Summary of Significant Accounting Policies - Non-cash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Significant Noncash Transactions [Line Items]
Contribution of net assets to Curbline Properties	$ 1,152,700	$ 0	$ 0
Consolidation of the net assets (excluding mortgages as disclosed below) of previously unconsolidated joint ventures	0	0	42,800
Net assets acquired from unconsolidated joint ventures	0	0	8,500
Dividends declared, but not paid	0	63,806	30,400
Accounts payable related to construction in progress	700	7,000	12,200
Accrued liabilities for sold properties	0	5,400	0
Repurchase of operating partnership units	0	4,100	0
Building [Member]
Other Significant Noncash Transactions [Line Items]
Assumption of buildings due to ground lease terminations	$ 2,700	$ 0	$ 2,900