Stock-based Awards - Schedule of Restricted Stock Units Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Non-vested at the end of the period (in dollars per share)	4,284,438
Weighted-Average Grant Date Fair Value
Total stock-based compensation expense	$ 32,241	$ 24,739	$ 42,563
Restricted Stock Units (RSUs)
Stock-based Awards
Fair value of shares of restricted stock awards vested	$ 25,600	$ 11,800	$ 6,500
Number of Shares
Non-vested at the beginning of period (in shares)	4,339,320
Granted (in shares)	2,086,878
Vested (in shares)	(1,681,447)
Canceled/forfeited (in shares)	(460,313)
Non-vested at the end of the period (in dollars per share)	4,284,438	4,339,320
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of period (in dollars per share)	$ 7.85
Granted (in dollars per share)	18.26	$ 7.37	$ 8.17
Vested (in dollars per share)	9.60
Canceled/forfeited (in dollars per share)	10.10
Non-vested at the end of the period (in dollars per share)	$ 11.99	$ 7.85
Total stock-based compensation expense	$ 14,900	$ 9,900	$ 8,600