Stock-based Compensation - Restricted Stock Units (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period for vesting	4 years
Vesting percentage	25.00%
Total RSUs
Outstanding at the beginning of the period (in shares)	1,391
Granted (in shares)	976
Forfeited / Canceled (in shares)	(337)
Vested (in shares)	(537)
Outstanding at the end of the period (in shares)	1,493	1,391
Weighted-Average Grant-Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 16.01
Granted (in dollars per share)	10.66	$ 16.12	$ 19.35
Forfeited (in dollars per share)	14.81
Vested (in dollars per share)	17.54
Outstanding at the end of the period (in dollars per share)	$ 12.23	$ 16.01
Aggregate intrinsic value, vested	$ 7.3	$ 4.8	$ 2.9
RSUs | Non-Employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
New Century Health | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		1 year