F.N.B. (FNB) 10-Q 8 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	FNB
Entity Registrant Name	FNB CORP/FL/
Entity Central Index Key	37808
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		174,693,549

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets
Cash and due from banks	$191,347	$196,240
Interest bearing deposits with banks	42,899	91,153
Cash and Cash Equivalents	234,246	287,393
Securities available for sale	1,537,080	1,534,065
Securities held to maturity (fair value of $1,536,449 and $1,468,258)	1,513,204	1,453,355
Residential mortgage loans held for sale	4,621	6,180
Loans and leases, net of unearned income of $50,916 and $56,131	11,404,099	11,247,038
Allowance for credit losses	-128,499	-125,926
Net Loans and Leases	11,275,600	11,121,112
Premises and equipment, net	169,859	168,756
Goodwill	829,726	832,213
Core deposit and other intangible assets, net	45,520	47,504
Bank owned life insurance	303,102	301,771
Other assets	365,890	374,741
Total Assets	16,278,848	16,127,090
Liabilities
Non-interest bearing demand	2,728,599	2,647,623
Interest bearing demand	4,724,985	4,547,628
Savings	1,763,275	1,575,922
Certificates and other time deposits	2,589,184	2,611,035
Total Deposits	11,806,043	11,382,208
Short-term borrowings	1,740,500	2,041,658
Long-term borrowings	541,474	541,443
Other liabilities	135,555	140,325
Total Liabilities	14,223,572	14,105,634
Stockholders' Equity
Preferred stock - $0.01 par value Authorized - 20,000,000 shares Issued - 110,877 shares	106,882	106,882
Common stock-$0.01 par value Authorized - 500,000,000 shares Issued - 176,305,233 and 175,450,303 shares	1,763	1,754
Additional paid-in capital	1,805,991	1,798,984
Retained earnings	193,461	176,120
Accumulated other comprehensive loss	-34,980	-46,003
Treasury stock - 1,613,531 and 1,458,045 shares at cost	-17,841	-16,281
Total Stockholders' Equity	2,055,276	2,021,456
Total Liabilities and Stockholders' Equity	$16,278,848	$16,127,090

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Securities held to maturity, fair value	$1,536,449	$1,468,258
Unearned income on loans	$50,916	$56,131
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	110,877	110,877
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	176,305,233	175,450,303
Treasury stock, shares	1,613,531	1,458,045

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest Income
Loans and leases, including fees	$117,739	$104,097
Securities:
Taxable	14,214	12,287
Nontaxable	1,373	1,291
Dividends	11	179
Other	32	26
Total Interest Income	133,369	117,880
Interest Expense
Deposits	7,449	7,149
Short-term borrowings	1,768	1,219
Long-term borrowings	2,231	1,687
Total Interest Expense	11,448	10,055
Net Interest Income	121,921	107,825
Provision for credit losses	8,136	7,006
Net Interest Income After Provision for Credit Losses	113,785	100,819
Non-Interest Income
Service charges	15,817	15,269
Trust fees	5,161	4,764
Insurance commissions and fees	4,369	4,945
Securities commissions and fees	3,057	2,391
Net securities (losses) gains	-9	9,461
Mortgage banking operations	1,799	214
Bank owned life insurance	1,843	2,185
Other	6,145	2,841
Total Non-Interest Income	38,182	42,070
Non-Interest Expense
Salaries and employee benefits	49,269	48,953
Net occupancy	8,976	8,482
Equipment	7,648	6,899
Amortization of intangibles	2,115	2,283
Outside services	8,777	7,237
FDIC insurance	3,689	2,994
Merger related		5,318
Other	14,181	12,000
Total Non-Interest Expense	94,655	94,166
Income Before Income Taxes	57,312	48,723
Income taxes	16,969	14,199
Net Income	40,343	34,524
Less: Preferred stock dividends	2,010	2,322
Net Income Available to Common Stockholders	38,333	32,202
Net Income per Common Share - Basic	$0.22	$0.20
Net Income per Common Share - Diluted	$0.22	$0.20
Cash Dividends per Common Share	$0.12	$0.12
Comprehensive income	$51,366	$47,407

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (Unaudited) (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
In Thousands, unless otherwise specified
Balance at Dec. 31, 2013	$1,774,383	$106,882	$1,592	$1,608,117	$121,870	($56,924)	($7,154)
Comprehensive income	47,407				34,524	12,883
Dividends declared:
Preferred stock	-2,322				-2,322
Common stock: $0.12/share	-20,016				-20,016
Issuance of common stock	2,347		12	5,939	-228		-3,376
Issuance of common stock - acquisitions	81,397		67	81,330
Restricted stock compensation	567			567
Tax benefit of stock-based compensation	1,224			1,224
Balance at Mar. 31, 2014	1,884,987	106,882	1,671	1,697,177	133,828	-44,041	-10,530
Balance at Dec. 31, 2014	2,021,456	106,882	1,754	1,798,984	176,120	-46,003	-16,281
Comprehensive income	51,366				40,343	11,023
Dividends declared:
Preferred stock	-2,010				-2,010
Common stock: $0.12/share	-20,992				-20,992
Issuance of common stock	4,435		9	5,986			-1,560
Restricted stock compensation	340			340
Tax benefit of stock-based compensation	681			681
Balance at Mar. 31, 2015	$2,055,276	$106,882	$1,763	$1,805,991	$193,461	($34,980)	($17,841)

Consolidated_Statements_of_Sto1

Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Stockholders' Equity [Abstract]
Common stock dividends per share	$0.12	$0.12

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Activities
Net income	$40,343	$34,524
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	11,725	8,339
Provision for credit losses	8,136	7,006
Deferred tax (benefit) expenses	3,217	-2,154
Net securities losses (gains)	9	-9,461
Tax benefit of stock-based compensation	-681	-1,224
Loans originated for sale	-71,499	-18,245
Loans sold	74,870	22,635
Gain on sale of loans	-1,813	-1,193
Net change in:
Interest receivable	-1,704	-123
Interest payable	-178	-750
Securities classified as trading in business combination and sold		203,178
Bank owned life insurance	-1,323	-1,513
Other, net	5,187	3,096
Net cash flows provided by operating activities	66,289	244,115
Investing Activities
Net change in loans and leases	-167,685	-140,938
Securities available for sale:
Purchases	-90,156	-318,332
Sales	33,228	85,877
Maturities	66,275	130,641
Securities held to maturity:
Purchases	-130,506	-266,486
Maturities	69,394	44,159
Purchase of bank owned life insurance	-8	-4,433
Withdrawal/surrender of bank owned life insurance		716
Increase in premises and equipment	-6,199	-6,042
Net cash received in business combinations		26,964
Net cash flows used in investing activities	-225,657	-447,874
Financing Activities
Demand (non-interest bearing and interest bearing) and savings accounts	445,685	253,935
Time deposits	-20,779	-44,043
Short-term borrowings	-301,158	-24,615
Increase in long-term borrowings	6,598	108,079
Decrease in long-term borrowings	-6,579	-39,966
Net proceeds from issuance of common stock	4,775	3,755
Tax benefit of stock-based compensation	681	1,224
Cash dividends paid:
Preferred stock	-2,010	-2,322
Common stock	-20,992	-20,016
Net cash flows provided by financing activities	106,221	236,031
Net (Decrease) Increase in Cash and Cash Equivalents	-53,147	32,272
Cash and cash equivalents at beginning of period	287,393	213,981
Cash and Cash Equivalents at End of Period	$234,246	$246,253

Business

Business	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Business	BUSINESS
	F.N.B. Corporation (the Corporation), headquartered in Pittsburgh, Pennsylvania, is a diversified financial services company operating in six states and three major metropolitan areas, including Pittsburgh, Baltimore, Maryland and Cleveland, Ohio. As of March 31, 2015, the Corporation had 287 banking offices throughout Pennsylvania, Ohio, Maryland and West Virginia. The Corporation provides a full range of commercial banking, consumer banking and wealth management solutions through its subsidiary network which is led by its largest affiliate, First National Bank of Pennsylvania (FNBPA). Commercial banking solutions include corporate banking, small business banking, investment real estate financing, international banking, business credit, capital markets and lease financing. Consumer banking provides a full line of consumer banking products and services including deposit products, mortgage lending, consumer lending and a complete suite of mobile and online banking services. Wealth management services include asset management, private banking and insurance. The Corporation also operates Regency Finance Company (Regency), which had 73 consumer finance offices in Pennsylvania, Ohio, Kentucky and Tennessee as of March 31, 2015.

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION
	The Corporation’s accompanying consolidated financial statements and these notes to the financial statements include subsidiaries in which the Corporation has a controlling financial interest. The Corporation owns and operates FNBPA, First National Trust Company, First National Investment Services Company, LLC, F.N.B. Investment Advisors, Inc., First National Insurance Agency, LLC, Regency, Bank Capital Services, LLC and F.N.B. Capital Corporation, LLC, and includes results for each of these entities in the accompanying consolidated financial statements.
	The accompanying consolidated financial statements include all adjustments that are necessary, in the opinion of management, to fairly reflect the Corporation’s financial position and results of operations in accordance with U.S. generally accepted accounting principles (GAAP). All significant intercompany balances and transactions have been eliminated. Certain prior period amounts have been reclassified to conform to the current period presentation. Events occurring subsequent to the date of the balance sheet have been evaluated for potential recognition or disclosure in the consolidated financial statements through the date of the filing of the consolidated financial statements with the Securities and Exchange Commission (SEC).
	Certain information and note disclosures normally included in consolidated financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. The interim operating results are not necessarily indicative of operating results the Corporation expects for the full year. These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Corporation’s Annual Report on Form 10-K filed with the SEC on February 27, 2015.

Use_of_Estimates

Use of Estimates	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Use of Estimates	USE OF ESTIMATES
	The accounting and reporting policies of the Corporation conform with GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could materially differ from those estimates. Material estimates that are particularly susceptible to significant changes include the allowance for credit losses, securities valuations, goodwill and other intangible assets and income taxes.

Mergers_and_Acquisitions

Mergers and Acquisitions	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Mergers and Acquisitions	MERGERS AND ACQUISITIONS
	OBA Financial Services, Inc.
	On September 19, 2014, the Corporation completed its acquisition of OBA Financial Services, Inc. (OBA), a bank holding company based in Germantown, Maryland. On the acquisition date, the estimated fair values of OBA included $390,128 in assets, $291,393 in loans and $295,922 in deposits. The acquisition was valued at approximately $85,554 and resulted in the Corporation issuing 7,170,037 shares of its common stock in exchange for 4,025,895 shares of OBA common stock. The Corporation also acquired the outstanding stock options of OBA that became fully vested upon the acquisition. The assets and liabilities of OBA were recorded on the Corporation’s consolidated balance sheet at their preliminary estimated fair values as of September 19, 2014, the acquisition date, and OBA’s results of operations have been included in the Corporation’s consolidated statement of comprehensive income since that date. OBA’s banking affiliate, OBA Bank, was merged into FNBPA on September 19, 2014. Based on a preliminary purchase price allocation, the Corporation recorded $20,139 in goodwill and $4,304 in core deposit intangibles as a result of the acquisition. These fair value estimates are provisional amounts based on third party valuations that are currently under review. None of the goodwill is deductible for income tax purposes.
	BCSB Bancorp, Inc.
	On February 15, 2014, the Corporation completed its acquisition of BCSB Bancorp, Inc. (BCSB), a bank holding company based in Baltimore, Maryland. On the acquisition date, the estimated fair values of BCSB included $596,122 in assets, $304,932 in loans and $532,197 in deposits. The acquisition was valued at $80,547 and resulted in the Corporation issuing 6,730,597 shares of its common stock in exchange for 3,235,961 shares of BCSB common stock. The Corporation also acquired the outstanding stock options of BCSB that became fully vested upon the acquisition. The assets and liabilities of BCSB were recorded on the Corporation’s consolidated balance sheet at their fair values as of February 15, 2014, the acquisition date, and BCSB’s results of operations have been included in the Corporation’s consolidated statement of comprehensive income since that date. BCSB’s banking affiliate, Baltimore County Savings Bank, was merged into FNBPA on February 15, 2014. Based on the purchase price allocation, the Corporation recorded $42,451 in goodwill and $6,591 in core deposit intangibles as a result of the acquisition. None of the goodwill is deductible for income tax purposes.

New_Accounting_Standards

New Accounting Standards	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards	NEW ACCOUNTING STANDARDS
	Cloud Computing Arrangements
	In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-05, Intangibles-Goodwill and Other-Internal-Use Software. ASU 2015-05 provides guidance to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement environment. The amendments in this Update provide a basis for evaluating whether a cloud computing arrangement includes a software license to internal-use software, and how to account for the software license element of the arrangement. This update supersedes the existing requirement to analogize to operating lease guidance in accounting for some software licenses. The requirements of ASU 2015-05 are effective for reporting periods beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply ASU 2015-05 either prospectively or retrospectively. The Corporation is evaluating this new guidance and has not yet determined which approach it will adopt to apply the amendments in ASU 2015-05 or the impact that the adoption of this update will have on its financial statements.
	Consolidation
	In February 2015, the FASB issued ASU No. 2015-02, Consolidation. ASU 2015-02 changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. This update modifies the evaluation of whether limited partnerships or similar legal entities are variable interest entities (VIEs) or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership and affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The requirements of ASU 2015-02 are effective for reporting periods beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply ASU 2015-02 either retrospectively or by using a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption. The adoption of this update is not expected to have a material effect on the financial statements, results of operations or liquidity of the Corporation.
	Income Statement
	In January 2015, the FASB issued ASU No. 2015-01, Income Statement – Extraordinary and Unusual Items. The FASB issued ASU 2015-01 as part of its Simplification Initiative to reduce complexity in accounting standards. ASU 2015-01 eliminates from GAAP the concept of extraordinary items. The requirements of ASU 2015-01 are effective for reporting periods beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply ASU 2015-01 prospectively, or retrospectively to all prior periods presented in the financial statements. The adoption of this update will not have an effect on the financial statements, results of operations or liquidity of the Corporation, as the Corporation has not reported extraordinary items.

Securities

Securities	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Securities	SECURITIES
	The amortized cost and fair value of securities are as follows:
		Amortized			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized
					Gains			Losses
	Securities Available for Sale
	March 31, 2015
	U.S. Treasury	$	29,637		$	300		$	—		$	29,937
	U.S. government-sponsored entities		388,363			2,818			(521	)		390,660
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		494,497			11,064			—			505,561
	Agency collateralized mortgage obligations		573,738			3,646			(5,367	)		572,017
	Non-agency collateralized mortgage obligations		1,359			5			—			1,364
	Commercial mortgage-backed securities		6,844			—			(1	)		6,843
	States of the U.S. and political subdivisions		12,713			476			(14	)		13,175
	Other debt securities		16,643			373			(785	)		16,231
	Total debt securities		1,523,794			18,682			(6,688	)		1,535,788
	Equity securities		1,031			261			—			1,292
		$	1,524,825		$	18,943		$	(6,688	)	$	1,537,080
	December 31, 2014
	U.S. Treasury	$	29,604		$	78		$	—		$	29,682
	U.S. government-sponsored entities		338,330			742			(1,939	)		337,133
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		546,572			7,548			(35	)		554,085
	Agency collateralized mortgage obligations		580,601			1,617			(9,047	)		573,171
	Non-agency collateralized mortgage obligations		1,414			17			—			1,431
	Commercial mortgage-backed securities		7,891			—			(11	)		7,880
	States of the U.S. and political subdivisions		12,713			477			(32	)		13,158
	Other debt securities		16,615			420			(857	)		16,178
	Total debt securities		1,533,740			10,899			(11,921	)		1,532,718
	Equity securities		1,031			316			—			1,347
		$	1,534,771		$	11,215		$	(11,921	)	$	1,534,065
	Securities Held to Maturity
	March 31, 2015
	U.S. Treasury	$	500		$	182		$	—		$	682
	U.S. government-sponsored entities		146,578			1,731			(149	)		148,160
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		674,101			19,130			(20	)		693,211
	Agency collateralized mortgage obligations		505,859			3,633			(4,884	)		504,608
	Non-agency collateralized mortgage obligations		3,840			21			—			3,861
	Commercial mortgage-backed securities		17,484			385			—			17,869
	States of the U.S. and political subdivisions		164,842			3,372			(156	)		168,058
		$	1,513,204		$	28,454		$	(5,209	)	$	1,536,449
	December 31, 2014
	U.S. Treasury	$	502		$	168		$	—		$	670
	U.S. government-sponsored entities		101,602			885			(524	)		101,963
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		677,169			16,712			(346	)		693,535
	Agency collateralized mortgage obligations		501,965			1,858			(7,329	)		496,494
	Non-agency collateralized mortgage obligations		4,285			28			—			4,313
	Commercial mortgage-backed securities		17,560			179			—			17,739
	States of the U.S. and political subdivisions		150,272			3,315			(43	)		153,544
		$	1,453,355		$	23,145		$	(8,242	)	$	1,468,258
	The Corporation classifies securities as trading securities when management intends to sell such securities in the near term. Such securities are carried at fair value, with unrealized gains (losses) reflected through the consolidated statements of comprehensive income. The Corporation classified certain securities acquired in conjunction with its acquisitions as trading securities. The Corporation both acquired and sold these trading securities during the quarterly periods in which each of the acquisitions occurred. As of March 31, 2015 and December 31, 2014, the Corporation did not hold any trading securities.
	Gross gains and gross losses were realized on securities as follows:
		Three Months Ended
		March 31,
		2015			2014
	Gross gains	$	—		$	18,009
	Gross losses		(9	)		(8,548	)
		$	(9	)	$	9,461
	During the first quarter of 2014, the Corporation strategically sold its entire portfolio of pooled trust preferred securities (TPS) with net proceeds of $51,540 and a gain of $13,766. These were previously classified as collateralized debt obligations (CDOs) available for sale. Of the 23 pooled securities sold, one was determined to be a disallowed investment under the Volcker Rule (Section 619) of the Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank Act), and as such, was required to be disposed of by July 2015. Partially offsetting this gain was a net loss of $4,305 relating to the sale of other securities. By selling these securities, the Corporation strengthened the risk profile of its investment portfolio, improved its capital levels due to lowered risk-weighted assets and generated capital to support future growth.
	As of March 31, 2015, the amortized cost and fair value of securities, by contractual maturities, were as follows:
		Available for Sale						Held to Maturity
	Amortized			Fair			Amortized			Fair
	Cost			Value			Cost			Value
Due in one year or less	$	4,985		$	5,069		$	1,282		$	1,285
Due from one to five years		423,890			426,811			138,269			139,139
Due from five to ten years		11,591			12,018			72,457			74,672
Due after ten years		6,890			6,105			99,912			101,804
		447,356			450,003			311,920			316,900
Residential mortgage-backed securities:
Agency mortgage-backed securities		494,497			505,561			674,101			693,211
Agency collateralized mortgage obligations		573,738			572,017			505,859			504,608
Non-agency collateralized mortgage obligations		1,359			1,364			3,840			3,861
Commercial mortgage-backed securities		6,844			6,843			17,484			17,869
Equity securities		1,031			1,292			—			—
	$	1,524,825		$	1,537,080		$	1,513,204		$	1,536,449
Maturities may differ from contractual terms because borrowers may have the right to call or prepay obligations with or without penalties. Periodic payments are received on mortgage-backed securities based on the payment patterns of the underlying collateral.
At March 31, 2015 and December 31, 2014, securities with a carrying value of $1,315,565 and $1,036,380, respectively, were pledged to secure public deposits, trust deposits and for other purposes as required by law. Securities with a carrying value of $807,261 and $892,647 at March 31, 2015 and December 31, 2014, respectively, were pledged as collateral for short-term borrowings.
Following are summaries of the fair values and unrealized losses of securities, segregated by length of impairment:
	Less than 12 Months									12 Months or More							Total
	#			Fair			Unrealized			#		Fair		Unrealized			#		Fair		Unrealized
				Value			Losses					Value		Losses					Value		Losses
Securities Available for Sale
March 31, 2015
U.S. government-sponsored entities		3		$	59,857		$	(142	)		5	$	55,612	$	(379	)		8	$	115,469	$	(521	)
Residential mortgage-backed securities:
Agency collateralized mortgage obligations		4			61,998			(199	)		17		242,124		(5,168	)		21		304,122		(5,367	)
Commercial mortgage-backed securities		1			6,843			(1	)		—		—		—			1		6,843		(1	)
States of the U.S. and political subdivisions		—			—			—			1		1,177		(14	)		1		1,177		(14	)
Other debt securities		—			—			—			4		6,105		(785	)		4		6,105		(785	)
		8		$	128,698		$	(342	)		27	$	305,018	$	(6,346	)		35	$	433,716	$	(6,688	)
December 31, 2014
U.S. government-sponsored entities		7		$	89,986		$	(275	)		7	$	99,326	$	(1,664	)		14	$	189,312	$	(1,939	)
Residential mortgage-backed securities:
Agency mortgage-backed securities		2			45,145			(35	)		—		—		—			2		45,145		(35	)
Agency collateralized mortgage obligations		9			166,908			(1,238	)		16		225,700		(7,809	)		25		392,608		(9,047	)
Commercial mortgage-backed securities		1			7,880			(11	)		—		—		—			1		7,880		(11	)
States of the U.S. and political subdivisions		—			—			—			1		1,159		(32	)		1		1,159		(32	)
Other debt securities		—			—			—			4		6,030		(857	)		4		6,030		(857	)
		19		$	309,919		$	(1,559	)		28	$	332,215	$	(10,362	)		47	$	642,134	$	(11,921	)
Securities Held to Maturity
March 31, 2015
U.S. government-sponsored entities		1		$	14,970		$	(30	)		1	$	14,881	$	(119	)		2	$	29,851	$	(149	)
Residential mortgage-backed securities:
Agency mortgage-backed securities		—			—			—			1		1,234		(20	)		1		1,234		(20	)
Agency collateralized mortgage obligations		4			69,926			(402	)		14		185,466		(4,482	)		18		255,392		(4,884	)
States of the U.S. and political subdivisions		8			13,418			(156	)		—		—		—			8		13,418		(156	)
		13		$	98,314		$	(588	)		16	$	201,581	$	(4,621	)		29	$	299,895	$	(5,209	)
December 31, 2014
U.S. government-sponsored entities		2		$	24,989		$	(40	)		2	$	29,516	$	(484	)		4	$	54,505	$	(524	)
Residential mortgage-backed securities:
Agency mortgage-backed securities		1			1,099			(1	)		4		45,042		(345	)		5		46,141		(346	)
Agency collateralized mortgage obligations		8			104,071			(630	)		14		189,642		(6,699	)		22		293,713		(7,329	)
States of the U.S. and political subdivisions		1			1,427			(4	)		4		5,453		(39	)		5		6,880		(43	)
		12		$	131,586		$	(675	)		24	$	269,653	$	(7,567	)		36	$	401,239	$	(8,242	)
The Corporation does not intend to sell the debt securities and it is not more likely than not the Corporation will be required to sell the securities before recovery of their amortized cost basis.
The Corporation’s remaining portfolio of TPS consists of four single-issuer securities, which are primarily from money-center and large regional banks and are included in other debt securities. These TPS had an amortized cost and estimated fair value of $6,890 and $6,105 at March 31, 2015, respectively. The Corporation has concluded from its analysis performed at March 31, 2015 that it is probable that the Corporation will collect all contractual principal and interest payments related to these securities.
Other-Than-Temporary Impairment
The Corporation evaluates its investment securities portfolio for other-than-temporary impairment (OTTI) on a quarterly basis. Impairment is assessed at the individual security level. The Corporation considers an investment security impaired if the fair value of the security is less than its cost or amortized cost basis. The following table presents a summary of the cumulative credit-related OTTI charges recognized as components of earnings for securities for which a portion of an OTTI is recognized in other comprehensive income:
	Collateralized			Equities			Total
	Debt
	Obligations
For the Three Months Ended March 31, 2015
Beginning balance		—		$	27		$	27
Loss where impairment was not previously recognized		—			—			—
Additional loss where impairment was previously recognized		—			—			—
Reduction due to credit impaired securities sold		—			—			—
Ending balance		—		$	27		$	27
For the Three Months Ended March 31, 2014
Beginning balance	$	17,155		$	27		$	17,182
Loss where impairment was not previously recognized		—			—			—
Additional loss where impairment was previously recognized		—			—			—
Reduction due to credit impaired securities sold		(17,155	)		—			(17,155	)
Ending balance	$	—		$	27		$	27
The Corporation did not recognize any impairment losses on securities for the three months ended March 31, 2015 or 2014.
States of the U.S. and Political Subdivisions
The Corporation’s municipal bond portfolio of $178,017 as of March 31, 2015 is highly rated with an average entity-specific rating of AA and 99.0% of the portfolio rated A or better. General obligation bonds comprise 99.5% of the portfolio. Geographically, municipal bonds support the Corporation’s primary footprint as 89.9% of the securities are from municipalities located throughout Pennsylvania, Ohio and Maryland. The average holding size of the securities in the municipal bond portfolio is $1,203. In addition to the strong stand-alone ratings, 88.0% of the municipalities have some formal credit enhancement insurance that strengthens the creditworthiness of their issue. Management also reviews the credit profile of each issuer on a quarterly basis.

Federal_Home_Loan_Bank_Stock

Federal Home Loan Bank Stock	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Federal Home Loan Bank Stock	FEDERAL HOME LOAN BANK STOCK
	The Corporation is a member of the Federal Home Loan Bank (FHLB) of Pittsburgh. The FHLB requires members to purchase and hold a specified minimum level of FHLB stock based upon their level of borrowings, collateral balances and participation in other programs offered by the FHLB. Stock in the FHLB is non-marketable and is redeemable at the discretion of the FHLB. Both cash and stock dividends on FHLB stock are reported as income.
	Members do not purchase stock in the FHLB for the same reasons that traditional equity investors acquire stock in an investor-owned enterprise. Rather, members purchase stock to obtain access to the low-cost products and services offered by the FHLB. Unlike equity securities of traditional for-profit enterprises, the stock of FHLB does not provide its holders with an opportunity for capital appreciation because, by regulation, FHLB stock can only be purchased, redeemed and transferred at par value.
	At March 31, 2015 and December 31, 2014, the Corporation’s FHLB stock totaled $42,000 and $54,751, respectively, and is included in other assets on the balance sheet. The Corporation accounts for the stock in accordance with ASC 325, which requires the investment to be carried at cost and evaluated for impairment based on the ultimate recoverability of the par value. Due to the continued improvement of the FHLB’s financial performance and stability over the past several years, along with a special dividend during the first quarter of 2015 and quarterly cash dividends in 2014 and the first quarter of 2015, the Corporation believes its holdings in the stock are ultimately recoverable at par value and, therefore, determined that FHLB stock was not other-than-temporarily impaired. In addition, the Corporation has ample liquidity and does not require redemption of its FHLB stock in the foreseeable future.

Loans_and_Leases

Loans and Leases	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Loans and Leases	LOANS AND LEASES
	Following is a summary of loans and leases, net of unearned income:
			Originated			Acquired			Total
			Loans			Loans			Loans and
									Leases
	March 31, 2015
	Commercial real estate		$	3,082,385		$	734,804		$	3,817,189
	Commercial and industrial			2,281,075			116,656			2,397,731
	Commercial leases			180,207			—			180,207
	Total commercial loans and leases			5,543,667			851,460			6,395,127
	Direct installment			1,594,846			58,775			1,653,621
	Residential mortgages			877,437			421,660			1,299,097
	Indirect installment			903,780			1,424			905,204
	Consumer lines of credit			953,569			154,849			1,108,418
	Other			42,632			—			42,632
			$	9,915,931		$	1,488,168		$	11,404,099
	December 31, 2014
	Commercial real estate		$	3,031,810		$	783,898		$	3,815,708
	Commercial and industrial			2,197,793			120,222			2,318,015
	Commercial leases			177,824			—			177,824
	Total commercial loans and leases			5,407,427			904,120			6,311,547
	Direct installment			1,579,770			64,851			1,644,621
	Residential mortgages			817,586			445,467			1,263,053
	Indirect installment			873,645			1,906			875,551
	Consumer lines of credit			946,427			164,549			1,110,976
	Other			41,290			—			41,290
			$	9,666,145		$	1,580,893		$	11,247,038
	Commercial real estate includes both owner-occupied and non-owner-occupied loans secured by commercial properties. Commercial and industrial includes loans to businesses that are not secured by real estate. Commercial leases are made for new or used equipment. Direct installment is comprised of fixed-rate, closed-end consumer loans for personal, family or household use, such as home equity loans and automobile loans. Residential mortgages consist of conventional and jumbo mortgage loans for non-commercial properties. Indirect installment is comprised of loans originated by third parties and underwritten by the Corporation, primarily automobile loans. Consumer lines of credit include home equity lines of credit (HELOC) and consumer lines of credit that are either unsecured or secured by collateral other than home equity. Other is comprised primarily of credit cards, mezzanine loans and student loans.
	The loan and lease portfolio consists principally of loans to individuals and small- and medium-sized businesses within the Corporation’s primary market area of Pennsylvania, eastern Ohio, Maryland and northern West Virginia. The total loan portfolio contains consumer finance loans to individuals in Pennsylvania, Ohio, Tennessee and Kentucky, which totaled $174,239 or 1.5% of total loans and leases at March 31, 2015, compared to $180,588 or 1.6% of total loans and leases at December 31, 2014. Due to the relative size of the consumer finance loan portfolio, they are not segregated from other consumer loans.
	As of March 31, 2015, 40.8% of the commercial real estate loans were owner-occupied, while the remaining 59.2% were non-owner-occupied, compared to 41.6% and 58.4%, respectively, as of December 31, 2014. As of March 31, 2015 and December 31, 2014, the Corporation had commercial construction loans of $227,179 and $296,156, respectively, representing 2.0% and 2.6% of total loans and leases at those respective dates.
	Acquired Loans
	All acquired loans were initially recorded at fair value at the acquisition date. The outstanding balance and the carrying amount of acquired loans included in the consolidated balance sheet are as follows:
			March 31,			December 31,
			2015			2014
	Accounted for under ASC 310-30:
	Outstanding balance		$	1,513,616		$	1,597,558
	Carrying amount			1,259,995			1,344,171
	Accounted for under ASC 310-20:
	Outstanding balance			232,524			242,488
	Carrying amount			220,921			228,748
	Total acquired loans:
	Outstanding balance			1,746,140			1,840,046
	Carrying amount			1,480,916			1,572,919
	The carrying amount of purchased credit impaired loans included in the table above totaled $7,100 at March 31, 2015 and $9,556 at December 31, 2014, representing less than 1% of the carrying amount of total acquired loans as of each date.
	The following table provides changes in accretable yield for all acquired loans accounted for under ASC 310-30. Loans accounted for under ASC 310-20 are not included in this table.
			Three Months Ended
			March 31,
			2015			2014
	Balance at beginning of period		$	331,899		$	305,646
	Reduction due to unexpected early payoffs			(11,909	)		(12,694	)
	Reclass from non-accretable difference			7,676			768
	Disposals/transfers			(118	)		(944	)
	Accretion			(16,264	)		(15,913	)
	Balance at end of period		$	311,284		$	276,863
	Credit Quality
	Management monitors the credit quality of the Corporation’s loan and lease portfolio on an ongoing basis. Measurement of delinquency and past due status is based on the contractual terms of each loan.
	Non-performing loans include non-accrual loans and non-performing troubled debt restructurings (TDRs). Past due loans are reviewed on a monthly basis to identify loans for non-accrual status. The Corporation places a loan on non-accrual status and discontinues interest accruals on originated loans generally when principal or interest is due and has remained unpaid for a certain number of days unless the loan is both well secured and in the process of collection. Commercial loans are placed on non-accrual at 90 days, installment loans are placed on non-accrual at 120 days and residential mortgages and consumer lines of credit are generally placed on non-accrual at 180 days. When a loan is placed on non-accrual status, all unpaid interest is reversed. Non-accrual loans may not be restored to accrual status until all delinquent principal and interest have been paid and the ultimate ability to collect the remaining principal and interest is reasonably assured. TDRs are loans in which the borrower has been granted a concession on the interest rate or the original repayment terms due to financial distress.
	Following is a summary of non-performing assets:
			March 31,			December 31,
			2015			2014
	Non-accrual loans		$	45,029		$	45,113
	Troubled debt restructurings			22,022			23,439
	Total non-performing loans			67,051			68,552
	Other real estate owned (OREO)			40,796			41,466
Total non-performing assets		$	107,847		$	110,018
Asset quality ratios:
Non-performing loans as a percent of total loans and leases			0.59	%		0.61	%
Non-performing loans + OREO as a percent of total loans and leases + OREO			0.94	%		0.97	%
Non-performing assets as a percent of total assets			0.66	%		0.68	%
The carrying value of residential OREO held as a result of obtaining physical possession upon completion of a foreclosure or through completion of a deed in lieu of foreclosure amounted to $3,541 at March 31, 2015. Also, the recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process at March 31, 2015 amounted to $14,186.
The following tables provide an analysis of the aging of the Corporation’s past due loans by class, segregated by loans and leases originated and loans acquired:
		30-89 Days			> 90 Days			Non-Accrual		Total		Current			Total
		Past Due			Past Due and					Past Due					Loans and
					Still Accruing										Leases
Originated Loans and Leases
March 31, 2015
Commercial real estate		$	6,655		$	130		$	23,653	$	30,438	$	3,051,947		$	3,082,385
Commercial and industrial			2,939			3			8,846		11,788		2,269,287			2,281,075
Commercial leases			1,097			—			732		1,829		178,378			180,207
Total commercial loans and leases			10,691			133			33,231		44,055		5,499,612			5,543,667
Direct installment			8,748			3,575			6,464		18,787		1,576,059			1,594,846
Residential mortgages			7,040			1,731			3,625		12,396		865,041			877,437
Indirect installment			5,015			409			1,111		6,535		897,245			903,780
Consumer lines of credit			2,501			656			598		3,755		949,814			953,569
Other			47			39			—		86		42,546			42,632
		$	34,042		$	6,543		$	45,029	$	85,614	$	9,830,317		$	9,915,931
December 31, 2014
Commercial real estate		$	9,601		$	313		$	24,132	$	34,046	$	2,997,764		$	3,031,810
Commercial and industrial			2,446			3			8,310		10,759		2,187,034			2,197,793
Commercial leases			961			43			722		1,726		176,098			177,824
Total commercial loans and leases			13,008			359			33,164		46,531		5,360,896			5,407,427
Direct installment			9,333			3,617			7,117		20,067		1,559,703			1,579,770
Residential mortgages			8,709			3,891			2,964		15,564		802,022			817,586
Indirect installment			7,804			684			1,149		9,637		864,008			873,645
Consumer lines of credit			2,408			562			719		3,689		942,738			946,427
Other			13			135			—		148		41,142			41,290
		$	41,275		$	9,248		$	45,113	$	95,636	$	9,570,509		$	9,666,145
		30-89			> 90 Days			Total		Current		Discount			Total
		Days			Past Due			Past							Loans
		Past Due			and Still			Due (1) (2)
					Accruing
Acquired Loans
March 31, 2015
Commercial real estate		$	8,813		$	12,445		$	21,258	$	753,073	$	(39,527	)	$	734,804
Commercial and industrial			1,023			1,651			2,674		122,604		(8,622	)		116,656
Total commercial loans			9,836			14,096			23,932		875,677		(48,149	)		851,460
Direct installment			1,199			1,112			2,311		55,476		988			58,775
Residential mortgages			7,695			18,535			26,230		434,061		(38,631	)		421,660
Indirect installment			9			17			26		1,648		(250	)		1,424
Consumer lines of credit			1,115			2,146			3,261		156,676		(5,088	)		154,849
		$	19,854		$	35,906		$	55,760	$	1,523,538	$	(91,130	)	$	1,488,168
December 31, 2014
Commercial real estate		$	12,076		$	12,368		$	24,444	$	799,991	$	(40,537	)	$	783,898
Commercial and industrial			687			1,968			2,655		127,535		(9,968	)		120,222
Total commercial loans			12,763			14,336			27,099		927,526		(50,505	)		904,120
Direct installment			2,670			1,443			4,113		59,532		1,206			64,851
Residential mortgages			8,159			19,936			28,095		456,810		(39,438	)		445,467
Indirect installment			38			30			68		2,179		(341	)		1,906
Consumer lines of credit			1,048			2,279			3,327		166,912		(5,690	)		164,549
		$	24,678		$	38,024		$	62,702	$	1,612,959	$	(94,768	)	$	1,580,893
-1	Past due information for acquired loans is based on the contractual balance outstanding at March 31, 2015 and December 31, 2014.
-2	Acquired loans are considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if the Corporation can reasonably estimate the timing and amount of expected cash flows on such loans. Accordingly, the Corporation does not consider acquired contractually delinquent loans to be non-accrual or non-performing and continues to recognize interest income on these loans using the accretion method.
The Corporation utilizes the following categories to monitor credit quality within its commercial loan and lease portfolio:
Rating Category		Definition
Pass		in general, the condition and performance of the borrower is satisfactory or better
Special Mention		in general, the condition of the borrower has deteriorated, requiring an increased level of monitoring
Substandard		in general, the condition and performance of the borrower has significantly deteriorated and could further deteriorate if deficiencies are not corrected
Doubtful		in general, the condition of the borrower has significantly deteriorated and the collection in full
		of both principal and interest is highly questionable or improbable
The use of these internally assigned credit quality categories within the commercial loan and lease portfolio permits management’s use of transition matrices to estimate a quantitative portion of credit risk. The Corporation’s internal credit risk grading system is based on past experiences with similarly graded loans and leases and conforms with regulatory categories. In general, loan and lease risk ratings within each category are reviewed on an ongoing basis according to the Corporation’s policy for each class of loans and leases. Each quarter, management analyzes the resulting ratings, as well as other external statistics and factors such as delinquency, to track the migration performance of the commercial loan and lease portfolio. Loans and leases within the Pass credit category or that migrate toward the Pass credit category generally have a lower risk of loss compared to loans and leases that migrate toward the Substandard or Doubtful credit categories. Accordingly, management applies higher risk factors to Substandard and Doubtful credit categories.
The following tables present a summary of the Corporation’s commercial loans and leases by credit quality category, segregated by loans and leases originated and loans acquired:
		Commercial Loan and Lease Credit Quality Categories
		Pass			Special			Substandard		Doubtful		Total
					Mention
Originated Loans and Leases
March 31, 2015
Commercial real estate		$	2,960,542		$	52,926		$	68,182	$	735	$	3,082,385
Commercial and industrial			2,190,066			53,482			36,081		1,446		2,281,075
Commercial leases			177,091			2,222			894		—		180,207
		$	5,327,699		$	108,630		$	105,157	$	2,181	$	5,543,667
December 31, 2014
Commercial real estate		$	2,890,830		$	58,630		$	81,951	$	399	$	3,031,810
Commercial and industrial			2,085,893			71,420			39,684		796		2,197,793
Commercial leases			174,677			2,198			949		—		177,824
		$	5,151,400		$	132,248		$	122,584	$	1,195	$	5,407,427
Acquired Loans
March 31, 2015
Commercial real estate		$	579,462		$	64,892		$	90,450		—	$	734,804
Commercial and industrial			102,974			2,411			11,271		—		116,656
		$	682,436		$	67,303		$	101,721		—	$	851,460
December 31, 2014
Commercial real estate		$	610,260		$	73,891		$	99,747		—	$	783,898
Commercial and industrial			103,862			3,506			12,854		—		120,222
		$	714,122		$	77,397		$	112,601		—	$	904,120
Credit quality information for acquired loans is based on the contractual balance outstanding at March 31, 2015 and December 31, 2014.
The Corporation uses delinquency transition matrices within the consumer and other loan classes to enable management to estimate a quantitative portion of credit risk. Each month, management analyzes payment and volume activity, FICO scores and other external factors such as unemployment, to determine how consumer loans are performing.
Following is a table showing originated consumer loans by payment status:
		Consumer Loan Credit Quality
		by Payment Status
		Performing			Non-Performing			Total
March 31, 2015
Direct installment		$	1,581,078		$	13,768		$	1,594,846
Residential mortgages			862,965			14,472			877,437
Indirect installment			902,515			1,265			903,780
Consumer lines of credit			951,980			1,589			953,569
Other			42,632			—			42,632
December 31, 2014
Direct installment		$	1,565,090		$	14,680		$	1,579,770
Residential mortgages			802,522			15,064			817,586
Indirect installment			872,340			1,305			873,645
Consumer lines of credit			944,631			1,796			946,427
Other			41,290			—			41,290
Loans and leases are designated as impaired when, in the opinion of management, based on current information and events, the collection of principal and interest in accordance with the loan and lease contract is doubtful. Typically, the Corporation does not consider loans and leases for impairment unless a sustained period of delinquency (i.e., 90-plus days) is noted or there are subsequent events that impact repayment probability (i.e., negative financial trends, bankruptcy filings, imminent foreclosure proceedings, etc.). Impairment is evaluated in the aggregate for consumer installment loans, residential mortgages, consumer lines of credit and commercial loan and lease relationships less than $500 based on loan and lease segment loss given default. For commercial loan relationships greater than or equal to $500, a specific valuation allowance is allocated, if necessary, so that the loan is reported net, at the present value of estimated future cash flows using a market interest rate or at the fair value of collateral if repayment is expected solely from the collateral. Consistent with the Corporation’s existing method of income recognition for loans and leases, interest on impaired loans, except those classified as non-accrual, is recognized as income using the accrual method. Impaired loans, or portions thereof, are charged off when deemed uncollectible.
Following is a summary of information pertaining to originated loans and leases considered to be impaired, by class of loan and lease:
		Unpaid			Recorded			Recorded		Total		Specific			Average
		Contractual			Investment			Investment		Recorded		Reserve			Recorded
		Principal			With No			With		Investment					Investment
		Balance			Specific			Specific
					Reserve			Reserve
At or for the Three Months Ended March 31, 2015
Commercial real estate		$	34,483		$	25,015		$	1,012	$	26,027	$	735		$	26,176
Commercial and industrial			11,251			8,138			1,928		10,066		1,446			9,811
Commercial leases			732			732			—		732		—			727
Total commercial loans and leases			46,466			33,885			2,940		36,825		2,181			36,714
Direct installment			13,977			13,768			—		13,768		—			14,343
Residential mortgages			15,718			14,472			—		14,472		—			15,547
Indirect installment			1,425			1,265			—		1,265		—			1,363
Consumer lines of credit			1,600			1,589			—		1,589		—			1,696
Other			—			—			—		—		—			—
		$	79,186		$	64,979		$	2,940	$	67,919	$	2,181		$	69,663
At or for the Year Ended December 31, 2014
Commercial real estate		$	34,583		$	25,443		$	883	$	26,326	$	399		$	30,807
Commercial and industrial			11,412			7,609			1,948		9,557		780			9,510
Commercial leases			722			722			—		722		—			686
Total commercial loans and leases			46,717			33,774			2,831		36,605		1,179			41,003
Direct installment			14,987			14,680			—		14,680		—			14,248
Residential mortgages			16,791			15,064			—		15,064		—			16,924
Indirect installment			1,467			1,305			—		1,305		—			1,399
Consumer lines of credit			1,803			1,796			—		1,796		—			1,793
Other			—			—			—		—		—			—
		$	81,765		$	66,619		$	2,831	$	69,450	$	1,179		$	75,367
Interest income is generally no longer recognized once a loan becomes impaired.
These tables do not reflect the additional allowance for credit losses relating to acquired loans in the following pools and categories: commercial real estate of $3,327; commercial and industrial of $712; direct installment of $1,477; residential mortgages of $1,193; indirect installment of $229; and consumer lines of credit of $314, totaling $7,252 at March 31, 2015 and commercial real estate of $3,286; commercial and industrial of $1,484; direct installment of $1,847; residential mortgages of $858; indirect installment of $232; and consumer lines of credit of $267, totaling $7,974 at December 31, 2014.
Troubled Debt Restructurings
TDRs are loans whose contractual terms have been modified in a manner that grants a concession to a borrower experiencing financial difficulties. TDRs typically result from loss mitigation activities and could include the extension of a maturity date, interest rate reduction, principal forgiveness, deferral or decrease in payments for a period of time and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of collateral.
Following is a summary of the payment status of total TDRs:
		March 31,			December 31,
		2015			2014
Accruing:
Performing		$	12,793		$	9,441
Non-performing			22,022			23,439
Non-accrual			8,040			8,272
		$	42,855		$	41,152
TDRs that are accruing and performing include loans that met the criteria for non-accrual of interest prior to restructuring for which the Corporation can reasonably estimate the timing and amount of the expected cash flows on such loans and for which the Corporation expects to fully collect the new carrying value of the loans. During the three months ended March 31, 2015, the Corporation returned to performing status $3,975 in restructured residential mortgage loans that have consistently met their modified obligations for more than six months. TDRs that are accruing and non-performing are comprised of consumer loans that have not demonstrated a consistent repayment pattern on the modified terms for more than six months, however it is expected that the Corporation will collect all future principal and interest payments. TDRs that are on non-accrual are not placed on accruing status until all delinquent principal and interest have been paid and the ultimate collectability of the remaining principal and interest is reasonably assured. Some loan modifications classified as TDRs may not ultimately result in the full collection of principal and interest, as modified, and may result in potential incremental losses which are factored into the allowance for credit losses.
Excluding purchased impaired loans, commercial loans over $500 whose terms have been modified in a TDR are generally placed on non-accrual, individually analyzed and measured for estimated impairment based on the fair value of the underlying collateral. The Corporation’s allowance for credit losses included specific reserves for commercial TDRs of $646 and $371 at March 31, 2015 and December 31, 2014, respectively, and pooled reserves for individual loans under $500 of $1,203 and $1,215 for those same respective periods, based on loan segment loss given default. Upon default, the amount of the recorded investment in the TDR in excess of the fair value of the collateral, less estimated selling costs, is generally considered a confirmed loss and is charged-off against the allowance for credit losses.
All other classes of loans, which are primarily secured by residential properties, whose terms have been modified in a TDR are pooled and measured for estimated impairment based on the expected net present value of the estimated future cash flows of the pool. The Corporation’s allowance for credit losses included pooled reserves for these classes of loans of $4,146 and $3,448 at March 31, 2015 and December 31, 2014, respectively. Upon default of an individual loan, the Corporation’s charge-off policy is followed accordingly for that class of loan.
The majority of TDRs are the result of interest rate concessions for a limited period of time. Following is a summary of loans, by class, that have been restructured:
		Three Months Ended March 31, 2015								Three Months Ended March 31, 2014
		Number			Pre-Modification			Post-		Number		Pre-Modification			Post-
		of			Outstanding			Modification		of		Outstanding			Modification
		Contracts			Recorded			Outstanding		Contracts		Recorded			Outstanding
					Investment			Recorded				Investment			Recorded
								Investment							Investment
Commercial real estate			2		$	312		$	196		1	$	188		$	188
Commercial and industrial			—			—			—		1		52			50
Total commercial loans			2			312			196		2		240			238
Direct installment			131			1,526			1,484		126		1,678			1,647
Residential mortgages			14			581			631		9		281			280
Indirect installment			5			16			16		7		17			16
Consumer lines of credit			16			270			270		7		255			255
Other			—			—			—		—		—			—
			168		$	2,705		$	2,597		151	$	2,471		$	2,436
Following is a summary of TDRs, by class of loans and leases, for which there was a payment default, excluding loans that were either charged-off or cured by period end. Default occurs when a loan is 90 days or more past due and is within 12 months of restructuring.
		Three Months Ended						Three Months Ended
		March 31, 2015 (1)						March 31, 2014 (1)
		Number of			Recorded			Number of		Recorded
		Contracts			Investment			Contracts		Investment
Direct installment			37		$	105			18	$	171
Residential mortgages			2			102			—		—
Indirect installment			3			4			1		—
Consumer lines of credit			1			92			—		—
Other			—			—			—		—
			43		$	303			19	$	171
-1	The recorded investment is as of period end.

Allowance_for_Credit_Losses

Allowance for Credit Losses	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Allowance for Credit Losses	ALLOWANCE FOR CREDIT LOSSES
	The allowance for credit losses is established as losses are estimated to have occurred through a provision charged to earnings. Losses are charged against the allowance for credit losses when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance for credit losses. Allowances for impaired commercial loans over $500 are generally determined based on collateral values or the present value of estimated cash flows. All other impaired loans and leases are evaluated in the aggregate based on loan segment loss given default. Changes in the allowance for credit losses related to impaired loans and leases are charged or credited to the provision for credit losses.
	The allowance for credit losses is maintained at a level that, in management’s judgment, is believed adequate to absorb probable losses associated with specifically identified loans and leases, as well as estimated probable credit losses inherent in the remainder of the portfolio. Adequacy of the allowance for credit losses is based on management’s evaluation of potential losses in the portfolio, which includes an assessment of past experience, current economic conditions in specific industries and geographic areas, general economic conditions, known and inherent risks in the portfolio, the estimated value of underlying collateral and residuals and changes in the composition of the portfolio. Determination of the allowance for credit losses is inherently subjective as it requires significant estimates, including the amounts and timing of expected future cash flows on impaired loans and leases, estimated losses on pools of homogeneous loans and leases based on transition matrices with predefined loss emergence periods and consideration of qualitative factors, all of which are susceptible to significant change.
	Credit impaired loans obtained through acquisitions are accounted for under the provisions of ASC 310-30. The Corporation also accounts for certain acquired loans considered performing at the time of acquisition by analogy to ASC 310-30. ASC 310-30 requires the initial recognition of acquired loans at the present value of amounts expected to be received. Any deterioration in the credit quality of acquired loans subsequent to acquisition would be considered in the allowance for credit losses.
	Following is a summary of changes in the allowance for credit losses, by loan and lease class:
		Balance at		Charge-			Recoveries		Net			Provision			Balance at
		Beginning		Offs					Charge-			for credit			End of
		of Period							Offs			losses			Period
	Three Months Ended March 31, 2015
	Commercial real estate	$	37,588	$	(1,001	)	$	209	$	(792	)	$	1,996		$	38,792
	Commercial and industrial		32,645		(684	)		120		(564	)		722			32,803
	Commercial leases		2,398		(93	)		10		(83	)		261			2,576
	Total commercial loans and leases		72,631		(1,778	)		339		(1,439	)		2,979			74,171
	Direct installment		20,538		(2,433	)		269		(2,164	)		2,830			21,204
	Residential mortgages		8,024		(511	)		15		(496	)		943			8,471
	Indirect installment		7,504		(1,280	)		302		(978	)		1,131			7,657
	Consumer lines of credit		8,496		(410	)		40		(370	)		764			8,890
	Other		759		(335	)		11		(324	)		419			854
	Total allowance on originated loans and leases		117,952		(6,747	)		976		(5,771	)		9,066			121,247
	Purchased credit-impaired loans		660		(64	)		19		(45	)		6			621
	Other acquired loans		7,314		(77	)		330		253			(936	)		6,631
	Total allowance on acquired loans		7,974		(141	)		349		208			(930	)		7,252
	Total allowance	$	125,926	$	(6,888	)	$	1,325	$	(5,563	)	$	8,136		$	128,499
	Three Months Ended March 31, 2014
	Commercial real estate	$	32,548	$	(2,223	)	$	299	$	(1,924	)	$	7,910		$	38,534
	Commercial and industrial		32,603		(513	)		370		(143	)		(2,489	)		29,971
	Commercial leases		1,903		(87	)		29		(58	)		99			1,944
	Total commercial loans and leases		67,054		(2,823	)		698		(2,125	)		5,520			70,449
	Direct installment		17,824		(2,521	)		267		(2,254	)		1,060			16,630
	Residential mortgages		5,836		(132	)		4		(128	)		(401	)		5,307
	Indirect installment		6,409		(802	)		217		(585	)		676			6,500
	Consumer lines of credit		7,231		(323	)		55		(268	)		695			7,658
	Other		530		(262	)		5		(257	)		306			579
	Total allowance on originated loans and leases		104,884		(6,863	)		1,246		(5,617	)		7,856			107,123
	Purchased credit-impaired loans		1,000		(249	)		—		(249	)		(43	)		708
	Other acquired loans		4,900		9			286		295			(807	)		4,388
	Total allowance on acquired loans		5,900		(240	)		286		46			(850	)		5,096
	Total allowance	$	110,784	$	(7,103	)	$	1,532	$	(5,571	)	$	7,006		$	112,219
	Following is a summary of the individual and collective originated allowance for credit losses and corresponding loan and lease balances by class:
		Allowance					Loans and Leases Outstanding
		Individually		Collectively			Loans and		Individually			Collectively
		Evaluated for		Evaluated for			Leases		Evaluated for			Evaluated for
		Impairment		Impairment					Impairment			Impairment
	March 31, 2015
	Commercial real estate	$	735	$	38,057		$	3,082,385	$	12,865		$	3,069,520
	Commercial and industrial		1,446		31,357			2,281,075		5,711			2,275,364
	Commercial leases		—		2,576			180,207		—			180,207
	Total commercial loans and leases		2,181		71,990			5,543,667		18,576			5,525,091
	Direct installment		—		21,204			1,594,846		—			1,594,846
	Residential mortgages		—		8,471			877,437		—			877,437
	Indirect installment		—		7,657			903,780		—			903,780
	Consumer lines of credit		—		8,890			953,569		—			953,569
	Other		—		854			42,632		—			42,632
		$	2,181	$	119,066		$	9,915,931	$	18,576		$	9,897,355
	December 31, 2014
	Commercial real estate	$	399	$	37,189		$	3,031,810	$	13,952		$	3,017,858
	Commercial and industrial		780		31,865			2,197,793		5,837			2,191,956
	Commercial leases		—		2,398			177,824		—			177,824
	Total commercial loans and leases		1,179		71,452			5,407,427		19,789			5,387,638
	Direct installment		—		20,538			1,579,770		—			1,579,770
	Residential mortgages		—		8,024			817,586		—			817,586
	Indirect installment		—		7,504			873,645		—			873,645
	Consumer lines of credit		—		8,496			946,427		—			946,427
	Other		—		759			41,290		—			41,290
	$	1,179	$	116,773		$	9,666,145	$	19,789		$	9,646,356

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Borrowings	BORROWINGS
	Following is a summary of short-term borrowings:
		March 31,		December 31,
		2015		2014
	Securities sold under repurchase agreements	$	757,279	$	882,696
	Federal Home Loan Bank advances		500,000		820,000
	Federal funds purchased		355,000		210,000
	Subordinated notes		128,221		128,962
		$	1,740,500	$	2,041,658
	Securities sold under repurchase agreements is comprised of customer repurchase agreements, which are sweep accounts with next day maturities utilized by larger commercial customers to earn interest on their funds. Securities are pledged to these customers in an amount equal to the outstanding balance.
	Following is a summary of long-term borrowings:
		March 31,		December 31,
		2015		2014
	Federal Home Loan Bank advances	$	400,018	$	400,042
	Subordinated notes		83,197		83,155
	Junior subordinated debt		58,259		58,246
		$	541,474	$	541,443
	The Corporation’s banking affiliate has available credit with the FHLB of $4,213,966 of which $900,018 was used as of March 31, 2015. These advances are secured by loans collateralized by residential mortgages, HELOCs, commercial real estate and FHLB stock and are scheduled to mature in various amounts periodically through the year 2021. Effective interest rates paid on the long-term advances ranged from 0.76% to 4.19% for both the three months ended March 31, 2015 and the year ended December 31, 2014.
	The Corporation had two unconsolidated subsidiary trusts as of March 31, 2015 (collectively, the Trusts): F.N.B. Statutory Trust II and Omega Financial Capital Trust I. One hundred percent of the common equity of each Trust is owned by the Corporation. The Trusts were formed for the purpose of issuing Corporation-obligated mandatorily redeemable capital securities (TPS) to third-party investors. The proceeds from the sale of TPS and the issuance of common equity by the Trusts were invested in junior subordinated debt securities (subordinated debt) issued by the Corporation, which are the sole assets of each Trust. Since third-party investors are the primary beneficiaries, the Trusts are not consolidated in the Corporation’s financial statements. The Trusts pay dividends on the TPS at the same rate as the distributions paid by the Corporation on the junior subordinated debt held by the Trusts. Omega Financial Capital Trust I was assumed as a result of an acquisition.
	Distributions on the subordinated debt issued to the Trusts are recorded as interest expense by the Corporation. The TPS are subject to mandatory redemption, in whole or in part, upon repayment of the subordinated debt. The TPS are eligible for redemption, at any time, at the Corporation’s discretion. Under recently issued capital guidelines, effective January 1, 2015, the portion of the subordinated debt, net of the Corporation’s investments in the Trusts, that qualifies as tier 1 capital is limited to 25% of the total $57,500 outstanding at March 31, 2015, with the remaining 75% moving to tier 2 capital. In 2016, the entire balance of the subordinated debt will be included in tier 2 capital. The Corporation has entered into agreements which, when taken collectively, fully and unconditionally guarantee the obligations under the TPS subject to the terms of each of the guarantees.
	The following table provides information relating to the Trusts as of March 31, 2015:
		Trust		Common		Junior		Stated		Interest
		Preferred		Securities		Subordinated		Maturity		Rate
		Securities				Debt		Date
	F.N.B. Statutory Trust II	$	21,500	$	665	$	22,165		6/15/36		1.92	%	Variable; LIBOR + 165 basis points (bps)
	Omega Financial Capital Trust I		36,000		1,114		36,094		10/18/34		2.44	%	Variable; LIBOR + 219 bps
		$	57,500	$	1,779	$	58,259

Derivative_And_Hedging_Activit

Derivative And Hedging Activities	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative And Hedging Activities	DERIVATIVE AND HEDGING ACTIVITIES
	The Corporation is exposed to certain risks arising from both its business operations and economic conditions. The Corporation principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Corporation manages economic risks, including interest rate risk, primarily by managing the amount, source, and duration of its assets and liabilities, and through the use of derivative instruments. Derivative instruments are used to reduce the effects that changes in interest rates may have on net income and cash flows. The Corporation also uses derivative instruments to facilitate transactions on behalf of its customers.
	All derivatives are carried on the consolidated balance sheet at fair value and do not take into account the effects of master netting arrangements the Corporation has with other financial institutions. Credit risk is included in the determination of the estimated fair value of derivatives. Derivative assets are classified in the consolidated balance sheet under other assets and derivative liabilities are classified in the consolidated balance sheet under other liabilities. Changes in fair value are recognized in earnings except for certain changes related to derivative instruments designated as part of a cash flow hedging relationship.
	The following table presents notional amounts and gross fair values of all derivative assets and derivative liabilities held by the Corporation:
		March 31, 2015								December 31, 2014
		Notional		Fair Value						Notional		Fair Value
		Amount		Asset			Liability			Amount		Asset		Liability
	Gross Derivatives
	Subject to master netting arrangements:
	Interest rate contracts – designated	$	200,000	$	3,937		$	669		$	200,000	$	2,109	$	2,330
	Interest rate swaps – not designated		1,020,957		6			53,718			972,002		140		43,655
	Equity contracts – not designated		1,210		39			—			1,210		47		—
	Total subject to master netting arrangements		1,222,167		3,982			54,387			1,173,212		2,296		45,985
	Not subject to master netting arrangements:
	Interest rate swaps – not designated		1,020,957		53,569			5			972,002		43,602		128
	Credit risk contracts – not designated		76,416		—			—			68,632		—		—
	Equity contracts – not designated		1,210		—			39			1,210		—		47
	Total not subject to master netting arrangements		1,098,583		53,569			44			1,041,844		43,602		175
		$	2,320,750	$	57,551		$	54,431		$	2,215,056	$	45,898	$	46,160
	Derivatives Designated as Hedging Instruments under GAAP
	Interest Rate Contracts. The Corporation entered into interest rate derivative agreements to modify the interest rate characteristics of designated commercial loans from variable rate to fixed rate in order to reduce the impact of changes in future cash flows due to market interest rate changes. These agreements are designated as cash flow hedges (i.e., hedging the exposure to variability in expected future cash flows). The effective portion of the derivative’s gain or loss is initially reported as a component of other comprehensive income and subsequently reclassified into earnings in the same line item associated with the forecasted transaction when the forecasted transaction affects earnings. The ineffective portion of the gain or loss is reported in earnings immediately.
	At March 31, 2015 and December 31, 2014, the notional amount of these interest rate derivative agreements totaled $200,000. Fair values included in other assets and other liabilities on the consolidated balance sheet applicable to these agreements amounted to $3,937 and $669, respectively, at March 31, 2015, and $2,109 and $2,330, respectively, at December 31, 2014. For the three months ended March 31, 2015, the amount reclassified from accumulated other comprehensive income (AOCI) to interest income on loans and leases totaled $810 ($526 net of tax).
	As of March 31, 2015, the maximum length of time over which forecasted interest cash flows are hedged is nine years. In the twelve months that follow March 31, 2015, the Corporation expects to reclassify from the amount currently reported in AOCI net derivative gains of $2,929 ($1,904 net of tax), in association with interest received on the hedged loans. This amount could differ from amounts actually recognized due to changes in interest rates, hedge de-designations, and the addition of other hedges subsequent to March 31, 2015.
	There were no components of derivative gains or losses excluded from the assessment of hedge effectiveness related to these cash flow hedges. For the three months ended March 31, 2015 and 2014, there was no hedge ineffectiveness. Also, during the three months ended March 31, 2015 and 2014, there were no gains or losses from cash flow hedge derivatives reclassified to earnings because it became probable that the original forecasted transactions would not occur.
	Derivatives Not Designated as Hedging Instruments under GAAP
	Interest Rate Swaps. The Corporation enters into interest rate swap agreements to meet the financing, interest rate and equity risk management needs of qualifying commercial loan customers. These agreements provide the customer the ability to convert from variable to fixed interest rates. The credit risk associated with derivatives executed with customers is essentially the same as that involved in extending loans and is subject to normal credit policies and monitoring. Swap derivative transactions with customers are not subject to enforceable master netting arrangements and are generally secured by rights to non-financial collateral, such as real and personal property.
	The Corporation enters into positions with a derivative counterparty in order to offset its exposure on the fixed components of the customer interest rate swap agreements. The Corporation seeks to minimize counterparty credit risk by entering into transactions with only high-quality financial dealer institutions. These arrangements meet the definition of derivatives, but are not designated as hedging instruments under ASC 815, Derivatives and Hedging. Substantially all contracts with dealers that require central clearing (generally, transactions since June 10, 2014) are novated to a SEC registered clearing agency who becomes the Corporation’s counterparty.
	The notional amount of these customer derivative agreements and the offsetting derivative counterparty positions each totaled $1,020,957 at March 31, 2015. Fair values included in other assets and other liabilities on the consolidated balance sheet applicable to these agreements amounted to $53,575 and $53,723, respectively, at March 31, 2015. At December 31, 2014, the notional amount of these customer derivative agreements and the offsetting derivative counterparty positions each totaled $972,002. At December 31, 2014, fair values included in other assets and other liabilities on the consolidated balance sheet amounted to $43,742 and $43,783, respectively.
	The interest rate swap agreement with the loan customer and with the counterparty is reported at fair value in other assets and other liabilities on the consolidated balance sheet with any resulting gain or loss recorded in current period earnings as other income or other expense.
	Credit Risk Contracts. The Corporation purchases and sells credit protection under risk participation agreements to share with other counterparties some of the credit exposure related to interest rate derivative contracts or to take on credit exposure to generate revenue. The Corporation will make/receive payments under these agreements if a customer defaults on its obligation to perform under certain derivative swap contracts.
	Risk participation agreements sold with notional amounts totaling $50,061 have remaining terms ranging from two to nine years. Under these agreements, the Corporation’s maximum exposure assuming a customer defaults on its obligation to perform under certain derivative swap contracts with third parties would be $70 at March 31, 2015 and $21 at December 31, 2014.
	The fair values of risk participation agreements purchased and sold were not material at March 31, 2015 and December 31, 2014.
	Counterparty Credit Risk
	The Corporation is party to master netting arrangements with most of its swap derivative counterparties. Collateral, usually marketable securities and/or cash, is exchanged between the Corporation and its counterparties, and is generally subject to thresholds and transfer minimums. For swap transactions that require central clearing, the Corporation posts cash to its clearing agency. Collateral positions are valued daily, and adjustments to amounts received and pledged by the Corporation are made as appropriate to maintain proper collateralization for these transactions.
	Certain master netting agreements contain provisions that, if violated, could cause the counterparties to request immediate settlement or demand full collateralization under the derivative instrument. If the Corporation had breached its agreements with its derivative counterparties it would be required to settle its obligations under the agreements at the termination value and would be required to pay an additional $2,071 and $1,862 as of March 31, 2015 and December 31, 2014, respectively, in excess of amounts previously posted as collateral with the respective counterparty.
	The following table presents information about derivative assets and derivative liabilities that are subject to enforceable master netting arrangements as well as those not subject to enforceable master netting arrangements:
		Gross		Gross			Net Amount
		Amount		Amounts			Presented in
				Offset in			the Balance
				the Balance			Sheet
				Sheet
	March 31, 2015
	Derivative Assets
	Subject to master netting arrangements:
	Interest rate contracts
	Designated	$	3,937		—		$	3,937
	Not designated		6		—			6
	Equity contracts – not designated		39		—			39
	Not subject to master netting arrangements:
	Interest rate contracts – not designated		53,569		—			53,569
		$	57,551		—		$	57,551
	Derivative Liabilities
	Subject to master netting arrangements:
	Interest rate contracts
	Designated	$	669		—		$	669
	Not designated		53,718		—			53,718
	Not subject to master netting arrangements:
	Interest rate contracts – not designated		5		—			5
	Equity contracts – not designated		39		—			39
		$	54,431		—		$	54,431
	December 31, 2014
	Derivative Assets
	Subject to master netting arrangements:
	Interest rate contracts
Designated	$	2,109		—		$	2,109
Not designated		140		—			140
Equity contracts – not designated		47		—			47
Not subject to master netting arrangements:
Interest rate contracts – not designated		43,602		—			43,602
	$	45,898		—		$	45,898
Derivative Liabilities
Subject to master netting arrangements:
Interest rate contracts
Designated	$	2,330		—		$	2,330
Not designated		43,655		—			43,655
Not subject to master netting arrangements:
Interest rate contracts – not designated		128		—			128
Equity contracts – not designated		47		—			47
	$	46,160		—		$	46,160
The following table presents a reconciliation of the net amounts of derivative assets and derivative liabilities presented in the balance sheet to the net amounts that would result in the event of offset:
	Net Amount		Amount Not Offset in the
	Presented in		Balance Sheet
	the Balance		Financial			Cash			Net
	Sheet		Instruments			Collateral			Amount
March 31, 2015
Derivative Assets
Interest rate contracts:
Designated	$	3,937	$	1,902		$	2,035			—
Not designated		6		6			—			—
Equity contracts – not designated		39		39			—			—
	$	3,982	$	1,947		$	2,035			—
Derivative Liabilities
Interest rate contracts:
Designated	$	669	$	669		$	—		$	—
Not designated		53,718		30,626			21,346			1,746
	$	54,387	$	31,295		$	21,346		$	1,746
December 31, 2014
Derivative Assets
Interest rate contracts:
Designated	$	2,109	$	810		$	1,299			—
Not designated		140		138			2			—
Equity contracts – not designated		47		47			—			—
	$	2,296	$	995		$	1,301			—
Derivative Liabilities
Interest rate contracts:
Designated	$	2,330	$	2,330		$	—		$	—
Not designated		43,655		28,646			13,243			1,766
	$	45,985	$	30,976		$	13,243		$	1,766
The following table presents the effect of the Corporation’s derivative financial instruments on the income statement:
	Income		Three Months Ended
	Statement		March 31,
	Location		2015			2014
Interest Rate Products		Other income	$	(107	)	$	(14	)
Other
The Corporation has entered into interest rate lock commitments to originate residential mortgage loans held for sale and forward commitments to sell residential mortgage loans to secondary market investors. These arrangements are considered derivative instruments. The fair values of the Corporation’s rate lock commitments to customers and commitments with investors at March 31, 2015 and December 31, 2014 are not material.

Commitments_Credit_Risk_and_Co

Commitments, Credit Risk and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments, Credit Risk and Contingencies	COMMITMENTS, CREDIT RISK AND CONTINGENCIES
	The Corporation has commitments to extend credit and standby letters of credit that involve certain elements of credit risk in excess of the amount stated in the consolidated balance sheet. The Corporation’s exposure to credit loss in the event of non-performance by the customer is represented by the contractual amount of those instruments. The credit risk associated with loan commitments and standby letters of credit is essentially the same as that involved in extending loans and leases to customers and is subject to normal credit policies. Since many of these commitments expire without being drawn upon, the total commitment amounts do not necessarily represent future cash flow requirements.
	Following is a summary of off-balance sheet credit risk information:
		March 31,		December 31,
		2015		2014
	Commitments to extend credit	$	3,969,614	$	3,665,481
	Standby letters of credit		109,355		121,186
	At March 31, 2015, funding of 68.2% of the commitments to extend credit was dependent on the financial condition of the customer. The Corporation has the ability to withdraw such commitments at its discretion. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Based on management’s credit evaluation of the customer, collateral may be deemed necessary. Collateral requirements vary and may include accounts receivable, inventory, property, plant and equipment and income-producing commercial properties.
	Standby letters of credit are conditional commitments issued by the Corporation that may require payment at a future date. The credit risk involved in issuing letters of credit is quantified on a quarterly basis, through the review of historical performance of the Corporation’s portfolios and allocated as a liability on the Corporation’s balance sheet.
	Other Legal Proceedings
	The Corporation and its subsidiaries are involved in various pending legal proceedings in which claims for monetary damages and other relief are asserted. These actions include claims brought against the Corporation and its subsidiaries where the Corporation or a subsidiary acted as one or more of the following: a depository bank, lender, underwriter, fiduciary, financial advisor, broker, agent, acquiror or was engaged in other business activities. Although the ultimate outcome for any asserted claim cannot be predicted with certainty, the Corporation believes that it and its subsidiaries have valid defenses for all asserted claims. Reserves are established for legal claims when losses associated with the claims are judged to be probable and the amount of the loss can be reasonably estimated.
	Based on information currently available, advice of counsel, available insurance coverage and established reserves, the Corporation does not anticipate, at the present time, that the aggregate liability, if any, arising out of such legal proceedings will have a material adverse effect on the Corporation’s consolidated financial position. However, the Corporation cannot determine whether or not any claims asserted against it will have a material adverse effect on its consolidated results of operations in any future reporting period.

Stock_Incentive_Plans

Stock Incentive Plans	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Incentive Plans	STOCK INCENTIVE PLANS
	Restricted Stock
	The Corporation issues restricted stock awards, consisting of both restricted stock and restricted stock units, to key employees under its Incentive Compensation Plans (Plans). The Corporation issues time-based awards and performance-based awards under these Plans, both of which are based on a three-year vesting period. The grant date fair value of the time-based awards is equal to the price of the Corporation’s common stock on the grant date. The fair value of the performance-based awards is based on a Monte-Carlo Simulation valuation of the Corporation’s common stock as of the grant date.
	The Corporation did not issue any restricted stock awards during the three months ended March 31, 2015 or 2014. For performance-based restricted stock awards granted since 2014, the amount of shares recipients will earn is variable based on the Corporation’s total stockholder return relative to a specified peer group of financial institutions over the three-year period. These market-based restricted stock units are included in the table below as if the recipients earned shares equal to 100% of the units issued. As of March 31, 2015, the Corporation had available up to 2,122,522 shares of common stock to issue under the Plans.
	The unvested restricted stock awards are eligible to receive cash dividends or dividend equivalents which are ultimately used to purchase additional shares of stock and are subject to forfeiture if the requisite service period is not completed or the specified performance criteria are not met. These awards are subject to certain accelerated vesting provisions upon retirement, death, disability or in the event of a change of control as defined in the award agreements.
	Share-based compensation expense related to restricted stock awards was $340 and $532 for the three months ended March 31, 2015 and 2014, the tax benefit of which was $119 and $186, respectively.
	The following table summarizes certain information concerning restricted stock awards:
		Three Months Ended March 31,
		2015					2014
		Awards			Weighted		Awards			Weighted
					Average					Average
					Grant					Grant
					Price					Price
	Unvested awards outstanding at beginning of period		1,354,093		$	11.86		1,729,033		$	10.23
	Net adjustment due to performance		(46,956	)		10.25		(19,002	)		8.48
	Vested		(458,450	)		10.6		(667,956	)		9.01
	Forfeited		(2,357	)		17.93		(430	)		10.69
	Dividend reinvestment		7,656			14.24		9,612			13.01
	Unvested awards outstanding at end of period		853,986			12.63		1,051,257			11.06
	The total fair value of awards vested was $5,740 and $8,631 for the three months ended March 31, 2015 and 2014, respectively.
	As of March 31, 2015, there was $4,509 of unrecognized compensation cost related to unvested restricted stock awards, including $20 that is subject to accelerated vesting under the Plan’s immediate vesting upon retirement provision for awards granted prior to the adoption of ASC 718, Compensation – Stock Compensation. The components of the restricted stock awards as of March 31, 2015 are as follows:
		Service-			Performance-		Total
		Based			Based
		Awards			Awards
	Unvested awards		397,593			456,393		853,986
	Unrecognized compensation expense	$	2,659		$	1,850	$	4,509
	Intrinsic value	$	5,224		$	5,997	$	11,221
	Weighted average remaining life (in years)		1.91			1.73		1.81
	Stock Options
	All outstanding stock options were assumed from acquisitions and are fully vested. Upon consummation of the Corporation’s acquisitions, all outstanding stock options issued by the acquired companies were converted into equivalent Corporation stock options. The Corporation issues shares of treasury stock or authorized but unissued shares to satisfy stock options exercised. Shares issued upon the exercise of stock options were 60,094 and 59,217 for the three months ended March 31, 2015 and 2014, respectively.
	The following table summarizes certain information concerning stock option awards:
		Three Months Ended March 31,
		2015					2014
		Shares			Weighted		Shares			Weighted
					Average					Average
					Exercise					Exercise
					Price					Price
	Options outstanding at beginning of period		568,834		$	8.86		533,524		$	11.5
	Assumed from acquisition		—			—		304,785			5.77
	Exercised		(60,094	)		5.04		(87,332	)		6.05
	Forfeited		(2,182	)		4.34		(48,172	)		25.79
	Options outstanding and exercisable at end of period		506,558			9.33		702,805			8.71
	The intrinsic value of outstanding and exercisable stock options at March 31, 2015 was $1,890.
	Warrants
	In conjunction with its participation in the U.S. Department of the Treasury’s (UST) Capital Purchase Program (CPP), the Corporation issued to the UST a warrant to purchase up to 1,302,083 shares of the Corporation’s common stock. Pursuant to Section 13(H) of the Warrant to Purchase Common Stock, the number of shares of common stock issuable upon exercise of the warrant was reduced in half to 651,042 shares on June 16, 2009, the date the Corporation completed a public offering. The warrant, which expires in 2019, has an exercise price of $11.52 per share.
	In conjunction with the Parkvale Financial Corporation (Parkvale) acquisition on January 1, 2012, the warrant issued by Parkvale to the UST under the CPP has been converted into a warrant to purchase up to 819,640 shares of the Corporation’s common stock. This warrant, which was recorded at its fair value on January 1, 2012, expires in 2018 and has an exercise price of $5.81 per share.
	In conjunction with the Annapolis Bancorp, Inc. (ANNB) acquisition on April 6, 2013, the warrant issued by ANNB to the UST under the CPP has been converted into a warrant to purchase up to 342,564 shares of the Corporation’s common stock at an exercise price of $3.57 per share. Subsequent adjustments related to actual dividends paid by the Corporation have increased the share amount of these warrants to 367,916, with a resulting lower exercise price of $3.32 per share as of March 31, 2015. The warrant, which was recorded at its fair value on April 6, 2013, expires in 2019.

Retirement_Plans

Retirement Plans	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Retirement Plans	RETIREMENT PLANS
	The Corporation sponsors the Retirement Income Plan (RIP), a qualified noncontributory defined benefit pension plan that covered substantially all salaried employees hired prior to January 1, 2008. The RIP covers employees who satisfied minimum age and length of service requirements. The Corporation’s funding guideline has been to make annual contributions to the RIP each year, if necessary, such that minimum funding requirements have been met. The RIP was frozen as of December 31, 2010.
	The Corporation also sponsors two supplemental non-qualified retirement plans. The ERISA Excess Retirement Plan provides retirement benefits equal to the difference, if any, between the maximum benefit allowable under the Internal Revenue Code and the amount that would be provided under the RIP, if no limits were applied. The Basic Retirement Plan (BRP) is applicable to certain officers whom the Board of Directors designates. Officers participating in the BRP receive a benefit based on a target benefit percentage based on years of service at retirement and a designated tier as determined by the Board of Directors. When a participant retires, the basic benefit under the BRP is a monthly benefit equal to the target benefit percentage times the participant’s highest average monthly cash compensation during five consecutive calendar years within the last ten calendar years of employment. This monthly benefit is reduced by the monthly benefit the participant receives from Social Security, the RIP, the ERISA Excess Retirement Plan and the annuity equivalent of the three percent automatic contributions to the qualified 401(k) defined contribution plan and the ERISA Excess Lost Match Plan. The BRP was frozen as of December 31, 2008. The ERISA Excess Retirement Plan was frozen as of December 31, 2010.
	The net periodic benefit credit for the defined benefit plans includes the following components:
		Three Months Ended
		March 31,
		2015			2014
	Service cost	$	17		$	16
	Interest cost		1,477			1,596
	Expected return on plan assets		(2,491	)		(2,487	)
	Amortization:
	Unrecognized net transition asset		—			(5	)
	Unrecognized prior service cost		2			2
	Unrecognized loss		536			337
	Net periodic pension credit	$	(459	)	$	(541	)
	The Corporation’s subsidiaries participate in a qualified 401(k) defined contribution plan under which employees may contribute a percentage of their salary. Employees are eligible to participate upon their first day of employment. Under this plan, the Corporation matches 100% of the first six percent that the employee defers. Additionally, the Corporation may provide a performance-based company contribution of up to three percent if the Corporation exceeds annual financial goals. Prior to January 1, 2015, the Corporation matched 100% of the first four percent that the employee deferred, provided an automatic contribution of three percent of compensation at the end of the year and could make an additional performance-based company contribution of up to two percent if the Corporation achieved its performance goals for the plan year. The Corporation’s contribution expense was $2,167 and $2,570 for the three months ended March 31, 2015 and 2014, respectively.
	The Corporation also sponsors an ERISA Excess Lost Match Plan for certain officers. This plan provides retirement benefits equal to the difference, if any, between the maximum benefit allowable under the Internal Revenue Code and the amount that would have been provided under the qualified 401(k) defined contribution plan, if no limits were applied.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES
	The Corporation bases its provision for income taxes upon income before income taxes, adjusted for the effect of certain tax-exempt income and non-deductible expenses. In addition, the Corporation reports certain items of income and expense in different periods for financial reporting and tax return purposes. The Corporation recognizes the tax effects of these temporary differences currently in the deferred income tax provision or benefit. The Corporation computes deferred tax assets or liabilities based upon the differences between the financial statement and income tax bases of assets and liabilities using the applicable marginal tax rate.
	The Corporation evaluates the probability that it will ultimately realize the full value of its deferred tax assets. Realization of the Corporation’s deferred tax assets is dependent upon a number of factors including the existence of any cumulative losses in prior periods, the amount of taxes paid in available carry-back periods, expectations for future earnings, applicable tax planning strategies and assessment of current and future economic and business conditions. The Corporation establishes a valuation allowance when it is “more likely than not” that the Corporation will not be able to realize a benefit from its deferred tax assets, or when future deductibility is uncertain.
	At March 31, 2015, the Corporation anticipates that it will not utilize some of its state net operating loss carryforwards and other net deferred tax assets at certain of its subsidiaries and has recorded a valuation allowance against these deferred tax assets. The Corporation believes that, except for the portion which is covered by a valuation allowance, it is more likely than not the Corporation will realize the benefits of its deferred tax assets, net of the valuation allowance, at March 31, 2015, based on the levels of projected taxable income of some of its entities.

Comprehensive_Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Comprehensive Income	COMPREHENSIVE INCOME
	The components of comprehensive income, net of related tax, are as follows:
		Three Months Ended
		March 31,
		2015			2014
	Net income	$	40,343		$	34,524
	Other comprehensive income:
	Securities available for sale:
	Unrealized gains arising during the period, net of tax expense of $4,523 and $9,016		8,400			16,742
	Reclassification adjustment for losses (gains) included in net income, net of tax (benefit) expense of $(3) and $3,311		6			(6,150	)
	Derivative instruments:
	Unrealized gains arising during the period, net of tax expense of $1,504 and $1,402		2,793			2,603
	Reclassification adjustment for gains included in net income, net of tax expense of $283 and $285		(526	)		(529	)
	Pension and postretirement benefit obligations:
	Unrealized gains arising during the period, net of tax expense of $189 and $117		350			217
	Other comprehensive income		11,023			12,883
	Comprehensive income	$	51,366		$	47,407
	The amounts reclassified from AOCI related to securities available for sale are included in net securities (losses) gains on the Consolidated Statements of Comprehensive Income, while the amounts reclassified from AOCI related to derivative instruments are included in interest income on loans and leases on the Consolidated Statements of Comprehensive Income.
	The tax (benefit) expense amounts reclassified from AOCI in connection with the securities available for sale and derivative instruments reclassifications are included in income tax provision on the Consolidated Statements of Comprehensive Income.
	The following table presents changes in AOCI, net of tax, by component:
		Unrealized			Unrealized			Unrecognized			Total
		Net Gains			Net Gains			Pension and
		(Losses) on			(Losses) on			Postretirement
		Securities			Derivative			Obligations
		Available			Instruments
		for Sale
	Three Months Ended March 31, 2015
	Balance at beginning of period	$	(440	)	$	(143	)	$	(45,420	)	$	(46,003	)
	Other comprehensive income before reclassifications		8,400			2,793			350			11,543
	Amounts reclassified from AOCI		6			(526	)		—			(520	)
	Net current period other comprehensive income		8,406			2,267			350			11,023
	Balance at end of period	$	7,966		$	2,124		$	(45,070	)	$	(34,980	)

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Common Share	EARNINGS PER COMMON SHARE
	Basic earnings per common share is calculated by dividing net income available to common stockholders by the weighted average number of shares of common stock outstanding net of unvested shares of restricted stock.
	Diluted earnings per common share is calculated by dividing net income available to common stockholders by the weighted average number of shares of common stock outstanding, adjusted for the dilutive effect of potential common shares issuable for stock options, warrants and restricted shares, as calculated using the treasury stock method. Adjustments to the weighted average number of shares of common stock outstanding are made only when such adjustments dilute earnings per common share.
	The following table sets forth the computation of basic and diluted earnings per common share:
		Three Months Ended
		March 31,
		2015		2014
	Net income	$	40,343	$	34,524
	Less: Preferred stock dividends		2,010		2,322
	Net income available to common stockholders	$	38,333	$	32,202
	Basic weighted average common shares outstanding		174,152,283		162,186,395
	Net effect of dilutive stock options, warrants, restricted stock and convertible debt		1,673,693		1,780,851
	Diluted weighted average common shares outstanding		175,825,976		163,967,246
	Earnings per common share:
	Basic	$	0.22	$	0.2
	Diluted	$	0.22	$	0.2
	For the three months ended March 31, 2015 and 2014, 24,272 and 51,641 shares of common stock, respectively, related to stock options and warrants were excluded from the computation of diluted earnings per common share because the exercise price of the shares was greater than the average market price of the common shares and, therefore, the effect would be anti-dilutive.

Cash_Flow_Information

Cash Flow Information	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Cash Flow Information	CASH FLOW INFORMATION
	Following is a summary of supplemental cash flow information:
	Three Months Ended March 31	2015		2014
	Interest paid on deposits and other borrowings	$	11,626	$	10,576
	Income taxes paid		—		—
	Transfers of loans to other real estate owned		1,965		4,849
	Financing of other real estate owned sold		166		—

Business_Segments

Business Segments	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS
	The Corporation operates in four reportable segments: Community Banking, Wealth Management, Insurance and Consumer Finance.
		•		The Community Banking segment provides commercial and consumer banking services. Commercial banking solutions include corporate banking, small business banking, investment real estate financing, asset based lending, capital markets and lease financing. Consumer banking products and services include deposit products, mortgage lending, consumer lending and a complete suite of mobile and online banking services.
		•		The Wealth Management segment provides a broad range of personal and corporate fiduciary services including the administration of decedent and trust estates. In addition, it offers various alternative products, including securities brokerage and investment advisory services, mutual funds and annuities.
		•		The Insurance segment includes a full-service insurance agency offering all lines of commercial and personal insurance through major carriers. The Insurance segment also includes a reinsurer.
		•		The Consumer Finance segment primarily makes installment loans to individuals and purchases installment sales finance contracts from retail merchants. The Consumer Finance segment activity is funded through the sale of the Corporation’s subordinated notes at the finance company’s branch offices.
	The following tables provide financial information for these segments of the Corporation. The information provided under the caption “Parent and Other” represents operations not considered to be reportable segments and/or general operating expenses of the Corporation, and includes the parent company, other non-bank subsidiaries and eliminations and adjustments which are necessary for purposes of reconciliation to the consolidated amounts.
			Community		Wealth		Insurance			Consumer		Parent and			Consolidated
			Banking		Management					Finance		Other
	At or for the Three Months Ended March 31, 2015
	Interest income		$	122,118	$	—	$	23		$	9,593	$	1,635		$	133,369
	Interest expense			9,941		—		—			860		647			11,448
	Net interest income			112,177		—		23			8,733		988			121,921
	Provision for credit losses			6,327		—		—			1,574		235			8,136
	Non-interest income			27,301		8,387		3,593			676		(1,775	)		38,182
	Non-interest expense			77,079		6,493		4,170			4,808		(10	)		92,540
	Intangible amortization			1,947		68		100			—		—			2,115
	Income tax expense (benefit)			15,931		658		(226	)		1,149		(543	)		16,969
	Net income (loss)			38,194		1,168		(428	)		1,878		(469	)		40,343
	Total assets			16,100,851		21,125		18,464			182,662		(44,254	)		16,278,848
	Total intangibles			852,764		10,652		10,021			1,809		—			875,246
	At or for the Three Months Ended March 31, 2014
	Interest income		$	106,691	$	—	$	25		$	9,365	$	1,799		$	117,880
	Interest expense			8,248		—		—			846		961			10,055
	Net interest income			98,443		—		25			8,519		838			107,825
	Provision for credit losses			5,296		—		—			1,457		253			7,006
	Non-interest income			31,913		7,323		4,210			660		(2,036	)		42,070
	Non-interest expense			76,866		6,292		3,046			4,937		742			91,883
	Intangible amortization			2,110		72		101			—		—			2,283
	Income tax expense (benefit)			13,343		351		385			1,073		(953	)		14,199
	Net income (loss)			32,741		608		703			1,712		(1,240	)		34,524
	Total assets			14,299,543		19,542		19,954			182,018		(44,547	)		14,476,510
	Total intangibles			833,642		10,936		10,425			1,809		—			856,812

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS
	The Corporation uses fair value measurements to record fair value adjustments to certain financial assets and liabilities and to determine fair value disclosures. Securities available for sale and derivatives are recorded at fair value on a recurring basis. Additionally, from time to time, the Corporation may be required to record at fair value other assets on a non-recurring basis, such as mortgage loans held for sale, certain impaired loans, OREO and certain other assets.
	Fair value is defined as an exit price, representing the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value measurements are not adjusted for transaction costs. Fair value is a market-based measure considered from the perspective of a market participant who holds the asset or owes the liability rather than an entity-specific measure.
	In determining fair value, the Corporation uses various valuation approaches, including market, income and cost approaches. ASC 820, Fair Value Measurements and Disclosures, establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability, which are developed based on market data obtained from sources independent of the Corporation. Unobservable inputs reflect the Corporation’s assumptions about the assumptions that market participants would use in pricing an asset or liability, which are developed based on the best information available in the circumstances.
	The fair value hierarchy gives the highest priority to unadjusted quoted market prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). The fair value hierarchy is broken down into three levels based on the reliability of inputs as follows:
	Measurement	Definition
	Category
	Level 1	valuation is based upon unadjusted quoted market prices for identical instruments traded in active markets.
	Level 2	valuation is based upon quoted market prices for similar instruments traded in active markets, quoted market prices for identical or similar instruments traded in markets that are not active and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by market data.
	Level 3	valuation is derived from other valuation methodologies including discounted cash flow models and similar techniques that use significant assumptions not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in determining fair value.
	A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement.
	Following is a description of the valuation methodologies the Corporation uses for financial instruments recorded at fair value on either a recurring or non-recurring basis:
	Securities Available For Sale
	Securities available for sale consists of both debt and equity securities. These securities are recorded at fair value on a recurring basis. At March 31, 2015, 99.9% of these securities used valuation methodologies involving market-based or market-derived information, collectively Level 1 and Level 2 measurements, to measure fair value. The remaining 0.1% of these securities was measured using model-based techniques, with primarily unobservable (Level 3) inputs.
	The Corporation closely monitors market conditions involving assets that have become less actively traded. If the fair value measurement is based upon recent observable market activity of such assets or comparable assets (other than forced or distressed transactions) that occur in sufficient volume, and do not require significant adjustment using unobservable inputs, those assets are classified as Level 1 or Level 2; if not, they are classified as Level 3. Making this assessment requires significant judgment.
	The Corporation uses prices from independent pricing services and, to a lesser extent, indicative (non-binding) quotes from independent brokers, to measure the fair value of investment securities. The Corporation validates prices received from pricing services or brokers using a variety of methods, including, but not limited to, comparison to secondary pricing services, corroboration of pricing by reference to other independent market data such as secondary broker quotes and relevant benchmark indices, and review of pricing information by Corporate personnel familiar with market liquidity and other market-related conditions.
	Derivative Financial Instruments
	The Corporation determines its fair value for derivatives using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects contractual terms of the derivative, including the period to maturity and uses observable market based inputs, including interest rate curves and implied volatilities.
	The Corporation incorporates credit valuation adjustments to appropriately reflect both its own non-performance risk and the respective counterparty’s non-performance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of non-performance risk, the Corporation considers the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees.
	Although the Corporation has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of March 31, 2015, the Corporation has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Corporation has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.
	Residential Mortgage Loans Held For Sale
	These loans are carried at the lower of cost or fair value. Under lower of cost or fair value accounting, periodically, it may be necessary to record non-recurring fair value adjustments. Fair value, when recorded, is based on independent quoted market prices and is classified as Level 2.
	Impaired Loans
	The Corporation reserves for commercial loan relationships greater than or equal to $500 that the Corporation considers impaired as defined in ASC 310 at the time the Corporation identifies the loan as impaired based upon the present value of expected future cash flows available to pay the loan, or based upon the fair value of the collateral less estimated selling costs where a loan is collateral dependent. Collateral may be real estate and/or business assets including equipment, inventory and accounts receivable.
	The Corporation determines the fair value of real estate based on appraisals by licensed or certified appraisers. The value of business assets is generally based on amounts reported on the business’ financial statements. Management must rely on the financial statements prepared and certified by the borrower or its accountants in determining the value of these business assets on an ongoing basis, which may be subject to significant change over time. Based on the quality of information or statements provided, management may require the use of business asset appraisals and site-inspections to better value these assets. The Corporation may discount appraised and reported values based on management’s historical knowledge, changes in market conditions from the time of valuation or management’s knowledge of the borrower and the borrower’s business. Since not all valuation inputs are observable, the Corporation classifies these non-recurring fair value determinations as Level 2 or Level 3 based on the lowest level of input that is significant to the fair value measurement.
	The Corporation reviews and evaluates impaired loans no less frequently than quarterly for additional impairment based on the same factors identified above.
	Other Real Estate Owned
	OREO is comprised of commercial and residential real estate properties obtained in partial or total satisfaction of loan obligations plus some bank owned real estate. OREO acquired in settlement of indebtedness is recorded at the lower of carrying amount of the loan or fair value less costs to sell. Subsequently, these assets are carried at the lower of carrying value or fair value less costs to sell. Accordingly, it may be necessary to record non-recurring fair value adjustments. Fair value is generally based upon appraisals by licensed or certified appraisers and other market information and is classified as Level 2 or Level 3.
	The following table presents the balances of assets and liabilities measured at fair value on a recurring basis:
		Level 1			Level 2			Level 3			Total
	March 31, 2015
	Assets Measured at Fair Value
	Available for sale debt securities:
	U.S. Treasury	$	—		$	29,937		$	—		$	29,937
	U.S. government-sponsored entities		—			390,660			—			390,660
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		—			505,561			—			505,561
	Agency collateralized mortgage obligations		—			572,017			—			572,017
	Non-agency collateralized mortgage obligations		—			10			1,354			1,364
	Commercial mortgage-backed securities		—			6,843			—			6,843
	States of the U.S. and political subdivisions		—			13,175			—			13,175
	Other debt securities		—			16,231			—			16,231
			—			1,534,434			1,354			1,535,788
	Available for sale equity securities:
	Financial services industry		91			645			435			1,171
	Insurance services industry		121			—			—			121
			212			645			435			1,292
			212			1,535,079			1,789			1,537,080
	Derivative financial instruments:
	Trading		—			53,614			—			53,614
	Not for trading		—			3,937			—			3,937
			—			57,551			—			57,551
		$	212		$	1,592,630		$	1,789		$	1,594,631
	Liabilities Measured at Fair Value
	Derivative financial instruments:
	Trading		—		$	53,762			—		$	53,762
	Not for trading		—			669			—			669
			—		$	54,431			—		$	54,431
		Level 1			Level 2			Level 3			Total
	December 31, 2014
	Assets Measured at Fair Value
	Available for sale debt securities:
	U.S. Treasury	$	—		$	29,682		$	—		$	29,682
	U.S. government-sponsored entities		—			337,133			—			337,133
Residential mortgage-backed securities:
Agency mortgage-backed securities		—			554,085			—			554,085
Agency collateralized mortgage obligations		—			573,171			—			573,171
Non-agency collateralized mortgage obligations		—			11			1,420			1,431
Commercial mortgage-backed securities		—			7,880			—			7,880
States of the U.S. and political subdivisions		—			13,158			—			13,158
Other debt securities		—			16,178			—			16,178
		—			1,531,298			1,420			1,532,718
Available for sale equity securities:
Financial services industry		99			654			475			1,228
Insurance services industry		119			—			—			119
		218			654			475			1,347
		218			1,531,952			1,895			1,534,065
Derivative financial instruments:
Trading		—			43,789			—			43,789
Not for trading		—			2,109			—			2,109
		—			45,898			—			45,898
	$	218		$	1,577,850		$	1,895		$	1,579,963
Liabilities Measured at Fair Value
Derivative financial instruments:
Trading		—		$	43,830			—		$	43,830
Not for trading		—			2,330			—			2,330
		—		$	46,160			—		$	46,160
There were no transfers of assets or liabilities between the hierarchy levels for 2015 or 2014.
The following table presents additional information about assets measured at fair value on a recurring basis and for which the Corporation has utilized Level 3 inputs to determine fair value:
	Pooled Trust			Equity			Residential			Total
	Preferred			Securities			Non-Agency
	Collateralized						Collateralized
	Debt						Mortgage
	Obligations						Obligations
Three Months Ended March 31, 2015
Balance at beginning of period		—		$	475		$	1,420		$	1,895
Total gains (losses) – realized/unrealized:
Included in earnings		—			—			—			—
Included in other comprehensive income		—			(40	)		(12	)		(52	)
Accretion included in earnings		—			—			1			1
Purchases, issuances, sales and settlements:
Purchases		—			—			—			—
Issuances		—			—			—			—
Sales/redemptions		—			—			—			—
Settlements		—			—			(55	)		(55	)
Transfers from Level 3		—			—			—			—
Transfers into Level 3		—			—			—			—
Balance at end of period		—		$	435		$	1,354		$	1,789
Year Ended December 31, 2014
Balance at beginning of period	$	31,595		$	410		$	1,744		$	33,749
Total gains (losses) – realized/unrealized:
Included in earnings		13,766			—			—			13,766
Included in other comprehensive income		5,608			65			3			5,676
Accretion included in earnings		657			—			5			662
Purchases, issuances, sales and settlements:
Purchases		—			—			—			—
Issuances		—			—			—			—
Sales/redemptions		(51,527	)		—			—			(51,527	)
Settlements		(99	)		—			(332	)		(431	)
Transfers from Level 3		—			—			—			—
Transfers into Level 3		—			—			—			—
Balance at end of period	$	—		$	475		$	1,420		$	1,895
The Corporation reviews fair value hierarchy classifications on a quarterly basis. Changes in the observability of the valuation attributes may result in reclassification of certain financial assets or liabilities. Such reclassifications are reported as transfers in/out of Level 3 at fair value at the beginning of the period in which the changes occur. See the Securities footnote in the Notes to Consolidated Financial Statements section of this Report for information relating to significant unobservable inputs used in determining Level 3 fair values.
For the three months ended March 31, 2015 and 2014, there were no gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets still held as of those dates. The total (losses) gains included in earnings are in the net securities (losses) gains line item in the Consolidated Statements of Comprehensive Income.
In accordance with GAAP, from time to time, the Corporation measures certain assets at fair value on a non-recurring basis. These adjustments to fair value usually result from the application of the lower of cost or fair value accounting or write-downs of individual assets. Valuation methodologies used to measure these fair value adjustments were previously described. For assets measured at fair value on a non-recurring basis still held at the balance sheet date, the following table provides the hierarchy level and the fair value of the related assets or portfolios:
	Level 1			Level 2			Level 3			Total
March 31, 2015
Impaired loans		—		$	190		$	693		$	883
Other real estate owned		—			977			1,433			2,410
December 31, 2014
Impaired loans		—			177			1,528			1,705
Other real estate owned		—			5,695			2,365			8,060
Impaired loans measured or re-measured at fair value on a non-recurring basis during the three months ended March 31, 2015 had a carrying amount of $2,940 and an allocated allowance for credit losses of $2,181. The allocated allowance is based on fair value of $883 less estimated costs to sell of $124. The allowance for credit losses includes a provision applicable to the current period fair value measurements of $1,002, which was included in the provision for credit losses for the three months ended March 31, 2015.
OREO with a carrying amount of $2,501 was written down to $2,140 (fair value of $2,410 less estimated costs to sell of $270), resulting in a loss of $361, which was included in earnings for the three months ended March 31, 2015.
Fair Value of Financial Instruments
The following methods and assumptions were used to estimate the fair value of each financial instrument:
Cash and Cash Equivalents, Accrued Interest Receivable and Accrued Interest Payable. For these short-term instruments, the carrying amount is a reasonable estimate of fair value.
Securities. For both securities available for sale and securities held to maturity, fair value equals the quoted market price from an active market, if available, and is classified within Level 1. If a quoted market price is not available, fair value is estimated using quoted market prices for similar securities or pricing models, and is classified as Level 2. Where there is limited market activity or significant valuation inputs are unobservable, securities are classified within Level 3. Under current market conditions, assumptions used to determine the fair value of Level 3 securities have greater subjectivity due to the lack of observable market transactions.
Loans and Leases. The fair value of fixed rate loans and leases is estimated by discounting the future cash flows using the current rates at which similar loans and leases would be made to borrowers with similar credit ratings and for the same remaining maturities less an illiquidity discount. The fair value of variable and adjustable rate loans and leases approximates the carrying amount. Due to the significant judgment involved in evaluating credit quality, loans and leases are classified within Level 3 of the fair value hierarchy.
Derivative Assets and Liabilities. The Corporation determines its fair value for derivatives using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects contractual terms of the derivative, including the period to maturity and uses observable market based inputs, including interest rate curves and implied volatilities.
The Corporation incorporates credit valuation adjustments to appropriately reflect both its own non-performance risk and the respective counterparty’s non-performance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of non-performance risk, the Corporation considers the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees.
Although the Corporation has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of March 31, 2015, the Corporation has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Corporation has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.
Deposits. The estimated fair value of demand deposits, savings accounts and certain money market deposits is the amount payable on demand at the reporting date because of the customers’ ability to withdraw funds immediately. The fair value of fixed-maturity deposits is estimated by discounting future cash flows using rates currently offered for deposits of similar remaining maturities.
Short-Term Borrowings. The carrying amounts for short-term borrowings approximate fair value for amounts that mature in 90 days or less. The fair value of subordinated notes is estimated by discounting future cash flows using rates currently offered.
Long-Term Borrowings. The fair value of long-term borrowings is estimated by discounting future cash flows based on the market prices for the same or similar issues or on the current rates offered to the Corporation for debt of the same remaining maturities.
Loan Commitments and Standby Letters of Credit. Estimates of the fair value of these off-balance sheet items were not made because of the short-term nature of these arrangements and the credit standing of the counterparties. Also, unfunded loan commitments relate principally to variable rate commercial loans, typically are non-binding, and fees are not normally assessed on these balances.
Nature of Estimates. Many of the estimates presented herein are based upon the use of highly subjective information and assumptions and, accordingly, the results may not be precise. Management believes that fair value estimates may not be comparable to other financial institutions due to the wide range of permitted valuation techniques and numerous estimates which must be made. Further, because the disclosed fair value amounts were estimated as of the balance sheet date, the amounts actually realized or paid upon maturity or settlement of the various financial instruments could be significantly different.
The fair values of the Corporation’s financial instruments are as follows:
							Fair Value Measurements
	Carrying			Fair Value			Level 1			Level 2			Level 3
	Amount
March 31, 2015
Financial Assets
Cash and cash equivalents	$	234,246		$	234,246		$	234,246		$	—		$	—
Securities available for sale		1,537,080			1,537,080			212			1,535,079			1,789
Securities held to maturity		1,513,204			1,536,449			—			1,532,588			3,861
Net loans and leases, including loans held for sale		11,280,221			11,119,711			—			—			11,119,711
Derivative assets		57,551			57,551			—			57,551			—
Accrued interest receivable		41,935			41,935			41,935			—			—
Financial Liabilities
Deposits		11,806,043			11,812,401			9,217,159			2,595,242			—
Short-term borrowings		1,740,500			1,740,499			1,740,499			—			—
Long-term borrowings		541,474			541,955			—			—			541,955
Derivative liabilities		54,431			54,431			—			54,431			—
Accrued interest payable		6,511			6,511			6,511			—			—
December 31, 2014
Financial Assets
Cash and cash equivalents	$	287,393		$	287,393		$	287,393		$	—		$	—
Securities available for sale		1,534,065			1,534,065			218			1,531,952			1,895
Securities held to maturity		1,453,355			1,468,258			—			1,463,945			4,313
Net loans and leases, including loans held for sale		11,127,292			10,956,544			—			—			10,956,544
Derivative assets		45,898			45,898			—			45,898			—
Accrued interest receivable		40,231			40,231			40,231			—			—
Financial Liabilities
Deposits		11,382,208			11,382,402			8,771,173			2,611,229			—
Short-term borrowings		2,041,658			2,041,672			2,041,672			—			—
Long-term borrowings		541,443			539,007			—			—			539,007
Derivative liabilities		46,160			46,160			—			46,160			—
Accrued interest payable		6,689			6,689			6,689			—			—

New_Accounting_Standards_Polic

New Accounting Standards (Policies)	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Cloud Computing Arrangements	Cloud Computing Arrangements
	In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-05, Intangibles-Goodwill and Other-Internal-Use Software. ASU 2015-05 provides guidance to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement environment. The amendments in this Update provide a basis for evaluating whether a cloud computing arrangement includes a software license to internal-use software, and how to account for the software license element of the arrangement. This update supersedes the existing requirement to analogize to operating lease guidance in accounting for some software licenses. The requirements of ASU 2015-05 are effective for reporting periods beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply ASU 2015-05 either prospectively or retrospectively. The Corporation is evaluating this new guidance and has not yet determined which approach it will adopt to apply the amendments in ASU 2015-05 or the impact that the adoption of this update will have on its financial statements.
Consolidation	Consolidation
	In February 2015, the FASB issued ASU No. 2015-02, Consolidation. ASU 2015-02 changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. This update modifies the evaluation of whether limited partnerships or similar legal entities are variable interest entities (VIEs) or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership and affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The requirements of ASU 2015-02 are effective for reporting periods beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply ASU 2015-02 either retrospectively or by using a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption. The adoption of this update is not expected to have a material effect on the financial statements, results of operations or liquidity of the Corporation.
Income Statement	Income Statement
	In January 2015, the FASB issued ASU No. 2015-01, Income Statement – Extraordinary and Unusual Items. The FASB issued ASU 2015-01 as part of its Simplification Initiative to reduce complexity in accounting standards. ASU 2015-01 eliminates from GAAP the concept of extraordinary items. The requirements of ASU 2015-01 are effective for reporting periods beginning after December 15, 2015, with early adoption permitted. A reporting entity may apply ASU 2015-01 prospectively, or retrospectively to all prior periods presented in the financial statements. The adoption of this update will not have an effect on the financial statements, results of operations or liquidity of the Corporation, as the Corporation has not reported extraordinary items.

Securities_Tables

Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost and Fair Value of Securities Available for Sale	The amortized cost and fair value of securities are as follows:
		Amortized			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized
					Gains			Losses
	Securities Available for Sale
	March 31, 2015
	U.S. Treasury	$	29,637		$	300		$	—		$	29,937
	U.S. government-sponsored entities		388,363			2,818			(521	)		390,660
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		494,497			11,064			—			505,561
	Agency collateralized mortgage obligations		573,738			3,646			(5,367	)		572,017
	Non-agency collateralized mortgage obligations		1,359			5			—			1,364
	Commercial mortgage-backed securities		6,844			—			(1	)		6,843
	States of the U.S. and political subdivisions		12,713			476			(14	)		13,175
	Other debt securities		16,643			373			(785	)		16,231
	Total debt securities		1,523,794			18,682			(6,688	)		1,535,788
	Equity securities		1,031			261			—			1,292
		$	1,524,825		$	18,943		$	(6,688	)	$	1,537,080
	December 31, 2014
	U.S. Treasury	$	29,604		$	78		$	—		$	29,682
	U.S. government-sponsored entities		338,330			742			(1,939	)		337,133
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		546,572			7,548			(35	)		554,085
	Agency collateralized mortgage obligations		580,601			1,617			(9,047	)		573,171
	Non-agency collateralized mortgage obligations		1,414			17			—			1,431
	Commercial mortgage-backed securities		7,891			—			(11	)		7,880
	States of the U.S. and political subdivisions		12,713			477			(32	)		13,158
	Other debt securities		16,615			420			(857	)		16,178
	Total debt securities		1,533,740			10,899			(11,921	)		1,532,718
	Equity securities		1,031			316			—			1,347
		$	1,534,771		$	11,215		$	(11,921	)	$	1,534,065
Schedule of Amortized Cost and Fair Value of Securities Held to Maturity
		Amortized			Gross			Gross			Fair Value
		Cost			Unrealized			Unrealized
					Gains			Losses
	Securities Available for Sale
	March 31, 2015
	U.S. Treasury	$	29,637		$	300		$	—		$	29,937
	U.S. government-sponsored entities		388,363			2,818			(521	)		390,660
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		494,497			11,064			—			505,561
	Agency collateralized mortgage obligations		573,738			3,646			(5,367	)		572,017
	Non-agency collateralized mortgage obligations		1,359			5			—			1,364
	Commercial mortgage-backed securities		6,844			—			(1	)		6,843
	States of the U.S. and political subdivisions		12,713			476			(14	)		13,175
	Other debt securities		16,643			373			(785	)		16,231
	Total debt securities		1,523,794			18,682			(6,688	)		1,535,788
	Equity securities		1,031			261			—			1,292
		$	1,524,825		$	18,943		$	(6,688	)	$	1,537,080
	December 31, 2014
	U.S. Treasury	$	29,604		$	78		$	—		$	29,682
	U.S. government-sponsored entities		338,330			742			(1,939	)		337,133
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		546,572			7,548			(35	)		554,085
	Agency collateralized mortgage obligations		580,601			1,617			(9,047	)		573,171
	Non-agency collateralized mortgage obligations		1,414			17			—			1,431
	Commercial mortgage-backed securities		7,891			—			(11	)		7,880
	States of the U.S. and political subdivisions		12,713			477			(32	)		13,158
	Other debt securities		16,615			420			(857	)		16,178
	Total debt securities		1,533,740			10,899			(11,921	)		1,532,718
	Equity securities		1,031			316			—			1,347
		$	1,534,771		$	11,215		$	(11,921	)	$	1,534,065
	Securities Held to Maturity
	March 31, 2015
	U.S. Treasury	$	500		$	182		$	—		$	682
	U.S. government-sponsored entities		146,578			1,731			(149	)		148,160
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		674,101			19,130			(20	)		693,211
	Agency collateralized mortgage obligations		505,859			3,633			(4,884	)		504,608
	Non-agency collateralized mortgage obligations		3,840			21			—			3,861
	Commercial mortgage-backed securities		17,484			385			—			17,869
	States of the U.S. and political subdivisions		164,842			3,372			(156	)		168,058
		$	1,513,204		$	28,454		$	(5,209	)	$	1,536,449
	December 31, 2014
	U.S. Treasury	$	502		$	168		$	—		$	670
	U.S. government-sponsored entities		101,602			885			(524	)		101,963
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		677,169			16,712			(346	)		693,535
	Agency collateralized mortgage obligations		501,965			1,858			(7,329	)		496,494
	Non-agency collateralized mortgage obligations		4,285			28			—			4,313
	Commercial mortgage-backed securities		17,560			179			—			17,739
	States of the U.S. and political subdivisions		150,272			3,315			(43	)		153,544
		$	1,453,355		$	23,145		$	(8,242	)	$	1,468,258
Gross Gains and Gross Losses Realized on Sales of Securities	Gross gains and gross losses were realized on securities as follows:
		Three Months Ended
		March 31,
		2015			2014
	Gross gains	$	—		$	18,009
	Gross losses		(9	)		(8,548	)
		$	(9	)	$	9,461
Amortized Cost and Fair Value of Securities, by Contractual Maturities	As of March 31, 2015, the amortized cost and fair value of securities, by contractual maturities, were as follows:
		Available for Sale						Held to Maturity
		Amortized			Fair			Amortized			Fair
		Cost			Value			Cost			Value
	Due in one year or less	$	4,985		$	5,069		$	1,282		$	1,285
	Due from one to five years		423,890			426,811			138,269			139,139
	Due from five to ten years		11,591			12,018			72,457			74,672
	Due after ten years		6,890			6,105			99,912			101,804
			447,356			450,003			311,920			316,900
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		494,497			505,561			674,101			693,211
	Agency collateralized mortgage obligations		573,738			572,017			505,859			504,608
	Non-agency collateralized mortgage obligations		1,359			1,364			3,840			3,861
	Commercial mortgage-backed securities		6,844			6,843			17,484			17,869
	Equity securities		1,031			1,292			—			—
		$	1,524,825		$	1,537,080		$	1,513,204		$	1,536,449
Summaries of Fair Values and Unrealized Losses of Securities, Segregated by Length of Impairment	Following are summaries of the fair values and unrealized losses of securities, segregated by length of impairment:
		Less than 12 Months									12 Months or More							Total
		#			Fair			Unrealized			#		Fair		Unrealized			#		Fair		Unrealized
					Value			Losses					Value		Losses					Value		Losses
	Securities Available for Sale
	March 31, 2015
	U.S. government-sponsored entities		3		$	59,857		$	(142	)		5	$	55,612	$	(379	)		8	$	115,469	$	(521	)
	Residential mortgage-backed securities:
	Agency collateralized mortgage obligations		4			61,998			(199	)		17		242,124		(5,168	)		21		304,122		(5,367	)
	Commercial mortgage-backed securities		1			6,843			(1	)		—		—		—			1		6,843		(1	)
	States of the U.S. and political subdivisions		—			—			—			1		1,177		(14	)		1		1,177		(14	)
	Other debt securities		—			—			—			4		6,105		(785	)		4		6,105		(785	)
			8		$	128,698		$	(342	)		27	$	305,018	$	(6,346	)		35	$	433,716	$	(6,688	)
	December 31, 2014
	U.S. government-sponsored entities		7		$	89,986		$	(275	)		7	$	99,326	$	(1,664	)		14	$	189,312	$	(1,939	)
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		2			45,145			(35	)		—		—		—			2		45,145		(35	)
	Agency collateralized mortgage obligations		9			166,908			(1,238	)		16		225,700		(7,809	)		25		392,608		(9,047	)
	Commercial mortgage-backed securities		1			7,880			(11	)		—		—		—			1		7,880		(11	)
	States of the U.S. and political subdivisions		—			—			—			1		1,159		(32	)		1		1,159		(32	)
	Other debt securities		—			—			—			4		6,030		(857	)		4		6,030		(857	)
			19		$	309,919		$	(1,559	)		28	$	332,215	$	(10,362	)		47	$	642,134	$	(11,921	)
	Securities Held to Maturity
	March 31, 2015
	U.S. government-sponsored entities		1		$	14,970		$	(30	)		1	$	14,881	$	(119	)		2	$	29,851	$	(149	)
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		—			—			—			1		1,234		(20	)		1		1,234		(20	)
	Agency collateralized mortgage obligations		4			69,926			(402	)		14		185,466		(4,482	)		18		255,392		(4,884	)
	States of the U.S. and political subdivisions		8			13,418			(156	)		—		—		—			8		13,418		(156	)
			13		$	98,314		$	(588	)		16	$	201,581	$	(4,621	)		29	$	299,895	$	(5,209	)
	December 31, 2014
	U.S. government-sponsored entities		2		$	24,989		$	(40	)		2	$	29,516	$	(484	)		4	$	54,505	$	(524	)
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		1			1,099			(1	)		4		45,042		(345	)		5		46,141		(346	)
	Agency collateralized mortgage obligations		8			104,071			(630	)		14		189,642		(6,699	)		22		293,713		(7,329	)
	States of the U.S. and political subdivisions		1			1,427			(4	)		4		5,453		(39	)		5		6,880		(43	)
			12		$	131,586		$	(675	)		24	$	269,653	$	(7,567	)		36	$	401,239	$	(8,242	)
Summary of Cumulative Credit-Related OTTI Charges	The following table presents a summary of the cumulative credit-related OTTI charges recognized as components of earnings for securities for which a portion of an OTTI is recognized in other comprehensive income:
		Collateralized			Equities			Total
		Debt
		Obligations
	For the Three Months Ended March 31, 2015
	Beginning balance		—		$	27		$	27
	Loss where impairment was not previously recognized		—			—			—
	Additional loss where impairment was previously recognized		—			—			—
	Reduction due to credit impaired securities sold		—			—			—
	Ending balance		—		$	27		$	27
	For the Three Months Ended March 31, 2014
	Beginning balance	$	17,155		$	27		$	17,182
	Loss where impairment was not previously recognized		—			—			—
	Additional loss where impairment was previously recognized		—			—			—
	Reduction due to credit impaired securities sold		(17,155	)		—			(17,155	)
	Ending balance	$	—		$	27		$	27

Loans_and_Leases_Tables

Loans and Leases (Tables)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Summary of Loans and Leases, Net of Unearned Income	Following is a summary of loans and leases, net of unearned income:
			Originated			Acquired			Total
			Loans			Loans			Loans and
									Leases
	March 31, 2015
	Commercial real estate		$	3,082,385		$	734,804		$	3,817,189
	Commercial and industrial			2,281,075			116,656			2,397,731
	Commercial leases			180,207			—			180,207
	Total commercial loans and leases			5,543,667			851,460			6,395,127
	Direct installment			1,594,846			58,775			1,653,621
	Residential mortgages			877,437			421,660			1,299,097
	Indirect installment			903,780			1,424			905,204
	Consumer lines of credit			953,569			154,849			1,108,418
	Other			42,632			—			42,632
			$	9,915,931		$	1,488,168		$	11,404,099
	December 31, 2014
	Commercial real estate		$	3,031,810		$	783,898		$	3,815,708
	Commercial and industrial			2,197,793			120,222			2,318,015
	Commercial leases			177,824			—			177,824
	Total commercial loans and leases			5,407,427			904,120			6,311,547
	Direct installment			1,579,770			64,851			1,644,621
	Residential mortgages			817,586			445,467			1,263,053
	Indirect installment			873,645			1,906			875,551
	Consumer lines of credit			946,427			164,549			1,110,976
	Other			41,290			—			41,290
			$	9,666,145		$	1,580,893		$	11,247,038
Summary of Outstanding Principal Balance and Carrying Amount of Acquired Loans	The outstanding balance and the carrying amount of acquired loans included in the consolidated balance sheet are as follows:
			March 31,			December 31,
			2015			2014
	Accounted for under ASC 310-30:
	Outstanding balance		$	1,513,616		$	1,597,558
	Carrying amount			1,259,995			1,344,171
	Accounted for under ASC 310-20:
	Outstanding balance			232,524			242,488
	Carrying amount			220,921			228,748
	Total acquired loans:
	Outstanding balance			1,746,140			1,840,046
	Carrying amount			1,480,916			1,572,919
Summary of Change in Accretable Yield of Acquired Loans	The following table provides changes in accretable yield for all acquired loans accounted for under ASC 310-30. Loans accounted for under ASC 310-20 are not included in this table.
			Three Months Ended
			March 31,
			2015			2014
	Balance at beginning of period		$	331,899		$	305,646
	Reduction due to unexpected early payoffs			(11,909	)		(12,694	)
	Reclass from non-accretable difference			7,676			768
	Disposals/transfers			(118	)		(944	)
	Accretion			(16,264	)		(15,913	)
	Balance at end of period		$	311,284		$	276,863
Summary of Non-Performing Assets	Following is a summary of non-performing assets:
			March 31,			December 31,
			2015			2014
	Non-accrual loans		$	45,029		$	45,113
	Troubled debt restructurings			22,022			23,439
	Total non-performing loans			67,051			68,552
	Other real estate owned (OREO)			40,796			41,466
	Total non-performing assets		$	107,847		$	110,018
	Asset quality ratios:
	Non-performing loans as a percent of total loans and leases			0.59	%		0.61	%
	Non-performing loans + OREO as a percent of total loans and leases + OREO			0.94	%		0.97	%
	Non-performing assets as a percent of total assets			0.66	%		0.68	%
Age Analysis of Past Due Loans, by Class	The following tables provide an analysis of the aging of the Corporation’s past due loans by class, segregated by loans and leases originated and loans acquired:
			30-89 Days			> 90 Days			Non-Accrual		Total		Current			Total
			Past Due			Past Due and					Past Due					Loans and
						Still Accruing										Leases
	Originated Loans and Leases
	March 31, 2015
	Commercial real estate		$	6,655		$	130		$	23,653	$	30,438	$	3,051,947		$	3,082,385
	Commercial and industrial			2,939			3			8,846		11,788		2,269,287			2,281,075
	Commercial leases			1,097			—			732		1,829		178,378			180,207
	Total commercial loans and leases			10,691			133			33,231		44,055		5,499,612			5,543,667
	Direct installment			8,748			3,575			6,464		18,787		1,576,059			1,594,846
	Residential mortgages			7,040			1,731			3,625		12,396		865,041			877,437
	Indirect installment			5,015			409			1,111		6,535		897,245			903,780
	Consumer lines of credit			2,501			656			598		3,755		949,814			953,569
	Other			47			39			—		86		42,546			42,632
			$	34,042		$	6,543		$	45,029	$	85,614	$	9,830,317		$	9,915,931
	December 31, 2014
	Commercial real estate		$	9,601		$	313		$	24,132	$	34,046	$	2,997,764		$	3,031,810
	Commercial and industrial			2,446			3			8,310		10,759		2,187,034			2,197,793
	Commercial leases			961			43			722		1,726		176,098			177,824
	Total commercial loans and leases			13,008			359			33,164		46,531		5,360,896			5,407,427
	Direct installment			9,333			3,617			7,117		20,067		1,559,703			1,579,770
	Residential mortgages			8,709			3,891			2,964		15,564		802,022			817,586
	Indirect installment			7,804			684			1,149		9,637		864,008			873,645
	Consumer lines of credit			2,408			562			719		3,689		942,738			946,427
	Other			13			135			—		148		41,142			41,290
			$	41,275		$	9,248		$	45,113	$	95,636	$	9,570,509		$	9,666,145
			30-89			> 90 Days			Total		Current		Discount			Total
			Days			Past Due			Past							Loans
			Past Due			and Still			Due (1) (2)
						Accruing
	Acquired Loans
	March 31, 2015
	Commercial real estate		$	8,813		$	12,445		$	21,258	$	753,073	$	(39,527	)	$	734,804
	Commercial and industrial			1,023			1,651			2,674		122,604		(8,622	)		116,656
	Total commercial loans			9,836			14,096			23,932		875,677		(48,149	)		851,460
	Direct installment			1,199			1,112			2,311		55,476		988			58,775
	Residential mortgages			7,695			18,535			26,230		434,061		(38,631	)		421,660
	Indirect installment			9			17			26		1,648		(250	)		1,424
	Consumer lines of credit			1,115			2,146			3,261		156,676		(5,088	)		154,849
			$	19,854		$	35,906		$	55,760	$	1,523,538	$	(91,130	)	$	1,488,168
	December 31, 2014
	Commercial real estate		$	12,076		$	12,368		$	24,444	$	799,991	$	(40,537	)	$	783,898
	Commercial and industrial			687			1,968			2,655		127,535		(9,968	)		120,222
	Total commercial loans			12,763			14,336			27,099		927,526		(50,505	)		904,120
	Direct installment			2,670			1,443			4,113		59,532		1,206			64,851
	Residential mortgages			8,159			19,936			28,095		456,810		(39,438	)		445,467
	Indirect installment			38			30			68		2,179		(341	)		1,906
	Consumer lines of credit			1,048			2,279			3,327		166,912		(5,690	)		164,549
			$	24,678		$	38,024		$	62,702	$	1,612,959	$	(94,768	)	$	1,580,893
	-1	Past due information for acquired loans is based on the contractual balance outstanding at March 31, 2015 and December 31, 2014.
	-2	Acquired loans are considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if the Corporation can reasonably estimate the timing and amount of expected cash flows on such loans. Accordingly, the Corporation does not consider acquired contractually delinquent loans to be non-accrual or non-performing and continues to recognize interest income on these loans using the accretion method.
Summary of Commercial Loans and Leases by Credit Quality	The following tables present a summary of the Corporation’s commercial loans and leases by credit quality category, segregated by loans and leases originated and loans acquired:
			Commercial Loan and Lease Credit Quality Categories
			Pass			Special			Substandard		Doubtful		Total
						Mention
	Originated Loans and Leases
	March 31, 2015
	Commercial real estate		$	2,960,542		$	52,926		$	68,182	$	735	$	3,082,385
	Commercial and industrial			2,190,066			53,482			36,081		1,446		2,281,075
	Commercial leases			177,091			2,222			894		—		180,207
			$	5,327,699		$	108,630		$	105,157	$	2,181	$	5,543,667
	December 31, 2014
	Commercial real estate		$	2,890,830		$	58,630		$	81,951	$	399	$	3,031,810
	Commercial and industrial			2,085,893			71,420			39,684		796		2,197,793
	Commercial leases			174,677			2,198			949		—		177,824
			$	5,151,400		$	132,248		$	122,584	$	1,195	$	5,407,427
	Acquired Loans
	March 31, 2015
	Commercial real estate		$	579,462		$	64,892		$	90,450		—	$	734,804
	Commercial and industrial			102,974			2,411			11,271		—		116,656
			$	682,436		$	67,303		$	101,721		—	$	851,460
	December 31, 2014
	Commercial real estate		$	610,260		$	73,891		$	99,747		—	$	783,898
	Commercial and industrial			103,862			3,506			12,854		—		120,222
			$	714,122		$	77,397		$	112,601		—	$	904,120
Summary of Consumer Loans by Payment Status	Following is a table showing originated consumer loans by payment status:
			Consumer Loan Credit Quality
			by Payment Status
			Performing			Non-Performing			Total
	March 31, 2015
	Direct installment		$	1,581,078		$	13,768		$	1,594,846
	Residential mortgages			862,965			14,472			877,437
	Indirect installment			902,515			1,265			903,780
	Consumer lines of credit			951,980			1,589			953,569
	Other			42,632			—			42,632
	December 31, 2014
	Direct installment		$	1,565,090		$	14,680		$	1,579,770
	Residential mortgages			802,522			15,064			817,586
	Indirect installment			872,340			1,305			873,645
	Consumer lines of credit			944,631			1,796			946,427
	Other			41,290			—			41,290
Summary of Impaired Loans and Leases, by Class	Following is a summary of information pertaining to originated loans and leases considered to be impaired, by class of loan and lease:
			Unpaid			Recorded			Recorded		Total		Specific			Average
			Contractual			Investment			Investment		Recorded		Reserve			Recorded
			Principal			With No			With		Investment					Investment
			Balance			Specific			Specific
						Reserve			Reserve
	At or for the Three Months Ended March 31, 2015
	Commercial real estate		$	34,483		$	25,015		$	1,012	$	26,027	$	735		$	26,176
	Commercial and industrial			11,251			8,138			1,928		10,066		1,446			9,811
	Commercial leases			732			732			—		732		—			727
	Total commercial loans and leases			46,466			33,885			2,940		36,825		2,181			36,714
	Direct installment			13,977			13,768			—		13,768		—			14,343
	Residential mortgages			15,718			14,472			—		14,472		—			15,547
	Indirect installment			1,425			1,265			—		1,265		—			1,363
	Consumer lines of credit			1,600			1,589			—		1,589		—			1,696
	Other			—			—			—		—		—			—
			$	79,186		$	64,979		$	2,940	$	67,919	$	2,181		$	69,663
	At or for the Year Ended December 31, 2014
	Commercial real estate		$	34,583		$	25,443		$	883	$	26,326	$	399		$	30,807
	Commercial and industrial			11,412			7,609			1,948		9,557		780			9,510
	Commercial leases			722			722			—		722		—			686
	Total commercial loans and leases			46,717			33,774			2,831		36,605		1,179			41,003
	Direct installment			14,987			14,680			—		14,680		—			14,248
	Residential mortgages			16,791			15,064			—		15,064		—			16,924
	Indirect installment			1,467			1,305			—		1,305		—			1,399
	Consumer lines of credit			1,803			1,796			—		1,796		—			1,793
	Other			—			—			—		—		—			—
			$	81,765		$	66,619		$	2,831	$	69,450	$	1,179		$	75,367
Summary of Payment Status of Total TDRs	Following is a summary of the payment status of total TDRs:
			March 31,			December 31,
			2015			2014
	Accruing:
	Performing		$	12,793		$	9,441
	Non-performing			22,022			23,439
	Non-accrual			8,040			8,272
			$	42,855		$	41,152
Summary of Troubled Debt Restructurings by Class of Loans	The majority of TDRs are the result of interest rate concessions for a limited period of time. Following is a summary of loans, by class, that have been restructured:
			Three Months Ended March 31, 2015								Three Months Ended March 31, 2014
			Number			Pre-Modification			Post-		Number		Pre-Modification			Post-
			of			Outstanding			Modification		of		Outstanding			Modification
			Contracts			Recorded			Outstanding		Contracts		Recorded			Outstanding
						Investment			Recorded				Investment			Recorded
									Investment							Investment
	Commercial real estate			2		$	312		$	196		1	$	188		$	188
	Commercial and industrial			—			—			—		1		52			50
	Total commercial loans			2			312			196		2		240			238
	Direct installment			131			1,526			1,484		126		1,678			1,647
	Residential mortgages			14			581			631		9		281			280
	Indirect installment			5			16			16		7		17			16
	Consumer lines of credit			16			270			270		7		255			255
	Other			—			—			—		—		—			—
				168		$	2,705		$	2,597		151	$	2,471		$	2,436
Summary of Troubled Debt Restructurings by Class of Loans and Leases, Payment Default	Following is a summary of TDRs, by class of loans and leases, for which there was a payment default, excluding loans that were either charged-off or cured by period end. Default occurs when a loan is 90 days or more past due and is within 12 months of restructuring.
			Three Months Ended						Three Months Ended
			March 31, 2015 (1)						March 31, 2014 (1)
			Number of			Recorded			Number of		Recorded
			Contracts			Investment			Contracts		Investment
	Direct installment			37		$	105			18	$	171
	Residential mortgages			2			102			—		—
	Indirect installment			3			4			1		—
	Consumer lines of credit			1			92			—		—
	Other			—			—			—		—
				43		$	303			19	$	171
	-1	The recorded investment is as of period end.

Allowance_for_Credit_Losses_Ta

Allowance for Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Summary of Changes in Allowance for Credit Losses by Loan and Lease Class	Following is a summary of changes in the allowance for credit losses, by loan and lease class:
		Balance at		Charge-			Recoveries		Net			Provision			Balance at
		Beginning		Offs					Charge-			for credit			End of
		of Period							Offs			losses			Period
	Three Months Ended March 31, 2015
	Commercial real estate	$	37,588	$	(1,001	)	$	209	$	(792	)	$	1,996		$	38,792
	Commercial and industrial		32,645		(684	)		120		(564	)		722			32,803
	Commercial leases		2,398		(93	)		10		(83	)		261			2,576
	Total commercial loans and leases		72,631		(1,778	)		339		(1,439	)		2,979			74,171
	Direct installment		20,538		(2,433	)		269		(2,164	)		2,830			21,204
	Residential mortgages		8,024		(511	)		15		(496	)		943			8,471
	Indirect installment		7,504		(1,280	)		302		(978	)		1,131			7,657
	Consumer lines of credit		8,496		(410	)		40		(370	)		764			8,890
	Other		759		(335	)		11		(324	)		419			854
	Total allowance on originated loans and leases		117,952		(6,747	)		976		(5,771	)		9,066			121,247
	Purchased credit-impaired loans		660		(64	)		19		(45	)		6			621
	Other acquired loans		7,314		(77	)		330		253			(936	)		6,631
	Total allowance on acquired loans		7,974		(141	)		349		208			(930	)		7,252
	Total allowance	$	125,926	$	(6,888	)	$	1,325	$	(5,563	)	$	8,136		$	128,499
	Three Months Ended March 31, 2014
	Commercial real estate	$	32,548	$	(2,223	)	$	299	$	(1,924	)	$	7,910		$	38,534
	Commercial and industrial		32,603		(513	)		370		(143	)		(2,489	)		29,971
	Commercial leases		1,903		(87	)		29		(58	)		99			1,944
	Total commercial loans and leases		67,054		(2,823	)		698		(2,125	)		5,520			70,449
	Direct installment		17,824		(2,521	)		267		(2,254	)		1,060			16,630
	Residential mortgages		5,836		(132	)		4		(128	)		(401	)		5,307
	Indirect installment		6,409		(802	)		217		(585	)		676			6,500
	Consumer lines of credit		7,231		(323	)		55		(268	)		695			7,658
	Other		530		(262	)		5		(257	)		306			579
	Total allowance on originated loans and leases		104,884		(6,863	)		1,246		(5,617	)		7,856			107,123
	Purchased credit-impaired loans		1,000		(249	)		—		(249	)		(43	)		708
	Other acquired loans		4,900		9			286		295			(807	)		4,388
	Total allowance on acquired loans		5,900		(240	)		286		46			(850	)		5,096
	Total allowance	$	110,784	$	(7,103	)	$	1,532	$	(5,571	)	$	7,006		$	112,219
Summary of Individual and Collective Allowance for Credit Losses and Loan and Lease Balances by Class	Following is a summary of the individual and collective originated allowance for credit losses and corresponding loan and lease balances by class:
		Allowance					Loans and Leases Outstanding
		Individually		Collectively			Loans and		Individually			Collectively
		Evaluated for		Evaluated for			Leases		Evaluated for			Evaluated for
		Impairment		Impairment					Impairment			Impairment
	March 31, 2015
	Commercial real estate	$	735	$	38,057		$	3,082,385	$	12,865		$	3,069,520
	Commercial and industrial		1,446		31,357			2,281,075		5,711			2,275,364
	Commercial leases		—		2,576			180,207		—			180,207
	Total commercial loans and leases		2,181		71,990			5,543,667		18,576			5,525,091
	Direct installment		—		21,204			1,594,846		—			1,594,846
	Residential mortgages		—		8,471			877,437		—			877,437
	Indirect installment		—		7,657			903,780		—			903,780
	Consumer lines of credit		—		8,890			953,569		—			953,569
	Other		—		854			42,632		—			42,632
		$	2,181	$	119,066		$	9,915,931	$	18,576		$	9,897,355
	December 31, 2014
	Commercial real estate	$	399	$	37,189		$	3,031,810	$	13,952		$	3,017,858
	Commercial and industrial		780		31,865			2,197,793		5,837			2,191,956
	Commercial leases		—		2,398			177,824		—			177,824
	Total commercial loans and leases		1,179		71,452			5,407,427		19,789			5,387,638
	Direct installment		—		20,538			1,579,770		—			1,579,770
	Residential mortgages		—		8,024			817,586		—			817,586
	Indirect installment		—		7,504			873,645		—			873,645
	Consumer lines of credit		—		8,496			946,427		—			946,427
	Other		—		759			41,290		—			41,290
		$	1,179	$	116,773		$	9,666,145	$	19,789		$	9,646,356

Borrowings_Tables

Borrowings (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of Short-Term Borrowings	Following is a summary of short-term borrowings:
		March 31,		December 31,
		2015		2014
	Securities sold under repurchase agreements	$	757,279	$	882,696
	Federal Home Loan Bank advances		500,000		820,000
	Federal funds purchased		355,000		210,000
	Subordinated notes		128,221		128,962
		$	1,740,500	$	2,041,658
Summary of Long-Term Borrowings	Following is a summary of long-term borrowings:
		March 31,		December 31,
		2015		2014
	Federal Home Loan Bank advances	$	400,018	$	400,042
	Subordinated notes		83,197		83,155
	Junior subordinated debt		58,259		58,246
		$	541,474	$	541,443
Junior Subordinated Debt Trusts	The following table provides information relating to the Trusts as of March 31, 2015:
		Trust		Common		Junior		Stated		Interest
		Preferred		Securities		Subordinated		Maturity		Rate
		Securities				Debt		Date
	F.N.B. Statutory Trust II	$	21,500	$	665	$	22,165		6/15/36		1.92	%	Variable; LIBOR + 165 basis points (bps)
	Omega Financial Capital Trust I		36,000		1,114		36,094		10/18/34		2.44	%	Variable; LIBOR + 219 bps
		$	57,500	$	1,779	$	58,259

Derivative_And_Hedging_Activit1

Derivative And Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2015
Schedule of Notional Amounts and Gross Fair Values of Derivative Assets and Derivative Liabilities	The following table presents notional amounts and gross fair values of all derivative assets and derivative liabilities held by the Corporation:
		March 31, 2015								December 31, 2014
		Notional		Fair Value						Notional		Fair Value
		Amount		Asset			Liability			Amount		Asset		Liability
	Gross Derivatives
	Subject to master netting arrangements:
	Interest rate contracts – designated	$	200,000	$	3,937		$	669		$	200,000	$	2,109	$	2,330
	Interest rate swaps – not designated		1,020,957		6			53,718			972,002		140		43,655
	Equity contracts – not designated		1,210		39			—			1,210		47		—
	Total subject to master netting arrangements		1,222,167		3,982			54,387			1,173,212		2,296		45,985
	Not subject to master netting arrangements:
	Interest rate swaps – not designated		1,020,957		53,569			5			972,002		43,602		128
	Credit risk contracts – not designated		76,416		—			—			68,632		—		—
	Equity contracts – not designated		1,210		—			39			1,210		—		47
	Total not subject to master netting arrangements		1,098,583		53,569			44			1,041,844		43,602		175
		$	2,320,750	$	57,551		$	54,431		$	2,215,056	$	45,898	$	46,160
Derivative Assets
		Gross		Gross			Net Amount
		Amount		Amounts			Presented in
				Offset in			the Balance
				the Balance			Sheet
				Sheet
	March 31, 2015
	Derivative Assets
	Subject to master netting arrangements:
	Interest rate contracts
	Designated	$	3,937		—		$	3,937
	Not designated		6		—			6
	Equity contracts – not designated		39		—			39
	Not subject to master netting arrangements:
	Interest rate contracts – not designated		53,569		—			53,569
		$	57,551		—		$	57,551
	December 31, 2014
	Derivative Assets
	Subject to master netting arrangements:
	Interest rate contracts
	Designated	$	2,109		—		$	2,109
	Not designated		140		—			140
	Equity contracts – not designated		47		—			47
	Not subject to master netting arrangements:
	Interest rate contracts – not designated		43,602		—			43,602
		$	45,898		—		$	45,898
Derivative Liabilities
		Gross		Gross			Net Amount
		Amount		Amounts			Presented in
				Offset in			the Balance
				the Balance			Sheet
				Sheet
	March 31, 2015
	Derivative Liabilities
	Subject to master netting arrangements:
	Interest rate contracts
	Designated	$	669		—		$	669
	Not designated		53,718		—			53,718
	Not subject to master netting arrangements:
	Interest rate contracts – not designated		5		—			5
	Equity contracts – not designated		39		—			39
		$	54,431		—		$	54,431
	December 31, 2014
	Derivative Liabilities
	Subject to master netting arrangements:
	Interest rate contracts
	Designated	$	2,330		—		$	2,330
	Not designated		43,655		—			43,655
	Not subject to master netting arrangements:
	Interest rate contracts – not designated		128		—			128
	Equity contracts – not designated		47		—			47
		$	46,160		—		$	46,160
Effect of Corporation's Derivative Financial Instruments on Income Statement	The following table presents the effect of the Corporation’s derivative financial instruments on the income statement:
		Income		Three Months Ended
		Statement		March 31,
		Location		2015			2014
	Interest Rate Products		Other income	$	(107	)	$	(14	)
Collateral Held By Counterparty [Member]
Derivative Assets
				Amount Not Offset in the
				Balance Sheet
		Net Amount		Financial			Cash			Net
		Presented in		Instruments			Collateral			Amount
		the Balance
		Sheet
	March 31, 2015
	Derivative Assets
	Interest rate contracts:
	Designated	$	3,937	$	1,902		$	2,035			—
	Not designated		6		6			—			—
	Equity contracts – not designated		39		39			—			—
		$	3,982	$	1,947		$	2,035			—
	December 31, 2014
	Derivative Assets
	Interest rate contracts:
	Designated	$	2,109	$	810		$	1,299			—
	Not designated		140		138			2			—
	Equity contracts – not designated		47		47			—			—
		$	2,296	$	995		$	1,301			—
Derivative Liabilities
				Amount Not Offset in the
				Balance Sheet
		Net Amount		Financial			Cash			Net
		Presented in		Instruments			Collateral			Amount
		the Balance
		Sheet
	March 31, 2015
	Derivative Liabilities
	Interest rate contracts:
	Designated	$	669	$	669		$	—		$	—
	Not designated		53,718		30,626			21,346			1,746
		$	54,387	$	31,295		$	21,346		$	1,746
	December 31, 2014
	Derivative Liabilities
	Interest rate contracts:
	Designated	$	2,330	$	2,330		$	—		$	—
	Not designated		43,655		28,646			13,243			1,766
		$	45,985	$	30,976		$	13,243		$	1,766

Commitments_Credit_Risk_and_Co1

Commitments, Credit Risk and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Summary of Off-Balance Sheet Credit Risk Information	Following is a summary of off-balance sheet credit risk information:
		March 31,		December 31,
		2015		2014
	Commitments to extend credit	$	3,969,614	$	3,665,481
	Standby letters of credit		109,355		121,186

Stock_Incentive_Plans_Tables

Stock Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Information Concerning Restricted Stock Awards	The following table summarizes certain information concerning restricted stock awards:
		Three Months Ended March 31,
		2015					2014
		Awards			Weighted		Awards			Weighted
					Average					Average
					Grant					Grant
					Price					Price
	Unvested awards outstanding at beginning of period		1,354,093		$	11.86		1,729,033		$	10.23
	Net adjustment due to performance		(46,956	)		10.25		(19,002	)		8.48
	Vested		(458,450	)		10.6		(667,956	)		9.01
	Forfeited		(2,357	)		17.93		(430	)		10.69
	Dividend reinvestment		7,656			14.24		9,612			13.01
	Unvested awards outstanding at end of period		853,986			12.63		1,051,257			11.06
Components of Restricted Stock Awards	Compensation. The components of the restricted stock awards as of March 31, 2015 are as follows:
		Service-			Performance-		Total
		Based			Based
		Awards			Awards
	Unvested awards		397,593			456,393		853,986
	Unrecognized compensation expense	$	2,659		$	1,850	$	4,509
	Intrinsic value	$	5,224		$	5,997	$	11,221
	Weighted average remaining life (in years)		1.91			1.73		1.81
Summary of Information Concerning Stock Option Awards	The following table summarizes certain information concerning stock option awards:
		Three Months Ended March 31,
		2015					2014
		Shares			Weighted		Shares			Weighted
					Average					Average
					Exercise					Exercise
					Price					Price
	Options outstanding at beginning of period		568,834		$	8.86		533,524		$	11.5
	Assumed from acquisition		—			—		304,785			5.77
	Exercised		(60,094	)		5.04		(87,332	)		6.05
	Forfeited		(2,182	)		4.34		(48,172	)		25.79
	Options outstanding and exercisable at end of period		506,558			9.33		702,805			8.71

Retirement_Plans_Tables

Retirement Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Net Periodic Benefit Credit for Defined Benefit Plans	The net periodic benefit credit for the defined benefit plans includes the following components:
		Three Months Ended
		March 31,
		2015			2014
	Service cost	$	17		$	16
	Interest cost		1,477			1,596
	Expected return on plan assets		(2,491	)		(2,487	)
	Amortization:
	Unrecognized net transition asset		—			(5	)
	Unrecognized prior service cost		2			2
	Unrecognized loss		536			337
	Net periodic pension credit	$	(459	)	$	(541	)

Comprehensive_Income_Tables

Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Components of Comprehensive Income, Net of Related Tax	The components of comprehensive income, net of related tax, are as follows:
		Three Months Ended
		March 31,
		2015			2014
	Net income	$	40,343		$	34,524
	Other comprehensive income:
	Securities available for sale:
	Unrealized gains arising during the period, net of tax expense of $4,523 and $9,016		8,400			16,742
	Reclassification adjustment for losses (gains) included in net income, net of tax (benefit) expense of $(3) and $3,311		6			(6,150	)
	Derivative instruments:
	Unrealized gains arising during the period, net of tax expense of $1,504 and $1,402		2,793			2,603
	Reclassification adjustment for gains included in net income, net of tax expense of $283 and $285		(526	)		(529	)
	Pension and postretirement benefit obligations:
	Unrealized gains arising during the period, net of tax expense of $189 and $117		350			217
	Other comprehensive income		11,023			12,883
	Comprehensive income	$	51,366		$	47,407
Changes in AOCI, Net of Tax, by Component	The following table presents changes in AOCI, net of tax, by component:
		Unrealized			Unrealized			Unrecognized			Total
		Net Gains			Net Gains			Pension and
		(Losses) on			(Losses) on			Postretirement
		Securities			Derivative			Obligations
		Available			Instruments
		for Sale
	Three Months Ended March 31, 2015
	Balance at beginning of period	$	(440	)	$	(143	)	$	(45,420	)	$	(46,003	)
	Other comprehensive income before reclassifications		8,400			2,793			350			11,543
	Amounts reclassified from AOCI		6			(526	)		—			(520	)
	Net current period other comprehensive income		8,406			2,267			350			11,023
	Balance at end of period	$	7,966		$	2,124		$	(45,070	)	$	(34,980	)

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Common Share	The following table sets forth the computation of basic and diluted earnings per common share:
		Three Months Ended
		March 31,
		2015		2014
	Net income	$	40,343	$	34,524
	Less: Preferred stock dividends		2,010		2,322
	Net income available to common stockholders	$	38,333	$	32,202
	Basic weighted average common shares outstanding		174,152,283		162,186,395
	Net effect of dilutive stock options, warrants, restricted stock and convertible debt		1,673,693		1,780,851
	Diluted weighted average common shares outstanding		175,825,976		163,967,246
	Earnings per common share:
	Basic	$	0.22	$	0.2
	Diluted	$	0.22	$	0.2

Cash_Flow_Information_Tables

Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information	Following is a summary of supplemental cash flow information:
	Three Months Ended March 31	2015		2014
	Interest paid on deposits and other borrowings	$	11,626	$	10,576
	Income taxes paid		—		—
	Transfers of loans to other real estate owned		1,965		4,849
	Financing of other real estate owned sold		166		—

Business_Segments_Tables

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Financial Information for Segments of Corporation	The following tables provide financial information for these segments of the Corporation. The information provided under the caption “Parent and Other” represents operations not considered to be reportable segments and/or general operating expenses of the Corporation, and includes the parent company, other non-bank subsidiaries and eliminations and adjustments which are necessary for purposes of reconciliation to the consolidated amounts.
		Community		Wealth		Insurance			Consumer		Parent and			Consolidated
		Banking		Management					Finance		Other
	At or for the Three Months Ended March 31, 2015
	Interest income	$	122,118	$	—	$	23		$	9,593	$	1,635		$	133,369
	Interest expense		9,941		—		—			860		647			11,448
	Net interest income		112,177		—		23			8,733		988			121,921
	Provision for credit losses		6,327		—		—			1,574		235			8,136
	Non-interest income		27,301		8,387		3,593			676		(1,775	)		38,182
	Non-interest expense		77,079		6,493		4,170			4,808		(10	)		92,540
	Intangible amortization		1,947		68		100			—		—			2,115
	Income tax expense (benefit)		15,931		658		(226	)		1,149		(543	)		16,969
	Net income (loss)		38,194		1,168		(428	)		1,878		(469	)		40,343
	Total assets		16,100,851		21,125		18,464			182,662		(44,254	)		16,278,848
	Total intangibles		852,764		10,652		10,021			1,809		—			875,246
	At or for the Three Months Ended March 31, 2014
	Interest income	$	106,691	$	—	$	25		$	9,365	$	1,799		$	117,880
	Interest expense		8,248		—		—			846		961			10,055
	Net interest income		98,443		—		25			8,519		838			107,825
	Provision for credit losses		5,296		—		—			1,457		253			7,006
	Non-interest income		31,913		7,323		4,210			660		(2,036	)		42,070
	Non-interest expense		76,866		6,292		3,046			4,937		742			91,883
	Intangible amortization		2,110		72		101			—		—			2,283
	Income tax expense (benefit)		13,343		351		385			1,073		(953	)		14,199
	Net income (loss)		32,741		608		703			1,712		(1,240	)		34,524
	Total assets		14,299,543		19,542		19,954			182,018		(44,547	)		14,476,510
	Total intangibles		833,642		10,936		10,425			1,809		—			856,812

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Balances of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents the balances of assets and liabilities measured at fair value on a recurring basis:
		Level 1			Level 2			Level 3			Total
	March 31, 2015
	Assets Measured at Fair Value
	Available for sale debt securities:
	U.S. Treasury	$	—		$	29,937		$	—		$	29,937
	U.S. government-sponsored entities		—			390,660			—			390,660
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		—			505,561			—			505,561
	Agency collateralized mortgage obligations		—			572,017			—			572,017
	Non-agency collateralized mortgage obligations		—			10			1,354			1,364
	Commercial mortgage-backed securities		—			6,843			—			6,843
	States of the U.S. and political subdivisions		—			13,175			—			13,175
	Other debt securities		—			16,231			—			16,231
			—			1,534,434			1,354			1,535,788
	Available for sale equity securities:
	Financial services industry		91			645			435			1,171
	Insurance services industry		121			—			—			121
			212			645			435			1,292
			212			1,535,079			1,789			1,537,080
	Derivative financial instruments:
	Trading		—			53,614			—			53,614
	Not for trading		—			3,937			—			3,937
			—			57,551			—			57,551
		$	212		$	1,592,630		$	1,789		$	1,594,631
	Liabilities Measured at Fair Value
	Derivative financial instruments:
	Trading		—		$	53,762			—		$	53,762
	Not for trading		—			669			—			669
			—		$	54,431			—		$	54,431
		Level 1			Level 2			Level 3			Total
	December 31, 2014
	Assets Measured at Fair Value
	Available for sale debt securities:
	U.S. Treasury	$	—		$	29,682		$	—		$	29,682
	U.S. government-sponsored entities		—			337,133			—			337,133
	Residential mortgage-backed securities:
	Agency mortgage-backed securities		—			554,085			—			554,085
	Agency collateralized mortgage obligations		—			573,171			—			573,171
	Non-agency collateralized mortgage obligations		—			11			1,420			1,431
	Commercial mortgage-backed securities		—			7,880			—			7,880
	States of the U.S. and political subdivisions		—			13,158			—			13,158
	Other debt securities		—			16,178			—			16,178
			—			1,531,298			1,420			1,532,718
	Available for sale equity securities:
	Financial services industry		99			654			475			1,228
	Insurance services industry		119			—			—			119
			218			654			475			1,347
			218			1,531,952			1,895			1,534,065
	Derivative financial instruments:
	Trading		—			43,789			—			43,789
	Not for trading		—			2,109			—			2,109
			—			45,898			—			45,898
		$	218		$	1,577,850		$	1,895		$	1,579,963
	Liabilities Measured at Fair Value
	Derivative financial instruments:
	Trading		—		$	43,830			—		$	43,830
	Not for trading		—			2,330			—			2,330
			—		$	46,160			—		$	46,160
Additional Information about Assets Measured at Fair Value on Recurring Basis	The following table presents additional information about assets measured at fair value on a recurring basis and for which the Corporation has utilized Level 3 inputs to determine fair value:
		Pooled Trust			Equity			Residential			Total
		Preferred			Securities			Non-Agency
		Collateralized						Collateralized
		Debt						Mortgage
		Obligations						Obligations
	Three Months Ended March 31, 2015
	Balance at beginning of period		—		$	475		$	1,420		$	1,895
	Total gains (losses) – realized/unrealized:
	Included in earnings		—			—			—			—
	Included in other comprehensive income		—			(40	)		(12	)		(52	)
	Accretion included in earnings		—			—			1			1
	Purchases, issuances, sales and settlements:
	Purchases		—			—			—			—
	Issuances		—			—			—			—
	Sales/redemptions		—			—			—			—
	Settlements		—			—			(55	)		(55	)
	Transfers from Level 3		—			—			—			—
	Transfers into Level 3		—			—			—			—
	Balance at end of period		—		$	435		$	1,354		$	1,789
	Year Ended December 31, 2014
	Balance at beginning of period	$	31,595		$	410		$	1,744		$	33,749
	Total gains (losses) – realized/unrealized:
	Included in earnings		13,766			—			—			13,766
	Included in other comprehensive income		5,608			65			3			5,676
	Accretion included in earnings		657			—			5			662
	Purchases, issuances, sales and settlements:
	Purchases		—			—			—			—
	Issuances		—			—			—			—
	Sales/redemptions		(51,527	)		—			—			(51,527	)
	Settlements		(99	)		—			(332	)		(431	)
	Transfers from Level 3		—			—			—			—
	Transfers into Level 3		—			—			—			—
	Balance at end of period	$	—		$	475		$	1,420		$	1,895
Additional Information about Assets Measured at Fair Value on Non-Recurring Basis	measure these fair value adjustments were previously described. For assets measured at fair value on a non-recurring basis still held at the balance sheet date, the following table provides the hierarchy level and the fair value of the related assets or portfolios:
		Level 1			Level 2			Level 3			Total
	March 31, 2015
	Impaired loans		—		$	190		$	693		$	883
	Other real estate owned		—			977			1,433			2,410
	December 31, 2014
	Impaired loans		—			177			1,528			1,705
	Other real estate owned		—			5,695			2,365			8,060
Fair Values of Corporation's Financial Instruments	The fair values of the Corporation’s financial instruments are as follows:
								Fair Value Measurements
		Carrying			Fair Value			Level 1			Level 2			Level 3
		Amount
	March 31, 2015
	Financial Assets
	Cash and cash equivalents	$	234,246		$	234,246		$	234,246		$	—		$	—
	Securities available for sale		1,537,080			1,537,080			212			1,535,079			1,789
	Securities held to maturity		1,513,204			1,536,449			—			1,532,588			3,861
	Net loans and leases, including loans held for sale		11,280,221			11,119,711			—			—			11,119,711
	Derivative assets		57,551			57,551			—			57,551			—
	Accrued interest receivable		41,935			41,935			41,935			—			—
	Financial Liabilities
	Deposits		11,806,043			11,812,401			9,217,159			2,595,242			—
	Short-term borrowings		1,740,500			1,740,499			1,740,499			—			—
	Long-term borrowings		541,474			541,955			—			—			541,955
	Derivative liabilities		54,431			54,431			—			54,431			—
	Accrued interest payable		6,511			6,511			6,511			—			—
	December 31, 2014
	Financial Assets
	Cash and cash equivalents	$	287,393		$	287,393		$	287,393		$	—		$	—
	Securities available for sale		1,534,065			1,534,065			218			1,531,952			1,895
	Securities held to maturity		1,453,355			1,468,258			—			1,463,945			4,313
	Net loans and leases, including loans held for sale		11,127,292			10,956,544			—			—			10,956,544
	Derivative assets		45,898			45,898			—			45,898			—
	Accrued interest receivable		40,231			40,231			40,231			—			—
	Financial Liabilities
	Deposits		11,382,208			11,382,402			8,771,173			2,611,229			—
	Short-term borrowings		2,041,658			2,041,672			2,041,672			—			—
	Long-term borrowings		541,443			539,007			—			—			539,007
	Derivative liabilities		46,160			46,160			—			46,160			—
	Accrued interest payable		6,689			6,689			6,689			—			—

Business_Additional_Informatio

Business - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
	Office
	Location
	State
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states, Company operating financial services	6
Number of metropolitan areas, Company operating financial services	3
Number of consumer finance offices	73
Number of banking offices	287

Mergers_and_Acquisitions_Addit

Mergers and Acquisitions - Additional Information (Detail) (USD $)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 19, 2014	Feb. 15, 2014	Mar. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill recorded as a result of merger			$829,726	$832,213
OBA Financial Services, Inc. (OBA) [Member]
Business Acquisition [Line Items]
Assets acquired as a result of merger	390,128
Loans acquired as a result of merger	291,393
Deposits acquired as a result of merger	295,922
Value of acquisition	85,554
Common shares issued	7,170,037
Common shares acquired	4,025,895
Goodwill recorded as a result of merger	20,139
Core deposit intangibles recorded as result of the acquisition	4,304
BCSB Bancorp, Inc. (BCSB) [Member]
Business Acquisition [Line Items]
Assets acquired as a result of merger		596,122
Loans acquired as a result of merger		304,932
Deposits acquired as a result of merger		532,197
Value of acquisition		80,547
Common shares issued		6,730,597
Common shares acquired		3,235,961
Goodwill recorded as a result of merger		42,451
Core deposit intangibles recorded as result of the acquisition		$6,591

Securities_Schedule_of_Amortiz

Securities - Schedule of Amortized Cost and Fair Value of Securities Available for Sale (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	$1,524,825	$1,534,771
Securities Available For Sale, Gross Unrealized Gains	18,943	11,215
Securities Available For Sale, Gross Unrealized Losses	-6,688	-11,921
Securities Available For Sale, Fair Value	1,537,080	1,534,065
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	29,637	29,604
Securities Available For Sale, Gross Unrealized Gains	300	78
Securities Available For Sale, Fair Value	29,937	29,682
U.S. Government-Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	388,363	338,330
Securities Available For Sale, Gross Unrealized Gains	2,818	742
Securities Available For Sale, Gross Unrealized Losses	-521	-1,939
Securities Available For Sale, Fair Value	390,660	337,133
Agency Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	494,497	546,572
Securities Available For Sale, Gross Unrealized Gains	11,064	7,548
Securities Available For Sale, Gross Unrealized Losses		-35
Securities Available For Sale, Fair Value	505,561	554,085
Securities Available For Sale, Fair Value	505,561
Agency Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	573,738	580,601
Securities Available For Sale, Gross Unrealized Gains	3,646	1,617
Securities Available For Sale, Gross Unrealized Losses	-5,367	-9,047
Securities Available For Sale, Fair Value	572,017	573,171
Securities Available For Sale, Fair Value	572,017
Non-Agency Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	1,359	1,414
Securities Available For Sale, Gross Unrealized Gains	5	17
Securities Available For Sale, Fair Value	1,364	1,431
Securities Available For Sale, Fair Value	1,364
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	6,844	7,891
Securities Available For Sale, Gross Unrealized Losses	-1	-11
Securities Available For Sale, Fair Value	6,843	7,880
Securities Available For Sale, Fair Value	6,843
States of the U.S. and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	12,713	12,713
Securities Available For Sale, Gross Unrealized Gains	476	477
Securities Available For Sale, Gross Unrealized Losses	-14	-32
Securities Available For Sale, Fair Value	13,175	13,158
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	16,643	16,615
Securities Available For Sale, Gross Unrealized Gains	373	420
Securities Available For Sale, Gross Unrealized Losses	-785	-857
Securities Available For Sale, Fair Value	16,231	16,178
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	1,523,794	1,533,740
Securities Available For Sale, Gross Unrealized Gains	18,682	10,899
Securities Available For Sale, Gross Unrealized Losses	-6,688	-11,921
Securities Available For Sale, Fair Value	1,535,788	1,532,718
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available For Sale, Amortized Cost	1,031	1,031
Securities Available For Sale, Gross Unrealized Gains	261	316
Securities Available For Sale, Gross Unrealized Losses	0	0
Securities Available For Sale, Fair Value	1,292	1,347
Securities Available For Sale, Fair Value	$1,292

Securities_Schedule_of_Amortiz1

Securities - Schedule of Amortized Cost and Fair Value of Securities Held to Maturity (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	$1,513,204	$1,453,355
Securities Held To Maturity, Gross Unrealized Gains	28,454	23,145
Securities Held To Maturity, Gross Unrealized Losses	-5,209	-8,242
Securities held to maturity, fair value	1,536,449	1,468,258
U.S. Treasury [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	500	502
Securities Held To Maturity, Gross Unrealized Gains	182	168
Securities held to maturity, fair value	682	670
U.S. Government-Sponsored Entities [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	146,578	101,602
Securities Held To Maturity, Gross Unrealized Gains	1,731	885
Securities Held To Maturity, Gross Unrealized Losses	-149	-524
Securities held to maturity, fair value	148,160	101,963
Agency Mortgage-Backed Securities [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	674,101	677,169
Securities Held To Maturity, Gross Unrealized Gains	19,130	16,712
Securities Held To Maturity, Gross Unrealized Losses	-20	-346
Securities held to maturity, fair value	693,211	693,535
Agency Collateralized Mortgage Obligations [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	505,859	501,965
Securities Held To Maturity, Gross Unrealized Gains	3,633	1,858
Securities Held To Maturity, Gross Unrealized Losses	-4,884	-7,329
Securities held to maturity, fair value	504,608	496,494
Non-Agency Collateralized Mortgage Obligations [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	3,840	4,285
Securities Held To Maturity, Gross Unrealized Gains	21	28
Securities held to maturity, fair value	3,861	4,313
Commercial Mortgage-Backed Securities [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	17,484	17,560
Securities Held To Maturity, Gross Unrealized Gains	385	179
Securities held to maturity, fair value	17,869	17,739
States of the U.S. and Political Subdivisions [Member]
Investment Securities Held To Maturity [Line Items]
Securities Held To Maturity, Amortized Cost	164,842	150,272
Securities Held To Maturity, Gross Unrealized Gains	3,372	3,315
Securities Held To Maturity, Gross Unrealized Losses	-156	-43
Securities held to maturity, fair value	$168,058	$153,544

Securities_Gross_Gains_and_Gro

Securities - Gross Gains and Gross Losses Realized on Sales of Securities (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Gross gains		$18,009
Gross losses	-9	-8,548
Total	($9)	$9,461

Securities_Additional_Informat

Securities - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	Security	Securities
Schedule Of Securities [Line Items]
Number of pooled issue securities		23
Net proceeds from sale of securities	$33,228	$85,877
Net securities (losses) gains	-9	9,461
Securities pledged to secure public deposits, trust deposits and for other purposes, carrying value	1,315,565		1,036,380
Securities pledged as collateral for short-term borrowings, carrying value	807,261		892,647
Number of single-issuer securities	4
Estimated fair value of single-issue trust preferred securities	6,890
Amortized cost of single-issue trust preferred securities	6,105
Impairment losses on securities	0	0
Municipal bond portfolio, value	178,017
Municipal Debt Securities [Member] | Combined A Rating [Member] | Minimum [Member]
Schedule Of Securities [Line Items]
Percentage of portfolio	99.00%
Municipal Debt Securities [Member] | General Obligation Bonds [Member]
Schedule Of Securities [Line Items]
Percentage of portfolio	99.50%
Municipal Debt Securities [Member] | Pennsylvania, Ohio and Maryland [Member]
Schedule Of Securities [Line Items]
Percentage of portfolio	89.90%
Municipal Debt Securities [Member] | Capital Support Agreement [Member]
Schedule Of Securities [Line Items]
Percentage of portfolio	88.00%
Municipal Debt Securities [Member] | Weighted Average [Member]
Schedule Of Securities [Line Items]
Carrying amount per bond	1,203
Pooled TPS [Member]
Schedule Of Securities [Line Items]
Net proceeds from sale of securities		51,540
Net securities (losses) gains		13,766
Other Securities [Member]
Schedule Of Securities [Line Items]
Net securities (losses) gains		($4,305)

Securities_Amortized_Cost_and_

Securities - Amortized Cost and Fair Value of Securities, by Contractual Maturities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule Of Securities [Line Items]
Available for Sale, Due in one year or less, Amortized Cost	$4,985
Available for Sale, Due from one to five years, Amortized Cost	423,890
Available for Sale, Due from five to ten years, Amortized Cost	11,591
Available for Sale, Due after ten years, Amortized Cost	6,890
Available for Sale, with contractual maturities, Amortized Cost	447,356
Total securities available for sale, Amortized Cost	1,524,825	1,534,771
Available for Sale, Due in one year or less, Fair Value	5,069
Available for Sale, Due from one to five years, Fair Value	426,811
Available for Sale, Due from five to ten years, Fair Value	12,018
Available for Sale, Due after ten years, Fair Value	6,105
Available for Sale, with contractual maturities, Fair Value	450,003
Total available for sale Securities, Fair Value	1,537,080	1,534,065
Held to Maturity, Due in one year or less, Amortized Cost	1,282
Held to Maturity, Due from one to five years, Amortized Cost	138,269
Held to Maturity, Due from five to ten years, Amortized Cost	72,457
Held to Maturity, Due after ten years, Amortized Cost	99,912
Securities Held To Maturity, with contractual maturities, Amortized Cost	311,920
Held to Maturity, with contractual maturities, Amortized Cost	1,513,204	1,453,355
Held to Maturity, Due in one year or less, Fair Value	1,285
Held to Maturity, Due from one to five years, Fair Value	139,139
Held to Maturity, Due from five to ten years, Fair Value	74,672
Held to Maturity, Due after ten years, Fair Value	101,804
Securities Held To Maturity, with contractual maturities, Fair Value	316,900
Held to Maturity, with contractual maturities, Fair Value	1,536,449	1,468,258
Agency Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Total securities available for sale, Amortized Cost	494,497	546,572
Total available for sale Securities, Fair Value	505,561
Held to Maturity, with contractual maturities, Amortized Cost	674,101	677,169
Held to Maturity, with contractual maturities, Fair Value	693,211	693,535
Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Total securities available for sale, Amortized Cost	573,738	580,601
Total available for sale Securities, Fair Value	572,017
Held to Maturity, with contractual maturities, Amortized Cost	505,859	501,965
Held to Maturity, with contractual maturities, Fair Value	504,608	496,494
Non-Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Total securities available for sale, Amortized Cost	1,359	1,414
Total available for sale Securities, Fair Value	1,364
Held to Maturity, with contractual maturities, Amortized Cost	3,840	4,285
Held to Maturity, with contractual maturities, Fair Value	3,861	4,313
Commercial Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Total securities available for sale, Amortized Cost	6,844	7,891
Total available for sale Securities, Fair Value	6,843
Held to Maturity, with contractual maturities, Amortized Cost	17,484	17,560
Held to Maturity, with contractual maturities, Fair Value	17,869	17,739
Equity Securities [Member]
Schedule Of Securities [Line Items]
Total securities available for sale, Amortized Cost	1,031	1,031
Total available for sale Securities, Fair Value	$1,292

Securities_Summaries_of_Fair_V

Securities - Summaries of Fair Values and Unrealized Losses of Securities, Segregated by Length of Impairment (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified	Security	Security
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	8	19
Number of available for sale securities, Greater than 1 year	27	28
Number of available for sale securities	35	47
Securities Available For Sale, Less than 12 Months, Fair Value	$128,698	$309,919
Securities Available For Sale, Less than 12 Months, Unrealized Losses	-342	-1,559
Securities Available For Sale, 12 Months or More, Fair Value	305,018	332,215
Securities Available For Sale, 12 Months or More, Unrealized Losses	-6,346	-10,362
Securities Available For Sale, Fair Value, Total	433,716	642,134
Securities Available For Sale, Unrealized Losses, Total	-6,688	-11,921
Number of held to maturity securities	29	36
Securities Held To Maturity, Less than 12 Months, Fair Value	98,314	131,586
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	-588	-675
Securities Held To Maturity, Greater than 12 Months, Fair Value	201,581	269,653
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	-4,621	-7,567
Securities Held To Maturity, Fair Value, Total	299,895	401,239
Securities Held To Maturity, Unrealized Losses, Total	-5,209	-8,242
Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	13	12
Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	16	24
U.S. Government-Sponsored Entities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	3	7
Number of available for sale securities, Greater than 1 year	5	7
Number of available for sale securities	8	14
Securities Available For Sale, Less than 12 Months, Fair Value	59,857	89,986
Securities Available For Sale, Less than 12 Months, Unrealized Losses	-142	-275
Securities Available For Sale, 12 Months or More, Fair Value	55,612	99,326
Securities Available For Sale, 12 Months or More, Unrealized Losses	-379	-1,664
Securities Available For Sale, Fair Value, Total	115,469	189,312
Securities Available For Sale, Unrealized Losses, Total	-521	-1,939
Number of held to maturity securities	2	4
Securities Held To Maturity, Less than 12 Months, Fair Value	14,970	24,989
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	-30	-40
Securities Held To Maturity, Greater than 12 Months, Fair Value	14,881	29,516
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	-119	-484
Securities Held To Maturity, Fair Value, Total	29,851	54,505
Securities Held To Maturity, Unrealized Losses, Total	-149	-524
U.S. Government-Sponsored Entities [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1	2
U.S. Government-Sponsored Entities [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1	2
Agency Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year		2
Number of available for sale securities		2
Securities Available For Sale, Less than 12 Months, Fair Value		45,145
Securities Available For Sale, Less than 12 Months, Unrealized Losses		-35
Securities Available For Sale, Fair Value, Total		45,145
Securities Available For Sale, Unrealized Losses, Total		-35
Number of held to maturity securities	1	5
Securities Held To Maturity, Less than 12 Months, Fair Value		1,099
Securities Held To Maturity, Less than 12 Months, Unrealized Losses		-1
Securities Held To Maturity, Greater than 12 Months, Fair Value	1,234	45,042
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	-20	-345
Securities Held To Maturity, Fair Value, Total	1,234	46,141
Securities Held To Maturity, Unrealized Losses, Total	-20	-346
Agency Mortgage-Backed Securities [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities		1
Agency Mortgage-Backed Securities [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	1	4
Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	4	9
Number of available for sale securities, Greater than 1 year	17	16
Number of available for sale securities	21	25
Securities Available For Sale, Less than 12 Months, Fair Value	61,998	166,908
Securities Available For Sale, Less than 12 Months, Unrealized Losses	-199	-1,238
Securities Available For Sale, 12 Months or More, Fair Value	242,124	225,700
Securities Available For Sale, 12 Months or More, Unrealized Losses	-5,168	-7,809
Securities Available For Sale, Fair Value, Total	304,122	392,608
Securities Available For Sale, Unrealized Losses, Total	-5,367	-9,047
Number of held to maturity securities	18	22
Securities Held To Maturity, Less than 12 Months, Fair Value	69,926	104,071
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	-402	-630
Securities Held To Maturity, Greater than 12 Months, Fair Value	185,466	189,642
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses	-4,482	-6,699
Securities Held To Maturity, Fair Value, Total	255,392	293,713
Securities Held To Maturity, Unrealized Losses, Total	-4,884	-7,329
Agency Collateralized Mortgage Obligations [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	4	8
Agency Collateralized Mortgage Obligations [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	14	14
Commercial Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Less than 1 year	1	1
Number of available for sale securities	1	1
Securities Available For Sale, Less than 12 Months, Fair Value	6,843	7,880
Securities Available For Sale, Less than 12 Months, Unrealized Losses	-1	-11
Securities Available For Sale, Fair Value, Total	6,843	7,880
Securities Available For Sale, Unrealized Losses, Total	-1	-11
States of the U.S. and Political Subdivisions [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Greater than 1 year	1	1
Number of available for sale securities	1	1
Securities Available For Sale, 12 Months or More, Fair Value	1,177	1,159
Securities Available For Sale, 12 Months or More, Unrealized Losses	-14	-32
Securities Available For Sale, Fair Value, Total	1,177	1,159
Securities Available For Sale, Unrealized Losses, Total	-14	-32
Number of held to maturity securities	8	5
Securities Held To Maturity, Less than 12 Months, Fair Value	13,418	1,427
Securities Held To Maturity, Less than 12 Months, Unrealized Losses	-156	-4
Securities Held To Maturity, Greater than 12 Months, Fair Value		5,453
Securities Held To Maturity, Greater than 12 Months, Unrealized Losses		-39
Securities Held To Maturity, Fair Value, Total	13,418	6,880
Securities Held To Maturity, Unrealized Losses, Total	-156	-43
States of the U.S. and Political Subdivisions [Member] | Less than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities	8	1
States of the U.S. and Political Subdivisions [Member] | Greater than 12 Months [Member]
Schedule Of Securities [Line Items]
Number of held to maturity securities		4
Other Securities [Member]
Schedule Of Securities [Line Items]
Number of available for sale securities, Greater than 1 year	4	4
Number of available for sale securities	4	4
Securities Available For Sale, 12 Months or More, Fair Value	6,105	6,030
Securities Available For Sale, 12 Months or More, Unrealized Losses	-785	-857
Securities Available For Sale, Fair Value, Total	6,105	6,030
Securities Available For Sale, Unrealized Losses, Total	($785)	($857)

Securities_Summary_of_Cumulati

Securities - Summary of Cumulative Credit-Related OTTI Charges (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Beginning balance	$27	$17,182
Loss where impairment was not previously recognized	0	0
Additional loss where impairment was previously recognized	0	0
Reduction due to credit impaired securities sold		-17,155
Ending balance	27	27
Collateralized Debt Obligations [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Beginning balance		17,155
Loss where impairment was not previously recognized	0	0
Additional loss where impairment was previously recognized	0	0
Reduction due to credit impaired securities sold		-17,155
Equity Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Beginning balance	27	27
Loss where impairment was not previously recognized	0	0
Additional loss where impairment was previously recognized	0	0
Ending balance	$27	$27

Federal_Home_Loan_Bank_Stock_A

Federal Home Loan Bank Stock - Additional Information (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Statement of Financial Position [Abstract]
Federal Home Loan Bank stock	$42,000	$54,751

Loans_and_Leases_Summary_of_Lo

Loans and Leases - Summary of Loans and Leases, Net of Unearned Income (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	$11,404,099	$11,247,038
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,817,189	3,815,708
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	2,397,731	2,318,015
Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	180,207	177,824
Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	6,395,127	6,311,547
Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,653,621	1,644,621
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,299,097	1,263,053
Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	905,204	875,551
Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,108,418	1,110,976
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	42,632	41,290
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	9,915,931	9,666,145
Originated Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	3,082,385	3,031,810
Originated Loans [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	2,281,075	2,197,793
Originated Loans [Member] | Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	180,207	177,824
Originated Loans [Member] | Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	5,543,667	5,407,427
Originated Loans [Member] | Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,594,846	1,579,770
Originated Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	877,437	817,586
Originated Loans [Member] | Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	903,780	873,645
Originated Loans [Member] | Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	953,569	946,427
Originated Loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	42,632	41,290
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,488,168	1,580,893
Acquired Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	734,804	783,898
Acquired Loans [Member] | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	116,656	120,222
Acquired Loans [Member] | Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	851,460	904,120
Acquired Loans [Member] | Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	58,775	64,851
Acquired Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	421,660	445,467
Acquired Loans [Member] | Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	1,424	1,906
Acquired Loans [Member] | Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned income	$154,849	$164,549

Loans_and_Leases_Additional_In

Loans and Leases - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial construction loans	$227,179		$296,156
Carrying amount	11,404,099		11,247,038
Sustained period of delinquency for impairment evaluation	90 days	90 days
Minimum corporation reserves for commercial loan	500
Minimum amount to allocate specific valuation allowance	500
Allowance for loan losses	7,252		7,974
Restructured loans returned to performing status	3,975
Valuation for impairment of loans with pooled reserves	500		500
Pooled reserves for all other classes of loans	4,146		3,448
Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	174,239		180,588
Carrying amount	1,108,418		1,110,976
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	3,817,189		3,815,708
Allowance for loan losses	3,327		3,286
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	2,397,731		2,318,015
Allowance for loan losses	712		1,484
Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	1,653,621		1,644,621
Allowance for loan losses	1,477		1,847
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	1,299,097		1,263,053
Allowance for loan losses	1,193		858
Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	905,204		875,551
Allowance for loan losses	229		232
Consumer Lines Of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	314		267
Loans and Leases Receivable Net of Deferred Income [Member] | Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of portfolio	1.50%		1.60%
Loans and Leases Receivable Net of Deferred Income [Member] | Commercial Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of portfolio	2.00%		2.60%
Commercial Real Estate [Member] | Owner-Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of portfolio	40.80%		41.60%
Commercial Real Estate [Member] | Non-Owner-Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of portfolio	59.20%		58.40%
Specific reserves for commercial TDRs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserves in allowance for loan losses, TDRs	646		371
Pooled reserves for commercial TDRs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reserves in allowance for loan losses, TDRs	1,203		1,215
Purchased Credit-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	7,100		9,556
Purchased Credit-Impaired Loans [Member] | Acquired Loans Receivable [Member] | Credit Concentration Risk [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of portfolio	1.00%
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for default non-accrual status of trade accounts receivable	90 days
Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for default non-accrual status of trade accounts receivable	120 days
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for default non-accrual status of trade accounts receivable	180 days
Carrying value of OREO through foreclosure	3,541
Mortgage loans on real estate, foreclosure	$14,186

Loans_and_Leases_Summary_of_Ou

Loans and Leases - Summary of Outstanding Principal Balance and Carrying Amount of Acquired Loans (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount	$11,404,099	$11,247,038
Accounted for under ASC 310-30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	1,513,616	1,597,558
Carrying amount	1,259,995	1,344,171
Accounted for under ASC 310-20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	232,524	242,488
Carrying amount	220,921	228,748
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	1,746,140	1,840,046
Carrying amount	$1,480,916	$1,572,919

Loans_and_Leases_Summary_of_Ch

Loans and Leases - Summary of Change in Accretable Yield of Acquired Loans (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period [Abstract]
Balance at beginning of period	$331,899	$305,646
Reduction due to unexpected early payoffs	-11,909	-12,694
Reclass from non-accretable difference	7,676	768
Disposals/transfers	-118	-944
Accretion	-16,264	-15,913
Balance at end of period	$311,284	$276,863

Loans_and_Leases_Summary_of_No

Loans and Leases - Summary of Non-Performing Assets (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings	$42,855	$41,152
Non-Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	45,029	45,113
Troubled debt restructurings	22,022	23,439
Total non-performing loans	67,051	68,552
Other real estate owned (OREO)	40,796	41,466
Total non-performing assets	$107,847	$110,018
Non-performing loans as a percent of total loans and leases	0.59%	0.61%
Non-performing loans + OREO as a percent of total loans and leases + OREO	0.94%	0.97%
Non-performing assets as a percent of total assets	0.66%	0.68%

Loans_and_Leases_Age_Analysis_

Loans and Leases - Age Analysis of Past Due Loans, by Class (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$11,404,099	$11,247,038
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	3,817,189	3,815,708
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	2,397,731	2,318,015
Commercial Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	180,207	177,824
Total Commercial Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	6,395,127	6,311,547
Direct Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,653,621	1,644,621
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,299,097	1,263,053
Indirect Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	905,204	875,551
Consumer Lines of Credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,108,418	1,110,976
Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	42,632	41,290
Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	34,042	41,275
> 90 Days Past Due and Still Accruing	6,543	9,248
Non-Accrual	45,029	45,113
Total Past Due	85,614	95,636
Current	9,830,317	9,570,509
Total Loans	9,915,931	9,666,145
Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	6,655	9,601
> 90 Days Past Due and Still Accruing	130	313
Non-Accrual	23,653	24,132
Total Past Due	30,438	34,046
Current	3,051,947	2,997,764
Total Loans	3,082,385	3,031,810
Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	2,939	2,446
> 90 Days Past Due and Still Accruing	3	3
Non-Accrual	8,846	8,310
Total Past Due	11,788	10,759
Current	2,269,287	2,187,034
Total Loans	2,281,075	2,197,793
Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,097	961
> 90 Days Past Due and Still Accruing		43
Non-Accrual	732	722
Total Past Due	1,829	1,726
Current	178,378	176,098
Total Loans	180,207	177,824
Originated Loans and Leases [Member] | Total Commercial Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	10,691	13,008
> 90 Days Past Due and Still Accruing	133	359
Non-Accrual	33,231	33,164
Total Past Due	44,055	46,531
Current	5,499,612	5,360,896
Total Loans	5,543,667	5,407,427
Originated Loans and Leases [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	8,748	9,333
> 90 Days Past Due and Still Accruing	3,575	3,617
Non-Accrual	6,464	7,117
Total Past Due	18,787	20,067
Current	1,576,059	1,559,703
Total Loans	1,594,846	1,579,770
Originated Loans and Leases [Member] | Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	7,040	8,709
> 90 Days Past Due and Still Accruing	1,731	3,891
Non-Accrual	3,625	2,964
Total Past Due	12,396	15,564
Current	865,041	802,022
Total Loans	877,437	817,586
Originated Loans and Leases [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	5,015	7,804
> 90 Days Past Due and Still Accruing	409	684
Non-Accrual	1,111	1,149
Total Past Due	6,535	9,637
Current	897,245	864,008
Total Loans	903,780	873,645
Originated Loans and Leases [Member] | Consumer Lines of Credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	2,501	2,408
> 90 Days Past Due and Still Accruing	656	562
Non-Accrual	598	719
Total Past Due	3,755	3,689
Current	949,814	942,738
Total Loans	953,569	946,427
Originated Loans and Leases [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	47	13
> 90 Days Past Due and Still Accruing	39	135
Total Past Due	86	148
Current	42,546	41,142
Total Loans	42,632	41,290
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	19,854	24,678
> 90 Days Past Due and Still Accruing	35,906	38,024
Total Past Due	55,760	62,702
Current	1,523,538	1,612,959
Discount	-91,130	-94,768
Total Loans	1,488,168	1,580,893
Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	8,813	12,076
> 90 Days Past Due and Still Accruing	12,445	12,368
Total Past Due	21,258	24,444
Current	753,073	799,991
Discount	-39,527	-40,537
Total Loans	734,804	783,898
Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,023	687
> 90 Days Past Due and Still Accruing	1,651	1,968
Total Past Due	2,674	2,655
Current	122,604	127,535
Discount	-8,622	-9,968
Total Loans	116,656	120,222
Acquired Loans [Member] | Total Commercial Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	9,836	12,763
> 90 Days Past Due and Still Accruing	14,096	14,336
Total Past Due	23,932	27,099
Current	875,677	927,526
Discount	-48,149	-50,505
Total Loans	851,460	904,120
Acquired Loans [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,199	2,670
> 90 Days Past Due and Still Accruing	1,112	1,443
Total Past Due	2,311	4,113
Current	55,476	59,532
Discount	988	1,206
Total Loans	58,775	64,851
Acquired Loans [Member] | Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	7,695	8,159
> 90 Days Past Due and Still Accruing	18,535	19,936
Total Past Due	26,230	28,095
Current	434,061	456,810
Discount	-38,631	-39,438
Total Loans	421,660	445,467
Acquired Loans [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	9	38
> 90 Days Past Due and Still Accruing	17	30
Total Past Due	26	68
Current	1,648	2,179
Discount	-250	-341
Total Loans	1,424	1,906
Acquired Loans [Member] | Consumer Lines of Credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,115	1,048
> 90 Days Past Due and Still Accruing	2,146	2,279
Total Past Due	3,261	3,327
Current	156,676	166,912
Discount	-5,088	-5,690
Total Loans	$154,849	$164,549

Loans_and_Leases_Summary_of_Co

Loans and Leases - Summary of Commercial Loans and Leases by Credit Quality (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	$5,543,667	$5,407,427
Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	3,082,385	3,031,810
Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,281,075	2,197,793
Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	180,207	177,824
Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	851,460	904,120
Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	734,804	783,898
Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	116,656	120,222
Pass [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	5,327,699	5,151,400
Pass [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,960,542	2,890,830
Pass [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,190,066	2,085,893
Pass [Member] | Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	177,091	174,677
Pass [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	682,436	714,122
Pass [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	579,462	610,260
Pass [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	102,974	103,862
Special Mention [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	108,630	132,248
Special Mention [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	52,926	58,630
Special Mention [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	53,482	71,420
Special Mention [Member] | Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,222	2,198
Special Mention [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	67,303	77,397
Special Mention [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	64,892	73,891
Special Mention [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,411	3,506
Substandard [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	105,157	122,584
Substandard [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	68,182	81,951
Substandard [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	36,081	39,684
Substandard [Member] | Originated Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	894	949
Substandard [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	101,721	112,601
Substandard [Member] | Acquired Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	90,450	99,747
Substandard [Member] | Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	11,271	12,854
Doubtful [Member] | Originated Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	2,181	1,195
Doubtful [Member] | Originated Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	735	399
Doubtful [Member] | Originated Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial loans and leases	$1,446	$796

Loans_and_Leases_Summary_of_Co1

Loans and Leases - Summary of Consumer Loans by Payment Status (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Credit Quality [Line Items]
Total Loans	$11,404,099	$11,247,038
Non-Performing [Member]
Credit Quality [Line Items]
Non-Performing Loans	67,051	68,552
Direct Installment [Member]
Credit Quality [Line Items]
Total Loans	1,653,621	1,644,621
Direct Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	1,581,078	1,565,090
Direct Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Non-Performing Loans	13,768	14,680
Residential Mortgages [Member]
Credit Quality [Line Items]
Total Loans	1,299,097	1,263,053
Residential Mortgages [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	862,965	802,522
Residential Mortgages [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Non-Performing Loans	14,472	15,064
Indirect Installment [Member]
Credit Quality [Line Items]
Total Loans	905,204	875,551
Indirect Installment [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	902,515	872,340
Indirect Installment [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Non-Performing Loans	1,265	1,305
Consumer Lines of Credit [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	951,980	944,631
Consumer Lines of Credit [Member] | Non-Performing [Member]
Credit Quality [Line Items]
Non-Performing Loans	1,589	1,796
Other [Member]
Credit Quality [Line Items]
Total Loans	42,632	41,290
Other [Member] | Performing [Member]
Credit Quality [Line Items]
Performing Loans	42,632	41,290
Originated Loans [Member]
Credit Quality [Line Items]
Total Loans	9,915,931	9,666,145
Originated Loans [Member] | Direct Installment [Member]
Credit Quality [Line Items]
Total Loans	1,594,846	1,579,770
Originated Loans [Member] | Residential Mortgages [Member]
Credit Quality [Line Items]
Total Loans	877,437	817,586
Originated Loans [Member] | Indirect Installment [Member]
Credit Quality [Line Items]
Total Loans	903,780	873,645
Originated Loans [Member] | Consumer Lines of Credit [Member]
Credit Quality [Line Items]
Total Loans	953,569	946,427
Originated Loans [Member] | Other [Member]
Credit Quality [Line Items]
Total Loans	$42,632	$41,290

Loans_and_Leases_Summary_of_Im

Loans and Leases - Summary of Impaired Loans, by Class (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	$79,186	$81,765
Recorded Investment With No Specific Reserve	64,979	66,619
Recorded Investment With Specific Reserve	2,940	2,831
Total Recorded Investment	67,919	69,450
Specific Reserve	2,181	1,179
Average Recorded Investment	69,663	75,367
Commercial Real Estate [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	34,483	34,583
Recorded Investment With No Specific Reserve	25,015	25,443
Recorded Investment With Specific Reserve	1,012	883
Total Recorded Investment	26,027	26,326
Specific Reserve	735	399
Average Recorded Investment	26,176	30,807
Commercial and Industrial [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	11,251	11,412
Recorded Investment With No Specific Reserve	8,138	7,609
Recorded Investment With Specific Reserve	1,928	1,948
Total Recorded Investment	10,066	9,557
Specific Reserve	1,446	780
Average Recorded Investment	9,811	9,510
Commercial Leases [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	732	722
Recorded Investment With No Specific Reserve	732	722
Total Recorded Investment	732	722
Average Recorded Investment	727	686
Total Commercial Loans and Leases [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	46,466	46,717
Recorded Investment With No Specific Reserve	33,885	33,774
Recorded Investment With Specific Reserve	2,940	2,831
Total Recorded Investment	36,825	36,605
Specific Reserve	2,181	1,179
Average Recorded Investment	36,714	41,003
Direct Installment [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	13,977	14,987
Recorded Investment With No Specific Reserve	13,768	14,680
Total Recorded Investment	13,768	14,680
Average Recorded Investment	14,343	14,248
Residential Mortgages [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	15,718	16,791
Recorded Investment With No Specific Reserve	14,472	15,064
Total Recorded Investment	14,472	15,064
Average Recorded Investment	15,547	16,924
Indirect Installment [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	1,425	1,467
Recorded Investment With No Specific Reserve	1,265	1,305
Total Recorded Investment	1,265	1,305
Average Recorded Investment	1,363	1,399
Consumer Lines of Credit [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	1,600	1,803
Recorded Investment With No Specific Reserve	1,589	1,796
Total Recorded Investment	1,589	1,796
Average Recorded Investment	$1,696	$1,793

Loans_and_Leases_Summary_of_Pa

Loans and Leases - Summary of Payment Status of Total TDRs (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	$42,855	$41,152
Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	12,793	9,441
Non-Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	22,022	23,439
Non-Accrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings ("TDRs")	$8,040	$8,272

Loans_and_Leases_Summary_of_Tr

Loans and Leases - Summary of Troubled Debt Restructurings by Class of Loans (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	Contract	Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	168	151
Pre-Modification Outstanding Recorded Investment	$2,705	$2,471
Post-Modification Outstanding Recorded Investment	2,597	2,436
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	1
Pre-Modification Outstanding Recorded Investment	312	188
Post-Modification Outstanding Recorded Investment	196	188
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts		1
Pre-Modification Outstanding Recorded Investment		52
Post-Modification Outstanding Recorded Investment		50
Total Commercial Loans and Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	2
Pre-Modification Outstanding Recorded Investment	312	240
Post-Modification Outstanding Recorded Investment	196	238
Direct Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	131	126
Pre-Modification Outstanding Recorded Investment	1,526	1,678
Post-Modification Outstanding Recorded Investment	1,484	1,647
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	14	9
Pre-Modification Outstanding Recorded Investment	581	281
Post-Modification Outstanding Recorded Investment	631	280
Indirect Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	5	7
Pre-Modification Outstanding Recorded Investment	16	17
Post-Modification Outstanding Recorded Investment	16	16
Consumer Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	16	7
Pre-Modification Outstanding Recorded Investment	270	255
Post-Modification Outstanding Recorded Investment	$270	$255

Loans_and_Leases_Summary_of_Tr1

Loans and Leases - Summary of Troubled Debt Restructurings by Class of Loans and Leases, Payment Default (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
	Contract		Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	43		19
Recorded Investment	$303	[1]	$171	[1]
Direct Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	37		18
Recorded Investment	105	[1]	171	[1]
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2
Recorded Investment	102	[1]
Indirect Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3		1
Recorded Investment	4	[1]
Consumer Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1
Recorded Investment	$92	[1]
[1]	The recorded investment is as of period end.

Allowance_for_Credit_Losses_Ad

Allowance for Credit Losses - Additional Information (Detail) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Receivables [Abstract]
Minimum corporation reserves for commercial loan	$500

Allowance_for_Credit_Losses_Su

Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses by Loan and Lease Class (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	$125,926	$110,784
Charge- Offs	-6,888	-7,103
Recoveries	1,325	1,532
Net Charge- Offs	-5,563	-5,571
Provision for credit losses	8,136	7,006
Balance at End of Period	128,499	112,219
Originated Loans [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	117,952	104,884
Charge- Offs	-6,747	-6,863
Recoveries	976	1,246
Net Charge- Offs	-5,771	-5,617
Provision for credit losses	9,066	7,856
Balance at End of Period	121,247	107,123
Acquired Loans [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	7,974	5,900
Charge- Offs	-141	-240
Recoveries	349	286
Net Charge- Offs	208	46
Provision for credit losses	-930	-850
Balance at End of Period	7,252	5,096
Commercial Real Estate [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	37,588	32,548
Charge- Offs	-1,001	-2,223
Recoveries	209	299
Net Charge- Offs	-792	-1,924
Provision for credit losses	1,996	7,910
Balance at End of Period	38,792	38,534
Commercial and Industrial [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	32,645	32,603
Charge- Offs	-684	-513
Recoveries	120	370
Net Charge- Offs	-564	-143
Provision for credit losses	722	-2,489
Balance at End of Period	32,803	29,971
Commercial Leases [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	2,398	1,903
Charge- Offs	-93	-87
Recoveries	10	29
Net Charge- Offs	-83	-58
Provision for credit losses	261	99
Balance at End of Period	2,576	1,944
Total Commercial Loans and Leases [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	72,631	67,054
Charge- Offs	-1,778	-2,823
Recoveries	339	698
Net Charge- Offs	-1,439	-2,125
Provision for credit losses	2,979	5,520
Balance at End of Period	74,171	70,449
Direct Installment [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	20,538	17,824
Charge- Offs	-2,433	-2,521
Recoveries	269	267
Net Charge- Offs	-2,164	-2,254
Provision for credit losses	2,830	1,060
Balance at End of Period	21,204	16,630
Residential Mortgages [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	8,024	5,836
Charge- Offs	-511	-132
Recoveries	15	4
Net Charge- Offs	-496	-128
Provision for credit losses	943	-401
Balance at End of Period	8,471	5,307
Indirect Installment [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	7,504	6,409
Charge- Offs	-1,280	-802
Recoveries	302	217
Net Charge- Offs	-978	-585
Provision for credit losses	1,131	676
Balance at End of Period	7,657	6,500
Consumer Lines of Credit [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	8,496	7,231
Charge- Offs	-410	-323
Recoveries	40	55
Net Charge- Offs	-370	-268
Provision for credit losses	764	695
Balance at End of Period	8,890	7,658
Other [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	759	530
Charge- Offs	-335	-262
Recoveries	11	5
Net Charge- Offs	-324	-257
Provision for credit losses	419	306
Balance at End of Period	854	579
Purchased Credit-Impaired Loans [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	660	1,000
Charge- Offs	-64	-249
Recoveries	19
Net Charge- Offs	-45	-249
Provision for credit losses	6	-43
Balance at End of Period	621	708
Other Acquired Loans [Member]
Schedule Of Allowance For Loan Losses [Line Items]
Balance at Beginning of Period	7,314	4,900
Charge- Offs	-77	9
Recoveries	330	286
Net Charge- Offs	253	295
Provision for credit losses	-936	-807
Balance at End of Period	$6,631	$4,388

Allowance_for_Credit_Losses_Su1

Allowance for Credit Losses - Summary of Individual and Collective Allowance for Credit Losses and Loan and Lease Balances by Class (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Valuation Allowance [Line Items]
Allowance, Individually Evaluated for Impairment	$2,181	$1,179
Allowance, Collectively Evaluated for Impairment	119,066	116,773
Loans and Leases	11,404,099	11,247,038
Loans Outstanding, Individually Evaluated for Impairment	18,576	19,789
Loans Outstanding, Collectively Evaluated for Impairment	9,897,355	9,646,356
Commercial Real Estate [Member]
Valuation Allowance [Line Items]
Allowance, Individually Evaluated for Impairment	735	399
Allowance, Collectively Evaluated for Impairment	38,057	37,189
Loans and Leases	3,817,189	3,815,708
Loans Outstanding, Individually Evaluated for Impairment	12,865	13,952
Loans Outstanding, Collectively Evaluated for Impairment	3,069,520	3,017,858
Commercial and Industrial [Member]
Valuation Allowance [Line Items]
Allowance, Individually Evaluated for Impairment	1,446	780
Allowance, Collectively Evaluated for Impairment	31,357	31,865
Loans and Leases	2,397,731	2,318,015
Loans Outstanding, Individually Evaluated for Impairment	5,711	5,837
Loans Outstanding, Collectively Evaluated for Impairment	2,275,364	2,191,956
Commercial Leases [Member]
Valuation Allowance [Line Items]
Allowance, Collectively Evaluated for Impairment	2,576	2,398
Loans and Leases	180,207	177,824
Loans Outstanding, Collectively Evaluated for Impairment	180,207	177,824
Total Commercial Loans and Leases [Member]
Valuation Allowance [Line Items]
Allowance, Individually Evaluated for Impairment	2,181	1,179
Allowance, Collectively Evaluated for Impairment	71,990	71,452
Loans and Leases	6,395,127	6,311,547
Loans Outstanding, Individually Evaluated for Impairment	18,576	19,789
Loans Outstanding, Collectively Evaluated for Impairment	5,525,091	5,387,638
Direct Installment [Member]
Valuation Allowance [Line Items]
Allowance, Collectively Evaluated for Impairment	21,204	20,538
Loans and Leases	1,653,621	1,644,621
Loans Outstanding, Collectively Evaluated for Impairment	1,594,846	1,579,770
Residential Mortgages [Member]
Valuation Allowance [Line Items]
Allowance, Collectively Evaluated for Impairment	8,471	8,024
Loans and Leases	1,299,097	1,263,053
Loans Outstanding, Collectively Evaluated for Impairment	877,437	817,586
Indirect Installment [Member]
Valuation Allowance [Line Items]
Allowance, Collectively Evaluated for Impairment	7,657	7,504
Loans and Leases	905,204	875,551
Loans Outstanding, Collectively Evaluated for Impairment	903,780	873,645
Consumer Lines of Credit [Member]
Valuation Allowance [Line Items]
Allowance, Collectively Evaluated for Impairment	8,890	8,496
Loans and Leases	1,108,418	1,110,976
Loans Outstanding, Collectively Evaluated for Impairment	953,569	946,427
Other [Member]
Valuation Allowance [Line Items]
Allowance, Collectively Evaluated for Impairment	854	759
Loans and Leases	42,632	41,290
Loans Outstanding, Collectively Evaluated for Impairment	42,632	41,290
Originated Loans [Member]
Valuation Allowance [Line Items]
Loans and Leases	9,915,931	9,666,145
Originated Loans [Member] | Commercial Real Estate [Member]
Valuation Allowance [Line Items]
Loans and Leases	3,082,385	3,031,810
Originated Loans [Member] | Commercial and Industrial [Member]
Valuation Allowance [Line Items]
Loans and Leases	2,281,075	2,197,793
Originated Loans [Member] | Commercial Leases [Member]
Valuation Allowance [Line Items]
Loans and Leases	180,207	177,824
Originated Loans [Member] | Total Commercial Loans and Leases [Member]
Valuation Allowance [Line Items]
Loans and Leases	5,543,667	5,407,427
Originated Loans [Member] | Direct Installment [Member]
Valuation Allowance [Line Items]
Loans and Leases	1,594,846	1,579,770
Originated Loans [Member] | Residential Mortgages [Member]
Valuation Allowance [Line Items]
Loans and Leases	877,437	817,586
Originated Loans [Member] | Indirect Installment [Member]
Valuation Allowance [Line Items]
Loans and Leases	903,780	873,645
Originated Loans [Member] | Consumer Lines of Credit [Member]
Valuation Allowance [Line Items]
Loans and Leases	953,569	946,427
Originated Loans [Member] | Other [Member]
Valuation Allowance [Line Items]
Loans and Leases	$42,632	$41,290

Borrowings_Summary_of_ShortTer

Borrowings - Summary of Short-Term Borrowings (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]
Securities sold under repurchase agreements	$757,279	$882,696
Federal Home Loan Bank advances	500,000	820,000
Federal funds purchased	355,000	210,000
Subordinated notes	128,221	128,962
Short-term borrowings	$1,740,500	$2,041,658

Borrowings_Summary_of_LongTerm

Borrowings - Summary of Long-Term Borrowings (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]
Federal Home Loan Bank advances	$400,018	$400,042
Subordinated notes	83,197	83,155
Junior subordinated debt	58,259	58,246
Long-term debt	$541,474	$541,443

Borrowings_Additional_Informat

Borrowings - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Credit available with FHLB	$4,213,966
Credit with FHLB used	900,018
Federal Home Loan Bank advances are scheduled to mature periodically through the year	2021
Effective interest rates, minimum	0.76%	0.76%
Effective interest rates, maximum	4.19%	4.19%
Number of unconsolidated subsidiary trusts	2
Percent of the common equity of each Trust owned by the Corporation	100.00%
TPS Outstanding amount	58,259	58,246
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Percentage of TPS moving from tier 1 capital to tier 2 capital for 2015	25.00%
TPS Outstanding amount	$57,500
Percentage of TPS moving from tier 1 capital to tier 2 capital for 2016	75.00%

Borrowings_Junior_Subordinated

Borrowings - Junior Subordinated Debt Trusts (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Subordinated Borrowing [Line Items]
Junior subordinated debt	$58,259	$58,246
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	57,500
Common Stock Subject to Mandatory Redemption [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1,779
F.N.B. Statutory Trust II [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	22,165
Stated Maturity Date	15-Jun-36
Interest Rate	1.92%
Description of variable rate	Variable; LIBOR + 165 basis points (bps)
Basis points	1.65%
F.N.B. Statutory Trust II [Member] | Trust Preferred Securities Subject to Mandatory Redemption [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	21,500
F.N.B. Statutory Trust II [Member] | Common Stock Subject to Mandatory Redemption [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	665
Omega Financial Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	36,094
Stated Maturity Date	18-Oct-34
Interest Rate	2.44%
Description of variable rate	Variable; LIBOR + 219 bps
Basis points	2.19%
Omega Financial Capital Trust I [Member] | Trust Preferred Securities Subject to Mandatory Redemption [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	36,000
Omega Financial Capital Trust I [Member] | Common Stock Subject to Mandatory Redemption [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$1,114

Recovered_Sheet1

Derivative and Hedging Activities - Schedule of Notional Amounts and Gross Fair Values of Derivative Assets and Derivative Liabilities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Notional amount	$2,320,750	$2,215,056
Fair value,asset	57,551	45,898
Liability	54,431	46,160
Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional amount	200,000	200,000
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,020,957	972,002
Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,222,167	1,173,212
Fair value,asset	3,982	2,296
Liability	54,387	45,985
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional amount	200,000	200,000
Fair value,asset	3,937	2,109
Liability	669	2,330
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,020,957	972,002
Fair value,asset	6	140
Liability	53,718	43,655
Subject to Master Netting Arrangement [Member] | Credit Risk Contract [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,210	1,210
Fair value,asset	39	47
Subject to Master Netting Arrangement [Member] | Equity Contracts [Member]
Derivatives, Fair Value [Line Items]
Fair value,asset	39	47
Not Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,098,583	1,041,844
Fair value,asset	53,569	43,602
Liability	44	175
Not Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,020,957	972,002
Fair value,asset	53,569	43,602
Liability	5	128
Not Subject to Master Netting Arrangement [Member] | Credit Risk Contract [Member]
Derivatives, Fair Value [Line Items]
Notional amount	76,416	68,632
Not Subject to Master Netting Arrangement [Member] | Equity Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,210	1,210
Liability	$39	$47

Recovered_Sheet2

Derivative and Hedging Activities - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Derivative [Line Items]
Notional amount	$2,320,750		$2,215,056
Derivative assets	57,551		45,898
Derivative liabilities	54,431		46,160
Interest income	121,921	107,825
Amounts reclassified from accumulated other comprehensive Income	-520
Additional amount in excess of posted collateral required in case of breached agreements	2,071		1,862
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	200,000		200,000
Period to reclassification of cash flow hedge gain loss	12 months
Maximum length of time hedged in interest rate cash flow hedge	9 years
Derivative gains to be reclassified within twelve months	2,929
Derivative gains to be reclassified within twelve months, net of tax	1,904
Derivative gain or loses excluded from assessment of hedge effectiveness	0
Hedge ineffectiveness	0	0
Gains or losses from cash flow hedge derivatives reclassified to earnings	0	0
Interest Rate Contracts [Member] | Amount Reclassified from Other Comprehensive Income [Member]
Derivative [Line Items]
Interest income	810
Amounts reclassified from accumulated other comprehensive Income	526
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount	1,020,957		972,002
Credit Risk Contract Sold [Member]
Derivative [Line Items]
Notional amount	50,061
Risk participation agreements, minimum term	2 years
Risk participation agreements, maximum term	9 years
Maximum exposure under credit risk agreement assuming customer default	70		21
Trading Assets [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative assets	53,575		43,742
Not for Trading Assets [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative assets	3,937		2,109
Trading Liabilities [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative liabilities	53,723		43,783
Not for Trading Liabilities [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative liabilities	$669		$2,330

Derivative_and_Hedging_Activit2

Derivative and Hedging Activities - Offsetting of Derivative Assets (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Gross Amount	$57,551	$45,898
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	57,551	45,898
Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	3,982	2,296
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	3,937	2,109
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	3,937	2,109
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	6	140
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	6	140
Subject to Master Netting Arrangement [Member] | Equity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	39	47
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	39	47
Not Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	53,569	43,602
Not Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	53,569	43,602
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	$53,569	$43,602

Derivative_and_Hedging_Activit3

Derivative and Hedging Activities - Offsetting of Derivative Liabilities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Gross Amount	$54,431	$46,160
Gross Amounts Offset in the Balance Sheet, Derivative Liabilities	0	0
Net Amount Presented in the Balance Sheet	54,431	46,160
Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	54,387	45,985
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	669	2,330
Gross Amounts Offset in the Balance Sheet, Derivative Liabilities	0	0
Net Amount Presented in the Balance Sheet	669	2,330
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	53,718	43,655
Gross Amounts Offset in the Balance Sheet, Derivative Liabilities	0	0
Net Amount Presented in the Balance Sheet	53,718	43,655
Not Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	44	175
Not Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	5	128
Gross Amounts Offset in the Balance Sheet, Derivative Liabilities	0	0
Net Amount Presented in the Balance Sheet	5	128
Not Subject to Master Netting Arrangement [Member] | Equity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	39	47
Gross Amounts Offset in the Balance Sheet, Derivative Liabilities	0	0
Net Amount Presented in the Balance Sheet	$39	$47

Derivative_and_Hedging_Activit4

Derivative and Hedging Activities - Derivative Assets (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	$57,551	$45,898
Subject to Master Netting Arrangement [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	3,982	2,296
Gross Amounts Not Offset in the Balance Sheet Financial Instruments, Derivative Assets	1,947	995
Gross Amounts Not Offset in the Balance Sheet Cash Collateral Received, Derivative Assets	2,035	1,301
Net Amount, Derivative Assets	0	0
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	3,937	2,109
Gross Amounts Not Offset in the Balance Sheet Financial Instruments, Derivative Assets	1,902	810
Gross Amounts Not Offset in the Balance Sheet Cash Collateral Received, Derivative Assets	2,035	1,299
Net Amount, Derivative Assets	0	0
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	6	140
Gross Amounts Not Offset in the Balance Sheet Financial Instruments, Derivative Assets	6	138
Gross Amounts Not Offset in the Balance Sheet Cash Collateral Received, Derivative Assets		2
Net Amount, Derivative Assets	0	0
Subject to Master Netting Arrangement [Member] | Equity Contracts [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	39	47
Gross Amounts Not Offset in the Balance Sheet Financial Instruments, Derivative Assets	39	47
Net Amount, Derivative Assets	$0	$0

Derivative_and_Hedging_Activit5

Derivative and Hedging Activities - Derivative Liabilities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	$54,431	$46,160
Subject to Master Netting Arrangement [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	54,387	45,985
Gross Amount Not Offset in the Balance Sheet Financial Instruments, Derivative Liabilities	31,295	30,976
Gross Amount Not Offset in the Balance Sheet Cash Collateral Pledged, Derivative Liabilities	21,346	13,243
Net Amount, Derivative Liabilities	1,746	1,766
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	669	2,330
Gross Amount Not Offset in the Balance Sheet Financial Instruments, Derivative Liabilities	699	2,330
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	53,718	43,655
Gross Amount Not Offset in the Balance Sheet Financial Instruments, Derivative Liabilities	30,626	28,646
Gross Amount Not Offset in the Balance Sheet Cash Collateral Pledged, Derivative Liabilities	21,346	13,243
Net Amount, Derivative Liabilities	$1,746	$1,766

Derivative_and_Hedging_Activit6

Derivative and Hedging Activities - Effect of Corporation's Derivative Financial Instruments on Income Statement (Detail) (Interest Rate Contracts [Member], Other Income [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest Rate Contracts [Member] | Other Income [Member]
Derivative [Line Items]
Interest Rate Products	($107)	($14)

Commitments_Credit_Risk_and_Co2

Commitments, Credit Risk and Contingencies - Summary of Off-Balance Sheet Credit Risk Information (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Extended credit and standby letters of credit	$3,969,614	$3,665,481
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Extended credit and standby letters of credit	$109,355	$121,186

Commitments_Credit_Risk_and_Co3

Commitments, Credit Risk and Contingencies - Additional Information (Detail)	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Percentage of Commitments to extend credit dependent upon the financial condition of the customers	68.20%

Stock_Incentive_Plans_Addition

Stock Incentive Plans - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jun. 16, 2009	Apr. 06, 2013	Jan. 01, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards issued	0	0
Common stock shares available under incentive compensation plans	2,122,522
Unrecognized compensation cost related to unvested restricted stock awards	$4,509
Stock options exercised	60,094	87,332
Intrinsic value of outstanding and exercisable stock options	1,890
Common shares available for purchase under warrants			651,042
Parkvale Financial Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant issued	819,640
Annapolis Bancorp, Inc. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant issued, exercise price	$3.32
Warrant issued	342,564
Warrants converted to purchase common stock	367,916
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense related to restricted stock awards	340	532
Tax benefit related to restricted stock awards	119	186
Total fair value of awards vested	5,740	8,631
Unrecognized compensation cost related to unvested restricted stock awards	4,509
Amount subject to accelerated vesting under Incentive Compensation Plan	20
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised	60,094	59,217
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares available for purchase under warrants	1,302,083
Warrant Expires In 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant issued, exercise price	$11.52
Warrant Expires In 2019 [Member] | Annapolis Bancorp, Inc. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant issued, exercise price				$3.57
Service-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards issued, years	3 years
Unrecognized compensation cost related to unvested restricted stock awards	2,659
Performance-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards issued, years	3 years
Unrecognized compensation cost related to unvested restricted stock awards	$1,850
Warrant Expires in 2018 [Member] | Parkvale Financial Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant issued, exercise price					$5.81
Market Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock percentage of number of units issued	100.00%

Stock_Incentive_Plans_Summary_

Stock Incentive Plans - Summary of Information Concerning Restricted Stock Awards (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Awards, Unvested awards outstanding at beginning of period	1,354,093	1,729,033
Awards, Net adjustment due to performance	-46,956	-19,002
Awards,Vested	-458,450	-667,956
Awards,Forfeited	-2,357	-430
Awards,Dividend reinvestment	7,656	9,612
Awards,Unvested awards outstanding at end of period	853,986	1,051,257
Weighted Average Grant Price, Unvested awards outstanding at beginning of period	$11.86	$10.23
Weighted Average Grant Price, Net adjustment due to performance	$10.25	$8.48
Weighted Average Grant Price,Vested	$10.60	$9.01
Weighted Average Grant Price,Forfeited	$17.93	$10.69
Weighted Average Grant Price, Dividend reinvestment	$14.24	$13.01
Weighted Average Grant Price, Unvested awards outstanding at end of period	$12.63	$11.06

Stock_Incentive_Plans_Componen

Stock Incentive Plans - Components of Restricted Stock Awards (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested awards	853,986	1,354,093	1,051,257	1,729,033
Unrecognized compensation expense	$4,509
Intrinsic value	11,221
Weighted average remaining life (in years)	1 year 9 months 22 days
Service-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested awards	397,593
Unrecognized compensation expense	2,659
Intrinsic value	5,224
Weighted average remaining life (in years)	1 year 10 months 28 days
Performance-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested awards	456,393
Unrecognized compensation expense	1,850
Intrinsic value	$5,997
Weighted average remaining life (in years)	1 year 8 months 23 days

Stock_Incentive_Plans_Summary_1

Stock Incentive Plans - Summary of Information Concerning Stock Option Awards (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares, Options outstanding at beginning of period	568,834	533,524
Shares, Assumed from acquisition		304,785
Shares, Exercised	-60,094	-87,332
Shares, Forfeited	-2,182	-48,172
Shares, Options outstanding and exercisable at end of period	506,558	702,805
Weighted Average Exercise Price, Options outstanding at beginning of period	$8.86	$11.50
Weighted Average Exercise Price , Assumed from acquisition		$5.77
Weighted Average Price per Share, Exercised	$5.04	$6.05
Weighted Average Exercise Price , Forfeited	$4.34	$25.79
Weighted Average Exercise Price , Options outstanding and exercisable at end of period	$9.33	$8.71

Retirement_Plans_Additional_In

Retirement Plans - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2008
	RetirementPlans
Disclosure Retirement Plans [Abstract]
Number of supplemental non-qualified retirement plans sponsored by the Corporation	2
Consecutive calendar years used to calculate BRP benefits				5 years
Term of employment for consideration of BRP				10 years
Annuity equivalent of contribution to defined contribution plan deducted from monthly benefit of basic retirement plan	3.00%
Percent of employer match	100.00%		100.00%
Employee contribution percentage	6.00%		4.00%
Additional automatic contribution increase, percentage			3.00%
Additional discretionary contribution, performance goals, percentage	3.00%		2.00%
Contribution expense of the Corporation	$2,167	$2,570

Retirement_Plans_Net_Periodic_

Retirement Plans - Net Periodic Benefit Credit for Defined Benefit Plans (Detail) (Defined Benefit Plans [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$17	$16
Interest cost	1,477	1,596
Expected return on plan assets	-2,491	-2,487
Amortization:
Unrecognized net transition asset		-5
Unrecognized prior service cost	2	2
Unrecognized loss	536	337
Net periodic pension credit	($459)	($541)

Comprehensive_Income_Component

Comprehensive Income - Components of Comprehensive Income, Net of Related Tax (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Components Of Comprehensive Income [Abstract]
Net income	$40,343	$34,524
Securities available for sale, Unrealized gains arising during the period, net of tax expense of $4,523 and $9,016	8,400	16,742
Securities available for sale, Reclassification adjustment for losses (gains) included in net income, net of tax (benefit) expense of $(3) and $ 3,311	6	-6,150
Unrealized gains on derivative instruments arising during the period, net of tax expense of $1,504 and $1,402	2,793	2,603
Reclassification adjustment on derivative instruments for gains included in net income, net of tax expense of $283 and $285	-526	-529
Unrealized gains on pension and postretirement benefit obligations arising during the period, net of tax expense of $189 and $117	350	217
Other comprehensive income	11,023	12,883
Comprehensive income	$51,366	$47,407

Comprehensive_Income_Component1

Comprehensive Income - Components of Comprehensive Income, Net of Related Tax (Parenthetical) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Components Of Comprehensive Income [Abstract]
Securities available for sale, Unrealized gains arising during the period, tax expense	$4,523	$9,016
Securities available for sale, Reclassification adjustment for losses (gains) included in net income, tax (benefit) expense	-3	3,311
Unrealized gains on derivative instruments arising during the period, tax expense	1,504	1,402
Reclassification adjustment on derivative instruments for gains included in net income, tax expense	283	285
Unrealized gains on pension and postretirement benefit obligations arising during the period, tax expense	$189	$117

Comprehensive_Income_Changes_i

Comprehensive Income - Changes in AOCI, Net of Tax, by Component (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	($46,003)
Other comprehensive income before reclassifications	11,543
Amounts reclassified from AOCI	-520
Net current period other comprehensive income	11,023	12,883
Accumulated other comprehensive income (loss), balance at end of period	-34,980
Unrealized Net Gains (Losses) on Securities Available for Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	-440
Other comprehensive income before reclassifications	8,400
Amounts reclassified from AOCI	6
Net current period other comprehensive income	8,406
Accumulated other comprehensive income (loss), balance at end of period	7,966
Unrealized Net Gains (Losses) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	-143
Other comprehensive income before reclassifications	2,793
Amounts reclassified from AOCI	-526
Net current period other comprehensive income	2,267
Accumulated other comprehensive income (loss), balance at end of period	2,124
Unrecognized Pension and Postretirement Obligations [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), balance at beginning of period	-45,420
Other comprehensive income before reclassifications	350
Net current period other comprehensive income	350
Accumulated other comprehensive income (loss), balance at end of period	($45,070)

Earnings_Per_Common_Share_Comp

Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income	$40,343	$34,524
Less: Preferred stock dividends	2,010	2,322
Net income available to common stockholders	$38,333	$32,202
Basic weighted average common shares outstanding	174,152,283	162,186,395
Net effect of dilutive stock options, warrants, restricted stock and convertible debt	1,673,693	1,780,851
Diluted weighted average common shares outstanding	175,825,976	163,967,246
Basic	$0.22	$0.20
Diluted	$0.22	$0.20

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Common stock excluded from computation of diluted earnings per share	24,272	51,641

Cash_Flow_Information_Summary_

Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Cash Flows [Abstract]
Interest paid on deposits and other borrowings	$11,626	$10,576
Income taxes paid	0	0
Transfers of loans to other real estate owned	1,965	4,849
Financing of other real estate owned sold	$166

Business_Segments_Additional_I

Business Segments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
	Segment
Segment Reporting [Abstract]
Number of reportable segments	4

Business_Segments_Financial_In

Business Segments - Financial Information for Segments of Corporation (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Interest income	$133,369	$117,880
Interest expense	11,448	10,055
Net interest income	121,921	107,825
Provision for credit losses	8,136	7,006
Non-interest income	38,182	42,070
Non-interest expense	92,540	91,883
Intangible amortization	2,115	2,283
Income tax expense (benefit)	16,969	14,199
Net income (loss)	40,343	34,524
Total assets	16,278,848	14,476,510	16,127,090
Total intangibles	875,246	856,812
Operating Segments [Member] | Community Banking [Member]
Segment Reporting Information [Line Items]
Interest income	122,118	106,691
Interest expense	9,941	8,248
Net interest income	112,177	98,443
Provision for credit losses	6,327	5,296
Non-interest income	27,301	31,913
Non-interest expense	77,079	76,866
Intangible amortization	1,947	2,110
Income tax expense (benefit)	15,931	13,343
Net income (loss)	38,194	32,741
Total assets	16,100,851	14,299,543
Total intangibles	852,764	833,642
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting Information [Line Items]
Non-interest income	8,387	7,323
Non-interest expense	6,493	6,292
Intangible amortization	68	72
Income tax expense (benefit)	658	351
Net income (loss)	1,168	608
Total assets	21,125	19,542
Total intangibles	10,652	10,936
Operating Segments [Member] | Insurance [Member]
Segment Reporting Information [Line Items]
Interest income	23	25
Net interest income	23	25
Non-interest income	3,593	4,210
Non-interest expense	4,170	3,046
Intangible amortization	100	101
Income tax expense (benefit)	-226	385
Net income (loss)	-428	703
Total assets	18,464	19,954
Total intangibles	10,021	10,425
Operating Segments [Member] | Consumer Finance [Member]
Segment Reporting Information [Line Items]
Interest income	9,593	9,365
Interest expense	860	846
Net interest income	8,733	8,519
Provision for credit losses	1,574	1,457
Non-interest income	676	660
Non-interest expense	4,808	4,937
Income tax expense (benefit)	1,149	1,073
Net income (loss)	1,878	1,712
Total assets	182,662	182,018
Total intangibles	1,809	1,809
Parent and Other [Member]
Segment Reporting Information [Line Items]
Interest income	1,635	1,799
Interest expense	647	961
Net interest income	988	838
Provision for credit losses	235	253
Non-interest income	-1,775	-2,036
Non-interest expense	-10	742
Income tax expense (benefit)	-543	-953
Net income (loss)	-469	-1,240
Total assets	($44,254)	($44,547)

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
	Securities	Securities
Fair Value Measurements Disclosure [Line Items]
Percentage of securities using market-based information	99.90%
Percentage of securities using model-based techniques	0.10%
Minimum corporation reserves for commercial loan	$500
Number of securities transferred between hierarchy levels	0	0
Impaired loans, carrying amount	67,919	69,450
Allocated allowance for loan losses	2,181
Fair value of allocated allowance	883
Estimated costs to sell	124
Provision for fair value measurements included in allowance for loan losses	1,002
Carrying amount of OREO	2,501
Written down of OREO	2,140
Fair value of OREO	2,410
Estimated cost to sell OREO	270
Loss from OREO included in earnings	361
Short-term borrowings approximate fair value for amounts that mature, days, less than	90 days
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Impaired loans, carrying amount	2,940
Allocated allowance for loan losses	883	1,705
Fair value of OREO	2,410	8,060
Assets Still Held [Member]
Fair Value Measurements Disclosure [Line Items]
Change in unrealized gains or losses included in earnings relating to assets still held	$0		$0

Fair_Value_Measurements_Balanc

Fair Value Measurements - Balances of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (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]
Assets measured at fair value, Available for sale securities	$1,537,080	$1,534,065
Derivative financial instruments	57,551	45,898
Derivative financial instruments	54,431	46,160
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	29,937	29,682
U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	390,660	337,133
Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	572,017	573,171
Assets measured at fair value, Available for sale securities	572,017
Non-Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	1,364	1,431
Assets measured at fair value, Available for sale securities	1,364
Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	6,843	7,880
Assets measured at fair value, Available for sale securities	6,843
States of the U.S. and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	13,175	13,158
Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	16,231	16,178
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale securities	212	218
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale securities	1,535,079	1,531,952
Derivative financial instruments	57,551	45,898
Derivative financial instruments	54,431	46,160
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale securities	1,789	1,895
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	1,535,788	1,532,718
Assets measured at fair value, Available for sale equity securities	1,292	1,347
Assets measured at fair value, Available for sale securities	1,537,080	1,534,065
Derivative financial instruments	57,551	45,898
Assets measured at fair value, Total	1,594,631	1,579,963
Liabilities measured at fair value, Total	54,431	46,160
Fair Value, Measurements, Recurring [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	29,937	29,682
Fair Value, Measurements, Recurring [Member] | U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	390,660	337,133
Fair Value, Measurements, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	572,017	573,171
Fair Value, Measurements, Recurring [Member] | Non-Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	1,364	1,431
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	6,843	7,880
Fair Value, Measurements, Recurring [Member] | States of the U.S. and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	13,175	13,158
Fair Value, Measurements, Recurring [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	16,231	16,178
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	505,561	554,085
Fair Value, Measurements, Recurring [Member] | Financial Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	1,171	1,228
Fair Value, Measurements, Recurring [Member] | Insurance Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	121	119
Fair Value, Measurements, Recurring [Member] | Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	53,614	43,789
Fair Value, Measurements, Recurring [Member] | Not for Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	3,937	2,109
Fair Value, Measurements, Recurring [Member] | Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	53,762	43,830
Fair Value, Measurements, Recurring [Member] | Not for Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	669	2,330
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	212	218
Assets measured at fair value, Available for sale securities	212	218
Assets measured at fair value, Total	212	218
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Financial Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	91	99
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Insurance Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	121	119
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	1,534,434	1,531,298
Assets measured at fair value, Available for sale equity securities	645	654
Assets measured at fair value, Available for sale securities	1,535,079	1,531,952
Derivative financial instruments	57,551	45,898
Assets measured at fair value, Total	1,592,630	1,577,850
Liabilities measured at fair value, Total	54,431	46,160
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	29,937	29,682
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	390,660	337,133
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	572,017	573,171
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Non-Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	10	11
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	6,843	7,880
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | States of the U.S. and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	13,175	13,158
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	16,231	16,178
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	505,561	554,085
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Financial Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	645	654
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	53,614	43,789
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Not for Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	3,937	2,109
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	53,762	43,830
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Not for Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	669	2,330
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	1,354	1,420
Assets measured at fair value, Available for sale equity securities	435	475
Assets measured at fair value, Available for sale securities	1,789	1,895
Assets measured at fair value, Total	1,789	1,895
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Non-Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale debt securities	1,354	1,420
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Financial Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value, Available for sale equity securities	$435	$475

Fair_Value_Measurements_Additi1

Fair Value Measurements - Additional Information about Assets Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring [Member], USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$1,895	$33,749
Total gains (losses) - realized/unrealized, Included in earnings		13,766
Total gains (losses) - realized/unrealized, Included in other comprehensive income	-52	5,676
Accretion included in earnings	1	662
Purchases	0	0
Issuances	0	0
Sales/redemptions		-51,527
Settlements	-55	-431
Transfers from Level 3	0	0
Transfers into Level 3	0	0
Balance at end of period	1,789	1,895
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period		31,595
Total gains (losses) - realized/unrealized, Included in earnings		13,766
Total gains (losses) - realized/unrealized, Included in other comprehensive income		5,608
Accretion included in earnings		657
Purchases	0	0
Issuances	0	0
Sales/redemptions		-51,527
Settlements		-99
Transfers from Level 3	0	0
Transfers into Level 3	0	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	475	410
Total gains (losses) - realized/unrealized, Included in other comprehensive income	-40	65
Purchases	0	0
Issuances	0	0
Transfers from Level 3	0	0
Transfers into Level 3	0	0
Balance at end of period	435	475
Residential Non-Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,420	1,744
Total gains (losses) - realized/unrealized, Included in other comprehensive income	-12	3
Accretion included in earnings	1	5
Purchases	0	0
Issuances	0	0
Settlements	-55	-332
Transfers from Level 3	0	0
Transfers into Level 3	0	0
Balance at end of period	$1,354	$1,420

Fair_Value_Measurements_Additi2

Fair Value Measurements - Additional Information about Assets Measured at Fair Value on Non-Recurring Basis (Detail) (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]
Impaired loans	$2,181
Other real estate owned	2,410
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	883	1,705
Other real estate owned	2,410	8,060
Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	190	177
Other real estate owned	977	5,695
Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	693	1,528
Other real estate owned	$1,433	$2,365

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Values of Corporation's Financial Instruments (Detail) (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 cash equivalents	$234,246	$287,393	$246,253	$213,981
Securities available for sale	1,537,080	1,534,065
Securities held to maturity	1,513,204	1,453,355
Securities held to maturity	1,536,449	1,468,258
Derivative assets	57,551	45,898
Deposits	11,806,043	11,382,208
Short-term borrowings	1,740,500	2,041,658
Long-term borrowings	541,474	541,443
Derivative liabilities	54,431	46,160
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	234,246	287,393
Securities available for sale	1,537,080	1,534,065
Securities held to maturity	1,536,449	1,468,258
Net loans and leases, including loans held for sale	11,119,711	10,956,544
Derivative assets	57,551	45,898
Accrued interest receivable	41,935	40,231
Deposits	11,812,401	11,382,402
Short-term borrowings	1,740,499	2,041,672
Long-term borrowings	541,955	539,007
Derivative liabilities	54,431	46,160
Accrued interest payable	6,511	6,689
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	234,246	287,393
Securities available for sale	1,537,080	1,534,065
Securities held to maturity	1,513,204	1,453,355
Net loans and leases, including loans held for sale	11,280,221	11,127,292
Derivative assets	57,551	45,898
Accrued interest receivable	41,935	40,231
Deposits	11,806,043	11,382,208
Short-term borrowings	1,740,500	2,041,658
Long-term borrowings	541,474	541,443
Derivative liabilities	54,431	46,160
Accrued interest payable	6,511	6,689
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	234,246	287,393
Securities available for sale	212	218
Accrued interest receivable	41,935	40,231
Deposits	9,217,159	8,771,173
Short-term borrowings	1,740,499	2,041,672
Accrued interest payable	6,511	6,689
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale	1,535,079	1,531,952
Securities held to maturity	1,532,588	1,463,945
Derivative assets	57,551	45,898
Deposits	2,595,242	2,611,229
Derivative liabilities	54,431	46,160
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale	1,789	1,895
Securities held to maturity	3,861	4,313
Net loans and leases, including loans held for sale	11,119,711	10,956,544
Long-term borrowings	$541,955	$539,007