Supplemental Cash Flow Information - Reconciliation of Total Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Cash Flow Statements Captions [Line Items]
Cash and cash equivalents	$ 27.2	$ 35.7	$ 61.9
Cash and cash equivalents—discontinued operations		0.1	1.0
Restricted cash and restricted cash equivalents	1.0	3.9
Cash, cash equivalents, restricted cash and restricted cash equivalents, end of period	32.7	43.3	65.7	$ 50.8
Prepaid Expenses, Supplies and Other Current Assets
Condensed Cash Flow Statements Captions [Line Items]
Restricted cash and restricted cash equivalents	1.0	3.9	2.8
Other Noncurrent Assets
Condensed Cash Flow Statements Captions [Line Items]
Restricted cash and restricted cash equivalents	$ 4.5	$ 3.6	$ 0.0