Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 249,710	$ 244,464	$ 682,294	$ 585,593
Equity-based compensation expense (2)			(51,690)	(32,678)
Corporate interest expense	(6,197)	(6,120)	(18,808)	(17,870)
Home Building [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	224,196	226,043	616,032	534,570
Corporate interest expense	(5,968)	(5,821)	(18,022)	(17,040)
Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	25,514	18,421	66,262	51,023
Corporate interest expense	(229)	(299)	(786)	(830)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	244,093	219,354	643,902	537,265
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	115,180	109,417	318,447	274,527
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	18,560	18,762	51,041	41,980
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	51,744	44,990	121,129	103,135
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	31,426	26,849	83,867	64,330
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	27,183	19,336	69,418	53,293
Corporate and Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	5,617	25,110	38,392	48,328
Contract land deposit reserve adjustment	(689)	1,910	2,031	(882)
Equity-based compensation expense (2)	(23,586)	(11,211)	(51,690)	(32,678)
Corporate capital allocation	55,438	51,904	160,091	147,737
Unallocated corporate overhead	(20,424)	(18,768)	(74,211)	(69,362)
Consolidation adjustments and other	831	7,087	20,142	20,513
Corporate interest expense	(5,953)	(5,812)	(17,971)	(17,000)
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	31,733	32,025	93,682	92,154
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	4,565	4,244	13,325	12,191
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	9,541	7,747	26,571	22,024
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	$ 9,599	$ 7,888	$ 26,513	$ 21,368