Real Estate Inventories - Additional Information (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($) Project	Dec. 31, 2017 USD ($) Project
Real Estate Properties [Line Items]
Number of projects classified as held for sale \| Project	0	0
Impairment charges	$ 2,232	$ 526
Washington D.C. [Member]
Real Estate Properties [Line Items]
Impairment charges	$ 2,200	$ 500

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-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

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