Impairment Charges and Reserves - Impairment Charges on Assets or Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Impairment Charges And Impairment Of Joint Venture Investments [Abstract]
Reserve of preferred equity interests	$ 19,393	$ 15,544	$ 11,422
Assets marketed for sale	3,200	600	5,800
Assets included in the spin-off of RVI	0	0	62,600
Total impairment charges	24,600	18,900	80,700
Undeveloped Land [Member]
Impairment Charges And Impairment Of Joint Venture Investments [Abstract]
Assets marketed for sale	$ 2,000	$ 2,800	$ 900

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228

Name:	us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration