Equity and Capital - Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income Loss [Roll Forward]
Net gain on cash flow derivative instruments	$ 3,372	$ 34
Amortization of loss on derivative instruments	2,367	2,364
Loss on Settlement of Derivative Instruments [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance at December 31, 2012	(61,991)
Net gain on cash flow derivative instruments	0
Amortization of loss on derivative instruments	(2,362)
Current period other comprehensive income, net	2,362
Ending balance at March 31, 2013	(59,629)
Fair Value of Derivative Instruments [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance at December 31, 2012	4,276
Net gain on cash flow derivative instruments	3,366
Amortization of loss on derivative instruments	(4)
Current period other comprehensive income, net	3,370
Ending balance at March 31, 2013	7,646
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Roll Forward]
Beginning balance at December 31, 2012	(57,715)
Net gain on cash flow derivative instruments	3,366
Amortization of loss on derivative instruments	(2,366)
Current period other comprehensive income, net	5,732
Ending balance at March 31, 2013	$ (51,983)