Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Cash and cash equivalents
Securities purchased under resale agreements	$ 92	$ 87
Restricted cash	606	514
Premises and equipment, accumulated depreciation	7,540	6,562
Other assets, reserves for credit losses	85	27
Liabilities
Long-term debt	$ 42,952	$ 57,835
Shareholders' Equity
Preferred shares, par value (in dollars per share)	$ 1.667	$ 1.667
Preferred shares, authorized (in shares)	20,000,000	20,000,000
Preferred shares, outstanding (in shares)	1,600	1,600
Preferred shares, issued (in shares)	1,600	1,600
Common shares, par value (in dollars per share)	$ 0.20	$ 0.20
Common shares, authorized (in shares)	3,600,000,000	3,600,000,000
Common shares, issued (in shares)	805,000,000	810,000,000
Common shares, outstanding (in shares)	805,000,000	810,000,000
Accumulated other comprehensive loss
Net unrealized debt securities gains (losses), tax	$ 20	$ 11
Foreign currency translation adjustments, tax	(381)	(319)
Net unrealized pension and other postretirement benefits, tax	(236)	(208)
Card Member Receivables [Member]
Cash and cash equivalents
Financing receivables, gross	43,701	57,413
Financing receivables, reserves for credit losses	267	619
Card Member Loans [Member]
Cash and cash equivalents
Financing receivables, gross	73,373	87,381
Financing receivables, reserves for credit losses	5,344	2,383
Other Loans [Member]
Cash and cash equivalents
Financing receivables, reserves for credit losses	238	152
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents
Restricted cash	47	85
Liabilities
Long-term debt	12,760	19,668
Variable Interest Entity, Primary Beneficiary [Member] | Card Member Receivables [Member]
Cash and cash equivalents
Financing receivables, gross	4,296	8,284
Variable Interest Entity, Primary Beneficiary [Member] | Card Member Loans [Member]
Cash and cash equivalents
Financing receivables, gross	$ 25,908	$ 32,230