REVENUE Disaggregation of Revenue - Geographical (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 2,158,061	$ 1,840,897	$ 6,150,866	$ 5,365,908
U.S.
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,887,263	1,587,510	5,344,372	4,636,878
Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	115,397	111,483	345,805	319,022
Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	80,640	80,432	253,386	235,527
Mexico
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	68,705	53,427	189,181	151,169
Singapore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6,056	8,045	18,122	23,312
FMS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,336,548	1,195,797	3,874,580	3,491,846
FMS | U.S.
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,180,337	1,041,610	3,395,291	3,048,742
FMS | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	75,571	73,755	225,903	207,577
FMS | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	80,640	80,432	253,386	235,527
FMS | Mexico
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
FMS | Singapore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
DTS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	340,604	272,201	970,196	811,277
DTS | U.S.
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	340,604	272,201	970,196	811,277
DTS | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0		0	0
DTS | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
DTS | Mexico
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
DTS | Singapore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
SCS
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	628,544	488,506	1,727,775	1,405,823
SCS | U.S.
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	508,196	384,414	1,384,044	1,106,226
SCS | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	45,587	42,620	136,428	125,116
SCS | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
SCS | Mexico
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	68,705	53,427	189,181	151,169
SCS | Singapore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6,056	8,045	18,122	23,312
Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(147,635)	(115,607)	(421,685)	(343,038)
Eliminations | U.S.
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(141,874)	(110,715)	(405,159)	(329,367)
Eliminations | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(5,761)	(4,892)	(16,526)	(13,671)
Eliminations | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Eliminations | Mexico
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Eliminations | Singapore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 0	$ 0	$ 0	$ 0