,556
Expected return on assets	-8,295	-7,812
Amortization of prior service cost	53	53
Amortization of net actuarial loss	2,833	1,546
Total pension expense	4,939	3,724
Bancorporation Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	933
Interest cost	1,628
Expected return on assets	-2,869
Amortization of prior service cost	0
Amortization of net actuarial loss	0
Total pension expense	($308)

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Guarantor Obligations [Line Items]
FDIC Indemnification Asset	21,340,000	$28,701,000	$74,784,000	$93,397,000
FDIC loss share payable	118,645,000	116,535,000
Commitments to Extend Credit
Guarantor Obligations [Line Items]
Unused Commitments to Extend Credit	7,570,000,000	7,190,000,000
Affordable housing program obligation	22,600,000	16,800,000
Standby Letters of Credit
Guarantor Obligations [Line Items]
Guarantor obligations amount	75,000,000	77,400,000
Recourse Obligation on Mortgage Loans Sold
Guarantor Obligations [Line Items]
Recourse Period, Maximum1	120 days
Obligation to Repurchase Receivables Sold
Guarantor Obligations [Line Items]
Reserve for estimated losses arising from repurchase of loans	3,100,000	$3,200,000

Derivatives_Narrative_Details

Derivatives (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Derivative [Line Items]
Fair value of collateral pledged to secure interest rate contracts	$7
Incremental interest expense paid to interest rate swap counterparties	0.8	0.8
2011 Interest Rate Swap
Derivative [Line Items]
Notional amount of interest rate derivatives	$93.50
Fixed rate payments, interest rate	5.50%		5.50%
Variable rate payment rate	1.75%		1.75%

Derivatives_Schedule_Of_Intere

Derivatives (Schedule Of Interest Rate Swaps) (Details) (2011 Interest Rate Swap, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
2011 Interest Rate Swap
Derivative [Line Items]
Estimated fair value of liability	$3,761	$4,337
Derivative, Notional Amount	$93,500	$93,500

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014		Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), before Tax	($57,939)				($86,690)
Deferred tax expense (benefit)	-22,528				-33,709
Accumulated other comprehensive income (loss), net of tax	-35,411		-16,594		-52,981		-25,268
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,386		-977
Reclassification adjustment for losses included in income before income taxes	2,886		1,599
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), before Tax	33,632				8,343
Deferred tax expense (benefit)	13,081				3,245
Accumulated other comprehensive income (loss), net of tax	20,551	[1]	-2,835	[1]	5,098	[1]	-10,091	[1]
Income taxes	-1,977
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	3,149	[1]	0	[1]
Funded Status of Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), before Tax	-87,810				-90,696
Deferred tax expense (benefit)	-34,158				-35,281
Accumulated other comprehensive income (loss), net of tax	-53,652	[1]	-9,766	[1]	-55,415	[1]	-10,743	[1]
Income taxes	1,123		622
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	-1,763	[1]	-977	[1]
Employee Benefits, prior service costs	-53		-53
Reclassification adjustment for losses included in income before income taxes	-2,833		-1,546
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	-2,886		-1,599
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), before Tax	-3,761				-4,337
Deferred tax expense (benefit)	-1,451				-1,673
Accumulated other comprehensive income (loss), net of tax	-2,310	[1]	-3,993	[1]	-2,664	[1]	-4,434	[1]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$0	[1]	$0	[1]
[1]	All amounts are net of tax.

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Loss (Components of AOCI) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	($52,981)		($25,268)
Other comprehensive income before reclassifications	18,956		7,697
Amounts reclassified from accumulated other comprehensive (loss) income	-1,386		977
Net current period other comprehensive income	17,570		8,674
Ending balance	-35,411		-16,594
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-2,664	[1]	-4,434	[1]
Other comprehensive income before reclassifications	354	[1]	441	[1]
Amounts reclassified from accumulated other comprehensive (loss) income	0	[1]	0	[1]
Net current period other comprehensive income	354	[1]	441	[1]
Ending balance	-2,310	[1]	-3,993	[1]
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	5,098	[1]	-10,091	[1]
Other comprehensive income before reclassifications	18,602	[1]	7,256	[1]
Amounts reclassified from accumulated other comprehensive (loss) income	-3,149	[1]	0	[1]
Net current period other comprehensive income	15,453	[1]	7,256	[1]
Ending balance	20,551	[1]	-2,835	[1]
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-55,415	[1]	-10,743	[1]
Other comprehensive income before reclassifications	0	[1]	0	[1]
Amounts reclassified from accumulated other comprehensive (loss) income	1,763	[1]	977	[1]
Net current period other comprehensive income	1,763	[1]	977	[1]
Ending balance	($53,652)	[1]	($9,766)	[1]
[1]	All amounts are net of tax.

Accumulated_Other_Comprehensiv4

Accumulated Other Comprehensive Loss (Reclassifications out of AOCI) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Securities gains (losses)	$5,126		$0
Reclassification adjustment for losses included in income before income taxes	2,886		1,599
Amounts reclassified from accumulated other comprehensive income, net of tax	-1,386		977
Unrealized Loss on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income, net of tax	0	[1]	0	[1]
Unrealized Gains on Investment Securities Available for Sale
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Securities gains (losses)	5,126
Income taxes	-1,977
Amounts reclassified from accumulated other comprehensive income, net of tax	-3,149	[1]	0	[1]
Defined Benefit Pension Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Employee Benefits, prior service costs	-53		-53
Reclassification adjustment for losses included in income before income taxes	-2,833		-1,546
Total before taxes	-2,886		-1,599
Income taxes	1,123		622
Amounts reclassified from accumulated other comprehensive income, net of tax	$1,763	[1]	$977	[1]
[1]	All amounts are net of tax.

Repurchase_Agreements_Repurcha2

Repurchase Agreements Repurchase Agreements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	$386,800,000	$418,300,000
Securities Sold under Agreements to Repurchase	365,283,000	324,425,000
Securities Sold under Agreements to Repurchase, Gross	365,283,000	324,425,000
Government Agency
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	6,909,000	6,914,000
U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	358,374,000	186,010,000
Mortgage Backed Securities, Other [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase		131,501,000
Overnight and continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	335,283,000	294,425,000
Overnight and continuous | Government Agency
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	0
Overnight and continuous | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	335,283,000	162,924,000
Overnight and continuous | Mortgage Backed Securities, Other [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase		131,501,000
Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	0
Up to 30 days | Government Agency
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	0
Up to 30 days | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	0
Up to 30 days | Mortgage Backed Securities, Other [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase		0
30 - 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	0	0
30 - 90 days | Government Agency
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	0
30 - 90 days | Mortgage Backed Securities, Other [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase		0
Greater than 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	30,000,000	30,000,000
Greater than 90 days | Government Agency
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	6,909,000	6,914,000
Greater than 90 days | U. S. Treasury
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase	23,091,000	23,086,000
Greater than 90 days | Mortgage Backed Securities, Other [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Sold under Agreements to Repurchase		$0

Mortgage_Servicing_Rights_Mort2

Mortgage Servicing Rights Mortgage Servicing Rights (MSR Carrying Value) ((Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Servicing Asset at Amortized Cost [Line Items]
Mortgage servicing rights	$16,436	$0	$16,688	$16
Amortization of Mortgage Servicing Rights (MSRs)	-852	-164
Servicing Asset at Amortized Cost, Additions	662	0
Valuation Allowance for Impairment of Recognized Servicing Assets, Provisions	62	0
1st Financial
Servicing Asset at Amortized Cost [Line Items]
Servicing Asset at Amortized Cost, Additions	$0	$148

Mortgage_Servicing_Rights_Mort3

Mortgage Servicing Rights Mortgage servicing rights (Valuation allowance) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Mortgage Servicing Rights [Abstract]
Valuation allowance	$912	$0	$850	$0
Valuation allowance provision	($62)	$0

Mortgage_Servicing_Rights_Mort4

Mortgage Servicing Rights Mortgage Servicing Rights (Economic Assumptions) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
	Rate	Rate
Servicing Asset Key Economic Assumptions [Line Items]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed	16.07%	14.25%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Cost to Service Loans	56,020	56,020
Conventional fixed loans
Servicing Asset Key Economic Assumptions [Line Items]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate	6.95%	7.20%
All loans excluding conventional fixed loans
Servicing Asset Key Economic Assumptions [Line Items]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate	8.95%	9.20%

Mortgage_Servicing_Rights_Mort5

Mortgage Servicing Rights Mortgage Servicing Rights (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Mortgage Servicing Rights [Abstract]
Mortgage servicing rights	$16,436,000	$0	$16,688,000	$16,000
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	1,100,000	0
Amortization of Mortgage Servicing Rights (MSRs)	-852,000	-164,000
Valuation allowance provision	($62,000)	$0