BUSINESS COMBINATIONS (2012 Acquisitions) (Details) (USD $)	0 Months Ended	12 Months Ended
	Dec. 28, 2012	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 07, 2012
Summary of recognized assets acquired and liabilities assumed
Goodwill		$ 579,715,000	$ 452,669,000	$ 570,960,000
Oil Re-refining and Recycling
Summary of recognized assets acquired and liabilities assumed
Goodwill	173,200,000		50,883,000	171,161,000
SK Environmental Services
Summary of recognized assets acquired and liabilities assumed
Goodwill	174,100,000		173,873,000	172,309,000
Industrial and Field Services
Summary of recognized assets acquired and liabilities assumed
Goodwill	75,400,000		109,214,000	109,873,000
Safety-Kleen
Business Acquisition [Line Items]
Outstanding common shares acquired (as a percent)	100.00%
Cash paid for peak common shares	305,000,000
Issuance of acquisition-related common stock, net	369,300,000
Stock issued during period, shares, acquisitions	6,900,000.0
Proceeds from issuance of private placement	589,000,000
Business acquisition, cost of acquired entity, transaction costs		6,300,000		2,700,000
Summary of recognized assets acquired and liabilities assumed
Inventories and supplies	107,376,000
Other current assets	155,674,000
Property, plant and equipment	516,002,000
Permits and other intangibles	438,627,000
Other assets	4,338,000
Current liabilities	(206,241,000)
Closure and post-closure liabilities	(7,553,000)
Remedial liabilities, less current portion	(48,301,000)
Other long-term liabilities	(119,331,000)
Total identifiable net assets	840,591,000
Goodwill	422,693,000
Total	1,263,284,000
Business combination, acquired receivables, fair value	137,600,000
Customer receivables, gross amount due	142,700,000
Business Acquisition, Pro Forma Information
Pro forma combined revenues		3,529,592,000
Pro forma combined net income		125,425,000
Safety-Kleen | Senior secured notes | Unsecured senior notes 2021
Business Acquisition [Line Items]
Long-term debt, gross	600,000,000
Senior secured notes, interest rate (as a percent)	5.125%				5.125%
Safety-Kleen | Preliminary allocations
Summary of recognized assets acquired and liabilities assumed
Inventories and supplies	102,339,000
Other current assets	152,245,000
Property, plant and equipment	514,712,000
Permits and other intangibles	421,400,000
Other assets	4,985,000
Current liabilities	(192,652,000)
Closure and post-closure liabilities	(15,774,000)
Remedial liabilities, less current portion	(38,370,000)
Other long-term liabilities	(128,375,000)
Total identifiable net assets	820,510,000
Goodwill	436,749,000
Total	1,257,259,000
Safety-Kleen | Measurement Period Adjustments
Summary of recognized assets acquired and liabilities assumed
Inventories and supplies	5,037,000
Other current assets	3,429,000
Property, plant and equipment	1,290,000
Permits and other intangibles	17,227,000
Other assets	(647,000)
Current liabilities	(13,589,000)
Closure and post-closure liabilities	8,221,000
Remedial liabilities, less current portion	(9,931,000)
Other long-term liabilities	9,044,000
Total identifiable net assets	20,081,000
Goodwill	(14,056,000)
Total	6,025,000
Other 2012 Acquisitions
Summary of recognized assets acquired and liabilities assumed
Total		108,900,000
Business Acquisition, Pro Forma Information
Pro forma combined revenues		2,268,621,000
Pro forma combined net income		130,322,000
Number of businesses acquired		3
Assumed debt		7,700,000
Post-closing adjustments		2,100,000
Acquisition related costs		$ 400,000