Segment Information - Assets (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($) property segment	Dec. 31, 2020 USD ($)
Segment Reporting [Abstract]
Number of activity segments | segment	60
Reconciliation of assets from segment to consolidated
Net real estate	$ 19,822,529	$ 17,485,156
Intangible assets	2,156,008	1,710,655
Other corporate assets	1,732,373	1,544,474
Total assets	$ 23,711,094	20,740,285
Number of properties owned | property	7,018
Automotive service
Reconciliation of assets from segment to consolidated
Net real estate	$ 434,668	328,340
Intangible assets	55,313	55,018
Beverages
Reconciliation of assets from segment to consolidated
Net real estate	361,274	347,366
Intangible assets	16,791	9,401
Child care
Reconciliation of assets from segment to consolidated
Net real estate	221,946	216,718
Intangible assets	19,419	19,848
Convenience stores
Reconciliation of assets from segment to consolidated
Net real estate	2,319,783	2,101,005
Intangible assets	152,875	121,151
Dollar stores
Reconciliation of assets from segment to consolidated
Net real estate	1,550,889	1,420,210
Intangible assets	116,556	77,176
Drug stores
Reconciliation of assets from segment to consolidated
Net real estate	1,502,930	1,555,106
Intangible assets	157,073	167,975
Financial services
Reconciliation of assets from segment to consolidated
Net real estate	361,002	374,508
Intangible assets	12,611	14,611
General merchandise
Reconciliation of assets from segment to consolidated
Net real estate	887,969	730,806
Intangible assets	136,367	108,646
Grocery stores - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	899,193	907,634
Intangible assets	177,635	181,764
Grocery stores - U.K.
Reconciliation of assets from segment to consolidated
Net real estate	1,608,133	1,131,760
Intangible assets	374,515	282,211
Health and fitness
Reconciliation of assets from segment to consolidated
Net real estate	1,004,119	1,050,791
Intangible assets	61,172	67,537
Home improvement - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	669,911	608,222
Intangible assets	99,152	97,228
Home improvement - U.K.
Reconciliation of assets from segment to consolidated
Net real estate	593,360	187,289
Intangible assets	132,761	57,369
Restaurants-casual dining
Reconciliation of assets from segment to consolidated
Net real estate	486,625	515,226
Intangible assets	18,194	20,553
Restaurants-quick service - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	1,160,271	1,062,918
Intangible assets	44,037	47,517
Theaters - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	745,180	767,117
Intangible assets	25,925	28,292
Transportation services
Reconciliation of assets from segment to consolidated
Net real estate	782,170	729,640
Intangible assets	56,521	53,902
Wholesale club
Reconciliation of assets from segment to consolidated
Net real estate	455,390	407,584
Intangible assets	61,943	36,165
Other non-reportable segments
Reconciliation of assets from segment to consolidated
Net real estate	3,777,716	3,042,916
Intangible assets	$ 437,332	$ 264,291
Spain
Reconciliation of assets from segment to consolidated
Number of properties owned | property	7