SEGMENT REPORTING - Financial Information Concerning Company's Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 890,144	$ 718,596	$ 2,655,946	$ 2,097,604
Gross Profit	379,260	299,675	1,129,539	885,830
Amortization	33,128	9,239	102,311	26,957	$ 45,498
EBITA	191,713	171,393	564,168	511,690
Other Segments
Segment Reporting Information [Line Items]
Revenues	70,741	75,899	206,886	199,981
Gross Profit	34,499	37,521	102,286	97,213
Amortization	1,962	2,054	5,921	5,665
EBITA	14,238	16,838	43,912	39,888
Reportable Segments
Segment Reporting Information [Line Items]
EBITA	177,475	154,555	520,256	471,802
Reportable Segments | Domestic Regulated and Compliance Services
Segment Reporting Information [Line Items]
Revenues	593,336	447,609	1,764,000	1,313,957
Gross Profit	274,054	203,136	807,029	605,014
Amortization	24,412	3,634	67,498	10,319
EBITA	163,447	132,806	479,327	401,824
Reportable Segments | International Regulated and Compliance Services
Segment Reporting Information [Line Items]
Revenues	226,067	195,088	685,060	583,666
Gross Profit	70,707	59,018	220,224	183,603
Amortization	6,754	3,551	28,892	10,973
EBITA	$ 14,028	$ 21,749	$ 40,929	$ 69,978