Related Party Transactions - Additional Information (Detail) - Elm Street	12 Months Ended
	Dec. 31, 2018 USD ($) lot	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Related Party Transaction [Line Items]
Related party forward lot purchase agreements purchase price	$ 121,700,000
Number of related parties for forward lot purchase agreement | lot	1
Market price of developed lots	$ 36,100,000	$ 37,100,000	$ 44,500,000
Expected number of lots from joint venture with Elm Street | lot	2,300
Additional funding to joint venture by NVR and Elm Street		2,900,000
Development costs to manage property under related party transactions	$ 0	$ 0	$ 143,000