Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 218,607	$ 190,998
Equity-based compensation expense (2)	(19,333)	(9,509)
Corporate interest expense	(6,215)	(6,282)
Home Building [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	188,410	168,570
Corporate interest expense	(5,993)	(6,007)
Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	30,197	22,428
Corporate interest expense	(222)	(275)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	210,893	179,749
Operating Segments [Member] | Home Building [Member] | Mid Atlantic [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	99,364	91,047
Operating Segments [Member] | Home Building [Member] | North East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	11,460	15,704
Operating Segments [Member] | Home Building [Member] | Mid East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	35,475	27,211
Operating Segments [Member] | Home Building [Member] | South East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	35,036	23,237
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	29,558	22,550
Corporate and Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	7,714	11,249
Contract land deposit reserve adjustment	950	2,128
Equity-based compensation expense (2)	(19,333)	(9,509)
Corporate capital allocation	54,559	50,700
Unallocated corporate overhead	(31,735)	(31,284)
Consolidation adjustments and other	9,247	5,201
Corporate interest expense	(5,974)	(5,987)
Corporate and Reconciling Items [Member] | Home Building [Member] | Mid Atlantic [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	30,417	30,449
Corporate and Reconciling Items [Member] | Home Building [Member] | North East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	4,727	4,180
Corporate and Reconciling Items [Member] | Home Building [Member] | Mid East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	9,015	7,973
Corporate and Reconciling Items [Member] | Home Building [Member] | South East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	$ 10,400	$ 8,098