Temporarily Impaired Available for Sale Debt Securities by Time Period Impaired (Details) - USD ($) $ in Millions	Apr. 01, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 1,471	$ 3,856
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17	201
Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	7,238	4,642
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	690	633
Unrealized Loss Position, Fair Value	8,709	8,498
Unrealized Loss Position, Accumulated Loss	707	834
Taxable bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,303	3,705
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15	199
Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	7,223	4,627
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	688	631
Unrealized Loss Position, Fair Value	8,526	8,332
Unrealized Loss Position, Accumulated Loss	703	830
Restricted investments [Member]
Debt Securities, Available-for-sale [Line Items]
Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	168	151
Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	2
Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	15	15
Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	2
Unrealized Loss Position, Fair Value	183	166
Unrealized Loss Position, Accumulated Loss	$ 4	$ 4