Stock-based Awards (Details 2 - RSUs) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock-based Awards
Stock based compensation expense	$ 6,846	$ 5,900	$ 12,753	$ 11,792
Non-vested restricted stock unit awards
Stock-based Awards
Remaining stock based compensation expense for non vested restricted stock units	59,200		$ 59,200
Weighted average period over which remaining stock based compensation expense for unvested awards is expected to be recognized			3 years 4 months 6 days
Stock based compensation expense	$ 3,200	$ 2,200	$ 5,800	$ 4,300
Number of Shares
Non-vested at the beginning of period (in shares)			4,339,320
Granted (in shares)			1,974,776
Vested (in shares)			(764,642)
Canceled/forfeited (in shares)			(230,545)
Non-vested at the end of the period (in per share)	5,318,909		5,318,909
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of period (in dollars per share)			$ 7.85
Granted (in dollars per share)			18.33
Vested (in dollars per share)			8.10
Canceled/forfeited (in dollars per share)			7.46
Non-vested at the end of the period (in dollars per share)	$ 11.72		$ 11.72