Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Accrued self-insurance	$ 26.0	$ 27.2
Operating loss carryforwards	17.8	9.0
Compensation and benefits	20.7	22.3
Bad debt	5.0	5.8
Other	15.9	9.3
Valuation allowance	(0.2)	(0.1)
Total deferred tax assets	85.2	73.5
Deferred tax liabilities:
Property and equipment	114.3	92.6
Goodwill	47.5	44.7
Other intangible assets	44.0	32.6
Other	11.3	13.8
Total deferred tax liabilities	257.0	212.0
Net deferred tax liabilities	(171.8)	(138.5)
Long-Term Contracts [Member]
Deferred tax liabilities:
Deferred income	28.7	17.0
Ec Source [Member]
Deferred tax liabilities:
Deferred income	$ 11.2	$ 11.3