Incentive Program (Narrative) (Details) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Minimum ownership of affiliates needed for awards	50.00%
Options and stock appreciation rights grant, minimum percentage of market value, date of grant	100.00%
Share-based compensation arrangement by share-based payment award expiration period	10 years
Number of shares issuable under 2003 incentive program, maximum	220,000
Remaining shares available for award under 2003 incentive program	82,000
Restricted Stock [Member]
Long-term incentive awards	8,771	8,916	9,583
Percent of the shares in each award vesting after three years	50.00%
Percent of shares in each award vesting after five years	50.00%
Percent of the shares in each award vesting after seven years	50.00%
Percent of shares in each award vesting in later of ten years or retirement	50.00%
Unrecognized compensation cost	$ 1,899
Unrecognized compensation cost, weighted-average period of recognition, years	4 years 5 months
Compensation cost charged against income	$ 774	$ 856	$ 880
Income tax benefit recognized in income	42	78	80
Fair value of shares/awards vested	722	826	851
Cash payments, vested restricted stock units	$ 61	$ 64	$ 67
Restricted Stock [Member] | Minimum [Member]
Vesting Period	3 years
Restricted Stock [Member] | Minimum [Member] | Executive Officer [Member]
Vesting Period	5 years
Restricted Stock [Member] | Maximum [Member]
Vesting Period	7 years
Restricted Stock [Member] | Maximum [Member] | Executive Officer [Member]
Vesting Period	10 years