Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle
Income tax provision	$ 572	$ 746
Statement of Cash Flows
Cash paid to other suppliers and employees	(3,823)	(2,934)
Net cash provided by operating activities	3,533	2,439
Net cash used in financing activities	(4,133)	(2,487)
Reconciliation of net income to net cash provided by operating activities:
Accrued expenses	1,848	768
Income Statement
Operating expenses	4,787	4,559
Operating profit	1,793	2,185
Other expense	7	9
Previously Reported
Statement of Cash Flows
Cash paid to other suppliers and employees		(2,961)
Net cash provided by operating activities		2,412
Excess tax benefits from stock-based compensation		27
Net cash used in financing activities		(2,460)
Reconciliation of net income to net cash provided by operating activities:
Accrued expenses		741
Income Statement
Operating expenses		4,568
Operating profit		2,176
Adjustment
Statement of Cash Flows
Cash paid to other suppliers and employees		27
Net cash provided by operating activities		27
Excess tax benefits from stock-based compensation		(27)
Net cash used in financing activities		(27)
Reconciliation of net income to net cash provided by operating activities:
Accrued expenses		27
Income Statement
Operating expenses		(9)
Operating profit		9
Other expense		$ 9
ASU 2016-09 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle
Income tax provision	$ (19)