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Investment Securities - Significant Unobservable Inputs (Details) $ / shares in Units, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2021 USD ($) $ / shares | Mar. 31, 2020 USD ($) | Dec. 31, 2020 USD ($) $ / shares
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Investments in kudu participation contracts | $ 11.0 | $ 21.0 |
Kudu Investments | Minimum | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 18.00% |  | 18.00%
Kudu Investments | Minimum | Terminal Multiple | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Terminal Cash Flow Exit Multiple | 7 |  | 7
Kudu Investments | Maximum | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 23.00% |  | 23.00%
Kudu Investments | Maximum | Terminal Multiple | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Terminal Cash Flow Exit Multiple | 12 |  | 12
PassportCard/DavidShield |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Investments in kudu participation contracts |  |  | $ 15.0
Private debt instruments | Minimum | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 4.00% |  | 4.00%
Private debt instruments | Maximum | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 8.00% |  | 8.00%
All other | Minimum | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 20.00% |  | 20.00%
All other | Maximum | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 24.00% |  | 24.00%
New Market Solutions, LLC | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Share price (in USD per share) | $ / shares | $ 9.9 |  |
Zillion Insurance Services |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Investments in kudu participation contracts |  |  | $ 2.5
Kudu |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Investments in kudu participation contracts | $ 10.9 |  | 118.2
Level 3 | Kudu Investments | Standard Poors NR Rating | Discounted cash flow |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | 427.4 |  | 400.6
Level 3 | PassportCard/DavidShield | Standard Poors NR Rating | Discounted cash flow |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 95.0 |  | $ 95.0
Level 3 | PassportCard/DavidShield | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 23.00% |  | 23.00%
Level 3 | PassportCard/DavidShield | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Terminal Revenue Growth Rate | 4.00% |  | 4.00%
Level 3 | Elementum Holdings L.P. | Standard Poors NR Rating | Discounted cash flow |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 56.7 |  | $ 55.1
Level 3 | Elementum Holdings L.P. | Discount rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Fair value, discount rate | 17.00% |  | 17.00%
Level 3 | Elementum Holdings L.P. | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Terminal Revenue Growth Rate | 4.00% |  | 4.00%
Level 3 | Private debt instruments | Standard Poors NR Rating | Discounted cash flow |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 17.0 |  | $ 17.1
Level 3 | All other | Standard Poors NR Rating | Discounted cash flow |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 19.8 |  | $ 18.8
Level 3 | All other | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Terminal Revenue Growth Rate | 4.00% |  | 4.00%
Level 3 | New Market Solutions, LLC | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 9.9 |  | $ 9.9
Level 3 | New Market Solutions, LLC | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Share price (in USD per share) | $ / shares |  |  | $ 9.9
Level 3 | Noblr, Inc. | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 8.7 |  | $ 8.7
Level 3 | Noblr, Inc. | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Share price (in USD per share) | $ / shares | $ 8.7 |  |
Level 3 | Noblr, Inc. | Recent Transaction | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Share price (in USD per share) | $ / shares |  |  | $ 8.7
Level 3 | Zillion Insurance Services | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value |  |  | $ 5.0
Level 3 | Zillion Insurance Services | Measurement Input, Long-term Revenue Growth Rate | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 5.0 |  |
Level 3 | Zillion Insurance Services | Recent Transaction | Standard Poors NR Rating |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value |  |  | $ 5.0
Level 3 | Zillion Insurance Services | Zillion Insurance Services | Standard Poors NR Rating | Recent Transaction |  |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |  |
Assets, fair value | $ 5.0 |  |

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