Outstanding Exposure - Additional Information (Details) - USD ($) $ in Millions		6 Months Ended
	Jun. 26, 2023	Jun. 30, 2023	Jul. 28, 2023	Jun. 23, 2023	Dec. 31, 2022
Schedule of Insured Financial Obligations [Line Items]
Loss Mitigation Securities		$ 1,300			$ 1,300
Net par outstanding		244,013			233,258
Guarantor, maximum exposure		1,600
Subsequent Event
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding			$ 108
Puerto Rico Electric Power Authority
Schedule of Insured Financial Obligations [Line Items]
Plaintiff debt capacity				$ 2,500
Plaintiff debt capacity allocated to settling creditors				1,400
Plaintiff debt capacity allocated to bondholders and general unsecured creditors				$ 1,100
Claim received as restructuring bonds, percent				12.50%
Puerto Rico Electric Power Authority | Guarantee Obligations
Schedule of Insured Financial Obligations [Line Items]
Damages sought, estimate	$ 2,400
Calculated collection period	100 years
Calculated discount rate	7.00%
Calculated discounted cash flows	$ 3,000
Additional calculated riscount rate	20.00%
Damages sought	$ 8,500
Puerto Rico
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		1,349			1,361
Puerto Rico | Other Public Corporations
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		125
Puerto Rico | PRHTA
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		475
Public finance
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		233,981			224,099
Structured finance
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		10,032			9,159
Commitment to Provide Guarantees | Public finance
Schedule of Insured Financial Obligations [Line Items]
Outstanding commitments to provide guaranties		2,000
Commitment to Provide Guarantees | Structured finance
Schedule of Insured Financial Obligations [Line Items]
Outstanding commitments to provide guaranties		$ 1,300
BIG
Schedule of Insured Financial Obligations [Line Items]
Maximum period of liquidity claims (in years)		1 year
Net par outstanding		$ 5,634			5,892
Residual value insurance policies exposure downgraded		144			144
Net Exposure		84			84
BIG | Puerto Rico
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		1,300			1,400
BIG | Public finance
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		4,566			4,777
BIG | Structured finance
Schedule of Insured Financial Obligations [Line Items]
Net par outstanding		$ 1,068			$ 1,115
Minimum
Schedule of Insured Financial Obligations [Line Items]
Probability of paying more claims than being reimbursed (as a percent)		50.00%