Stockholders' Equity - Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Equity [Abstract]
Unrealized gains (losses) on available-for-sale securities, Before-Tax Amount	$ (4,974)	$ (2,626)	$ (2,454)	$ 2,157
Reclassification adjustment for amounts included in net income, Before-Tax Amount	(1,958)	(2,535)	(8,022)	(6,831)
Foreign currency translation adjustment, Before-Tax Amount	(1,351)	(2,568)	(3,797)	(2,182)
Total Other Comprehensive Income (Loss), Before-Tax Amount	(8,283)	(7,729)	(14,273)	(6,856)
Unrealized gains (losses) on available-for-sale securities, Tax (Expense) Benefit	1,940	1,024	957	(841)
Reclassification adjustment for amounts included in net income, Tax Benefit	772	989	3,153	2,665
Foreign currency translation adjustment, Tax Benefit	0	0	0	0
Total Other Comprehensive Income (Loss), Tax (Expense) Benefit	2,712	2,013	4,110	1,824
Unrealized gains (losses) on available-for-sale securities, Net-of-Tax Amount	(3,034)	(1,602)	(1,497)	1,316
Reclassification adjustment for amounts included in net income, Net-of-Tax Amount	(1,186)	(1,546)	(4,869)	(4,166)
Foreign currency translation adjustment, Net-of-Tax Amount	(1,351)	(2,568)	(3,797)	(2,182)
Other Comprehensive income (loss), net of tax	$ (5,571)	$ (5,716)	$ (10,163)	$ (5,032)