Segment Information - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment revenue information
Rental revenue	$ 293,455	$ 265,332	$ 867,325	$ 782,189
Tenant reimbursements	11,933	11,524	34,918	31,741
Other revenue	1,532	318	2,872	1,399
Total revenue	306,920	277,174	905,115	815,329
Apparel
Segment revenue information
Rental revenue	4,718	5,106	14,613	14,860
Automotive service
Segment revenue information
Rental revenue	6,416	5,322	18,257	14,814
Automotive tire services
Segment revenue information
Rental revenue	7,383	7,135	22,158	21,618
Beverages
Segment revenue information
Rental revenue	7,829	7,027	23,345	19,836
Child care
Segment revenue information
Rental revenue	5,062	4,909	15,395	14,846
Convenience stores
Segment revenue information
Rental revenue	27,874	22,757	83,143	68,410
Dollar stores
Segment revenue information
Rental revenue	22,738	22,652	68,246	67,975
Drug stores
Segment revenue information
Rental revenue	31,635	29,230	94,880	86,288
Financial services
Segment revenue information
Rental revenue	7,058	4,267	21,377	12,832
General merchandise
Segment revenue information
Rental revenue	6,296	5,149	17,263	13,702
Grocery stores
Segment revenue information
Rental revenue	13,450	8,331	37,209	23,452
Health and fitness
Segment revenue information
Rental revenue	22,416	21,444	65,810	64,293
Home improvement
Segment revenue information
Rental revenue	7,816	6,732	21,826	18,884
Motor vehicle dealerships
Segment revenue information
Rental revenue	5,749	5,215	18,240	15,025
Restaurants-casual dining
Segment revenue information
Rental revenue	11,073	10,951	32,853	31,364
Restaurants-quick service
Segment revenue information
Rental revenue	14,659	13,056	43,337	38,329
Theaters
Segment revenue information
Rental revenue	14,947	12,689	41,405	38,846
Transportation services
Segment revenue information
Rental revenue	15,635	15,196	46,656	42,038
Wholesale club
Segment revenue information
Rental revenue	9,414	9,368	28,241	28,107
Other non-reportable segments
Segment revenue information
Rental revenue	$ 51,287	$ 48,796	$ 153,071	$ 146,670