Income taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Discrete tax benefits related to reinstatement of the U.S. R&D tax credit			$ 79,000,000
Changes in valuation allowance balances	$ 9,000,000	$ 24,000,000	2,000,000
Tax loss carryforward, U.S. and non-U.S.	35,000,000
Tax loss carryforward, U.S. and non-U.S., set to expire	0
Amount of undistributed foreign earnings	8,350,000,000
Cash payments for income taxes	1,167,000,000	1,104,000,000	569,000,000
Amount of deferred tax assets possibly to be realized	12,000,000	56,000,000
Unrecognized Tax Benefits	84,000,000	108,000,000	91,000,000	$ 184,000,000
Maximum
Income Tax Contingency [Line Items]
Deferred tax liability increase due to tax depreciation related position	150,000,000
Foreign Tax Authority
Income Tax Contingency [Line Items]
Benefits from tax holidays	$ 60,000,000	$ 44,000,000	$ 40,000,000
Tax holiday, review time period	5 years