Goodwill and other intangible assets (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization charges associated with finite-lived intangible assets	$ 320	$ 373
Total estimated amortization of finite-lived intangible assets for the nine months ending December 31, 2018	1,000
Total estimated amortization of finite-lived intangible assets for 2019	1,300
Total estimated amortization of finite-lived intangible assets for 2020	1,200
Total estimated amortization of finite-lived intangible assets for 2021	1,000
Total estimated amortization of finite-lived intangible assets for 2022	900
Total estimated amortization of finite-lived intangible assets for 2023	$ 900