Earnings Per Share - Additional Disclosures (Details) shares in Millions	12 Months Ended
	Dec. 31, 2018 shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares
Class of Stock [Line Items]
Basic (in shares)	147.6	88.7	65.9
Conversion of Units to shares of Class A common stock, ratio (as a percent)		1
Expected Effective Income Tax Rate Reconciliation, Percent		(16.70%)
Common Class B
Class of Stock [Line Items]
Basic (in shares)	0.0	63.1	0.0
Antidilutive securities excluded from EPS (in shares)			84.8
Common Class A
Class of Stock [Line Items]
Basic (in shares)	147.6	88.7	65.9
Dilutive effect of unvested restricted shares of Class A common stock (in shares)	0.6	0.6	2.0