Senior Unsecured Notes and Secured Debt (Details 2) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Secured debt principal activity
Secured debt issued	$ 98,100,000	$ 85,140,000
Secured debt extinguished	286,162,000	575,373,000
Excluding Fair Value Adjustments [Member]
Secured debt principal activity
Secured debt principal balance	2,861,720,000	3,065,923,000	3,010,711,000	2,311,586,000
Secured debt issued	98,100,000	85,140,000
Secured debt assumed	62,505,000	1,241,898,000
Secured debt extinguished	(240,355,000)	(535,367,000)
Secured debt principal payments	(45,807,000)	(40,006,000)
Secured debt foreign currency	$ (23,434,000)	$ 2,672,000
Secured debt principal balance average rate	0.0494	0.0508	0.0509	0.0514
Secured debt principal issued average rate	0.0323	0.0505
Secured debt principal assumed average rate	0.0311	0.0411
Secured debt principal extinguished average rate	0.0566	0.0352
Secured debt principal payment average rate	0.0497	0.0527
Secured debt principal foreign currency average rate	0.0378	0.0404