Equity - Restricted Stock Awards and Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Jan. 17, 2018	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based compensation expense			$ 2.9
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)		1,734,535
Granted (in shares)		541,915
Vested (in shares)		(34,963)
Forfeited (in shares)		(5,110)
Outstanding at end of period (in shares)		2,236,377
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)		$ 16.97
Granted (in dollars per share)		9.70
Vested (in dollars per share)		13.50
Forfeited (in dollars per share)		16.59
Outstanding at end of period (in dollars per share)		$ 15.26
Vesting period of awards		5 years
Share-based compensation expense		$ 4.1
Unamortized compensation expense		$ 26.8
Weighted average remaining vesting period		2 years
Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)		329,277
Granted (in shares)		392,948
Vested (in shares)		0
Forfeited (in shares)		0
Outstanding at end of period (in shares)		722,225
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)		$ 14.93
Granted (in dollars per share)		9.62
Vested (in dollars per share)		0
Forfeited (in dollars per share)		0
Outstanding at end of period (in dollars per share)		$ 12.04
Vesting period of awards		3 years
Shares of Class A Common Stock | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)		268,205
Vested (in shares)		0
Forfeited (in shares)		0
Outstanding at end of period (in shares)		268,205
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at beginning of period (in dollars per share)		$ 0
Vested (in dollars per share)		0
Forfeited (in dollars per share)		0
Outstanding at end of period (in dollars per share)		$ 0
Shares issued (in shares)	1,258,514