Discover Financial Services (DFS) 10-Q 28 Oct 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Oct. 22, 2021
Cover [Abstract]
Document type	10-Q
Document quarterly report	true
Document period end date	Sep. 30, 2021
Document transition report	false
Entity file number	001-33378
Entity registrant name	DISCOVER FINANCIAL SERVICES
Entity incorporation, state	DE
Entity tax identification number	36-2517428
Entity address, address line one	2500 Lake Cook Road
Entity address, city or town	Riverwoods
Entity address, state or province	IL
Entity address, postal zip code	60015
Entity phone number, city area code	224
Entity phone number, local phone number	405-0900
Title of 12(b) security	Common Stock, par value $0.01 per share
Trading symbol	DFS
Security exchange name	NYSE
Entity current reporting status	Yes
Entity interactive data current	Yes
Entity filer category	Large Accelerated Filer
Smaller reporting company	false
Emerging growth company	false
Entity shell company	false
Entity common stock, shares outstanding		293,075,754
Entity central index key	0001393612
Current fiscal year end date	--12-31
Document fiscal year focus	2021
Document fiscal period focus	Q3
Amendment flag	false

Condensed Consolidated Statemen

Condensed Consolidated Statements of Financial Condition - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents	$ 12,716	$ 13,564
Restricted cash	32	25
Other short-term investments	0	2,200
Investment securities (includes available-for-sale securities of $7,791 and $9,654 reported at fair value with associated amortized cost of $7,566 and $9,277 at September 30, 2021 and December 31, 2020, respectively)	8,014	9,914
Loan receivables
Loan receivables	89,542	90,449
Allowance for credit losses	(6,861)	(8,226)
Net loan receivables	82,681	82,223
Premises and equipment, net	987	1,027
Goodwill	255	255
Intangible assets, net	1	95
Other assets	3,858	3,586
Total assets	108,544	112,889
Deposits
Interest-bearing deposit accounts	71,126	75,695
Non-interest bearing deposit accounts	1,436	1,209
Total deposits	72,562	76,904
Long-term borrowings	18,516	21,241
Accrued expenses and other liabilities	4,203	3,860
Total liabilities	95,281	102,005
Commitments, contingencies and guarantees (Notes 10, 13 and 14)
Stockholders' Equity
Common stock, par value $0.01 per share; 2,000,000,000 shares authorized; 568,761,125 and 567,898,063 shares issued at September 30, 2021 and December 31, 2020, respectively	6	6
Preferred stock, par value $0.01 per share; 200,000,000 shares authorized; 10,700 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	1,056	1,056
Additional paid-in capital	4,345	4,257
Retained earnings	23,846	19,955
Accumulated other comprehensive (loss) income	(68)	45
Treasury stock, at cost; 274,001,084 and 261,300,765 shares at September 30, 2021 and December 31, 2020, respectively	(15,922)	(14,435)
Total stockholders' equity	13,263	10,884
Total liabilities and stockholders' equity	108,544	112,889
Variable Interest Entity, Primary Beneficiary [Member]
Assets
Restricted cash	32	25
Loan receivables
Loan receivables	24,751	27,546
Allowance for credit losses	(1,436)	(1,936)
Other assets	4	4
Deposits
Long-term borrowings	9,064	10,840
Accrued expenses and other liabilities	$ 5	$ 8

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Available-for-sale investment securities, fair value	[1]	$ 7,791	$ 9,654
Available-for-sale investment securities, amortized cost	[1]	$ 7,566	$ 9,277
Common Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01
Common Stock, Shares Authorized		2,000,000,000	2,000,000,000
Common Stock, Shares, Issued		568,761,125	567,898,063
Preferred stock, par or stated value per Share		$ 0.01	$ 0.01
Preferred Stock, Shares Authorized		200,000,000	200,000,000
Preferred Stock, Shares Issued		10,700	10,700
Preferred Stock, Shares Outstanding		10,700	10,700
Treasury Stock, Shares		274,001,084	261,300,765
[1]	Available-for-sale investment securities are reported at fair value.

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest income
Credit card loans	$ 2,193	$ 2,171	$ 6,452	$ 6,760
Other loans	433	446	1,301	1,369
Investment securities	45	58	142	171
Other interest income	3	6	14	35
Total interest income	2,674	2,681	7,909	8,335
Interest expense
Deposits	156	287	519	1,000
Short-term borrowings	0	3	0	3
Long-term borrowings	113	126	356	479
Total interest expense	269	416	875	1,482
Net interest income	2,405	2,265	7,034	6,853
Provision for credit losses	185	750	(45)	4,603
Net interest income after provision for credit losses	2,220	1,515	7,079	2,250
Other income
Discount and interchange revenue, net	299	238	879	691
Protection products revenue	43	44	129	135
Loan fee income	121	100	333	304
Transaction processing revenue	58	50	167	143
Unrealized (losses) gains on equity investments	(167)	0	562	0
Realized gains on equity investments	0	0	0	79
Other income	18	17	47	59
Total other income	372	449	2,117	1,411
Other expense
Employee compensation and benefits	483	471	1,487	1,390
Marketing and business development	210	140	539	500
Information processing and communications	121	111	375	342
Professional fees	198	151	567	525
Premises and equipment	23	26	69	83
Other expense	155	106	456	401
Total other expense	1,190	1,005	3,493	3,241
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	1,402	959	5,703	420
Income tax expense	311	188	1,321	78
Net income	1,091	771	4,382	342
Net Income (Loss) Available to Common Stockholders, Diluted	1,055	751	4,289	309
Net income allocated to common stockholders	$ 1,055	$ 751	$ 4,289	$ 309
Basic earnings per common share	$ 3.54	$ 2.45	$ 14.17	$ 1
Diluted earnings per common share	$ 3.54	$ 2.45	$ 14.16	$ 1

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 1,091	$ 771	$ 4,382	$ 342
Other comprehensive (loss) income, net of tax
Unrealized (losses) gains on available-for-sale investment securities, net of tax	(29)	(32)	(115)	208
Unrealized gains on cash flow hedges, net of tax	0	3	2	4
Other comprehensive (loss) income	(29)	(29)	(113)	212
Comprehensive income	$ 1,062	$ 742	$ 4,269	$ 554

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock [Member]	Series C Preferred Stock [Member]	Series C Preferred Stock [Member]Retained Earnings [Member]	Series D Preferred Stock	Series D Preferred StockRetained Earnings [Member]
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2019			6,000
Common stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2019				566,654,000
Stockholders' equity, balance at beginning of period at Dec. 31, 2019	$ 11,859		$ 563	$ 6	$ 4,206	$ 21,290		$ (119)	$ (14,087)
Stockholders' equity, balance at beginning of period (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019		$ (1,902)					$ (1,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	342					342
Other comprehensive loss	212							212
Purchases of treasury stock	(343)								(343)
Common stock issued under employee benefit plans (in shares)				163,000
Common stock issued under employee benefit plans	7			$ 0	7
Common stock issued and stock-based compensation expense (in shares)				927,000
Common stock issued and stock-based compensation expense	22			$ 0	22
Stock Issued During Period, Shares, New Issues			5,000
Stock Issued During Period, Value, New Issues	493		$ 493
Dividends — common stock	(407)					(407)
Dividends — preferred stock	(31)									$ (31)	$ (31)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2020			11,000
Common stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2020				567,744,000
Stockholders' equity, balance at end of period at Sep. 30, 2020	10,252		$ 1,056	$ 6	4,235	19,292		93	(14,430)
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Jun. 30, 2020			11,000
Common stock, shares outstanding, balance at beginning of period (in shares) at Jun. 30, 2020				567,653,000
Stockholders' equity, balance at beginning of period at Jun. 30, 2020	9,643		$ 1,056	$ 6	4,216	18,673		122	(14,430)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	771					771
Other comprehensive loss	(29)							(29)
Common stock issued under employee benefit plans (in shares)				50,000
Common stock issued under employee benefit plans	3			$ 0	3
Common stock issued and stock-based compensation expense (in shares)				41,000
Common stock issued and stock-based compensation expense	16			$ 0	16
Dividends — common stock	(137)					(137)
Dividends — preferred stock	(15)									(15)	(15)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2020			11,000
Common stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2020				567,744,000
Stockholders' equity, balance at end of period at Sep. 30, 2020	$ 10,252		$ 1,056	$ 6	4,235	19,292		93	(14,430)
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2020	10,700		11,000
Common stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2020				567,898,000
Stockholders' equity, balance at beginning of period at Dec. 31, 2020	$ 10,884		$ 1,056	$ 6	4,257	19,955		45	(14,435)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,382					4,382
Other comprehensive loss	(113)							(113)
Purchases of treasury stock	(1,487)								(1,487)
Common stock issued under employee benefit plans (in shares)				67,000
Common stock issued under employee benefit plans	7			$ 0	7
Common stock issued and stock-based compensation expense (in shares)				796,000
Common stock issued and stock-based compensation expense	81			$ 0	81
Dividends — common stock	(422)					(422)
Dividends — preferred stock	$ (69)									(31)	(31)	$ (38)	$ (38)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2021	10,700		11,000
Common stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2021				568,761,000
Stockholders' equity, balance at end of period at Sep. 30, 2021	$ 13,263		$ 1,056	$ 6	4,345	23,846		(68)	(15,922)
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Jun. 30, 2021			11,000
Common stock, shares outstanding, balance at beginning of period (in shares) at Jun. 30, 2021				568,693,000
Stockholders' equity, balance at beginning of period at Jun. 30, 2021	13,171		$ 1,056	$ 6	4,319	22,936		(39)	(15,107)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,091					1,091
Other comprehensive loss	(29)							(29)
Purchases of treasury stock	(815)								(815)
Common stock issued under employee benefit plans (in shares)				21,000
Common stock issued under employee benefit plans	2			$ 0	2
Common stock issued and stock-based compensation expense (in shares)				47,000
Common stock issued and stock-based compensation expense	24			$ 0	24
Dividends — common stock	(151)					(151)
Dividends — preferred stock	$ (30)									$ (15)	$ (15)	$ (15)	$ (15)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2021	10,700		11,000
Common stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2021				568,761,000
Stockholders' equity, balance at end of period at Sep. 30, 2021	$ 13,263		$ 1,056	$ 6	$ 4,345	$ 23,846		$ (68)	$ (15,922)

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Dividends declared, common stock (dollars per share)	$ 0.50	$ 0.44	$ 1.38	$ 1.32
Series C Preferred Stock [Member]
Dividends declared, preferred stock (dollars per share)	2,750	$ 2,750	5,500	$ 5,500
Series D Preferred Stock
Dividends declared, preferred stock (dollars per share)	$ 3,063		$ 7,674

Condensed Consolidated Statem_7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows provided by operating activities
Net income	$ 4,382	$ 342
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	(45)	4,603
Deferred income taxes	388	(600)
Depreciation and amortization	387	362
Amortization of deferred revenues	(217)	(245)
Net unrealized and realized gains on investments and other assets	(531)	(40)
Other, net	227	87
Changes in assets and liabilities:
(Increase) decrease in other assets	(273)	212
Increase (decrease) in accrued expenses and other liabilities	359	(158)
Net cash provided by operating activities	4,677	4,563
Cash flows provided by (used for) investing activities
Maturities of other short-term investments	2,200	0
Purchases of other short-term investments	0	(8,046)
Maturities of available-for-sale investment securities	1,709	724
Purchases of available-for-sale investment securities	(9)	0
Maturities of held-to-maturity investment securities	63	34
Purchases of held-to-maturity investment securities	(28)	(44)
Net principal (disbursed) repaid on loans originated for investment	(255)	5,316
Proceeds from the sale of available-for-sale securities	5	0
Proceeds from the sale of other investments	0	94
Purchases of other investments	(108)	(54)
Purchases of premises and equipment	(146)	(206)
Net cash provided by (used for) investing activities	3,431	(2,182)
Cash flows (used for) provided by financing activities
Proceeds from issuance of securitized debt	1,731	0
Maturities and repayment of securitized debt	(3,445)	(2,974)
Proceeds from issuance of other long-term borrowings	0	494
Maturities and repayment of other long-term borrowings	(922)	(1,754)
Proceeds from issuance of common stock	7	7
Purchases of treasury stock	(1,487)	(343)
Net (decrease) increase in deposits	(4,359)	5,245
Proceeds from issuance of preferred stock, net	0	493
Dividends paid on common and preferred stock	(474)	(424)
Net cash (used for) provided by financing activities	(8,949)	744
Net (decrease) increase in cash, cash equivalents and restricted cash	(841)	3,125
Cash, cash equivalents and restricted cash, at the beginning of the period	13,589	6,964
Cash, cash equivalents and restricted cash, at the end of the period	12,748	10,089
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	12,716	9,513
Restricted cash	$ 32	$ 576

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	Background and Basis of Presentation Description of Business Discover Financial Services ("DFS" or the "Company") is a digital banking and payment services company. The Company is a bank holding company under the Bank Holding Company Act of 1956 and a financial holding company under the Gramm-Leach-Bliley Act. Therefore, the Company is subject to oversight, regulation and examination by the Board of Governors of the Federal Reserve System (the "Federal Reserve"). The Company provides digital banking products and services and payment services through its subsidiaries. The Company offers credit card loans, private student loans, personal loans, home loans and deposit products to its customers. The Company also operates the Discover Network, the PULSE network ("PULSE") and Diners Club International ("Diners Club"), collectively known as the Discover Global Network. The Discover Network processes transactions for Discover-branded credit and debit cards and provides payment transaction processing and settlement services. PULSE operates an electronic funds transfer network, providing financial institutions issuing debit cards on the PULSE network with access to ATMs domestically and internationally and merchant acceptance throughout the United States for debit card transactions. Diners Club is a global payments network of licensees, which are generally financial institutions, that issue Diners Club branded credit and charge cards and/or provide card acceptance services. The Company manages its business activities in two segments, Digital Banking and Payment Services, based on the products and services provided. See Note 17: Segment Disclosures for a detailed description of each segment's operations and the allocation conventions used in business segment reporting. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP") for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, the financial statements reflect all adjustments necessary for the fair presentation of results for the interim period. All such adjustments are of a normal, recurring nature. The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and related disclosures. These estimates are based on information available as of the date of the condensed consolidated financial statements. The Company believes that the estimates used in the preparation of the condensed consolidated financial statements are reasonable. Actual results could differ from these estimates. These interim condensed consolidated financial statements should be read in conjunction with the Company's 2020 audited consolidated financial statements filed with the Company's annual report on Form 10-K for the year ended December 31, 2020.

Investments

Investments	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The Company's other short-term investments and investment securities consist of the following (dollars in millions): September 30, December 31, United States Treasury bills (1) $ — $ 2,200 Total other short-term investments $ — $ 2,200 United States Treasury (2) and U.S. GSE (3) securities $ 7,580 $ 9,354 Residential mortgage-backed securities - Agency (3) 434 560 Total investment securities $ 8,014 $ 9,914 (1) Includes United States Treasury bills with maturity dates greater than 90 days but less than one year at the time of acquisition. (2) Includes $56 million and $117 million of United States Treasury securities pledged as swap collateral as of September 30, 2021 and December 31, 2020, respectively. (3) Consists of securities issued by Fannie Mae, Freddie Mac, Ginnie Mae, or the Federal Home Loan Bank. The amortized cost, gross unrealized gains and losses and fair value of available-for-sale and held-to-maturity investment securities are as follows (dollars in millions): Amortized Gross Gross Fair Value At September 30, 2021 Available-for-Sale Investment Securities (1) United States Treasury and U.S. GSE securities $ 7,362 $ 218 $ — $ 7,580 Residential mortgage-backed securities - Agency 204 7 — 211 Total available-for-sale investment securities $ 7,566 $ 225 $ — $ 7,791 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 223 $ 5 $ (1) $ 227 Total held-to-maturity investment securities $ 223 $ 5 $ (1) $ 227 At December 31, 2020 Available-for-Sale Investment Securities (1) United States Treasury securities $ 8,987 $ 367 $ — $ 9,354 Residential mortgage-backed securities - Agency 290 10 — 300 Total available-for-sale investment securities $ 9,277 $ 377 $ — $ 9,654 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 260 $ 9 $ — $ 269 Total held-to-maturity investment securities $ 260 $ 9 $ — $ 269 (1) Available-for-sale investment securities are reported at fair value. (2) Held-to-maturity investment securities are reported at amortized cost. (3) Amounts represent residential mortgage-backed securities ("RMBS") that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives. The Company invests in United States Treasury obligations and securities issued by government agencies and government-sponsored enterprises of the United States of America ("U.S. GSEs"), which have long histories with no credit losses and are explicitly or implicitly guaranteed by the United States government. Therefore, management has concluded that there is no expectation of non-payment on its investment securities and does not record an allowance for credit losses on these investments. At September 30, 2021, there were three investment securities with an aggregate fair value of $118 million that had an immaterial aggregate gross unrealized loss for less than 12 months and no securities in an unrealized loss position for more than 12 months. As of December 31, 2020, there were no investment securities with aggregate gross unrealized losses. During the three and nine months ended September 30, 2021, the Company received $5 million of proceeds from the sale of available-for-sale securities. As a result of the sale, the Company recognized an immaterial gain during the three and nine months ended September 30, 2021. There were no proceeds from sales or recognized gains and losses on available-for-sale securities during the three and nine months ended September 30, 2020. See Note 9: Accumulated Other Comprehensive Income for unrealized gains and losses on available-for-sale securities during the three and nine months ended September 30, 2021 and 2020. Maturities of available-for-sale debt securities and held-to-maturity debt securities are provided in the following table (dollars in millions): At September 30, 2021 One Year After One After Five After Ten Total Available-for-Sale Investment Securities—Amortized Cost United States Treasury and U.S. GSE securities $ 2,616 $ 4,737 $ 9 $ — $ 7,362 Residential mortgage-backed securities - Agency (1) 2 21 174 7 204 Total available-for-sale investment securities $ 2,618 $ 4,758 $ 183 $ 7 $ 7,566 Held-to-Maturity Investment Securities—Amortized Cost Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 223 $ 223 Total held-to-maturity investment securities $ — $ — $ — $ 223 $ 223 Available-for-Sale Investment Securities—Fair Values United States Treasury and U.S. GSE securities $ 2,641 $ 4,931 $ 8 $ — $ 7,580 Residential mortgage-backed securities - Agency (1) 2 21 180 8 211 Total available-for-sale investment securities $ 2,643 $ 4,952 $ 188 $ 8 $ 7,791 Held-to-Maturity Investment Securities—Fair Values Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 227 $ 227 Total held-to-maturity investment securities $ — $ — $ — $ 227 $ 227 (1) Maturities of RMBS are reflective of the contractual maturities of the investment. Other Investments As a part of the Company's community reinvestment initiatives, the Company has made equity investments in certain limited partnerships and limited liability companies that finance the construction and rehabilitation of affordable rental housing and stimulate economic development in low- to moderate-income communities. These investments are accounted for using the equity method of accounting and are recorded within other assets. The related commitment for future investments is recorded in accrued expenses and other liabilities within the condensed consolidated statements of financial condition. The portion of each investment's operating results allocable to the Company reduces the carrying value of the investments and is recorded in other expense within the condensed consolidated statements of income. The Company further reduces the carrying value of the investments by recognizing any amounts that are in excess of future net tax benefits in other expense. The Company earns a return primarily through tax credits allocated to the affordable housing projects and the community revitalization projects. The Company does not consolidate these investments as the Company does not have a controlling financial interest in the investee entities. As of September 30, 2021 and December 31, 2020, the Company had outstanding investments in these entities of $366 million and $353 million, respectively, and related contingent liabilities for unconditional and legally binding delayed equity contributions of $64 million and $93 million, respectively. Of the above outstanding equity investments, the Company had $324 million of investments related to affordable housing projects as of September 30, 2021 and December 31, 2020, which had $52 million and $79 million of related contingent liabilities for unconditional and legally binding delayed equity contributions, respectively. The Company holds non-controlling equity positions in several payment services entities. Most of these investments are not subject to equity method accounting because the Company does not have significant influence over the investee. The common or preferred equity securities that the Company holds typically do not have readily determinable fair values. As a result, the majority of these investments are carried at cost minus impairment, if any. As of September 30, 2021 and December 31, 2020, the carrying value of these investments, which are recorded within other assets on the Company's condensed consolidated statements of financial condition, was $31 million and $35 million, respectively. The Company also holds non-controlling equity positions in payment service entities that have actively traded stock and therefore have readily determinable fair values. As a result, these investments are carried at fair value based on the quoted share prices. As of September 30, 2021 and December 31, 2020, the carrying value of these investments, which are recorded within other assets on the Company's condensed consolidated statements of financial condition, was $600 million and $8 million, respectively. During the three and nine months ended September 30, 2021, the Company recognized unrealized losses of approximately $167 million and unrealized gains of approximately $562 million, respectively, on the condensed consolidated statements of income related to these investments. The Company recognized no unrealized losses or gains during the three and nine months ended September 30, 2020.

Loan Receivables

Loan Receivables	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Loan Receivables	Loan Receivables The Company has two loan portfolio segments: credit card loans and other loans. The Company's classes of receivables within the two portfolio segments are depicted in the following table (dollars in millions): September 30, December 31, Credit card loans (1)(2) $ 70,320 $ 71,472 Other loans (3) Private student loans (4) 10,184 9,954 Personal loans 6,890 7,177 Other loans 2,148 1,846 Total other loans 19,222 18,977 Total loan receivables 89,542 90,449 Allowance for credit losses (6,861) (8,226) Net loan receivables $ 82,681 $ 82,223 (1) Amounts include carrying values of $12.9 billion and $16.7 billion underlying investors' interest in trust debt at September 30, 2021 and December 31, 2020, respectively, and $11.6 billion and $10.6 billion in seller's interest at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information. (2) Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $379 million and $420 million at September 30, 2021 and December 31, 2020, respectively. (3) Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $503 million, $41 million and $6 million, respectively, at September 30, 2021 and $469 million, $49 million and $6 million, respectively, at December 31, 2020. (4) Amounts include carrying values of $215 million and $250 million in loans pledged as collateral against the notes issued from a private student loan securitization trust at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information. Credit Quality Indicators As part of credit risk management activities, on an ongoing basis, the Company reviews information related to the performance of a customer's account with the Company and information from credit bureaus, such as FICO or other credit scores, relating to the customer's broader credit performance. The Company actively monitors key credit quality indicators, including FICO scores and delinquency status, for credit card, private student and personal loans. These indicators are important to understand the overall credit performance of the Company's customers and their ability to repay. FICO scores are generally obtained at the origination of the account and are refreshed monthly or quarterly thereafter to assist in predicting customer behavior. Historically, the Company has noted that accounts with FICO scores below 660 have larger delinquencies and credit losses than those with higher credit scores. The following table provides the distribution of the amortized cost basis (excluding accrued interest receivable presented in other assets) by the most recent FICO scores available for the Company's customers for credit card, private student and personal loan receivables (dollars in millions): Credit Risk Profile by FICO Score September 30, 2021 December 31, 2020 660 and Above Less than 660 660 and Above Less than 660 $ % $ % $ % $ % Credit card loans (1) $ 59,005 84 % $ 11,315 16 % $ 58,950 82 % $ 12,522 18 % Private student loans by origination year (2)(3) 2021 $ 1,011 94 % $ 70 6 % 2020 1,593 97 % 54 3 % $ 1,173 95 % $ 60 5 % 2019 1,485 96 % 56 4 % 1,659 96 % 61 4 % 2018 1,185 95 % 58 5 % 1,365 96 % 61 4 % 2017 898 95 % 52 5 % 1,052 95 % 57 5 % Prior 3,521 95 % 201 5 % 4,219 94 % 247 6 % Total private student loans $ 9,693 95 % $ 491 5 % $ 9,468 95 % $ 486 5 % Personal loans by origination year 2021 $ 2,541 99 % $ 18 1 % 2020 1,921 98 % 37 2 % $ 2,880 99 % $ 25 1 % 2019 1,291 95 % 66 5 % 2,183 96 % 90 4 % 2018 550 92 % 51 8 % 1,018 92 % 90 8 % 2017 276 88 % 36 12 % 558 89 % 69 11 % Prior 87 84 % 16 16 % 227 86 % 37 14 % Total personal loans $ 6,666 97 % $ 224 3 % $ 6,866 96 % $ 311 4 % (1) Amounts include $881 million and $1.0 billion of revolving line-of-credit arrangements that were converted to term loans as a result of a troubled debt restructuring ("TDR") program as of September 30, 2021 and December 31, 2020, respectively. (2) A majority of private student loan originations occur in the third quarter and disbursements can span multiple calendar years. (3) FICO score represents the higher credit score of the cosigner or borrower. Delinquencies are an indicator of credit quality at a point in time. A loan balance is considered delinquent when contractual payments on the loan become 30 days past due. The amortized cost basis (excluding accrued interest receivable presented in other assets) of delinquent loans in the Company's loan portfolio is shown below for credit card, private student and personal loan receivables (dollars in millions): September 30, 2021 December 31, 2020 30-89 Days 90 or Total Past 30-89 Days 90 or Total Past Credit card loans $ 573 $ 467 $ 1,040 $ 739 $ 739 $ 1,478 Private student loans by origination year (1) 2021 $ — $ — $ — 2020 4 1 5 $ — $ — $ — 2019 11 2 13 3 1 4 2018 14 4 18 9 3 12 2017 15 5 20 12 4 16 Prior 78 24 102 86 20 106 Total private student loans $ 122 $ 36 $ 158 $ 110 $ 28 $ 138 Personal loans by origination year 2021 $ 2 $ — $ 2 2020 7 2 9 $ 5 $ 2 $ 7 2019 12 5 17 18 9 27 2018 8 3 11 15 7 22 2017 5 2 7 10 5 15 Prior 2 1 3 5 2 7 Total personal loans $ 36 $ 13 $ 49 $ 53 $ 25 $ 78 (1) Private student loans may include a deferment period, during which customers are not required to make payments while enrolled in school at least half time as determined by the school. During a deferment period, these loans do not advance into delinquency. Allowance for Credit Losses The following tables provide changes in the Company's allowance for credit losses (dollars in millions): For the Three Months Ended September 30, 2021 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at June 30, 2021 $ 5,409 $ 828 $ 745 $ 44 $ 7,026 Additions Provision for credit losses (1) 178 46 (64) — 160 Deductions Charge-offs (495) (23) (38) — (556) Recoveries 206 6 19 — 231 Net charge-offs (289) (17) (19) — (325) Balance at September 30, 2021 $ 5,298 $ 857 $ 662 $ 44 $ 6,861 For the Three Months Ended September 30, 2020 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at June 30, 2020 $ 6,491 $ 799 $ 857 $ 37 $ 8,184 Additions Provision for credit losses (1) 604 55 49 2 710 Deductions Charge-offs (759) (20) (62) (1) (842) Recoveries 155 6 13 — 174 Net charge-offs (604) (14) (49) (1) (668) Balance at September 30, 2020 $ 6,491 $ 840 $ 857 $ 38 $ 8,226 For the Nine Months Ended September 30, 2021 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at December 31, 2020 $ 6,491 $ 840 $ 857 $ 38 $ 8,226 Additions Provision for credit losses (1) (18) 61 (96) 6 (47) Deductions Charge-offs (1,778) (63) (150) — (1,991) Recoveries 603 19 51 — 673 Net charge-offs (1,175) (44) (99) — (1,318) Balance at September 30, 2021 $ 5,298 $ 857 $ 662 $ 44 $ 6,861 For the Nine Months Ended September 30, 2020 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at December 31, 2019 (2) $ 2,883 $ 148 $ 348 $ 4 $ 3,383 Cumulative effect of ASU No. 2016-13 adoption (3) 1,667 505 265 24 2,461 Balance at January 1, 2020 4,550 653 613 28 5,844 Additions Provision for credit losses (1) 3,916 233 426 11 4,586 Deductions Charge-offs (2,480) (62) (224) (1) (2,767) Recoveries 505 16 42 — 563 Net charge-offs (1,975) (46) (182) (1) (2,204) Balance at September 30, 2020 $ 6,491 $ 840 $ 857 $ 38 $ 8,226 (1) Excludes a $25 million and $40 million reclassification of the liability for expected credit losses on unfunded commitments for the three months ended September 30, 2021 and 2020, respectively, and $2 million and $17 million for the nine months ended September 30, 2021 and 2020, respectively, as the liability is recorded in accrued expenses and other liabilities in the Company's condensed consolidated statements of financial condition. (2) Prior to the adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. (3) Represents the adjustment to the allowance for credit losses due to the adoption of ASU No. 2016-13 on January 1, 2020. The allowance for credit losses was approximately $6.9 billion at September 30, 2021, which reflects a $165 million release from the amount of the allowance for credit losses at June 30, 2021 and a $1.4 billion release from the amount of the allowance for credit losses at December 31, 2020. The release in the allowance for credit losses between September 30, 2021 and June 30, 2021, was primarily driven by improving macroeconomic forecasts and continued stable credit performance, partially offset by modest loan growth during the period. The modest growth in loan receivables during the three months ended September 30, 2021, was driven by the robust credit card sales trends as coronavirus disease 2019 ("COVID-19") restrictions continue to ease and the United States economy continues to more fully reopen. Additionally, credit card sales from new accounts and seasonality in private student loan originations contributed to an increase in ending outstanding loan receivables. The loan receivables growth was partially offset by elevated payment rates resulting from the several rounds of government stimulus and associated improvement in household cash flows. The release in the allowance for credit losses between September 30, 2021 and December 31, 2020, was primarily driven by improvements in the macroeconomic forecast and continued stable credit performance. The release was also partially driven by a moderate reduction in loan receivables outstanding during the period. The decrease in outstanding loan receivables, particularly credit card and personal loan receivables, and the stable credit performance, were driven by elevated payment rates resulting from the several rounds of government stimulus and associated improvement in household cash flows. The decrease in outstanding loan receivables was partially offset by the robust credit card sales trends during the period and seasonality in private student loan originations in the third quarter of 2021. In estimating the allowance at September 30, 2021, the Company used a macroeconomic forecast that projected (i) a peak unemployment rate of 6.1%, decreasing to 5.5% and 4.0% through the end of 2021 and 2022, respectively; and (ii) a 6.4% and 3.5% annualized growth in the real gross domestic product for 2021 and 2022, respectively. Labor market conditions, which historically have been an important determinant of credit loss trends, continue to improve despite the spread of the COVID-19 delta variant. However, the unemployment rate and initial and continuing jobless claims remain moderately elevated relative to pre-pandemic levels. In estimating expected credit losses, the Company considered the uncertainties associated with borrower behavior, payment trends and credit performance subsequent to the expiration of government stimulus programs, such as the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") and the American Rescue Plan Act of 2021 ("ARPA"), and disaster relief programs, such as foreclosure moratoriums and federal student loan and mortgage payment forbearance. During the third quarter of 2021, several disaster relief programs expired or were rescinded entirely. As the government's response to the pandemic wanes, there is uncertainty regarding the sustainability of the recent credit quality trends in the Company's loan receivables portfolio. Accordingly, the estimation of the allowance for credit losses has required significant management judgment. Company-initiated loan modification programs include those specifically offered in response to the COVID-19 pandemic as well as existing programs offered to customers experiencing difficulty making their payments. In addition to the Skip-a-Pay (payment deferral) ("SaP") programs, which ended on August 31, 2020, the Company has other modification programs that customers have utilized during the period related to the pandemic. The Company evaluated the accounts using these modifications as a result of the COVID-19 pandemic for potential exclusion from the TDR designation either due to the insignificance of the concession or because they qualified for an exemption pursuant to the CARES Act. The effects of all modifications, including TDRs, loan modifications exempt from the TDR designation pursuant to the CARES Act and SaP programs, are considered as part of the process for determining the allowance for credit losses. The forecast period the Company deemed reasonable and supportable was 18 months for all periods presented except March 31, 2020, where the forecast period was 12 months due to the uncertainty caused by the rapidly changing economic environment experienced at the onset of the COVID-19 pandemic. The 18-month reasonable and supportable forecast period was deemed appropriate based on the observed economic phase transition from recovery to expansion and the associated stabilization of macroeconomic forecasts. For all periods presented, the Company determined that a reversion period of 12 months was appropriate for similar reasons. Due to the uncertainties associated with borrower behavior resulting from government stimulus and disaster relief programs, the Company applied a weighted reversion method to provide a more reasonable transition to historical losses for all loan products for all periods presented with the following exceptions: at March 31, 2020 and December 31, 2019, the Company applied a straight-line method for all loan products. At June 30, 2020, the Company applied a weighted reversion method for credit card loans and a straight-line method for all other loan products. The decrease in net charge-offs for credit card and personal loans for the three and nine months ended September 30, 2021, when compared to the same periods in 2020, was primarily due to the impacts of government stimulus and disaster relief programs and to a lesser extent improved collection and recovery strategies. Additionally, the decrease in net charge- offs of personal loans for the three and nine months ended September 30, 2021, were favorably impacted by tighter underwriting standards that were implemented in early 2020. Net charge-offs for private student loans remained relatively flat for the three and nine months ended September 30, 2021, when compared to the same period in 2020, due to the impacts of government stimulus and disaster relief programs. Net charge-offs of principal are recorded against the allowance for credit losses, as shown in the preceding table. Information regarding net charge-offs of interest and fee revenues on credit card and other loans is as follows (dollars in millions): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Interest and fees accrued subsequently charged-off, net of recoveries (recorded as a reduction of interest income) $ 57 $ 114 $ 232 $ 393 Fees accrued subsequently charged-off, net of recoveries (recorded as a reduction to other income) $ 15 $ 27 $ 59 $ 95 Delinquent and Non-Accruing Loans The amortized cost basis (excluding accrued interest receivable presented in other assets) of delinquent and non-accruing loans in the Company's loan portfolio is shown below for each class of loan receivables (dollars in millions): 30-89 Days 90 or Total Past 90 or Total Non-accruing (1) At September 30, 2021 Credit card loans $ 573 $ 467 $ 1,040 $ 430 $ 201 Other loans Private student loans 122 36 158 35 8 Personal loans 36 13 49 12 9 Other loans 5 6 11 2 14 Total other loans 163 55 218 49 31 Total loan receivables $ 736 $ 522 $ 1,258 $ 479 $ 232 At December 31, 2020 Credit card loans $ 739 $ 739 $ 1,478 $ 687 $ 209 Other loans Private student loans 110 28 138 27 12 Personal loans 53 25 78 23 12 Other loans 8 3 11 — 10 Total other loans 171 56 227 50 34 Total loan receivables $ 910 $ 795 $ 1,705 $ 737 $ 243 (1) The Company estimates that the gross interest income that would have been recorded under the original terms of non-accruing credit card loans was $6 million and $7 million for the three months ended September 30, 2021 and 2020, respectively, and $21 million and $25 million for the nine months ended September 30, 2021 and 2020, respectively. The Company does not separately track the amount of gross interest income that would have been recorded under the original terms of loans. Instead, the Company estimated this amount based on customers' current balances and most recent interest rates. Troubled Debt Restructurings The Company has internal loan modification programs that provide relief to credit card, private student and personal loan borrowers who may be experiencing financial hardship. The Company considers a modified loan in which a concession has been granted to the borrower to be a TDR based on the cumulative length of the concession period and credit quality of the borrower. The Company evaluates new programs to determine which of them meet the definition of a TDR, including modification programs provided to customers for temporary relief due to the economic impacts of the COVID-19 pandemic. The internal loan modification programs include both temporary and permanent programs, which vary by product. External loan modification programs are also available for credit card and personal loans. All loans modified in a temporary modification program, including those specifically created in response to the COVID-19 pandemic, are evaluated for exclusion from the TDR designation either due to the insignificance of the concession or because they qualify for exemption pursuant to the CARES Act. To the extent the loan accounts do not meet the requirements for exclusion, temporary and permanent modifications on credit card and personal loans, as well as temporary modifications on private student loans and certain grants of private student loan forbearance, result in the loans being classified as TDRs. In addition, loans that defaulted from, or successfully completed a loan modification program or forbearance, continue to be classified as TDRs, except as noted below. See the table below that presents the carrying value of loans that experienced a payment default during the period for more information. For credit card customers, the Company offers both temporary and permanent hardship programs. The temporary hardship programs consist of an interest rate reduction and, in some cases, a reduced minimum payment, both lasting for a period no longer than 12 months. Charging privileges on these accounts are generally suspended while in the program. However, if the customer meets certain criteria, charging privileges may be reinstated following completion of the program. Credit card accounts of borrowers who have previously participated in a temporary interest rate reduction program and have both demonstrated financial stability and had their charging privileges reinstated at a market-based interest rate, are excluded from the balance of TDRs. The permanent modification program involves closing the account, changing the loan structure to a fixed payment loan with a maturity no longer than 72 months and reducing the interest rate on the loan. The permanent modification program does not typically provide for the forgiveness of unpaid principal but may allow for the reversal of certain unpaid interest or fee assessments. The Company also makes permanent loan modifications for customers who request financial assistance through external sources, such as a consumer credit counseling agency program. These loans typically receive a reduced interest rate, typically continue to be subject to the original minimum payment terms and do not normally include waiver of unpaid principal, interest or fees. These permanent loan modifications remain in the population of TDRs until they are paid off or charged off. At September 30, 2021 and December 31, 2020, there were $5.3 billion and $5.7 billion, respectively, of private student loans in repayment and $63 million and $117 million, respectively, in forbearance. To assist private student loan borrowers who are experiencing temporary financial difficulties but are willing to resume making payments, the Company may offer hardship forbearance, payment deferral, a temporary payment reduction, a temporary interest rate reduction or extended terms. A modified loan typically meets the definition of a TDR based on the cumulative length of the concession period and a determination of financial distress based on an evaluation of the borrower's credit quality using FICO scores. For personal loan customers, the Company offers various payment programs, including temporary and permanent programs, in certain situations. The temporary programs normally consist of reducing the minimum payment for no longer than 12 months. Further, the interest rate on the loan is reduced in certain circumstances. The permanent programs involve extending the loan term and, in certain circumstances, reducing the interest rate on the loan. The total term of the loan, including modification, may not exceed nine years. The Company also allows permanent loan modifications for customers who request financial assistance through external sources, similar to the credit card customers discussed above. Payments are modified based on the new terms agreed upon with the credit counseling agency. Personal loans included in temporary and permanent programs are classified as TDRs. The Company monitors borrower performance after using payment programs or forbearance. The Company believes the programs are useful in assisting customers experiencing financial difficulties and allowing them to make timely payments. In addition to helping customers with their credit needs, these programs are designed to maximize collections and ultimately the Company’s profitability. The Company plans to continue to use payment programs and forbearance to provide relief to customers experiencing temporary financial difficulties and expects to have additional loans classified as TDRs in the future as a result. To evaluate the primary financial effects that resulted from credit card loans entering into a TDR program during the three and nine months ended September 30, 2021 and 2020, the Company quantified the amount by which interest and fees were reduced during the periods. During the three months ended September 30, 2021 and 2020, the Company forgave approximately $7 million and $13 million, respectively, of interest and fees resulting from accounts entering into a credit card loan TDR program. During the nine months ended September 30, 2021 and 2020, the Company forgave approximately $28 million and $52 million, respectively, of interest and fees resulting from accounts entering into a credit card loan TDR program. For all loan products, interest income on modified loans is recognized based on the modified contractual terms. Section 4013 of the CARES Act provides certain financial institutions with the option to suspend the application of accounting and reporting guidance for TDRs for a limited period of time for loan modifications made to address the effects of the COVID-19 pandemic. Section 541 of the Omnibus and COVID Relief and Response Act extended the loan modification relief provided by the CARES Act through the earlier of January 1, 2022, or the date that is 60 days after the termination of the presidentially-declared national emergency. The Company has elected to apply the option to suspend the application of accounting guidance for TDRs as provided under Section 4013 of the CARES Act and as subsequently extended. As such, TDR program balances and the number of accounts have been favorably impacted by the exclusion of certain modifications from the TDR designation pursuant to these exemptions and are expected to remain lower than they otherwise would have been. The following table provides information on loans that entered a TDR program during the period (dollars in millions): For the Three Months Ended September 30, 2021 2020 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 13,964 $ 86 20,779 $ 150 Private student loans 102 $ 2 118 $ 2 Personal loans 888 $ 10 2,505 $ 33 For the Nine Months Ended September 30, 2021 2020 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 48,887 $ 315 130,869 $ 875 Private student loans 355 $ 7 1,767 $ 32 Personal loans 3,102 $ 38 6,315 $ 83 (1) Accounts that entered a credit card TDR program include $72 million and $143 million that were converted from revolving line-of-credit arrangements to term loans during the three months ended September 30, 2021 and 2020, respectively, and $288 million and $529 million for the nine months ended September 30, 2021 and 2020, respectively. The number and balance of new credit card and personal loan modifications, including the combined total of those identified as TDRs and those exempt from the TDR designation, decreased during the three and nine months ended September 30, 2021, when compared to the same periods in 2020. The decrease in both periods is primarily due to the impacts of several rounds of government stimulus and disaster relief programs, which reduced the need for customers to enroll in a loan modification program. The number and balance of loan modifications across all products, including the combined total of those identified as TDRs and those exempt from the TDR designation, during the three and nine months ended September 30, 2020, were favorably impacted by the utilization of SaP programs in lieu of traditional loan modification programs. Additionally, enrollments in personal loan modification programs were favorably impacted by tighter underwriting standards that were implemented in early 2020. The following table presents the carrying value of loans that experienced a default during the period that had been modified in a TDR during the 15 months preceding the end of each period (dollars in millions): For the Three Months Ended September 30, 2021 2020 Number of Accounts Aggregated Outstanding Balances Upon Default Number of Accounts Aggregated Outstanding Balances Upon Default TDRs that subsequently defaulted Credit card loans (1)(2) 3,679 $ 21 8,983 $ 52 Private student loans (3) 83 $ 2 272 $ 6 Personal loans (2) 399 $ 6 624 $ 9 For the Nine Months Ended September 30, 2021 2020 Number of Accounts Aggregated Outstanding Balances Upon Default Number of Accounts Aggregated Outstanding Balances Upon Default TDRs that subsequently defaulted Credit card loans (1)(2) 14,205 $ 84 41,285 $ 235 Private student loans (3) 214 $ 5 876 $ 18 Personal loans (2) 1,287 $ 18 2,446 $ 36 (1) For credit card loans that default from a temporary program, accounts revert to the pre-modification terms and charging privileges remain suspended in most cases. (2) For credit card loans and personal loans, a customer defaults from a loan modification program after either two consecutive missed payments or at charge-off, depending on the program. The outstanding balance upon default is generally the loan balance at the end of the month prior to default. (3) For student loans, a customer defaults from a loan modification after they are 60 or more days delinquent. The outstanding balance upon default is generally the loan balance at the end of the month prior to default. Of the account balances that defaulted as shown above for the three months ended September 30, 2021 and 2020, approximately 62% and 65%, respectively, and for the nine months ended September 30, 2021 and 2020, approximately 66% and 52%, respectively, of the total balances were charged off at the end of the month in which they defaulted from a TDR program. For accounts that have defaulted from a TDR program and have not been subsequently charged off, the balances are included in the allowance for credit loss analysis discussed above under “— Allowance for Credit Losses.”

Credit Card and Private Student

Credit Card and Private Student Loan Securitization Activities	9 Months Ended
	Sep. 30, 2021
Variable Interest Entities Disclosure [Abstract]
Credit Card and Private Student Loan Securitization Activities	Credit Card and Private Student Loan Securitization Activities The Company's securitizations are accounted for as secured borrowings and the related trusts are treated as consolidated subsidiaries of the Company. For a description of the Company's principles of consolidation with respect to VIEs, see Note 1: Background and Basis of Presentation to the consolidated financial statements in the Company's annual report on Form 10-K for the year ended December 31, 2020. Credit Card Securitization Activities The Company accesses the term asset securitization market through the Discover Card Master Trust I ("DCMT") and the Discover Card Execution Note Trust ("DCENT"). Credit card loan receivables are transferred into DCMT and beneficial interests in DCMT are transferred into DCENT. DCENT issues debt securities to investors that are reported in long-term borrowings. The DCENT debt structure consists of four classes of securities (DiscoverSeries Class A, B, C and D notes), with the most senior class generally receiving a triple-A rating. To issue senior, higher-rated classes of notes, it is necessary to obtain the appropriate amount of credit enhancement, generally through the issuance of junior, lower-rated or more highly subordinated classes of notes. Wholly-owned subsidiaries of Discover Bank hold the subordinated classes of notes. The Company is exposed to credit risk associated with trust receivables as of the balance sheet date through the retention of these subordinated interests. The current expected credit loss ("CECL") on trust receivables is included in the allowance for credit losses estimate. The Company's retained interests in the trust's assets, consisting of investments in DCENT notes held by subsidiaries of Discover Bank, constitute intercompany positions that are eliminated in the preparation of the Company's condensed consolidated statements of financial condition. Upon transfer of credit card loan receivables to the trust, the receivables and certain cash flows derived from them become restricted for use in meeting obligations to the trust's creditors. Further, the transferred credit card loan receivables are owned by the trust and are not available to the Company's third-party creditors. The trusts have ownership of cash balances, which are reported in restricted cash within the Company's condensed consolidated statements of financial condition. Except for the seller's interest in trust receivables, the Company's interests in trust assets are generally subordinate to the interests of third-party investors in trust debt and, as such, may not be realized by the Company if needed to absorb deficiencies in cash flows that are allocated to those investors. Apart from the restricted assets related to securitization activities, the investors and the securitization trusts have no recourse to the Company's other assets or the Company's general credit for a shortage in cash flows. The carrying values of these restricted assets, which are presented on the Company's condensed consolidated statements of financial condition as relating to securitization activities, are shown in the following table (dollars in millions): September 30, December 31, Restricted cash $ 23 $ 16 Investors' interests held by third-party investors 8,925 10,600 Investors' interests held by wholly-owned subsidiaries of Discover Bank 3,971 6,121 Seller's interest 11,640 10,575 Loan receivables (1) 24,536 27,296 Allowance for credit losses allocated to securitized loan receivables (1) (1,436) (1,936) Net loan receivables 23,100 25,360 Other 3 3 Carrying value of assets of consolidated variable interest entities $ 23,126 $ 25,379 (1) The Company maintains its allowance for credit losses at an amount equal to lifetime expected credit losses associated with all loan receivables, which includes all loan receivables in the trusts. Therefore, the credit risk associated with the transferred receivables is fully reflected on the Company's statements of financial condition in accordance with GAAP. The debt securities issued by the consolidated trusts are subject to credit, payment and interest rate risks on the transferred credit card loan receivables. To protect investors in the securities, certain features or triggering events will cause an early amortization of the debt securities, including triggers related to the impact of the performance of the trust receivables on the availability and adequacy of cash flows to meet contractual requirements. As of September 30, 2021, no economic or other early amortization events have occurred. The Company continues to own and service the accounts that generate the loan receivables held by the trusts. Discover Bank receives servicing fees from the trusts based on a percentage of the monthly investor principal balance outstanding. Although the fee income to Discover Bank offsets the fee expense to the trusts and thus is eliminated in consolidation, failure to service the transferred loan receivables in accordance with contractual requirements could lead to a termination of the servicing rights and the loss of future servicing income, net of related expenses. Private Student Loan Securitization Activities Private student loan trust receivables are reported in loan receivables and the related debt issued by the trust is reported in long-term borrowings. The trust assets are restricted from being sold or pledged as collateral for other borrowings and the cash flows from these restricted assets may be used only to pay obligations of the trusts. Except for the trust's restricted assets, the trust and investors have no recourse to the Company's other assets or the Company's general credit for a shortage in cash flows. Principal payments on the long-term secured borrowings are made as cash is collected on the underlying loans that are collateral on the secured borrowings. The Company does not have access to cash collected by the securitization trust until cash is released in accordance with the trust indenture agreement. Similar to the credit card securitizations, the Company continues to service the private student loan receivables held by the trust and receives servicing fees from the trust based on a percentage of the principal balance outstanding. Although the servicing fee income offsets the fee expense related to the trust and thus is eliminated in consolidation, failure to service the transferred loan receivables in accordance with contractual requirements could lead to a termination of the servicing rights and the loss of future servicing income, net of related expenses. Under terms of the trust arrangement, the Company has the option, but not the obligation, to provide financial support to the trust, but has never provided such support. A substantial portion of the credit risk associated with the securitized loans has been transferred to a third party under an indemnification arrangement. The carrying values of these restricted assets, which are presented on the Company's condensed consolidated statements of financial condition as relating to securitization activities, are shown in the following table (dollars in millions): September 30, December 31, Restricted cash $ 9 $ 9 Private student loan receivables 215 250 Carrying value of assets of consolidated variable interest entities $ 224 $ 259

Intangible Assets (Notes)

Intangible Assets (Notes)	9 Months Ended
	Sep. 30, 2021
Intangible Assets [Abstract]
Intangible Assets	Intangible Assets In the second quarter of 2020, the Company conducted an interim impairment test on its non-amortizable intangible assets, both the Diners Club trade names and international transaction processing rights, due to changes in the international travel and entertainment businesses and a declining revenue outlook for the foreseeable future resulting from the COVID-19 pandemic. The valuation methodology used to value the trade names and international transaction processing rights was based on a discounted cash flow method, consistent with the methods used for annual impairment testing. As a result of this analysis, the Company determined that the trade names and international transaction processing rights were impaired and recognized charges, in the second quarter of 2020, in its Payment Services segment of $36 million and $23 million, respectively. The impairments were recorded in other expense. In the second quarter of 2021, global travel and entertainment spending continued to trend lower than pre-pandemic levels. As a result, the Company re-evaluated that impact on the value of the Diners Club trade names by conducting an interim impairment test on the asset in conjunction with the preparation of the financial statements. The valuation methodology used to value the trade names was based on a discounted cash flow method, consistent with the methods used for annual impairment testing. As a result of this analysis, the Company determined that the trade names were fully impaired and recognized a charge, in the second quarter of 2021, in its Payment Services segment of $92 million. The impairment was recorded in other expense. At September 30, 2021, the trade names and the international transaction processing rights have no remaining net book value.

Deposits

Deposits	9 Months Ended
	Sep. 30, 2021
Deposits [Abstract]
Deposits	Deposits The Company offers its deposit products to customers through two channels: (i) through direct marketing, internet origination and affinity relationships ("direct-to-consumer deposits"); and (ii) indirectly through contractual arrangements with securities brokerage firms ("brokered deposits"). Direct-to-consumer deposits include online savings accounts, certificates of deposit, money market accounts, IRA savings accounts, IRA certificates of deposit and checking/debit accounts. Brokered deposits include certificates of deposit and sweep accounts. The following table provides a summary of interest-bearing deposit accounts (dollars in millions): September 30, December 31, Certificates of deposit in amounts less than $100,000 $ 14,592 $ 19,105 Certificates of deposit in amounts $100,000 or greater (1) 7,239 9,164 Savings deposits, including money market deposit accounts 49,295 47,426 Total interest-bearing deposits $ 71,126 $ 75,695 (1) Includes $2.0 billion and $2.6 billion in certificates of deposit equal to or greater than $250,000, the Federal Deposit Insurance Corporation ("FDIC") insurance limit, as of September 30, 2021 and December 31, 2020, respectively. The following table summarizes certificates of deposit in amounts of $100,000 or greater by contractual maturity (dollars in millions): September 30, Three months or less $ 1,458 Over three months through six months 1,640 Over six months through twelve months 2,711 Over twelve months 1,430 Total $ 7,239 The following table summarizes certificates of deposit maturing over the remainder of this year, over each of the next four years and thereafter (dollars in millions): September 30, 2021 $ 4,171 2022 11,133 2023 2,663 2024 1,451 2025 870 Thereafter 1,543 Total $ 21,831

Long-Term Borrowings

Long-Term Borrowings	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Long-Term Borrowings	Long-Term Borrowings Long-term borrowings consist of borrowings having original maturities of one year or more. The following table provides a summary of the Company's long-term borrowings and weighted-average interest rates on outstanding balances (dollars in millions): September 30, 2021 December 31, 2020 Maturity Interest Weighted-Average Interest Rate Outstanding Amount Outstanding Amount Securitized Debt Fixed-rate asset-backed securities (1) 2022-2026 0.58% - 3.04% 2.01% $ 5,607 $ 6,041 Floating-rate asset-backed securities (2) 2022-2024 0.41% - 0.68% 0.54% 3,347 4,669 Total Discover Card Master Trust I and Discover Card Execution Note Trust 8,954 10,710 Floating-rate asset-backed security (3)(4) 2031 4.25% 4.25% 110 130 Total private student loan securitization trust 110 130 Total long-term borrowings - owed to securitization investors 9,064 10,840 Discover Financial Services (Parent Company) Fixed-rate senior notes 2022-2027 3.75% - 5.20% 4.16% 3,370 3,337 Fixed-rate retail notes 2022-2031 2.85% - 4.40% 3.75% 166 336 Discover Bank Fixed-rate senior bank notes (1) 2023-2030 2.45% - 4.65% 3.63% 5,406 6,213 Fixed-rate subordinated bank notes (1) 2028 4.68% 4.68% 510 515 Total long-term borrowings $ 18,516 $ 21,241 (1) The Company uses interest rate swaps to hedge portions of these long-term borrowings against changes in fair value attributable to changes in the London Interbank Offered Rate ("LIBOR") or Overnight Index Swap ("OIS") Rate. The use of these interest rate swaps impacts the carrying value of the debt. See Note 16: Derivatives and Hedging Activities. (2) DCENT floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month LIBOR + 33 to 60 basis points as of September 30, 2021. (3) The private student loan securitization trust floating-rate asset-backed security includes an issuance with the following interest rate term: Prime rate + 100 basis points as of September 30, 2021. (4) Repayment of this debt depends on the timing of principal and interest payments on the underlying private student loans. The date shown represents the final maturity date. The following table summarizes long-term borrowings maturing over the remainder of this year, over each of the next four years and thereafter (dollars in millions): September 30, 2021 2021 $ — 2022 5,188 2023 3,324 2024 3,738 2025 529 Thereafter 5,737 Total $ 18,516 The Company has access to committed borrowing capacity through private securitizations to support the funding of its credit card loan receivables. As of September 30, 2021, the total commitment of secured credit facilities through private providers was $4.0 billion, none of which was drawn as of September 30, 2021. Access to the unused portions of the secured credit facilities is subject to the terms of the agreements with each of the providers. The secured credit facilities have various expirations in 2023. Borrowings outstanding under each facility bear interest at a margin above LIBOR or the asset-backed commercial paper costs of each provider. The terms of each agreement provide for a commitment fee to be paid on the unused capacity and include various affirmative and negative covenants, including performance metrics and legal requirements similar to those required to issue any term securitization transaction.

Preferred Stock (Notes)

Preferred Stock (Notes)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Preferred Stock	Preferred Stock The table below presents a summary of the Company's non-cumulative perpetual preferred stock that is outstanding at September 30, 2021 (dollars in millions, except per depositary share amounts): Series Description Initial Issuance Date Liquidation Preference and Redemption Price per Depositary Share (1) Per Annum Dividend Rate in effect at September 30, 2021 Total Depositary Shares Authorized, Issued and Outstanding Carrying Value September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 C (2)(3)(4) Fixed-to-Floating Rate 10/31/2017 $ 1,000 5.500 % 570,000 570,000 $ 563 $ 563 D (2)(5)(6) Fixed-Rate Reset 6/22/2020 $ 1,000 6.125 % 500,000 500,000 493 493 Total Preferred Stock 1,070,000 1,070,000 $ 1,056 $ 1,056 (1) Redeemable at the redemption price plus declared and unpaid dividends. (2) Issued as depositary shares, each representing 1/100 th interest in a share of the corresponding series of preferred stock. Each preferred share has a par value of $0.01. (3) Redeemable at the Company’s option, subject to regulatory approval, either (i) in whole or in part on any dividend payment date on or after October 30, 2027, or (ii) in whole but not in part, at any time within 90 days following a regulatory capital treatment event (as defined in the certificate of designations for the Series C preferred stock). (4) Any dividends declared are payable semi-annually in arrears at a rate of 5.50% per annum until October 30, 2027. Thereafter, dividends declared will be payable quarterly in arrears at a floating rate equal to 3-month LIBOR plus a spread of 3.076% per annum. (5) Redeemable at the Company’s option, subject to regulatory approval, either (i) in whole or in part during the three-month period prior to, and including, each reset date (as defined in the certificate of designations for the Series D preferred stock) or (ii) in whole but not in part, at any time within 90 days following a regulatory capital treatment event (as defined in the certificate of designations for the Series D Preferred Stock). (6) Any dividends declared are payable semi-annually in arrears at a rate of 6.125% per annum until September 23, 2025, after which the dividend rate will reset every five years to a fixed annual rate equal to the 5-year Treasury plus a spread of 5.783%.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income Changes in each component of accumulated other comprehensive income ("AOCI") were as follows (dollars in millions): Unrealized Gains on Available-for-Sale Investment Securities, Net of Tax Losses on Cash Flow Hedges, Net of Tax Losses on Pension Plan, Net of Tax AOCI For the Three Months Ended September 30, 2021 Balance at June 30, 2021 $ 198 $ (10) $ (227) $ (39) Net change (29) — — (29) Balance at September 30, 2021 $ 169 $ (10) $ (227) $ (68) For the Three Months Ended September 30, 2020 Balance at June 30, 2020 $ 352 $ (16) $ (214) $ 122 Net change (32) 3 — (29) Balance at September 30, 2020 $ 320 $ (13) $ (214) $ 93 For the Nine Months Ended September 30, 2021 Balance at December 31, 2020 $ 284 $ (12) $ (227) $ 45 Net change (115) 2 — (113) Balance at September 30, 2021 $ 169 $ (10) $ (227) $ (68) For the Nine Months Ended September 30, 2020 Balance at December 31, 2019 $ 112 $ (17) $ (214) $ (119) Net change 208 4 — 212 Balance at September 30, 2020 $ 320 $ (13) $ (214) $ 93 The following table presents each component of other comprehensive income ("OCI") before reclassifications and amounts reclassified from AOCI for each component of OCI before- and after-tax (dollars in millions): Before Tax Tax Benefit (Expense) Net of Tax For the Three Months Ended September 30, 2021 Available-for-Sale Investment Securities Net unrealized holding losses arising during the period $ (38) $ 9 $ (29) Net change $ (38) $ 9 $ (29) Cash Flow Hedges Net unrealized gains arising during the period $ — $ 1 $ 1 Amounts reclassified from AOCI — (1) (1) Net change $ — $ — $ — For the Three Months Ended September 30, 2020 Available-for-Sale Investment Securities Net unrealized holding losses arising during the period $ (42) $ 10 $ (32) Net change $ (42) $ 10 $ (32) Cash Flow Hedges Amounts reclassified from AOCI $ 4 $ (1) $ 3 Net change $ 4 $ (1) $ 3 For the Nine Months Ended September 30, 2021 Available-for-Sale Investment Securities Net unrealized holding losses arising during the period $ (152) $ 37 $ (115) Net change $ (152) $ 37 $ (115) Cash Flow Hedges Net unrealized gains arising during the period $ — $ 1 $ 1 Amounts reclassified from AOCI 2 (1) 1 Net change $ 2 $ — $ 2 For the Nine Months Ended September 30, 2020 Available-for-Sale Investment Securities Net unrealized holding gains arising during the period $ 275 $ (67) $ 208 Net change $ 275 $ (67) $ 208 Cash Flow Hedges Net unrealized losses arising during the period $ (7) $ 3 $ (4) Amounts reclassified from AOCI 11 (3) 8 Net change $ 4 $ — $ 4

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The following table presents the calculation of the Company's effective income tax rate (dollars in millions): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Income before income taxes $ 1,402 $ 959 $ 5,703 $ 420 Income tax expense $ 311 $ 188 $ 1,321 $ 78 Effective income tax rate 22.2 % 19.6 % 23.2 % 18.6 % Income tax expense increased $123 million and $1.2 billion for the three and nine months ended September 30, 2021, respectively, as compared to the same periods in 2020. The increase in income tax expense was primarily driven by an increase in pretax income. The effective tax rate increased for the three and nine months ended September 30, 2021, respectively, as compared to the same periods in 2020, primarily due to tax credits having a lower rate benefit on higher pretax income. The Company is subject to examination by the Internal Revenue Service ("IRS") and tax authorities in various state, local and foreign tax jurisdictions. The IRS is examining the Company's 2018 federal income tax filings. The Company regularly assesses the likelihood of additional assessments or settlements in each of the taxing jurisdictions. At this time, the potential change in unrecognized tax benefits is expected to be immaterial over the next 12 months. The Company believes that its reserves are sufficient to cover any tax, penalties and interest that would result from such examinations.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table presents the calculation of basic and diluted earnings per share ("EPS") (dollars and shares in millions, except per share amounts): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Numerator Net income $ 1,091 $ 771 $ 4,382 $ 342 Preferred stock dividends (30) (15) (69) (31) Net income available to common stockholders 1,061 756 4,313 311 Income allocated to participating securities (6) (5) (24) (2) Net income allocated to common stockholders $ 1,055 $ 751 $ 4,289 $ 309 Denominator Weighted-average shares of common stock outstanding 298 306 303 307 Effect of dilutive common stock equivalents — — — — Weighted-average shares of common stock outstanding and common stock equivalents 298 306 303 307 Basic earnings per common share $ 3.54 $ 2.45 $ 14.17 $ 1.00 Diluted earnings per common share $ 3.54 $ 2.45 $ 14.16 $ 1.00 Anti-dilutive securities were not material and had no impact on the computation of diluted EPS for the three or nine months ended September 30, 2021 and 2020.

Capital Adequacy

Capital Adequacy	9 Months Ended
	Sep. 30, 2021
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Capital Adequacy	Capital Adequacy DFS is subject to the capital adequacy guidelines of the Federal Reserve. Discover Bank, the Company's banking subsidiary, is subject to various regulatory capital requirements as administered by the FDIC. Failure to meet minimum capital requirements can result in the initiation of certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could limit the Company's business activities and have a direct material effect on the financial condition and operating results of DFS and Discover Bank. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, DFS and Discover Bank must meet specific risk-based capital requirements and leverage ratios that involve quantitative measures of assets, liabilities and certain off-balance sheet items, as calculated under regulatory guidelines. Capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings and other factors. DFS and Discover Bank are subject to regulatory and capital rules issued by the Federal Reserve and FDIC, respectively, under the Basel Committee's December 2010 framework ("Basel III rules"). Under the Basel III rules, DFS and Discover Bank are classified as "standardized approach" entities. Standardized approach entities are defined as United States banking organizations with consolidated total assets over $50 billion but not exceeding $250 billion and consolidated total on-balance sheet foreign exposures less than $10 billion. On March 27, 2020, federal bank regulatory agencies announced an interim and now final rule that allows banks that have implemented the CECL accounting model to delay the estimated impact of CECL on regulatory capital for two years, followed by a three-year transition period. For purposes of calculating regulatory capital, the Company has elected to defer recognition of the estimated impact of CECL on regulatory capital for two years in accordance with the final rule; after that period of deferral, the estimated impact of CECL on regulatory capital will be phased in over three years beginning in 2022. Accordingly, the Company's Common Equity Tier 1 ("CET1") capital ratios in 2020 and 2021 are higher than they otherwise would have been. As of September 30, 2021 and December 31, 2020, DFS and Discover Bank met all Basel III minimum capital ratio requirements to which they were subject. DFS and Discover Bank also met the requirements to be considered "well-capitalized" under Regulation Y and prompt corrective action rules, respectively. There have been no conditions or events that management believes have changed DFS' or Discover Bank's category. To be categorized as "well-capitalized," DFS and Discover Bank must maintain minimum capital ratios outlined in the table below. The following table shows the actual capital amounts and ratios of DFS and Discover Bank and comparisons of each to the regulatory minimum and "well-capitalized" requirements (dollars in millions): Actual Minimum Capital Capital Requirements Amount Ratio (1) Amount Ratio Amount (2) Ratio (2) September 30, 2021 Total capital (to risk-weighted assets) Discover Financial Services $ 16,924 18.5 % $ 7,309 ≥8.0% $ 9,136 ≥10.0% Discover Bank $ 15,905 17.7 % $ 7,186 ≥8.0% $ 8,982 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 15,235 16.7 % $ 5,482 ≥6.0% $ 5,482 ≥6.0% Discover Bank $ 13,935 15.5 % $ 5,389 ≥6.0% $ 7,186 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 15,235 13.8 % $ 4,424 ≥4.0% N/A N/A Discover Bank $ 13,935 12.8 % $ 4,353 ≥4.0% $ 5,441 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 14,179 15.5 % $ 4,111 ≥4.5% N/A N/A Discover Bank $ 13,935 15.5 % $ 4,042 ≥4.5% $ 5,839 ≥6.5% December 31, 2020 Total capital (to risk-weighted assets) Discover Financial Services $ 14,711 16.1 % $ 7,298 ≥8.0% $ 9,123 ≥10.0% Discover Bank $ 14,507 16.1 % $ 7,214 ≥8.0% $ 9,018 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 13,006 14.3 % $ 5,474 ≥6.0% $ 5,474 ≥6.0% Discover Bank $ 12,415 13.8 % $ 5,411 ≥6.0% $ 7,214 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 13,006 10.9 % $ 4,757 ≥4.0% N/A N/A Discover Bank $ 12,415 10.5 % $ 4,709 ≥4.0% $ 5,886 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 11,950 13.1 % $ 4,105 ≥4.5% N/A N/A Discover Bank $ 12,415 13.8 % $ 4,058 ≥4.5% $ 5,862 ≥6.5% (1) Capital ratios are calculated based on the Basel III standardized approach rules, subject to applicable transition provisions, including CECL transition provisions. (2) The Basel III rules do not establish well-capitalized thresholds for these measures for bank holding companies. Existing well-capitalized thresholds established in the Federal Reserve's Regulation Y have been included where available.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2021
Commitments Contingencies and Guarantees [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies and Guarantees In the normal course of business, the Company enters into a number of off-balance sheet commitments, transactions and obligations under guarantee arrangements that expose the Company to varying degrees of risk. The Company's commitments, contingencies and guarantee relationships are described below. Commitments Unused Credit Arrangements At September 30, 2021, the Company had unused credit arrangements for loans of approximately $220.1 billion. Such arrangements arise primarily from agreements with customers for unused lines of credit on certain credit cards and certain other loan products, provided there is no violation of conditions in the related agreements. The Company can terminate substantially all of these arrangements at any time and therefore the arrangements do not necessarily represent future cash requirements. The arrangements are periodically reviewed based on account usage, customer creditworthiness and loan qualification. As the Company’s credit card loans are unconditionally cancellable, no liability for expected credit losses is required for unused lines of credit. For all other loans, the Company records a liability for expected credit losses for unfunded commitments, which is presented as part of accrued expenses and other liabilities in the consolidated statements of financial condition. Contingencies See Note 14: Litigation and Regulatory Matters for a description of potential liability arising from pending litigation or regulatory proceedings involving the Company. Guarantees The Company has obligations under certain guarantee arrangements, including contracts, indemnification agreements and representations and warranties, which contingently require the Company to make payments to the guaranteed party based on changes in an underlying asset, liability or equity security of a guaranteed party, rate or index. Also included as guarantees are contracts that contingently require the Company to make payments to a guaranteed party based on another entity's failure to perform under an agreement. The Company's use of guarantees is disclosed below by type of guarantee. Securitizations Representations and Warranties As part of the Company's financing activities, the Company provides representations and warranties that certain assets pledged as collateral in secured borrowing arrangements conform to specified guidelines. The Company performs due diligence intended to ensure that asset guideline qualifications are met. If the assets pledged as collateral do not meet certain conforming guidelines, the Company might be required to replace, repurchase or sell such assets. For example, in its credit card securitization activities, the Company would replace nonconforming receivables by allocating excess seller's interest or from additional transfers from the unrestricted pool of receivables. If the Company could not add enough receivables to satisfy the requirement, an early amortization (or repayment) of investors' interests would be triggered. In its private student loan securitizations, the Company would generally repurchase the loans from the trust at the outstanding principal amount plus interest. The maximum potential amount of future payments the Company could be required to make would be equal to the current outstanding balances of third-party investor interests in credit card asset-backed securities and the principal amount of any private student loan secured borrowings, plus any unpaid interest for the corresponding secured borrowings. The Company has recorded substantially all of the maximum potential amount of future payments in long-term borrowings on the Company's condensed consolidated statements of financial condition. The Company has not recorded any incremental contingent liability associated with its secured borrowing representations and warranties. Management believes that the probability of having to replace, repurchase or sell assets pledged as collateral under secured borrowing arrangements, including an early amortization event, is low. Counterparty Settlement Guarantees Diners Club and DFS Services LLC (on behalf of PULSE) have various counterparty exposures, which are listed below: • Merchant Guarantee . Diners Club has entered into contractual relationships with certain international merchants, which generally include travel-related businesses, for the benefit of all Diners Club licensees. The licensees hold the primary liability to settle the transactions of their customers with these merchants. However, Diners Club retains a counterparty exposure if a licensee fails to meet its financial payment obligation to one of these merchants. • ATM Guarantee. PULSE entered into contractual relationships with certain international ATM acquirers in which DFS Services LLC retains counterparty exposure if an issuer fails to fulfill its settlement obligation. • Global Network Alliance Guarantee . Discover Network, Diners Club and PULSE have entered into contractual relationships with certain international payment networks in which DFS Services LLC retains the counterparty exposure if a network fails to fulfill its settlement obligation. The maximum potential amount of future payments related to such contingent obligations depends on the transaction volume processed between the time a potential counterparty defaults on its settlement and the time the Company disables the settlement of any further transactions for the defaulting party. The Company has some contractual remedies to offset these counterparty settlement exposures (such as letters of credit or pledged deposits). However, there is no limitation on the maximum amount the Company may be liable to pay. The actual amount of the potential exposure cannot be quantified as the Company cannot determine whether particular counterparties will fail to meet their settlement obligations. If all licensees and/or issuers were to become unable to settle their transactions, the Company estimates its maximum potential counterparty exposures to these settlement guarantees would be approximately $80 million as of September 30, 2021. The Company believes that the estimated amounts of maximum potential future payments are not representative of the Company's actual potential loss exposure given Diners Club's and PULSE's insignificant historical losses from these counterparty exposures. As of September 30, 2021, the Company had not recorded any contingent liability in the condensed consolidated financial statements for these counterparty exposures. Management believes that the probability of any payments under these arrangements is low. Discover Network Merchant Chargeback Guarantees The Company operates the Discover Network, issues payment cards and permits third parties to issue payment cards. The Company is contingently liable for certain transactions processed on the Discover Network in the event of a dispute between the payment card customer and a merchant. The contingent liability arises if the disputed transaction involves a merchant or merchant acquirer with whom the Discover Network has a direct relationship. If a dispute is resolved in the customer's favor, the Discover Network will credit or refund the disputed amount to the Discover Network card issuer, which in turn credits its customer's account. The Discover Network will then charge back the disputed amount of the payment card transaction to the merchant or merchant acquirer, where permitted by the applicable agreement, to seek recovery of amounts already paid to the merchant for payment card transactions. If the Discover Network is unable to collect the amount subject to dispute from the merchant or merchant acquirer (e.g., in the event of merchant default or dissolution or after expiration of the period for chargebacks in the applicable agreement), the Discover Network will bear the loss for the amount credited or refunded to the customer. In most instances, a loss by the Discover Network is unlikely to arise in connection with payments on card transactions because most products or services are delivered when purchased and merchants issue credits on returned items in a timely fashion, thus minimizing the likelihood of cardholder disputes with respect to amounts paid by the Discover Network. However, where the product or service is not scheduled to be provided to the customer until a later date following the purchase, the likelihood of a contingent payment obligation by the Discover Network increases. Losses related to merchant chargebacks were not material for the three and nine months ended September 30, 2021 and 2020. The maximum potential amount of obligations of the Discover Network arising from such contingent obligations is estimated to be the portion of the total Discover Network transaction volume processed to date for which timely and valid disputes may be raised under applicable law and relevant issuer and customer agreements. There is no limitation on the maximum amount the Company may be liable to pay to issuers. However, the Company believes that such amount is not representative of the Company's actual potential loss exposure based on the Company's historical experience. The actual amount of the potential exposure cannot be quantified as the Company cannot determine whether the current or cumulative transaction volumes may include or result in disputed transactions. The following table summarizes certain information regarding merchant chargeback guarantees (dollars in millions): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Aggregate sales transaction volume (1) $ 58,107 $ 46,128 $ 160,717 $ 125,214 (1) Represents transactions processed on the Discover Network for which a potential liability exists that, in aggregate, can differ from credit card sales volume. The Company did not record any material contingent liability in the condensed consolidated financial statements for merchant chargeback guarantees as of September 30, 2021 or December 31, 2020.The Company mitigates the risk of potential loss exposure by withholding settlement from merchants, obtaining third-party guarantees, or obtaining escrow deposits or letters of credit from certain merchant acquirers or merchants that are considered a higher risk due to various factors such as time delays in the delivery of products or services. As of September 30, 2021 and December 31, 2020, the Company had escrow deposits and settlement withholdings of $15 million and $16 million, respectively, which are recorded in interest-bearing deposit accounts and accrued expenses and other liabilities on the Company's condensed consolidated statements of financial condition.

Litigation and Regulatory Matte

Litigation and Regulatory Matters	9 Months Ended
	Sep. 30, 2021
Loss Contingency [Abstract]
Litigation and Regulatory Matters	Litigation and Regulatory Matters In the normal course of business, from time to time, the Company has been named as a defendant in various legal actions, including arbitrations, class actions and other litigation, arising in connection with its activities. Certain of the actual or threatened legal actions include claims for substantial compensatory and/or punitive damages or claims for indeterminate amounts of damages. The litigation process is not predictable and can lead to unexpected results. The Company contests liability and/or the amount of damages as appropriate in each pending matter. The Company has historically offered its customers an arbitration clause in its customer agreements. The arbitration clause allows the Company and its customers to quickly and economically resolve disputes. Additionally, the arbitration clause has in some instances limited the costs of, and the Company's exposure to, litigation. Future legal and regulatory challenges and prohibitions may cause the Company to discontinue its offering and use of such clauses. From time to time, the Company is involved in legal actions challenging its arbitration clause. Bills may be periodically introduced in Congress to directly or indirectly prohibit the use of pre-dispute arbitration clauses. The Company is also involved, from time to time, in other reviews, investigations and proceedings (both formal and informal) by governmental agencies regarding the Company's business including, among other matters, consumer regulatory, accounting, tax and other operational matters. The investigations and proceedings may result in significant adverse judgments, settlements, fines, penalties, injunctions, decreases in regulatory ratings, customer restitution or other relief. These outcomes could materially impact the Company's condensed consolidated financial statements, increase its cost of operations, or limit the Company's ability to execute its business strategies and engage in certain business activities. Certain subsidiaries of the Company are subject to a consent order with the Consumer Financial Protection Bureau ("CFPB") regarding certain private student loan servicing practices, as described below. Pursuant to powers granted under federal banking laws, regulatory agencies have broad and sweeping discretion and may assess civil money penalties, require changes to certain business practices or require customer restitution at any time. In accordance with applicable accounting guidance, the Company establishes an accrued liability for legal and regulatory matters when those matters present loss contingencies that are both probable and estimable. Litigation and regulatory settlement-related expenses were $51 million and $54 million for the three and nine months ended September 30, 2021, respectively. Litigation and regulatory settlement-related expenses were immaterial for the three and nine months ended September 30, 2020. There may be an exposure to loss in excess of any amounts accrued. The Company believes the estimate of the aggregate range of reasonably possible losses (meaning the likelihood of losses is more than remote but less than likely), in excess of the amounts that the Company has accrued for legal and regulatory proceedings, is up to $250 million as of September 30, 2021. This estimated range of reasonably possible losses is based on currently available information for those proceedings in which the Company is involved and considers the Company's best estimate of such losses for those matters for which an estimate can be made. It does not represent the Company's maximum potential loss exposure. Various aspects of the proceedings underlying the estimated range will change from time to time and actual results may vary significantly from the estimate. The Company's estimated range noted above involves significant judgment, given the varying stages of the proceedings, the existence of numerous yet to be resolved issues, the breadth of the claims (often spanning multiple years and, in some cases, a wide range of business activities), unspecified damages and/or the novelty of the legal issues presented. The outcome of pending matters could adversely affect the Company's reputation and be material to the Company's condensed consolidated financial condition, operating results and cash flows for a particular future period, depending on, among other things, the level of the Company's income for such period. In July 2015, the Company announced that its subsidiaries, Discover Bank, The Student Loan Corporation and Discover Products Inc. (the "Discover Subsidiaries"), agreed to a consent order with the CFPB with respect to certain private student loan servicing practices (the “2015 Order”). The 2015 Order expired in July 2020. On December 22, 2020, the Discover Subsidiaries agreed to a consent order (the “2020 Order”) with the CFPB resolving the agency’s investigation into Discover Bank’s compliance with the 2015 Order. In connection with the 2020 Order, Discover is required to implement a redress and compliance plan and must pay at least $10 million in consumer redress to consumers who may have been harmed and paid a $25 million civil money penalty to the CFPB. On March 8, 2016, a class-action lawsuit was filed against the Company, other credit card networks, other issuing banks and EMVCo in the United States District Court for the Northern District of California (B&R Supermarket, Inc., d/b/a

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement , provides a three-level hierarchy for classifying fair value measurements of financial instruments based on whether the inputs to the valuation techniques used are observable or unobservable. It also requires certain disclosures about those measurements. The three-level valuation hierarchy is as follows: • Level 1 : Fair values determined by Level 1 inputs are defined as those that utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2 : Fair values determined by Level 2 inputs are those that utilize inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active or inactive markets, quoted prices for the identical assets in an inactive market and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals. The Company evaluates factors such as the frequency of transactions, the size of the bid-ask spread and the significance of adjustments made when considering transactions involving similar assets or liabilities to assess the relevance of those observed prices. If relevant and observable prices are available, the fair values of the related assets or liabilities would be classified as Level 2. • Level 3 : Fair values determined by Level 3 inputs are those based on unobservable inputs and include situations where there is little, if any, market activity for the asset or liability being valued. In instances where the inputs used to measure fair value may fall into different levels of the fair value hierarchy, the level in the fair value hierarchy in which the measurements classified based on the lowest level input that is significant to the fair value measurement in its entirety. Accordingly, the Company may utilize both observable and unobservable inputs in determining the fair values of financial instruments classified within the Level 3 category. The Company evaluates the classification of each fair value measurement within the hierarchy at least quarterly. The Company's assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and involves consideration of factors specific to the asset or liability. Furthermore, certain techniques used to measure fair value involve some degree of judgment and, as a result, are not necessarily indicative of the amounts the Company would realize in a current market exchange. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and liabilities measured at fair value on a recurring basis are as follows (dollars in millions): Quoted Price in Active Markets Significant Significant Total Balance at September 30, 2021 Assets Fair value - OCI United States Treasury and U.S. GSE securities $ 7,571 $ 9 $ — $ 7,580 Residential mortgage-backed securities - Agency — 211 — 211 Available-for-sale investment securities $ 7,571 $ 220 $ — $ 7,791 Fair value - Net income Marketable equity securities $ 600 $ — $ — $ 600 Derivative financial instruments - fair value hedges (1) $ — $ 1 $ — $ 1 Balance at December 31, 2020 Assets Fair value - OCI United States Treasury securities $ 9,354 $ — $ — $ 9,354 Residential mortgage-backed securities - Agency — 300 — 300 Available-for-sale investment securities $ 9,354 $ 300 $ — $ 9,654 Fair value - Net income Derivative financial instruments - fair value hedges (1) $ — $ 1 $ — $ 1 (1) Derivative instrument carrying values in an asset or liability position are presented as part of other assets or accrued expenses and other liabilities, respectively, in the Company's condensed consolidated statements of financial condition. Available-for-Sale Investment Securities Investment securities classified as available-for-sale consist of United States Treasury and U.S. GSE securities and RMBS. The fair value estimates of investment securities classified as Level 1, consisting of United States Treasury securities, are determined based on quoted market prices for the same securities. The Company classifies these U.S. GSE securities and RMBS as Level 2, the fair value estimates of which are based on the best information available. This data may consist of observed market prices for similar securities, broker quotes or discounted cash flow models that incorporate assumptions such as benchmark yields, issuer spreads, prepayment speeds, credit ratings and losses, the priority of which may vary based on the availability of information. The Company validates the fair value estimates provided by pricing services primarily by comparing to valuations obtained through other pricing sources. The Company evaluates pricing variances among different pricing sources to ensure that the valuations utilized are reasonable. The Company also corroborates the reasonableness of the fair value estimates with analysis of trends of significant inputs, such as market interest rate curves. The Company further performs due diligence in understanding the procedures and techniques performed by the pricing services to derive fair value estimates. At September 30, 2021, amounts reported in RMBS reflect U.S. government agency and U.S. GSE obligations issued by Ginnie Mae, Fannie Mae and Freddie Mac with an aggregate par value of $201 million, a weighted-average coupon of 3.24% and a weighted-average remaining maturity of two years. Marketable Equity Securities The Company holds non-controlling equity positions in payment service entities that have actively traded stock and therefore have readily determinable fair values. The Company classifies these equity securities as Level 1, the fair value estimates of which are determined based on quoted share prices for the same securities. Derivative Financial Instruments The Company's derivative financial instruments consist of interest rate swaps and foreign exchange forward contracts. These instruments are classified as Level 2 as their fair values are estimated using proprietary pricing models, containing certain assumptions based on readily observable market-based inputs, including interest rate curves, option volatility and foreign currency forward and spot rates. In determining fair values, the pricing models use widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity and the observable market-based inputs. The fair values of the interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments are based on an expectation of future interest rates derived from the observable market interest rate curves. The Company considers collateral and master netting agreements that mitigate credit exposure to counterparties in determining the counterparty credit risk valuation adjustment. The fair values of the currency instruments are valued by comparing the contracted forward exchange rate pertaining to the specific contract maturities to the current market exchange rate. The Company validates the fair value estimates of interest rate swaps primarily through comparison to the fair value estimates computed by the counterparties to each of the derivative transactions. The Company evaluates pricing variances among different pricing sources to ensure that the valuations utilized are reasonable. The Company also corroborates the reasonableness of the fair value estimates with analysis of trends of significant inputs, such as market interest rate curves. The Company performs due diligence in understanding the impact of any changes to the valuation techniques performed by proprietary pricing models before implementation, working closely with the third-party valuation service and reviewing the service's control objectives at least annually. The Company corroborates the fair value of foreign exchange forward contracts through independent calculation of the fair value estimates. As of October 16, 2020, the Company revised its valuation methodology to reflect changes made by central clearinghouses that changed the discounting methodology and interest calculation of cash variation margin from OIS to the Secured Overnight Financing Rate (“SOFR”) for U.S. Dollar cleared interest rate swaps. The Company's valuation methodology will result in valuations for cleared interest rate swaps that better reflect cleared swap prices obtainable in the markets in which the Company transacts. Pursuant to ASC Topic 848, the Company has elected and applied certain optional expedients and exceptions that provide contract modification and hedge accounting relief to eligible interest rate swaps affected by the change in the discounting methodology. The changes in valuation methodology are applied prospectively as a change in accounting estimate and are immaterial to the Company’s financial statements. Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis The Company also has assets that, under certain conditions, are subject to measurement at fair value on a non-recurring basis. These assets include those associated with acquired businesses, including goodwill and other intangible assets. For these assets, measurement at fair value in periods subsequent to the initial recognition of the assets may be applicable whenever one is tested for impairment. The Company recognized $92 million of impairments related to these assets during the nine months ended September 30, 2021. No impairments were recognized during the three months ended September 30, 2021. See Note 5: Intangible Assets for more information on the impact of the COVID-19 pandemic on intangible assets. Financial Instruments Measured at Other Than Fair Value The following tables disclose the estimated fair value of the Company's financial assets and financial liabilities that are not required to be carried at fair value (dollars in millions): Balance at September 30, 2021 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 227 $ — $ 227 $ 223 Held-to-maturity investment securities $ — $ 227 $ — $ 227 $ 223 Net loan receivables $ — $ — $ 90,019 $ 90,019 $ 82,681 Carrying value approximates fair value (1) Cash and cash equivalents $ 12,716 $ — $ — $ 12,716 $ 12,716 Restricted cash $ 32 $ — $ — $ 32 $ 32 Accrued interest receivables (2) $ — $ 968 $ — $ 968 $ 968 Liabilities Amortized cost Time deposits (3) $ — $ 22,300 $ — $ 22,300 $ 21,831 Long-term borrowings - owed to securitization investors $ — $ 9,014 $ 110 $ 9,124 $ 9,064 Other long-term borrowings — 10,204 — 10,204 9,452 Long-term borrowings $ — $ 19,218 $ 110 $ 19,328 $ 18,516 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 124 $ — $ 124 $ 124 Balance at December 31, 2020 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 269 $ — $ 269 $ 260 Held-to-maturity investment securities $ — $ 269 $ — $ 269 $ 260 Net loan receivables $ — $ — $ 91,200 $ 91,200 $ 82,223 Carrying value approximates fair value (1) Cash and cash equivalents $ 13,564 $ — $ — $ 13,564 $ 13,564 Restricted cash $ 25 $ — $ — $ 25 $ 25 Other short-term investments $ 2,200 $ — $ — $ 2,200 $ 2,200 Accrued interest receivables (2) $ — $ 992 $ — $ 992 $ 992 Liabilities Amortized cost Time deposits (3) $ — $ 29,090 $ — $ 29,090 $ 28,269 Long-term borrowings - owed to securitization investors $ — $ 10,794 $ 130 $ 10,924 $ 10,840 Other long-term borrowings — 11,418 — 11,418 10,401 Long-term borrowings $ — $ 22,212 $ 130 $ 22,342 $ 21,241 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 233 $ — $ 233 $ 233 (1) The carrying values of these assets and liabilities approximate fair value due to their short-term nature. (2) Accrued interest receivable and payable carrying values are presented as part of other assets or accrued expenses and other liabilities, respectively, in the Company's condensed consolidated statements of financial condition. (3) Excludes deposits without contractually defined maturities for all periods presented.

Derivatives and Hedging Activit

Derivatives and Hedging Activities	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	Derivatives and Hedging Activities The Company uses derivatives to manage its exposure to various financial risks. The Company does not enter into derivatives for trading or speculative purposes. Certain derivatives used to manage the Company's exposure to foreign currency are not designated as hedges and do not qualify for hedge accounting. Derivatives may give rise to counterparty credit risk, which generally is addressed through collateral arrangements as described under the sub-heading "— Collateral Requirements and Credit-Risk Related Contingency Features." The Company enters into derivative transactions with established dealers that meet minimum credit criteria established by the Company. All counterparties must be pre-approved before engaging in any transaction with the Company. The Company regularly monitors counterparties to ensure compliance with the Company's risk policies and limits. In determining the counterparty credit risk valuation adjustment for the fair values of derivatives, if any, the Company considers collateral and legally enforceable master netting agreements that mitigate credit exposure to related counterparties. All derivatives are recorded in other assets at their gross positive fair values and in accrued expenses and other liabilities at their gross negative fair values. See Note 15: Fair Value Measurements for a description of the valuation methodologies used for derivatives. Cash collateral amounts associated with derivative positions that are cleared through an exchange are legally characterized as settlement of the derivative positions. Such collateral amounts are reflected as offsets to the associated derivatives balances recorded in other assets or in accrued expenses and other liabilities. Other cash collateral posted and held balances are recorded in other assets and deposits, respectively, in the condensed consolidated statements of financial condition. Collateral amounts recorded in the condensed consolidated statements of financial condition are based on the net collateral posted or held position for each applicable legal entity's master netting arrangement with each counterparty. Derivatives Designated as Hedges Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows arising from changes in interest rates, or other types of forecasted transactions, are considered cash flow hedges. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Cash Flow Hedges The Company uses interest rate swaps to manage its exposure to changes in interest rates related to future cash flows resulting from interest received on interest-earning assets and interest payments on funding instruments. These interest rate swaps qualify for hedge accounting in accordance with ASC Topic 815, Derivatives and Hedging ("ASC 815"). As of September 30, 2021 and December 31, 2020, the Company's outstanding cash flow hedges related only to interest receipts from credit card receivables and had an initial maximum period of two years. The change in the fair value of derivatives designated as cash flow hedges is recorded in OCI and is subsequently reclassified into earnings in the period that the hedged forecasted cash flows affect earnings. Amounts reported in AOCI related to derivatives at September 30, 2021, will be reclassified to interest income as interest receipts are accrued on the Company's then outstanding credit card receivables. During the next 12 months, the Company estimates it will reclassify $3 million of pretax earnings primarily related to one terminated derivative formerly designated as a cash flow hedge. Fair Value Hedges The Company is exposed to changes in the fair value of its fixed-rate debt obligations due to changes in interest rates. The Company uses interest rate swaps to manage its exposure to changes in fair value of certain fixed-rate long-term borrowings, including securitized debt and bank notes, attributable to changes in LIBOR or OIS rate, which are benchmark interest rates defined by ASC 815. These interest rate swaps qualify as fair value hedges in accordance with ASC 815. Changes in both (i) the fair values of the derivatives and (ii) the hedged long-term borrowings relating to the risk being hedged are recorded in interest expense. The changes generally provide substantial offset to one another, with any difference recognized in interest expense. Derivatives Not Designated as Hedges Foreign Exchange Forward Contracts The Company has foreign exchange forward contracts that are economic hedges and are not designated as accounting hedges. The Company enters into foreign exchange forward contracts to manage foreign currency risk. Changes in the fair value of these contracts are recorded in other income. Derivatives Cleared Through an Exchange Cash variation margin payments on derivatives cleared through an exchange are legally considered settlement payments and are accounted for with corresponding derivative positions as one unit of account and not presented separately as collateral. With settlement payments on derivative positions cleared through this exchange reflected as offsets to the associated derivative asset and liability balances, the fair values of derivative instruments and collateral balances shown are generally reduced. Derivatives Activity The following table summarizes the fair value (including accrued interest) and outstanding notional amounts of derivative instruments and related collateral balances (dollars in millions): September 30, 2021 December 31, 2020 Notional Number of Outstanding Derivative Contracts Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities Derivatives designated as hedges Interest rate swaps—cash flow hedge $ 250 1 $ — $ — $ 250 $ — $ — Interest rate swaps—fair value hedge $ 8,275 10 1 — $ 11,625 1 — Derivatives not designated as hedges Foreign exchange forward contracts (1) $ 26 6 — — $ 24 — — Interest rate swaps $ 5 1 — — $ — — — Total gross derivative assets/liabilities (2) 1 — 1 — Less: collateral held/posted (3) — — — — Total net derivative assets/liabilities $ 1 $ — $ 1 $ — (1) The foreign exchange forward contracts have notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 788 million as of September 30, 2021, and notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 596 million as of December 31, 2020. (2) In addition to the derivatives disclosed in the table, the Company enters into forward contracts to purchase when-issued mortgage-backed securities as part of its community reinvestment initiatives. At September 30, 2021, the Company had no outstanding contracts. At December 31, 2020, the Company had one outstanding contract with a total notional amount of $27 million and an immaterial fair value. (3) Collateral amounts, which consist of cash and investment securities, are limited to the related derivative asset/liability balance and do not include excess collateral received/pledged. The following amounts were recorded on the statements of financial condition related to cumulative basis adjustments for fair value hedges (dollars in millions): September 30, 2021 December 31, 2020 Carrying Amount of Hedged Liability Cumulative Amount of Fair Value Hedging Adjustment Increasing the Carrying Amount of Hedged Liability Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increasing the Carrying Amount of Hedged Liability Long-term borrowings $ 8,885 $ 115 $ 11,881 $ 281 The following table summarizes the impact of the derivative instruments on income and indicates where within the condensed consolidated financial statements such impact is reported (dollars in millions): Location and Amount of (Losses) Gains Recognized on the Condensed Consolidated Statements of Income Interest Expense Deposits Long-Term Borrowings Other Income For the Three Months Ended September 30, 2021 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (156) $ (113) $ 18 The effects of cash flow and fair value hedging Gains (losses) on cash flow hedging relationship Amounts reclassified from OCI into earnings $ — $ — $ — Gains on fair value hedging relationships Gains on hedged items $ — $ 45 $ — Gains (losses) on interest rate swaps — (9) — Total gains on fair value hedging relationships $ — $ 36 $ — For the Three Months Ended September 30, 2020 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (287) $ (126) $ 17 The effects of cash flow and fair value hedging Gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (4) $ — $ — Gains on fair value hedging relationships Gains on hedged items $ — $ 59 $ — Gains (losses) on interest rate swaps — (9) — Total gains on fair value hedging relationships $ — $ 50 $ — The effects of derivatives not designated in hedging relationships Gains (losses) on derivatives not designated as hedges $ — $ — $ (1) Location and Amount of (Losses) Gains Recognized on the Condensed Consolidated Statements of Income Interest Expense Deposits Long-Term Borrowings Other Income For the Nine Months Ended September 30, 2021 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (519) $ (356) $ 47 The effects of cash flow and fair value hedging Gains (losses) on cash flow hedging relationship Amounts reclassified from OCI into earnings $ — $ (2) $ — Gains on fair value hedging relationships Gains on hedged items $ — $ 167 $ — Gains (losses) on interest rate swaps — (38) — Total gains on fair value hedging relationships $ — $ 129 $ — For the Nine Months Ended September 30, 2020 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (1,000) $ (479) $ 59 The effects of cash flow and fair value hedging Losses on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (9) $ (2) $ — Gains on fair value hedging relationship Gains (losses) on hedged items $ — $ (326) $ — Gains on interest rate swaps — 434 — Total gains on fair value hedging relationships $ — $ 108 $ — For the impact of the derivative instruments on OCI, see Note 9: Accumulated Other Comprehensive Income. Collateral Requirements and Credit-Risk Related Contingency Features The Company has master netting arrangements and minimum collateral posting thresholds with its counterparties for its fair value and cash flow hedge interest rate swaps and foreign exchange forward contracts. The Company has not sought a legal opinion in relation to the enforceability of its master netting arrangements and, as such, does not report any of these positions on a net basis. Collateral is required by either the Company or its subsidiaries or the counterparty depending on the net fair value position of the derivatives held with that counterparty. These collateral receivable or payable amounts are generally not offset against the fair value of these derivatives but are recorded separately in other assets or deposits. Most of the Company's cash collateral amounts relate to positions cleared through an exchange and are reflected as offsets to the associated derivatives balances recorded in other assets and accrued expenses and other liabilities. The Company also has agreements with certain of its derivative counterparties that contain a provision under which the Company could be declared in default on any of its derivative obligations if the Company defaults on any of its indebtedness, including default where the lender has not accelerated repayment of the indebtedness.

Segment Disclosures

Segment Disclosures	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Segment Disclosures	Segment Disclosures The Company manages its business activities in two segments: Digital Banking and Payment Services. • Digital Banking: The Digital Banking segment includes Discover-branded credit cards issued to individuals on the Discover Network and other consumer products and services, including private student loans, personal loans, home loans and other consumer lending and deposit products. The majority of Digital Banking revenues relate to interest income earned on the segment's loan products. Additionally, the Company's credit card products generate substantially all revenues related to discount and interchange, protection products and loan fee income. • Payment Services: The Payment Services segment includes PULSE, an automated teller machine, debit and electronic funds transfer network; Diners Club, a global payments network; and the Company's Network Partners business, which provides payment transaction processing and settlement services on the Discover Network. The majority of Payment Services revenues relate to transaction processing revenue from PULSE and royalty and licensee revenue from Diners Club. The business segment reporting provided to and used by the Company's chief operating decision-maker is prepared using the following principles and allocation conventions: • The Company aggregates operating segments when determining reportable segments. • Corporate overhead is not allocated between segments; all corporate overhead is included in the Digital Banking segment. • Through its operation of the Discover Network, the Digital Banking segment incurs fixed marketing, servicing and infrastructure costs that are not specifically allocated among the segments, except for an allocation of direct and incremental costs driven by the Company's Payment Services segment. • The Company's assets are not allocated among the operating segments in the information reviewed by the Company's chief operating decision-maker. • The revenues of each segment are derived from external sources. The segments do not earn revenue from intercompany sources. • Income taxes are not specifically allocated between the operating segments in the information reviewed by the Company's chief operating decision-maker. The following table presents segment data (dollars in millions): Digital Payment Total For the Three Months Ended September 30, 2021 Interest income Credit card loans $ 2,193 $ — $ 2,193 Private student loans 184 — 184 Personal loans 219 — 219 Other loans 30 — 30 Other interest income 48 — 48 Total interest income 2,674 — 2,674 Interest expense 269 — 269 Net interest income 2,405 — 2,405 Provision for credit losses 185 — 185 Other income (loss) 447 (75) 372 Other expense 1,151 39 1,190 Income (loss) before income taxes $ 1,516 $ (114) $ 1,402 For the Three Months Ended September 30, 2020 Interest income Credit card loans $ 2,171 $ — $ 2,171 Private student loans 182 — 182 Personal loans 237 — 237 Other loans 27 — 27 Other interest income 64 — 64 Total interest income 2,681 — 2,681 Interest expense 416 — 416 Net interest income 2,265 — 2,265 Provision for credit losses 750 — 750 Other income 371 78 449 Other expense 969 36 1,005 Income before income taxes $ 917 $ 42 $ 959 Digital Payment Total For the Nine Months Ended September 30, 2021 Interest income Credit card loans $ 6,452 $ — $ 6,452 Private student loans 554 — 554 Personal loans 662 — 662 Other loans 85 — 85 Other interest income 156 — 156 Total interest income 7,909 — 7,909 Interest expense 875 — 875 Net interest income 7,034 — 7,034 Provision for credit losses (45) — (45) Other income 1,284 833 2,117 Other expense 3,290 203 3,493 Income before income tax expense $ 5,073 $ 630 $ 5,703 For the Nine Months Ended September 30, 2020 Interest income Credit card loans $ 6,760 $ — $ 6,760 Private student loans 569 — 569 Personal loans 722 — 722 Other loans 78 — 78 Other interest income 206 — 206 Total interest income 8,335 — 8,335 Interest expense 1,482 — 1,482 Net interest income 6,853 — 6,853 Provision for credit losses 4,603 — 4,603 Other income 1,091 320 1,411 Other expense 3,069 172 3,241 Income before income tax expense $ 272 $ 148 $ 420

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers ASC Topic 606, Revenue from Contracts with Customers ("ASC 606"), generally applies to the sales of any good or service for which no other specific accounting guidance is provided. ASC 606 defines a principles-based model under which revenue from a contract is allocated to the distinct performance obligations within the contract and recognized in income as each performance obligation is satisfied. The Company's revenue that is subject to this model includes discount and interchange, protection products fees, transaction processing revenue and certain amounts classified as other income. The following table presents revenue from contracts with customers disaggregated by business segment and reconciles revenue from contracts with customers to total other income (dollars in millions): Digital Banking Payment Services Total For the Three Months Ended September 30, 2021 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 280 $ 19 $ 299 Protection products revenue 43 — 43 Transaction processing revenue — 58 58 Other income 3 15 18 Total other income subject to ASC 606 (2) 326 92 418 Other income not subject to ASC 606 Loan fee income 121 — 121 Unrealized gains (losses) on equity investments — (167) (167) Total other income (loss) not subject to ASC 606 121 (167) (46) Total other income (loss) by operating segment $ 447 $ (75) $ 372 For the Three Months Ended September 30, 2020 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 225 $ 13 $ 238 Protection products revenue 44 — 44 Transaction processing revenue — 50 50 Other income 2 15 17 Total other income subject to ASC 606 (2) 271 78 349 Other income not subject to ASC 606 Loan fee income 100 — 100 Total other income not subject to ASC 606 100 — 100 Total other income by operating segment $ 371 $ 78 $ 449 Digital Banking Payment Services Total For the Nine Months Ended September 30, 2021 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 826 $ 53 $ 879 Protection products revenue 129 — 129 Transaction processing revenue — 167 167 Other (loss) income (4) 51 47 Total other income subject to ASC 606 (2) 951 271 1,222 Other income not subject to ASC 606 Loan fee income 333 — 333 Unrealized gains on equity investments — 562 562 Total other income not subject to ASC 606 333 562 895 Total other income by operating segment $ 1,284 $ 833 $ 2,117 For the Nine Months Ended September 30, 2020 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 644 $ 47 $ 691 Protection products revenue 135 — 135 Transaction processing revenue — 143 143 Other income 8 51 59 Total other income subject to ASC 606 (2) 787 241 1,028 Other income not subject to ASC 606 Loan fee income 304 — 304 Realized gains on equity investments — 79 79 Total other income not subject to ASC 606 304 79 383 Total other income by operating segment $ 1,091 $ 320 $ 1,411 (1) Net of rewards, including Cashback Bonus rewards, of $689 million and $514 million for the three months ended September 30, 2021 and 2020, respectively, and $1.8 billion and $1.4 billion for the nine months ended September 30, 2021 and 2020, respectively. (2) Excludes deposit product fees that are reported within net interest income, which were immaterial for the three and nine months ended September 30, 2021 and 2020. For a detailed description of the Company's significant revenue recognition accounting policies, see Note 2: Summary of Significant Accounting Policies to the consolidated financial statements in the Company's annual report on Form 10-K for the year ended December 31, 2020.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company has evaluated events and transactions that have occurred subsequent to September 30, 2021, and determined that there were no subsequent events that would require recognition or disclosure in the condensed consolidated financial statements.

Background and Basis of Prese_2

Background and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP") for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, the financial statements reflect all adjustments necessary for the fair presentation of results for the interim period. All such adjustments are of a normal, recurring nature.
Use of estimates	The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and related disclosures. These estimates are based on information available as of the date of the condensed consolidated financial statements. The Company believes that the estimates used in the preparation of the condensed consolidated financial statements are reasonable. Actual results could differ from these estimates.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Schedule of Investment Securities	The Company's other short-term investments and investment securities consist of the following (dollars in millions): September 30, December 31, United States Treasury bills (1) $ — $ 2,200 Total other short-term investments $ — $ 2,200 United States Treasury (2) and U.S. GSE (3) securities $ 7,580 $ 9,354 Residential mortgage-backed securities - Agency (3) 434 560 Total investment securities $ 8,014 $ 9,914 (1) Includes United States Treasury bills with maturity dates greater than 90 days but less than one year at the time of acquisition. (2) Includes $56 million and $117 million of United States Treasury securities pledged as swap collateral as of September 30, 2021 and December 31, 2020, respectively. (3) Consists of securities issued by Fannie Mae, Freddie Mac, Ginnie Mae, or the Federal Home Loan Bank.
Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value	The amortized cost, gross unrealized gains and losses and fair value of available-for-sale and held-to-maturity investment securities are as follows (dollars in millions): Amortized Gross Gross Fair Value At September 30, 2021 Available-for-Sale Investment Securities (1) United States Treasury and U.S. GSE securities $ 7,362 $ 218 $ — $ 7,580 Residential mortgage-backed securities - Agency 204 7 — 211 Total available-for-sale investment securities $ 7,566 $ 225 $ — $ 7,791 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 223 $ 5 $ (1) $ 227 Total held-to-maturity investment securities $ 223 $ 5 $ (1) $ 227 At December 31, 2020 Available-for-Sale Investment Securities (1) United States Treasury securities $ 8,987 $ 367 $ — $ 9,354 Residential mortgage-backed securities - Agency 290 10 — 300 Total available-for-sale investment securities $ 9,277 $ 377 $ — $ 9,654 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 260 $ 9 $ — $ 269 Total held-to-maturity investment securities $ 260 $ 9 $ — $ 269 (1) Available-for-sale investment securities are reported at fair value. (2) Held-to-maturity investment securities are reported at amortized cost. (3) Amounts represent residential mortgage-backed securities ("RMBS") that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.
Schedule of Maturities of Available-for-Sale Debt Securities and Held-to-Maturity Debt Securities	Maturities of available-for-sale debt securities and held-to-maturity debt securities are provided in the following table (dollars in millions): At September 30, 2021 One Year After One After Five After Ten Total Available-for-Sale Investment Securities—Amortized Cost United States Treasury and U.S. GSE securities $ 2,616 $ 4,737 $ 9 $ — $ 7,362 Residential mortgage-backed securities - Agency (1) 2 21 174 7 204 Total available-for-sale investment securities $ 2,618 $ 4,758 $ 183 $ 7 $ 7,566 Held-to-Maturity Investment Securities—Amortized Cost Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 223 $ 223 Total held-to-maturity investment securities $ — $ — $ — $ 223 $ 223 Available-for-Sale Investment Securities—Fair Values United States Treasury and U.S. GSE securities $ 2,641 $ 4,931 $ 8 $ — $ 7,580 Residential mortgage-backed securities - Agency (1) 2 21 180 8 211 Total available-for-sale investment securities $ 2,643 $ 4,952 $ 188 $ 8 $ 7,791 Held-to-Maturity Investment Securities—Fair Values Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 227 $ 227 Total held-to-maturity investment securities $ — $ — $ — $ 227 $ 227 (1) Maturities of RMBS are reflective of the contractual maturities of the investment.

Loan Receivables (Tables)

Loan Receivables (Tables)	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Schedule of Loan Receivables	The Company's classes of receivables within the two portfolio segments are depicted in the following table (dollars in millions): September 30, December 31, Credit card loans (1)(2) $ 70,320 $ 71,472 Other loans (3) Private student loans (4) 10,184 9,954 Personal loans 6,890 7,177 Other loans 2,148 1,846 Total other loans 19,222 18,977 Total loan receivables 89,542 90,449 Allowance for credit losses (6,861) (8,226) Net loan receivables $ 82,681 $ 82,223 (1) Amounts include carrying values of $12.9 billion and $16.7 billion underlying investors' interest in trust debt at September 30, 2021 and December 31, 2020, respectively, and $11.6 billion and $10.6 billion in seller's interest at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information. (2) Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $379 million and $420 million at September 30, 2021 and December 31, 2020, respectively. (3) Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $503 million, $41 million and $6 million, respectively, at September 30, 2021 and $469 million, $49 million and $6 million, respectively, at December 31, 2020. (4) Amounts include carrying values of $215 million and $250 million in loans pledged as collateral against the notes issued from a private student loan securitization trust at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
Schedule of Credit Risk Profile by FICO Score and Origination Year	The following table provides the distribution of the amortized cost basis (excluding accrued interest receivable presented in other assets) by the most recent FICO scores available for the Company's customers for credit card, private student and personal loan receivables (dollars in millions): Credit Risk Profile by FICO Score September 30, 2021 December 31, 2020 660 and Above Less than 660 660 and Above Less than 660 $ % $ % $ % $ % Credit card loans (1) $ 59,005 84 % $ 11,315 16 % $ 58,950 82 % $ 12,522 18 % Private student loans by origination year (2)(3) 2021 $ 1,011 94 % $ 70 6 % 2020 1,593 97 % 54 3 % $ 1,173 95 % $ 60 5 % 2019 1,485 96 % 56 4 % 1,659 96 % 61 4 % 2018 1,185 95 % 58 5 % 1,365 96 % 61 4 % 2017 898 95 % 52 5 % 1,052 95 % 57 5 % Prior 3,521 95 % 201 5 % 4,219 94 % 247 6 % Total private student loans $ 9,693 95 % $ 491 5 % $ 9,468 95 % $ 486 5 % Personal loans by origination year 2021 $ 2,541 99 % $ 18 1 % 2020 1,921 98 % 37 2 % $ 2,880 99 % $ 25 1 % 2019 1,291 95 % 66 5 % 2,183 96 % 90 4 % 2018 550 92 % 51 8 % 1,018 92 % 90 8 % 2017 276 88 % 36 12 % 558 89 % 69 11 % Prior 87 84 % 16 16 % 227 86 % 37 14 % Total personal loans $ 6,666 97 % $ 224 3 % $ 6,866 96 % $ 311 4 % (1) Amounts include $881 million and $1.0 billion of revolving line-of-credit arrangements that were converted to term loans as a result of a troubled debt restructuring ("TDR") program as of September 30, 2021 and December 31, 2020, respectively. (2) A majority of private student loan originations occur in the third quarter and disbursements can span multiple calendar years. (3) FICO score represents the higher credit score of the cosigner or borrower.
Schedule of Delinquent Loans by Origination Year	The amortized cost basis (excluding accrued interest receivable presented in other assets) of delinquent loans in the Company's loan portfolio is shown below for credit card, private student and personal loan receivables (dollars in millions): September 30, 2021 December 31, 2020 30-89 Days 90 or Total Past 30-89 Days 90 or Total Past Credit card loans $ 573 $ 467 $ 1,040 $ 739 $ 739 $ 1,478 Private student loans by origination year (1) 2021 $ — $ — $ — 2020 4 1 5 $ — $ — $ — 2019 11 2 13 3 1 4 2018 14 4 18 9 3 12 2017 15 5 20 12 4 16 Prior 78 24 102 86 20 106 Total private student loans $ 122 $ 36 $ 158 $ 110 $ 28 $ 138 Personal loans by origination year 2021 $ 2 $ — $ 2 2020 7 2 9 $ 5 $ 2 $ 7 2019 12 5 17 18 9 27 2018 8 3 11 15 7 22 2017 5 2 7 10 5 15 Prior 2 1 3 5 2 7 Total personal loans $ 36 $ 13 $ 49 $ 53 $ 25 $ 78 (1) Private student loans may include a deferment period, during which customers are not required to make payments while enrolled in school at least half time as determined by the school. During a deferment period, these loans do not advance into delinquency.
Schedule of Changes in the Allowance for Credit Losses	The following tables provide changes in the Company's allowance for credit losses (dollars in millions): For the Three Months Ended September 30, 2021 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at June 30, 2021 $ 5,409 $ 828 $ 745 $ 44 $ 7,026 Additions Provision for credit losses (1) 178 46 (64) — 160 Deductions Charge-offs (495) (23) (38) — (556) Recoveries 206 6 19 — 231 Net charge-offs (289) (17) (19) — (325) Balance at September 30, 2021 $ 5,298 $ 857 $ 662 $ 44 $ 6,861 For the Three Months Ended September 30, 2020 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at June 30, 2020 $ 6,491 $ 799 $ 857 $ 37 $ 8,184 Additions Provision for credit losses (1) 604 55 49 2 710 Deductions Charge-offs (759) (20) (62) (1) (842) Recoveries 155 6 13 — 174 Net charge-offs (604) (14) (49) (1) (668) Balance at September 30, 2020 $ 6,491 $ 840 $ 857 $ 38 $ 8,226 For the Nine Months Ended September 30, 2021 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at December 31, 2020 $ 6,491 $ 840 $ 857 $ 38 $ 8,226 Additions Provision for credit losses (1) (18) 61 (96) 6 (47) Deductions Charge-offs (1,778) (63) (150) — (1,991) Recoveries 603 19 51 — 673 Net charge-offs (1,175) (44) (99) — (1,318) Balance at September 30, 2021 $ 5,298 $ 857 $ 662 $ 44 $ 6,861 For the Nine Months Ended September 30, 2020 Credit Card Loans Private Student Loans Personal Loans Other Loans Total Loans Balance at December 31, 2019 (2) $ 2,883 $ 148 $ 348 $ 4 $ 3,383 Cumulative effect of ASU No. 2016-13 adoption (3) 1,667 505 265 24 2,461 Balance at January 1, 2020 4,550 653 613 28 5,844 Additions Provision for credit losses (1) 3,916 233 426 11 4,586 Deductions Charge-offs (2,480) (62) (224) (1) (2,767) Recoveries 505 16 42 — 563 Net charge-offs (1,975) (46) (182) (1) (2,204) Balance at September 30, 2020 $ 6,491 $ 840 $ 857 $ 38 $ 8,226 (1) Excludes a $25 million and $40 million reclassification of the liability for expected credit losses on unfunded commitments for the three months ended September 30, 2021 and 2020, respectively, and $2 million and $17 million for the nine months ended September 30, 2021 and 2020, respectively, as the liability is recorded in accrued expenses and other liabilities in the Company's condensed consolidated statements of financial condition. (2) Prior to the adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. (3) Represents the adjustment to the allowance for credit losses due to the adoption of ASU No. 2016-13 on January 1, 2020.
Schedule of Net Charge-offs of Interest and Fee Revenues on Loan Receivables	Net charge-offs of principal are recorded against the allowance for credit losses, as shown in the preceding table. Information regarding net charge-offs of interest and fee revenues on credit card and other loans is as follows (dollars in millions): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Interest and fees accrued subsequently charged-off, net of recoveries (recorded as a reduction of interest income) $ 57 $ 114 $ 232 $ 393 Fees accrued subsequently charged-off, net of recoveries (recorded as a reduction to other income) $ 15 $ 27 $ 59 $ 95
Schedule of Delinquent and Non-Accruing Loans	The amortized cost basis (excluding accrued interest receivable presented in other assets) of delinquent and non-accruing loans in the Company's loan portfolio is shown below for each class of loan receivables (dollars in millions): 30-89 Days 90 or Total Past 90 or Total Non-accruing (1) At September 30, 2021 Credit card loans $ 573 $ 467 $ 1,040 $ 430 $ 201 Other loans Private student loans 122 36 158 35 8 Personal loans 36 13 49 12 9 Other loans 5 6 11 2 14 Total other loans 163 55 218 49 31 Total loan receivables $ 736 $ 522 $ 1,258 $ 479 $ 232 At December 31, 2020 Credit card loans $ 739 $ 739 $ 1,478 $ 687 $ 209 Other loans Private student loans 110 28 138 27 12 Personal loans 53 25 78 23 12 Other loans 8 3 11 — 10 Total other loans 171 56 227 50 34 Total loan receivables $ 910 $ 795 $ 1,705 $ 737 $ 243 (1) The Company estimates that the gross interest income that would have been recorded under the original terms of non-accruing credit card loans was $6 million and $7 million for the three months ended September 30, 2021 and 2020, respectively, and $21 million and $25 million for the nine months ended September 30, 2021 and 2020, respectively. The Company does not separately track the amount of gross interest income that would have been recorded under the original terms of loans. Instead, the Company estimated this amount based on customers' current balances and most recent interest rates.
Schedule of Loans That Entered a Modification Program During the Period	The following table provides information on loans that entered a TDR program during the period (dollars in millions): For the Three Months Ended September 30, 2021 2020 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 13,964 $ 86 20,779 $ 150 Private student loans 102 $ 2 118 $ 2 Personal loans 888 $ 10 2,505 $ 33 For the Nine Months Ended September 30, 2021 2020 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 48,887 $ 315 130,869 $ 875 Private student loans 355 $ 7 1,767 $ 32 Personal loans 3,102 $ 38 6,315 $ 83 (1) Accounts that entered a credit card TDR program include $72 million and $143 million that were converted from revolving line-of-credit arrangements to term loans during the three months ended September 30, 2021 and 2020, respectively, and $288 million and $529 million for the nine months ended September 30, 2021 and 2020, respectively.
Schedule of Troubled Debt Restructurings That Subsequently Defaulted	The following table presents the carrying value of loans that experienced a default during the period that had been modified in a TDR during the 15 months preceding the end of each period (dollars in millions): For the Three Months Ended September 30, 2021 2020 Number of Accounts Aggregated Outstanding Balances Upon Default Number of Accounts Aggregated Outstanding Balances Upon Default TDRs that subsequently defaulted Credit card loans (1)(2) 3,679 $ 21 8,983 $ 52 Private student loans (3) 83 $ 2 272 $ 6 Personal loans (2) 399 $ 6 624 $ 9 For the Nine Months Ended September 30, 2021 2020 Number of Accounts Aggregated Outstanding Balances Upon Default Number of Accounts Aggregated Outstanding Balances Upon Default TDRs that subsequently defaulted Credit card loans (1)(2) 14,205 $ 84 41,285 $ 235 Private student loans (3) 214 $ 5 876 $ 18 Personal loans (2) 1,287 $ 18 2,446 $ 36 (1) For credit card loans that default from a temporary program, accounts revert to the pre-modification terms and charging privileges remain suspended in most cases. (2) For credit card loans and personal loans, a customer defaults from a loan modification program after either two consecutive missed payments or at charge-off, depending on the program. The outstanding balance upon default is generally the loan balance at the end of the month prior to default.

Credit Card and Private Stude_2

Credit Card and Private Student Loan Securitization Activities (Tables)	9 Months Ended
	Sep. 30, 2021
Variable Interest Entities Disclosure [Abstract]
Schedule of Restricted Credit Card Securitized Assets	The carrying values of these restricted assets, which are presented on the Company's condensed consolidated statements of financial condition as relating to securitization activities, are shown in the following table (dollars in millions): September 30, December 31, Restricted cash $ 23 $ 16 Investors' interests held by third-party investors 8,925 10,600 Investors' interests held by wholly-owned subsidiaries of Discover Bank 3,971 6,121 Seller's interest 11,640 10,575 Loan receivables (1) 24,536 27,296 Allowance for credit losses allocated to securitized loan receivables (1) (1,436) (1,936) Net loan receivables 23,100 25,360 Other 3 3 Carrying value of assets of consolidated variable interest entities $ 23,126 $ 25,379 (1) The Company maintains its allowance for credit losses at an amount equal to lifetime expected credit losses associated with all loan receivables, which includes all loan receivables in the trusts. Therefore, the credit risk associated with the transferred receivables is fully reflected on the Company's statements of financial condition in accordance with GAAP.
Schedule of Restricted Private Student Loan Securitized Assets	The carrying values of these restricted assets, which are presented on the Company's condensed consolidated statements of financial condition as relating to securitization activities, are shown in the following table (dollars in millions): September 30, December 31, Restricted cash $ 9 $ 9 Private student loan receivables 215 250 Carrying value of assets of consolidated variable interest entities $ 224 $ 259

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2021
Deposits [Abstract]
Schedule of Interest Bearing Deposit Accounts	The following table provides a summary of interest-bearing deposit accounts (dollars in millions): September 30, December 31, Certificates of deposit in amounts less than $100,000 $ 14,592 $ 19,105 Certificates of deposit in amounts $100,000 or greater (1) 7,239 9,164 Savings deposits, including money market deposit accounts 49,295 47,426 Total interest-bearing deposits $ 71,126 $ 75,695 (1) Includes $2.0 billion and $2.6 billion in certificates of deposit equal to or greater than $250,000, the Federal Deposit Insurance Corporation ("FDIC") insurance limit, as of September 30, 2021 and December 31, 2020, respectively.
Schedule of $100,000 or More Certificates of Deposit Maturities	The following table summarizes certificates of deposit in amounts of $100,000 or greater by contractual maturity (dollars in millions): September 30, Three months or less $ 1,458 Over three months through six months 1,640 Over six months through twelve months 2,711 Over twelve months 1,430 Total $ 7,239
Schedule of Certificates of Deposit Maturities	The following table summarizes certificates of deposit maturing over the remainder of this year, over each of the next four years and thereafter (dollars in millions): September 30, 2021 $ 4,171 2022 11,133 2023 2,663 2024 1,451 2025 870 Thereafter 1,543 Total $ 21,831

Long-Term Borrowings (Tables)

Long-Term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-Term Borrowings and Weighted Average Interest Rates	Long-term borrowings consist of borrowings having original maturities of one year or more. The following table provides a summary of the Company's long-term borrowings and weighted-average interest rates on outstanding balances (dollars in millions): September 30, 2021 December 31, 2020 Maturity Interest Weighted-Average Interest Rate Outstanding Amount Outstanding Amount Securitized Debt Fixed-rate asset-backed securities (1) 2022-2026 0.58% - 3.04% 2.01% $ 5,607 $ 6,041 Floating-rate asset-backed securities (2) 2022-2024 0.41% - 0.68% 0.54% 3,347 4,669 Total Discover Card Master Trust I and Discover Card Execution Note Trust 8,954 10,710 Floating-rate asset-backed security (3)(4) 2031 4.25% 4.25% 110 130 Total private student loan securitization trust 110 130 Total long-term borrowings - owed to securitization investors 9,064 10,840 Discover Financial Services (Parent Company) Fixed-rate senior notes 2022-2027 3.75% - 5.20% 4.16% 3,370 3,337 Fixed-rate retail notes 2022-2031 2.85% - 4.40% 3.75% 166 336 Discover Bank Fixed-rate senior bank notes (1) 2023-2030 2.45% - 4.65% 3.63% 5,406 6,213 Fixed-rate subordinated bank notes (1) 2028 4.68% 4.68% 510 515 Total long-term borrowings $ 18,516 $ 21,241 (1) The Company uses interest rate swaps to hedge portions of these long-term borrowings against changes in fair value attributable to changes in the London Interbank Offered Rate ("LIBOR") or Overnight Index Swap ("OIS") Rate. The use of these interest rate swaps impacts the carrying value of the debt. See Note 16: Derivatives and Hedging Activities. (2) DCENT floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month LIBOR + 33 to 60 basis points as of September 30, 2021. (3) The private student loan securitization trust floating-rate asset-backed security includes an issuance with the following interest rate term: Prime rate + 100 basis points as of September 30, 2021. (4) Repayment of this debt depends on the timing of principal and interest payments on the underlying private student loans. The date shown represents the final maturity date.
Schedule of Long-Term Borrowings Maturities	The following table summarizes long-term borrowings maturing over the remainder of this year, over each of the next four years and thereafter (dollars in millions): September 30, 2021 2021 $ — 2022 5,188 2023 3,324 2024 3,738 2025 529 Thereafter 5,737 Total $ 18,516

Preferred Stock (Tables)

Preferred Stock (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Schedule of Stock by Class	The table below presents a summary of the Company's non-cumulative perpetual preferred stock that is outstanding at September 30, 2021 (dollars in millions, except per depositary share amounts): Series Description Initial Issuance Date Liquidation Preference and Redemption Price per Depositary Share (1) Per Annum Dividend Rate in effect at September 30, 2021 Total Depositary Shares Authorized, Issued and Outstanding Carrying Value September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 C (2)(3)(4) Fixed-to-Floating Rate 10/31/2017 $ 1,000 5.500 % 570,000 570,000 $ 563 $ 563 D (2)(5)(6) Fixed-Rate Reset 6/22/2020 $ 1,000 6.125 % 500,000 500,000 493 493 Total Preferred Stock 1,070,000 1,070,000 $ 1,056 $ 1,056 (1) Redeemable at the redemption price plus declared and unpaid dividends. (2) Issued as depositary shares, each representing 1/100 th interest in a share of the corresponding series of preferred stock. Each preferred share has a par value of $0.01. (3) Redeemable at the Company’s option, subject to regulatory approval, either (i) in whole or in part on any dividend payment date on or after October 30, 2027, or (ii) in whole but not in part, at any time within 90 days following a regulatory capital treatment event (as defined in the certificate of designations for the Series C preferred stock). (4) Any dividends declared are payable semi-annually in arrears at a rate of 5.50% per annum until October 30, 2027. Thereafter, dividends declared will be payable quarterly in arrears at a floating rate equal to 3-month LIBOR plus a spread of 3.076% per annum. (5) Redeemable at the Company’s option, subject to regulatory approval, either (i) in whole or in part during the three-month period prior to, and including, each reset date (as defined in the certificate of designations for the Series D preferred stock) or (ii) in whole but not in part, at any time within 90 days following a regulatory capital treatment event (as defined in the certificate of designations for the Series D Preferred Stock). (6) Any dividends declared are payable semi-annually in arrears at a rate of 6.125% per annum until September 23, 2025, after which the dividend rate will reset every five years to a fixed annual rate equal to the 5-year Treasury plus a spread of 5.783%.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Loss)	Changes in each component of accumulated other comprehensive income ("AOCI") were as follows (dollars in millions): Unrealized Gains on Available-for-Sale Investment Securities, Net of Tax Losses on Cash Flow Hedges, Net of Tax Losses on Pension Plan, Net of Tax AOCI For the Three Months Ended September 30, 2021 Balance at June 30, 2021 $ 198 $ (10) $ (227) $ (39) Net change (29) — — (29) Balance at September 30, 2021 $ 169 $ (10) $ (227) $ (68) For the Three Months Ended September 30, 2020 Balance at June 30, 2020 $ 352 $ (16) $ (214) $ 122 Net change (32) 3 — (29) Balance at September 30, 2020 $ 320 $ (13) $ (214) $ 93 For the Nine Months Ended September 30, 2021 Balance at December 31, 2020 $ 284 $ (12) $ (227) $ 45 Net change (115) 2 — (113) Balance at September 30, 2021 $ 169 $ (10) $ (227) $ (68) For the Nine Months Ended September 30, 2020 Balance at December 31, 2019 $ 112 $ (17) $ (214) $ (119) Net change 208 4 — 212 Balance at September 30, 2020 $ 320 $ (13) $ (214) $ 93
Schedule of Other Comprehensive Income Before Reclassifications and Amounts Reclassified from AOCI	The following table presents each component of other comprehensive income ("OCI") before reclassifications and amounts reclassified from AOCI for each component of OCI before- and after-tax (dollars in millions): Before Tax Tax Benefit (Expense) Net of Tax For the Three Months Ended September 30, 2021 Available-for-Sale Investment Securities Net unrealized holding losses arising during the period $ (38) $ 9 $ (29) Net change $ (38) $ 9 $ (29) Cash Flow Hedges Net unrealized gains arising during the period $ — $ 1 $ 1 Amounts reclassified from AOCI — (1) (1) Net change $ — $ — $ — For the Three Months Ended September 30, 2020 Available-for-Sale Investment Securities Net unrealized holding losses arising during the period $ (42) $ 10 $ (32) Net change $ (42) $ 10 $ (32) Cash Flow Hedges Amounts reclassified from AOCI $ 4 $ (1) $ 3 Net change $ 4 $ (1) $ 3 For the Nine Months Ended September 30, 2021 Available-for-Sale Investment Securities Net unrealized holding losses arising during the period $ (152) $ 37 $ (115) Net change $ (152) $ 37 $ (115) Cash Flow Hedges Net unrealized gains arising during the period $ — $ 1 $ 1 Amounts reclassified from AOCI 2 (1) 1 Net change $ 2 $ — $ 2 For the Nine Months Ended September 30, 2020 Available-for-Sale Investment Securities Net unrealized holding gains arising during the period $ 275 $ (67) $ 208 Net change $ 275 $ (67) $ 208 Cash Flow Hedges Net unrealized losses arising during the period $ (7) $ 3 $ (4) Amounts reclassified from AOCI 11 (3) 8 Net change $ 4 $ — $ 4

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Calculation	The following table presents the calculation of the Company's effective income tax rate (dollars in millions): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Income before income taxes $ 1,402 $ 959 $ 5,703 $ 420 Income tax expense $ 311 $ 188 $ 1,321 $ 78 Effective income tax rate 22.2 % 19.6 % 23.2 % 18.6 %

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Basic and Diluted EPS	The following table presents the calculation of basic and diluted earnings per share ("EPS") (dollars and shares in millions, except per share amounts): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Numerator Net income $ 1,091 $ 771 $ 4,382 $ 342 Preferred stock dividends (30) (15) (69) (31) Net income available to common stockholders 1,061 756 4,313 311 Income allocated to participating securities (6) (5) (24) (2) Net income allocated to common stockholders $ 1,055 $ 751 $ 4,289 $ 309 Denominator Weighted-average shares of common stock outstanding 298 306 303 307 Effect of dilutive common stock equivalents — — — — Weighted-average shares of common stock outstanding and common stock equivalents 298 306 303 307 Basic earnings per common share $ 3.54 $ 2.45 $ 14.17 $ 1.00 Diluted earnings per common share $ 3.54 $ 2.45 $ 14.16 $ 1.00

Capital Adequacy (Tables)

Capital Adequacy (Tables)	9 Months Ended
	Sep. 30, 2021
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Schedule of Minimum and Well-Capitalized Requirements	The following table shows the actual capital amounts and ratios of DFS and Discover Bank and comparisons of each to the regulatory minimum and "well-capitalized" requirements (dollars in millions): Actual Minimum Capital Capital Requirements Amount Ratio (1) Amount Ratio Amount (2) Ratio (2) September 30, 2021 Total capital (to risk-weighted assets) Discover Financial Services $ 16,924 18.5 % $ 7,309 ≥8.0% $ 9,136 ≥10.0% Discover Bank $ 15,905 17.7 % $ 7,186 ≥8.0% $ 8,982 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 15,235 16.7 % $ 5,482 ≥6.0% $ 5,482 ≥6.0% Discover Bank $ 13,935 15.5 % $ 5,389 ≥6.0% $ 7,186 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 15,235 13.8 % $ 4,424 ≥4.0% N/A N/A Discover Bank $ 13,935 12.8 % $ 4,353 ≥4.0% $ 5,441 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 14,179 15.5 % $ 4,111 ≥4.5% N/A N/A Discover Bank $ 13,935 15.5 % $ 4,042 ≥4.5% $ 5,839 ≥6.5% December 31, 2020 Total capital (to risk-weighted assets) Discover Financial Services $ 14,711 16.1 % $ 7,298 ≥8.0% $ 9,123 ≥10.0% Discover Bank $ 14,507 16.1 % $ 7,214 ≥8.0% $ 9,018 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 13,006 14.3 % $ 5,474 ≥6.0% $ 5,474 ≥6.0% Discover Bank $ 12,415 13.8 % $ 5,411 ≥6.0% $ 7,214 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 13,006 10.9 % $ 4,757 ≥4.0% N/A N/A Discover Bank $ 12,415 10.5 % $ 4,709 ≥4.0% $ 5,886 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 11,950 13.1 % $ 4,105 ≥4.5% N/A N/A Discover Bank $ 12,415 13.8 % $ 4,058 ≥4.5% $ 5,862 ≥6.5% (1) Capital ratios are calculated based on the Basel III standardized approach rules, subject to applicable transition provisions, including CECL transition provisions. (2) The Basel III rules do not establish well-capitalized thresholds for these measures for bank holding companies. Existing well-capitalized thresholds established in the Federal Reserve's Regulation Y have been included where available.

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Tables)	9 Months Ended
	Sep. 30, 2021
Guarantor Obligations [Line Items]
Schedule of Maximum Potential Counterparty Exposures Related to Settlement Guarantees and Merchant Chargeback Guarantee	The following table summarizes certain information regarding merchant chargeback guarantees (dollars in millions): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Aggregate sales transaction volume (1) $ 58,107 $ 46,128 $ 160,717 $ 125,214 (1) Represents transactions processed on the Discover Network for which a potential liability exists that, in aggregate, can differ from credit card sales volume.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are as follows (dollars in millions): Quoted Price in Active Markets Significant Significant Total Balance at September 30, 2021 Assets Fair value - OCI United States Treasury and U.S. GSE securities $ 7,571 $ 9 $ — $ 7,580 Residential mortgage-backed securities - Agency — 211 — 211 Available-for-sale investment securities $ 7,571 $ 220 $ — $ 7,791 Fair value - Net income Marketable equity securities $ 600 $ — $ — $ 600 Derivative financial instruments - fair value hedges (1) $ — $ 1 $ — $ 1 Balance at December 31, 2020 Assets Fair value - OCI United States Treasury securities $ 9,354 $ — $ — $ 9,354 Residential mortgage-backed securities - Agency — 300 — 300 Available-for-sale investment securities $ 9,354 $ 300 $ — $ 9,654 Fair value - Net income Derivative financial instruments - fair value hedges (1) $ — $ 1 $ — $ 1 (1) Derivative instrument carrying values in an asset or liability position are presented as part of other assets or accrued expenses and other liabilities, respectively, in the Company's condensed consolidated statements of financial condition.
Schedule of Financial Instruments Measured at Other Than Fair Value	The following tables disclose the estimated fair value of the Company's financial assets and financial liabilities that are not required to be carried at fair value (dollars in millions): Balance at September 30, 2021 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 227 $ — $ 227 $ 223 Held-to-maturity investment securities $ — $ 227 $ — $ 227 $ 223 Net loan receivables $ — $ — $ 90,019 $ 90,019 $ 82,681 Carrying value approximates fair value (1) Cash and cash equivalents $ 12,716 $ — $ — $ 12,716 $ 12,716 Restricted cash $ 32 $ — $ — $ 32 $ 32 Accrued interest receivables (2) $ — $ 968 $ — $ 968 $ 968 Liabilities Amortized cost Time deposits (3) $ — $ 22,300 $ — $ 22,300 $ 21,831 Long-term borrowings - owed to securitization investors $ — $ 9,014 $ 110 $ 9,124 $ 9,064 Other long-term borrowings — 10,204 — 10,204 9,452 Long-term borrowings $ — $ 19,218 $ 110 $ 19,328 $ 18,516 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 124 $ — $ 124 $ 124 Balance at December 31, 2020 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 269 $ — $ 269 $ 260 Held-to-maturity investment securities $ — $ 269 $ — $ 269 $ 260 Net loan receivables $ — $ — $ 91,200 $ 91,200 $ 82,223 Carrying value approximates fair value (1) Cash and cash equivalents $ 13,564 $ — $ — $ 13,564 $ 13,564 Restricted cash $ 25 $ — $ — $ 25 $ 25 Other short-term investments $ 2,200 $ — $ — $ 2,200 $ 2,200 Accrued interest receivables (2) $ — $ 992 $ — $ 992 $ 992 Liabilities Amortized cost Time deposits (3) $ — $ 29,090 $ — $ 29,090 $ 28,269 Long-term borrowings - owed to securitization investors $ — $ 10,794 $ 130 $ 10,924 $ 10,840 Other long-term borrowings — 11,418 — 11,418 10,401 Long-term borrowings $ — $ 22,212 $ 130 $ 22,342 $ 21,241 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 233 $ — $ 233 $ 233 (1) The carrying values of these assets and liabilities approximate fair value due to their short-term nature. (2) Accrued interest receivable and payable carrying values are presented as part of other assets or accrued expenses and other liabilities, respectively, in the Company's condensed consolidated statements of financial condition. (3) Excludes deposits without contractually defined maturities for all periods presented.

Derivatives and Hedging Activ_2

Derivatives and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value and Outstanding Notional Amounts of Derivative Instruments and Related Collateral Balances	The following table summarizes the fair value (including accrued interest) and outstanding notional amounts of derivative instruments and related collateral balances (dollars in millions): September 30, 2021 December 31, 2020 Notional Number of Outstanding Derivative Contracts Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities Derivatives designated as hedges Interest rate swaps—cash flow hedge $ 250 1 $ — $ — $ 250 $ — $ — Interest rate swaps—fair value hedge $ 8,275 10 1 — $ 11,625 1 — Derivatives not designated as hedges Foreign exchange forward contracts (1) $ 26 6 — — $ 24 — — Interest rate swaps $ 5 1 — — $ — — — Total gross derivative assets/liabilities (2) 1 — 1 — Less: collateral held/posted (3) — — — — Total net derivative assets/liabilities $ 1 $ — $ 1 $ — (1) The foreign exchange forward contracts have notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 788 million as of September 30, 2021, and notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 596 million as of December 31, 2020. (2) In addition to the derivatives disclosed in the table, the Company enters into forward contracts to purchase when-issued mortgage-backed securities as part of its community reinvestment initiatives. At September 30, 2021, the Company had no outstanding contracts. At December 31, 2020, the Company had one outstanding contract with a total notional amount of $27 million and an immaterial fair value. (3) Collateral amounts, which consist of cash and investment securities, are limited to the related derivative asset/liability balance and do not include excess collateral received/pledged.
Schedule of Hedged Items in Fair Value Hedging Relationship	The following amounts were recorded on the statements of financial condition related to cumulative basis adjustments for fair value hedges (dollars in millions): September 30, 2021 December 31, 2020 Carrying Amount of Hedged Liability Cumulative Amount of Fair Value Hedging Adjustment Increasing the Carrying Amount of Hedged Liability Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increasing the Carrying Amount of Hedged Liability Long-term borrowings $ 8,885 $ 115 $ 11,881 $ 281
Schedule of Impact of the Derivative Instruments on Income	The following table summarizes the impact of the derivative instruments on income and indicates where within the condensed consolidated financial statements such impact is reported (dollars in millions): Location and Amount of (Losses) Gains Recognized on the Condensed Consolidated Statements of Income Interest Expense Deposits Long-Term Borrowings Other Income For the Three Months Ended September 30, 2021 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (156) $ (113) $ 18 The effects of cash flow and fair value hedging Gains (losses) on cash flow hedging relationship Amounts reclassified from OCI into earnings $ — $ — $ — Gains on fair value hedging relationships Gains on hedged items $ — $ 45 $ — Gains (losses) on interest rate swaps — (9) — Total gains on fair value hedging relationships $ — $ 36 $ — For the Three Months Ended September 30, 2020 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (287) $ (126) $ 17 The effects of cash flow and fair value hedging Gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (4) $ — $ — Gains on fair value hedging relationships Gains on hedged items $ — $ 59 $ — Gains (losses) on interest rate swaps — (9) — Total gains on fair value hedging relationships $ — $ 50 $ — The effects of derivatives not designated in hedging relationships Gains (losses) on derivatives not designated as hedges $ — $ — $ (1) Location and Amount of (Losses) Gains Recognized on the Condensed Consolidated Statements of Income Interest Expense Deposits Long-Term Borrowings Other Income For the Nine Months Ended September 30, 2021 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (519) $ (356) $ 47 The effects of cash flow and fair value hedging Gains (losses) on cash flow hedging relationship Amounts reclassified from OCI into earnings $ — $ (2) $ — Gains on fair value hedging relationships Gains on hedged items $ — $ 167 $ — Gains (losses) on interest rate swaps — (38) — Total gains on fair value hedging relationships $ — $ 129 $ — For the Nine Months Ended September 30, 2020 Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded $ (1,000) $ (479) $ 59 The effects of cash flow and fair value hedging Losses on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (9) $ (2) $ — Gains on fair value hedging relationship Gains (losses) on hedged items $ — $ (326) $ — Gains on interest rate swaps — 434 — Total gains on fair value hedging relationships $ — $ 108 $ —

Segment Disclosures (Tables)

Segment Disclosures (Tables)	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Schedule of Segment Disclosures	The following table presents segment data (dollars in millions): Digital Payment Total For the Three Months Ended September 30, 2021 Interest income Credit card loans $ 2,193 $ — $ 2,193 Private student loans 184 — 184 Personal loans 219 — 219 Other loans 30 — 30 Other interest income 48 — 48 Total interest income 2,674 — 2,674 Interest expense 269 — 269 Net interest income 2,405 — 2,405 Provision for credit losses 185 — 185 Other income (loss) 447 (75) 372 Other expense 1,151 39 1,190 Income (loss) before income taxes $ 1,516 $ (114) $ 1,402 For the Three Months Ended September 30, 2020 Interest income Credit card loans $ 2,171 $ — $ 2,171 Private student loans 182 — 182 Personal loans 237 — 237 Other loans 27 — 27 Other interest income 64 — 64 Total interest income 2,681 — 2,681 Interest expense 416 — 416 Net interest income 2,265 — 2,265 Provision for credit losses 750 — 750 Other income 371 78 449 Other expense 969 36 1,005 Income before income taxes $ 917 $ 42 $ 959 Digital Payment Total For the Nine Months Ended September 30, 2021 Interest income Credit card loans $ 6,452 $ — $ 6,452 Private student loans 554 — 554 Personal loans 662 — 662 Other loans 85 — 85 Other interest income 156 — 156 Total interest income 7,909 — 7,909 Interest expense 875 — 875 Net interest income 7,034 — 7,034 Provision for credit losses (45) — (45) Other income 1,284 833 2,117 Other expense 3,290 203 3,493 Income before income tax expense $ 5,073 $ 630 $ 5,703 For the Nine Months Ended September 30, 2020 Interest income Credit card loans $ 6,760 $ — $ 6,760 Private student loans 569 — 569 Personal loans 722 — 722 Other loans 78 — 78 Other interest income 206 — 206 Total interest income 8,335 — 8,335 Interest expense 1,482 — 1,482 Net interest income 6,853 — 6,853 Provision for credit losses 4,603 — 4,603 Other income 1,091 320 1,411 Other expense 3,069 172 3,241 Income before income tax expense $ 272 $ 148 $ 420

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Revenue from Contracts with Customers Disaggregated by Business Segment	The following table presents revenue from contracts with customers disaggregated by business segment and reconciles revenue from contracts with customers to total other income (dollars in millions): Digital Banking Payment Services Total For the Three Months Ended September 30, 2021 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 280 $ 19 $ 299 Protection products revenue 43 — 43 Transaction processing revenue — 58 58 Other income 3 15 18 Total other income subject to ASC 606 (2) 326 92 418 Other income not subject to ASC 606 Loan fee income 121 — 121 Unrealized gains (losses) on equity investments — (167) (167) Total other income (loss) not subject to ASC 606 121 (167) (46) Total other income (loss) by operating segment $ 447 $ (75) $ 372 For the Three Months Ended September 30, 2020 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 225 $ 13 $ 238 Protection products revenue 44 — 44 Transaction processing revenue — 50 50 Other income 2 15 17 Total other income subject to ASC 606 (2) 271 78 349 Other income not subject to ASC 606 Loan fee income 100 — 100 Total other income not subject to ASC 606 100 — 100 Total other income by operating segment $ 371 $ 78 $ 449 Digital Banking Payment Services Total For the Nine Months Ended September 30, 2021 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 826 $ 53 $ 879 Protection products revenue 129 — 129 Transaction processing revenue — 167 167 Other (loss) income (4) 51 47 Total other income subject to ASC 606 (2) 951 271 1,222 Other income not subject to ASC 606 Loan fee income 333 — 333 Unrealized gains on equity investments — 562 562 Total other income not subject to ASC 606 333 562 895 Total other income by operating segment $ 1,284 $ 833 $ 2,117 For the Nine Months Ended September 30, 2020 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 644 $ 47 $ 691 Protection products revenue 135 — 135 Transaction processing revenue — 143 143 Other income 8 51 59 Total other income subject to ASC 606 (2) 787 241 1,028 Other income not subject to ASC 606 Loan fee income 304 — 304 Realized gains on equity investments — 79 79 Total other income not subject to ASC 606 304 79 383 Total other income by operating segment $ 1,091 $ 320 $ 1,411 (1) Net of rewards, including Cashback Bonus rewards, of $689 million and $514 million for the three months ended September 30, 2021 and 2020, respectively, and $1.8 billion and $1.4 billion for the nine months ended September 30, 2021 and 2020, respectively. (2) Excludes deposit product fees that are reported within net interest income, which were immaterial for the three and nine months ended September 30, 2021 and 2020.

Background and Basis of Prese_3

Background and Basis of Presentation (Narrative) (Details)	9 Months Ended
	Sep. 30, 2021segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments (in number of segments)	2

Investments (Narrative) (Detail

Investments (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)securities	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)securities	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)securities
Investment Holdings [Line Items]
Proceeds from the sale of available-for-sale securities	$ 5,000,000	$ 0	$ 5,000,000	$ 0
Recognized gains (losses) on available-for-sale securities		0		0
Contingent liabilities related to equity method investments	0		0
Unrealized (losses) gains on equity investments	$ (167,000,000)	$ 0	$ 562,000,000	$ 0
US Treasury and Government
Investment Holdings [Line Items]
Available-for-sale investment securities, continuous unrealized loss position, number of securities | securities	3		3		0
Available-for-sale investment securities, continuous unrealized loss position, less than 12 months, fair value	$ 118,000,000		$ 118,000,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0
Payment Services [Member]
Investment Holdings [Line Items]
Equity securities without readily determinable fair value	31,000,000		31,000,000		$ 35,000,000
Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Affordable housing project equity method investments	324,000,000		324,000,000		324,000,000
Contingent liabilities related to affordable housing project equity method investments	52,000,000		52,000,000		79,000,000
Other Assets [Member] | Payment Services [Member]
Investment Holdings [Line Items]
Fair value of marketable equity securities	600,000,000		600,000,000		8,000,000
Other Assets [Member] | Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Equity method investments	366,000,000		366,000,000		353,000,000
Other Liabilities [Member] | Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Contingent liabilities related to equity method investments	$ 64,000,000		$ 64,000,000		$ 93,000,000

Investments (Schedule of Invest

Investments (Schedule of Investment Securities) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Investment Holdings [Line Items]
Other short-term investments		$ 0	$ 2,200
Investment securities		8,014	9,914
US Treasury Bill Securities [Member] | Asset Not Pledged as Collateral [Member]
Investment Holdings [Line Items]
Other short-term investments	[1]	0	2,200
US Treasury and Government
Investment Holdings [Line Items]
Investment securities	[2],[3]	7,580	9,354
Residential Mortgage-Backed Securities - Agency [Member] | Asset Not Pledged as Collateral [Member]
Investment Holdings [Line Items]
Investment securities	[2]	434	560
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Derivative collateral		$ 56	$ 117
[1]	(1) Includes United States Treasury bills with maturity dates greater than 90 days but less than one year at the time of acquisition.
[2]	Consists of securities issued by Fannie Mae, Freddie Mac, Ginnie Mae, or the Federal Home Loan Bank.
[3]	Includes $56 million and $117 million of United States Treasury securities pledged as swap collateral as of September 30, 2021 and December 31, 2020, respectively.

Investments (Schedule of Amorti

Investments (Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value) (Details) - USD ($) $ in Millions		Sep. 30, 2021		Dec. 31, 2020
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]	$ 7,566		$ 9,277
Available-for-sale investment securities, gross unrealized gains	[1]	225		377
Available-for-sale investment securities, gross unrealized losses	[1]	0		0
Available-for-sale investment securities, fair value	[1]	7,791		9,654
Held-to-maturity investment securities, amortized cost	[2]	223		260
Held-to-maturity investment securities, gross unrealized gains	[2]	5		9
Held-to-maturity investment securities, gross unrealized losses	[2]	(1)		0
Held-to-maturity investment securities, fair value	[2]	227		269
US Treasury and Government
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]	7,362
Available-for-sale investment securities, gross unrealized gains	[1]	218
Available-for-sale investment securities, gross unrealized losses	[1]	0
Available-for-sale investment securities, fair value	[1]	7,580
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]			8,987
Available-for-sale investment securities, gross unrealized gains	[1]			367
Available-for-sale investment securities, gross unrealized losses	[1]			0
Available-for-sale investment securities, fair value	[1]			9,354
Residential Mortgage-Backed Securities - Agency [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]	204	[3]	290
Available-for-sale investment securities, gross unrealized gains	[1]	7		10
Available-for-sale investment securities, gross unrealized losses	[1]	0		0
Available-for-sale investment securities, fair value	[1]	211	[3]	300
Held-to-maturity investment securities, amortized cost	[2],[4]	223	[3]	260
Held-to-maturity investment securities, gross unrealized gains	[2],[4]	5		9
Held-to-maturity investment securities, gross unrealized losses	[2],[4]	(1)		0
Held-to-maturity investment securities, fair value	[2],[4]	$ 227	[3]	$ 269
[1]	Available-for-sale investment securities are reported at fair value.
[2]	Held-to-maturity investment securities are reported at amortized cost.
[3]	Maturities of RMBS are reflective of the contractual maturities of the investment.
[4]	Amounts represent residential mortgage-backed securities ("RMBS") that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.

Investments (Schedule of Maturi

Investments (Schedule of Maturities of Available-for-Sale Debt Securities and Held-to-Maturity Debt Securities) (Details) - USD ($) $ in Millions		Sep. 30, 2021		Dec. 31, 2020
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost		$ 2,618
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost		4,758
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost		183
Available-for-sale investment securities, debt maturities, after ten years, amortized cost		7
Available-for-sale investment securities, amortized cost	[1]	7,566		$ 9,277
Held-to-maturity investment securities, debt maturities, one year or less, amortized cost		0
Held-to-maturity investment securities, debt maturities, after one year through five years, amortized cost		0
Held-to-maturity investment securities, debt maturities, after five years through ten years, amortized cost		0
Held-to-maturity investment securities, debt maturities, after ten years, amortized cost		223
Held-to-maturity investment securities, amortized cost	[2]	223		260
Available-for-sale investment securities, debt maturities, one year or less, fair value		2,643
Available-for-sale investment securities, debt maturities, after one year through five years, fair value		4,952
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value		188
Available-for-sale investment securities, debt maturities, after ten years, fair value		8
Available-for-sale investment securities, fair value	[1]	7,791		9,654
Held-to-maturity investment securities, debt maturities, one year or less, fair value		0
Held-to-maturity investment securities, debt maturities, after one year through five years, fair value		0
Held-to-maturity investment securities, debt maturities, after five years through ten years, fair value		0
Held-to-maturity investment securities, debt maturities, after ten years, fair value		227
Held-to-maturity investment securities, fair value	[2]	227		269
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]			8,987
Available-for-sale investment securities, fair value	[1]			9,354
US Treasury and Government
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost		2,616
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost		4,737
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost		9
Available-for-sale investment securities, debt maturities, after ten years, amortized cost		0
Available-for-sale investment securities, amortized cost	[1]	7,362
Available-for-sale investment securities, debt maturities, one year or less, fair value		2,641
Available-for-sale investment securities, debt maturities, after one year through five years, fair value		4,931
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value		8
Available-for-sale investment securities, debt maturities, after ten years, fair value		0
Available-for-sale investment securities, fair value	[1]	7,580
Residential Mortgage-Backed Securities - Agency [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost	[3]	2
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost	[3]	21
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost	[3]	174
Available-for-sale investment securities, debt maturities, after ten years, amortized cost	[3]	7
Available-for-sale investment securities, amortized cost	[1]	204	[3]	290
Held-to-maturity investment securities, debt maturities, one year or less, amortized cost	[3]	0
Held-to-maturity investment securities, debt maturities, after one year through five years, amortized cost	[3]	0
Held-to-maturity investment securities, debt maturities, after five years through ten years, amortized cost	[3]	0
Held-to-maturity investment securities, debt maturities, after ten years, amortized cost	[3]	223
Held-to-maturity investment securities, amortized cost	[2],[4]	223	[3]	260
Available-for-sale investment securities, debt maturities, one year or less, fair value	[3]	2
Available-for-sale investment securities, debt maturities, after one year through five years, fair value	[3]	21
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value	[3]	180
Available-for-sale investment securities, debt maturities, after ten years, fair value	[3]	8
Available-for-sale investment securities, fair value	[1]	211	[3]	300
Held-to-maturity investment securities, debt maturities, one year or less, fair value	[3]	0
Held-to-maturity investment securities, debt maturities, after one year through five years, fair value	[3]	0
Held-to-maturity investment securities, debt maturities, after five years through ten years, fair value	[3]	0
Held-to-maturity investment securities, debt maturities, after ten years, fair value	[3]	227
Held-to-maturity investment securities, fair value	[2],[4]	$ 227	[3]	$ 269
[1]	Available-for-sale investment securities are reported at fair value.
[2]	Held-to-maturity investment securities are reported at amortized cost.
[3]	Maturities of RMBS are reflective of the contractual maturities of the investment.
[4]	Amounts represent residential mortgage-backed securities ("RMBS") that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.

Loan Receivables (Narrative) (D

Loan Receivables (Narrative) (Details) $ in Millions	3 Months Ended							9 Months Ended
	Sep. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020	Sep. 30, 2021USD ($)segment	Sep. 30, 2020USD ($)	Jan. 01, 2020USD ($)	Dec. 31, 2019USD ($)	[1]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan portfolio segments (in segments) | segment								2
Allowance for credit losses	$ 6,861	$ 7,026		$ 8,226	$ 8,226	$ 8,184		$ 6,861	$ 8,226	$ 5,844	$ 3,383
Allowance for credit losses, period increase (decrease)	$ (165)							$ (1,400)
Expected Future Peak Unemployment Rate	6.10%							6.10%
Expected EOY Unemployment Rate	5.50%							5.50%
Expected EOY2 Unemployment Rate	4.00%							4.00%
Expected EY Annualized Increase in GDP	6.40%							6.40%
Expected EOY2 Annualized Increase in GDP	3.50%							3.50%
Reasonable and supportable forecast period	18 months	18 months	18 months	18 months	18 months	18 months	12 months
Reversion period								12 months	12 months
Percentage of defaulted loans that were charged off at the end of the month in which they defaulted (in percent)	62.00%				65.00%			66.00%	52.00%
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Delinquent Loan Qualification Period								30 days
Private Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private student loans in repayment	$ 5,300			$ 5,700				$ 5,300
Private student loans in forbearance	63			117				$ 63
Personal Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum period of payment reduction for the temporary reduced payment program (in months)								12 months
Maximum repayment term for permanent modification programs (in years)								9 years
Credit Card Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	5,298	$ 5,409		$ 6,491	$ 6,491	$ 6,491		$ 5,298	$ 6,491	$ 4,550	$ 2,883
Credit Card Loans [Member] | Credit Card Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum period of payment reduction for the temporary reduced payment program (in months)								12 months
Interest and fees forgiven due to credit card loan modification program	$ 7				$ 13			$ 28	$ 52
Credit Card Loans [Member] | Credit Card Loans [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Permanent workout program maturity (in months)								72 months
[1]	Prior to the adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Loan Receivables (Schedule of L

Loan Receivables (Schedule of Loan Receivables) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	[1]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		$ 89,542		$ 90,449
Allowance for credit losses		(6,861)	$ (7,026)	(8,226)	$ (8,226)	$ (8,184)	$ (5,844)	$ (3,383)
Net loan receivables		82,681		82,223
Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		24,751		27,546
Allowance for credit losses		(1,436)		(1,936)
Credit Card Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[2]	24,536		27,296
Allowance for credit losses	[2]	(1,436)		(1,936)
Net loan receivables		23,100		25,360
Seller's interest		11,640		10,575
Private Student Loan Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		215		250
Credit Card Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[3],[4]	70,320		71,472
Allowance for credit losses		(5,298)	(5,409)	(6,491)	(6,491)	(6,491)	(4,550)	(2,883)
Accrued interest receivable		379		420
Credit Card Loans [Member] | Credit Card Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investors' interest		12,900		16,700
Seller's interest		11,600		10,600
Total Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[5]	19,222		18,977
Total Other Loans [Member] | Private Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[5],[6]	10,184		9,954
Allowance for credit losses		(857)	(828)	(840)	(840)	(799)	(653)	(148)
Accrued interest receivable		503		469
Total Other Loans [Member] | Private Student Loans [Member] | Private Student Loan Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral		215		250
Total Other Loans [Member] | Personal Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[5]	6,890		7,177
Allowance for credit losses		(662)	(745)	(857)	(857)	(857)	(613)	(348)
Accrued interest receivable		41		49
Total Other Loans [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[5]	2,148		1,846
Allowance for credit losses		(44)	$ (44)	(38)	$ (38)	$ (37)	$ (28)	$ (4)
Accrued interest receivable		$ 6		$ 6
[1]	Prior to the adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	The Company maintains its allowance for credit losses at an amount equal to lifetime expected credit losses associated with all loan receivables, which includes all loan receivables in the trusts. Therefore, the credit risk associated with the transferred receivables is fully reflected on the Company's statements of financial condition in accordance with GAAP.
[3]	Amounts include carrying values of $12.9 billion and $16.7 billion underlying investors' interest in trust debt at September 30, 2021 and December 31, 2020, respectively, and $11.6 billion and $10.6 billion in seller's interest at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[4]	Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $379 million and $420 million at September 30, 2021 and December 31, 2020, respectively.
[5]	Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $503 million, $41 million and $6 million, respectively, at September 30, 2021 and $469 million, $49 million and $6 million, respectively, at December 31, 2020.
[6]	Amounts include carrying values of $215 million and $250 million in loans pledged as collateral against the notes issued from a private student loan securitization trust at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.

Loan Receivables (Schedule of C

Loan Receivables (Schedule of Credit Risk Profile by FICO Score and Origination Year) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		$ 89,542	$ 90,449
Revolving line-of-credit arrangements that were converted to term loans as a result of a TDR program, ending balance		881	1,000
Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[1],[2]	70,320	71,472
Credit Card Loans [Member] | FICO Score, 660 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card	[3]	$ 59,005	$ 58,950
FICO distribution %, credit card	[3]	84.00%	82.00%
Credit Card Loans [Member] | FICO Score, Less Than 660 Or No Score [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card	[3]	$ 11,315	$ 12,522
FICO distribution %, credit card	[3]	16.00%	18.00%
Total Other Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[4]	$ 19,222	$ 18,977
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[4],[5]	10,184	9,954
Total Other Loans [Member] | Private Student Loans [Member] | FICO Score, 660 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021	[6],[7]	$ 1,011
FICO distribution %, originated in 2021	[6],[7]	94.00%
Loan receivables, originated in 2020	[6],[7]	$ 1,593	$ 1,173
FICO distribution %, originated in 2020	[6],[7]	97.00%	95.00%
Loan receivables, originated in 2019	[6],[7]	$ 1,485	$ 1,659
FICO distribution %, originated in 2019	[6],[7]	96.00%	96.00%
Loan receivables, originated in 2018	[6],[7]	$ 1,185	$ 1,365
FICO distribution %, originated in 2018	[6],[7]	95.00%	96.00%
Loan receivables, originated in 2017	[6],[7]	$ 898	$ 1,052
FICO distribution %, originated in 2017	[6],[7]	95.00%	95.00%
Loan receivables, originated prior to 2017	[6],[7]	$ 3,521	$ 4,219
FICO distribution %, originated prior to 2017	[6],[7]	95.00%	94.00%
Loan receivables	[6],[7]	$ 9,693	$ 9,468
FICO distribution %, loan receivables	[6],[7]	95.00%	95.00%
Total Other Loans [Member] | Private Student Loans [Member] | FICO Score, Less Than 660 Or No Score [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021	[6],[7]	$ 70
FICO distribution %, originated in 2021	[6],[7]	6.00%
Loan receivables, originated in 2020	[6],[7]	$ 54	$ 60
FICO distribution %, originated in 2020	[6],[7]	3.00%	5.00%
Loan receivables, originated in 2019	[6],[7]	$ 56	$ 61
FICO distribution %, originated in 2019	[6],[7]	4.00%	4.00%
Loan receivables, originated in 2018	[6],[7]	$ 58	$ 61
FICO distribution %, originated in 2018	[6],[7]	5.00%	4.00%
Loan receivables, originated in 2017	[6],[7]	$ 52	$ 57
FICO distribution %, originated in 2017	[6],[7]	5.00%	5.00%
Loan receivables, originated prior to 2017	[6],[7]	$ 201	$ 247
FICO distribution %, originated prior to 2017	[6],[7]	5.00%	6.00%
Loan receivables	[6],[7]	$ 491	$ 486
FICO distribution %, loan receivables	[6],[7]	5.00%	5.00%
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[4]	$ 6,890	$ 7,177
Total Other Loans [Member] | Personal Loans [Member] | FICO Score, 660 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021		$ 2,541
FICO distribution %, originated in 2021		99.00%
Loan receivables, originated in 2020		$ 1,921	$ 2,880
FICO distribution %, originated in 2020		98.00%	99.00%
Loan receivables, originated in 2019		$ 1,291	$ 2,183
FICO distribution %, originated in 2019		95.00%	96.00%
Loan receivables, originated in 2018		$ 550	$ 1,018
FICO distribution %, originated in 2018		92.00%	92.00%
Loan receivables, originated in 2017		$ 276	$ 558
FICO distribution %, originated in 2017		88.00%	89.00%
Loan receivables, originated prior to 2017		$ 87	$ 227
FICO distribution %, originated prior to 2017		84.00%	86.00%
Loan receivables		$ 6,666	$ 6,866
FICO distribution %, loan receivables		97.00%	96.00%
Total Other Loans [Member] | Personal Loans [Member] | FICO Score, Less Than 660 Or No Score [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021		$ 18
FICO distribution %, originated in 2021		1.00%
Loan receivables, originated in 2020		$ 37	$ 25
FICO distribution %, originated in 2020		2.00%	1.00%
Loan receivables, originated in 2019		$ 66	$ 90
FICO distribution %, originated in 2019		5.00%	4.00%
Loan receivables, originated in 2018		$ 51	$ 90
FICO distribution %, originated in 2018		8.00%	8.00%
Loan receivables, originated in 2017		$ 36	$ 69
FICO distribution %, originated in 2017		12.00%	11.00%
Loan receivables, originated prior to 2017		$ 16	$ 37
FICO distribution %, originated prior to 2017		16.00%	14.00%
Loan receivables		$ 224	$ 311
FICO distribution %, loan receivables		3.00%	4.00%
[1]	Amounts include carrying values of $12.9 billion and $16.7 billion underlying investors' interest in trust debt at September 30, 2021 and December 31, 2020, respectively, and $11.6 billion and $10.6 billion in seller's interest at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[2]	Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $379 million and $420 million at September 30, 2021 and December 31, 2020, respectively.
[3]	Amounts include $881 million and $1.0 billion of revolving line-of-credit arrangements that were converted to term loans as a result of a troubled debt restructuring ("TDR") program as of September 30, 2021 and December 31, 2020, respectively.
[4]	Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $503 million, $41 million and $6 million, respectively, at September 30, 2021 and $469 million, $49 million and $6 million, respectively, at December 31, 2020.
[5]	Amounts include carrying values of $215 million and $250 million in loans pledged as collateral against the notes issued from a private student loan securitization trust at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[6]	A majority of private student loan originations occur in the third quarter and disbursements can span multiple calendar years.
[7]	FICO score represents the higher credit score of the cosigner or borrower.

Loan Receivables (Schedule of D

Loan Receivables (Schedule of Delinquent Loans by Origination Year) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		$ 89,542	$ 90,449
Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[1],[2]	70,320	71,472
Total Other Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[3]	19,222	18,977
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[3],[4]	10,184	9,954
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[3]	6,890	7,177
30-89 Days Delinquent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		736	910
30-89 Days Delinquent [Member] | Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card		573	739
30-89 Days Delinquent [Member] | Total Other Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		163	171
30-89 Days Delinquent [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021	[5]	0
Loan receivables, originated in 2020	[5]	4	0
Loan receivables, originated in 2019	[5]	11	3
Loan receivables, originated in 2018	[5]	14	9
Loan receivables, originated in 2017	[5]	15	12
Loan receivables, originated prior to 2017	[5]	78	86
Loan receivables	[5]	122	110
30-89 Days Delinquent [Member] | Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021		2
Loan receivables, originated in 2020		7	5
Loan receivables, originated in 2019		12	18
Loan receivables, originated in 2018		8	15
Loan receivables, originated in 2017		5	10
Loan receivables, originated prior to 2017		2	5
Loan receivables		36	53
90 or More Days Delinquent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		522	795
90 or More Days Delinquent [Member] | Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card		467	739
90 or More Days Delinquent [Member] | Total Other Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		55	56
90 or More Days Delinquent [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021	[5]	0
Loan receivables, originated in 2020	[5]	1	0
Loan receivables, originated in 2019	[5]	2	1
Loan receivables, originated in 2018	[5]	4	3
Loan receivables, originated in 2017	[5]	5	4
Loan receivables, originated prior to 2017	[5]	24	20
Loan receivables	[5]	36	28
90 or More Days Delinquent [Member] | Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021		0
Loan receivables, originated in 2020		2	2
Loan receivables, originated in 2019		5	9
Loan receivables, originated in 2018		3	7
Loan receivables, originated in 2017		2	5
Loan receivables, originated prior to 2017		1	2
Loan receivables		13	25
Total Past Due [Member] | Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card		1,040	1,478
Total Past Due [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021	[5]	0
Loan receivables, originated in 2020	[5]	5	0
Loan receivables, originated in 2019	[5]	13	4
Loan receivables, originated in 2018	[5]	18	12
Loan receivables, originated in 2017	[5]	20	16
Loan receivables, originated prior to 2017	[5]	102	106
Loan receivables	[5]	158	138
Total Past Due [Member] | Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2021		2
Loan receivables, originated in 2020		9	7
Loan receivables, originated in 2019		17	27
Loan receivables, originated in 2018		11	22
Loan receivables, originated in 2017		7	15
Loan receivables, originated prior to 2017		3	7
Loan receivables		$ 49	$ 78
[1]	Amounts include carrying values of $12.9 billion and $16.7 billion underlying investors' interest in trust debt at September 30, 2021 and December 31, 2020, respectively, and $11.6 billion and $10.6 billion in seller's interest at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[2]	Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $379 million and $420 million at September 30, 2021 and December 31, 2020, respectively.
[3]	Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $503 million, $41 million and $6 million, respectively, at September 30, 2021 and $469 million, $49 million and $6 million, respectively, at December 31, 2020.
[4]	Amounts include carrying values of $215 million and $250 million in loans pledged as collateral against the notes issued from a private student loan securitization trust at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[5]	Private student loans may include a deferment period, during which customers are not required to make payments while enrolled in school at least half time as determined by the school. During a deferment period, these loans do not advance into delinquency.

Loan Receivables (Schedule of_2

Loan Receivables (Schedule of Changes in the Allowance for Credit Losses) (Details) - USD ($) $ in Millions		Jan. 01, 2020		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		$ 3,383	[1]	$ 7,026	$ 8,184	$ 8,226	$ 3,383	[1]
Provision for credit losses(1)	[2]			160	710	(47)	4,586
Charge-offs				(556)	(842)	(1,991)	(2,767)
Recoveries				231	174	673	563
Net charge-offs				(325)	(668)	(1,318)	(2,204)
Allowance for credit losses, balance at end of period		5,844		6,861	8,226	6,861	8,226
Cumulative effect of ASU No. 2016-13 adoption	[3]	2,461
Credit loss build (release) on unfunded commitments				25	40	2	17
Credit Card Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		2,883	[1]	5,409	6,491	6,491	2,883	[1]
Provision for credit losses(1)	[2]			178	604	(18)	3,916
Charge-offs				(495)	(759)	(1,778)	(2,480)
Recoveries				206	155	603	505
Net charge-offs				(289)	(604)	(1,175)	(1,975)
Allowance for credit losses, balance at end of period		4,550		5,298	6,491	5,298	6,491
Cumulative effect of ASU No. 2016-13 adoption	[3]	1,667
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		148	[1]	828	799	840	148	[1]
Provision for credit losses(1)	[2]			46	55	61	233
Charge-offs				(23)	(20)	(63)	(62)
Recoveries				6	6	19	16
Net charge-offs				(17)	(14)	(44)	(46)
Allowance for credit losses, balance at end of period		653		857	840	857	840
Cumulative effect of ASU No. 2016-13 adoption	[3]	505
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		348	[1]	745	857	857	348	[1]
Provision for credit losses(1)	[2]			(64)	49	(96)	426
Charge-offs				(38)	(62)	(150)	(224)
Recoveries				19	13	51	42
Net charge-offs				(19)	(49)	(99)	(182)
Allowance for credit losses, balance at end of period		613		662	857	662	857
Cumulative effect of ASU No. 2016-13 adoption	[3]	265
Total Other Loans [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		4	[1]	44	37	38	4	[1]
Provision for credit losses(1)	[2]			0	2	6	11
Charge-offs				0	(1)	0	(1)
Recoveries				0	0	0	0
Net charge-offs				0	(1)	0	(1)
Allowance for credit losses, balance at end of period		28		$ 44	$ 38	$ 44	$ 38
Cumulative effect of ASU No. 2016-13 adoption	[3]	$ 24
[1]	Prior to the adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Excludes a $25 million and $40 million reclassification of the liability for expected credit losses on unfunded commitments for the three months ended September 30, 2021 and 2020, respectively, and $2 million and $17 million for the nine months ended September 30, 2021 and 2020, respectively, as the liability is recorded in accrued expenses and other liabilities in the Company's condensed consolidated statements of financial condition.
[3]	Represents the adjustment to the allowance for credit losses due to the adoption of ASU No. 2016-13 on January 1, 2020.

Loan Receivables (Schedule of N

Loan Receivables (Schedule of Net Charge-offs of Interest and Fee Revenues on Loan Receivables) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Receivables [Abstract]
Interest and fees accrued subsequently charged-off, net of recoveries (recorded as a reduction of interest income)	$ 57	$ 114	$ 232	$ 393
Fees accrued subsequently charged-off, net of recoveries (recorded as a reduction to other income)	$ 15	$ 27	$ 59	$ 95

Loan Receivables (Schedule of_3

Loan Receivables (Schedule of Delinquent and Non-Accruing Loans) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Loan receivables, 90 or more days delinquent and accruing		$ 479		$ 479		$ 737
Loan receivables, total non-accruing	[1]	232		232		243
Loan receivables		89,542		89,542		90,449
30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		736		736		910
90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		522		522		795
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loan receivables		1,258		1,258		1,705
Credit Card Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, 90 or more days delinquent and accruing		430		430		687
Loan receivables, total non-accruing	[1]	201		201		209
Loan receivables	[2],[3]	70,320		70,320		71,472
Estimated gross interest income that would have been recorded based on original terms		6	$ 7	21	$ 25
Credit Card Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, credit card		573		573		739
Credit Card Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, credit card		467		467		739
Credit Card Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loan receivables, credit card		1,040		1,040		1,478
Total Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, 90 or more days delinquent and accruing		49		49		50
Loan receivables, total non-accruing	[1]	31		31		34
Loan receivables	[4]	19,222		19,222		18,977
Total Other Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		163		163		171
Total Other Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		55		55		56
Total Other Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loan receivables		218		218		227
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, 90 or more days delinquent and accruing		35		35		27
Loan receivables, total non-accruing	[1]	8		8		12
Loan receivables	[4],[5]	10,184		10,184		9,954
Total Other Loans [Member] | Private Student Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables	[6]	122		122		110
Total Other Loans [Member] | Private Student Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables	[6]	36		36		28
Total Other Loans [Member] | Private Student Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loan receivables		158		158		138
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, 90 or more days delinquent and accruing		12		12		23
Loan receivables, total non-accruing	[1]	9		9		12
Loan receivables	[4]	6,890		6,890		7,177
Total Other Loans [Member] | Personal Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		36		36		53
Total Other Loans [Member] | Personal Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		13		13		25
Total Other Loans [Member] | Personal Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loan receivables		49		49		78
Total Other Loans [Member] | Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, 90 or more days delinquent and accruing		2		2		0
Loan receivables, total non-accruing	[1]	14		14		10
Loan receivables	[4]	2,148		2,148		1,846
Total Other Loans [Member] | Other Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		5		5		8
Total Other Loans [Member] | Other Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables		6		6		3
Total Other Loans [Member] | Other Loans [Member] | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loan receivables		$ 11		$ 11		$ 11
[1]	The Company estimates that the gross interest income that would have been recorded under the original terms of non-accruing credit card loans was $6 million and $7 million for the three months ended September 30, 2021 and 2020, respectively, and $21 million and $25 million for the nine months ended September 30, 2021 and 2020, respectively. The Company does not separately track the amount of gross interest income that would have been recorded under the original terms of loans. Instead, the Company estimated this amount based on customers' current balances and most recent interest rates.
[2]	Amounts include carrying values of $12.9 billion and $16.7 billion underlying investors' interest in trust debt at September 30, 2021 and December 31, 2020, respectively, and $11.6 billion and $10.6 billion in seller's interest at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[3]	Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $379 million and $420 million at September 30, 2021 and December 31, 2020, respectively.
[4]	Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $503 million, $41 million and $6 million, respectively, at September 30, 2021 and $469 million, $49 million and $6 million, respectively, at December 31, 2020.
[5]	Amounts include carrying values of $215 million and $250 million in loans pledged as collateral against the notes issued from a private student loan securitization trust at September 30, 2021 and December 31, 2020, respectively. See Note 4: Credit Card and Private Student Loan Securitization Activities for additional information.
[6]	Private student loans may include a deferment period, during which customers are not required to make payments while enrolled in school at least half time as determined by the school. During a deferment period, these loans do not advance into delinquency.

Loan Receivables (Schedule of_4

Loan Receivables (Schedule of Loans That Entered a Modification Program During the Period) (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021USD ($)accounts	Sep. 30, 2020USD ($)accounts	Sep. 30, 2021USD ($)accounts	Sep. 30, 2020USD ($)accounts
Credit Card Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts that entered a TDR program during the period, number of accounts (in accounts) | accounts	[1]	13,964	20,779	48,887	130,869
Accounts that entered a TDR program during the period, balances	[1]	$ 86	$ 150	$ 315	$ 875
Accounts that entered a TDR program during the period and were converted from revolving line-of-credit arrangements to term loans, balances		$ 72	$ 143	$ 288	$ 529
Total Other Loans [Member] | Private Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts that entered a TDR program during the period, number of accounts (in accounts) | accounts		102	118	355	1,767
Accounts that entered a TDR program during the period, balances		$ 2	$ 2	$ 7	$ 32
Total Other Loans [Member] | Personal Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts that entered a TDR program during the period, number of accounts (in accounts) | accounts		888	2,505	3,102	6,315
Accounts that entered a TDR program during the period, balances		$ 10	$ 33	$ 38	$ 83
[1]	Accounts that entered a credit card TDR program include $72 million and $143 million that were converted from revolving line-of-credit arrangements to term loans during the three months ended September 30, 2021 and 2020, respectively, and $288 million and $529 million for the nine months ended September 30, 2021 and 2020, respectively.

Loan Receivables (Schedule of T

Loan Receivables (Schedule of Troubled Debt Restructurings That Subsequently Defaulted) (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021USD ($)accounts	Sep. 30, 2020USD ($)accounts	Sep. 30, 2021USD ($)missed_paymentsaccounts	Sep. 30, 2020USD ($)accounts
Credit Card Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs that subsequently defaulted, number of accounts (in accounts) | accounts	[1],[2]	3,679	8,983	14,205	41,285
TDRs that subsequently defaulted, aggregated outstanding balances upon default | $	[1],[2]	$ 21	$ 52	$ 84	$ 235
Amount of missed payments after which a customer defaults from a TDR program (in payments) | missed_payments				2
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs that subsequently defaulted, number of accounts (in accounts) | accounts	[3]	83	272	214	876
TDRs that subsequently defaulted, aggregated outstanding balances upon default | $	[3]	$ 2	$ 6	$ 5	$ 18
Delinquency days to default (in days)				60 days
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs that subsequently defaulted, number of accounts (in accounts) | accounts	[1]	399	624	1,287	2,446
TDRs that subsequently defaulted, aggregated outstanding balances upon default | $	[1]	$ 6	$ 9	$ 18	$ 36
Amount of missed payments after which a customer defaults from a TDR program (in payments) | missed_payments				2
[1]	For credit card loans and personal loans, a customer defaults from a loan modification program after either two consecutive missed payments or at charge-off, depending on the program. The outstanding balance upon default is generally the loan balance at the end of the month prior to default.
[2]	For credit card loans that default from a temporary program, accounts revert to the pre-modification terms and charging privileges remain suspended in most cases.
[3]	For student loans, a customer defaults from a loan modification after they are 60 or more days delinquent. The outstanding balance upon default is generally the loan balance at the end of the month prior to default

Credit Card and Private Stude_3

Credit Card and Private Student Loan Securitization Activities (Narrative) (Details)	9 Months Ended
	Sep. 30, 2021classes
Variable Interest Entity, Primary Beneficiary [Member] | Discover Card Execution Note Trust [Member] | Credit Card Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Number of classes of securities in debt structure (in classes)	4

Credit Card and Private Stude_4

Credit Card and Private Student Loan Securitization Activities (Schedule of Restricted Credit Card Securitized Assets) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	[1]
Variable Interest Entity [Line Items]
Restricted cash		$ 32		$ 25	$ 576
Loan receivables		89,542		90,449
Allowance for credit losses allocated to securitized loan receivables		(6,861)	$ (7,026)	(8,226)	$ (8,226)	$ (8,184)	$ (5,844)	$ (3,383)
Net loan receivables		82,681		82,223
Other		3,858		3,586
Total assets		108,544		112,889
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash		32		25
Loan receivables		24,751		27,546
Allowance for credit losses allocated to securitized loan receivables		(1,436)		(1,936)
Other		4		4
Variable Interest Entity, Primary Beneficiary [Member] | Credit Card Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Restricted cash		23		16
Investors' interests held by third-party investors		8,925		10,600
Investors' interests held by wholly-owned subsidiaries of Discover Bank		3,971		6,121
Seller's interest		11,640		10,575
Loan receivables	[2]	24,536		27,296
Allowance for credit losses allocated to securitized loan receivables	[2]	(1,436)		(1,936)
Net loan receivables		23,100		25,360
Other		3		3
Total assets		$ 23,126		$ 25,379
[1]	Prior to the adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	The Company maintains its allowance for credit losses at an amount equal to lifetime expected credit losses associated with all loan receivables, which includes all loan receivables in the trusts. Therefore, the credit risk associated with the transferred receivables is fully reflected on the Company's statements of financial condition in accordance with GAAP.

Credit Card and Private Stude_5

Credit Card and Private Student Loan Securitization Activities (Schedule of Restricted Student Loan Securitized Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Variable Interest Entity [Line Items]
Restricted cash	$ 32	$ 25	$ 576
Loan receivables	89,542	90,449
Total assets	108,544	112,889
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash	32	25
Loan receivables	24,751	27,546
Variable Interest Entity, Primary Beneficiary [Member] | Private Student Loan Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Restricted cash	9	9
Loan receivables	215	250
Total assets	$ 224	$ 259

Intangible Assets (Details)

Intangible Assets (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, net					$ 1,000,000	$ 95,000,000
Trade Names [Member]
Indefinite-lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 92,000,000	$ 36,000,000	$ 92,000,000	$ 36,000,000
Intangible assets, net					0
International Transaction Processing Rights [Member]
Indefinite-lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		$ 23,000,000		$ 23,000,000
Intangible assets, net					$ 0

Deposits (Narrative) (Details)

Deposits (Narrative) (Details)	9 Months Ended
	Sep. 30, 2021channels
Deposits [Abstract]
Deposits source channels (in number of channels)	2

Deposits (Schedule of Interest

Deposits (Schedule of Interest Bearing Deposit Accounts) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Deposits [Abstract]
Certificates of deposit in amounts less than $100,000		$ 14,592	$ 19,105
Certificates of deposit in amounts $100,000 or greater	[1]	7,239	9,164
Savings deposits, including money market deposit accounts		49,295	47,426
Total interest-bearing deposits		71,126	75,695
Certificates of deposit equal to or greater than $250,000		$ 2,000	$ 2,600
[1]	Includes $2.0 billion and $2.6 billion in certificates of deposit equal to or greater than $250,000, the Federal Deposit Insurance Corporation ("FDIC") insurance limit, as of September 30, 2021 and December 31, 2020, respectively.

Deposits (Schedule of $100,000

Deposits (Schedule of $100,000 or More Certificates of Deposit Maturities) (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Deposits [Abstract]
Three months or less		$ 1,458
Over three months through six months		1,640
Over six months through twelve months		2,711
Over twelve months		1,430
Total	[1]	$ 7,239	$ 9,164
[1]	Includes $2.0 billion and $2.6 billion in certificates of deposit equal to or greater than $250,000, the Federal Deposit Insurance Corporation ("FDIC") insurance limit, as of September 30, 2021 and December 31, 2020, respectively.

Deposits (Schedule of Certifica

Deposits (Schedule of Certificates of Deposit Maturities) (Details) $ in Millions	Sep. 30, 2021USD ($)
Deposits [Abstract]
2021	$ 4,171
2022	11,133
2023	2,663
2024	1,451
2025	870
Thereafter	1,543
Total	$ 21,831

Long-Term Borrowings (Narrative

Long-Term Borrowings (Narrative) (Details) - Discover Card Master Trust I and Discover Card Execution Note Trust [Member] - Securitized Debt [Member] $ in Billions	Sep. 30, 2021USD ($)
Debt Instrument [Line Items]
Total commitment of secured credit facilities	$ 4
Total used commitment of secured credit facilities	$ 0

Long-Term Borrowings (Schedule

Long-Term Borrowings (Schedule of Long-Term Borrowings and Weighted Average Interest Rates) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		$ 18,516	$ 21,241
Variable Interest Entity, Primary Beneficiary [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		9,064	10,840
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		$ 8,954	10,710
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Fixed-Rate Asset-Backed Securities [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	[1]	2.01%
Long-term borrowings (in dollars)	[1]	$ 5,607	6,041
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Fixed-Rate Asset-Backed Securities [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[1]	0.58%
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Fixed-Rate Asset-Backed Securities [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.04%
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	[2]	0.54%
Long-term borrowings (in dollars)	[2]	$ 3,347	4,669
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[2]	0.41%
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[2]	0.68%
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | 1-Month LIBOR [Member]
Debt Instrument [Line Items]
Interest rate terms		1-month LIBOR + 33 to 60 basis points
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | 1-Month LIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.33%
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | 1-Month LIBOR [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.60%
Securitized Debt [Member] | Student Loan Trust [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		$ 110	130
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	[3],[4]	4.25%
Long-term borrowings (in dollars)	[3],[4]	$ 110	130
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[3],[4]	4.25%
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[3],[4]	4.25%
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Interest rate terms		Prime rate + 100 basis points
Basis spread on variable rate		1.00%
Securitized Debt [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		$ 9,064	10,840
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Senior Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		4.16%
Long-term borrowings (in dollars)		$ 3,370	3,337
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Senior Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate		3.75%
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Senior Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate		5.20%
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Retail Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		3.75%
Long-term borrowings (in dollars)		$ 166	336
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Retail Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate		2.85%
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Retail Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate		4.40%
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	[1]	3.63%
Long-term borrowings (in dollars)	[1]	$ 5,406	6,213
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[1]	2.45%
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.65%
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	[1]	4.68%
Long-term borrowings (in dollars)	[1]	$ 510	$ 515
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.68%
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.68%
[1]	The Company uses interest rate swaps to hedge portions of these long-term borrowings against changes in fair value attributable to changes in the London Interbank Offered Rate ("LIBOR") or Overnight Index Swap ("OIS") Rate. The use of these interest rate swaps impacts the carrying value of the debt. See Note 16: Derivatives and Hedging Activities.
[2]	DCENT floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month LIBOR + 33 to 60 basis points as of September 30, 2021.
[3]	Repayment of this debt depends on the timing of principal and interest payments on the underlying private student loans. The date shown represents the final maturity date.
[4]	The private student loan securitization trust floating-rate asset-backed security includes an issuance with the following interest rate term: Prime rate + 100 basis points as of September 30, 2021.

Long-Term Borrowings (Schedul_2

Long-Term Borrowings (Schedule of Long-Term Borrowings Maturities) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
2021	$ 0
2021R	0
2022	5,188
2023	3,324
2024	3,738
2025	529
Thereafter	5,737
Total	$ 18,516	$ 21,241

Preferred Stock (Details)

Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions		Jul. 22, 2020	Oct. 31, 2017	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Preferred stock, par or stated value per share				$ 0.01	$ 0.01
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, initial issue date	[1]		Oct. 31, 2017
Preferred stock, earliest redemption date				Oct. 30, 2027
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, initial issue date	[1]	Jun. 22, 2020
Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, depositary shares issued (in number of depositary shares)				1,070,000	1,070,000
Proceeds from issuance of preferred stock, net				$ 1,056	$ 1,056
Preferred Stock [Member] | Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	[1],[2],[3]			$ 1,000
Preferred stock, redemption price per share	[1],[2],[3]			$ 1,000
Preferred Stock, Dividend Rate, Percentage	[1],[4]			5.50%
Preferred stock, depositary shares issued (in number of depositary shares)	[1]			570,000	570,000
Proceeds from issuance of preferred stock, net	[1]			$ 563	$ 563
Depositary shares represented by one preferred share				100
Preferred stock, par or stated value per share				$ 0.01
Redemption period of preferred stock following regulatory capital treatment event				90 days
Preferred stock dividend payment rate variable, rate to be used in future periods				3-month LIBOR
Preferred Stock [Member] | Series C Preferred Stock [Member] | Three-Month London Interbank Offered Rate (LIBOR)
Class of Stock [Line Items]
Preferred stock basis spread on variable rate, rate to be used in future periods				3.076%
Preferred Stock [Member] | Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	[1],[3],[5]			$ 1,000
Preferred stock, redemption price per share	[1],[3],[5]			$ 1,000
Preferred Stock, Dividend Rate, Percentage	[1],[6]			6.125%
Preferred stock, depositary shares issued (in number of depositary shares)	[1]			500,000	500,000
Proceeds from issuance of preferred stock, net	[1]			$ 493	$ 493
Depositary shares represented by one preferred share				100
Preferred stock, par or stated value per share				$ 0.01
Redemption period of preferred stock following regulatory capital treatment event				90 days
Preferred stock dividend payment rate variable, rate to be used in future periods				5-year Treasury
Dividend rate reset				5 years
Preferred Stock [Member] | Series D Preferred Stock | Five-Year Treasury Rate
Class of Stock [Line Items]
Preferred stock basis spread on variable rate, rate to be used in future periods				5.783%
[1]	Issued as depositary shares, each representing 1/100 th interest in a share of the corresponding series of preferred stock. Each preferred share has a par value of $0.01.
[2]	Redeemable at the Company’s option, subject to regulatory approval, either (i) in whole or in part on any dividend payment date on or after October 30, 2027, or (ii) in whole but not in part, at any time within 90 days following a regulatory capital treatment event (as defined in the certificate of designations for the Series C preferred stock).
[3]	Redeemable at the redemption price plus declared and unpaid dividends.
[4]	Any dividends declared are payable semi-annually in arrears at a rate of 5.50% per annum until October 30, 2027. Thereafter, dividends declared will be payable quarterly in arrears at a floating rate equal to 3-month LIBOR plus a spread of 3.076% per annum.
[5]	Redeemable at the Company’s option, subject to regulatory approval, either (i) in whole or in part during the three-month period prior to, and including, each reset date (as defined in the certificate of designations for the Series D preferred stock) or (ii) in whole but not in part, at any time within 90 days following a regulatory capital treatment event (as defined in the certificate of designations for the Series D Preferred Stock).
[6]	Any dividends declared are payable semi-annually in arrears at a rate of 6.125% per annum until September 23, 2025, after which the dividend rate will reset every five years to a fixed annual rate equal to the 5-year Treasury plus a spread of 5.783%.

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Schedule of Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period			$ 45
Net change in accumulated other comprehensive income (loss), net of tax	$ (29)	$ (29)	(113)	$ 212
Accumulated other comprehensive income (loss), net of tax, balance at end of period	(68)		(68)
Unrealized Gains (Losses) on Available-for-Sale Investment Securities, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period	198	352	284	112
Net change in accumulated other comprehensive income (loss), net of tax	(29)	(32)	(115)	208
Accumulated other comprehensive income (loss), net of tax, balance at end of period	169	320	169	320
Gains (Losses) on Cash Flow Hedges, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period	(10)	(16)	(12)	(17)
Net change in accumulated other comprehensive income (loss), net of tax	0	3	2	4
Accumulated other comprehensive income (loss), net of tax, balance at end of period	(10)	(13)	(10)	(13)
Gains (Losses) on Pension Plan, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period	(227)	(214)	(227)	(214)
Net change in accumulated other comprehensive income (loss), net of tax	0	0	0	0
Accumulated other comprehensive income (loss), net of tax, balance at end of period	(227)	(214)	(227)	(214)
AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period	(39)	122	45	(119)
Net change in accumulated other comprehensive income (loss), net of tax	(29)	(29)	(113)	212
Accumulated other comprehensive income (loss), net of tax, balance at end of period	$ (68)	$ 93	$ (68)	$ 93

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Schedule of Other Comprehensive Income Before Reclassifications and Amounts Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Available-for-sale investment securities, net unrealized holding gains (losses) arising during the period, before tax	$ (38)	$ (42)	$ (152)	$ 275
Available-for-sale investment securities, net unrealized holding gains (losses) arising during the period, tax benefit (expense)	9	10	37	(67)
Available-for-sale investment securities, net unrealized holding gains (losses) arising during the period, net of tax	(29)	(32)	(115)	208
Available-for-sale investment securities, net change, before tax	(38)	(42)	(152)	275
Available-for-sale investment securities, net change, tax benefit (expense)	9	10	37	(67)
Available-for-sale investment securities, net change, net of tax	(29)	(32)	(115)	208
Cash flow hedges, net unrealized gains (losses) arising during the period, before tax	0		0	(7)
Cash flow hedges, net unrealized gains (losses) arising during the period, tax benefit (expense)	1		1	3
Cash flow hedges, net unrealized gains (losses) arising during the period, net of tax	1		1	(4)
Cash flow hedges, amounts reclassified from AOCI, before tax	0	4	2	11
Cash flow hedges, amounts reclassified from AOCI, tax benefit (expense)	(1)	(1)	(1)	(3)
Cash flow hedges, amounts reclassified from AOCI, net of tax	(1)	3	1	8
Cash flow hedges, net change, before tax	0	4	2	4
Cash flow hedges, net change, tax benefit (expense)	0	(1)	0	0
Cash flow hedges, net change, net of tax	$ 0	$ 3	$ 2	$ 4

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Increase (decrease) in income tax expense/benefit, amount	$ 123	$ 1,200

Income Taxes (Schedule of Effec

Income Taxes (Schedule of Effective Income Tax Rate Calculation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	$ 1,402	$ 959	$ 5,703	$ 420
Income tax expense	$ 311	$ 188	$ 1,321	$ 78
Effective income tax rate (in percent)	22.20%	19.60%	23.20%	18.60%

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Basic and Diluted EPS ) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income	$ 1,091	$ 771	$ 4,382	$ 342
Preferred stock dividends	(30)	(15)	(69)	(31)
Net income available to common stockholders	1,061	756	4,313	311
Income allocated to participating securities	(6)	(5)	(24)	(2)
Net income allocated to common stockholders	1,055	751	4,289	309
Net Income (Loss) Available to Common Stockholders, Diluted	$ 1,055	$ 751	$ 4,289	$ 309
Denominator:
Weighted-average shares of common stock outstanding	298	306	303	307
Effect of dilutive common stock equivalents	0	0	0	0
Weighted-average shares of common stock outstanding and common stock equivalents	298	306	303	307
Basic earnings per common share (in dollars per share)	$ 3.54	$ 2.45	$ 14.17	$ 1
Diluted earnings per common share (in dollars per share)	$ 3.54	$ 2.45	$ 14.16	$ 1

Capital Adequacy (Schedule of M

Capital Adequacy (Schedule of Minimum and Well-Capitalized Requirements) (Details) $ in Millions		Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Parent Company [Member]
Compliance with Regulatory Capital Requirements [Line Items]
Total capital to risk-weighted assets, actual amount		$ 16,924	$ 14,711
Total capital to risk-weighted assets, actual ratio (in percent)	[1]	0.185	0.161
Total capital to risk-weighted assets, minimum capital requirements, amount		$ 7,309	$ 7,298
Total capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		0.080	0.080
Total capital to risk-weighted assets, capital requirements to be classified as well-capitalized, amount	[2]	$ 9,136	$ 9,123
Total capital to risk-weighted assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	0.100	0.100
Tier I capital to risk-weighted assets, actual amount		$ 15,235	$ 13,006
Tier I capital to risk-weighted assets, actual ratio (in percent)	[1]	0.167	0.143
Tier I capital to risk-weighted assets, minimum capital requirements, amount		$ 5,482	$ 5,474
Tier I capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		0.060	0.060
Tier I capital to risk-weighted assets, capital requirements to be classified as well-capitalized, amount	[2]	$ 5,482	$ 5,474
Tier I capital to risk-weighted assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	0.060	0.060
Tier I capital to average assets, actual amount		$ 15,235	$ 13,006
Tier I capital to average assets, actual ratio (in percent)	[1]	0.138	0.109
Tier I capital to average assets, minimum capital requirements, amount		$ 4,424	$ 4,757
Tier I capital to average assets, minimum capital requirements, ratio (in percent)		0.040	0.040
CET1 capital to risk-weighted assets, actual amount		$ 14,179	$ 11,950
CET1 capital to risk-weighted assets, actual ratio (in percent)	[1]	0.155	0.131
CET1 capital to risk-weighted assets, minimum capital requirements, amount		$ 4,111	$ 4,105
CET1 capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		4.50%	4.50%
Discover Bank [Member]
Compliance with Regulatory Capital Requirements [Line Items]
Total capital to risk-weighted assets, actual amount		$ 15,905	$ 14,507
Total capital to risk-weighted assets, actual ratio (in percent)	[1]	0.177	0.161
Total capital to risk-weighted assets, minimum capital requirements, amount		$ 7,186	$ 7,214
Total capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		0.080	0.080
Total capital to risk-weighted assets, capital requirements to be classified as well-capitalized, amount	[2]	$ 8,982	$ 9,018
Total capital to risk-weighted assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	0.100	0.100
Tier I capital to risk-weighted assets, actual amount		$ 13,935	$ 12,415
Tier I capital to risk-weighted assets, actual ratio (in percent)	[1]	0.155	0.138
Tier I capital to risk-weighted assets, minimum capital requirements, amount		$ 5,389	$ 5,411
Tier I capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		0.060	0.060
Tier I capital to risk-weighted assets, capital requirements to be classified as well-capitalized, amount	[2]	$ 7,186	$ 7,214
Tier I capital to risk-weighted assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	0.080	0.080
Tier I capital to average assets, actual amount		$ 13,935	$ 12,415
Tier I capital to average assets, actual ratio (in percent)	[1]	0.128	0.105
Tier I capital to average assets, minimum capital requirements, amount		$ 4,353	$ 4,709
Tier I capital to average assets, minimum capital requirements, ratio (in percent)		0.040	0.040
Tier I capital to average assets, capital requirements to be classified as well-capitalized, amount	[2]	$ 5,441	$ 5,886
Tier I capital to average assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	0.050	0.050
CET1 capital to risk-weighted assets, actual amount		$ 13,935	$ 12,415
CET1 capital to risk-weighted assets, actual ratio (in percent)	[1]	0.155	0.138
CET1 capital to risk-weighted assets, minimum capital requirements, amount		$ 4,042	$ 4,058
CET1 capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		4.50%	4.50%
CET1 capital to risk-weighted assets, capital requirements to be classified as well-capitalized, amount	[2]	$ 5,839	$ 5,862
CET1 capital to risk-weighted assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	6.50%	6.50%
[1]	Capital ratios are calculated based on the Basel III standardized approach rules, subject to applicable transition provisions, including CECL transition provisions.
[2]	The Basel III rules do not establish well-capitalized thresholds for these measures for bank holding companies. Existing well-capitalized thresholds established in the Federal Reserve's Regulation Y have been included where available.

Commitments, Contingencies an_3

Commitments, Contingencies and Guarantees (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Commitments, Contingencies and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 80
Contingent liabilities related to equity method investments	0
Escrow deposits and settlement withholdings	15	$ 16
Commitments to Extend Credit [Member]
Commitments, Contingencies and Guarantees [Line Items]
Unused commitments to extend credit for loans	$ 220,100

Commitments, Contingencies an_4

Commitments, Contingencies and Guarantees (Schedule of Maximum Potential Counterparty Exposures Related to Settlement Guarantees and Merchant Chargeback Guarantee) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Merchant Chargeback Guarantees [Member]
Loss Contingencies [Line Items]
Aggregate sales transaction volume	[1]	$ 58,107	$ 46,128	$ 160,717	$ 125,214
[1]	Represents transactions processed on the Discover Network for which a potential liability exists that, in aggregate, can differ from credit card sales volume.

Litigation and Regulatory Mat_2

Litigation and Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Dec. 22, 2020	Sep. 30, 2021	Sep. 30, 2021
Loss Contingencies [Line Items]
Litigation settlement, expense		$ 51	$ 54
Unfavorable Regulatory Action [Member] | Consumer Financial Protection Bureau Consent Order [Member]
Loss Contingencies [Line Items]
Amount of civil money penalty for consent order	$ 25
Maximum [Member] | Pending and Threatened Litigation [Member]
Loss Contingencies [Line Items]
Loss contingency, range of possible loss, portion not accrued		$ 250	$ 250
Minimum [Member] | Unfavorable Regulatory Action [Member] | Consumer Financial Protection Bureau Consent Order [Member]
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 10

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets measured at fair value on a non-recurring basis	$ 0	$ 92
Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities, par value	$ 201	$ 201
Available for sale securities, weighted average coupon rate (in percent)	3.24%	3.24%
Available for sale securities, weighted average remaining maturity (in years)		2 years

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions		Sep. 30, 2021		Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value	[1]	$ 7,791		$ 9,654
US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value	[1]	7,580
Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value	[1]	211	[2]	300
U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value	[1]			9,354
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		7,791		9,654
Fair value of marketable equity securities		600
Fair Value, Recurring [Member] | Interest Rate Swaps [Member] | Fair Value Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	[3]	1		1
Fair Value, Recurring [Member] | US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		7,580
Fair Value, Recurring [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		211		300
Fair Value, Recurring [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value				9,354
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		7,571		9,354
Fair value of marketable equity securities		600
Fair Value, Recurring [Member] | Level 1 [Member] | Interest Rate Swaps [Member] | Fair Value Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	[3]	0		0
Fair Value, Recurring [Member] | Level 1 [Member] | US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		7,571
Fair Value, Recurring [Member] | Level 1 [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		0		0
Fair Value, Recurring [Member] | Level 1 [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value				9,354
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		220		300
Fair value of marketable equity securities		0
Fair Value, Recurring [Member] | Level 2 [Member] | Interest Rate Swaps [Member] | Fair Value Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	[3]	1		1
Fair Value, Recurring [Member] | Level 2 [Member] | US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		9
Fair Value, Recurring [Member] | Level 2 [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		211		300
Fair Value, Recurring [Member] | Level 2 [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value				0
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		0		0
Fair value of marketable equity securities		0
Fair Value, Recurring [Member] | Level 3 [Member] | Interest Rate Swaps [Member] | Fair Value Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	[3]	0		0
Fair Value, Recurring [Member] | Level 3 [Member] | US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		0
Fair Value, Recurring [Member] | Level 3 [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		$ 0		0
Fair Value, Recurring [Member] | Level 3 [Member] | U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value				$ 0
[1]	Available-for-sale investment securities are reported at fair value.
[2]	Maturities of RMBS are reflective of the contractual maturities of the investment.
[3]	Derivative instrument carrying values in an asset or liability position are presented as part of other assets or accrued expenses and other liabilities, respectively, in the Company's condensed consolidated statements of financial condition.

Fair Value Measurements (Sche_2

Fair Value Measurements (Schedule of Financial Instruments Measured at Other Than Fair Value) (Details) - USD ($) $ in Millions		Sep. 30, 2021		Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	[1]	$ 227		$ 269
Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	[1],[2]	227	[3]	269
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		227		269
Net loan receivables		90,019		91,200
Cash and cash equivalents	[4]	12,716		13,564
Restricted cash	[4]	32		25
Other short-term investments, fair value	[4]			2,200
Accrued interest receivables	[4],[5]	968		992
Time deposits	[6]	22,300		29,090
Long-term borrowings		19,328		22,342
Accrued interest payables	[4],[5]	124		233
Estimated Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		9,124		10,924
Estimated Fair Value [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		10,204		11,418
Estimated Fair Value [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		227		269
Estimated Fair Value [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		0		0
Net loan receivables		0		0
Cash and cash equivalents	[4]	12,716		13,564
Restricted cash	[4]	32		25
Other short-term investments, fair value	[4]			2,200
Accrued interest receivables	[4],[5]	0		0
Time deposits	[6]	0		0
Long-term borrowings		0		0
Accrued interest payables	[4],[5]	0		0
Estimated Fair Value [Member] | Level 1 [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		0		0
Estimated Fair Value [Member] | Level 1 [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		0		0
Estimated Fair Value [Member] | Level 1 [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		0		0
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		227		269
Net loan receivables		0		0
Cash and cash equivalents	[4]	0		0
Restricted cash	[4]	0		0
Other short-term investments, fair value	[4]			0
Accrued interest receivables	[4],[5]	968		992
Time deposits	[6]	22,300		29,090
Long-term borrowings		19,218		22,212
Accrued interest payables	[4],[5]	124		233
Estimated Fair Value [Member] | Level 2 [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		9,014		10,794
Estimated Fair Value [Member] | Level 2 [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		10,204		11,418
Estimated Fair Value [Member] | Level 2 [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		227		269
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		0		0
Net loan receivables		90,019		91,200
Cash and cash equivalents	[4]	0		0
Restricted cash	[4]	0		0
Other short-term investments, fair value	[4]			0
Accrued interest receivables	[4],[5]	0		0
Time deposits	[6]	0		0
Long-term borrowings		110		130
Accrued interest payables	[4],[5]	0		0
Estimated Fair Value [Member] | Level 3 [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		110		130
Estimated Fair Value [Member] | Level 3 [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		0		0
Estimated Fair Value [Member] | Level 3 [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		0		0
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		223		260
Net loan receivables		82,681		82,223
Cash and cash equivalents	[4]	12,716		13,564
Restricted cash	[4]	32		25
Other short-term investments, fair value	[4]			2,200
Accrued interest receivables	[4],[5]	968		992
Time deposits	[6]	21,831		28,269
Long-term borrowings		18,516		21,241
Accrued interest payables	[4],[5]	124		233
Carrying Value [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		9,064		10,840
Carrying Value [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		9,452		10,401
Carrying Value [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		$ 223		$ 260
[1]	Held-to-maturity investment securities are reported at amortized cost.
[2]	Amounts represent residential mortgage-backed securities ("RMBS") that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.
[3]	Maturities of RMBS are reflective of the contractual maturities of the investment.
[4]	The carrying values of these assets and liabilities approximate fair value due to their short-term nature.
[5]	Accrued interest receivable and payable carrying values are presented as part of other assets or accrued expenses and other liabilities, respectively, in the Company's condensed consolidated statements of financial condition.
[6]	Excludes deposits without contractually defined maturities for all periods presented.

Derivatives and Hedging Activ_3

Derivatives and Hedging Activities (Narrative) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021transactions	Sep. 30, 2021USD ($)transactions
Derivative [Line Items]
DerivativeNumberOfTerminatedInstrumentsAssociatedWithCashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	1	1
Interest Rate Swaps [Member] | Cash Flow Hedging [Member] | Designated as Hedges [Member]
Derivative [Line Items]
Derivative, number of outstanding derivative contracts (in transactions)	1	1
Interest Expense [Member]
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months | $		$ 3
Financing Receivable [Member]
Derivative [Line Items]
Initial maximum period for cash flow hedges (in years)	2 years	2 years

Derivatives and Hedging Activ_4

Derivatives and Hedging Activities (Schedule of Fair Value and Outstanding Notional Amounts of Derivative Instruments and Related Collateral Balances) (Details) € in Millions, ₨ in Millions, £ in Millions, $ in Millions, $ in Millions		Sep. 30, 2021USD ($)transactions		Sep. 30, 2021EUR (€)transactions	Sep. 30, 2021GBP (£)transactions	Sep. 30, 2021SGD ($)transactions	Sep. 30, 2021INR (₨)transactions	Dec. 31, 2020USD ($)transactions		Dec. 31, 2020EUR (€)transactions	Dec. 31, 2020GBP (£)transactions	Dec. 31, 2020SGD ($)transactions	Dec. 31, 2020INR (₨)transactions
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	$ 1						$ 1
Derivative liabilities	[1]	0						0
Collateral held, derivative assets	[2]	0						0
Collateral posted, derivative liabilities	[2]	0						0
Total net derivative assets		1						1
Total net derivative liabilities		0						0
Designated as Hedges [Member] | Cash Flow Hedging [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 250						250
Derivative, number of outstanding derivative contracts (in transactions) | transactions		1		1	1	1	1
Derivative assets		$ 0						0
Derivative liabilities		0						0
Designated as Hedges [Member] | Fair Value Hedging [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 8,275						11,625
Derivative, number of outstanding derivative contracts (in transactions) | transactions		10		10	10	10	10
Derivative assets		$ 1						1
Derivative liabilities		0						0
Not Designated as Hedges [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 5						0
Derivative, number of outstanding derivative contracts (in transactions) | transactions		1		1	1	1	1
Derivative assets		$ 0						0
Derivative liabilities		0						0
Not Designated as Hedges [Member] | Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 26	[3]	€ 6	£ 6	$ 1	₨ 788	24	[3]	€ 6	£ 6	$ 1	₨ 596
Derivative, number of outstanding derivative contracts (in transactions) | transactions		6		6	6	6	6
Derivative assets		$ 0						0
Derivative liabilities		$ 0						0
Not Designated as Hedges [Member] | When-Issued Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount								$ 27
Derivative, number of outstanding derivative contracts (in transactions) | transactions		0		0	0	0	0	1		1	1	1	1
[1]	In addition to the derivatives disclosed in the table, the Company enters into forward contracts to purchase when-issued mortgage-backed securities as part of its community reinvestment initiatives. At September 30, 2021, the Company had no outstanding contracts. At December 31, 2020, the Company had one outstanding contract with a total notional amount of $27 million and an immaterial fair value.
[2]	Collateral amounts, which consist of cash and investment securities, are limited to the related derivative asset/liability balance and do not include excess collateral received/pledged.
[3]	The foreign exchange forward contracts have notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 788 million as of September 30, 2021, and notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 596 million as of December 31, 2020.

Derivatives and Hedging Activ_5

Derivatives and Hedging Activities Derivatives and Hedging Activities (Schedule of Hedged Items in a Fair Value Hedging Relationship) (Details) - Long-term Borrowings [Member] - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Schedule of Hedged Items in Fair Value Hedging Relationship [Line Items]
Carrying amount of hedged assets/liabilities	$ 8,885	$ 11,881
Cumulative amount of fair value hedging adjustment increasing (decreasing) the carrying amount of hedged assets/liabilities	$ 115	$ 281

Derivatives and Hedging Activ_6

Derivatives and Hedging Activities (Schedule of Impact of the Derivative Instruments on Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Amounts reclassified from OCI into earnings, cash flow hedges	$ 0	$ (4)	$ (2)	$ (11)
Interest Expense [Member] | Deposits [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded	(156)	(287)	(519)	(1,000)
Interest Expense [Member] | Deposits [Member] | Designated as Hedges [Member] | Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amounts reclassified from OCI into earnings, cash flow hedges	0	(4)	0	(9)
Gains (losses) on hedged items, fair value hedges	0	0	0	0
Gains (losses) on interest rate swaps, fair value hedges	0	0	0	0
Total gains (losses) on fair value hedges	0	0	0	0
Interest Expense [Member] | Deposits [Member] | Not Designated as Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedges		0
Interest Expense [Member] | Long-term Borrowings [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded	(113)	(126)	(356)	(479)
Interest Expense [Member] | Long-term Borrowings [Member] | Designated as Hedges [Member] | Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amounts reclassified from OCI into earnings, cash flow hedges	0	0	(2)	(2)
Gains (losses) on hedged items, fair value hedges	45	59	167	(326)
Gains (losses) on interest rate swaps, fair value hedges	(9)	(9)	(38)	434
Total gains (losses) on fair value hedges	36	50	129	108
Interest Expense [Member] | Long-term Borrowings [Member] | Not Designated as Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedges		0
Interest Income | Credit Card Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded		2,171
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the condensed consolidated statements of income, where the effects of fair value or cash flow hedges are recorded	18	17	47	59
Other Income [Member] | Designated as Hedges [Member] | Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amounts reclassified from OCI into earnings, cash flow hedges	0	0	0	0
Gains (losses) on hedged items, fair value hedges	0	0	0	0
Gains (losses) on interest rate swaps, fair value hedges	0	0	0	0
Total gains (losses) on fair value hedges	$ 0	0	$ 0	$ 0
Other Income [Member] | Not Designated as Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedges		$ (1)

Segment Disclosures (Narrative)

Segment Disclosures (Narrative) (Details)	9 Months Ended
	Sep. 30, 2021segment
Segment Reporting [Abstract]
Number of reportable segments (in number of segments)	2

Segment Disclosures (Schedule o

Segment Disclosures (Schedule of Segment Disclosures) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Interest income	$ 2,674	$ 2,681	$ 7,909	$ 8,335
Interest expense	269	416	875	1,482
Net interest income	2,405	2,265	7,034	6,853
Provision for credit losses	185	750	(45)	4,603
Other income	372	449	2,117	1,411
Other expense	1,190	1,005	3,493	3,241
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	1,402	959	5,703	420
Credit Card Loans [Member]
Segment Reporting Information [Line Items]
Interest income	2,193	2,171	6,452	6,760
Total Other Loans [Member] | Private Student Loans [Member]
Segment Reporting Information [Line Items]
Interest income	184	182	554	569
Total Other Loans [Member] | Personal Loans [Member]
Segment Reporting Information [Line Items]
Interest income	219	237	662	722
Total Other Loans [Member] | Other Loans [Member]
Segment Reporting Information [Line Items]
Interest income	30	27	85	78
Unallocated Financing Receivables | Other [Member]
Segment Reporting Information [Line Items]
Interest income	48	64	156	206
Operating Segments [Member] | Digital Banking [Member]
Segment Reporting Information [Line Items]
Interest income	2,674	2,681	7,909	8,335
Interest expense	269	416	875	1,482
Net interest income	2,405	2,265	7,034	6,853
Provision for credit losses	185	750	(45)	4,603
Other income	447	371	1,284	1,091
Other expense	1,151	969	3,290	3,069
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	1,516	917	5,073	272
Operating Segments [Member] | Digital Banking [Member] | Credit Card Loans [Member]
Segment Reporting Information [Line Items]
Interest income	2,193	2,171	6,452	6,760
Operating Segments [Member] | Digital Banking [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Segment Reporting Information [Line Items]
Interest income	184	182	554	569
Operating Segments [Member] | Digital Banking [Member] | Total Other Loans [Member] | Personal Loans [Member]
Segment Reporting Information [Line Items]
Interest income	219	237	662	722
Operating Segments [Member] | Digital Banking [Member] | Total Other Loans [Member] | Other Loans [Member]
Segment Reporting Information [Line Items]
Interest income	30	27	85	78
Operating Segments [Member] | Digital Banking [Member] | Unallocated Financing Receivables | Other [Member]
Segment Reporting Information [Line Items]
Interest income	48	64	156	206
Operating Segments [Member] | Payment Services [Member]
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Interest expense	0	0	0	0
Net interest income	0	0	0	0
Provision for credit losses	0	0	0	0
Other income	(75)	78	833	320
Other expense	39	36	203	172
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	(114)	42	630	148
Operating Segments [Member] | Payment Services [Member] | Credit Card Loans [Member]
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Operating Segments [Member] | Payment Services [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Operating Segments [Member] | Payment Services [Member] | Total Other Loans [Member] | Personal Loans [Member]
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Operating Segments [Member] | Payment Services [Member] | Total Other Loans [Member] | Other Loans [Member]
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Operating Segments [Member] | Payment Services [Member] | Unallocated Financing Receivables | Other [Member]
Segment Reporting Information [Line Items]
Interest income	$ 0	$ 0	$ 0	$ 0

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Schedule of Revenue from Contracts with Customers Disaggregated by Business Segment) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net		$ 299	$ 238	$ 879	$ 691
Protection products revenue		43	44	129	135
Transaction processing revenue		58	50	167	143
Other income subject to ASC 606		18	17	47	59
Loan fee income		121	100	333	304
Unrealized (losses) gains on equity investments		(167)	0	562	0
Realized gains on equity investments		0	0	0	79
Total other income (loss) not subject to ASC 606		(46)	100	895	383
Total other income (loss) by operating segment		372	449	2,117	1,411
Customer rewards included in discount and interchange revenue		689	514	1,800	1,400
Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	299	238	879	691
Protection products revenue		43	44	129	135
Transaction processing revenue		58	50	167	143
Other income subject to ASC 606		18	17	47	59
Total other income subject to ASC 606	[2]	418	349	1,222	1,028
Operating Segments [Member] | Digital Banking [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		121	100	333	304
Unrealized (losses) gains on equity investments		0		0
Realized gains on equity investments					0
Total other income (loss) not subject to ASC 606		121	100	333	304
Total other income (loss) by operating segment		447	371	1,284	1,091
Operating Segments [Member] | Digital Banking [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	280	225	826	644
Protection products revenue		43	44	129	135
Transaction processing revenue		0	0	0	0
Other income subject to ASC 606		3	2	(4)	8
Total other income subject to ASC 606	[2]	326	271	951	787
Operating Segments [Member] | Payment Services [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		0	0	0	0
Unrealized (losses) gains on equity investments		(167)		562
Realized gains on equity investments					79
Total other income (loss) not subject to ASC 606		(167)	0	562	79
Total other income (loss) by operating segment		(75)	78	833	320
Operating Segments [Member] | Payment Services [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	19	13	53	47
Protection products revenue		0	0	0	0
Transaction processing revenue		58	50	167	143
Other income subject to ASC 606		15	15	51	51
Total other income subject to ASC 606	[2]	$ 92	$ 78	$ 271	$ 241
[1]	Net of rewards, including Cashback Bonus rewards, of $689 million and $514 million for the three months ended September 30, 2021 and 2020, respectively, and $1.8 billion and $1.4 billion for the nine months ended September 30, 2021 and 2020, respectively.
[2]	Excludes deposit product fees that are reported within net interest income, which were immaterial for the three and nine months ended September 30, 2021 and 2020.