Segment Information - Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($) segment	Dec. 31, 2013 segment
Segment Information
Number of activity segments | segment	48
Reconciliation of assets from segment to consolidated
Net real estate	$ 10,618,884	$ 9,781,540
Goodwill	15,321	15,470
Other corporate assets	197,248	175,888
Total assets	11,865,870	11,012,622
Apparel
Reconciliation of assets from segment to consolidated
Net real estate	180,175	185,237
Intangible assets	48,116	52,444
Automotive service
Reconciliation of assets from segment to consolidated
Net real estate	129,328	120,660
Intangible assets	19,131	2,909
Goodwill	448	451
Automotive tire services
Reconciliation of assets from segment to consolidated
Net real estate	247,200	255,447
Intangible assets	13,202	14,871
Goodwill	865	865
Beverages
Reconciliation of assets from segment to consolidated
Net real estate	297,724	302,001
Intangible assets	2,538	2,797
Child care
Reconciliation of assets from segment to consolidated
Net real estate	52,392	54,194
Goodwill	5,034	5,095
Convenience stores
Reconciliation of assets from segment to consolidated
Net real estate	724,972	752,047
Intangible assets	16,040	17,535
Goodwill	2,009	2,023
Dollar stores
Reconciliation of assets from segment to consolidated
Net real estate	1,158,948	1,165,560
Intangible assets	56,420	58,691
Drug stores
Reconciliation of assets from segment to consolidated
Net real estate	1,384,506	1,036,697
Intangible assets	189,433	194,905
Financial services
Reconciliation of assets from segment to consolidated
Net real estate	254,022	262,095
Intangible assets	34,626	39,564
Grocery stores
Reconciliation of assets from segment to consolidated
Net real estate	331,565	341,773
Intangible assets	42,823	46,964
Health and fitness
Reconciliation of assets from segment to consolidated
Net real estate	839,872	546,583
Intangible assets	65,037	66,460
Health care
Reconciliation of assets from segment to consolidated
Net real estate	220,018	227,084
Intangible assets	29,950	35,017
Home improvement
Reconciliation of assets from segment to consolidated
Net real estate	268,974	227,733
Intangible assets	42,630	35,726
Restaurants - casual dining
Reconciliation of assets from segment to consolidated
Net real estate	419,455	449,211
Intangible assets	9,392	10,649
Goodwill	2,215	2,279
Restaurants - quick service
Reconciliation of assets from segment to consolidated
Net real estate	467,643	336,753
Intangible assets	32,612	16,415
Goodwill	1,082	1,085
Theaters
Reconciliation of assets from segment to consolidated
Net real estate	371,617	375,982
Intangible assets	17,673	21,601
Transportation services
Reconciliation of assets from segment to consolidated
Net real estate	686,041	661,053
Intangible assets	92,602	101,040
Wholesale clubs
Reconciliation of assets from segment to consolidated
Net real estate	452,563	465,569
Intangible assets	36,215	39,707
Other non-reportable segments
Reconciliation of assets from segment to consolidated
Net real estate	2,131,869	2,015,861
Intangible assets	285,977	282,429
Goodwill	$ 3,668	$ 3,672
Number of non-reportable segments | segment		30	30