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Investment Securities - Significant Unobservable Inputs (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Other long-term investments | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 41.1 | $ 46.7
Kudu Participation Contracts | Kudu |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Investments in trading securities | $ 99.8 | $ 223.4
Measurement Input, Discount Rate | Kudu's Participation Contracts | Standard Poors NR Rating |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, pretax discount rate | 21.00% | 20.00%
Measurement Input, Discount Rate | Kudu's Participation Contracts | Standard Poors NR Rating | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate (as a percent) | 18.00% | 18.00%
Measurement Input, Discount Rate | Kudu's Participation Contracts | Standard Poors NR Rating | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate (as a percent) | 25.00% | 23.00%
Measurement Input, Discount Rate | PassportCard/DavidShield | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate (as a percent) | 24.00% | 23.00%
Measurement Input, Discount Rate | Elementum Holdings, L.P. | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate (as a percent) | 21.00% | 17.00%
Measurement Input, Discount Rate | Private debt instruments | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate (as a percent) | 11.00% | 8.00%
Measurement Input, Long-term Revenue Growth Rate | PassportCard/DavidShield | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Terminal revenue growth rate (as a percent) | 4.00% | 4.00%
Measurement Input, Long-term Revenue Growth Rate | Elementum Holdings, L.P. | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Terminal revenue growth rate (as a percent) | 4.00% | 4.00%
Terminal Multiple | Kudu's Participation Contracts | Standard Poors NR Rating |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Cash flow exit multiple, pretax | 11.8 | 10.0
Terminal Multiple | Kudu's Participation Contracts | Standard Poors NR Rating | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Cash flow exit multiple | 7 | 7
Terminal Multiple | Kudu's Participation Contracts | Standard Poors NR Rating | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Cash flow exit multiple | 16 | 13
Discounted Cash Flow Valuation Technique | Kudu's Participation Contracts | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 695.9 | $ 669.5
Discounted Cash Flow Valuation Technique | PassportCard/DavidShield | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | 135.0 | 120.0
Discounted Cash Flow Valuation Technique | Elementum Holdings, L.P. | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | 30.0 | 45.0
Discounted Cash Flow Valuation Technique | Private debt instruments | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | 9.6 | 9.4
Probability Weighted Expected Return Method | Kudu's Participation Contracts | Standard Poors NR Rating | Level 3 |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 189.0 | $ 78.8

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