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Investment Securities (Significant Unobservable Inputs) (Details) - NR $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2019 USD ($) | Dec. 31, 2018 USD ($)
Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate |  | 9.00%
Kudu Investments | Discounted cash flow |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 219.3 |
Kudu Investments | Minimum | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 15.00% |
Kudu Investments | Maximum | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 20.00% |
MediaAlpha | Discounted cash flow |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 150.0 |
MediaAlpha | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 17.00% |
MediaAlpha | Long-term revenue growth |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Measurement input | 4.00% |
DavidShield & PassportCard | Discounted cash flow |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 90.0 | $ 75.0
DavidShield & PassportCard | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 18.00% | 18.00%
DavidShield & PassportCard | Revenue exit multiple |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Equity Securities, FV-NI, Measurement Input | 1 | 1
Private Debt Instrument | Discounted cash flow |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 22.7 | $ 10.0
Private Debt Instrument | Minimum | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 6.00% |
Private Debt Instrument | Maximum | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 9.00% |
Elementum Holdings, L.P. | Price of Recent Transaction |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 55.1 |
Other | Discounted cash flow |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 29.3 | $ 30.0
Other | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate | 23.00% | 23.00%
Other | Minimum | Revenue exit multiple |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Equity Securities, FV-NI, Measurement Input | 2 | 2
Other | Maximum | Revenue exit multiple |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Equity Securities, FV-NI, Measurement Input | 4 | 4
Compare.com | Discounted cash flow |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value |  | $ 16.9
Compare.com | Estimated Net Realizable Value |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 2.5 |
Compare.com | Discount rate |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Fair value, discount rate |  | 22.00%
Compare.com | Revenue exit multiple |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Equity Securities, FV-NI, Measurement Input |  | 3
Galvanic Applied Sciences | Multiple of EBITDA |  |
Quantitative information for Level 3 Fair Value Measurements Assets |  |
Assets, fair value | $ 2.7 | $ 3.1
Equity Securities, FV-NI, Measurement Input | 6 | 6

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