Fair Value Measures (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) property	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) property	Jun. 30, 2014 USD ($)	Dec. 31, 2014 property
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairments	$ 85,341	$ 1,556	$ 85,341	$ 1,556
Number of properties with carrying amounts in excess of undiscounted cash flows | property			27
Number of properties noted to have estimated sales price less than carrying amount | property			161
Number of properties classified held for sale | property	2		2		2
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Length of time for properties more likely than not of being disposed			12 months
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Length of time for properties more likely than not of being disposed			24 months
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate assets carrying values			$ 319,300	3,200
Estimated fair value due to reduction from impairment charges	$ 234,000	$ 1,600	$ 234,000	$ 1,600