Impairment Loss on Real Estate Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	$ 8,953	$ 0	$ 46,461
Capitalization
Impaired Long-Lived Assets Held and Used [Line Items]
Loss on impairment, measurement input	14.00%
Estimated Selling Costs
Impaired Long-Lived Assets Held and Used [Line Items]
Loss on impairment, measurement input	0.75%
Disposal Group, Held-for-sale, Not Discontinued Operations | The Dupree
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	$ 1,953	0	0
Disposal Group, Held-for-sale, Not Discontinued Operations | 600 Corporate Drive
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	7,000	0	0
Disposal Group, Held-for-sale, Not Discontinued Operations | Disposal Group of 13 Assets
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment loss on real estate assets	$ 0	$ 0	$ 46,461