Investment Securities - Additional Information (Detail) (USD $)	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Securities pledged as collateral	$ 517,400,000
FHLB pledged investment securities	0
Proceeds from sale of investment securities	37,800,000	139,200,000
Net gains from sale of investment securities	578,000	1,600,000
Losses from sale of investment securities	0
Unamortized premiums	25,400,000
Unaccreted discounts	207,000
Owned investment securities	740,803,000		747,718,000
Total unrealized losses on securities	21,471,000		34,754,000
Mortgage-Backed Securities ("MBS") [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted average duration of MBS portfolio	5 years 4 months 24 days
OTTI on evaluation of securities	$ 0

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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-Publisher FASB

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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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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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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The carrying value as of the balance sheet date of the assets received as collateral against securities loaned to other broker-dealers. Borrowers of securities generally are required to provide collateral to the lenders of securities, commonly cash but sometimes other securities or standby letters of credit, with a value slightly higher than that of the securities borrowed. In instances where the entity is permitted to sell or re-pledge these securities, the entity reports the fair value of the collateral received and the related obligation to return the collateral as a liability.

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Amount of accumulated pre-tax unrealized loss on investments on securities classified as available-for-sale securities impacting investments.

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Weighted Average Remaining Expected Life Of Residential Mortgage Backed Securities Available For Sale One

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