COMMITMENTS AND CONTINGENCIES (Detail)	Dec. 31, 2017 USD ($) lawsuit	Dec. 31, 2014 lawsuit defendant	Jul. 31, 2007 death
Con Ed Matter [Member]
Commitments and Contingencies Disclosure [Line Items]
Number of deaths | death			1
Number of lawsuits	68
Insurance coverage subject to deductible limit | $	$ 250,000
Delaware Cases
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits		2
Washington Case
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits		1
Subsidiaries
Commitments and Contingencies Disclosure [Line Items]
Number of defendants | defendant		3
Quest Integrity
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits		3