Offsetting of Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Offsetting Assets and Liabilities [Line Items]
Gross And Net Amounts Of Assets Presented In The Statement Of Financial Condition	$ 168,388	$ 159,327
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments	164,496	151,419
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Received	478	582
Asset Net Amount	3,414	7,326
Gross And Net Amounts Of Liabilities Presented In the Statement Of Financial Condition	229,818	320,634
Gross Amount of Liabilities Not Offset in the Statement of Financial Condition, Financial Instruments	218,235	319,377
Cash Collateral Pledged	11,348	1,257
Liability Net Amount	235
Freestanding Derivatives
Offsetting Assets and Liabilities [Line Items]
Gross And Net Amounts Of Assets Presented In The Statement Of Financial Condition	5,680	10,343
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments	1,983	3,025
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Received	478	582
Asset Net Amount	3,219	6,736
Gross And Net Amounts Of Liabilities Presented In the Statement Of Financial Condition	12,957	4,282
Gross Amount of Liabilities Not Offset in the Statement of Financial Condition, Financial Instruments	1,983	3,025
Cash Collateral Pledged	10,739	1,257
Liability Net Amount	235
Reverse Repurchase Agreements
Offsetting Assets and Liabilities [Line Items]
Gross And Net Amounts Of Assets Presented In The Statement Of Financial Condition	162,708	148,984
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments	162,513	148,394
Asset Net Amount	195	590
Repurchase Agreements
Offsetting Assets and Liabilities [Line Items]
Gross And Net Amounts Of Liabilities Presented In the Statement Of Financial Condition	216,861	316,352
Gross Amount of Liabilities Not Offset in the Statement of Financial Condition, Financial Instruments	216,252	316,352
Cash Collateral Pledged	$ 609