Income Taxes - Narrative (Details) $ in Millions	3 Months Ended
	Dec. 31, 2016 USD ($) subsidiary	Dec. 31, 2015 USD ($)	Sep. 30, 2016 USD ($)
Income Tax Contingency [Line Items]
Valuation allowance	$ 3.2		$ 2.8
Interest and penalties	0.6		$ 1.2
Successor
Income Tax Contingency [Line Items]
Income tax expense (benefit)	(2.7)
Pre-tax (loss)	$ 11.0
Predecessor
Income Tax Contingency [Line Items]
Income tax expense (benefit)		$ 1.3
Pre-tax (loss)		$ (5.6)
U.S.
Income Tax Contingency [Line Items]
Number of active U.S. subsidiaries | subsidiary	2