SCHEDULE I - PARENT COMPANY FINANCIAL INFORMATION (Condensed Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 4,673	$ 4,054
Investment securities	12,554	10,972
Other current assets	5,276	3,806
Total current assets	23,641	19,888
Property and equipment, net	2,371	1,955
Equity method investments	1,170	1,063
Long-term investment securities	1,212	406
Other long-term assets	2,128	1,834
Total assets	34,969	29,074
Current liabilities:
Book overdraft	320	225
Short-term debt	600	699
Total current liabilities	13,394	10,929
Long-term debt	6,060	4,967
Other long-term liabilities	1,787	1,141
Total liabilities	21,241	17,037
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $1 par; 10,000,000 shares authorized; none issued	0	0
Common stock, $0.16 2/3 par; 300,000,000 shares authorized; 198,648,742 shares issued at December 31, 2020 and 198,629,992 shares issued at December 31, 2019	33	33
Capital in excess of par value	2,705	2,820
Retained earnings	20,517	17,483
Accumulated other comprehensive income (loss)	391	156
Treasury stock, at cost, 69,787,614 shares at December 31, 2020 and 66,524,771 shares at December 31, 2019	(9,918)	(8,455)
Total stockholders’ equity	13,728	12,037	$ 10,161	$ 9,842
Total liabilities and stockholders’ equity	34,969	29,074
Parent Company
Current assets:
Cash and cash equivalents	436	1,006
Investment securities	336	355
Receivable from operating subsidiaries	1,187	1,248
Other current assets	763	778
Total current assets	2,722	3,387
Property and equipment, net	1,774	1,403
Investments in subsidiaries	17,005	14,763
Equity method investments	1,147	1,063
Long-term investment securities	836	32
Other long-term assets	686	746
Total assets	24,170	21,394
Current liabilities:
Payable to operating subsidiaries	1,342	1,975
Current portion of notes payable to operating subsidiaries	36	36
Book overdraft	120	40
Short-term debt	600	699
Other current liabilities	1,438	1,128
Total current liabilities	3,536	3,878
Long-term debt	6,060	4,967
Other long-term liabilities	846	512
Total liabilities	10,442	9,357
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $1 par; 10,000,000 shares authorized; none issued	0	0
Common stock, $0.16 2/3 par; 300,000,000 shares authorized; 198,648,742 shares issued at December 31, 2020 and 198,629,992 shares issued at December 31, 2019	33	33
Capital in excess of par value	2,705	2,820
Retained earnings	20,517	17,483
Accumulated other comprehensive income (loss)	391	156
Treasury stock, at cost, 69,787,614 shares at December 31, 2020 and 66,524,771 shares at December 31, 2019	(9,918)	(8,455)
Total stockholders’ equity	13,728	12,037
Total liabilities and stockholders’ equity	$ 24,170	$ 21,394