Schedule I - Condensed Financial Information of Parent - Condensed Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	$ 7,344	$ 6,554	$ 2,820
INVESTING ACTIVITIES:
Acquisitions	0	0	(1,185)
Other investing activities	3	(15)	0
Net cash provided by (used in) investing activities	1,486	(518)	(998)
FINANCING ACTIVITIES:
Proceeds from the issuance of long-term debt	1,893	3,621	2,015
Payments on maturity and redemption of debt	(500)	(1,880)	(3,068)
Payments for repurchase of common stock	(10,377)	(6,621)	(163)
Proceeds from exercise of stock options	134	7	5
Other financing activities	(59)	(24)	(28)
Net cash used in financing activities	(8,909)	(4,897)	(1,239)
Net (decrease) increase in cash and cash equivalents	(116)	1,099	570
Total cash and cash equivalents and restricted cash and cash equivalents, beginning of period	12,251	11,152	10,582
Total cash and cash equivalents and restricted cash and cash equivalents, end of period	12,135	12,251	11,152
Parent Company
OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	6,464	3,695	(250)
INVESTING ACTIVITIES:
Proceeds from internal transfers of subsidiaries	0	174	522
Acquisitions	0	0	(1,296)
Dividends received	107	3,087	72
Other investing activities	(128)	(102)	(88)
Net cash provided by (used in) investing activities	(21)	3,159	(790)
FINANCING ACTIVITIES:
Proceeds from the issuance of long-term debt	1,893	3,621	2,015
Payments on maturity and redemption of debt	(500)	(1,880)	(3,068)
Payments for repurchase of common stock	(10,377)	(6,621)	(163)
Proceeds from exercise of stock options	134	7	5
Other financing activities	49	47	(115)
Net cash used in financing activities	(8,801)	(4,826)	(1,326)
Net (decrease) increase in cash and cash equivalents	(2,358)	2,028	(2,366)
Total cash and cash equivalents and restricted cash and cash equivalents, beginning of period	4,110	2,082	4,448
Total cash and cash equivalents and restricted cash and cash equivalents, end of period	$ 1,752	$ 4,110	$ 2,082