Income Taxes Net Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2017	Apr. 01, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor
Unrecognized Tax Benefits Recorded in Balance Sheet [Line Items]
Unrecognized Tax Benefit Recorded in Deferred Income Taxes	$ 10.9
Unrecognized Tax Benefit Recorded in Other Noncurrent Liabilities	1.8
Net Unrecognized Tax Benefit	12.7
Unrecognized Tax Benefits	$ 12.7	$ 12.5
Predecessor
Unrecognized Tax Benefits Recorded in Balance Sheet [Line Items]
Unrecognized Tax Benefit Recorded in Deferred Income Taxes			$ 8.9
Unrecognized Tax Benefit Recorded in Other Noncurrent Liabilities			11.2
Net Unrecognized Tax Benefit			20.1
Unrecognized Tax Benefits		$ 12.5	$ 20.1	$ 22.9	$ 44.5