The amount of the variable interest entity's revenues consolidated into the statement of income, including interest income, net realized and unrealized gains (losses) on assets, and other income, net of the amount of the variable interest entity's expenses consolidated into the statement of income, including interest expense, net realized and unrealized gains (losses) on liabilities with and without recourse, and other expenses.

No definition available.

Variable Interest Entities - Narrative (Details)	1 Months Ended	3 Months Ended		12 Months Ended
Variable Interest Entities - Narrative (Details)	Feb. 28, 2017 USD ($)	Mar. 31, 2020 USD ($) policy Entity	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) policy Entity
Variable Interest Entity [Line Items]
Total shareholders’ equity attributable to Assured Guaranty Ltd.		$ 6,240,000,000		$ 6,639,000,000
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt		0
Fair value gains (losses) on FG VIEs		(9,000,000)	$ 5,000,000
Variable Interest Entity, Other Consolidated [Abstract]
Other consolidated VIE assets		93,000,000		91,000,000
Other consolidated VIE liabilities		$ 23,000,000		$ 12,000,000
Number of Policies Monitored \| policy		18,000
Number of Policies Monitored, Not Within the Scope of ASC 810 \| policy		16,000
Number of Policies that Contain Provisions for Consolidation \| policy		87		90
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total shareholders’ equity attributable to Assured Guaranty Ltd.		$ 8,000,000		$ (1,000,000)
Fair value gains (losses) on FG VIEs		$ (9,000,000)	5,000,000
Variable Interest Entity, Other Consolidated [Abstract]
Number of Entities Consolidated \| Entity		26		27
FG VIE matured, number \| Entity		1
Residential Mortgage Backed Securities and Other Insurance Products [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Change in the instrument specific credit risk of the VIEs' assets		$ 3,000,000	$ 6,000,000
Future Equity Investments [Member]
Variable Interest Entity [Line Items]
Long-term purchase commitment, amount	$ 100,000,000
Future Equity Investments [Member] \| Maximum [Member]
Variable Interest Entity, Other Consolidated [Abstract]
Investment Company, Committed Capital		17,000,000
Future Equity Investments [Member] \| AGL Subsidiaries [Member] \| Assured Investment Management Funds [Member] \| Maximum [Member]
Variable Interest Entity [Line Items]
Long-term purchase commitment, amount		500,000,000		$ 500,000,000
Equity Method Investments [Member] \| AGL Subsidiaries [Member] \| Assured Investment Management Funds [Member] \| Maximum [Member]
Variable Interest Entity [Line Items]
Long-term purchase commitment, amount		192,000,000		79,000,000
Variable Interest Entity, Other Consolidated [Abstract]
Long-term purchase commitment fair value		179,000,000		$ 77,000,000
Consolidated Investment Vehicles [Member]
Variable Interest Entity [Line Items]
Fair value gains (losses) on FG VIEs		$ 12,000,000