Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The accompanying condensed consolidated financial statements of Torchmark Corporation (Torchmark or alternatively, the Company) have been prepared in accordance with the instructions to Form 10-Q. Therefore, they do not include all of the annual disclosures required by accounting principles generally accepted in the United States of America (GAAP). However, in the opinion of management, these statements include all adjustments, consisting of normal recurring adjustments, which are necessary for a fair presentation of the condensed consolidated financial position at September 30, 2018, and the condensed consolidated results of operations, comprehensive income, and cash flows for the periods ended September 30, 2018 and 2017. The interim period condensed consolidated financial statements should be read in conjunction with the Consolidated Financial Statements that are included in the Form 10-K filed with the Securities Exchange Commission (SEC) on February 26, 2018.
Accounting Pronouncements Adopted / Not Yet Adopted	Accounting Pronouncements Adopted in the Current Year: ASU 2016-01: In January 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which primarily revises the classification and measurement of certain equity investments such that they will be measured at fair value through net income. Additionally, the guidance eliminates the cost method for partnerships and joint ventures and requires these types of investments to be accounted for under the fair value through net income or equity method. This standard became effective for the Company on January 1, 2018. On January 1, 2018, the Company adopted this standard on a modified retrospective basis for two types of investments: equity securities and certain limited partnerships. The adoption resulted in a $4.9 million after-tax positive adjustment to the opening balance of retained earnings. Subsequent to the adoption, the Company elected to measure its investment in certain limited partnerships at fair value in accordance with the fair value option for financial instruments with changes recognized in "Realized Investment Gains (Losses)" in the Condensed Consolidated Statements of Operations. As of September 30, 2018, the fair value balance of the limited partnerships were $108 million. See Note 4—Investments for further discussion. ASU 2016-15: In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments to provide uniformity in the classification of cash receipts and payments recorded in the statement of cash flows including debt prepayment or debt extinguishment costs, settlement of zero-coupon bonds, and proceeds from the settlement of insurance claims. This standard became effective on January 1, 2018 and did not have a significant impact to the classification on the Condensed Statement of Cash Flows. ASU 2016-16: In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfer of Assets Other Than Inventory. This guidance was issued to improve the accounting for income tax consequences of intra-entity transfers of assets other than inventory by allowing the immediate recognition of the current and deferred income tax effects. Current guidance prohibits the recognition of current and deferred income taxes for an intra-entity transfer until the asset has been sold to an outside party. This guidance is applied on a modified retrospective approach and became effective on January 1, 2018. This adoption did not have a significant impact on the financial statements. ASU 2017-07: In March 2017, the FASB issued ASU No. 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. This guidance was issued to simplify the reporting of pension costs by disaggregating the service-cost component from the other components of net benefit costs and reporting it separately on the income statement. The service-cost component is the only component of net benefit cost that will be eligible for capitalization. The guidance became effective on January 1, 2018 with a retrospective transition method for separation of net benefit costs and a prospective transition method for the capitalization of service costs. The Company will record approximately $3.2 million in additional expense to the 2018 Condensed Consolidated Statements of Operations due to the elimination of the ability to capitalize a portion of the benefit costs. For the nine months ended September 30, 2018, the Company recorded $2.4 million in additional expense. ASU 2017-09: In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting. This guidance was issued to provide clarity and guidance regarding changes to the terms or conditions of a share-based payment award that requires an entity to apply modification accounting. It became effective on January 1, 2018. The adoption had no significant impact on the financial statements as modifications to stock compensation are infrequent. ASU 2018-02: In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (AOCI). This guidance was issued to allow the reclassification of taxes from AOCI to retained earnings as a result of the reduction in corporate income tax rates due to the Tax Cuts and Jobs Act of 2017 (Tax Legislation). Current accounting requires the effect of changes in tax rates used to measure deferred tax assets and liabilities to be reported in net income as of the date of enactment even though deferred taxes were previously recognized in AOCI (stranded taxes). This guidance, however, allows a company to elect to reclassify the stranded taxes in AOCI to retained earnings and is effective for years beginning after December 15, 2018, with early adoption permitted. The Company elected to early adopt this guidance resulting in a reclassification of $252 million from AOCI to retained earnings for the period ended December 31, 2017. Accounting Pronouncements Not Yet Adopted ASU 2016-02/ASU 2018-11: In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), with clarification guidance issued in July 2018. The guidance requires lessees to record a right-of-use asset and corresponding lease liability on the balance sheet for all operating leases that do not qualify for the practical expedients allowed for in this standard. Additional qualitative and quantitative disclosures will be required. This standard will become effective for the Company beginning January 1, 2019. The Company plans to adopt the optional transition method allowed for under ASU 2018-11 by not restating comparative periods and recognizing a cumulative-effect adjustment to the opening balance of retained earnings on the period of adoption. The Company is not a lessor. The Company has made significant progress during 2018 and has implemented appropriate solutions to identify and quantify applicable operating leases in accordance with this guidance. The Company is in the process of finalizing the analysis of the impact of the new guidance, but does not expect the adoption to have a significant impact on the financial statements. Refer to Note 15—Commitments and Contingencies of the 2017 10-K for consideration of the noncancelable operating lease commitments. ASU 2016-13: In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments as well as to change the loss impairment methodology for available-for-sale debt securities by use of an allowance rather than a direct write-down. This standard will become effective on January 1, 2020. The applicable section of the standard related to debt securities requires a prospective transition. The Company does not expect the adoption to have a significant impact on the financial statements as we have limited credit losses with respect to our current available-for-sale portfolio. ASU 2017-04: In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This guidance was issued to simplify the subsequent measurement of goodwill through the elimination of Step 2 from the goodwill impairment test which required a hypothetical purchase price allocation. It will become effective on January 1, 2020 and should be applied on a prospective basis. This adoption will not have an impact on the financial statements. ASU 2017-08: In March 2017, the FASB issued ASU No. 2017-08, Receivables—Nonrefundable Fees and Other Costs (Topic 310-20): Premium Amortization on Purchased Callable Debt Securities. This guidance was issued to shorten the amortization period for certain callable debt securities held at a premium. The guidance requires the premium to be amortized to the earliest call date. It will become effective on January 1, 2019 with early adoption permitted, including during interim periods. The adoption is to be applied on a modified retrospective basis through an adjustment to retained earnings. This adoption will not have a significant impact on the financial statements. ASU 2018-12: In August 2018, the FASB issued ASU No. 2018-12, Financial Services - Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts. The guidance was primarily issued to 1) improve the timeliness of recognizing changes in the liability for future policy benefits and modify the rate used to discount future cash flows, 2) simplify and improve the accounting for certain market-based options or guarantees associated with deposit (or account balance) contracts, 3) simplify the amortization of deferred acquisition costs, and 4) improve the effectiveness of the required disclosures. This guidance is effective beginning January 1, 2021, and should be applied on a retrospective basis. Early adoption of the amendments is permitted. ASU 2018-12 will require changes to the Company's actuarial systems and data inputs related to the valuation of the liabilities. The Company is in the process of evaluating the impact this guidance will have on the financial statements and cannot reasonably estimate at this time. ASU 2018-13: In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement. The amendment modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. The revised guidance is effective beginning January 1, 2020. The removed and modified disclosures will be adopted on a retrospective basis and the new disclosures will be adopted on a prospective basis. Early adoption of the amendments is permitted. The Company does not expect the adoption of this guidance to have a material impact on the financial statements. ASU 2018-14: In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20), Changes to the Disclosure Requirements for Defined Benefit Plans. The guidance removes disclosures that are no longer considered cost beneficial, clarifies the specific requirements of disclosures and adds disclosure requirements identified as relevant. This guidance is effective beginning January 1, 2021, and will be applied retrospectively. Early adoption is permitted. The Company does not expect the adoption of this guidance to have a material impact on the financial statements. ASU 2018-15: In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract. The guidance was issued to align the accounting for implementation costs of hosting arrangements, regardless of whether they convey a license to the hosted software. Accordingly, the standard requires the capitalization of implementation costs incurred in a hosting arrangement that is a service contract, similar to the treatment for developed or obtained internal-use software. The guidance is effective beginning January 1, 2020, and the Company plans to apply the standards on a prospective basis. Early adoption of the amendments is also permitted. The Company is in the process of determining the impact this guidance will have on the financial statements.

Accounting Pronouncements Adopted in the Current Year:

ASU 2016-01: In January 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which primarily revises the classification and measurement of certain equity investments such that they will be measured at fair value through net income. Additionally, the guidance eliminates the cost method for partnerships and joint ventures and requires these types of investments to be accounted for under the fair value through net income or equity method. This standard became effective for the Company on January 1, 2018.

On January 1, 2018, the Company adopted this standard on a modified retrospective basis for two types of investments: equity securities and certain limited partnerships. The adoption resulted in a $4.9 million after-tax positive adjustment to the opening balance of retained earnings. Subsequent to the adoption, the Company elected to measure its investment in certain limited partnerships at fair value in accordance with the fair value option for financial instruments with changes recognized in "Realized Investment Gains (Losses)" in the Condensed Consolidated Statements of Operations. As of September 30, 2018, the fair value balance of the limited partnerships were $108 million. See Note 4—Investments for further discussion.

ASU 2016-15: In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments to provide uniformity in the classification of cash receipts and payments recorded in the statement of cash flows including debt prepayment or debt extinguishment costs, settlement of zero-coupon bonds, and proceeds from the settlement of insurance claims. This standard became effective on January 1, 2018 and did not have a significant impact to the classification on the Condensed Statement of Cash Flows.

ASU 2016-16: In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfer of Assets Other Than Inventory. This guidance was issued to improve the accounting for income tax consequences of intra-entity transfers of assets other than inventory by allowing the immediate recognition of the current and deferred income tax effects. Current guidance prohibits the recognition of current and deferred income taxes for an intra-entity transfer until the asset has been sold to an outside party. This guidance is applied on a modified retrospective approach and became effective on January 1, 2018. This adoption did not have a significant impact on the financial statements.

ASU 2017-07: In March 2017, the FASB issued ASU No. 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. This guidance was issued to simplify the reporting of pension costs by disaggregating the service-cost component from the other components of net benefit costs and reporting it separately on the income statement. The service-cost component is the only component of net benefit cost that will be eligible for capitalization. The guidance became effective on January 1, 2018 with a retrospective transition method for separation of net benefit costs and a prospective transition method for the capitalization of service costs. The Company will record approximately $3.2 million in additional expense to the 2018 Condensed Consolidated Statements of Operations due to the elimination of the ability to capitalize a portion of the benefit costs. For the nine months ended September 30, 2018, the Company recorded $2.4 million in additional expense.

ASU 2017-09: In May 2017, the FASB issued ASU No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting. This guidance was issued to provide clarity and guidance regarding changes to the terms or conditions of a share-based payment award that requires an entity to apply modification accounting. It became effective on January 1, 2018. The adoption had no significant impact on the financial statements as modifications to stock compensation are infrequent.

ASU 2018-02: In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (AOCI). This guidance was issued to allow the reclassification of taxes from AOCI to retained earnings as a result of the reduction in corporate income tax rates due to the Tax Cuts and Jobs Act of 2017 (Tax Legislation). Current accounting requires the effect of changes in tax rates used to measure deferred tax assets and liabilities to be reported in net income as of the date of enactment even though deferred taxes were previously recognized in AOCI (stranded taxes). This guidance, however, allows a company to elect to reclassify the stranded taxes in AOCI to retained earnings and is effective for years beginning after December 15, 2018, with early adoption permitted. The Company elected to early adopt this guidance resulting in a reclassification of $252 million from AOCI to retained earnings for the period ended December 31, 2017.

Accounting Pronouncements Not Yet Adopted

ASU 2016-02/ASU 2018-11: In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), with clarification guidance issued in July 2018. The guidance requires lessees to record a right-of-use asset and corresponding lease liability on the balance sheet for all operating leases that do not qualify for the practical expedients allowed for in this standard. Additional qualitative and quantitative disclosures will be required. This standard will become effective for the Company beginning January 1, 2019. The Company plans to adopt the optional transition method allowed for under ASU 2018-11 by not restating comparative periods and recognizing a cumulative-effect adjustment to the opening balance of retained earnings on the period of adoption. The Company is not a lessor.

The Company has made significant progress during 2018 and has implemented appropriate solutions to identify and quantify applicable operating leases in accordance with this guidance. The Company is in the process of finalizing the analysis of the impact of the new guidance, but does not expect the adoption to have a significant impact on the financial statements. Refer to Note 15—Commitments and Contingencies of the 2017 10-K for consideration of the noncancelable operating lease commitments.

ASU 2016-13: In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments as well as to change the loss impairment methodology for available-for-sale debt securities by use of an allowance rather than a direct write-down. This standard will become effective on January 1, 2020. The applicable section of the standard related to debt securities requires a prospective transition. The Company does not expect the adoption to have a significant impact on the financial statements as we have limited credit losses with respect to our current available-for-sale portfolio.

ASU 2017-04: In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This guidance was issued to simplify the subsequent measurement of goodwill through the elimination of Step 2 from the goodwill impairment test which required a hypothetical purchase price allocation. It will become effective on January 1, 2020 and should be applied on a prospective basis. This adoption will not have an impact on the financial statements.

ASU 2017-08: In March 2017, the FASB issued ASU No. 2017-08, Receivables—Nonrefundable Fees and Other Costs (Topic 310-20): Premium Amortization on Purchased Callable Debt Securities. This guidance was issued to shorten the amortization period for certain callable debt securities held at a premium. The guidance requires the premium to be amortized to the earliest call date. It will become effective on January 1, 2019 with early adoption permitted, including during interim periods. The adoption is to be applied on a modified retrospective basis through an adjustment to retained earnings. This adoption will not have a significant impact on the financial statements.

ASU 2018-12: In August 2018, the FASB issued ASU No. 2018-12, Financial Services - Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts. The guidance was primarily issued to 1) improve the timeliness of recognizing changes in the liability for future policy benefits and modify the rate used to discount future cash flows, 2) simplify and improve the accounting for certain market-based options or guarantees associated with deposit (or account balance) contracts, 3) simplify the amortization of deferred acquisition costs, and 4) improve the effectiveness of the required disclosures. This guidance is effective beginning January 1, 2021, and should be applied on a retrospective basis. Early adoption of the amendments is permitted. ASU 2018-12 will require changes to the Company's actuarial systems and data inputs related to the valuation of the liabilities. The Company is in the process of evaluating the impact this guidance will have on the financial statements and cannot reasonably estimate at this time.

ASU 2018-13: In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement. The amendment modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. The revised guidance is effective beginning January 1, 2020. The removed and modified disclosures will be adopted on a retrospective basis and the new disclosures will be adopted on a prospective basis. Early adoption of the amendments is permitted. The Company does not expect the adoption of this guidance to have a material impact on the financial statements.

ASU 2018-14: In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20), Changes to the Disclosure Requirements for Defined Benefit Plans. The guidance removes disclosures that are no longer considered cost beneficial, clarifies the specific requirements of disclosures and adds disclosure requirements identified as relevant. This guidance is effective beginning January 1, 2021, and will be applied retrospectively. Early adoption is permitted. The Company does not expect the adoption of this guidance to have a material impact on the financial statements.

ASU 2018-15: In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract. The guidance was issued to align the accounting for implementation costs of hosting arrangements, regardless of whether they convey a license to the hosted software. Accordingly, the standard requires the capitalization of implementation costs incurred in a hosting arrangement that is a service contract, similar to the treatment for developed or obtained internal-use software. The guidance is effective beginning January 1, 2020, and the Company plans to apply the standards on a prospective basis. Early adoption of the amendments is also permitted. The Company is in the process of determining the impact this guidance will have on the financial statements.