Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock and Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Beginning Balance (in shares) at Dec. 31, 2014		422,910,887
Beginning Balance at Dec. 31, 2014	$ 1,857,708	$ 1,042,870	$ (4,446)	$ 819,284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	122,641			122,641
Other comprehensive income (loss)	$ (38,862)		(38,862)
Issuance of common stock upon exercise of options (in shares)	5,029,553	5,029,553
Issuance of common stock upon exercise of options	$ 77,334	$ 77,334
Stock-based compensation expense	124,725	124,725
Excess stock option income tax benefits	79,880	$ 79,880
Ending Balance (in shares) at Dec. 31, 2015		427,940,440
Ending Balance at Dec. 31, 2015	2,223,426	$ 1,324,809	(43,308)	941,925
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	186,678			186,678
Other comprehensive income (loss)	$ (5,257)		(5,257)
Issuance of common stock upon exercise of options (in shares)	2,113,772	2,113,772
Issuance of common stock upon exercise of options	$ 36,979	$ 36,979
Stock-based compensation expense	173,675	173,675
Excess stock option income tax benefits	64,299	$ 64,299
Ending Balance (in shares) at Dec. 31, 2016		430,054,212
Ending Balance at Dec. 31, 2016	2,679,800	$ 1,599,762	(48,565)	1,128,603
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	558,929			558,929
Other comprehensive income (loss)	$ 28,008		28,008
Issuance of common stock upon exercise of options (in shares)	3,338,474	3,338,474
Issuance of common stock upon exercise of options	$ 89,425	$ 89,425
Stock-based compensation expense	182,209	$ 182,209
Ending Balance (in shares) at Dec. 31, 2017		433,392,686
Ending Balance at Dec. 31, 2017	3,581,956	$ 1,871,396	$ (20,557)	1,731,117
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-09 [Member]	$ 43,585			$ 43,585