Schedule II - Condensed Financial Information of Registrant (Parent Company Only) Schedule II - Condensed Financial Information of Registrant - Income Taxes (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Operating Loss Carryforwards	$ 3,744
Minimum [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2029
Maximum [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2040
AFG [Member]
Operating Loss Carryforwards	$ 1,596
AFG [Member] | Minimum [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2029
AFG [Member] | Maximum [Member]
Operating Loss Carryforwards, Expiration Date	Jan. 01, 2034
Ambac Assurance [Member] | Minimum [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2029
Ambac Assurance [Member] | Maximum [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2040