XML 31 R76.htm IDEA: XBRL DOCUMENT
v3.20.1

Stockholder's Equity - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Class Of Stock [Line Items] |  |  |
Payments of dividends | $ 0 | $ 0 | $ 0
NL |  |  |
Class Of Stock [Line Items] |  |  |
Common stock awarded to board of directors | 28,250 | 12,600 | 9,000
Shares available for award | 113,150 |  |
NL | Maximum |  |  |
Class Of Stock [Line Items] |  |  |
Aggregate of common stock awarded to directors | 200,000 |  |
CompX |  |  |
Class Of Stock [Line Items] |  |  |
Shares available for award | 149,050 |  |
CompX | Maximum |  |  |
Class Of Stock [Line Items] |  |  |
Aggregate of common stock awarded to directors | 200,000 |  |
Kronos |  |  |
Class Of Stock [Line Items] |  |  |
Shares available for award | 140,900 |  |
Kronos | Maximum |  |  |
Class Of Stock [Line Items] |  |  |
Aggregate of common stock awarded to directors | 200,000 |  |

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ClassOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfDividends
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of additional shares authorized for issuance under share-based payment arrangement. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares issued under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=nl_NLMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=nl_CompXInternationalIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=nl_KronosWorldwideIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |