Derivative and Other Fair Value Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$ 12,132	$ 1,524
Fair Value Of Serp Investments	78,629	70,655
Other Assets, Fair Value Disclosure	1,675	2,214
Assets, Fair Value Disclosure	92,436	74,393
Derivative liability, fair value	3,456	44,050
Other Liabilities, Fair Value Disclosure	78,629	70,655
Liabilities, Fair Value Disclosure	82,085	114,705
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	376,057	398,372
Fair Value, Inputs, Level 1 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Fair Value Of Serp Investments	78,629	70,655
Other Assets, Fair Value Disclosure	1,675	2,214
Assets, Fair Value Disclosure	80,304	72,869
Derivative liability, fair value	0	0
Other Liabilities, Fair Value Disclosure	78,629	70,655
Liabilities, Fair Value Disclosure	78,629	70,655
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	12,132	1,524
Fair Value Of Serp Investments	0	0
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	12,132	1,524
Derivative liability, fair value	3,456	44,050
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	3,456	44,050
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	376,057	398,372
Fair Value, Inputs, Level 3 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Fair Value Of Serp Investments	0	0
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	0	0
Derivative liability, fair value	0	0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Redeemable Noncontrolling Interest Operating Partnership Liability Fair Value Disclosure	$ 0	$ 0