Reinsurance - Narrative (Details) - USD ($)	12 Months Ended		24 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Jan. 01, 2018
Assured Guaranty Re [Member]
Ceded Credit Risk [Line Items]
Amounts could be required to pay if third party exercised right to recapture business	$ 40,000,000
AGC [Member]
Ceded Credit Risk [Line Items]
Amounts could be required to pay if third party exercised right to recapture business	287,000,000
Excess of Loss Reinsurance Facility [Member] | AGM, AGC and MAC [Member]
Ceded Credit Risk [Line Items]
Amount of losses covered under the facility				$ 400,000,000
Reinsurance retention policy, excess retention, amount reinsured			$ 180,000,000
Premiums paid during the period	3,200,000	$ 3,200,000
Standard & Poor's, A Rating [Member] | Uncollateralized [Member]
Ceded Credit Risk [Line Items]
Guaranty Liabilities	100,000		100,000
AM Best, A- Rating [Member] | Uncollateralized [Member]
Ceded Credit Risk [Line Items]
Guaranty Liabilities	$ 14,000,000		$ 14,000,000