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Debt Summary of Obligations (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Aug. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Debt Instrument [Line Items] |  |  |
Long-term debt, carrying value | $ 1,243.2 |  | $ 832.8
Federal Home Loan Bank Advances (FHLB) |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, carrying value | $ 155.0 |  | 155.0
Stated interest rate (in hundredths) | 1.91% |  |
Senior Notes | 5.75% Senior Notes due 2023 |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, carrying value | $ 240.6 |  | 420.9
Stated interest rate (in hundredths) | 5.75% |  |
Debt instrument, face amount | $ 242.3 |  |
Senior Notes | 5.25% Senior Notes due 2028 |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, carrying value | $ 638.8 |  | 0.0
Stated interest rate (in hundredths) | 5.25% | 5.25% |
Debt instrument, face amount | $ 650.0 | $ 650.0 |
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063 |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, carrying value | $ 208.8 |  | $ 256.9
Stated interest rate (in hundredths) | 9.00% |  |

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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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