Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 740,200	$ 452,385	$ 362,431
Other comprehensive income (loss):
Foreign currency translation gains (losses), net of tax	83,165	(95,592)	(279,303)
Reclassification of foreign currency translation loss to investment, net of tax	31,381	0	0
Total other comprehensive income (loss)	114,546	(95,592)	(279,303)
Total comprehensive income	$ 854,746	$ 356,793	$ 83,128