Segment Information, Nature of Operations, and Certain Concentrations - Expenditures for Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	$ 31,672	$ 19,016	$ 12,365
Operating Segments [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	24,392	18,278	9,613
Operating Segments [Member] | Homebuilding Mid Atlantic [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	9,047	7,947	3,595
Operating Segments [Member] | Homebuilding North East [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	2,311	1,454	1,703
Operating Segments [Member] | Homebuilding Mid East [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	6,982	3,282	1,886
Operating Segments [Member] | Homebuilding South East [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	3,472	2,662	1,260
Operating Segments [Member] | Mortgage Banking [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	2,580	2,933	1,169
Consolidation adjustments and other [Member] | Unallocated Corporate Overhead [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Consolidated expenditures for property and equipment	$ 7,280	$ 738	$ 2,752