Income Taxes Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amount
Income before income taxes	$ 4,958	$ 5,079	$ 4,500
Federal statutory tax	1,735	1,778	1,575
State tax effect, net of federal benefit	27	29	19
Foreign tax effect	(144)	(108)	(208)
Foreign repatriation	(172)	(177)	(14)
Impact of settlements with tax authorities	(147)	0	0
Other foreign tax credits	(109)	(6)	(3)
Other, net	(40)	(54)	15
Income tax expense	$ 1,150	$ 1,462	$ 1,384
Percent
Federal statutory tax	35.00%	35.00%	35.00%
State tax effect, net of federal benefit	0.50%	0.60%	0.40%
Foreign tax effect	(2.90%)	(2.10%)	(4.60%)
Foreign repatriation	(3.50%)	(3.50%)	(0.30%)
Impact of settlements with tax authorities	(2.90%)	0.00%	0.00%
Other foreign tax credits	(2.20%)	(0.10%)	(0.00%)
Other, net	(0.80%)	(1.10%)	0.30%
Income tax expense	23.20%	28.80%	30.80%