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The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. 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Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Service Cost (Component of Net Periodic Pension Cost) -URI http://asc.fasb.org/extlink&oid=6525008 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2Service cost5false 4us-gaap_DefinedBenefitPlanInterestCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse218000218000USD$falsefalsefalse2truefalsefalse232000232000USD$falsefalsefalse3truefalsefalse436000436000USD$falsefalsefalse4truefalsefalse464000464000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Interest cost6false 4us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssetsus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsetruenegatedTerseLabel1truefalsefalse-283000-283000USD$falsefalsefalse2truefalsefalse-267000-267000USD$falsefalsefalse3truefalsefalse-567000-567000USD$falsefalsefalse4truefalsefalse-535000-535000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAn amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. 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This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Amortization of prior service cost8false 4us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLossesus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse203000203000USD$falsefalsefalse2truefalsefalse197000197000USD$falsefalsefalse3truefalsefalse406000406000USD$falsefalsefalse4truefalsefalse393000393000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 158 -Paragraph 7 -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Amortization of net loss9false 4us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse186000186000USD$falsefalsefalse2truefalsefalse206000206000USD$falsefalsefalse3truefalsefalse372000372000USD$falsefalsefalse4truefalsefalse411000411000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 true2Net periodic benefit cost10false 4nwli_DefinedBenefitPlanMinimumRequiredEmployerContributionsForCurrentPlanYearnwli_falsedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse700000700000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse700000700000USD$falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryDefined Benefit Plan, Minimum Required Employer Contributions For Current Plan YearNo definition available.false2Minimum required contribution11false 4us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInCurrentFiscalYearus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse400000400000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse400000400000USD$falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.No definition available.false2Company expected contributions to plans in fiscal year12false 4nwli_DefinedBenefitPlanEmployerContributionsPayableFromPriorPlanYearsnwli_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5truefalsefalse100000100000USD$falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryDefined Benefit Plan, Employer Contributions Payable, From Prior Plan YearsNo definition available.false2Contributions payable, from prior plan years13false 4us-gaap_DefinedBenefitPlanContributionsByEmployerus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse200000200000USD$falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe increase in the fair value of plan assets from contributions made by the employer.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2Company contributions to plan14false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7false USDtruefalse$D2013Q2_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_us-gaap_OtherPensionPlansDefinedBenefitMemberhttp://www.sec.gov/CIK0000070684duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseChairman and President Non-Qualified Defined Benefit Plans [Member]us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherPensionPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Chairman and President Non-Qualified Defined Benefit Plans [Member]15true 3us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]16false 4us-gaap_DefinedBenefitPlanServiceCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse4500045000USD$falsefalsefalse2truefalsefalse4200042000USD$falsefalsefalse3truefalsefalse8900089000USD$falsefalsefalse4truefalsefalse8400084000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Service Cost (Component of Net Periodic Pension Cost) -URI http://asc.fasb.org/extlink&oid=6525008 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2Service cost17false 4us-gaap_DefinedBenefitPlanInterestCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse200000200000USD$falsefalsefalse2truefalsefalse228000228000USD$falsefalsefalse3truefalsefalse400000400000USD$falsefalsefalse4truefalsefalse456000456000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Interest cost18false 4us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCreditus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse1400014000USD$falsefalsefalse2truefalsefalse1500015000USD$falsefalsefalse3truefalsefalse2900029000USD$falsefalsefalse4truefalsefalse3000030000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Amortization of prior service cost19false 4us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLossesus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse293000293000USD$falsefalsefalse2truefalsefalse286000286000USD$falsefalsefalse3truefalsefalse587000587000USD$falsefalsefalse4truefalsefalse571000571000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 158 -Paragraph 7 -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Amortization of net loss20false 4us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse552000552000USD$falsefalsefalse2truefalsefalse571000571000USD$falsefalsefalse3truefalsefalse11050001105000USD$falsefalsefalse4truefalsefalse11410001141000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 true2Net periodic benefit cost21false 4us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInCurrentFiscalYearus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse20000002000000USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse20000002000000USD$falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.No definition available.false2Company expected contributions to plans in fiscal year22false 4us-gaap_DefinedBenefitPlanContributionsByEmployerus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse900000900000USD$falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe increase in the fair value of plan assets from contributions made by the employer.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2Company contributions to plan23false 4us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncreaseus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3truetruefalse0.10.1falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsenum:percentItemTypepureExpected rate of compensation increases (for pay-related plans).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph j -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Aggregate average annual participant salary increase (as a percentage)24false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse11false USDtruefalse$D2013Q2_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMemberhttp://www.sec.gov/CIK0000070684duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseDefined Benefit Postretirement Healthcare Plans [Member]us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Defined Benefit Postretirement Healthcare Plans [Member]25true 3us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]26false 4us-gaap_DefinedBenefitPlanInterestCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3000030000USD$falsefalsefalse2truefalsefalse3300033000USD$falsefalsefalse3truefalsefalse5900059000USD$falsefalsefalse4truefalsefalse6500065000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Interest cost27false 4us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCreditus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse2500025000USD$falsefalsefalse2truefalsefalse2600026000USD$falsefalsefalse3truefalsefalse5100051000USD$falsefalsefalse4truefalsefalse5200052000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Amortization of prior service cost28false 4us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLossesus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse80008000USD$falsefalsefalse2truefalsefalse90009000USD$falsefalsefalse3truefalsefalse1600016000USD$falsefalsefalse4truefalsefalse2000020000USD$falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 158 -Paragraph 7 -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Amortization of net loss29false 4us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse6300063000USD$falsetruefalse2truefalsefalse6800068000USD$falsetruefalse3truefalsefalse126000126000USD$falsetruefalse4truefalsefalse137000137000USD$falsetruefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 true2Net periodic benefit costfalsePension and Other Postretirement Plans (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.nationalwesternlife.com/role/PensionAndOtherPostretirementPlansDetails629