Income taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Interest and penalties related to unrecognized tax benefits recognized in income tax provision	$ 125,000,000	$ 17,000,000	$ 35,000,000
Accrued interest and penalties associated with unrecognized tax benefits	276,000,000	151,000,000
Tax Credit Carryforward [Line Items]
Significant change in UTB is reasonably possible, amount of unrecorded benefit	63,000,000
Undistributed earnings of our foreign operations that are intended to be invested indefinitely outside of the United States	36,600,000,000
Additional income taxes required to be accrued and paid if earnings of foreign operations that are intended to be indefinitely invested outside of the United States were repatriated	12,800,000,000
Excise Tax Rate [Abstract]
Income taxes paid	$ 1,100,000,000	$ 919,000,000	$ 269,000,000
Puerto Rico [Member]
Excise Tax Rate [Abstract]
Effective excise tax rate for first half of 2013	4.00%
Domestic
Tax Credit Carryforward [Line Items]
Tax credit carryforwards available to reduce income taxes	$ 20,000,000
Tax credit carryforwards, valuation allowance	0
NOL carryforwards available to reduce income taxes	147,000,000
Domestic | Valuation allowance, operating loss carryforwards [Member]
Tax Credit Carryforward [Line Items]
NOL carryforwards available to reduce income taxes	6,000,000
State [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards available to reduce income taxes	385,000,000
Tax credit carryforwards, valuation allowance	363,000,000
NOL carryforwards available to reduce income taxes	469,000,000
State [Member] | Valuation allowance, operating loss carryforwards [Member]
Tax Credit Carryforward [Line Items]
NOL carryforwards available to reduce income taxes	445,000,000
Foreign
Tax Credit Carryforward [Line Items]
NOL carryforwards available to reduce income taxes	1,800,000,000
NOLs with no valuation allowance and no expiration	594,000,000
Foreign | Valuation allowance, operating loss carryforwards [Member]
Tax Credit Carryforward [Line Items]
NOL carryforwards available to reduce income taxes	587,000,000
Expiration in tax years 2022-2030 [Member] | State [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards, valuation allowance	$ 0