Segment And Geographic Information (Geographic Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 16,329	$ 16,726	$ 16,297	$ 15,304	$ 15,947	$ 15,800	$ 17,068	$ 15,526	$ 64,656	$ 64,341	$ 60,828
Long-Lived Assets	10,106				9,953				10,106	9,953
UNITED STATES
Segment Reporting Information [Line Items]
Revenues									27,509	28,726	27,894
Long-Lived Assets	6,488				6,615				6,488	6,615
Switzerland [Member]
Segment Reporting Information [Line Items]
Revenues									13,016	12,911	14,095
CAYMAN ISLANDS
Segment Reporting Information [Line Items]
Revenues									4,374	5,724	4,189
GERMANY
Segment Reporting Information [Line Items]
Revenues									2,026	2,179	2,090
BRAZIL
Segment Reporting Information [Line Items]
Revenues									2,381	1,702	1,589
Long-Lived Assets	869				802				869	802
Other Foreign [Member]
Segment Reporting Information [Line Items]
Revenues									15,350	13,099	$ 10,971
Long-Lived Assets	$ 2,749				$ 2,536				$ 2,749	$ 2,536