CONTINGENCIES AND COMMITMENTS (Detail) - USD ($)	Oct. 10, 2013	Jun. 30, 2017	Mar. 29, 2017	Dec. 31, 2016
Standby Letters Of Credit [Member]
Loss Contingencies [Line Items]
Letters of credit, outstanding		$ 48,800,000		$ 47,200,000
FinancialStandbyLetterOfCreditMember
Loss Contingencies [Line Items]
Letters of credit, outstanding		13,900,000		$ 12,800,000
Failure to Meet Contractual Obligations [Member]
Loss Contingencies [Line Items]
Damages sought	$ 25,000,000
Surety Bond [Member]
Loss Contingencies [Line Items]
Surety Bond Outstanding		56,000,000
Damage from Fire, Explosion or Other Hazard [Member]
Loss Contingencies [Line Items]
Estimated Litigation Liability		1,000,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Range of possible loss		0
Maximum [Member]
Loss Contingencies [Line Items]
Range of possible loss		56,000,000
Westinghouse Electric Company (WEC) [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Debtor-in-Possession Financing, Amount Arranged			$ 800,000,000
AP1000 US [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Range of possible loss		0
AP1000 US [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Range of possible loss		$ 31,000,000
Westinghouse Electric Company (WEC) [Member] | Collectibility of Receivables [Member]
Loss Contingencies [Line Items]
Range of possible loss			$ 6,500,000