Acquisitions (Details) $ in Thousands				1 Months Ended	9 Months Ended
	Sep. 17, 2021 USD ($) ft² property	Jun. 23, 2021 USD ($)	Jun. 22, 2021 USD ($)	Jul. 31, 2021 USD ($)	Sep. 30, 2021 USD ($) numberofaquisitiontransactions	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Payments to acquire land subject to ground lease					$ 586,927	$ 0
Number of development property transactions | numberofaquisitiontransactions					2
Ground lease right-of-use asset					$ 127,657		$ 95,523
Ground lease liabilities					125,676		$ 97,778
Development Properties [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Purchase price					$ 622,200
2001 West 8th Avenue, Seattle, WA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of operating properties acquired | property	1
Rentable Square Feet | ft²	539,226
Purchase price	$ 490,000
601 108th Avenue NE, Bellevue, WA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Payments to acquire land subject to ground lease				$ 47,000
2045 Pacific Highway, San Diego, CA [Member] | Development Properties [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Purchase price			$ 42,000
Accrued environmental remediation liabilities			$ 5,200
200 W. 6th Street, Austin, TX [Member] | Development Properties [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Purchase price		$ 580,200
Ground lease right-of-use asset		46,400
Ground lease liabilities		$ 46,400
Discount rate (percent)		3.97%