Stock-based Compensation Plans and Awards - Restricted Stock Unit Activity (Details) - Restricted stock units (RSUs) shares in Thousands	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Restricted stock unit activity
Unvested beginning balance (in shares) | shares	1,921
Granted (in shares) | shares	2,612
Vested (in shares) | shares	(1,058)
Forfeited (in shares) | shares	(437)
Unvested ending balance (in shares) | shares	3,038
Grant date fair value
Unvested beginning balance (in dollars per share) | $ / shares	$ 7.99
Granted (in dollars per share) | $ / shares	6.46
Vested (in dollars per share) | $ / shares	7.89
Forfeited (in dollars per share) | $ / shares	7.98
Unvested ending balance (in dollars per share) | $ / shares	$ 6.71