Investments in and Advances to Joint Ventures - Revenues Earned By the Company from Unconsolidated Joint Ventures and Interest Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from contracts:
Total revenue from contracts with customers	$ 9,100	$ 11,945	$ 32,466	$ 42,928
Other:
Interest income	3,500	4,200	10,500	12,600
Other	500	800	1,700	2,300
Other, Total	4,000	5,000	12,200	14,900
Revenue and other income	7,600	10,900	25,900	33,400
Asset and Property Management Fees [Member]
Revenue from contracts:
Total revenue from contracts with customers	7,326	9,751	24,201	32,392
Unconsolidated Joint Ventures [Member]
Revenue from contracts:
Total revenue from contracts with customers	3,600	5,900	13,700	18,500
Unconsolidated Joint Ventures [Member] | Asset and Property Management Fees [Member]
Revenue from contracts:
Total revenue from contracts with customers	3,000	4,700	10,100	14,800
Unconsolidated Joint Ventures [Member] | Development Fees, Leasing Commissions and Other [Member]
Revenue from contracts:
Total revenue from contracts with customers	$ 600	$ 1,200	$ 3,600	$ 3,700