Share-Based Compensation - 2014 Incentive Plan (Details) - 2014 Incentive Plan - USD ($) $ / shares in Units, $ in Millions				4 Months Ended		9 Months Ended		12 Months Ended
	Jul. 30, 2018	May 14, 2018	May 07, 2018	Oct. 07, 2018	Oct. 08, 2017	Oct. 07, 2018	Oct. 08, 2017	Dec. 31, 2017	Mar. 13, 2017
Share-Based Compensation
Maximum equity-based incentive awards (in shares)									9,200,000
Restricted stock
Share-Based Compensation
Vesting rights (as a percent)		33.33%
Vesting period		3 years
Stock awards retained for the purpose of grantee's income tax obligations (in shares)						112,880
Shares
Outstanding at the beginning of the period (in shares)						1,954,604
Granted (in shares)	1,370,576	1,370,576	1,370,576			1,370,576
Forfeited (in shares)						(25,334)
Vested (in shares)						(543,988)
Outstanding at the end of the period (in shares)				2,755,858		2,755,858		1,954,604
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)						$ 11.38
Granted (in dollars per share)						4.97
Forfeited (in dollars per share)						9.59
Vested (in dollars per share)						13.04
Outstanding at the end of the period (in dollars per share)				$ 7.88		$ 7.88		$ 11.38
Additional disclosures
Share-based compensation expense recognized (in dollars)				$ 2.9	$ 2.6	$ 7.8	$ 5.0
Unrecognized compensation cost				$ 12.4		$ 12.4
Weighted-average period over which expense is expected to be recognized						1 year 8 months 23 days
Time-Based Options
Shares
Outstanding at the beginning of the period (in shares)						3,254,544
Granted (in shares)						12,593
Forfeited (in shares)						(54,652)
Expired (in shares)						(14,656)
Outstanding at the end of the period (in shares)				3,197,829		3,197,829		3,254,544
Exercisable at the end of the period (in shares)				1,945,169		1,945,169
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)						$ 12.89
Granted (in dollars per share)						5.95
Forfeited (in dollars per share)						12.54
Expired (in dollars per share)						13.26
Outstanding at the end of the period (in dollars per share)				$ 12.86		12.86		$ 12.89
Exercisable at the end of the period (in dollars per share)				$ 12.65		$ 12.65
Weighted-Average Remaining Contractual Term, Outstanding						6 years 11 months 1 day		7 years 8 months 1 day
Weighted-Average Remaining Contractual Term, Exercisable						6 years 5 months 19 days
Additional disclosures
Share-based compensation expense recognized (in dollars)				$ 0.7	$ 1.3	$ 2.3	$ 2.8
Unrecognized share-based compensation expense				$ 2.2		$ 2.2
Weighted-average period over which expense is expected to be recognized						1 year 4 months 17 days
Option shares
Share-Based Compensation
Maximum equity-based incentive awards (in shares)	12,593
Vesting rights (as a percent)	25.00%
Vesting period	4 years