Segment Information - Rental Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment revenue information
Rental revenue	$ 1,057,413	$ 976,865	$ 893,457
Tenant reimbursements	43,104	42,015	37,118
Other revenue	2,655	4,405	2,930
Total revenue	1,103,172	1,023,285	933,505
Apparel stores
Segment revenue information
Rental revenue	19,975	19,819	17,674
Automotive service
Segment revenue information
Rental revenue	20,212	18,632	16,548
Automotive tire services
Segment revenue information
Rental revenue	28,754	28,627	28,222
Beverages
Segment revenue information
Rental revenue	27,587	25,451	25,147
Child care
Segment revenue information
Rental revenue	19,712	19,949	20,022
Convenience stores
Segment revenue information
Rental revenue	91,784	90,093	89,754
Dollar stores
Segment revenue information
Rental revenue	90,746	88,126	85,049
Drug stores
Segment revenue information
Rental revenue	117,758	103,324	84,625
Financial services
Segment revenue information
Rental revenue	18,769	17,044	16,828
General merchandise
Segment revenue information
Rental revenue	18,976	16,411	13,550
Grocery stores
Segment revenue information
Rental revenue	32,815	29,506	27,270
Health and fitness
Segment revenue information
Rental revenue	85,901	75,881	62,086
Health care
Segment revenue information
Rental revenue	16,168	16,057	16,039
Home improvement
Segment revenue information
Rental revenue	25,695	23,112	15,593
Motor vehicle dealerships
Segment revenue information
Rental revenue	20,329	15,332	13,909
Restaurants - casual dining
Segment revenue information
Rental revenue	42,312	37,645	38,473
Restaurants - quick service
Segment revenue information
Rental revenue	52,674	41,407	33,388
Theaters
Segment revenue information
Rental revenue	51,926	49,456	47,102
Transportation services
Segment revenue information
Rental revenue	57,694	51,745	46,287
Wholesale clubs
Segment revenue information
Rental revenue	37,531	37,391	36,588
Other
Segment revenue information
Rental revenue	$ 180,095	$ 171,857	$ 159,303