Segment Disclosures - Corporate Capital Allocation Charge (Detail) - Corporate and Reconciling Items [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 50,700	$ 46,187
Homebuilding [Member] | Mid Atlantic [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	30,449	29,124
Homebuilding [Member] | North East [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	4,180	3,814
Homebuilding [Member] | Mid East [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	7,973	6,742
Homebuilding [Member] | South East [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 8,098	$ 6,507