Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 190,998	$ 132,161
Equity-based compensation expense	(9,509)	(10,589)
Corporate interest expense	(6,282)	(5,836)
Homebuilding [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	168,570	117,190
Corporate interest expense	(6,007)	(5,578)
Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	22,428	14,971
Corporate interest expense	(275)	(258)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	179,749	126,276
Operating Segments [Member] | Homebuilding [Member] | Mid Atlantic [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	91,047	64,489
Operating Segments [Member] | Homebuilding [Member] | North East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	15,704	9,106
Operating Segments [Member] | Homebuilding [Member] | Mid East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	27,211	22,159
Operating Segments [Member] | Homebuilding [Member] | South East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	23,237	14,569
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	22,550	15,953
Corporate and Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	11,249	5,885
Contract land deposit reserve adjustment	2,128	(728)
Equity-based compensation expense	(9,509)	(10,589)
Corporate capital allocation	50,700	46,187
Unallocated corporate overhead	(31,284)	(27,234)
Consolidation adjustments and other	5,201	3,813
Corporate interest expense	(5,987)	(5,564)
Corporate and Reconciling Items [Member] | Homebuilding [Member] | Mid Atlantic [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	30,449	29,124
Corporate and Reconciling Items [Member] | Homebuilding [Member] | North East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	4,180	3,814
Corporate and Reconciling Items [Member] | Homebuilding [Member] | Mid East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	7,973	6,742
Corporate and Reconciling Items [Member] | Homebuilding [Member] | South East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	$ 8,098	$ 6,507