Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		$ 3,009,947
Ending Balance		2,961,848
Total accumulated other comprehensive loss		3,009,947		$ 2,961,848	$ 3,009,947
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				2,905,266	2,952,928
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		(17,256)	$ (5,823)
Unrealized loss		(5,087)	(10,410)
Ending Balance		(22,343)	(16,233)
Total accumulated other comprehensive loss		(17,256)	(5,823)	(22,343)	(17,256)	$ (16,233)
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		(865)	(377)
Unrealized loss		(1,643)	(1,299)
Reclassification adjustment	[1]	283	352
Ending Balance		(2,225)	(1,324)
Total accumulated other comprehensive loss		(865)	(377)	(2,225)	(865)	(1,324)
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		(24,568)	(17,557)
Total accumulated other comprehensive loss		(24,568)	(17,557)	(24,568)		(17,557)
AOCI Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Ending Balance		380	211
Total accumulated other comprehensive loss		380	$ 211	380		211
AOCI Attributable to Parent [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(17,893)
Ending Balance		(24,188)
Total accumulated other comprehensive loss		$ (17,893)		(24,188)	$ (17,893)
Total accumulated other comprehensive loss included in shareholders' equity/owners' equity				$ (24,188)		$ (17,346)

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