Segment Information, Nature of Operations, and Certain Concentrations - Profit before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	$ 959,732	$ 846,911	$ 661,697
Equity-based compensation expense	(75,701)	(44,562)	(43,598)
Corporate interest expense	(25,081)	(24,185)	(21,707)
Homebuilding:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	871,106	776,370	601,102
Corporate interest expense	(24,036)	(23,037)	(20,621)
Mortgage Banking:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	88,626	70,541	60,595
Corporate interest expense	(1,045)	(1,148)	(1,086)
Profit before taxes:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	918,859	778,136	579,095
Corporate interest expense	(215,016)	(199,586)	(191,146)
Profit before taxes: | Homebuilding: | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	462,178	398,494	301,173
Corporate interest expense	(123,908)	(123,075)	(119,808)
Profit before taxes: | Homebuilding: | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	69,789	60,218	21,947
Corporate interest expense	(17,897)	(16,117)	(18,141)
Profit before taxes: | Homebuilding: | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	175,134	149,639	121,166
Corporate interest expense	(35,804)	(29,663)	(28,307)
Profit before taxes: | Homebuilding: | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	118,296	95,826	71,098
Corporate interest expense	(36,362)	(29,583)	(23,804)
Profit before taxes: | Mortgage Banking:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	93,462	73,959	63,711
Corporate interest expense	(1,045)	(1,148)	(1,086)
Reconciling items:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	40,873	68,775	82,602
Contract land deposit reserve adjustment	783	1,307	10,933
Equity-based compensation expense	(75,701)	(44,562)	(43,598)
Corporate capital allocation charge	213,903	198,384	189,992
Unallocated corporate overhead	(89,973)	(89,514)	(89,376)
Consolidation adjustments and other	15,829	26,143	35,204
Corporate interest expense	$ (23,968)	$ (22,983)	$ (20,553)