Segment Information - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment revenue information
Rental revenue	$ 265,332	$ 247,578	$ 782,189	$ 724,131
Tenant reimbursements	11,524	10,187	31,741	31,757
Other revenue	318	1,124	1,399	3,729
Total revenue	277,174	258,889	815,329	759,617
Apparel
Segment revenue information
Rental revenue	5,106	4,961	14,860	14,824
Automotive service
Segment revenue information
Rental revenue	5,322	4,690	14,814	13,806
Automotive tire services
Segment revenue information
Rental revenue	7,135	7,132	21,618	21,503
Beverages
Segment revenue information
Rental revenue	7,027	6,397	19,836	19,053
Child care
Segment revenue information
Rental revenue	4,909	5,030	14,846	14,914
Convenience stores
Segment revenue information
Rental revenue	22,757	22,608	68,410	67,681
Dollar stores
Segment revenue information
Rental revenue	22,652	22,086	67,975	65,976
Drug stores
Segment revenue information
Rental revenue	29,230	27,349	86,288	75,832
Financial services
Segment revenue information
Rental revenue	4,267	4,259	12,832	12,787
General merchandise
Segment revenue information
Rental revenue	5,149	4,169	13,702	12,034
Grocery stores
Segment revenue information
Rental revenue	8,331	7,501	23,452	22,504
Health and fitness
Segment revenue information
Rental revenue	21,444	21,238	64,293	54,648
Health care
Segment revenue information
Rental revenue	4,051	4,012	12,116	12,044
Home improvement
Segment revenue information
Rental revenue	6,732	6,155	18,884	16,839
Motor vehicle dealerships
Segment revenue information
Rental revenue	5,215	3,525	15,025	11,285
Restaurants - casual dining
Segment revenue information
Rental revenue	10,951	9,376	31,364	28,119
Restaurants - quick service
Segment revenue information
Rental revenue	13,056	9,956	38,329	29,985
Theaters
Segment revenue information
Rental revenue	12,689	12,288	38,846	36,764
Transportation services
Segment revenue information
Rental revenue	15,196	12,573	42,038	37,775
Wholesale clubs
Segment revenue information
Rental revenue	9,368	9,341	28,107	28,024
Other non-reportable segments
Segment revenue information
Rental revenue	$ 44,745	$ 42,932	$ 134,554	$ 127,734