Financial Guarantee Insurance Contracts Earned Premiums by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Premiums Earned, Net, Financial Guarantee Insurance Contracts	$ 7,833	$ 25,836	$ 35,591	$ 56,719
United States [Member] \| Reportable Geographical Components [Member]
Premiums Earned, Net, Financial Guarantee Insurance Contracts	5,626	19,752	33,869	44,469
United Kingdom [Member] \| Reportable Geographical Components [Member]
Premiums Earned, Net, Financial Guarantee Insurance Contracts	4,224	4,958	8,415	9,815
Other International [Member] \| Reportable Geographical Components [Member]
Premiums Earned, Net, Financial Guarantee Insurance Contracts	$ (2,017)	$ 1,126	$ (6,693)	$ 2,435

Amount, after premiums ceded to other entities and premiums assumed by the entity, of financial guarantee premiums earned.

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