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Fair Value of Assets and Liabilities - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Fair value of assets and liabilities
Loss on asset impairment	$ 18,428	$ 1,300	$ 43,736	$ 19,714	$ 43,736
Real estate properties, net	1,633,299			$ 1,633,299		$ 2,101,635
Total rents \| Credit concentration
Fair value of assets and liabilities
Concentration risk, percent				7.50%
Real Estate Held-for-sale
Fair value of assets and liabilities
Loss on asset impairment	18,400
Real Estate Held-for-sale \| Level 2 \| Market Approach Valuation Technique
Fair value of assets and liabilities
Assets, fair value	80,600	23,300		$ 80,600
Fair Value, Measurements, Nonrecurring \| Disposition Plan \| Carrying Amount
Fair value of assets and liabilities
Real estate properties, net	$ 99,000	$ 24,600		$ 99,000