Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 118,330	$ 103,284	$ 288,066	$ 210,800
Other comprehensive income, net of tax:
Net change in unrealized gains on available-for-sale investment securities	6,201	4,984	9,822	17,900
Foreign currency translation adjustments	3,136	(4,638)	4,143	(4,671)
Other comprehensive income	9,337	346	13,965	13,229
COMPREHENSIVE INCOME	$ 127,667	$ 103,630	$ 302,031	$ 224,029