Segment Information, Nature of Operations, and Certain Concentrations - Profit before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	$ 1,078,033	$ 1,025,795	$ 959,732
Equity-based compensation expense (2)	(50,794)	(78,532)	(75,701)
Corporate interest expense	(40,872)	(25,380)	(25,081)
Home Building
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	937,960	923,879	871,106
Corporate interest expense	(39,458)	(24,335)	(24,036)
Mortgage Banking
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	140,073	101,916	88,626
Corporate interest expense	(1,414)	(1,045)	(1,045)
Profit before taxes:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	1,005,479	964,075	918,859
Corporate interest expense	(240,749)	(225,627)	(215,016)
Profit before taxes: | Home Building | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	437,849	478,537	462,178
Corporate interest expense	(124,486)	(123,178)	(123,908)
Profit before taxes: | Home Building | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	50,677	51,728	69,789
Corporate interest expense	(22,859)	(19,804)	(17,897)
Profit before taxes: | Home Building | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	168,605	173,374	175,134
Corporate interest expense	(40,261)	(37,266)	(35,804)
Profit before taxes: | Home Building | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	205,029	155,144	118,296
Corporate interest expense	(51,729)	(44,334)	(36,362)
Profit before taxes: | Mortgage Banking
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	143,319	105,292	93,462
Corporate interest expense	(1,414)	(1,045)	(1,045)
Reconciling items:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	72,554	61,720	40,873
Contract land deposit reserve adjustment	(24,633)	1,644	783
Equity-based compensation expense (2)	(50,794)	(78,532)	(75,701)
Corporate capital allocation charge	239,233	224,468	213,903
Unallocated corporate overhead	(114,921)	(105,125)	(89,973)
Consolidation adjustments and other (3)	63,025	43,486	15,829
Corporate interest expense	$ (39,356)	$ (24,221)	$ (23,968)