SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Carrying cost
Balance at beginning of period	$ 1,421,456	$ 1,392,122	$ 1,301,563
Acquisitions	58,414	40,408	82,405
Improvements	23,363	38,528	25,800
Capitalized interest	608	1,248	908
Cost of real estate sold	(19,270)	(50,850)	(18,554)
Ending balance	1,484,571	1,421,456	1,392,122
Accumulated depreciation
Balance at beginning of period	314,875	306,033	275,861
Depreciation expense	39,094	37,416	37,492
Cost of real estate sold	(6,214)	(28,574)	(7,320)
Ending balance	$ 347,755	$ 314,875	$ 306,033