Stock-based Awards (Details 2 - RSUs) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Weighted-Average Grant Date Fair Value
Stock based compensation expense	$ 5,157	$ 6,111	$ 11,542	$ 12,025
Non-vested restricted stock unit awards
Number of Shares
Non-vested at the beginning of period (in shares)			6,918,474
Granted (in shares)			5,007,558
Vested (in shares)			(1,911,185)
Canceled/forfeited (in shares)			(1,441,562)
Non-vested at the end of the period (in per share)	8,573,285		8,573,285
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of period (in dollars per share)			$ 4.63
Granted (in dollars per share)			4.81
Vested (in dollars per share)			4.78
Canceled/forfeited (in dollars per share)			4.55
Non-vested at the end of the period (in dollars per share)	$ 4.71		$ 4.71
Remaining stock based compensation expense for non vested restricted stock units	$ 37,000		$ 37,000
Weighted average period over which remaining stock based compensation expense for unvested awards is expected to be recognized (in years)			2 years 9 months 18 days
Stock based compensation expense	$ 4,200	$ 4,800	$ 8,900	$ 9,100