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Mortgage Loan Losses Allowance - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Mortgage Repurchase Reserve [Abstract] |  |  |
Pre-tax charges for loan losses related to mortgage loans sold | $ 2,900 | $ 2,000 | $ 2,700
Mortgage repurchase reserve | $ 14,000 | $ 12,700 |

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- Definition Mortgage Repurchase Reserve [Abstract] + References No definition available. + Details
Name: | nvr_MortgageRepurchaseReserveAbstract
Namespace Prefix: | nvr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Mortgage Repurchase Reserve, Real Estate + References No definition available. + Details
Name: | nvr_MortgageRepurchaseReserveRealEstate
Namespace Prefix: | nvr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Amount of expense related to loss from loan transactions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
Name: | us-gaap_ProvisionForLoanLossesExpensed
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration