Income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income taxes paid	$ 522	$ 1,143	$ 1,595
Components of profit (loss) before taxes
U.S	(2,053)	636	276
Non-U.S	2,192	2,803	2,876
Consolidated profit before taxes	139	3,439	3,152
Current tax provision (benefit):
U.S.	(90)	525	715
Non-U.S.	718	656	883
State (U.S.)	(5)	42	48
Current tax provision (benefit)	623	1,223	1,646
Deferred tax provision (benefit):
U.S.	(544)	(367)	(763)
Non-U.S.	(108)	66	(116)
State (U.S.)	221	(6)	(75)
Deferred tax provision (benefit)	(431)	(307)	(954)
Provision (benefit) for income taxes	$ 192	$ 916	$ 692