- Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Salaries and employee benefits	$ 2,687	$ 2,616	$ 2,495
Other	$ 422	$ 409	$ 389