Stockholders' equity (Accumulated Other Comprehensive Income (Loss), Textual) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Income tax expense or (benefit) for reclassification adjustments to income for available-for-sale securities	$ (14)	$ 3	$ (8)
Income taxes expense or (benefit) for unrealized gains and losses for available-for-sale securities	22	(9)	9
Income taxes expense or (benefit) for unrealized gains and losses for cash flow hedges	28	21	68
Income tax expense or (benefit) reclassification adjustments to income for cash flow hedges	$ (46)	$ 55	$ (226)