Equity and Capital Equity and Capital - Common Stock (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Aug. 10, 2013 Maximum [Member]	Sep. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2012 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2014 Loss on Settlement of Derivative Instruments [Member]	Dec. 31, 2013 Loss on Settlement of Derivative Instruments [Member]	Sep. 30, 2013 Loss on Settlement of Derivative Instruments [Member]	Dec. 31, 2012 Loss on Settlement of Derivative Instruments [Member]	Sep. 30, 2014 Fair Value of Derivative Instruments [Member]	Dec. 31, 2013 Fair Value of Derivative Instruments [Member]	Sep. 30, 2013 Fair Value of Derivative Instruments [Member]	Dec. 31, 2012 Fair Value of Derivative Instruments [Member]
Class of Stock [Line Items]
Document Fiscal Year Focus			2014
Amount reclassified from accumulated other comprehensive loss	$ (2,217,000)	$ (2,366,000)	$ (6,966,000)	$ (7,098,000)
Shares issued		30	872	1,899
Accumulated other comprehensive loss						(33,963,000)	(17,404,000)	(28,430,000)	(57,715,000)	(45,914,000)	(52,542,000)	(54,905,000)	(61,991,000)	7,150,000	35,138,000	26,475,000	4,276,000
Equity Issuances, Amount Available for Issuance	150,000,000		150,000,000		200,000,000
Weighted Average Price Per Share		$ 52.28	$ 57.35	$ 53.35
Net proceeds from common stock issuance		1,568,000	49,995,000	101,342,000
Payments for Commissions		24,000	695,000	1,520,000
Payments of Stock Issuance Costs			$ 0	$ 69,000