Segment Disclosures - Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 3,089,823	$ 2,989,279
Contract land deposit reserve	(27,968)	(29,999)
Home Building [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,716,614	2,584,880
Cash and cash equivalents	598,789	645,087
Mortgage Banking [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	373,209	404,399
Cash and cash equivalents	11,081	21,707
Operating Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,289,437	2,160,009
Operating Segments [Member] | Home Building [Member] | Mid Atlantic [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,098,095	1,079,225
Operating Segments [Member] | Home Building [Member] | North East [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	160,541	143,008
Operating Segments [Member] | Home Building [Member] | Mid East [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	324,253	263,019
Operating Segments [Member] | Home Building [Member] | South East [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	340,686	277,705
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	365,862	397,052
Corporate and Reconciling Items [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	800,386	829,270
Cash and cash equivalents	598,789	645,087
Deferred taxes	115,824	111,953
Intangible assets and goodwill	50,028	50,144
Contract land deposit reserve	(27,968)	(29,999)
Consolidation adjustments and other	$ 63,713	$ 52,085