ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Schedule of Changes in AOCI By Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 11,486,817	$ 11,086,242
OCI Before Reclassifications	(12,100)	(200)
Amounts Reclassified from AOCI	7,000	6,600
Net OCI	(5,100)	6,400
Ending balance	12,629,994	11,486,817
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(60,000)	(66,403)
Ending balance	(65,059)	(60,000)
Qualified Cash Flow Hedging Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4,400)	(6,200)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	1,400	1,800
Net OCI	1,400	1,800
Ending balance	(3,000)	(4,400)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(500)	0
OCI Before Reclassifications	1,200	(500)
Amounts Reclassified from AOCI	0	0
Net OCI	1,200	(500)
Ending balance	700	(500)
Defined Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(55,100)	(60,200)
OCI Before Reclassifications	(13,300)	300
Amounts Reclassified from AOCI	5,600	4,800
Net OCI	(7,700)	5,100
Ending balance	$ (62,800)	$ (55,100)