Segment Information, Nature of Operations, and Certain Concentrations - Corporate Capital Allocation Charge (Detail) - Reconciling items: - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 198,384	$ 189,992	$ 171,170
Homebuilding: | Mid Atlantic
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	123,028	119,758	107,705
Homebuilding: | North East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	16,115	18,132	16,987
Homebuilding: | Mid East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	29,663	28,303	27,263
Homebuilding: | South East
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 29,578	$ 23,799	$ 19,215