Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		$ 3,148,366
Ending Balance		3,289,584
Total accumulated other comprehensive loss		3,148,366		$ 3,289,584	$ 3,148,366
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				3,225,100	3,087,358
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(38,701)	$ (56,767)
Unrealized income (loss)		(9,221)	16,314
Ending Balance		(47,922)	(40,453)
Total accumulated other comprehensive loss		(38,701)	(56,767)	(47,922)	(38,701)	$ (40,453)
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		150	(455)
Unrealized income (loss)		620	(25)
Reclassification adjustment	[1]	(127)	391
Ending Balance		643	(89)
Total accumulated other comprehensive loss		150	(455)	643	150	(89)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		(47,279)	(40,542)
Total accumulated other comprehensive loss		(47,279)	(40,542)	(47,279)		(40,542)
AOCI Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		957	801
Total accumulated other comprehensive loss		957	$ 801	957		801
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(37,797)
Ending Balance		(46,322)
Total accumulated other comprehensive loss		$ (37,797)		(46,322)	$ (37,797)
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				$ (46,322)		$ (39,741)

[1] Amounts reclassified out of Accumulated Other Comprehensive Loss/General & Limited Partner's Equity into contractual interest expense.