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Commitments and Contingencies (Details) - USD ($)			1 Months Ended
	Jul. 03, 2017	Apr. 05, 2017	Sep. 30, 2017	Dec. 31, 2014	Dec. 31, 2017
URS | Design build contractor
Commitments and Contingencies
Damages claimed, value	$ 70,000,000	$ 8,200,000
Standby letter of credit
Commitments and Contingencies
Contingency liability			$ 503,800,000		$ 515,700,000
Surety Bond
Commitments and Contingencies
Surety bonds issued			5,700,000,000		5,700,000,000
AECOM USA, Inc. | Minimum
Commitments and Contingencies
Damages claimed, value			$ 100,000
DOE Deactivation, Demolition, And Removal Project | Department of Energy | Maximum
Commitments and Contingencies
Cost-reimbursement at risk					106,000,000
DOE Deactivation, Demolition, And Removal Project | WGI Ohio and DOE | Minimum
Commitments and Contingencies
Cost-reimbursement at risk					106,000,000
DOE Deactivation, Demolition, And Removal Project | WGI Ohio and DOE | Maximum
Commitments and Contingencies
Cost-reimbursement at risk					146,000,000
DOE Deactivation, Demolition, And Removal Project | WGI Ohio
Commitments and Contingencies
Claim to DOE, including additional fees				$ 103,000,000
Possible costs which may exceed contracted amounts				$ 100,000,000
DOE Deactivation, Demolition, And Removal Project | WGI Ohio | Minimum
Commitments and Contingencies
Cost-reimbursement at risk					$ 146,000,000

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