Commitment and Contingencies - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Operating lease expense		$ 8.1	$ 7.7	$ 5.5
Pretax liability related to the non-income tax matters			0.2	0.8
Taxes paid to settle with certain states		$ 1.4	$ 0.1	0.3
Settlement				0.8
Payments for legal settlement	$ 0.8
Tax Years 2007 to 2012 [Member]
Loss Contingencies [Line Items]
Pretax liability related to the non-income tax matters				$ 0.4