Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Employee benefit plans [Line Items]
Recognized contribution expense	$ 20,000,000	$ 20,000,000	$ 20,000,000
U.S.
Employee benefit plans [Line Items]
Number of years of service to become fully vested	1 year
401 (k) Plan | U.S.
Employee benefit plans [Line Items]
Percentage by which employer contribution matches up to 6% of participant's compensation	100.00%
Maximum percentage of participant's compensation eligible for employer contribution match	7.00%	7.00%	7.00%
Core contribution made by the company as a percentage of participant's compensation	7.00%	7.00%	7.00%
Nonqualified Supplemental Executive Retirement Plan | U.S.
Employee benefit plans [Line Items]
Percentage by which employer contribution matches up to 6% of participant's compensation	100.00%
Maximum percentage of participant's compensation eligible for employer contribution match	6.00%
Core contribution made by the company as a percentage of participant's compensation	6.00%
Restricted Stock Units (RSUs)
Employee benefit plans [Line Items]
Unrecognized compensation expense	$ 21,000,000
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	1 year 9 months 18 days
Total fair value of awards delivered	$ 12,000,000	$ 12,000,000	$ 11,000,000
Granted (in dollars per share)	$ 56.46	$ 44.08	$ 41.31
Restricted Stock Units (RSUs) | Minimum
Employee benefit plans [Line Items]
Vesting period of awards (in years)	3 years
Restricted Stock Units (RSUs) | Maximum
Employee benefit plans [Line Items]
Vesting period of awards (in years)	4 years
Performance Restricted Stock Units
Employee benefit plans [Line Items]
Unrecognized compensation expense	$ 15,000,000
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	1 year 8 months 12 days
Total fair value of awards delivered	$ 8,000,000	$ 9,000,000	$ 8,000,000
Granted (in dollars per share)	$ 62.89	$ 41.34
Number of shares issued per right (in shares)	2
Vesting period of awards (in years)	3 years
Performance Restricted Stock Units, Tied to Relative TSR
Employee benefit plans [Line Items]
Granted (in dollars per share)	$ 62.89	52.04	$ 41.03
Number of shares issued per right (in shares)	2.5
Restricted Stock Awards
Employee benefit plans [Line Items]
Unrecognized compensation expense	$ 700,000
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	3 months 18 days
Granted (in dollars per share)	$ 59.47	$ 51.34	$ 28.12
Total fair value of awards vested	$ 2,300,000	$ 1,900,000	$ 2,300,000
Assured Guaranty Ltd. 2004 Long-Term Incentive Plan
Employee benefit plans [Line Items]
Maximum number of common shares that may be delivered (in shares)	18,670,000
Assured Guaranty Ltd. 2004 Long-Term Incentive Plan | Stock Options
Employee benefit plans [Line Items]
Number of common shares available for grant (in shares)	8,059,991
Employee Stock Purchase Plan | Employee Stock
Employee benefit plans [Line Items]
Number of common shares available for grant (in shares)	65,042
Value of shares that can be purchased as a percentage of participant's compensation	10.00%
Value of shares that can be purchased	$ 25,000
Purchase price of shares as a percentage of the fair market value of the stock	85.00%
Capital shares reserved for future issuance (in shares)	850,000