Stock-based Awards (Details 2 - RSUs) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Weighted-Average Grant Date Fair Value
Stock based compensation expense	$ 5,607	$ 6,805	$ 17,632	$ 30,260
Non-vested restricted stock unit awards
Number of Shares
Non-vested at the beginning of period (in shares)			5,890,992
Granted (in shares)			6,118,702
Vested (in shares)			(2,453,805)
Canceled/forfeited (in shares)			(1,476,016)
Non-vested at the end of the period (in per share)	8,079,873		8,079,873
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of period (in dollars per share)			$ 7.96
Granted (in dollars per share)			2.91
Vested (in dollars per share)			3.43
Canceled/forfeited (in dollars per share)			7.38
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	$ 33,400		$ 33,400
Weighted average period over which remaining stock based compensation expense for unvested awards is expected to be recognized			2 years 3 months 18 days
Stock based compensation expense	$ 4,300	$ 5,000	$ 13,400	$ 18,700