Fair Value Measurements (Detail 5) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Financial Assets:
Cash and due from banks	$ 433,670,000us-gaap_CashAndDueFromBanks	$ 336,470,000us-gaap_CashAndDueFromBanks
Due from banks - interest-bearing	334,014,000us-gaap_InterestBearingDepositsInBanks	119,981,000us-gaap_InterestBearingDepositsInBanks
Securities purchased under resale agreements	200,302,000	200,108,000
Securities held-to-maturity	3,510,553,000	3,484,647,000
Loans and leases, net of allowance	20,601,497,000	20,027,057,000
Covered loans, net of allowance	470,484,000	502,371,000
FDIC indemnification asset	43,256,000us-gaap_FDICIndemnificationAsset	50,511,000us-gaap_FDICIndemnificationAsset
Investment in FHLB and FRB stock	58,400,000	58,400,000
Quoted Prices in Active Markets Level 1
Financial Assets:
Cash and due from banks	433,700,000	336,500,000
Due from banks - interest-bearing	334,000,000	120,000,000
Financial Liabilities:
Short-term borrowings		320,000,000
Significant Other Observable Inputs Level 2
Financial Assets:
Securities purchased under resale agreements	202,100,000	201,100,000
Securities held-to-maturity	3,510,600,000	3,484,600,000
Investment in FHLB and FRB stock	58,400,000	58,400,000
Financial Liabilities:
Deposits	27,849,000,000	27,435,100,000
Long-term debt	617,600,000	605,300,000
Significant Unobservable Inputs Level 3
Financial Assets:
Loans and leases, net of allowance	21,153,400,000	20,576,900,000
Covered loans, net of allowance	518,500,000	549,100,000
FDIC indemnification asset	34,600,000	40,200,000
Financial Liabilities:
Deposits	669,300,000	674,500,000
Short-term borrowings	4,400,000	2,900,000
Long-term debt	95,200,000	99,000,000
Carrying Amount
Financial Assets:
Cash and due from banks	433,700,000	336,500,000
Due from banks - interest-bearing	334,000,000	120,000,000
Securities purchased under resale agreements	200,000,000	200,000,000
Securities held-to-maturity	3,413,800,000	3,427,000,000
Loans and leases, net of allowance	20,601,500,000	20,027,100,000
Covered loans, net of allowance	470,500,000	502,400,000
FDIC indemnification asset	43,300,000	50,500,000
Investment in FHLB and FRB stock	58,400,000	58,400,000
Financial Liabilities:
Deposits	28,517,100,000	28,108,100,000
Short-term borrowings	4,400,000	322,900,000
Long-term debt	634,400,000	638,600,000
Fair Value
Financial Assets:
Cash and due from banks	433,700,000	336,500,000
Due from banks - interest-bearing	334,000,000	120,000,000
Securities purchased under resale agreements	202,100,000	201,100,000
Securities held-to-maturity	3,510,600,000	3,484,600,000
Loans and leases, net of allowance	21,153,400,000	20,576,900,000
Covered loans, net of allowance	518,500,000	549,100,000
FDIC indemnification asset	34,600,000	40,200,000
Investment in FHLB and FRB stock	58,400,000	58,400,000
Financial Liabilities:
Deposits	28,518,300,000	28,109,600,000
Short-term borrowings	4,400,000	322,900,000
Long-term debt	$ 712,800,000	$ 704,300,000

For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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