Fair Value Measures - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) property	Jun. 30, 2016 USD ($) property
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties impaired | property	38	132
Impairment charges	$ 24,494	$ 169,300
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	7.40%
Capitalization rates	6.90%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	7.80%
Capitalization rates	10.00%
Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	7.50%
Capitalization rates	8.80%
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of real estate assets deemed to be impaired	$ 50,000	472,600
Carrying value of real estate assets deemed to be impaired	$ 74,500	$ 641,900