GOODWILL AND OTHER INTANGIBLE ASSETS - Additional Information (Detail) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015 USD ($) Segment	Dec. 31, 2015 USD ($) Segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Intangible Assets by Major Class [Line Items]
Number of geographical reportable segments | Segment		2
Number of reporting units | Segment	3
Goodwill		$ 3,758,177	$ 2,418,832	$ 2,231,582
Assets impairment charges		4,200	9,900
Aggregate amortization expense		45,498	32,692	27,067
Customer relationships
Intangible Assets by Major Class [Line Items]
Assets impairment charges		$ 200
Finite-lived intangible assets, weighted average remaining useful life in years		19 years 2 months 12 days
Customer relationships | Minimum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life		10 years
Customer relationships | Maximum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life		40 years
Tradenames
Intangible Assets by Major Class [Line Items]
Assets impairment charges		$ 1,300
Finite-lived intangible assets, weighted average remaining useful life in years		17 years 2 months 12 days
Tradenames | Minimum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life		15 years
Tradenames | Maximum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life		40 years
Covenants not-to-compete
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, weighted average remaining useful life in years		3 years 8 months 12 days
Covenants not-to-compete | Minimum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life		5 years
Covenants not-to-compete | Maximum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life		14 years
Other intangibles
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, weighted average remaining useful life in years		19 years 1 month 6 days
Operating permits
Intangible Assets by Major Class [Line Items]
Assets impairment charges		$ 2,700
Domestic Regulated and Compliance Services | Income Approach Goodwill Impairment Test
Intangible Assets by Major Class [Line Items]
Percentage of fair value in excess of carrying amount	100.00%
Domestic Regulated Recall and Returns Management Services | Income Approach Goodwill Impairment Test
Intangible Assets by Major Class [Line Items]
Percentage of fair value in excess of carrying amount	100.00%
International Regulated and Compliance Services
Intangible Assets by Major Class [Line Items]
Goodwill	$ 589,300
International Regulated and Compliance Services | Income Approach Goodwill Impairment Test
Intangible Assets by Major Class [Line Items]
Percentage of fair value in excess of carrying amount	88.00%
International
Intangible Assets by Major Class [Line Items]
Goodwill		785,902	$ 580,093	$ 557,772
International | Puerto Rico | Goodwill
Intangible Assets by Major Class [Line Items]
Reclassification of goodwill		$ 4,300