Debt Securities According Contractual Terms (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Amortized costs, In one year or less	$ 2,674
Amortized costs, After one year through five years	290,264
Amortized costs, After five years through ten years	206,336
Amortized costs, After ten years	31,904
Amortized costs, Total	531,178
Fair Values, In one year or less	2,711
Fair Values, After one year through five years	296,991
Fair Values, After five years through ten years	213,300
Fair Values, After ten years	33,562
Debt securities, fair values total	$ 546,564