Segments - Reconciliation of Net Operating Income to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net operating income	$ 19,740	$ 18,393	$ 17,973	$ 17,371	$ 15,819	$ 16,488	$ 15,101	$ 12,702	$ 26,679	$ 26,584	$ 21,379
Depreciation and amortization									(35,328)	(23,153)	(17,569)
General and administrative expenses									(9,552)	(8,397)	(7,711)
Acquisition, development and other pursuit costs									(1,563)	(1,935)	(229)
Impairment charges									(355)	(41)	(15)
Interest income									3,228	126	0
Interest expense									(16,466)	(13,333)	(10,648)
Loss on extinguishment of debt									(82)	(512)	0
Change in fair value of interest rate derivatives									(941)	(229)	(233)
Other income									147	119	120
Income tax benefit (provision)									(343)	34	(70)
Net income									42,755	31,183	12,759
Operating Segments
Net operating income									73,477	60,110	46,903
Segment Reconciling Items
Depreciation and amortization									(35,328)	(23,153)	(17,569)
General and administrative expenses									(9,552)	(8,397)	(7,711)
Acquisition, development and other pursuit costs									(1,563)	(1,935)	(229)
Impairment charges									(355)	(41)	(15)
Interest income									3,228	126	0
Interest expense									(16,466)	(13,333)	(10,648)
Loss on extinguishment of debt									(82)	(512)	0
Gain on real estate dispositions									30,533	18,394	2,211
Change in fair value of interest rate derivatives									(941)	(229)	(233)
Other income									147	119	120
Income tax benefit (provision)									$ (343)	$ 34	$ (70)