Other Comprehensive Income - Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income Loss [Line Items]
Total other comprehensive income, Gross		$ 1.3	$ 5.7	$ 1.1
Total other comprehensive income, Tax		(0.5)	(2.2)	(0.4)
Total other comprehensive income, net of tax		0.8	3.5	0.7
Net unrealized losses from cash flow hedges	[1]	(2.8)	(3.6)
Total accumulated other comprehensive loss		(2.8)	(3.6)
Accumulated Gain on Cash Flow Hedges [Member]
Other Comprehensive Income Loss [Line Items]
Unrealized gain on cash flow hedges, Gross		0.0	4.3	0.0
Reclassification from AOCI to net income, Gross		1.3	1.4	1.1
Total other comprehensive income, Gross		1.3	5.7	1.1
Unrealized gain on cash flow hedges, Tax		0.0	(1.5)	0.0
Reclassification from AOCI to net income, Tax		(0.5)	(0.7)	(0.4)
Total other comprehensive income, Tax		(0.5)	(2.2)	(0.4)
Unrealized gain on cash flow hedges, Net		0.0	2.8	0.0
Reclassification from AOCI to net income, Net		0.8	0.7	0.7
Total other comprehensive income, net of tax		$ 0.8	$ 3.5	$ 0.7

[1] Net of tax benefit of $1.8 million and $2.3 million as of December 31, 2016 and 2015, respectively.