CONTINGENCIES AND COMMITMENTS (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Jan. 04, 2018	Oct. 31, 2017	Dec. 31, 2017	Mar. 29, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Asset Retirement Obligation			$ 7,400,000
Surety Bond Outstanding			56,000,000
Loss Contingency, Damages Sought, Value			1,000,000,000
Loss Contingency, Actions Taken by Plaintiff		$ 400,000,000
Standby letters of credit
Loss Contingencies [Line Items]
Letters of credit			21,300,000		$ 47,200,000
Financial Standby Letter of Credit [Member]
Loss Contingencies [Line Items]
Letters of credit			14,600,000		$ 12,800,000
Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value			25,000,000
Minimum [Member] | Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum			0
Maximum [Member] | Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum			55,500,000
Pending Litigation [Member] | Westinghouse Electric Company (WEC) [Member]
Loss Contingencies [Line Items]
Debtor-in-Possession Financing, Amount Arranged				$ 800,000,000
AP1000 US [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum			0
AP1000 US [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum			$ 31,000,000
Westinghouse Electric Company (WEC) [Member] | Collectibility of Receivables [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum				$ 4,900,000
Westinghouse Electric Company (WEC) [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Business Combination, Consideration Transferred	$ 4,600,000,000