Significant Accounting Policies - Changes in balances of long-duration insurance liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
Large Case Pensions
Present value of expected future policy benefits
Balance at December 31, 2020, net of reinsurance	$ 2,185		$ 2,496		$ 3,647
Add: Reinsurance recoverable	0		0		0
Effect of changes in cash flow assumptions		$ 0		$ 0
Liability for future policy benefits, end of period - current discount rate	2,185	2,253	2,496	3,034	3,647
Large Case Pensions | As Reported
Present value of expected future policy benefits
Balance at December 31, 2020, net of reinsurance					3,224
Add: Reinsurance recoverable					0
Liability for future policy benefits, beginning of period - current discount rate					3,224
Large Case Pensions | Change in discount rate assumptions
Present value of expected future policy benefits
Effect of changes in cash flow assumptions					604
Large Case Pensions | Removal of shadow adjustments in accumulated other comprehensive income
Present value of expected future policy benefits
Effect of changes in cash flow assumptions					(181)
Long-Term Care
Present value of expected future policy benefits
Balance at December 31, 2020, net of reinsurance	1,302		1,361		1,695
Add: Reinsurance recoverable	0		0		0
Effect of changes in cash flow assumptions		0		98
Liability for future policy benefits, end of period - current discount rate	$ 1,596	$ 1,566	$ 1,681	$ 1,991	1,695
Long-Term Care | As Reported
Present value of expected future policy benefits
Balance at December 31, 2020, net of reinsurance					1,142
Add: Reinsurance recoverable					0
Liability for future policy benefits, beginning of period - current discount rate					1,142
Long-Term Care | Change in discount rate assumptions
Present value of expected future policy benefits
Effect of changes in cash flow assumptions					553
Long-Term Care | Removal of shadow adjustments in accumulated other comprehensive income
Present value of expected future policy benefits
Effect of changes in cash flow assumptions					0
Other
Present value of expected future policy benefits
Balance at December 31, 2020, net of reinsurance					490
Add: Reinsurance recoverable					308
Liability for future policy benefits, end of period - current discount rate					798
Other | As Reported
Present value of expected future policy benefits
Balance at December 31, 2020, net of reinsurance					480
Add: Reinsurance recoverable					274
Liability for future policy benefits, beginning of period - current discount rate					754
Other | Change in discount rate assumptions
Present value of expected future policy benefits
Effect of changes in cash flow assumptions					44
Other | Removal of shadow adjustments in accumulated other comprehensive income
Present value of expected future policy benefits
Effect of changes in cash flow assumptions					$ 0