Segment Information, Nature of Operations, and Certain Concentrations - Expenditures for Property and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	$ 19,665	$ 20,269	$ 22,369
Profit before taxes:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	16,442	19,709	20,608
Profit before taxes: | Homebuilding: | Mid Atlantic
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	6,657	9,257	8,838
Profit before taxes: | Homebuilding: | North East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	1,074	1,299	3,423
Profit before taxes: | Homebuilding: | Mid East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	4,302	3,117	4,027
Profit before taxes: | Homebuilding: | South East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	2,732	3,313	3,594
Profit before taxes: | Mortgage Banking:
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	1,677	2,723	726
Other unallocated interest income
Segment Reporting, Other Significant Reconciling Item [Line Items]
Expenditures for property and equipment:	$ 3,223	$ 560	$ 1,761