Segment Information - Assets (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of activity segments | segment	48
Reconciliation of assets from segment to consolidated
Net real estate	$ 14,141,894	$ 13,843,517
Intangible assets	1,205,147	1,199,597
Goodwill	14,597	14,630
Other corporate assets	401,270	202,739
Total assets	15,762,908	15,260,483
Automotive service
Reconciliation of assets from segment to consolidated
Net real estate	253,730	210,668
Intangible assets	60,964	61,951
Goodwill	437	437
Automotive tire services
Reconciliation of assets from segment to consolidated
Net real estate	236,547	238,939
Intangible assets	8,289	8,696
Goodwill	862	862
Beverages
Reconciliation of assets from segment to consolidated
Net real estate	282,536	284,910
Intangible assets	1,701	1,765
Child care
Reconciliation of assets from segment to consolidated
Net real estate	179,267	151,640
Intangible assets	16,189	12,277
Goodwill	4,852	4,863
Convenience stores
Reconciliation of assets from segment to consolidated
Net real estate	1,742,539	1,756,732
Intangible assets	108,993	108,714
Goodwill	1,983	1,983
Dollar stores
Reconciliation of assets from segment to consolidated
Net real estate	1,133,683	1,117,250
Intangible assets	50,416	48,842
Drug stores
Reconciliation of assets from segment to consolidated
Net real estate	1,476,192	1,490,261
Intangible assets	162,099	165,558
Financial services
Reconciliation of assets from segment to consolidated
Net real estate	410,060	414,613
Intangible assets	19,561	20,426
General merchandise
Reconciliation of assets from segment to consolidated
Net real estate	315,593	317,424
Intangible assets	43,731	43,122
Grocery stores
Reconciliation of assets from segment to consolidated
Net real estate	834,051	774,526
Intangible assets	152,867	144,551
Health and fitness
Reconciliation of assets from segment to consolidated
Net real estate	1,001,191	882,515
Intangible assets	68,530	71,609
Home improvement
Reconciliation of assets from segment to consolidated
Net real estate	464,595	424,494
Intangible assets	65,078	57,928
Motor vehicle dealerships
Reconciliation of assets from segment to consolidated
Net real estate	212,941	198,204
Intangible assets	28,834	28,154
Restaurants-casual dining
Reconciliation of assets from segment to consolidated
Net real estate	550,063	559,616
Intangible assets	17,729	18,153
Goodwill	1,825	1,841
Restaurants-quick service
Reconciliation of assets from segment to consolidated
Net real estate	965,007	964,980
Intangible assets	55,364	54,448
Goodwill	1,046	1,052
Theaters
Reconciliation of assets from segment to consolidated
Net real estate	583,252	555,990
Intangible assets	31,014	25,811
Transportation services
Reconciliation of assets from segment to consolidated
Net real estate	752,983	758,133
Intangible assets	70,609	73,577
Wholesale club
Reconciliation of assets from segment to consolidated
Net real estate	408,961	412,203
Intangible assets	25,706	26,484
Other non-reportable segments
Reconciliation of assets from segment to consolidated
Net real estate	2,338,703	2,330,419
Intangible assets	217,473	227,531
Goodwill	$ 3,592	$ 3,592