Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		$ 3,148,366
Ending Balance		3,248,288
Total accumulated other comprehensive loss		3,148,366		$ 3,248,288	$ 3,148,366
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				3,185,251	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)		7,932	3,177
Ending Balance		(30,769)	(53,590)
Total accumulated other comprehensive loss		(38,701)	(56,767)	(30,769)	(38,701)	$ (53,590)
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)		369	127
Reclassification adjustment	[1]	16	186
Ending Balance		535	(142)
Total accumulated other comprehensive loss		150	(455)	535	150	(142)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		(30,234)	(53,732)
Total accumulated other comprehensive loss		(30,234)	(53,732)	(30,234)		(53,732)
AOCI Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		560	1,110
Total accumulated other comprehensive loss		560	$ 1,110	560		1,110
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(37,797)
Ending Balance		(29,674)
Total accumulated other comprehensive loss		$ (37,797)		(29,674)	$ (37,797)
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				$ (29,674)		$ (52,622)

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