Repurchase Agreements - Remaining Maturities, Collateral Types and Weighted Average Rate (Parenthetical) (Detail)	Sep. 30, 2015	Dec. 31, 2014
Repurchase Agreements:
Percentage of repurchase agreements, with remaining maturity over one year	14.00%	15.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration