Segment Information - Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 segment
Reconciliation of assets from segment to consolidated
Number of activity segments | segment	47
Net real estate	$ 11,903,791	$ 10,618,884
Goodwill	15,067	15,321
Other corporate assets	151,693	176,757
Total assets	13,152,871	11,845,379
Apparel stores
Reconciliation of assets from segment to consolidated
Net real estate	175,418	180,175
Intangible assets	43,786	48,116
Automotive service
Reconciliation of assets from segment to consolidated
Net real estate	152,220	129,328
Intangible assets	33,160	19,131
Goodwill	440	448
Automotive tire services
Reconciliation of assets from segment to consolidated
Net real estate	238,151	247,200
Intangible assets	11,533	13,202
Goodwill	862	865
Beverages
Reconciliation of assets from segment to consolidated
Net real estate	293,447	297,724
Intangible assets	2,280	2,538
Child care
Reconciliation of assets from segment to consolidated
Net real estate	49,584	52,392
Goodwill	4,945	5,034
Convenience stores
Reconciliation of assets from segment to consolidated
Net real estate	1,050,285	724,972
Intangible assets	14,372	16,040
Goodwill	2,008	2,009
Dollar stores
Reconciliation of assets from segment to consolidated
Net real estate	1,120,896	1,158,948
Intangible assets	51,249	56,420
Drug stores
Reconciliation of assets from segment to consolidated
Net real estate	1,541,846	1,384,506
Intangible assets	182,981	189,433
Financial services
Reconciliation of assets from segment to consolidated
Net real estate	408,228	254,022
Intangible assets	29,749	34,626
General merchandise
Reconciliation of assets from segment to consolidated
Net real estate	248,040	195,030
Intangible assets	43,248	41,301
Grocery stores
Reconciliation of assets from segment to consolidated
Net real estate	464,359	331,565
Intangible assets	65,412	42,823
Health and fitness
Reconciliation of assets from segment to consolidated
Net real estate	823,697	839,872
Intangible assets	63,574	65,037
Health care
Reconciliation of assets from segment to consolidated
Net real estate	214,971	220,018
Intangible assets	25,039	29,950
Home improvement
Reconciliation of assets from segment to consolidated
Net real estate	311,459	268,974
Intangible assets	49,932	42,630
Motor vehicle dealerships
Reconciliation of assets from segment to consolidated
Net real estate	197,713	137,315
Intangible assets	25,032	13,182
Restaurants - casual dining
Reconciliation of assets from segment to consolidated
Net real estate	511,863	419,455
Intangible assets	22,058	9,392
Goodwill	2,107	2,215
Restaurants - quick service
Reconciliation of assets from segment to consolidated
Net real estate	574,532	467,643
Intangible assets	43,356	32,612
Goodwill	1,068	1,082
Theaters
Reconciliation of assets from segment to consolidated
Net real estate	370,732	371,617
Intangible assets	13,822	17,673
Transportation services
Reconciliation of assets from segment to consolidated
Net real estate	796,717	686,041
Intangible assets	101,664	92,602
Wholesale clubs
Reconciliation of assets from segment to consolidated
Net real estate	439,557	452,563
Intangible assets	32,723	36,215
Other
Reconciliation of assets from segment to consolidated
Net real estate	1,920,076	1,799,524
Intangible assets	227,350	231,494
Goodwill	$ 3,637	$ 3,668
Number of non-reportable segments | segment	27	27	27