Joint Ventures - Additional Information (Detail) $ in Thousands	3 Months Ended
	Sep. 30, 2018 USD ($) joint_venture lot	Dec. 31, 2017 USD ($)
Joint Ventures [Line Items]
Aggregate investment	$ 31,750
Number of joint ventures | joint_venture	6
Expected production of finished lots | lot	6,900
Total lots controlled by company under the joint venture | lot	3,550
Total lots either under contract with unrelated parties or not under the current contract | lot	3,350
Additional funding commitments in the aggregate	$ 5,000
Number of joint ventures with additional funding commitment | joint_venture	3
Number of joint ventures NVR is not primary beneficiary | joint_venture	5
Other Assets [Member]
Joint Ventures [Line Items]
Aggregate investment	$ 31,750	$ 49,000
Cost of Sales [Member]
Joint Ventures [Line Items]
Equity Method Investment, Other than Temporary Impairment	7,400
EquityMethodInvestmentOtherThanTemporaryImpairmentCapitalizedInterestPortion	$ 760