Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 417,465	$ 209,831	$ 729,471	$ 371,206
Contract land deposit reserve adjustment	7,200		13,400
Equity-based compensation expense			(27,850)	(21,926)
Corporate interest expense	(13,270)	(9,525)	(26,667)	(16,011)
Home Building Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	378,263	194,805	631,682	344,724
Corporate interest expense	(12,850)	(9,166)	(25,856)	(15,380)
Mortgage Banking
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	39,202	15,026	97,789	26,482
Corporate interest expense	(420)	(359)	(811)	(631)
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	375,169	190,484	684,631	372,495
Operating Segments | Home Building Segment | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	174,481	98,067	303,548	179,740
Operating Segments | Home Building Segment | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	21,510	6,658	36,737	16,809
Operating Segments | Home Building Segment | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	59,887	27,302	108,828	58,466
Operating Segments | Home Building Segment | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	78,919	42,765	135,584	89,909
Operating Segments | Mortgage Banking
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	40,372	15,692	99,934	27,571
Corporate and Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	42,296	19,347	44,840	(1,289)
Contract land deposit reserve adjustment	7,178	(460)	13,374	(36,075)
Equity-based compensation expense	(13,379)	(14,434)	(27,850)	(21,926)
Corporate capital allocation	63,032	59,870	124,583	116,521
Unallocated corporate overhead	(33,668)	(23,288)	(73,804)	(60,927)
Consolidation adjustments and other (3)	31,944	6,803	34,330	16,456
Corporate interest expense	(12,811)	(9,144)	(25,793)	(15,338)
Corporate and Reconciling Items | Home Building Segment | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	31,135	31,581	61,731	61,336
Corporate and Reconciling Items | Home Building Segment | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	6,457	5,790	12,495	11,349
Corporate and Reconciling Items | Home Building Segment | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	11,066	9,687	21,690	19,050
Corporate and Reconciling Items | Home Building Segment | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	$ 14,374	$ 12,812	$ 28,667	$ 24,786