Claim and Claim Adjustment Expense Reserves - A&EP Reserves (Details) - A&EP Reserves - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2010	Dec. 31, 2021
A&EP Reserves [Abstract]
Net A&EP claim and allocated claim adjustment expense reserves					$ 1,600
Aggregate limit under A&EP Loss Portfolio Transfer					4,000
Ceded A&EP claim and allocated claim adjustment expense reserves under existing third party reinsurance contracts transferred to NICO under A&EP Loss Portfolio Transfer					1,200
Reinsurance premium paid to NICO under A&EP loss portfolio transfer					2,000
Net reinsurance receivables transferred to NICO under A&EP Loss Portfolio Transfer					215
Total consideration					$ 2,200
Retroactive reinsurance benefit recognized	$ 11	$ 12	$ 23	$ 22
Cumulative amounts ceded under loss portfolio transfer	3,400		3,400			$ 3,400
Unrecognized deferred retroactive reinsurance benefit	406		406			$ 429
Fair value of collateral trust account	$ 2,400		$ 2,400