Equity (Movement in AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 8,638,814	$ 8,582,264	$ 8,425,809
Net change in fair value of derivatives, net of tax	(14,559)	14,918	5,990
Actuarial gain on pension obligations, net of tax	(1,539)	1,125	(1,452)
Ending balance	8,880,614	8,638,814	8,582,264
Accumulated other comprehensive loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	14,274	(1,769)	(6,307)
Total other comprehensive income	(16,098)	16,043
Ending balance	(1,824)	14,274	(1,769)
Net change in fair value of derivatives
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	20,890	5,972
Net change in fair value of derivatives, net of tax	(14,559)	14,918
Ending balance	6,331	20,890	5,972
Actuarial gain (loss) on pension obligations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(6,616)	(7,741)
Actuarial gain on pension obligations, net of tax	(1,539)	1,125
Ending balance	$ (8,155)	$ (6,616)	$ (7,741)

Amount, after tax, of gain (loss) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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