Reserve for Unpaid Losses and Loss Adjustment Expenses - Discounted Reserves, Group (Details) - Group Benefits - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Weighted Average Discount Rate [Line Items]
Liability for unpaid losses and loss adjustment expenses, at undiscounted amounts	$ 8,176	$ 8,380	$ 8,636
Discount	(1,304)	(1,353)	(1,401)
Carrying value of liability for unpaid losses and loss adjustment expenses	$ 6,872	$ 7,027	$ 7,235
Minimum
Weighted Average Discount Rate [Line Items]
Weighted average discount rate	2.10%	2.10%	2.10%
Maximum
Weighted Average Discount Rate [Line Items]
Weighted average discount rate	8.00%	8.00%	8.00%
Weighted Average Expected Life
Weighted Average Discount Rate [Line Items]
Weighted average discount rate	3.30%	3.40%	3.40%