Reportable Operating Segements and Geographic Operations (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense	$ 8,839	$ 8,436	$ 8,307	$ 7,889	$ 8,022	$ 7,774	$ 8,235	$ 8,088	$ 33,471	$ 32,119	$ 32,818
Pretax income	$ 1,821	$ 1,827	$ 1,949	$ 1,817	$ 1,161	$ 1,735	$ 3,016	$ 2,184	7,414	8,096	7,938
United States Geographic Region [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									24,737	24,133	24,927
Pretax income									7,071	8,202	7,500
EMEA Geographic Region [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									3,583	3,248	3,293
Pretax income									898	482	544
JAPA Geographic Region [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									3,204	3,052	2,791
Pretax income									602	559	587
LACC Geographic Region [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									2,396	2,274	2,412
Pretax income									610	597	693
Other Unallocated [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									(449)	(588)	(605)
Pretax income									$ (1,767)	$ (1,744)	$ (1,386)