Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	34.30%	30.20%	34.40%	32.60%
Net payable related to spin-off tax liabilities	$ 36.2		$ 36.2		$ 35.1
Liability for income taxes associated with uncertain tax positions	24.4		24.4		24.1
Offsetting tax benefits related to uncertain tax positions	3.4		3.4		3.4
Uncertain tax positions, net	21.0		21.0		20.7
Accrued interest and penalties on uncertain tax positions	$ 9.5		9.5		8.9
Other tax benefits related to interest and penalties of uncertain tax positions			$ 4.0		$ 3.7
Unrecognized tax positions increase decrease, months			It is reasonably possible that the amount of the unrecognized benefit with respect to certain of the Company’s unrecognized tax positions may significantly decrease within the next 12 months. These changes may be the result of ongoing audits or the expiration of federal and state statutes of limitations for the assessment of taxes.