Revision of Prior Period Financial Statements - Schedule of Consolidated Income (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended					6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2023	Sep. 30, 2023	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Labor and Fringe	$ 805	$ 814	$ 761	$ 748	$ 729	$ 1,477	$ 2,238	$ 3,165	[1]	$ 3,052	[1]	$ 2,885	[1]
Purchased Services and Other	721	714	700	691	697	1,388	2,088	2,852	[1]	2,802	[1]	2,728	[1]
Depreciation and Amortization		405	403	404	395	799	1,202	1,658	[1],[2]	1,607	[1],[2]	1,502	[1],[2]
Total Expense	2,344	2,365	2,301	2,233	2,259	4,492	6,793	9,295	[1]	9,158	[1]	8,899	[1]
Operating Income	1,337	1,315	1,271	1,466	1,447	2,913	4,184	5,245	[1]	5,499	[1]	5,954	[1]
Earnings Before Income Taxes	1,168	1,144	1,102	1,296	1,287	2,583	3,685	4,555	[1]	4,829	[1]	5,345	[1]
Income Tax Expense	(288)	(262)	(274)	(312)	(313)	(625)	(899)	(1,085)	[1]	(1,161)	[1]	(1,231)	[1]
Net Earnings	$ 880	$ 882	$ 828	$ 984	$ 974	$ 1,958	$ 2,786	$ 3,470	[1],[3]	$ 3,668	[1],[3]	$ 4,114	[1],[4]
Net Earnings Per Share, Basic (in dollars per share)	$ 0.45	$ 0.45	$ 0.42	$ 0.49	$ 0.47	$ 0.96	$ 1.38	$ 1.79	[1]	$ 1.83	[1]	$ 1.93	[1]
Net Earnings Per Share, Assuming Dilution (in dollars per share)	$ 0.45	$ 0.45	$ 0.41	$ 0.49	$ 0.47	$ 0.96	$ 1.37	$ 1.79	[1]	$ 1.82	[1]	$ 1.92	[1]
Total Comprehensive Earnings (Note 10)	$ 886	$ 997	$ 846	$ 980	$ 976	$ 1,956	$ 2,802	$ 3,517	[3]	$ 3,799	[4]	$ 4,080	[3]
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Labor and Fringe	798	808	752	741	723	1,464	2,216			3,024		2,861
Purchased Services and Other	711	703	689	684	688	1,372	2,061			2,764		2,685
Depreciation and Amortization		417	399	402	393	795	1,194			1,611		1,500
Total Expense	2,327	2,360	2,277	2,217	2,242	4,459	6,736			9,096		8,830
Operating Income	1,354	1,320	1,295	1,482	1,464	2,946	4,241			5,561		6,023
Earnings Before Income Taxes	1,185	1,149	1,126	1,312	1,304	2,616	3,742			4,891		5,414
Income Tax Expense	(292)	(263)	(280)	(316)	(317)	(633)	(913)			(1,176)		(1,248)
Net Earnings	$ 893	$ 886	$ 846	$ 996	$ 987	$ 1,983	$ 2,829			$ 3,715		$ 4,166
Net Earnings Per Share, Basic (in dollars per share)	$ 0.46	$ 0.45	$ 0.42	$ 0.49	$ 0.48	$ 0.97	$ 1.40			$ 1.85		$ 1.95
Net Earnings Per Share, Assuming Dilution (in dollars per share)	$ 0.46	$ 0.45	$ 0.42	$ 0.49	$ 0.48	$ 0.97	$ 1.40			$ 1.85		$ 1.95
Total Comprehensive Earnings (Note 10)	$ 899	$ 946	$ 864	$ 992	$ 989	$ 1,981	$ 2,845			$ 3,791		$ 4,186
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Labor and Fringe	7	6	9	7	6	13	22			28		24
Purchased Services and Other	10	11	11	7	9	16	27			38		43
Depreciation and Amortization		(12)	4	2	2	4	8			(4)		2
Total Expense	17	5	24	16	17	33	57			62		69
Operating Income	(17)	(5)	(24)	(16)	(17)	(33)	(57)			(62)		(69)
Earnings Before Income Taxes	(17)	(5)	(24)	(16)	(17)	(33)	(57)			(62)		(69)
Income Tax Expense	4	1	6	4	4	8	14			15		17
Net Earnings	$ (13)	$ (4)	$ (18)	$ (12)	$ (13)	$ (25)	$ (43)			$ (47)		$ (52)
Net Earnings Per Share, Basic (in dollars per share)	$ (0.01)	$ 0	$ 0	$ 0	$ (0.01)	$ (0.01)	$ (0.02)			$ (0.02)		$ (0.02)
Net Earnings Per Share, Assuming Dilution (in dollars per share)	$ (0.01)	$ 0	$ (0.01)	$ 0	$ (0.01)	$ (0.01)	$ (0.03)			$ (0.03)		$ (0.03)
Total Comprehensive Earnings (Note 10)	$ (13)	$ 51	$ (18)	$ (12)	$ (13)	$ (25)	$ (43)			$ 8		$ (106)

[1] See Note 20, Revision of Prior Period Financial Statements

[2] See Note 20, Revision of Prior Period Financial Statements.

[3] See Note 20, Revision of Prior Period Financial Statements.

[4] See Note 20, Revision of Prior Period Financial Statements.