Securities - Contractual Maturity of Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013
Amortized Cost And Fair Value Debt Securities [Abstract]
Less than one year, Amortized Cost	$ 57,609
Due after one year through five years, Amortized Cost	107,024
Due after five years through ten years, Amortized Cost	1,233
Due after ten years, Amortized Cost	55,000
Total Amortized Cost	220,866
Less than one year, Estimated Fair Value	57,851
Due after one year through five years, Estimated Fair Value	107,003
Due after five years through ten years, Estimated Fair Value	1,191
Due after ten years, Estimated Fair Value	44,876
Total Estimated Fair Value	$ 210,921