Fair Value Measurements - Summary of Company's Securities Available-for-Sale (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 58,393	$ 50,355
Gross unrealized gains	74	859
Gross unrealized losses	(30)	(6)
Securities available-for-sale, Estimated Fair value	58,437	51,208
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	8,686	17,941
Gross unrealized gains	10	10
Gross unrealized losses		(4)
Securities available-for-sale, Estimated Fair value	8,696	17,947
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	49,707	2,159
Gross unrealized gains	64
Gross unrealized losses	(30)	(2)
Securities available-for-sale, Estimated Fair value	49,741	2,157
U.S. Government Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		30,255
Gross unrealized gains		849
Gross unrealized losses
Securities available-for-sale, Estimated Fair value		$ 31,104