Stockholders' Equity (Summary of Activity Related to Stock Option Plans) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended			96 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Available for Grant, Beginning Balances	16,845,316	20,025,208	23,844,219
Options Outstanding, Number of Shares, Beginning Balances	20,995,756	22,845,417	24,688,286
Options Outstanding, Number of Shares, Granted	(3,555,363)	(3,179,892)	(3,819,011)
Options Outstanding, Number of Shares, Exercised	(2,113,772)	(5,029,553)	(5,661,880)
Shares Available for Grant, Ending Balances	13,289,953.000	16,845,316	20,025,208	20,025,208
Options Outstanding, Number of Shares, Ending Balances	22,437,347	20,995,756	22,845,417	22,845,417
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options Outstanding, Weighted-Average Exercise Price, Beginning Balances (in USD per share)	$ 32.39	$ 21.65	$ 13.61
Options Outstanding, Weighted-Average Exercise Price, Granted (in USD per share)	102.03	82.67	57.55
Options Outstanding, Weighted-Average Exercise Price, Exercised (in USD per share)	17.48	15.38	10.81
Options Outstanding, Weighted-Average Exercise Price, Ending Balances (in USD per share)	$ 44.83	$ 32.39	$ 21.65	$ 21.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options Outstanding, Number of Shares, Vested and exercisable	22,437,347
Options Outstanding, Weighted-Average Exercise Price, Vested and exercisable (in USD per share)	$ 44.83
Weighted-Average Remaining Contractual Term, Vested and exercisable (in Years)	6 years 2 months 5 days
Aggregate Intrinsic Value, Vested and exercisable	$ 1,772,185
Expiration period				10 years