CHANGE IN ACCOUNTING POLICIES AND ATS ACQUISITION - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract liability		$ 129,560		$ 117,679
Other operating expenses		583,023	$ 608,144
Contract asset		23,682		24,329
Goodwill		$ 8,019,849		8,019,861
Impact of ASC 606 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract liability				6,978
Other operating expenses			(3,417)
Contract asset				24,329
Goodwill				0
ATS Acquisition | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other operating expenses			$ (1,876)
Goodwill				$ 23,101
Installation Services | Impact of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings, net of tax	$ 5,093
Cumulative effect on retained earnings, tax	1,885
Commissions | Impact of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings, net of tax	17,759
Cumulative effect on retained earnings, tax	$ 6,570