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Municipal Bond Guarantee - Schedule of Net Written Premiums (Details) - HG/BAM - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Gross written premiums	$ 3.9	$ 10.9	$ 28.9	$ 42.0
Assumed (ceded) written premiums	0.0	0.0	0.0
Net written premiums	$ 3.9	$ 10.9	$ 28.9	$ 42.0

X

- Definition

Amount of written premiums ceded to other entities.

+ References

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-Publisher FASB
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Amount of direct and assumed premiums written.

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Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums written.

+ References

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-Publisher FASB
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-SubTopic 605
-Section 50
-Paragraph 1
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