Recent Transactions (Details) $ in Thousands			1 Months Ended		3 Months Ended			9 Months Ended
	Jul. 16, 2020 USD ($) hotel_room	Mar. 13, 2020 USD ($) ft² a parking_spaces	Nov. 30, 2019 USD ($)	Oct. 31, 2019 a	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jul. 15, 2020	Dec. 31, 2019 USD ($)
Real Estate [Line Items]
Gain (loss) on sale or disposal of real estate and other assets, net					$ 108		$ 24,201	$ 46,232	$ 24,051
Proceeds from sales of properties								0	9,460
Net investment in lease receivable					2,928			2,928			$ 79,166
Selling profit from sales-type leases					$ 0		$ 13,537	0	13,537
Proceeds from the sale of lease receivable								64,155	$ 0
West Windsor
Real Estate [Line Items]
Area of land sold (in acres) | a				659
Gain (loss) on sale or disposal of real estate and other assets, net								8,000
100 Fellowship Drive
Real Estate [Line Items]
Area of land sold (in acres) | a		13.5
Gain (loss) on sale or disposal of real estate and other assets, net						$ 38,300
Square footage of buildings sold (in sqft) | ft²		203,257
Number of parking spaces | parking_spaces		550
Proceeds from sales of properties		$ 115,000
Sales-type lease, derecognized developments			$ 63,700
Net investment in lease receivable		76,100	75,900
Selling profit from sales-type leases			$ 13,500
Transaction costs on sales of investments real estate		200
Payments to acquire real estate		$ 600
Proceeds from the sale of lease receivable								$ 64,200
Mr. C Seaport
Real Estate [Line Items]
Number of hotel rooms | hotel_room	66
Equity method investment, proceeds from sale	$ 800
Equity Method Investments | Mr. C Seaport
Real Estate [Line Items]
Equity method investment, ownership percentage										35.00%
Number of hotel rooms | hotel_room	66