GOODWILL AND OTHER INTANGIBLE ASSETS - Values of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	$ 2,179,699	$ 1,993,586
Accumulated Amortization	252,590	151,025
Net Value	1,927,109	1,842,561	$ 909,645
Operating permits
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	242,281	233,101
Net Value	242,281	233,101
Tradenames
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	318,776	426,498
Net Value	318,776	426,498
Customer relationships
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	1,579,988	1,304,388
Accumulated Amortization	241,368	144,020
Net Value	1,338,620	1,160,368
Covenants not-to-compete
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	10,561	6,878
Accumulated Amortization	6,501	5,141
Net Value	4,060	1,737
Tradenames
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	9,088	3,819
Accumulated Amortization	1,797	948
Net Value	7,291	2,871
Other
Intangible Assets By Major Class [Line Items]
Gross Carrying Amount	19,005	18,902
Accumulated Amortization	2,924	916
Net Value	$ 16,081	$ 17,986