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
	Jun. 30, 2024		Mar. 31, 2024		Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023		Mar. 31, 2023		Jun. 30, 2024	[1]	Jun. 30, 2023		Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Labor and Fringe	$ 766		$ 805		$ 814	$ 761	$ 748	[1]	$ 729		$ 1,571		$ 1,477	[1]	$ 2,238	$ 3,052	$ 2,885
Purchased Services and Other	699		721		714	700	691	[1]	697		1,420		1,388	[1]	2,088	2,802	2,728
Depreciation and Amortization	410				405	403	404	[1]	395		820		799	[2]	1,202	1,607	1,502
Total Expense	2,253		2,344		2,365	2,301	2,233	[1]	2,259		4,597		4,492	[1]	6,793	9,158	8,899
Operating Income	1,448		1,337		1,315	1,271	1,466	[1]	1,447		2,785		2,913	[1]	4,184	5,499	5,954
Earnings Before Income Taxes	1,267		1,168		1,144	1,102	1,296	[1]	1,287		2,435		2,583	[1]	3,685	4,829	5,345
Income Tax Expense	(304)		(288)		(262)	(274)	(312)	[1]	(313)		(592)		(625)	[1]	(899)	(1,161)	(1,231)
Net Earnings	$ 963	[3]	$ 880	[3]	$ 882	$ 828	$ 984	[1]	$ 974	[4]	$ 1,843		$ 1,958	[1]	$ 2,786	$ 3,668	$ 4,114
Net Earnings Per Share, Basic (in dollars per share)	$ 0.50		$ 0.45		$ 0.45	$ 0.42	$ 0.49	[1]	$ 0.47		$ 0.94		$ 0.96	[1]	$ 1.38	$ 1.83	$ 1.93
Net Earnings Per Share, Assuming Dilution (in dollars per share)	$ 0.49		$ 0.45		$ 0.45	$ 0.41	$ 0.49	[1]	$ 0.47		$ 0.94		$ 0.96	[1]	$ 1.37	$ 1.82	$ 1.92
Total Comprehensive Earnings (Note 10)	$ 966	[3]	$ 886	[3]	$ 997	$ 846	$ 980	[1]	$ 976	[4]	$ 1,852		$ 1,956	[1]	$ 2,802	$ 3,799	$ 4,080
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 11, Revision of Prior Period Financial Statements.

[2] See Note 11, Revision of Prior Period Financial Statements.

[3] See Note 11, Revision of Prior Period Financial Statements.

[4] See Note 11, Revision of Prior Period Financial Statements.