Correction of Prior Period Amounts (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Other assets	$ 10,200	$ 9,620
Other liabilities	2,837	2,048
Retained earnings	8,788	9,524
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	16,367	16,580	$ 18,355	$ 17,386
Noncontrolling interests	87	72
Noncontrolling Interests
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	87	72	100	153
Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 8,788	$ 9,524	$ 10,936	$ 10,101