Redeemable Noncontrolling Interests (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Redeemable Noncontrolling Interest Units Table [Abstract]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount	$ 898,152	$ 934,677
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	46,000	226,000
Redeemable Noncontrolling Interests Rollforward [Abstract]
Reedemable Noncontrolling Interest, Beginning Balance	1,160,677	1,327,974
Net income	(45,263)	(55,912)
Distributions	(54,315)	(50,865)
Conversion of Class A redeemable units into common shares, at redemption value	(89,762)	(64,830)
Adjustment to carry Class A redeemable units at redemption value	52,117	(98,092)
Cumulative Redeemable Preferred Units Redemption Amount	(168,300)	(28,000)
Other, net	(1,528)	18,578
Reedemable Noncontrolling Interest, Ending Balance	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	55,011	54,865
Cumulative Redeemable Preferred Units Redemption Amount	168,300	28,000
Common Class A [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Outstanding Partnership Units held by Third Parties	11,215,682	12,160,771
Preferred Or Annual Distribution Rate (in dollars per share)	$ 2.76
Series D10 Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Dividend Percentage	7.00%
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	0	80,000
Outstanding Partnership Units held by Third Parties	0	3,200,000
Par or Stated Value Per Share	$ 25.00
Preferred Or Annual Distribution Rate (in dollars per share)	$ 1.75
Series D11 Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interests Rollforward [Abstract]
Cumulative Redeemable Preferred Units Redemption Amount	(28,000)
Redeemable Noncontrolling Interests Additional Disclosure [Abstract]
Cumulative Redeemable Preferred Units Redemption Amount	28,000
Series D14 Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Dividend Percentage	6.75%
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	0	100,000
Outstanding Partnership Units held by Third Parties	0	4,000,000
Par or Stated Value Per Share	$ 25.00
Preferred Or Annual Distribution Rate (in dollars per share)	$ 1.6875
Series D15 Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Dividend Percentage	6.875%
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	45,000	45,000
Outstanding Partnership Units held by Third Parties	1,800,000	1,800,000
Par or Stated Value Per Share	$ 25.00
Preferred Or Annual Distribution Rate (in dollars per share)	$ 1.71875
Series D16 Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Dividend Percentage	5.00%
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	$ 1,000	$ 1,000
Outstanding Partnership Units held by Third Parties	1	1
Par or Stated Value Per Share	$ 1,000,000
Preferred Or Annual Distribution Rate (in dollars per share)	$ 50,000
Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interest Units Table [Abstract]
Outstanding Partnership Units held by Third Parties	1,800,001	9,000,001