Reinsurance Reinsurance (Ceded Reinsurance Receivable Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 2,580	$ 983
Reinsurance Recoverables, Percentage of Total	100.00%	100.00%
Other Reinsurers [Member] | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 174	$ 182
Reinsurance Recoverables, Percentage of Total	6.80%	18.50%
AM Best, A+ Rating [Member] | Reinsurer A [Member] | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 1,626	$ 0
Reinsurance Recoverables, Percentage of Total	63.00%	0.00%
AM Best, A+ Rating [Member] | Reinsurer B [Member] | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 423	$ 420
Reinsurance Recoverables, Percentage of Total	16.40%	42.70%
AM Best, A+ Rating [Member] | Reinsurer C [Member] | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 212	$ 216
Reinsurance Recoverables, Percentage of Total	8.20%	22.00%
AM Best, A+ Rating [Member] | Reinsurer E [Member] | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 44	$ 46
Reinsurance Recoverables, Percentage of Total	1.70%	4.70%
AM Best, A Rating [Member] | Reinsurer D [Member] | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 59	$ 64
Reinsurance Recoverables, Percentage of Total	2.30%	6.50%
AM Best, A++ Rating [Member] | Reinsurer F | Customer Concentration Risk | Reinsurance Ceded Receivables Benchmark
Ceded Credit Risk [Line Items]
Reinsurance ceded receivables and other	$ 42	$ 55
Reinsurance Recoverables, Percentage of Total	1.60%	5.60%