Stock-based Payments - Summary of Time-based Stock Options (Details) - Time-Based Options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Outstanding, beginning balance (in shares)	3,300,000	3,500,000	2,200,000
Granted (in shares)	0	200,000	100,000
Granted through modification (in shares)			1,300,000
Exercised (in shares)	(600,000)	(300,000)	(0.0)
Forfeited (in shares)	(100,000)	(100,000)	(100,000)
Outstanding, ending balance (in shares)	2,600,000	3,300,000	3,500,000	2,200,000
Exercisable as of December 31, 2018 (in shares)	1,900,000
Weighted Average Exercise Price per Share
Outstanding, beginning balance (USD per share)	$ 11.23	$ 10.88	$ 10.65
Granted (USD per share)	0	17.00	17.00
Granted through modification (USD per share)			11.06
Exercised (USD per share)	10.05	10.19	12.00
Forfeited (USD per share)	11.19	12.58	11.79
Outstanding, ending balance (USD per share)	11.51	$ 11.23	$ 10.88	$ 10.65
Exercisable (USD per share)	$ 10.67
Weighted average remaining contractual term, outstanding	5 years 10 months 24 days	6 years 9 months 18 days	8 years 6 months	8 years 7 months 6 days
Weighted average remaining contractual term, exercisable	5 years 8 months 12 days
Outstanding, Aggregate Intrinsic Value	$ 24.3	$ 11.8	$ 13.8	$ 14.2
Exercisable aggregate intrinsic value	$ 19.0