Stock-based Awards (Details 2 - RSUs) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted-Average Grant Date Fair Value
Stock based compensation expense	$ 8,972	$ 6,846	$ 18,069	$ 12,753
Non-vested restricted stock unit awards
Number of Shares
Non-vested at the beginning of period (in shares)			4,284,438
Granted (in shares)			3,025,260
Vested (in shares)			(852,017)
Canceled/forfeited (in shares)			(558,775)
Non-vested at the end of the period (in per share)	5,898,906		5,898,906
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of period (in dollars per share)			$ 11.99
Granted (in dollars per share)			9.69
Vested (in dollars per share)			11.24
Canceled/forfeited (in dollars per share)			10.87
Non-vested at the end of the period (in dollars per share)	$ 11.02		$ 11.02
Remaining stock based compensation expense for non vested restricted stock units	$ 61,700		$ 61,700
Weighted average period over which remaining stock based compensation expense for unvested awards is expected to be recognized			2 years 11 months 27 days
Stock based compensation expense	$ 5,200	$ 3,200	$ 9,600	$ 5,800