Employee Equity Incentive Plans and Stock-Based Compensation Expense - Summary of Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 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	308
Exercised | shares	(76)
Forfeited | shares	(54)
Outstanding, March 31, 2016 | shares	5,620
Exercisable, March 31, 2016 | shares	3,249
Vested and expected to vest, March 31, 2016 | shares	5,452
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	32.27
Exercised | $ / shares	9.33
Forfeited | $ / shares	42.41
Outstanding, March 31, 2016 | $ / shares	39.45
Exercisable, March 31, 2016 | $ / shares	33.40
Vested and expected to vest, March 31, 2016 | $ / shares	$ 39.22
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 18 days
Weighted Average Remaining Contractual Term (in years), Exercisable, September 30, 2015	2 years 314 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest, September 30, 2015	3 years 363 days
Intrinsic Value, Outstanding, September 30, 2015 | $	$ 13,888
Intrinsic Value, Exercisable, September 30, 2015 | $	13,223
Intrinsic Value, Vested and expected to vest, September 30, 2015 | $	$ 13,810