Redeemable Paternership Units (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Redeemable Partnership Units Table [Abstract]
Redeemable Partnership Units, Equity, Common, Carrying Amount	$ 1,172,256		$ 1,223,793
Redeemable Partnership Units Rollforward [Abstract]
Balance at January 1	1,229,221	$ 1,337,780
Net income (loss)	(7,487)	5,287
Other comprehensive income (loss)	427	(1,288)
Distributions	(7,835)	(7,280)
Other, net	14,364	19,133
Balance at March 31	1,177,684	1,304,790
Capital Unit Class A [Member]
Redeemable Partnership Units Table [Abstract]
Redeemable Partnership Units, Equity, Common, Carrying Amount	1,172,256		1,223,793
Redeemable Partnership Units Rollforward [Abstract]
Redemption of Class A units, at redemption value	(14,482)	(23,493)
Adjustments to carry redeemable Class A units at redemption value	(36,524)	$ (25,349)
Cumulative Redeemable Preferred Unit [Member]
Redeemable Partnership Units Additional Disclosure [Abstract]
Fair value of Series G convertible preferred units and Series D-13 cumulative redeemable preferred units	$ 50,561		$ 50,561