Accumulated Other Comprehensive Income - Changes, net of tax, in Accumulated other comprehensive income are as follows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Changes, net of tax, in Accumulated other comprehensive income are as follows: [Abstract]
Balance at January 1, 2013			$ 927
Balance at January 1, 2013			19
Balance at January 1, 2013			946
Other comprehensive income (loss) before reclassifications, net of taxes			3,543
Other comprehensive income (loss) before reclassifications, net of taxes	23	(27)	(36)	(22)
Other comprehensive income (loss) before reclassifications, net of taxes			3,507
Amounts reclassified to realized loss			(29)
Amounts reclassified to realized loss			(29)
Net current period other comprehensive income	643	75	3,514	858
Net current period other comprehensive income			(36)
Net current period other comprehensive income			3,478
Balance at June 30, 2013	4,441		4,441
Balance at June 30, 2013	(17)		(17)
Balance at June 30, 2013	$ 4,424		$ 4,424