GOODWILL AND OTHER INTANGIBLE ASSETS - Values of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	$ 2,011,351	$ 1,993,586
Accumulated Amortization	170,507	151,025
Net Value	1,840,844	1,842,561	$ 909,645
Operating permits
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	234,888	233,101
Net Value	234,888	233,101
Tradenames
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	428,282	426,498
Net Value	428,282	426,498
Customer relationships
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	1,319,782	1,304,388
Accumulated Amortization	162,831	144,020
Net Value	1,156,951	1,160,368
Covenants not-to-compete
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	7,630	6,878
Accumulated Amortization	5,340	5,141
Net Value	2,290	1,737
Tradenames
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	3,935	3,819
Accumulated Amortization	1,022	948
Net Value	2,913	2,871
Other
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	16,834	18,902
Accumulated Amortization	1,314	916
Net Value	$ 15,520	$ 17,986