Debt Securities According Contractual Terms (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013
Debt And Receivables Securitization [Line Items]
Amortized costs, In one year or less	$ 67,127
Amortized costs, After one year through five years	185,181
Amortized costs, After five years through ten years	218,893
Amortized costs, After ten years	37,071
Amortized costs, Total	508,272
Fair Values, In one year or less	67,161
Fair Values, After one year through five years	189,487
Fair Values, After five years through ten years	221,719
Fair Values, After ten years	36,886
Debt securities, fair values total	$ 515,253