Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 2,177	$ 2,143	$ 1,980
Other comprehensive income (loss), net of related taxes:
Foreign currency translation, net of related taxes of $21, ($11) and ($101), respectively	900	(372)	(735)
Net unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment and net of related taxes of $272, ($119), and ($195), respectively	367	(181)	(331)
Net unrealized gains (losses) on available-for-sale securities designated in fair value hedges, net of related taxes of $16, $16 and $5, respectively	22	23	12
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit, net of related taxes of $3, $5 and $8, respectively	3	7	13
Net unrealized gains (losses) on cash flow hedges, net of related taxes of ($181), ($42) and $24, respectively	(285)	(64)	17
Net unrealized gains (losses) on retirement plans, net of related taxes of $8, $1 and $51, respectively	24	(11)	89
Other comprehensive income (loss)	1,031	(598)	(935)
Total comprehensive income	$ 3,208	$ 1,545	$ 1,045