Debt and Redeemable Preferred Stock - Short-term and Long-term Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Long-term debt due within one year, net
Capital leases due within one year	$ 3.6	$ 2.0
Term loan due within one year		0.3
Total long-term debt due within one year, net	3.6	2.3
Long-term debt, net
Total long-term debt, net	4.4	354.2
Total debt	8.0	356.5
Senior Secured Notes
Long-term debt, net
Principal amount outstanding		305.0
Unamortized original issue discount and debt issuance costs		(10.1)
Long-term debt, net		294.9
Revolving Credit Facilities
Long-term debt, net
Principal amount outstanding		57.0
Unamortized original issue discount and debt issuance costs		(1.5)
Long-term debt, net		55.5
Term Loan
Long-term debt, net
Term Loan		1.2
Capital Leases
Long-term debt, net
Capital leases	$ 4.4	$ 2.6