Commitments, Contingencies and Guarantees (Credit Risk Of Off-Balance Sheet Financial Instruments By Contractual Amounts) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Unused commitments to extend credit	$ 60,626		$ 56,644
Standby Letters Of Credit Commitment	1,773		1,742
Commercial letters of credit	42		132
Liabilities associated with standby letters of credit	31		25
Assets associated with standby letters of credit	31		25
Reserve for unfunded credit commitments	$ 87	$ 92	$ 126	$ 149	$ 105	$ 45