REVENUES (Tables)

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table presents the Company’s revenues disaggregated by revenue source (in thousands):

	For the Three Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	408,127	$	306,059	$	363	$	714,549
Canada	111,789		22,656		146		134,591
	519,916		328,715		509		849,140
Sources of Revenue (1)
Technical Services	257,006		—		—		$	257,006
Field and Emergency Response Services	76,092		—		—		76,092
Industrial Services	161,046		—		—		161,046
Oil, Gas and Lodging Services and Other	25,772		—		509		26,281
Safety-Kleen Environmental Services	—		200,034		—		200,034
Kleen Performance Products	—		128,681		—		128,681
Total third party revenues	$	519,916	$	328,715	$	509	$	849,140

	For the Three Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	343,323	$	280,617	$	155	$	624,095
Canada	106,308		22,339		46		128,693
	449,631		302,956		201		752,788
Sources of Revenue (1)
Technical Services	254,487		—		—		254,487
Field and Emergency Response Services	70,707		—		—		70,707
Industrial Services	99,733		—		—		99,733
Oil, Gas and Lodging Services and Other	24,704		—		201		24,905
Safety-Kleen Environmental Services	—		192,817		—		192,817
Kleen Performance Products	—		110,139		—		110,139
Total third party revenues	$	449,631	$	302,956	$	201	$	752,788

	For the Six Months Ended June 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	752,099	$	593,701	$	508	$	1,346,308
Canada	207,505		44,932		173		252,610
	959,604		638,633		681		1,598,918
Sources of Revenue (1)
Technical Services	493,312		—		—		493,312
Field and Emergency Response Services	146,027		—		—		146,027
Industrial Services	264,809		—		—		264,809
Oil, Gas and Lodging Services and Other	55,456		—		681		56,137
Safety-Kleen Environmental Services	—		394,195		—		394,195
Kleen Performance Products	—		244,438		—		244,438
Total third party revenues	$	959,604	$	638,633	$	681	$	1,598,918

	For the Six Months Ended June 30, 2017
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	657,106	$	552,688	$	288	$	1,210,082
Canada	188,432		43,169		46		231,647
	845,538		595,857		334		1,441,729
Sources of Revenue (1)
Technical Services	484,705		—		—		484,705
Field and Emergency Response Services	131,726		—		—		131,726
Industrial Services	174,801		—		—		174,801
Oil, Gas and Lodging Services and Other	54,306		—		334		54,640
Safety-Kleen Environmental Services	—		384,544		—		384,544
Kleen Performance Products	—		211,313		—		211,313
Total third party revenues	$	845,538	$	595,857	$	334	$	1,441,729

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1. All revenue except Kleen Performance Products and product sales within Safety-Kleen Environmental Services, including allied products and direct blended oil sales, are recognized over time. Kleen Performance Products and Safety-Kleen Environmental Services product revenues are recognized at a point in time.

Contract Balances

Contract Balances

	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Receivables	$	590,580	$	528,924	$	512,375	$	496,226
Contract Assets (Unbilled Receivables)	62,762		35,922		46,576		36,190
Contract Liabilities (Deferred Revenue)	68,705		67,822		72,089		64,397