Components of Net Deferred Tax Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Allowance for doubtful accounts	$ 5.6	$ 8.2
Accrued expenses, current	1.1	1.2
Settlement accrual	59.3	0
Workers' compensation, current	7.0	6.7
Deferred revenue, current	(18.5)	(22.0)
Deferred tax asset, other, current	0.8	0.3
Current portion of deferred tax assets (liabilities)	55.3	(5.6)
Amortization of intangible assets, noncurrent	102.6	114.0
Property and equipment, noncurrent	(24.1)	(32.4)
Share-based compensation, noncurrent	3.9	5.2
Deferred tax asset, other, noncurrent	2.7	2.2
NOL Carryforward	5.3	4.0
Valuation Allowance	(0.2)	(0.2)
Noncurrent portion of deferred tax assets (liabilities)	90.2	92.8
Net deferred tax assets (liabilities)	$ 145.5	$ 87.2