Investments in and Advances to Joint Ventures - Revenues Earned by Company's Unconsolidated Joint Ventures and Interest Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from contracts:
Total revenue from contracts with customers	$ 41,413	$ 55,988	$ 42,788
Other:
Interest income	12,000	16,700	19,000
Other	2,100	3,200	2,600
Other, Total	14,100	19,900	21,600
Revenue and other income	31,100	44,800	47,300
Asset and Property Management Fees [Member]
Revenue from contracts:
Total revenue from contracts with customers	31,255	42,355	31,751
Unconsolidated Joint Ventures [Member]
Revenue from contracts:
Total revenue from contracts with customers	17,000	24,900	25,700
Unconsolidated Joint Ventures [Member] | Asset and Property Management Fees [Member]
Revenue from contracts:
Total revenue from contracts with customers	12,800	19,700	18,800
Unconsolidated Joint Ventures [Member] | Development Fees, Leasing Commissions and Other [Member]
Revenue from contracts:
Total revenue from contracts with customers	$ 4,200	$ 5,200	$ 6,900