Redeemable Partnership Units (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Redeemable Noncontrolling Interests Rollforward [Abstract]
Reedemable Noncontrolling Interest, Beginning Balance	$ 1,003,620	$ 944,152
Net Income	3,860	14,719
Other comprehensive income	361	8,299
Distributions	(8,383)	(8,946)
Redemption of Class A units, at redemption value	(5,156)	(13,404)
Adjustment to carry Class A redeemable units at redemption value	136,937	44,998
Other, net	9,592	5,264
Reedemable Noncontrolling Interest, Ending Balance	1,140,831	995,082
Redeemable Noncontrolling Interests Additional Disclosure [Abstract]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount	1,139,831		1,002,620
Capital Unit, Class A [Member]
Redeemable Noncontrolling Interests Additional Disclosure [Abstract]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount	1,139,831		1,002,620
Cumulative Redeemable Preferred Unit [Member]
Redeemable Noncontrolling Interests Additional Disclosure [Abstract]
Fair value of Series G convertible preferred units and Series D-13 cumulative redeemable preferred units	$ 55,097		$ 55,097