Fair Value Measurements - Summary of Company's Securities Available-for-Sale (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 14,464	$ 50,355
Gross unrealized gains	15	859
Gross unrealized losses		(6)
Securities available-for-sale, Estimated Fair value	14,479	51,208
Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	12,342	17,941
Gross unrealized gains	11	10
Gross unrealized losses		(4)
Securities available-for-sale, Estimated Fair value	12,353	17,947
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	2,122	2,159
Gross unrealized gains	4
Gross unrealized losses		(2)
Securities available-for-sale, Estimated Fair value	2,126	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