ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) - Schedule of Changes in AOCI By Component (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 11,086,242	$ 10,711,734
OCI Before Reclassifications		(7,600)
Amounts Reclassified from AOCI		6,500
Net OCI		(1,100)
Ending balance	11,486,817	11,086,242
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(66,403)	(65,282)
OCI Before Reclassifications	(200)
Amounts Reclassified from AOCI	6,600
Net OCI	6,400
Ending balance	(60,000)	(66,403)
Qualified Cash Flow Hedging Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(6,200)	(8,200)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	1,800	2,000
Net OCI	1,800	2,000
Ending balance	(4,400)	(6,200)
Unrealized Losses on Marketable Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	0	400
OCI Before Reclassifications	(500)	(400)
Amounts Reclassified from AOCI	0	0
Net OCI	(500)	(400)
Ending balance	(500)	0
Defined Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(60,200)	(57,500)
OCI Before Reclassifications	300	(7,200)
Amounts Reclassified from AOCI	4,800	4,500
Net OCI	5,100	(2,700)
Ending balance	$ (55,100)	$ (60,200)

Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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