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Commitments and Contingencies (Other Commitments and Contingencies) (Narrative) (Details) - USD ($)			3 Months Ended	4 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2015	Aug. 03, 2015
Uninsured Risk [Member] \| Workers Compensation, General and Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve	$ 71,200,000	$ 70,300,000	$ 71,200,000
Uninsured Risk [Member] \| Workers Compensation, General and Automobile Policies [Member] \| Other Long-Term Liabilities [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve, non-current	43,400,000	39,600,000	43,400,000
Uninsured Risk [Member] \| Workers Compensation, General and Automobile Policies [Member] \| Other Long-Term Assets [Member]
Commitments and Contingencies [Line Items]
Cash collateral held by insurance carriers	1,400,000	1,200,000	1,400,000
Uninsured Risk [Member] \| Employee Group Medical Claims Policies [Member]
Commitments and Contingencies [Line Items]
Self insurance reserve	4,200,000	4,400,000	4,200,000
Unconsolidated Affiliates [Member] \| Financial Support [Member] \| Canadian Dollars [Member]
Commitments and Contingencies [Line Items]
Unconsolidated affiliates, amounts paid			9,600,000
Unconsolidated affiliates, outstanding commitments	0	0	0
Unconsolidated Affiliates [Member] \| Financial Support [Member] \| Canadian Dollars [Member] \| Subsequent Event [Member]
Commitments and Contingencies [Line Items]
Unconsolidated affiliates, amounts paid				$ 6,800,000
Performance and Payment Bonds [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	665,600,000	748,300,000	665,600,000
Performance and Payment Bonds [Member] \| Estimate [Member]
Commitments and Contingencies [Line Items]
Bonded projects, costs to complete	51,600,000	60,100,000
Surety Bond [Member] \| Uninsured Risk [Member] \| Workers Compensation [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount	13,000,000	13,000,000	13,000,000
Credit Facility [Member]
Commitments and Contingencies [Line Items]
Letters of credit issued	153,200,000	153,600,000	153,200,000
Credit Facility [Member] \| Financial Guarantees [Member] \| Uninsured Risk [Member] \| Workers Compensation, General and Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Letters of credit issued	$ 75,000,000	$ 75,000,000	$ 75,000,000