Equity Incentive Plan (Details) - USD ($) $ / shares in Units, $ in Millions	8 Months Ended	12 Months Ended
	Aug. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 15, 2017
Restricted share awards
Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number				596,560
Summary of non-vested shares/units
Granted (in shares)	1,398,705
Vested (in shares)	(2,241,683)
Forfeited (in shares)	(1,027,415)
Unvested at the end of the period (in shares)	0	1,870,393
Weighted Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share)	$ 6.21
Granted (in dollars per share)	5.53
Vested (in dollars per share)	6.52
Forfeited (in dollars per share)	4.61
Unvested at the end of the period (in dollars per share)	$ 0.00	$ 6.21
Other Disclosures
Share-based compensation expense	$ (8.4)
2016 Performance Shares
Other Disclosures
Fair value assumptions, risk free interest rate		0.93%
Fair value assumptions, expected volatility rate		45.92%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		5.00%
2015 Performance Shares [Member]
Other Disclosures
Fair value assumptions, risk free interest rate			1.32%
Fair value assumptions, expected volatility rate			48.11%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			4.00%
2017 Performance Shares
Other Disclosures
Fair value assumptions, risk free interest rate	1.51%
Fair value assumptions, expected volatility rate	43.92%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	6.00%
Restricted Stock Units (RSUs) [Member]
Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number				1,363,293
Predecessor
Equity Incentive Plan
Maximum number of common shares available for issuance (in shares)	6,100,000
Other Disclosures
Total fair value of shares vested	$ 1.1
Predecessor | Restricted share awards
Other Disclosures
Share-based compensation expense	$ (2.7)