Debt Securities According Contractual Terms (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Debt And Receivables Securitization [Line Items]
Amortized costs, In one year or less	$ 73,847
Amortized costs, After one year through five years	169,797
Amortized costs, After five years through ten years	206,461
Amortized costs, After ten years	34,171
Amortized costs, Total	484,276
Fair Values, In one year or less	73,886
Fair Values, After one year through five years	173,354
Fair Values, After five years through ten years	208,608
Fair Values, After ten years	34,162
Debt securities, fair values total	$ 490,010