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Municipal Bond Guarantee - Schedule of Net Written Premiums (Details) - HG/BAM - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |
Direct written premiums | $ 12.5 | $ 18.6 | $ 20.4 | $ 25.0
Assumed written premiums | 0.0 | 0.0 | 0.0 | 0.0
Gross written premiums | 12.5 | 18.6 | 20.4 | 25.0
Direct premiums earned | 3.8 | 3.4 | 7.5 | 6.4
Assumed premiums earned | 0.5 | 0.0 | 1.0 | 0.0
Gross earned premiums | $ 4.3 | $ 3.4 | $ 8.5 | $ 6.4

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