Segment Information, Nature of Operations, and Certain Concentrations - Interest Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	$ 24,185	$ 21,707	$ 23,559
Homebuilding:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	23,037	20,621	22,918
Mortgage Banking:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	1,148	1,086	641
Profit before taxes:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	199,586	191,146	171,860
Profit before taxes: | Homebuilding: | Mid Atlantic
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	123,075	119,808	107,748
Profit before taxes: | Homebuilding: | North East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	16,117	18,141	16,991
Profit before taxes: | Homebuilding: | Mid East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	29,663	28,307	27,263
Profit before taxes: | Homebuilding: | South East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	29,583	23,804	19,217
Profit before taxes: | Mortgage Banking:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	1,148	1,086	641
Reconciling items:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Consolidated interest expense	22,983	20,553	22,869
Corporate capital allocation charge	198,384	189,992	171,170
Reconciling items: | Homebuilding: | Mid Atlantic
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	123,028	119,758	107,705
Reconciling items: | Homebuilding: | North East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	16,115	18,132	16,987
Reconciling items: | Homebuilding: | Mid East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	29,663	28,303	27,263
Reconciling items: | Homebuilding: | South East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 29,578	$ 23,799	$ 19,215