SEGMENT REPORTING - Financial Information Concerning Company's Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 906,396	$ 890,144	$ 891,621	$ 874,181	$ 888,304	$ 718,596	$ 715,689	$ 663,319	$ 3,562,342	$ 2,985,908	$ 2,555,601
Gross Profit	372,415	379,260	381,095	369,184	380,355	299,675	304,824	281,331	1,501,954	1,266,185	1,094,411
Amortization	26,989	$ 33,128	$ 50,909	$ 18,274	18,541	$ 9,239	$ 8,921	$ 8,797	129,300	45,498	32,692
EBITA									727,624	707,477	648,015
Total Assets	6,980,061				7,065,163				6,980,061	7,065,163	4,373,302
Domestic and Canada RCS
Segment Reporting Information [Line Items]
Revenues									2,508,865	1,999,196	1,667,353
Gross Profit									1,124,815	912,220	772,518
Amortization									95,640	22,714	12,728
EBITA									688,161	631,395	594,204
Total Assets	5,094,107				4,913,485				5,094,107	4,913,485	2,616,751
International Regulated and Compliance Services
Segment Reporting Information [Line Items]
Revenues									751,677	716,771	663,889
Gross Profit									228,484	230,323	216,377
Amortization									25,730	14,926	13,298
EBITA									58,027	89,064	98,494
Total Assets	1,357,047				1,636,382				1,357,047	1,636,382	1,291,671
All Other Segments
Segment Reporting Information [Line Items]
Revenues									301,800	269,941	224,359
Gross Profit									148,655	123,642	105,516
Amortization									7,930	7,858	6,666
EBITA									(18,564)	(12,982)	(44,683)
Total Assets	$ 528,907				$ 515,296				$ 528,907	$ 515,296	$ 464,880