Amortized Cost and Fair Value of Available-for-Sale Securities and Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Available-for-sale, Amortized Cost
Within one year	$ 830
One to five years	37,262
Five to ten years	1,492
Totals	39,584	$ 19,288
Available-for-sale, Fair Value
Within one year	840
One to five years	37,217
Five to ten years	1,508
Totals	39,565	19,348
Held-to-maturity, Amortized Cost
Within one year	235
One to five years	0
Five to ten years	0
Totals	235	$ 450
Held-to-maturity, Fair Value
Within one year	236
One to five years	0
Five to ten years	0
Totals	$ 236