Securities - Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Detail) $ in Thousands	Mar. 31, 2016 USD ($)
Investments, Debt and Equity Securities [Abstract]
Less than one year, Amortized Cost	$ 39,679
Due after one year through five years, Amortized Cost	50,683
Due after five years through ten years, Amortized Cost	2,768
Due after ten years, Amortized Cost	55,000
Total Amortized Cost	148,130
Less than one year, Estimated Fair Value	39,700
Due after one year through five years, Estimated Fair Value	51,249
Due after five years through ten years, Estimated Fair Value	2,779
Due after ten years, Estimated Fair Value	43,091
Total Estimated Fair Value	$ 136,819