Commitments and Contingencies (Other Commitments and Contingencies) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Uninsured Risk [Member] | Other Non-Current Assets [Member]
Commitments and Contingencies [Line Items]
Cash collateral held by insurance carriers	$ 1.3	$ 1.4
Uninsured Risk [Member] | Workers Compensation, General And Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve	55.0	50.8
Self insurance reserve, non-current	34.1	31.3
Uninsured Risk [Member] | Group Insurance Policies [Member] | Health Insurance [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve	2.0	2.1
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member]
Commitments and Contingencies [Line Items]
Outstanding commitments	3
Performance Standby [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	500.0	1,100.0
Performance Standby [Member] | Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	225.0
Performance Standby [Member] | Plan [Member]
Commitments and Contingencies [Line Items]
Estimated cost to complete bonded projects	177.7	297.1
Financial Standby [Member] | Uninsured Risk [Member]
Commitments and Contingencies [Line Items]
Letters of credit, outstanding amount	57.4	57.4
Surety Bond [Member] | Uninsured Risk [Member] | Workers Compensation [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	10.9	10.9
Credit Facility [Member]
Commitments and Contingencies [Line Items]
Letters of credit, outstanding amount	132.8	134.8
Other Credit Facilities [Member]
Commitments and Contingencies [Line Items]
Letters of credit, outstanding amount	$ 10.5