Joint Ventures - Additional Information (Detail) $ in Thousands	Dec. 31, 2017 USD ($) lot joint_venture	Dec. 31, 2016 USD ($) lot joint_venture
Joint Ventures [Line Items]
Aggregate investment | $	$ 45,500	$ 49,400
Number of joint ventures | joint_venture	6	6
Expected production of finished lots | lot	7,300	7,400
Total lots controlled by company under the joint venture | lot	3,900	4,200
Total lots either under contract with unrelated parties or not under the current contract | lot	3,400	3,200
Additional funding commitments in the aggregate | $	$ 5,300	$ 6,200
Number of joint ventures with additional funding commitment | joint_venture	3	3
Number of joint ventures NVR is not primary beneficiary | joint_venture	5
Other Assets
Joint Ventures [Line Items]
Aggregate investment | $	$ 45,200	$ 49,000