Investment Securities Available for Sale - Contractual Maturity of Investment Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Investments Debt And Equity Securities [Abstract]
Less than one year, Amortized Cost	$ 50,482
Due after one year through five years, Amortized Cost	123,777
Due after five years through ten years, Amortized Cost	987
Due after ten years, Amortized Cost	55,000
Total Amortized Cost	230,246
Less than one year, Estimated Market Value	50,711
Due after one year through five years, Estimated Market Value	123,585
Due after five years through ten years, Estimated Market Value	951
Due after ten years, Estimated Market Value	44,562
Total Estimated Market Value	$ 219,809