Segment Information, Nature of Operations, and Certain Concentrations - Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues									$ 7,163,674	$ 6,305,840	$ 5,822,544
Homebuilding:
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues	$ 1,954,403	$ 1,809,345	$ 1,750,463	$ 1,490,093	$ 1,781,494	$ 1,633,726	$ 1,512,714	$ 1,247,587	7,004,304	6,175,521	5,709,223
Homebuilding: | Mid Atlantic
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues									3,893,358	3,543,687	3,319,776
Homebuilding: | North East
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues									580,726	517,141	462,385
Homebuilding: | Mid East
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues									1,455,834	1,250,165	1,192,472
Homebuilding: | South East
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues									1,074,386	864,528	734,590
Mortgage Banking:
Segment Reporting, Revenue Reconciling Item [Line Items]
Consolidated revenues	$ 40,145	$ 43,062	$ 36,842	$ 39,321	$ 34,842	$ 34,194	$ 31,778	$ 29,505	$ 159,370	$ 130,319	$ 113,321