CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - Cash and Restricted Cash (Parenthetical)	Mar. 31, 2021 USD ($) property		Feb. 28, 2021	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)		Dec. 31, 2019 USD ($)
Cash and cash equivalents	$ 843,237,000			$ 74,417,000	$ 69,545,000
Restricted cash	326,768,000	[1]		16,432,000	15,691,000	[1]
Total cash and cash equivalents and restricted cash shown in our condensed consolidated statements of cash flows	$ 1,170,005,000			$ 90,849,000	$ 85,236,000		$ 52,224,000
Number of properties (property) | property	396
Senior Unsecured Notes Due June 2021 | Senior Unsecured Notes
Debt face amount	$ 300,000,000
Interest rate (as a percent)			6.75%
Life Science Property | Joint Venture
Ownership percentage	55.00%

[1] As of March 31, 2021, restricted cash includes amounts we will use to redeem all $300,000 of our outstanding 6.75% senior notes due 2021 in June 2021, when these notes become redeemable with no prepayment premium. In April 2021, we delivered a notice of redemption with respect to these senior notes for a redemption price equal to the principal amount plus accrued and unpaid interest. Restricted cash also consists of amounts escrowed for real estate taxes, insurance and capital expenditures at certain of our mortgaged properties and cash held for the operations of the life science property that is owned in a joint venture arrangement in which we own a 55% equity interest.