Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt (Carrying Value Of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	May 12, 2015	Oct. 09, 2012
Debt Instrument [Line Items]
Long-term debt	$ 19,385	$ 18,066
Current portion of long-term debt	(1,598)	(849)
Long-term debt, less current portion	17,787	17,217
Senior Unsecured Notes [Member] \| 2.250%, due 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	0	$ 849
Interest rate on long-term debt		2.25%
Senior Unsecured Notes [Member] \| 2.500% due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 899	$ 897
Interest rate on long-term debt	2.50%	2.50%
Senior Unsecured Notes [Member] \| 4.350%, due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 699	$ 688
Interest rate on long-term debt	4.35%	4.35%
Senior Unsecured Notes [Member] \| 3.700%, due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 699	$ 698
Interest rate on long-term debt	3.70%	3.70%
Senior Unsecured Notes [Member] \| 2.950% due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 747	$ 747
Interest rate on long-term debt	2.95%	2.95%
Senior Unsecured Notes [Member] \| 3.125%, due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 847	$ 846
Interest rate on long-term debt	3.125%	3.125%
Senior Unsecured Notes [Member] \| 3.300%, due 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,013	$ 1,000
Interest rate on long-term debt	3.30%	3.30%
Senior Unsecured Notes [Member] \| 3.350% due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 846	$ 846
Interest rate on long-term debt	3.35%	3.35%
Senior Unsecured Notes [Member] \| 3.500%, due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 795	$ 794
Interest rate on long-term debt	3.50%	3.50%
Senior Unsecured Notes [Member] \| 2.375%, due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 845	$ 0
Interest rate on long-term debt	2.375%
Senior Unsecured Notes [Member] \| 3.650% due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,590	$ 1,589
Interest rate on long-term debt	3.65%	3.65%
Senior Unsecured Notes [Member] \| 4.101%, due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,253	$ 1,250
Interest rate on long-term debt	4.101%	4.101%
Senior Unsecured Notes [Member] \| 2.875%, due 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 819	$ 0
Interest rate on long-term debt	2.875%
Senior Unsecured Notes [Member] \| 5.950%, due 2034 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 334	$ 334
Interest rate on long-term debt	5.95%	5.95%
Senior Unsecured Notes [Member] \| 5.850%, due 2036 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 396	$ 396
Interest rate on long-term debt	5.85%	5.85%
Senior Unsecured Notes [Member] \| 6.375%, due 2037 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 366	$ 366
Interest rate on long-term debt	6.375%	6.375%
Senior Unsecured Notes [Member] \| 5.800%, due 2040 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 124	$ 124
Interest rate on long-term debt	5.80%	5.80%
Senior Unsecured Notes [Member] \| 4.625%, due 2042 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 888	$ 887
Interest rate on long-term debt	4.625%	4.625%
Senior Unsecured Notes [Member] \| 4.650%, due 2043 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 987	$ 986
Interest rate on long-term debt	4.65%	4.65%
Senior Unsecured Notes [Member] \| 4.650%, due 2044 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 792	$ 791
Interest rate on long-term debt	4.65%	4.65%
Senior Unsecured Notes [Member] \| 5.100%, due 2044 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 594	$ 594
Interest rate on long-term debt	5.10%	5.10%
Senior Unsecured Notes [Member] \| 4.375% due 2047 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,386	$ 1,386
Interest rate on long-term debt	4.375%	4.375%
Senior Unsecured Notes [Member] \| 4.550%, due 2048 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 838	$ 838
Interest rate on long-term debt	4.55%	4.55%
Senior Unsecured Notes [Member] \| 3.700%, due 2049 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 811	$ 0
Interest rate on long-term debt	3.70%
Senior Unsecured Notes [Member] \| 4.850%, due 2054 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 247	$ 247
Interest rate on long-term debt	4.85%	4.85%
Remarketable Subordinated Notes [Member] \| 1.900%, due 2028 [Member]
Debt Instrument [Line Items]
Interest rate on long-term debt			1.90%
Senior Convertible Debentures [Member] \| 2.750%, due 2042 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 145	$ 191
Interest rate on long-term debt	2.75%	2.75%		2.75%
Surplus Notes [Member] \| 9.000%, due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 25	$ 25
Interest rate on long-term debt	9.00%	9.00%
Commercial Paper [Member]
Debt Instrument [Line Items]
Commercial paper	$ 400	$ 697