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
	Mar. 31, 2014	Mar. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 6,516	$ 946
Unrealized gain (loss) - pretax	8,023	5,795
Tax effect on unrealized gain	(2,764)	(2,230)
Unrealized gain (loss) - net of tax	5,259	3,565
Reclassification to realized gain - pretax	(1,934)	(1,216)
Tax effect on reclassification	666	463
Reclassification to realized gain - net of tax	(1,268)	(753)
Net current period other comprehensive income (loss)	3,991	2,812
Balance at end of period	10,507	3,758
Unrealized Gain on Securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	6,921	927
Unrealized gain (loss) - pretax	8,023	5,854
Tax effect on unrealized gain	(2,764)	(2,230)
Unrealized gain (loss) - net of tax	5,259	3,624
Reclassification to realized gain - pretax	(1,934)	(1,216)
Tax effect on reclassification	666	463
Reclassification to realized gain - net of tax	(1,268)	(753)
Net current period other comprehensive income (loss)	3,991	2,871
Balance at end of period	10,912	3,798
Cumulative Translation Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(405)	19
Unrealized gain (loss) - pretax	0	(59)
Tax effect on unrealized gain	0	0
Unrealized gain (loss) - net of tax	0	(59)
Reclassification to realized gain - pretax	0	0
Tax effect on reclassification	0	0
Reclassification to realized gain - net of tax	0	0
Net current period other comprehensive income (loss)	0	(59)
Balance at end of period	$ (405)	$ (40)