Commitments and Contingencies (Other Commitments and Contingencies) (Narrative) (Details) (USD $)	0 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Uninsured Risk [Member] | Workers Compensation, General And Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve	$ 60,300,000	$ 50,800,000
Uninsured Risk [Member] | Workers Compensation, General And Automobile Policies [Member] | Other Non-Current Liabilities [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve, non-current	36,300,000	31,300,000
Uninsured Risk [Member] | Workers Compensation, General And Automobile Policies [Member] | Other Non-Current Assets [Member]
Commitments and Contingencies [Line Items]
Cash collateral held by insurance carriers	1,100,000	1,400,000
Uninsured Risk [Member] | Group Insurance Policies [Member] | Medical Insurance [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve	1,900,000	2,100,000
Unconsolidated Affiliates [Member] | Financial Support [Member]
Commitments and Contingencies [Line Items]
Unconsolidated affiliates, outstanding commitments	0
Performance Guarantee [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	748,600,000	1,100,000,000
Performance Guarantee [Member] | Projected Estimate [Member]
Commitments and Contingencies [Line Items]
Bonded projects, costs to complete	53,100,000	297,100,000
Financial Guarantee [Member] | Uninsured Risk [Member] | Workers Compensation, General And Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Letters of credit, outstanding amount	57,200,000	57,400,000
Surety Bond [Member] | Uninsured Risk [Member] | Workers Compensation [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	13,000,000	10,900,000
Credit Facility [Member]
Commitments and Contingencies [Line Items]
Letters of credit, outstanding amount	$ 135,600,000	$ 134,800,000