Fair Value Measurement of Assets and Liabilities - Carrying Amounts and Estimated Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Deposits with stated maturities	$ 2,179,269	$ 2,508,766
Interest bearing deposits with banks	134,915	463,022
Total investment securities held to maturity	1,711,427	1,657,950
Accrued interest receivable	53,964	52,375
Carrying Amount [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	1,731,737	1,599,707
Carrying Amount [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Cash and due from banks	234,253	390,078
Interest bearing deposits with banks	134,915	463,022
Accrued interest receivable	53,964	52,375
Federal Reserve Bank and Federal Home Loan Bank stock	137,234	138,533
Deposits without stated maturities	9,139,993	8,755,252
Short-term borrowings	281,455	154,323
Accrued interest payable	16,442	15,917
Carrying Amount [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	139,255	99,869
Carrying Amount [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Deposits with stated maturities	2,179,269	2,508,766
Long-term borrowings	2,792,306	2,697,299
Junior subordinated debentures issued to capital trusts	41,089	40,927
Carrying Amount [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. government agency securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	4,427
Carrying Amount [Member] | Significant Other Observable Inputs (Level 2) [Member] | Obligations of states and political subdivisions [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	545,886	506,473
Carrying Amount [Member] | Significant Other Observable Inputs (Level 2) [Member] | Residential mortgage-backed securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	886,043	813,647
Carrying Amount [Member] | Significant Other Observable Inputs (Level 2) [Member] | Trust preferred securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	103,458	127,505
Carrying Amount [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate and other debt securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	52,668	52,213
Carrying Amount [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Net loans	11,453,995	10,892,599
Fair Value [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	1,711,427	1,657,950
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Cash and due from banks	234,253	390,078
Interest bearing deposits with banks	134,915	463,022
Accrued interest receivable	53,964	52,375
Federal Reserve Bank and Federal Home Loan Bank stock	137,234	138,533
Deposits without stated maturities	9,139,993	8,755,252
Short-term borrowings	281,455	154,323
Accrued interest payable	16,442	15,917
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	144,307	115,329
Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Deposits with stated maturities	2,206,427	2,563,726
Long-term borrowings	3,036,953	3,100,173
Junior subordinated debentures issued to capital trusts	45,261	40,776
Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. government agency securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	4,365
Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member] | Obligations of states and political subdivisions [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	543,151	531,966
Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member] | Residential mortgage-backed securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	871,021	838,116
Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member] | Trust preferred securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	91,489	113,657
Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate and other debt securities [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Total investment securities held to maturity	57,094	58,882
Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair value and carrying amounts of assets and liabilities not measured and not reported at fair value on the consolidated statement of financial condition
Net loans	$ 11,294,348	$ 10,908,742