Segment Information, Nature of Operations, and Certain Concentrations - Profit before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	$ 846,911	$ 661,697	$ 603,212
Equity-based compensation expense	(44,562)	(43,598)	(54,091)
Corporate interest expense	(24,185)	(21,707)	(23,559)
Homebuilding:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	776,370	601,102	555,329
Corporate interest expense	(23,037)	(20,621)	(22,918)
Mortgage Banking:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	70,541	60,595	47,883
Corporate interest expense	(1,148)	(1,086)	(641)
Profit before taxes:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	778,136	579,095	555,699
Corporate interest expense	(199,586)	(191,146)	(171,860)
Profit before taxes: | Homebuilding: | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	398,494	301,173	322,829
Corporate interest expense	(123,075)	(119,808)	(107,748)
Profit before taxes: | Homebuilding: | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	60,218	21,947	37,914
Corporate interest expense	(16,117)	(18,141)	(16,991)
Profit before taxes: | Homebuilding: | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	149,639	121,166	86,336
Corporate interest expense	(29,663)	(28,307)	(27,263)
Profit before taxes: | Homebuilding: | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	95,826	71,098	57,384
Corporate interest expense	(29,583)	(23,804)	(19,217)
Profit before taxes: | Mortgage Banking:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	73,959	63,711	51,236
Corporate interest expense	(1,148)	(1,086)	(641)
Reconciling items:
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Profit before taxes	68,775	82,602	47,513
Contract land deposit reserve adjustment	1,307	10,933	13,805
Equity-based compensation expense	(44,562)	(43,598)	(54,091)
Corporate capital allocation charge	198,384	189,992	171,170
Unallocated corporate overhead	(89,514)	(89,376)	(83,124)
Consolidation adjustments and other	26,143	35,204	22,622
Corporate interest expense	(22,983)	(20,553)	(22,869)
Reconciling items: | Homebuilding: | Mid Atlantic
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation charge	123,028	119,758	107,705
Reconciling items: | Homebuilding: | North East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation charge	16,115	18,132	16,987
Reconciling items: | Homebuilding: | Mid East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation charge	29,663	28,303	27,263
Reconciling items: | Homebuilding: | South East
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation charge	$ 29,578	$ 23,799	$ 19,215