Real Estate Portfolio (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) ft² site state	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) ft² state
Real Estate Portfolio
Number of Real Estate Properties	868		821
Number of states | state	46		46
Land Subject to Ground Leases | ft²	16,300,000		14,600,000
Net Real Estate Investments	$ 2,397,615,000		$ 2,218,592,000
Payments to Acquire Property, Plant, and Equipment	$ 227,000,000.0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (in year)	11 years
Deferred Revenue	$ 2,100,000		$ 4,100,000
Retail Net Lease Assets Purchased	51
Number of Development and Partner Capital Solutions Projects Construction	1
Number Of States Properties Located	24
Number of Contracts or Customers Comprising Ten Percent or More Of Company's Total Assets or Total Rent		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Land	$ 63,000,000.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Buildings	144,700,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	$ 19,300,000
Number of properties sold	6
Proceeds from Sale of Real Estate	$ 24,400,000
Gains (Losses) on Sales of Investment Real Estate	1,600,000
Provision for impairment	$ 0	$ 416,000
Impaired Real Estate Estate Fair Value		$ 600,000