Fair Value of Financial Instruments Fair Value of Financial Instruments (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013 property	Dec. 31, 2014 property	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of impaired properties		2	16
Impairments	$ 96,700,000		$ 100,547,000	$ 3,346,000
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate impaired		4,500,000	199,500,000
Fair value of impaired real estate assets	$ 99,000,000	1,200,000	$ 99,000,000	$ 1,200,000