Segment Disclosures - Income before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	$ 241,586	$ 208,968	$ 432,584	$ 341,129
Equity-based compensation expense (2)			(28,104)	(21,467)
Corporate interest expense	(6,329)	(5,914)	(12,611)	(11,750)
Homebuilding [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	223,266	191,337	391,836	308,527
Corporate interest expense	(6,047)	(5,641)	(12,054)	(11,219)
Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	18,320	17,631	40,748	32,602
Corporate interest expense	(282)	(273)	(557)	(531)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	220,060	191,634	399,809	317,910
Operating Segments [Member] \| Homebuilding [Member] \| Mid Atlantic [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	112,221	100,621	203,268	165,109
Operating Segments [Member] \| Homebuilding [Member] \| North East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	16,777	14,112	32,481	23,218
Operating Segments [Member] \| Homebuilding [Member] \| Mid East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	42,174	35,986	69,385	58,145
Operating Segments [Member] \| Homebuilding [Member] \| South East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	29,203	22,911	52,440	37,481
Operating Segments [Member] \| Mortgage Banking [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	19,685	18,004	42,235	33,957
Corporate and Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income before taxes	21,526	17,334	32,775	23,219
Contract land deposit reserve adjustment	592	(2,064)	2,720	(2,792)
Equity-based compensation expense (2)	(18,595)	(10,878)	(28,104)	(21,467)
Corporate capital allocation	53,954	49,646	104,653	95,833
Unallocated corporate overhead	(22,503)	(23,360)	(53,787)	(50,594)
Consolidation adjustments and other	14,109	9,614	19,311	13,427
Corporate interest expense	(6,031)	(5,624)	(12,018)	(11,188)
Corporate and Reconciling Items [Member] \| Homebuilding [Member] \| Mid Atlantic [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	31,501	31,005	61,949	60,130
Corporate and Reconciling Items [Member] \| Homebuilding [Member] \| North East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	4,580	4,133	8,760	7,947
Corporate and Reconciling Items [Member] \| Homebuilding [Member] \| Mid East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	9,057	7,535	17,030	14,277
Corporate and Reconciling Items [Member] \| Homebuilding [Member] \| South East [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Corporate capital allocation	$ 8,816	$ 6,973	$ 16,914	$ 13,479

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Contract land deposit reserve adjustment.

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The corporate capital allocation charge is eliminated in consolidation and is based on the segment’s average net assets employed.

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Unallocated corporate overhead.

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- Definition

The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
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Amount of the cost of borrowed funds accounted for as interest expense.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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-Name Accounting Standards Codification
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