Goodwill and intangible assets (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization charges associated with finite-lived intangible assets	$ 642,000,000	$ 397,000,000	$ 380,000,000
Total estimated amortization of finite- lived intangible assets for 2014	1,200,000,000
Total estimated amortization of finite- lived intangible assets for 2015	1,200,000,000
Total estimated amortization of finite- lived intangible assets for 2016	1,200,000,000
Total estimated amortization of finite-lived intangible assets for 2017	1,100,000,000
Total estimated amortization of finite-lived intangible assets for 2018	$ 902,000,000