Investments in and Advances to Joint Ventures - Revenues Earned By the Company from Unconsolidated Joint Ventures and Interest Income (Detail) - Unconsolidated Joint Ventures [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenue from contracts:
Total revenue from contracts with customers	$ 2.8	$ 3.1	$ 5.5	$ 6.1
Other	0.2	0.4	0.6	0.8
Revenue and other income	3.0	3.5	6.1	6.9
Asset and Property Management Fees [Member]
Revenue from contracts:
Total revenue from contracts with customers	2.2	2.6	4.5	5.2
Leasing commissions and development fees [Member]
Revenue from contracts:
Total revenue from contracts with customers	$ 0.6	$ 0.5	$ 1.0	$ 0.9