DISCONTINUED OPERATIONS (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business					$ (857)	$ 103,407	$ 0
Impairment of assets of discontinued operations					0	23,365	169,002
Natural Gas Storage
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business	$ 102,600
Working capital adjustments related to sale of businesses	2,400
Impairment of assets of discontinued operations	$ 2,500	$ (5,400)	$ 26,300	$ 169,000		23,400
Results from discontinued operations
Revenue					0	25,862	55,757
Depreciation and amortization					0	0	7,608
Loss from discontinued operations					$ (857)	(59,641)	(187,174)
Natural Gas Storage | Loss from Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of assets of discontinued operations						$ 23,400	$ 169,000