Segment Information, Nature of Operations, and Certain Concentrations - Profit before Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	$ 453,546	$ 418,696	$ 275,077
Corporate Capital Allocation [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	152,140	116,457	91,507
Homebuilding Mid Atlantic [Member] | Corporate Capital Allocation [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	96,328	72,271	59,144
Homebuilding North East [Member] | Corporate Capital Allocation [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	12,107	9,461	8,187
Homebuilding Mid East [Member] | Corporate Capital Allocation [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	26,299	22,580	15,039
Homebuilding South East [Member] | Corporate Capital Allocation [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	17,406	12,145	9,137
Operating Segments [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	420,806	423,306	309,274
Operating Segments [Member] | Homebuilding Mid Atlantic [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	271,965	276,399	189,089
Operating Segments [Member] | Homebuilding North East [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	33,390	14,294	21,529
Operating Segments [Member] | Homebuilding Mid East [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	47,538	55,537	39,847
Operating Segments [Member] | Homebuilding South East [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	37,525	35,001	20,674
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Consolidated profit before taxes	30,388	42,075	38,135
Reconciling Items Sub-Total [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	32,740	(4,610)	(34,197)
Reconciling Items Sub-Total [Member] | Contract Land Deposit Reserve Adjustment [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	3,612	5,313	5,333
Reconciling Items Sub-Total [Member] | Equity-Based Compensation Expense [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	(63,227)	(34,296)	(64,841)
Reconciling Items Sub-Total [Member] | Corporate Capital Allocation [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	152,140	116,457	91,507
Reconciling Items Sub-Total [Member] | Unallocated Corporate Overhead [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	(61,108)	(72,703)	(70,258)
Reconciling Items Sub-Total [Member] | Corporate Interest Expense [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	(22,544)	(21,743)	(6,796)
Consolidation adjustments and other [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment reporting reconciling item for operating profit	$ 23,867	$ 2,362	$ 10,858