Equity and Capital - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income Loss [Line Items]
Document Fiscal Year Focus			2015
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 2,155	$ 2,260	$ 6,654	$ 7,098
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(11,347)	(23,794)
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			(58,498)	(17,883)
Current period other comprehensive income, net			(4,693)	(16,696)
Ending balance	(63,191)	(34,579)	(63,191)	(34,579)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			6,654	7,098
Partnership Interest [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			(57,748)
Current period other comprehensive income, net	(13,656)	2,504	(4,693)	(16,696)
Ending balance	(62,307)		(62,307)
Partnership Interest [Member] | General Partner [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Current period other comprehensive income, net			0	0
Partnership Interest [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Current period other comprehensive income, net			(4,559)	(16,559)
Controlling [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(11,022)	(28,326)
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			(57,748)	(17,404)
Current period other comprehensive income, net			(4,486)	(21,360)
Ending balance	(62,234)	(38,764)	(62,234)	(38,764)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			6,536	6,966
Controlling [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(73)	4,801
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			0	0
Current period other comprehensive income, net			(73)	4,801
Ending balance	(73)	4,801	(73)	4,801
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			0	0
Controlling [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(11,095)	(23,525)
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			(57,748)	(17,404)
Current period other comprehensive income, net			(4,559)	(16,559)
Ending balance	(62,307)	(33,963)	(62,307)	(33,963)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			6,536	6,966
Noncontrolling Interest [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(252)	(277)
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			(750)	(479)
Current period other comprehensive income, net			(134)	(145)
Ending balance	(884)	(624)	(884)	(624)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			118	132
Noncontrolling Interest [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			0	8
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			0	0
Current period other comprehensive income, net			0	8
Ending balance	0	8	0	8
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			0	0
Noncontrolling Interest [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(252)	(269)
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance			(750)	(479)
Current period other comprehensive income, net			(134)	(137)
Ending balance	$ (884)	$ (616)	(884)	(616)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			$ 118	$ 132