Goodwill and other intangible assets (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization charges associated with finite-lived intangible assets	$ 371	$ 345	$ 740	$ 686
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total estimated amortization of finite-lived intangible assets for the six months ending December 31, 2016	700		700
Total estimated amortization of finite-lived intangible assets for 2017	1,300		1,300
Total estimated amortization of finite-lived intangible assets for 2018	1,200		1,200
Total estimated amortization of finite-lived intangible assets for 2019	1,100		1,100
Total estimated amortization of finite-lived intangible assets for 2020	1,000		1,000
Total estimated amortization of finite-lived intangible assets for 2021	$ 900		$ 900