Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 321,457		$ 267,174	$ 692,663	$ 730,493
Contract land deposit reserve adjustment	(4,800)	$ 36,400		32,500
Equity-based compensation expense (2)				(35,565)	(58,680)
Corporate interest expense	(11,687)		(6,293)	(27,698)	(18,809)
Home Building [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	269,645		245,774	614,369	653,834
Corporate interest expense	(11,309)		(6,008)	(26,689)	(18,034)
Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	51,812		21,400	78,294	76,659
Corporate interest expense	(378)		(285)	(1,009)	(775)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	269,525		250,830	642,020	694,378
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	104,700		124,900	284,440	348,067
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	14,272		13,164	31,081	36,187
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	45,109		50,210	103,575	125,976
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	52,554		39,721	142,463	105,582
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	52,890		22,835	80,461	78,566
Corporate and Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	51,932		16,344	50,643	36,115
Contract land deposit reserve adjustment	4,867		248	(31,208)	1,572
Equity-based compensation expense (2)	(13,639)		(20,770)	(35,565)	(58,680)
Corporate capital allocation	60,662		57,887	177,184	168,621
Unallocated corporate overhead	(26,915)		(27,914)	(87,912)	(89,003)
Consolidation adjustments and other (4)	38,244		12,859	54,769	31,569
Corporate interest expense	(11,287)		(5,966)	(26,625)	(17,964)
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	31,383		31,504	92,720	93,297
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	5,793		5,028	17,142	14,381
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	10,386		9,791	29,436	28,303
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	$ 13,100		$ 11,564	$ 37,886	$ 32,640