Stockholders' Equity Successor Preferred Stock Activity (Details) - shares shares in Millions	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018
Class of Stock [Line Items]
Shares outstanding at the beginning of the period	30.0	13.5
Shares converted to Common Stock	(17.2)	(13.5)
Shares issued for payable in-kind preferred stock dividends	0.7	0.0
Shares outstanding at the end of the period	13.5	0.0