Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 434,127	$ 321,457	$ 1,163,598	$ 692,663
Contract land deposit reserve adjustment	4,100	(4,800)	17,500	32,500
Equity-based compensation expense			(42,859)	(35,565)
Corporate interest expense	(13,243)	(11,687)	(39,910)	(27,698)
Home Building Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	395,108	269,645	1,026,790	614,369
Corporate interest expense	(12,838)	(11,309)	(38,694)	(26,689)
Mortgage Banking
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	39,019	51,812	136,808	78,294
Corporate interest expense	(405)	(378)	(1,216)	(1,009)
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	478,347	269,525	1,162,978	642,020
Operating Segments | Home Building Segment | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	222,504	104,700	526,052	284,440
Operating Segments | Home Building Segment | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	33,885	14,272	70,622	31,081
Operating Segments | Home Building Segment | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	81,021	45,109	189,849	103,575
Operating Segments | Home Building Segment | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	100,688	52,554	236,272	142,463
Operating Segments | Mortgage Banking
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	40,249	52,890	140,183	80,461
Corporate and Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	(44,220)	51,932	620	50,643
Contract land deposit reserve adjustment	4,126	4,867	17,500	(31,208)
Equity-based compensation expense	(15,009)	(13,639)	(42,859)	(35,565)
Corporate capital allocation	64,055	60,662	188,638	177,184
Unallocated corporate overhead	(27,801)	(26,915)	(101,605)	(87,912)
Consolidation adjustments and other (3)	(56,786)	38,244	(22,456)	54,769
Corporate interest expense	(12,805)	(11,287)	(38,598)	(26,625)
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	31,057	31,383	92,788	92,720
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	6,719	5,793	19,214	17,142
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	11,114	10,386	32,804	29,436
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	$ 15,165	$ 13,100	$ 43,832	$ 37,886