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Fair Value of Financial Instruments - Financial Instruments Measured and Carried at Fair Value (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Mar. 31, 2018 | Dec. 31, 2017 | Mar. 31, 2017 | Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | $ 1,356 | $ 4,739 | $ (110) | $ 5,935 |  |  |  |
Net unrealized investment gains (losses) included in other comprehensive income | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 | 0 | 0 |  |  |  |
Purchases | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 | 0 | 0 |  |  |  |
Issuances | 2,107 | 3,397 | 3,439 | 6,786 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 271,651 | 246,505 | 271,651 | 246,505 | $ 243,868 | $ 230,257 | $ 248,757 | $ 212,104
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value | 77,788 | 67,995 | 77,788 | 67,995 | 78,486 | 80,733 | 64,261 | 59,393
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 48,031 | 11,483 | 73,631 | 61,654 |  |  |  |
Transfers into Level 3 | 0 | 0 | 0 | 0 |  |  |  |
Net realized investment gains (losses) included in net income related to financial assets | (246) | (1,714) | (243) | (1,714) |  |  |  |
Net realized gains (losses) included in net income related to financial liabilities | (1,291) | 1,238 | (3,513) | 3,546 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 15,509 | 11,410 | 15,509 | 18,271 |  |  |  |
Transfers out of Level 3 | 0 | 0 | 0 | 0 |  |  |  |
Financial Liabilities |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 | 3 | 0 |  |  |  |
Sales | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 | 0 | 0 |  |  |  |
Settlements | 0 | 0 | 0 | 0 |  |  |  |
FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPaydownsAndMaturities | 1,514 | 901 | 2,871 | 1,730 |  |  |  |
Paydowns, maturities and distributions | 5,849 | 5,350 | 16,372 | 13,203 |  |  |  |
Short-term investments |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 751
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 | 0 | 0 | 0 |  |  |  |
Net realized investment gains (losses) included in net income related to financial assets | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 0 | 0 | 751 |  |  |  |
Financial Liabilities |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 | 0 | 0 |  |  |  |
Paydowns, maturities and distributions | 0 | 0 | 0 | 0 |  |  |  |
Municipal bonds |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 397 | 1,287 | 840 | 3,158 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 49,921 | 49,123 | 49,921 | 49,123 | 49,748 | 49,328 | 53,462 | 46,497
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 | 0 | 0 | 5,214 |  |  |  |
Net realized investment gains (losses) included in net income related to financial assets | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 5,557 | 0 | 5,557 |  |  |  |
Financial Liabilities |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 | 0 | 0 |  |  |  |
Paydowns, maturities and distributions | 224 | 69 | 247 | 189 |  |  |  |
Corporate bonds |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | (700) | 359 | (1,587) | 455 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 92,663 | 77,052 | 92,663 | 77,052 | 78,780 | 72,979 | 82,495 | 60,191
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 29,709 | 2,001 | 40,487 | 31,919 |  |  |  |
Net realized investment gains (losses) included in net income related to financial assets | (246) | 0 | (246) | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 11,279 | 5,853 | 11,279 | 11,963 |  |  |  |
Financial Liabilities |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 | 0 | 0 |  |  |  |
Paydowns, maturities and distributions | 3,601 | 1,950 | 7,691 | 3,550 |  |  |  |
Equity securities |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 | 0 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 6 | 6 | 6 | 6 | $ 6 | 6 | $ 6 | $ 6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 | 0 | 0 | 0 |  |  |  |
Net realized investment gains (losses) included in net income related to financial assets | 0 | 0 | 3 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 0 | 0 | 0 |  |  |  |
Financial Liabilities |  |  |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 | 3 | 0 |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 | 0 | 0 |  |  |  |
Paydowns, maturities and distributions | 0 | $ 0 | 0 | $ 0 |  |  |  |
Carrying Amount |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 7,804,718 |  | 7,804,718 |  |  | 7,950,184 |  |
Financial Liabilities |  |  |  |  |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 486 |  | 486 |  |  | 594 |  |
Other policyholder funds, embedded derivatives | 77,788 |  | 77,788 |  |  | 80,733 |  |
Carrying Amount | Recurring |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 7,475,565 |  | 7,475,565 |  |  | 7,724,075 |  |
Carrying Amount | Short-term investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 176,497 |  | 176,497 |  |  | 62,593 |  |
Carrying Amount | Mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 707,324 |  | 707,324 |  |  | 696,725 |  |
Carrying Amount | Other, including U.S. Treasury securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 782,223 |  | 782,223 |  |  | 735,408 |  |
Carrying Amount | Municipal bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 1,827,511 |  | 1,827,511 |  |  | 1,893,253 |  |
Carrying Amount | Foreign government bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 95,505 |  | 95,505 |  |  | 102,738 |  |
Carrying Amount | Corporate bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 2,397,724 |  | 2,397,724 |  |  | 2,578,954 |  |
Carrying Amount | Other mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 1,665,278 |  | 1,665,278 |  |  | 1,716,997 |  |
Carrying Amount | Equity securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 130,780 |  | 130,780 |  |  | 135,466 |  |
Carrying Amount | Other investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 21,876 |  | 21,876 |  |  | 28,050 |  |
Fair Value |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 7,804,718 |  | 7,804,718 |  |  | 7,950,184 |  |
Financial Liabilities |  |  |  |  |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 486 |  | 486 |  |  | 594 |  |
Other policyholder funds, embedded derivatives | 77,788 |  | 77,788 |  |  | 80,733 |  |
Fair Value | Recurring |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 7,475,565 |  | 7,475,565 |  |  | 7,724,075 |  |
Fair Value | Short-term investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 176,497 |  | 176,497 |  |  | 62,593 |  |
Fair Value | Mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 707,324 |  | 707,324 |  |  | 696,725 |  |
Fair Value | Other, including U.S. Treasury securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 782,223 |  | 782,223 |  |  | 735,408 |  |
Fair Value | Municipal bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 1,827,511 |  | 1,827,511 |  |  | 1,893,253 |  |
Fair Value | Foreign government bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 95,505 |  | 95,505 |  |  | 102,738 |  |
Fair Value | Corporate bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 2,397,724 |  | 2,397,724 |  |  | 2,578,954 |  |
Fair Value | Other mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 1,665,278 |  | 1,665,278 |  |  | 1,716,997 |  |
Fair Value | Equity securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 130,780 |  | 130,780 |  |  | 135,466 |  |
Fair Value | Other investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 21,876 |  | 21,876 |  |  | 28,050 |  |
Fair Value | Level 1 |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 283,331 |  | 283,331 |  |  | 172,539 |  |
Financial Liabilities |  |  |  |  |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 0 |  | 0 |  |  | 0 |  |
Other policyholder funds, embedded derivatives | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 1 | Recurring |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 26,598 |  | 26,598 |  |  | 27,738 |  |
Fair Value | Level 1 | Short-term investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 176,497 |  | 176,497 |  |  | 62,593 |  |
Fair Value | Level 1 | Mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 1 | Other, including U.S. Treasury securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 13,201 |  | 13,201 |  |  | 13,393 |  |
Fair Value | Level 1 | Municipal bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 1 | Foreign government bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 1 | Corporate bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 13,397 |  | 13,397 |  |  | 14,345 |  |
Fair Value | Level 1 | Other mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 1 | Equity securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 80,236 |  | 80,236 |  |  | 82,208 |  |
Fair Value | Level 1 | Other investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 2 |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 7,249,736 |  | 7,249,736 |  |  | 7,547,388 |  |
Financial Liabilities |  |  |  |  |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 486 |  | 486 |  |  | 594 |  |
Other policyholder funds, embedded derivatives | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 2 | Recurring |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 7,177,322 |  | 7,177,322 |  |  | 7,466,086 |  |
Fair Value | Level 2 | Short-term investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 2 | Mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 703,543 |  | 703,543 |  |  | 693,375 |  |
Fair Value | Level 2 | Other, including U.S. Treasury securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 769,022 |  | 769,022 |  |  | 722,015 |  |
Fair Value | Level 2 | Municipal bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 1,777,590 |  | 1,777,590 |  |  | 1,843,925 |  |
Fair Value | Level 2 | Foreign government bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 95,505 |  | 95,505 |  |  | 102,738 |  |
Fair Value | Level 2 | Corporate bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 2,291,664 |  | 2,291,664 |  |  | 2,491,630 |  |
Fair Value | Level 2 | Other mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 1,539,998 |  | 1,539,998 |  |  | 1,612,403 |  |
Fair Value | Level 2 | Equity securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 50,538 |  | 50,538 |  |  | 53,252 |  |
Fair Value | Level 2 | Other investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 21,876 |  | 21,876 |  |  | 28,050 |  |
Fair Value | Level 3 |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 271,651 |  | 271,651 |  |  | 230,257 |  |
Financial Liabilities |  |  |  |  |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 0 |  | 0 |  |  | 0 |  |
Other policyholder funds, embedded derivatives | 77,788 |  | 77,788 |  |  | 80,733 |  |
Fair Value | Level 3 | Recurring |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 271,645 |  | 271,645 |  |  | 230,251 |  |
Fair Value | Level 3 | Short-term investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 3 | Mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 3,781 |  | 3,781 |  |  | 3,350 |  |
Fair Value | Level 3 | Other, including U.S. Treasury securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 3 | Municipal bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 49,921 |  | 49,921 |  |  | 49,328 |  |
Fair Value | Level 3 | Foreign government bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 0 |  | 0 |  |  | 0 |  |
Fair Value | Level 3 | Corporate bonds |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 92,663 |  | 92,663 |  |  | 72,979 |  |
Fair Value | Level 3 | Other mortgage-backed securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 125,280 |  | 125,280 |  |  | 104,594 |  |
Fair Value | Level 3 | Equity securities |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | 6 |  | 6 |  |  | 6 |  |
Fair Value | Level 3 | Other investments |  |  |  |  |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |  |  |  |  |
Investments | $ 0 |  | $ 0 |  |  | $ 0 |  |

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- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset paydowns and maturities. + References No definition available. + Details
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- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Paydowns And Maturities + References No definition available. + Details
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Namespace Prefix: | hmn_
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- Definition Fair value disclosure of accrued obligation to policyholders that relates to insured events under other insurance contracts. + References No definition available. + Details
Name: | hmn_LiabilityForFuturePolicyBenefitsDerivativeInstrumentsFairValueDisclosure
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
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