Redeemable Noncontrolling Interests (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended					0 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Common Class A [Member]	Dec. 31, 2012 Common Class A [Member]	May 09, 2013 Series D15 Cumulative Redeemable Preferred Unit [Member]	Dec. 31, 2013 Series D15 Cumulative Redeemable Preferred Unit [Member]	Dec. 31, 2012 Series D15 Cumulative Redeemable Preferred Unit [Member]	Dec. 31, 2013 Series D16 Cumulative Redeemable Preferred Unit [Member]	Dec. 31, 2012 Series D16 Cumulative Redeemable Preferred Unit [Member]	Dec. 31, 2013 Cumulative Redeemable Preferred Unit [Member]	Dec. 31, 2012 Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount	$ 1,002,620	$ 898,152
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	1,000	46,000					0	45,000	1,000	1,000
Outstanding Partnership Units held by Third Parties				11,292,038	11,215,682		0	1,800,000	1	1	1	1,800,001
Par or Stated Value Per Share									$ 1,000,000
Preferred Or Annual Distribution Rate (in dollars per share)				$ 2.92					$ 50,000
Dividend Percentage							6.875%		5.00%
Redeemable Noncontrolling Interests Rollforward [Abstract]
Reedemable Noncontrolling Interest, Beginning Balance	944,152	1,160,677
Net Income	24,817	45,263
Other comprehensive income (loss)	5,296	(6,707)	271
Distributions	(34,053)	(54,315)
Redemption of Class A units for common shares, at redemption value	(25,317)	(89,762)
Adjustment to carry Class A redeemable units at redemption value	108,252	52,117
Cumulative Redeemable Preferred Units Redemption Amount	(36,900)	(168,300)				(36,900)
Other, net	17,373	5,179
Reedemable Noncontrolling Interest, Ending Balance	1,003,620	944,152	1,160,677
Redeemable Noncontrolling Interests Additional Disclosure [Abstract]
Fair value of Series G convertible preferred units and Series D-13 cumulative redeemable preferred units											$ 55,097	$ 55,011