Employee Equity Incentive Plans and Stock-Based Compensation Expense - Summary of Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, December 31, 2015 | shares	5,442
Granted | shares	1,278
Exercised | shares	(285)
Forfeited | shares	(168)
Outstanding, June 30, 2016 | shares	6,267
Exercisable, June 30, 2016 | shares	3,453
Vested and expected to vest, June 30, 2016 | shares	6,050
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, December 31, 2015 | $ / shares	$ 39.46
Granted | $ / shares	34.53
Exercised | $ / shares	9.61
Forfeited | $ / shares	38.66
Outstanding, June 30, 2016 | $ / shares	39.81
Exercisable, June 30, 2016 | $ / shares	37.45
Vested and expected to vest, June 30, 2016 | $ / shares	$ 39.73
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Term (in years), Outstanding, September 30, 2015	4 years 163 days
Weighted Average Remaining Contractual Term (in years), Exercisable, September 30, 2015	3 years 85 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest, September 30, 2015	4 years 135 days
Intrinsic Value, Outstanding, September 30, 2015 | $	$ 6,374
Intrinsic Value, Exercisable, September 30, 2015 | $	5,848
Intrinsic Value, Vested and expected to vest, September 30, 2015 | $	$ 6,316