Segment Disclosures - Corporate Capital Allocation Charge (Detail) - Corporate and Reconciling Items [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 53,954	$ 49,646	$ 104,653	$ 95,833
Homebuilding [Member] | Mid Atlantic [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	31,501	31,005	61,949	60,130
Homebuilding [Member] | North East [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	4,580	4,133	8,760	7,947
Homebuilding [Member] | Mid East [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	9,057	7,535	17,030	14,277
Homebuilding [Member] | South East [Member]
Segment Reporting, Other Significant Reconciling Item [Line Items]
Corporate capital allocation charge	$ 8,816	$ 6,973	$ 16,914	$ 13,479