Derivatives (Effect of Derivative Financial Instruments on Our Consolidated Statements of Operations) (Detail) - USD ($) $ in Millions	8 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Loss recognized in Other Comprehensive Income (Loss) on derivatives		$ 1.5	$ (2.4)	$ (1.9)
Loss reclassified from Accumulated Other Comprehensive Income (Loss) into income (effective portion)	$ (0.1)	(1.5)	(1.2)
Gain (loss) recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)		0.1	0.5	1.8
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from Accumulated Other Comprehensive Income (Loss) into income (effective portion)		(5.1)	(5.0)	(4.3)
Gain (loss) recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)		$ (0.1)	$ (0.5)	$ (1.8)