Segment Information - Assets (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($) segment	Dec. 31, 2020 USD ($)
Segment Reporting [Abstract]
Number of activity segments | segment	58
Reconciliation of assets from segment to consolidated
Net real estate	$ 18,939,703	$ 17,485,156
Intangible assets	1,969,793	1,710,655
Other corporate assets	1,075,303	1,544,474
Total assets	21,984,941	20,740,285
Automotive service
Reconciliation of assets from segment to consolidated
Net real estate	382,764	328,340
Intangible assets	56,319	55,018
Beverages
Reconciliation of assets from segment to consolidated
Net real estate	362,944	347,366
Intangible assets	17,146	9,401
Child care
Reconciliation of assets from segment to consolidated
Net real estate	215,132	216,718
Intangible assets	18,852	19,848
Convenience stores
Reconciliation of assets from segment to consolidated
Net real estate	2,198,309	2,101,005
Intangible assets	116,621	121,151
Dollar stores
Reconciliation of assets from segment to consolidated
Net real estate	1,449,235	1,420,210
Intangible assets	87,620	77,176
Drug stores
Reconciliation of assets from segment to consolidated
Net real estate	1,520,877	1,555,106
Intangible assets	160,033	167,975
Financial services
Reconciliation of assets from segment to consolidated
Net real estate	367,545	374,508
Intangible assets	13,267	14,611
General merchandise
Reconciliation of assets from segment to consolidated
Net real estate	883,230	730,806
Intangible assets	138,486	108,646
Grocery stores - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	907,465	907,634
Intangible assets	180,333	181,764
Grocery stores - U.K.
Reconciliation of assets from segment to consolidated
Net real estate	1,492,945	1,131,760
Intangible assets	363,254	282,211
Health and fitness
Reconciliation of assets from segment to consolidated
Net real estate	1,023,606	1,050,791
Intangible assets	63,290	67,537
Home improvement - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	666,622	608,222
Intangible assets	100,259	97,228
Home improvement - U.K.
Reconciliation of assets from segment to consolidated
Net real estate	464,102	187,289
Intangible assets	118,272	57,369
Restaurants-casual dining
Reconciliation of assets from segment to consolidated
Net real estate	493,962	515,226
Intangible assets	18,654	20,553
Restaurants-quick service - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	1,123,317	1,062,918
Intangible assets	44,951	47,517
Theaters - U.S.
Reconciliation of assets from segment to consolidated
Net real estate	752,439	767,117
Intangible assets	26,650	28,292
Transportation services
Reconciliation of assets from segment to consolidated
Net real estate	778,149	729,640
Intangible assets	56,913	53,902
Wholesale club
Reconciliation of assets from segment to consolidated
Net real estate	441,279	407,584
Intangible assets	52,227	36,165
Other non-reportable segments
Reconciliation of assets from segment to consolidated
Net real estate	3,415,781	3,042,916
Intangible assets	$ 336,788	$ 264,291