Borrowings - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Borrowings [Line Items]
Line of credit amount available for borrowing		$ 1,100.0
Pledged collateral for line of credit		498.3
Total pledged collateral		485.4
Pledged collateral for overnight funds		80
Pledged collateral for FHLB advances	440.1	405.4
Residential Portfolio Segment
Borrowings [Line Items]
Pledged under blanket lien	399.1	319.2
Commercial Portfolio Segment
Borrowings [Line Items]
Pledged under blanket lien	552.6	514.8
Home Equity Lines Of Credit
Borrowings [Line Items]
Pledged under blanket lien	313.6	322.0
Multifamily Loans
Borrowings [Line Items]
Pledged under blanket lien	8.0	13.0
Federal Reserve and Correspondent Banks
Borrowings [Line Items]
Line of credit amount available for borrowing	411.6	315.2
Unsecured line of credit available for borrowing	55	55
FHLB
Borrowings [Line Items]
Percentage of principal and accrued interest of retail repurchase agreements collateralized	102.50%
Line of credit amount available for borrowing	1,200.0
Pledged collateral for line of credit	$ 699.1

The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for FHLB debt obligations, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

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- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

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- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for debt facilities other than FHLB loans, repurchase agreements and letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

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- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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