Discover Financial Services (DFS) 10-Q 26 Oct 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 21, 2020
Document Information [Line Items]
Document type	10-Q
Document quarterly report	true
Document period end date	Sep. 30, 2020
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		306,496,332
Entity central index key	0001393612
Current fiscal year end date	--12-31
Document fiscal year focus	2020
Document fiscal period focus	Q3
Amendment flag	false

Condensed Consolidated Statemen

Condensed Consolidated Statements of Financial Condition - USD ($) $ in Millions		Sep. 30, 2020		Dec. 31, 2019
Assets
Cash and cash equivalents		$ 9,513		$ 6,924
Restricted cash		576		40
Other short-term investments	[1]	8,048		0
Investment securities (includes available-for-sale securities of $20,573 and $10,323 reported at fair value with associated amortized cost of $20,148 and $10,173 at September 30, 2020 and December 31, 2019, respectively)	[1]	20,854		10,595
Loan receivables
Loan receivables		88,660		95,894
Allowance for Credit Losses	[3]	(8,226)	[2]	(3,383)	[4]
Net loan receivables		80,434		92,511
Premises and equipment, net		1,121		1,057
Goodwill		255		255
Intangible assets, net		95		155
Other assets		3,453		2,459
Total assets		124,349		113,996
Deposits
Interest-bearing deposit accounts		76,938		71,955
Non-interest bearing deposit accounts		1,077		791
Total deposits		78,015		72,746
Short-term borrowings	[1]	10,700		0
Long-term borrowings		21,841		25,701
Accrued expenses and other liabilities		3,541		3,690
Total liabilities		114,097		102,137
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; 567,743,876 and 566,653,650 shares issued at September 30, 2020 and December 31, 2019, respectively		6		6
Preferred stock, par value $0.01 per share; 200,000,000 shares authorized; 10,700 and 5,700 shares issued and outstanding at September 30, 2020 and December 31, 2019, respectively		1,056		563
Additional paid-in capital		4,235		4,206
Retained earnings		19,292		21,290
Accumulated other comprehensive income (loss)		93		(119)
Treasury stock, at cost; 261,247,516 and 256,496,492 shares at September 30, 2020 and December 31, 2019, respectively		(14,430)		(14,087)
Total stockholders' equity		10,252		11,859
Total liabilities and stockholders' equity		124,349		113,996
Variable Interest Entity, Primary Beneficiary [Member]
Assets
Restricted cash		576		40
Loan receivables
Loan receivables		27,287		31,840
Allowance for Credit Losses	[5]	(1,964)		(1,179)
Other assets		6		5
Deposits
Long-term borrowings		11,425		14,284
Accrued expenses and other liabilities		$ 9		$ 15
[1]	Includes amounts related to a securities lending transaction in September 2020. See Note 2: Investments for additional information.
[2]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[3]	Prior to adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[4]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[5]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Available-for-sale investment securities, fair value	[1]	$ 20,573	$ 10,323
Available-for-sale investment securities, amortized cost	[1]	$ 20,148	$ 10,173
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		567,743,876	566,653,650
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		5,700	5,700
Treasury Stock, Shares		261,247,516	256,496,492
[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, 2020		Sep. 30, 2019		Sep. 30, 2020		Sep. 30, 2019
Interest income
Credit card loans	$ 2,171		$ 2,465		$ 6,760		$ 7,223
Other loans	446		472		1,369		1,389
Investment securities	58		53		171		120
Other interest income	6		50		35		222
Total interest income	2,681		3,040		8,335		8,954
Interest expense
Deposits	287		407		1,000		1,194
Short-term borrowings	3		0		3		0
Long-term borrowings	126		231		479		721
Total interest expense	416		638		1,482		1,915
Net interest income	2,265		2,402		6,853		7,039
Provision for credit losses	750	[1]	799	[2]	4,603	[3]	2,395	[2]
Net interest income after provision for credit losses	1,515		1,603		2,250		4,644
Other income
Discount and interchange revenue, net	238		255		691		785
Protection products revenue	44		48		135		146
Loan fee income	100		120		304		326
Transaction processing revenue	50		52		143		146
Gains on equity investments	0		0		79		0
Other income	17		23		59		73
Total other income	449		498		1,411		1,476
Other expense
Employee compensation and benefits	471		439		1,390		1,291
Marketing and business development	140		230		500		649
Information processing and communications	111		96		342		296
Professional fees	151		189		525		539
Premises and equipment	26		26		83		80
Other expense	106		127		401		354
Total other expense	1,005		1,107		3,241		3,209
Income before income taxes	959		994		420		2,911
Income tax expense	188		224		78		662
Net income	771		770		342		2,249
Net income allocated to common stockholders	$ 751		$ 749		$ 309		$ 2,203
Basic earnings per common share	$ 2.45		$ 2.36		$ 1		$ 6.83
Diluted earnings per common share	$ 2.45		$ 2.36		$ 1		$ 6.82
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[3]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 771	$ 770	$ 342	$ 2,249
Other comprehensive (loss) income, net of tax
Unrealized (losses) gains on available-for-sale investment securities, net of tax	(32)	17	208	119
Unrealized gains (losses) on cash flow hedges, net of tax	3	(8)	4	(38)
Unrealized pension and post-retirement plan gains, net of tax	0	0	0	1
Other comprehensive (loss) income	(29)	9	212	82
Comprehensive income	$ 742	$ 779	$ 554	$ 2,331

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock [Member]	Series C Preferred Stock [Member]Retained Earnings [Member]
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2018		6,000
Common stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2018			564,852,000
Stockholders' equity, balance at beginning of period at Dec. 31, 2018	$ 11,130	$ 563	$ 6	$ 4,130	$ 18,906	$ (156)	$ (12,319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,249				2,249
Other comprehensive income	82					82
Purchases of treasury stock	(1,367)						(1,367)
Common stock issued under employee benefit plans (in shares)			76,000
Common stock issued under employee benefit plans	6		$ 0	6
Common stock issued and stock-based compensation expense (in shares)			1,676,000
Common stock issued and stock-based compensation expense	52		$ 0	52
Dividends — common stock	(404)				(404)
Dividends — preferred stock	(31)							$ (31)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2019		6,000
Common stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2019			566,604,000
Stockholders' equity, balance at end of period at Sep. 30, 2019	11,717	$ 563	$ 6	4,188	20,720	(74)	(13,686)
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Jun. 30, 2019		6,000
Common stock, shares outstanding, balance at beginning of period (in shares) at Jun. 30, 2019			566,019,000
Stockholders' equity, balance at beginning of period at Jun. 30, 2019	11,493	$ 563	$ 6	4,167	20,107	(83)	(13,267)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	770				770
Other comprehensive income	9					9
Purchases of treasury stock	(419)						(419)
Common stock issued under employee benefit plans (in shares)			25,000
Common stock issued under employee benefit plans	3		$ 0	3
Common stock issued and stock-based compensation expense (in shares)			560,000
Common stock issued and stock-based compensation expense	18		$ 0	18
Dividends — common stock	(142)				(142)
Dividends — preferred stock	(15)				(15)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2019		6,000
Common stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2019			566,604,000
Stockholders' equity, balance at end of period at Sep. 30, 2019	$ 11,717	$ 563	$ 6	4,188	20,720	(74)	(13,686)
Preferred stock, shares outstanding, balance at beginning of period (in shares) at Dec. 31, 2019	5,700	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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	342				342
Other comprehensive income	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
Dividends — common stock	(407)				(407)
Dividends — preferred stock	(31)							(31)
Stock Issued During Period, Shares, New Issues		5,000
Stock Issued During Period, Value, New Issues	493	$ 493
Cumulative effect of ASU No. 2016-13 adoption	$ (1,902)				(1,902)
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2020	5,700	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 income	(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)
Stock Issued During Period, Value, New Issues	$ 0
Preferred stock, shares outstanding, balance at end of period (in shares) at Sep. 30, 2020	5,700	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)

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Stockholders' Equity [Abstract]
Dividends declared, common stock (dollars per share)	$ 0.44	$ 0.44	$ 1.32	$ 1.24
Dividends declared, preferred stock (dollars per share)	$ 2,750	$ 2,750	$ 5,500	$ 5,500

Condensed Consolidated Statem_7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019
Cash flows provided by operating activities
Net income	$ 342		$ 2,249
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	4,603	[1]	2,395	[2]
Deferred income taxes	(600)		(95)
Depreciation and amortization	362		315
Amortization of deferred revenues and accretion of accretable yield on acquired loans	(245)		(311)
Net (gain) loss on investments and other assets	(40)		30
Other, net	87		59
Changes in assets and liabilities:
Decrease (increase) in other assets	212		(33)
(Decrease) increase in accrued expenses and other liabilities	(158)		123
Net cash provided by operating activities	4,563		4,732
Cash flows used for investing activities
Purchases of other short-term investments	(8,046)		(1,000)
Maturities of available-for-sale investment securities	724		106
Purchases of available-for-sale investment securities	0		(7,183)
Maturities of held-to-maturity investment securities	34		21
Purchases of held-to-maturity investment securities	(44)		(54)
Net principal repaid (disbursed) on loans originated for investment	5,316		(3,848)
Proceeds from sale of other investments	94		0
Purchases of other investments	(54)		(49)
Purchases of premises and equipment	(206)		(212)
Net cash used for investing activities	(2,182)		(12,219)
Cash flows provided by (used for) financing activities
Proceeds from issuance of securitized debt	0		2,027
Maturities and repayment of securitized debt	(2,974)		(6,278)
Proceeds from issuance of other long-term borrowings	494		1,341
Maturities and repayment of other long-term borrowings	(1,754)		(86)
Proceeds from issuance of common stock	7		6
Purchases of treasury stock	(343)		(1,367)
Net increase in deposits	5,245		3,231
Proceeds from issuance of preferred stock	493		0
Dividends paid on common and preferred stock	(424)		(420)
Net cash provided by (used for) financing activities	744		(1,546)
Net increase (decrease) in cash, cash equivalents and restricted cash	3,125		(9,033)
Cash, cash equivalents and restricted cash, at beginning of period	6,964		15,145
Cash, cash equivalents and restricted cash, at end of period	10,089		6,112
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	9,513		6,075
Restricted cash	$ 576		$ 37
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2020
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 direct banking and payment services company. The Company is a bank holding company under the Bank Holding Company Act of 1956 as well as a financial holding company under the Gramm-Leach-Bliley Act and therefore is subject to oversight, regulation and examination by the Board of Governors of the Federal Reserve System (the "Federal Reserve"). The Company provides direct banking products and services and payment services through its subsidiaries. The Company offers its customers credit card loans, private student loans, personal loans, home equity loans and deposit products. The Company also operates the Discover Network, the PULSE network ("PULSE") and Diners Club International ("Diners Club"). 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, as well as merchant acceptance throughout the U.S. for debit card transactions. Diners Club is a global payments network of licensees, which are generally financial institutions, that issue Diners Club branded charge cards and/or provide card acceptance services. The Company's business activities are managed in two segments, Direct Banking and Payment Services, based on the products and services provided. For a detailed description of the operations of each segment, as well as the allocation conventions used in business segment reporting, see Note 17: Segment Disclosures. 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 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 2019 audited consolidated financial statements filed with the Company's annual report on Form 10-K for the year ended December 31, 2019. Recently Issued Accounting Pronouncements (Not Yet Adopted) In March 2020, the Financial Accounting Standards Board ("FASB") issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting . The ASU addresses operational challenges resulting from the discontinuation of the London Interbank Offered Rate (“LIBOR”) and other reference rates at the end of 2021. By providing optional practical expedients and exceptions to applying certain GAAP requirements, ASU No. 2020-04 provides temporary relief designed to ease the operational cost and burden of accounting for contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued as a result of reference rate reform. In general, the optional expedients and exceptions allow eligible contracts that are modified due to reference rate reform to be accounted for prospectively as a continuation of those contracts, permit companies to preserve hedge accounting for hedging relationships affected by reference rate reform and enable companies to make a one-time election to transfer or sell certain held-to-maturity debt securities indexed to LIBOR or another reference rate that is expected to be discontinued. The temporary expedients and exceptions are elective and do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, with the exception of hedging relationships existing as of that date for which certain optional expedients have been elected and are expected to be retained through the end of the hedging relationships. The ASU is effective upon issuance and management expects to apply the practical expedients provided by the ASU. As part of its overall evaluation of reference rate reform, management is still evaluating the impact that LIBOR replacement will have on the Company’s financial statements. Any such impacts will be prospective in nature, affecting net interest income and fair value estimates after the effective date of such rate replacement. Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The FASB subsequently issued several additional ASUs that clarify the scope and application of the new credit loss guidance. Topic 326 replaced the incurred loss model with the current expected credit loss ("CECL") approach. For loans carried at amortized cost, the allowance for credit losses is now based on management's current estimate of all anticipated credit losses over the remaining expected life of the loans. Upon the origination of a loan, the Company records its estimate of all expected credit losses on that loan through an immediate charge to earnings. Updates to that estimate each period are recorded through provision expense. The CECL estimate is based on historical experience, current conditions and reasonable and supportable forecasts. As compared to prior GAAP, the CECL approach increases the Company's allowance for credit losses on loan receivables as a result of: (1) recording reserves for expected losses, not simply those deemed to be already incurred, (2) extending the loss estimate period over the entire life of the loan and (3) presenting the credit loss component of the purchased credit-impaired ("PCI") loan portfolio in the allowance for credit losses rather than embedding it within the loan carrying value. The allowance for credit losses on all loans carried at amortized cost, including loans previously referred to as PCI loans and loans modified in a troubled debt restructuring ("TDR") are measured under the CECL approach. Previous specialized measurement guidance for PCI loans, which are now referred to as purchased credit-deteriorated ("PCD"), and TDRs was eliminated, although certain separate disclosure guidance was retained. Measurement of credit impairment of available-for-sale debt securities generally remains unchanged under the new rules, but any credit impairment is recorded through an allowance, rather than a direct write-down of the security. The Company invests in U.S. Treasury and residential mortgage-backed securities issued by government agencies, which have long histories with no credit losses and are explicitly or implicitly guaranteed by the U.S. 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. The ASU became effective for the Company on January 1, 2020, and required modified-retrospective application, meaning a cumulative-effect adjustment was recorded as of the effective date without adjusting comparative prior periods. This cumulative-effect adjustment did not reflect the economic disruption resulting from the coronavirus disease 2019 ("COVID-19") since the global disruption occurred subsequent to January 1, 2020. As a result of adoption, the Company recorded: • A $2.5 billion increase to the allowance for credit losses on loan receivables primarily representing the adjustment for recording reserves for expected losses, not simply those deemed to be already incurred, and extending the loss estimate period over the entire life of the loan; • A $0.6 billion increase to other assets related to deferred tax assets on the larger allowance for credit losses; • An offsetting $1.9 billion decrease, net of tax, to the opening balance of retained earnings; and • Immaterial adjustments to the following: ◦ The carrying value of PCD loans and related accrued interest reflected in other assets; and ◦ Accrued expenses and other liabilities to record reserves for unfunded commitments. As required by the ASU, financial statement results and balances prior to January 1, 2020, have not been retrospectively adjusted to reflect the amendments in ASU No. 2016-13. Therefore, current period results and balances are not comparable to prior period amounts, particularly with regard to the provision and allowance for credit losses (and their related subtotals).

Investments

Investments	9 Months Ended
	Sep. 30, 2020
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, U.S. Treasury bills (1) $ 2,139 $ — U.S. Treasury bills - Pledged 5,909 — Total other short-term investments $ 8,048 $ — U.S. Treasury securities $ 3,930 $ 9,785 U.S. Treasury securities - Pledged (2) 5,618 121 Total U.S. Treasury securities 9,548 9,906 Residential mortgage-backed securities - Agency (3) 11,306 689 Total investment securities $ 20,854 $ 10,595 (1) Includes U.S. Treasury bills with maturity dates greater than 90 days but less than one year at the time of acquisition. (2) As of September 30, 2020 and December 31, 2019, includes $135 million and $121 million, respectively, of U.S. Treasury securities pledged as swap collateral other than amounts associated with the September 2020 securities lending transaction. (3) Consists of residential mortgage-backed securities issued by Fannie Mae, Freddie Mac and Ginnie Mae. In September 2020, the Company, in an initiative for one of Discover Bank's lending businesses, entered into a short-term securities lending transaction with a counterparty. Discover Bank lent $11.4 billion of U.S. Treasury bills and securities and received agency pass-through residential mortgage-backed securities (“RMBS”) as collateral from the borrower. Throughout the term of the transaction, the counterparty is required to adjust the RMBS collateral daily to ensure it is maintained at a fair value equal to $11.6 billion, which is 102% of the value of the U.S. Treasury bills and securities lent. Of the $11.6 billion of RMBS, the Company has the right to sell or repledge $10.7 billion. As these investments are not held for trading purposes, they are designated as available-for-sale and recorded in investment securities on the condensed consolidated statements of financial position. As of September 30, 2020, the RMBS had a carrying value and fair value of $10.7 billion. No portion of the collateral was sold or repledged as of September 30, 2020. To reflect the obligation to return the RMBS collateral, the Company recognized $10.7 billion in short-term borrowings, which are recorded within the condensed consolidated statements of financial condition as of September 30, 2020. The Company will release the $11.6 billion of RMBS, and receive the U.S. Treasury bills and securities lent, when the transaction matures in November 2020. The U.S. Treasury bills and securities are recorded as other short-term investments and investment securities on the Company's condensed consolidated statement of financial position, respectively. As the lender in the transaction, the Company earns a securities lending fee. This securities lending fee, as well as the interest income and interest expense associated with the transaction, were immaterial for the three and nine months ended September 30, 2020. 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, 2020 Available-for-Sale Investment Securities (1) U.S. Treasury securities $ 9,134 $ 414 $ — $ 9,548 Residential mortgage-backed securities - Agency 11,014 11 — 11,025 Total available-for-sale investment securities $ 20,148 $ 425 $ — $ 20,573 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 281 $ 9 $ — $ 290 Total held-to-maturity investment securities $ 281 $ 9 $ — $ 290 At December 31, 2019 Available-for-Sale Investment Securities (1) U.S. Treasury securities $ 9,759 $ 155 $ (8) $ 9,906 Residential mortgage-backed securities - Agency 414 3 — 417 Total available-for-sale investment securities $ 10,173 $ 158 $ (8) $ 10,323 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 272 $ 3 $ (1) $ 274 Total held-to-maturity investment securities $ 272 $ 3 $ (1) $ 274 (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 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 U.S. Treasury and residential mortgage-backed securities issued by government agencies, which have long histories with no credit losses and are explicitly or implicitly guaranteed by the U.S. 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. The following table provides information about available-for-sale investment securities with aggregate gross unrealized losses and the length of time that individual investment securities have been in a continuous unrealized loss position (dollars in millions): Number of Securities in a Loss Position Less than 12 months More than 12 months Fair Unrealized Fair Unrealized At December 31, 2019 Available-for-Sale Investment Securities U.S. Treasury securities 11 $ 1,402 $ (8) $ — $ — There were no proceeds from sales or recognized gains and losses on available-for-sale securities during the three or nine months ended September 30, 2020 and 2019. 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, 2020 and 2019. 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, 2020 One Year After One After Five After Ten Total Available-for-Sale Investment Securities—Amortized Cost U.S. Treasury securities $ 1,880 $ 7,254 $ — $ — $ 9,134 Residential mortgage-backed securities - Agency (1) — 54 291 10,669 11,014 Total available-for-sale investment securities $ 1,880 $ 7,308 $ 291 $ 10,669 $ 20,148 Held-to-Maturity Investment Securities—Amortized Cost Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 281 $ 281 Total held-to-maturity investment securities $ — $ — $ — $ 281 $ 281 Available-for-Sale Investment Securities—Fair Values U.S. Treasury securities $ 1,900 $ 7,648 $ — $ — $ 9,548 Residential mortgage-backed securities - Agency (1) — 56 300 10,669 11,025 Total available-for-sale investment securities $ 1,900 $ 7,704 $ 300 $ 10,669 $ 20,573 Held-to-Maturity Investment Securities—Fair Values Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 290 $ 290 Total held-to-maturity investment securities $ — $ — $ — $ 290 $ 290 (1) Maturities of residential mortgage-backed securities 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, as well as 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 the receipt of tax credits allocated to the affordable housing projects and the community revitalization projects. These investments are not consolidated as the Company does not have a controlling financial interest in the investee entities. As of September 30, 2020 and December 31, 2019, the Company had outstanding investments in these entities of $323 million and $336 million, respectively, and related contingent liabilities of $61 million and $74 million, respectively. Of the above outstanding equity investments, the Company had $292 million and $298 million of investments related to affordable housing projects as of September 30, 2020 and December 31, 2019, respectively, which had $45 million and $59 million related contingent liabilities, 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, 2020 and December 31, 2019, the carrying value of these investments, which is recorded within other assets, was $35 million and $42 million, respectively.

Loan Receivables

Loan Receivables	9 Months Ended
	Sep. 30, 2020
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) $ 69,656 $ 77,181 Other loans (3) Private student loans (4) 10,016 9,653 Personal loans 7,211 7,687 Other 1,777 1,373 Total other loans 19,004 18,713 Total loan receivables 88,660 95,894 Allowance for credit losses (5) (8,226) (3,383) Net loan receivables $ 80,434 $ 92,511 (1) Amounts include carrying values of $15.4 billion and $18.9 billion underlying investors' interest in trust debt at September 30, 2020 and December 31, 2019, respectively, and $11.6 billion and $12.7 billion in seller's interest at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and 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 $380 million and $471 million at September 30, 2020 and December 31, 2019, 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 $527 million, $47 million and $6 million, respectively, at September 30, 2020 and $461 million, $53 million and $4 million, respectively, at December 31, 2019. (4) Amounts include carrying values of $261 million and $292 million in loans pledged as collateral against the note issued from a student loan securitization trust at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information. (5) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. 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 as well as information from credit bureaus, such as FICO or other credit scores, relating to the customer's broader credit performance. Key credit quality indicators that are actively monitored for credit card, private student and personal loans include FICO scores and delinquency status. 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 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, 2020 December 31, 2019 660 and Above Less than 660 660 and Above Less than 660 $ % $ % $ % $ % Credit card loans (1) $ 57,148 82 % $ 12,508 18 % $ 61,997 80 % $ 15,184 20 % Private student loans by origination year (2)(3) 2020 $ 983 97 % $ 29 3 % 2019 1,690 97 % 57 3 % $ 1,176 93 % $ 92 7 % 2018 1,399 96 % 60 4 % 1,518 95 % 79 5 % 2017 1,076 95 % 57 5 % 1,198 95 % 69 5 % 2016 817 94 % 48 6 % 934 94 % 58 6 % Prior 3,586 94 % 214 6 % 4,229 93 % 300 7 % Total private student loans $ 9,551 95 % $ 465 5 % $ 9,055 94 % $ 598 6 % Personal loans by origination year 2020 $ 2,175 99 % $ 15 1 % 2019 2,506 97 % 89 3 % $ 3,529 98 % $ 62 2 % 2018 1,221 92 % 101 8 % 1,941 93 % 140 7 % 2017 680 89 % 81 11 % 1,167 90 % 136 10 % 2016 242 88 % 34 12 % 475 88 % 65 12 % Prior 55 82 % 12 18 % 145 84 % 27 16 % Total personal loans $ 6,879 95 % $ 332 5 % $ 7,257 94 % $ 430 6 % (1) Amounts include $1.0 billion and $956 million of revolving line-of-credit arrangements that were converted to term loans as a result of a TDR program as of September 30, 2020 and December 31, 2019, respectively. (2) A majority of student loans 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, 2020 December 31, 2019 30-89 Days 90 or Total Past 30-89 Days 90 or Total Past Credit card loans $ 678 $ 650 $ 1,328 $ 999 $ 1,020 $ 2,019 Private student loans by origination year (1)(2) 2020 $ — $ — $ — 2019 3 — 3 $ 1 $ — $ 1 2018 11 3 14 4 1 5 2017 13 4 17 11 2 13 2016 14 4 18 14 5 19 Prior 76 21 97 106 37 143 Total private student loans $ 117 $ 32 $ 149 $ 136 $ 45 $ 181 Personal loans by origination year 2020 $ 4 $ 1 $ 5 2019 19 7 26 $ 11 $ 3 $ 14 2018 17 7 24 27 11 38 2017 11 5 16 22 10 32 2016 4 2 6 10 5 15 Prior 1 1 2 4 2 6 Total personal loans $ 56 $ 23 $ 79 $ 74 $ 31 $ 105 (1) 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. (2) Includes PCD loans for all periods presented. In response to the pandemic, the Company expanded borrower relief offerings to include Skip-a-Pay (payment deferral) programs in addition to other modification programs already available. While the Company continues to support and provide assistance to all customers impacted by COVID-19, the Company is no longer offering new enrollments in the Skip-a-Pay (payment deferral) programs as of August 31, 2020. The Skip-a-Pay program allowed customers on a monthly or other periodic basis to request approval to skip their payment(s) for that month or period. The current accounts that used these modifications did not advance to delinquency and delinquent accounts enrolled in these programs did not advance to the next delinquency cycle or to charge-off. These accounts were generally excluded from TDR status either because the concessions were insignificant or they qualified for exemption pursuant to the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act"). In addition to the Skip-a-Pay (payment deferral) programs, the Company has other modification programs that customers have utilized during the period. Due to provisions in the CARES Act, some accounts in these programs do not constitute TDRs. Allowance for Credit Losses A detailed description of the Company's allowance for credit losses policy can be found under the sub-heading "— Significant Loan Receivables Accounting Policies — Allowance for Credit Losses" below. The following tables provide changes in the Company's allowance for credit losses (dollars in millions): For the Three Months Ended September 30, 2020 Credit Card Loans Student Loans Personal Loans Other Loans Total 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 Three Months Ended September 30, 2019 Credit Card Loans Student Loans Personal Loans Other Loans Total Balance at June 30, 2019 (2) $ 2,691 $ 167 $ 338 $ 6 $ 3,202 Additions Provision for credit losses (2) 719 (6) 86 — 799 Deductions Charge-offs (784) (17) (89) (1) (891) Recoveries 173 3 13 — 189 Net charge-offs (3) (611) (14) (76) (1) (702) Balance at September 30, 2019 (2) $ 2,799 $ 147 $ 348 $ 5 $ 3,299 For the Nine Months Ended September 30, 2020 Credit Card Loans Student Loans Personal Loans Other Loans Total Balance at December 31, 2019 (2) $ 2,883 $ 148 $ 348 $ 4 $ 3,383 Cumulative effect of ASU No. 2016-13 adoption (4) 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 For the Nine Months Ended September 30, 2019 Credit Card Loans Student Loans Personal Loans Other Loans Total Balance at December 31, 2018 (2) $ 2,528 $ 169 $ 338 $ 6 $ 3,041 Additions Provision for credit losses (2) 2,121 24 250 — 2,395 Deductions Charge-offs (2,347) (54) (274) (1) (2,676) Recoveries 497 10 34 — 541 Net charge-offs (3) (1,850) (44) (240) (1) (2,135) Other (5) — (2) — — (2) Balance at September 30, 2019 (2) $ 2,799 $ 147 $ 348 $ 5 $ 3,299 (1) Excludes a $40 million build and $17 million build of the liability for expected credit losses on unfunded commitments for the three months and nine months ended September 30, 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 adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. (3) Prior to adoption of ASU No. 2016-13 on January 1, 2020, net charge-offs on PCD loans generally did not result in a charge to earnings. (4) Represents the adjustment to allowance for credit losses as a result of adoption of ASU No. 2016-13 on January 1, 2020. (5) Net change in reserves on PCD pools having no remaining non-accretable difference (prior to adoption of ASU No. 2016-13 on January 1, 2020). The allowance for credit losses was $8.2 billion at September 30, 2020, which is essentially flat compared to the amount of the allowance for credit losses at June 30, 2020. In estimating the allowance at September 30, 2020, the Company used a macroeconomic forecast that projected slight improvement from the prior quarter, including a peak unemployment rate of 11%, which remained flat through the end of 2020 and recovers slowly over the next few years. The Company also considered the uncertainties associated with some of the assumptions used in that macroeconomic forecast, including the amount and timing of additional government stimulus. Furthermore, the estimate contemplated the impact of previous government stimulus programs and other company-initiated loan modification programs on borrower payment trends. The impact of COVID-19 on the economy has continued to cause uncertainty in assumptions surrounding factors such as length and depth of economic stresses and longer term impacts on borrower behavior, which has required significant management judgment in estimating the allowance for credit losses. Company-initiated loan modification programs include those offered specifically in response to COVID-19 as well as existing programs also offered to customers experiencing difficulty making their payments. In addition to Skip-a-Pay (payment deferral) 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 accounts using these modifications are generally excluded from TDR status either because the concessions are insignificant or they qualify for exemption under the CARES Act. All modifications are considered as part of the process for determining the allowance for credit losses. The allowance for credit losses was $8.2 billion at September 30, 2020, which reflects a $4.8 billion build over the amount of the allowance for credit losses at December 31, 2019. The allowance build across all loan products was due to (I) a $2.5 billion cumulative-effect adjustment for the adoption of CECL on January 1, 2020, and (II) a $2.3 billion build that primarily reflects an economic outlook that included the COVID-19 pandemic and resulting economic stress. The forecast period management deemed to be reasonable and supportable was 18 months for all periods since the adoption of CECL except for the estimate as of March 31, 2020. The decrease to 12 months as of March 31, 2020, was due to the uncertainty caused by the rapidly changing economic environment resulting from the COVID-19 pandemic. The return to an 18-month reasonable and supportable forecast period was based on the view that the present macroeconomic conditions will last for a longer period than previously expected. The reversion period was 12 months for all quarters since the adoption of CECL. During the first quarter of 2020, a straight-line method was used to revert to appropriate historical information. In the second quarter of 2020, the high degree of economic stress led the Company to apply a weighted reversion method for credit card loans that puts more emphasis on the loss forecast model rather than lower historical losses. For similar reasons, the Company determined it was appropriate to apply a weighted reversion method for all loans in the third quarter. The net charge-offs on credit card loans for the three months ended September 30, 2020, was relatively flat when compared to same period in 2019. The increase in net charge-offs on credit card loans for the nine months ended September 30, 2020, when compared to the same period in 2019 was due to the seasoning of recent years' loan growth. 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, 2020 2019 2020 2019 Interest and fees accrued subsequently charged off, net of recoveries (recorded as a reduction of interest income) $ 114 $ 127 $ 393 $ 382 Fees accrued subsequently charged off, net of recoveries (recorded as a reduction to other income) $ 27 $ 29 $ 95 $ 90 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 by each class of loan receivables (dollars in millions): 30-89 Days 90 or Total Past 90 or Total Non-accruing (1) At September 30, 2020 Credit card loans $ 678 $ 650 $ 1,328 $ 604 $ 196 Other loans Private student loans (2) 117 32 149 31 12 Personal loans 56 23 79 22 9 Other 8 3 11 — 11 Total other loans 181 58 239 53 32 Total loan receivables $ 859 $ 708 $ 1,567 $ 657 $ 228 At December 31, 2019 Credit card loans $ 999 $ 1,020 $ 2,019 $ 940 $ 237 Other loans Private student loans (2) 136 45 181 45 11 Personal loans 74 31 105 29 12 Other 5 2 7 — 6 Total other loans 215 78 293 74 29 Total loan receivables $ 1,214 $ 1,098 $ 2,312 $ 1,014 $ 266 (1) The Company estimates that the gross interest income that would have been recorded in accordance with the original terms of non-accruing credit card loans was $7 million and $12 million for the three months ended September 30, 2020 and 2019, respectively, and $25 million and $34 million for the nine months ended September 30, 2020 and 2019, respectively. The Company does not separately track the amount of gross interest income that would have been recorded in accordance with the original terms of loans. This amount was estimated based on customers' current balances and most recent interest rates. (2) Includes PCD loans for all periods presented. Troubled Debt Restructurings The Company has internal loan modification programs that provide relief to credit card, 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. New programs are continually evaluated to determine which of them meet the definition of a TDR, including programs provided to customers for temporary relief due to the economic impacts of the COVID-19 outbreak that may be subject to regulatory exclusion from TDR status. 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. For all temporary modification programs, including those created specifically in response to COVID-19, the accounts are reviewed for exclusion from being reported as a TDR in accordance with the CARES Act. To the extent the accounts do not meet the requirements for exclusion, temporary and permanent modifications on credit card and personal loans, as well as temporary modifications on student loans and certain grants of student loan forbearance, result in the loans being classified as TDRs. In addition, loans that defaulted (see table on loans that defaulted from a TDR program that follows) or graduated from modification programs or forbearance continue to be classified as TDRs, except as noted below. 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 loans are generally suspended while in the program and if certain criteria are met, may be reinstated following completion of the program. Beginning in 2020, credit card accounts of borrowers that have previously participated in a temporary interest rate reduction program and that 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 structure of the loan to a fixed payment loan with a maturity no longer than 60 months and reducing the interest rate on the loan. The permanent modification program does not normally 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 but continue to be subject to the original minimum payment terms and do not normally include waiver of unpaid principal, interest or fees. These loans remain in the population of TDRs until they are paid off or charged off. At September 30, 2020 and December 31, 2019, there were $5.3 billion and $5.6 billion, respectively, of private student loans in repayment and $64 million and $46 million, respectively, in forbearance. To assist student loan borrowers who are experiencing temporary financial difficulties but are willing to resume making payments, the Company may offer hardship forbearance or programs that include payment deferral, temporary payment reduction, 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 credit quality of the borrower using FICO scores. For personal loan customers, in certain situations the Company offers various payment programs, including temporary and permanent programs. The temporary programs normally consist of a reduction of the minimum payment for a period of no longer than 12 months with the option of a final balloon payment required at the end of the loan term or an extension of the maturity date with the total term not exceeding nine years. Further, in certain circumstances the interest rate on the loan is reduced. The permanent programs involve changing the terms of the loan in order to pay off the outstanding balance over a longer term and in certain circumstances reducing the interest rate on the loan. Similar to the temporary programs, the total term 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. Borrower performance after using payment programs or forbearance is monitored and 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 as a means to provide relief to customers experiencing temporary financial difficulties and, as a result, expects to have additional loans classified as TDRs in the future. In order 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, 2020 and 2019, the Company quantified the amount by which interest and fees were reduced during the periods. During the three months ended September 30, 2020 and 2019, the Company forgave approximately $13 million and $19 million, respectively, of interest and fees as a result of accounts entering into a credit card loan TDR program. During the nine months ended September 30, 2020 and 2019, the Company forgave approximately $52 million and $53 million, respectively, of interest and fees as a result of 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. TDR program balances and number of accounts have been favorably impacted by customer usage of modifications that were subject to TDR exclusion in accordance with the CARES Act and are lower than comparative periods as a result. 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, 2020 2019 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 20,779 $ 150 97,046 $ 623 Private student loans 118 $ 2 1,692 $ 31 Personal loans 2,505 $ 33 2,859 $ 39 For the Nine Months Ended September 30, 2020 2019 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 130,869 $ 875 273,970 $ 1,766 Private student loans 1,767 $ 32 4,978 $ 92 Personal loans 6,315 $ 83 8,129 $ 110 (1) Accounts that entered a credit card TDR program include $143 million and $173 million that were converted from revolving line-of-credit arrangements to term loans during the three months ended September 30, 2020 and 2019, respectively, and $529 million and $336 million for the nine months ended September 30, 2020 and 2019, respectively. The following table presents the carrying value of loans that experienced a payment 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, 2020 2019 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) 8,983 $ 52 19,108 $ 109 Private student loans (3) 272 $ 6 396 $ 8 Personal loans (2) 624 $ 9 1,131 $ 15 For the Nine Months Ended September 30, 2020 2019 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) 41,285 $ 235 50,980 $ 294 Private student loans (3) 876 $ 18 966 $ 19 Personal loans (2) 2,446 $ 36 2,925 $ 42 (1) Terms revert back to the pre-modification terms for customers who default from a temporary program and charging privileges remain suspended in most cases. (2) For credit card loans and personal loans, a customer defaults from a TDR program after two consecutive missed payments. The outstanding balance upon default is generally the loan balance at the end of the month prior to default. (3) For student loans, defaults have been defined as loans that 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, 2020 and 2019, approximately 65% and 37%, respectively, and for the nine months ended September 30, 2020 and 2019, approximately 52% and 38%, respectively, of the total balances were charged off at the end of the month in which they defaulted from a TDR program. Significant Loan Receivables Accounting Policies With the adoption of ASU No. 2016-13 on January 1, 2020, certain significant accounting policies have changed since disclosed in Note 2: Summary of Significant Accounting Policies to the consolidated financial statements of the Company's annual report on Form 10-K for the year ended December 31, 2019. Refer to Note 1: Background and Basis of Presentation for details on adoption of the standard. Impacts on all significant loan receivables accounting policies are summarized as follows: • The loan receivables policy was updated to reflect the removal of PCI loans as a separate loan portfolio segment. • The relevance of the PCI loan policy was eliminated by CECL and therefore it was removed as a significant accounting policy. • The delinquent loans and charge-offs policy did not change. • The allowance for credit losses policy was updated to reflect the CECL approach for estimating credit losses. • The loan interest and fee income policy, which includes certain accounting policy elections related to accrued interest, did not materially change. The policies below represent those with significant updates resulting from adoption of ASU 2016-13 and are reflective of those updates. Policies that did not materially change can be found at Note 2: Summary of Significant Accounting Policies to the consolidated financial statements of the Company's annual report on Form 10-K for the year ended December 31, 2019. Loan Receivables Loan receivables consist of credit card receivables and other loan receivables. Loan receivables also include unamortized net deferred loan origination fees and costs. Credit card loan receivables are reported at their principal amounts outstanding and include uncollected billed interest and fees and are reduced for unearned revenue related to balance transfer fees. Other loan receivables consist of student loans, personal loans and other loans and are reported at their principal amounts outstanding. For student loans, principal amounts outstanding also include accrued interest that has been capitalized. The Company's loan receivables are deemed to be held for investment at origination or acquisition because management has the intent and ability to hold them for the foreseeable future. Cash flows associated with loans originated or acquired for investment are classified as cash flows from investing activities, regardless of a subsequent change in intent. Allowance for Credit Losses The Company maintains an allowance for credit losses at a level that is appropriate to absorb credit losses anticipated over the remaining expected life of loan receivables as of the balance sheet date. The estimate of expected credit losses considers uncollectible principal, interest and fees associated with the Company's loan receivables existing as of the balance sheet date. Additionally, the estimate includes expected recoveries of amounts that were either previously charged off or are expected to be charged off. The allowance is evaluated quarterly for appropriateness and is maintained through an adjustment to the provision for credit losses. Charge-offs of principal amounts of loans outstanding are deducted from the allowance and subsequent recoveries of such amounts increase the allowance. Charge-offs of loan balances representing unpaid interest and fees result in a reversal of interest and fee income, respectively, which is effectively a reclassification of the provision for credit losses. The Company calculates its allowance for credit losses by estimating expected credit losses separately for classes of the loan portfolio with similar risk characteristics, which results in segmenting the portfolio by loan product type. The allowance for credit losses for each loan product type is based on: 1) a reasonable and supportable forecast period, 2) a reversion period and 3) a post-reversion period based on historical information covering the remaining life of the loan, all of which is netted with expected recoveries. The lengths of the reasonable and supportable forecast and reversion periods can vary and are subject to a quarterly assessment that considers the economic outlook and level of variability among macroeconomic forecasts. Generally, a straight-line method is used to revert from the reasonable and supportable forecast period to the post-reversion period, but in certain stressed scenarios, a weighted approach may be deemed more appropriate. Several analyses are used to help estimate credit losses anticipated over the remaining expected life of loan receivables as of the balance sheet date. The Company's estimation process includes models that predict customer losses based on risk characteristics and portfolio attributes, macroeconomic variables, and historical data and analysis. There is a significant amount of judgment applied in selecting inputs and analyzing the results produced by the models to determine the allowance. For credit card loans, the Company uses a modeling framework that includes the following components for estimating expected credit losses: • Probability of default: this model estimates the probability of charge-off at different points in time over the life of each loan. • Exposure at default: this model estimates the portion of the balance sheet date balance remaining at any given time of charge-off for each loan. Given that there is no stated life of a receivable balance on a revolving credit card account, the Company applies a percentage of expected payments to estimate the portion of the balance that would remain at the time of charge-off. • Loss given default: this model estimates the percentage of exposure (i.e. net loss) at time of charge-off that cannot be recovered, with the offsetting forecast recoveries being the driver of this estimate. • Recoveries from previously charged-off accounts are estimated separately and are netted as part of the aggregation of all of the components of the card loss modeling framework. For student loans and personal loans, the Company uses vintage-based models that estimate expected credit losses over the life of the loan, net of recovery estimates, impacted mainly by time elapsed since origination, credit quality of origination vintages and macroeconomic forecasts. The models described above for credit card, student and personal loans are developed utilizing historical data and applicable macroeconomic variable inputs based on statistical analysis and behavioral relationships with credit performance. Expected recoveries from loans charged off as of the balance sheet date are modeled separately and included in the allowance estimate. The Company leverages these models and recent macroeconomic forecasts for the portion of the estimate associated with the reasonable and supportable forecast period. To estimate expected credit losses for the remainder of the life of the credit card loans, the Company reverts to historical experience of credit card loans with characteristics similar to those as of the balance sheet date and observed over various phases of a credit cycle. To estimate expected credit losses for the re

Credit Card and Student Loan Se

Credit Card and Student Loan Securitization Activities	9 Months Ended
	Sep. 30, 2020
Variable Interest Entities Disclosure [Abstract]
Credit Card and Student Loan Securitization Activities	Credit Card and 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 of the Company's annual report on Form 10-K for the year ended December 31, 2019. 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. In order 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. The subordinated classes are held by wholly-owned subsidiaries of Discover Bank. The Company is exposed to credit-related risk of loss associated with trust assets as of the balance sheet date through the retention of these subordinated interests. The estimated loss is included in the allowance for credit losses estimate. The Company's retained interests in the assets of the trusts, consisting of investments in DCENT notes held by subsidiaries of Discover Bank, constitute intercompany positions, which 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 trusts' creditors. Further, the transferred credit card loan receivables are owned by the trust and are not available to third-party creditors of the Company. The trusts have ownership of cash balances, the amounts of which are reported in restricted cash. With the exception of the seller's interest in trust receivables, the Company's interests in trust assets are generally subordinate to the interests of third-party investors and, as such, may not be realized by the Company if needed to absorb deficiencies in cash flows that are allocated to the investors in the trusts' debt. 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 $ 567 $ 28 Investors' interests held by third-party investors 11,150 14,100 Investors' interests held by wholly-owned subsidiaries of Discover Bank 4,249 4,796 Seller's interest 11,627 12,652 Loan receivables (1) 27,026 31,548 Allowance for credit losses allocated to securitized loan receivables (1)(2) (1,964) (1,179) Net loan receivables 25,062 30,369 Other 4 5 Carrying value of assets of consolidated variable interest entities $ 25,633 $ 30,402 (1) The Company maintains its allowance for credit losses at an amount sufficient to absorb expected losses inherent in all loan receivables, which includes all loan receivables in the trusts. Therefore, credit risk associated with the transferred receivables is fully reflected on the Company's balance sheet in accordance with GAAP. (2) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. 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, there are certain features or triggering events that could 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, 2020, 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. Student Loan Securitization Activities Student loan trust receivables are reported in loan receivables and the related debt issued by the trusts is reported in long-term borrowings. The assets of the trusts 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. With the exception of the trusts' restricted assets, the trusts and investors have no recourse to the Company's other assets or the Company's general credit for a shortage in cash flows. Securities issued to investors are outstanding from only one of the two remaining student loan securitization trusts. Principal payments on the long-term secured borrowings are made as cash is collected on the underlying loans that are used as 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 own and service the accounts that generate the 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 $ 12 Student loan receivables 261 292 Carrying value of assets of consolidated variable interest entities $ 270 $ 304

Intangible Assets (Notes)

Intangible Assets (Notes)	9 Months Ended
	Sep. 30, 2020
Intangible Assets [Abstract]
Intangible Assets	Intangible Assets In connection with the preparation of the financial statements for the second quarter report on Form 10-Q, the Company identified a triggering event due to changes in the international travel and entertainment businesses and a declining revenue outlook for the foreseeable future resulting from COVID-19. As a result, during the second quarter the Company conducted an interim impairment test on its Diners Club trade names and international transaction processing rights non-amortizable intangible assets. The valuation of the trade names and international transaction processing rights was based on a discounted cash flow method, consistent with the methodology used for annual impairment testing. As a result of this analysis, the Company made the determination that the trade names and international transaction processing rights were impaired and recognized a charge, during the second quarter, in its Payment Services segment of $36 million and $23 million, respectively. The impairment was recorded in other expense. As of September 30, 2020, no additional material impairments have been recorded and annual impairment testing will resume on October 1, 2020.

Deposits

Deposits	9 Months Ended
	Sep. 30, 2020
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 certificates of deposit and checking accounts, while 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 $ 21,071 $ 25,113 Certificates of deposit in amounts $100,000 or greater (1) 9,771 9,268 Savings deposits, including money market deposit accounts 46,096 37,574 Total interest-bearing deposits $ 76,938 $ 71,955 (1) Includes $2.8 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, 2020 and December 31, 2019, 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 $ 1,734 Over three months through six months 2,375 Over six months through twelve months 3,166 Over twelve months 2,496 Total $ 9,771 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, 2020 $ 4,861 2021 15,825 2022 4,353 2023 2,214 2024 1,357 Thereafter 2,232 Total $ 30,842

Long-Term Borrowings

Long-Term Borrowings	9 Months Ended
	Sep. 30, 2020
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, 2020 December 31, 2019 Maturity Interest Weighted-Average Interest Rate Outstanding Amount Outstanding Amount Securitized Debt Fixed-rate asset-backed securities (1) 2020-2024 1.85%-3.32% 2.70% $ 6,621 $ 8,609 Floating-rate asset-backed securities (2) 2021-2024 0.38%-0.75% 0.55% 4,668 5,515 Total Discover Card Master Trust I and Discover Card Execution Note Trust 11,289 14,124 Floating-rate asset-backed security (3)(4) 2031 4.25% 4.25% 136 160 Total student loan securitization trust 136 160 Total long-term borrowings - owed to securitization investors 11,425 14,284 Discover Financial Services (Parent Company) Fixed-rate senior notes 2022-2027 3.75%-5.20% 4.16% 3,327 3,296 Fixed-rate retail notes 2021-2031 2.85%-4.60% 3.73% 336 340 Discover Bank Fixed-rate senior bank notes (1) 2021-2030 2.45%-4.65% 3.89% 6,236 6,785 Fixed-rate subordinated bank notes 2028-2028 4.68%-4.68% 4.68% 517 996 Total long-term borrowings $ 21,841 $ 25,701 (1) The Company uses interest rate swaps to hedge portions of these long-term borrowings against changes in fair value attributable to changes in LIBOR or Overnight Index Swap ("OIS") Rate. Use of these interest rate swaps impacts carrying value of the debt. See Note 16: Derivatives and Hedging Activities. (2) Discover Card Execution Note Trust floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month LIBOR + 23 to 60 basis points as of September 30, 2020. (3) The 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, 2020. (4) Repayment of this debt is dependent upon the timing of principal and interest payments on the underlying student loans. The date shown represents 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, 2020 2020 $ 550 2021 4,232 2022 5,204 2023 3,411 2024 2,630 Thereafter 5,814 Total $ 21,841 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, 2020, the total commitment of secured credit facilities through private providers was $6.0 billion, none of which was drawn as of September 30, 2020. Access to the unused portions of the secured credit facilities is subject to the terms of the agreements with each of the providers, which have various expirations in calendar year 2022. Borrowings outstanding under each facility bear interest at a margin above LIBOR or the asset-backed commercial paper costs of each individual conduit 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, 2020
Equity [Abstract]
Preferred Stock	Preferred StockOn June 22, 2020, the Company issued and sold 5,000 shares of 6.125% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series D (the “preferred stock”), with a par value of $0.01 per share. Each share of preferred stock has a liquidation preference of $1,000 and is represented by 100 depositary shares. Proceeds received from the preferred stock issuance, net of underwriting discount and expenses, totaled approximately $493 million. The preferred stock is redeemable at the Company’s option, subject to regulatory approval, either (1) 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 preferred stock) or (2) in whole but not in part, at any time within 90 days following a regulatory capital event (as defined in the certificate of designations for the preferred stock), in each case at a redemption price equal to $1,000 per share of preferred stock plus declared and unpaid dividends. Any dividends declared on the preferred stock will be 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 rate plus 5.783%. For more information on the other outstanding preferred stock issued by the Company, see Note 12: Common and Preferred Stock to the consolidated financial statements of the Company's annual report on Form 10-K for the year ended December 31, 2019.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2020
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 (loss) ("AOCI") were as follows (dollars in millions): Unrealized Gains on Available-for-Sale Investment Securities, Net of Tax (Losses) Gains on Cash Flow Hedges, Net of Tax Losses on Pension Plan, Net of Tax AOCI 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 Three Months Ended September 30, 2019 Balance at June 30, 2019 $ 112 $ (8) $ (187) $ (83) Net change 17 (8) — 9 Balance at September 30, 2019 $ 129 $ (16) $ (187) $ (74) 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 For the Nine Months Ended September 30, 2019 Balance at December 31, 2018 $ 10 $ 22 $ (188) $ (156) Net change 119 (38) 1 82 Balance at September 30, 2019 $ 129 $ (16) $ (187) $ (74) The following table presents each component of other comprehensive income (loss) ("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, 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 Net unrealized gains arising during the period $ — $ — $ — Amounts reclassified from AOCI 4 (1) 3 Net change $ 4 $ (1) $ 3 For the Three Months Ended September 30, 2019 Available-for-Sale Investment Securities Net unrealized holding gains arising during the period $ 24 $ (7) $ 17 Net change $ 24 $ (7) $ 17 Cash Flow Hedges Net unrealized losses arising during the period $ (9) $ 2 $ (7) Amounts reclassified from AOCI (2) 1 (1) Net change $ (11) $ 3 $ (8) 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 For the Nine Months Ended September 30, 2019 Available-for-Sale Investment Securities Net unrealized holding gains arising during the period $ 158 $ (39) $ 119 Net change $ 158 $ (39) $ 119 Cash Flow Hedges Net unrealized losses arising during the period $ (44) $ 11 $ (33) Amounts reclassified from AOCI (7) 2 (5) Net change $ (51) $ 13 $ (38) Pension Plan Unrealized gains arising during the period $ 1 $ — $ 1 Net change $ 1 $ — $ 1

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
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, except effective income tax rate): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 Income before income taxes $ 959 $ 994 $ 420 $ 2,911 Income tax expense $ 188 $ 224 $ 78 $ 662 Effective income tax rate 19.6 % 22.5 % 18.6 % 22.7 % Income tax expense decreased $36 million and $584 million for the three and nine months ended September 30, 2020, respectively, as compared to the same periods in 2019. Income tax expense and the effective tax rate for the three and nine months ended September 30, 2020 are lower due to lower projected pretax income for the full year. The Company calculates its provision for income taxes during interim reporting periods by applying an estimate of the annual effective tax rate for the full year to pretax income or loss excluding unusual or infrequently occurring discrete items. As the Company is projecting lower pretax income for the full year, the impact of certain favorable items, such as tax credits, on the effective tax rate is amplified, thereby resulting in a full-year effective tax rate that is lower than the historical annual effective tax rate. For the three and nine months ended September 30, 2020 and 2019, respectively, the effective tax rate was favorably impacted by the resolution of certain tax matters. The Company is subject to examination by the Internal Revenue Service ("IRS") and tax authorities in various state, local and foreign tax jurisdictions. The Company regularly assesses the likelihood of additional assessments or settlements in each of the taxing jurisdictions. The years 2011-2015 are currently under review by the IRS Office of Appeals. At this time, the potential change in unrecognized tax benefits is not expected to be significant 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, 2020
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 in millions, except per share amounts): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 Numerator Net income $ 771 $ 770 $ 342 $ 2,249 Preferred stock dividends (15) (15) (31) (31) Net income available to common stockholders 756 755 311 2,218 Income allocated to participating securities (5) (6) (2) (15) Net income allocated to common stockholders $ 751 $ 749 $ 309 $ 2,203 Denominator Weighted-average shares of common stock outstanding 306 317 307 323 Effect of dilutive common stock equivalents — — — — Weighted-average shares of common stock outstanding and common stock equivalents 306 317 307 323 Basic earnings per common share $ 2.45 $ 2.36 $ 1.00 $ 6.83 Diluted earnings per common share $ 2.45 $ 2.36 $ 1.00 $ 6.82 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, 2020 and 2019.

Capital Adequacy

Capital Adequacy	9 Months Ended
	Sep. 30, 2020
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Capital Adequacy	Capital Adequacy The Company is subject to the capital adequacy guidelines of the Federal Reserve and 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 have a direct material effect on the financial position and operating results of the Company and Discover Bank. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and Discover Bank must meet specific capital guidelines 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. The Company 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"). The Basel III rules, which became effective for the Company January 2015, were subject to phase-in periods through the end of 2018, based on the Company being classified as a "Standardized Approach" entity. As of January 1, 2019, the Basel III rules subject to transition have all been fully phased in with the exception of certain transition provisions that were frozen pursuant to regulation issued in November 2017. Pursuant to a final rule issued in July 2019, the transition provisions that were previously frozen have been replaced with new permanent rules effective in April 2020. Additionally, on March 27, 2020, federal bank regulatory agencies announced an interim final rule, which has since been adopted as a final rule, that allows banks that have implemented CECL the option to delay for two years the estimated impact of CECL on regulatory capital, 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 federal bank regulatory agencies final rule published on September 30, 2020. Pursuant to the final rule, the estimated impact of CECL on regulatory capital will be phased in over a three-year period beginning in 2022. As of September 30, 2020, the Company and Discover Bank met all Basel III minimum capital ratio requirements to which they were subject. The Company and Discover Bank also met the requirements to be considered "well-capitalized" under Regulation Y and prompt corrective action regulations, respectively, and there have been no conditions or events that management believes have changed the Company's or Discover Bank's category. To be categorized as "well-capitalized," the Company and Discover Bank must maintain minimum capital ratios as set forth in the table below. The following table shows the actual capital amounts and ratios of the Company 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, 2020 Total capital (to risk-weighted assets) Discover Financial Services $ 14,046 15.2 % $ 7,389 ≥8.0% $ 9,236 ≥10.0% Discover Bank $ 13,838 15.2 % $ 7,304 ≥8.0% $ 9,130 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 12,325 13.3 % $ 5,541 ≥6.0% $ 5,541 ≥6.0% Discover Bank $ 11,729 12.8 % $ 5,478 ≥6.0% $ 7,304 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 12,325 10.6 % $ 4,662 ≥4.0% N/A N/A Discover Bank $ 11,729 10.2 % $ 4,614 ≥4.0% $ 5,767 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 11,269 12.2 % $ 4,156 ≥4.5% N/A N/A Discover Bank $ 11,729 12.8 % $ 4,109 ≥4.5% $ 5,935 ≥6.5% December 31, 2019 Total capital (to risk-weighted assets) Discover Financial Services $ 13,250 13.5 % $ 7,860 ≥8.0% $ 9,825 ≥10.0% Discover Bank $ 13,441 13.8 % $ 7,776 ≥8.0% $ 9,720 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 11,595 11.8 % $ 5,895 ≥6.0% $ 5,895 ≥6.0% Discover Bank $ 11,203 11.5 % $ 5,832 ≥6.0% $ 7,776 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 11,595 10.3 % $ 4,482 ≥4.0% N/A N/A Discover Bank $ 11,203 10.1 % $ 4,435 ≥4.0% $ 5,544 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 11,032 11.2 % $ 4,421 ≥4.5% N/A N/A Discover Bank $ 11,203 11.5 % $ 4,374 ≥4.5% $ 6,318 ≥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, 2020
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, 2020, the Company had unused credit arrangements for loans of approximately $215.0 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. These arrangements, substantially all of which the Company can terminate at any time and which do not necessarily represent future cash requirements, are periodically reviewed based on account usage, customer creditworthiness and loan qualification. 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. Due diligence is performed by the Company, which is intended to ensure that asset guideline qualifications are met. If the assets pledged as collateral do not meet certain conforming guidelines, the Company may be required to replace, repurchase or sell such assets. In its credit card securitization activities, the Company would replace nonconforming receivables through the allocation of 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 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 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. • 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 is dependent upon the transaction volume processed between the time a potential counterparty defaults on its settlement and the time at which 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. In the event that 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 $50 million as of September 30, 2020. 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, 2020, the Company had not recorded any material contingent liability in the condensed consolidated financial statements for these counterparty exposures and 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, who 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 time 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 credits are issued by merchants 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, 2020 and 2019. The maximum potential amount of obligations of the Discover Network arising as a result of 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, 2020 2019 2020 2019 Aggregate sales transaction volume (1) $ 46,128 $ 44,332 $ 125,214 $ 125,922 (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, 2020 or December 31, 2019. 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 higher risk due to various factors such as time delays in the delivery of products or services. As of September 30, 2020 and December 31, 2019, the Company had escrow deposits and settlement withholdings of $19 million and $8 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, 2020
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, some of which may result in significant adverse judgments, settlements, fines, penalties, injunctions, decreases in regulatory ratings, customer restitution or other relief, which could materially impact the Company's condensed consolidated financial statements, increase its cost of operations, or limit its 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 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 expense was not material for the three and nine months ended September 30, 2020 and 2019. 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 those losses the likelihood of which 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 $220 million. This estimated range of reasonably possible losses is based upon currently available information for those proceedings in which the Company is involved and takes into account 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 legal 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 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. On July 22, 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 resolving the agency's investigation with respect to certain student loan servicing practices. The order required the Discover Subsidiaries to provide redress of approximately $16 million to consumers who may have been affected by the activities described in the order related to certain collection calls, overstatements of minimum payment due amounts in billing statements and provision of interest paid information to consumers and provide regulatory disclosures with respect to loans acquired in default. In addition, the Discover Subsidiaries were required to pay a $2.5 million civil money penalty to the CFPB. As required by the consent order, on October 19, 2015, the Discover Subsidiaries submitted to the CFPB a redress plan and a compliance plan designed to ensure that the Discover Subsidiaries provide redress and otherwise comply with the terms of the order. The CFPB is currently investigating Discover Bank's compliance with the order and certain student loan servicing practices. Discover Bank is cooperating with the CFPB in connection with the investigation. Discover Bank is enhancing the compliance plan submitted to the CFPB in 2015. The investigation could lead to a supervisory action, which may result in legal fees, penalties, fines and remediation expenses, and could require Discover Bank to change certain business practices. On March 8, 2016, a class action lawsuit was filed against the Company, other credit card networks, other issuing banks and EMVCo in the U.S. District Court for the Northern District of California (B&R Supermarket, Inc., d/b/a Milam's Market, et al. v. Visa, Inc. et al.) alleging a conspiracy by defendants to shift fraud liability to merchants with the migration to the EMV security standard and chip technology. Plaintiffs assert joint and several liability among the defendants and seek unspecified damages, including treble damages, attorneys' fees, costs and injunctive relief. In May 2017, the Court entered an order transferring the entire action to a federal court in New York that is presiding over certain related claims that are pending in the actions consolidated as MDL 1720. On August 28, 2020, the Court granted Plaintiff's Motion to Certify a Class. Defendants appealed the ruling on September 11, 2020. Discover filed a Letter Motion to Compel Arbitration on September 29, 2020. The Company is not in a position at this time to assess the likely outcome or its exposure, if any, with respect to this matter, but will seek to vigorously defend against all claims asserted by the plaintiffs.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
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 financial instruments, which is based on whether the inputs to the valuation techniques used to measure the fair value of each financial instrument 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 in which the inputs used to measure fair value may fall into different levels of the fair value hierarchy, the level in the fair value hierarchy within which the fair value measurement in its entirety is classified is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company may utilize both observable and unobservable inputs in determining the fair values of financial instruments classified within the Level 3 category. The determination of classification of its financial instruments within the fair value hierarchy is performed at least quarterly by the Company. For transfers in and out of the levels of the fair value hierarchy, the Company discloses the fair value measurement based on the value immediately preceding the transfer. 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, 2020 Assets Fair value - OCI U.S. Treasury securities $ 9,548 $ — $ — $ 9,548 Residential mortgage-backed securities - Agency — 11,025 — 11,025 Available-for-sale investment securities $ 9,548 $ 11,025 $ — $ 20,573 Liabilities Fair value - OCI Derivative financial instruments - cash flow hedges (1) $ — $ 1 $ — $ 1 Fair value - Net income Derivative financial instruments - fair value hedges (1) $ — $ 1 $ — $ 1 Balance at December 31, 2019 Assets Fair value - OCI U.S. Treasury securities $ 9,906 $ — $ — $ 9,906 Residential mortgage-backed securities - Agency — 417 — 417 Available-for-sale investment securities $ 9,906 $ 417 $ — $ 10,323 Liabilities Fair value - OCI Derivative financial instruments - cash flow hedges (1) $ — $ 2 $ — $ 2 Fair value - Net income Derivative financial instruments - fair value hedges (1) $ — $ 4 $ — $ 4 Derivative financial instruments - foreign exchange forward contracts (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 U.S. Treasury securities and residential mortgage-backed securities. The fair value estimates of investment securities classified as Level 1, consisting of U.S. Treasury securities, are determined based on quoted market prices for the same securities. The Company classifies residential mortgage-backed securities as Level 2, the fair value estimates of which are based on the best information available. This data may consist of observed market prices, 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 availability of information. The Company validates the fair value estimates provided by pricing services primarily by comparison 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, 2020, amounts reported in residential mortgage-backed securities reflect obligations issued by Fannie Mae, Freddie Mac and Ginnie Mae with a par value of $309 million, a weighted-average coupon of 2.81% and a weighted-average remaining maturity of three years, as well as the $10.7 billion of RMBS recorded as part of the securities lending transaction disclosed in Note 2: Investments. 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 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 to any changes to the valuation techniques performed by proprietary pricing models prior to implementation, working closely with the third-party valuation service and reviews the control objectives of the service at least annually. The Company corroborates the fair value of foreign exchange forward contracts through independent calculation of the fair value estimates. 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 is applicable if one or more of the assets is determined to be impaired. The Company had $59 million of impairments related to intangible assets during the nine months ended September 30, 2020. See Note 5: Intangible Assets for more information on the impact of COVID-19 on intangible assets. No impairments of goodwill were recognized during the three and nine months ended September 30, 2020. 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, 2020 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 290 $ — $ 290 $ 281 Held-to-maturity investment securities $ — $ 290 $ — $ 290 $ 281 Net loan receivables $ — $ — $ 89,767 $ 89,767 $ 80,434 Carrying value approximates fair value (1) Cash and cash equivalents $ 9,513 $ — $ — $ 9,513 $ 9,513 Restricted cash $ 576 $ — $ — $ 576 $ 576 Other short-term investments $ 8,048 $ — $ — $ 8,048 $ 8,048 Accrued interest receivables (2) $ — $ 1,008 $ — $ 1,008 $ 1,008 Liabilities Amortized cost Time deposits (3) $ — $ 31,739 $ — $ 31,739 $ 30,842 Short-term borrowings $ — $ 10,700 $ — $ 10,700 $ 10,700 Long-term borrowings - owed to securitization investors $ — $ 11,378 $ 136 $ 11,514 $ 11,425 Other long-term borrowings — 11,278 — 11,278 10,416 Long-term borrowings $ — $ 22,656 $ 136 $ 22,792 $ 21,841 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 170 $ — $ 170 $ 170 (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. Balance at December 31, 2019 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 274 $ — $ 274 $ 272 Held-to-maturity investment securities $ — $ 274 $ — $ 274 $ 272 Net loan receivables $ — $ — $ 96,094 $ 96,094 $ 92,511 Carrying value approximates fair value (1) Cash and cash equivalents $ 6,924 $ — $ — $ 6,924 $ 6,924 Restricted cash $ 40 $ — $ — $ 40 $ 40 Accrued interest receivables (2) $ — $ 1,044 $ — $ 1,044 $ 1,044 Liabilities Amortized cost Time deposits (3) $ — $ 34,910 $ — $ 34,910 $ 34,381 Long-term borrowings - owed to securitization investors $ — $ 14,211 $ 172 $ 14,383 $ 14,284 Other long-term borrowings — 12,189 — 12,189 11,417 Long-term borrowings $ — $ 26,400 $ 172 $ 26,572 $ 25,701 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 283 $ — $ 283 $ 283 (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, 2020
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 prior to engaging in any transaction with the Company. Counterparties are monitored on a regular basis by the Company 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, 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 of 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 payments on credit card securitized debt and deposits. The Company's outstanding cash flow hedge is for an initial maximum period of seven years for deposits. The derivatives are designated as hedges of the risk of changes in cash flows on the Company's Federal Funds rate-based interest payments and qualify for hedge accounting in accordance with ASC Topic 815, Derivatives and Hedging ("ASC 815"). 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, 2020, will be reclassified to interest expense as interest payments are accrued on certain of the Company's floating-rate securitized debt and deposits. During the next 12 months, the Company estimates it will reclassify $4 million of pretax expense to interest expense related to its derivatives designated as cash flow hedges. Fair Value Hedges The Company is exposed to changes in 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, benchmark interest rates as 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. 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, 2020 December 31, 2019 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 $ 300 1 $ — $ 1 $ 900 $ — $ 2 Interest rate swaps—fair value hedge $ 12,175 16 — 1 $ 14,275 — 4 Derivatives not designated as hedges Foreign exchange forward contracts (1) $ 23 6 — — $ 38 — 1 Total gross derivative assets/liabilities (2) — 2 — 7 Less: collateral held/posted (3) — (2) — (7) Total net derivative assets/liabilities $ — $ — $ — $ — (1) The foreign exchange forward contracts have notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 596 million as of September 30, 2020, and notional amounts of EUR 9 million, GBP 14 million, SGD 1 million and INR 596 million as of December 31, 2019. (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, 2020, the Company had no outstanding contracts. At December 31, 2019, the Company had two outstanding contracts with a total notional amount of $42 million and immaterial fair value. (3) Collateral amounts, which consist of both cash and investment securities, are limited to the related derivative asset/liability balance and do not include excess collateral received/pledged. September 30, 2020 December 31, 2019 Carrying Amount of Hedged Assets/Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of Hedged Assets/Liabilities Carrying Amount of Hedged Assets/Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of Hedged Assets/Liabilities Long-term borrowings $ 12,481 $ 339 $ 14,244 $ 13 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 in Income Interest Expense Deposits Long-Term Borrowings Other Income For the Three Months Ended September 30, 2020 Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded $ (287) $ (126) $ 17 The effects of cash flow and fair value hedging (Losses) gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (4) $ — $ — Gains (losses) on fair value hedging relationships Gains on hedged items $ — $ 59 $ — Gains (losses) on interest rate swaps — (9) — Total gains (losses) on fair value hedging relationships $ — $ 50 $ — For the Three Months Ended September 30, 2019 Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded $ (407) $ (231) $ 23 The effects of cash flow and fair value hedging Gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ 1 $ 1 $ — Gains (losses) on fair value hedging relationships Gains (losses) on hedged items $ — $ (20) $ — Gains on interest rate swaps — 12 — Total gains (losses) on fair value hedging relationships $ — $ (8) $ — Location and Amount of (Losses) Gains Recognized in Income Interest Expense Deposits Long-Term Borrowings Other Income For the Nine Months Ended September 30, 2020 Total amounts of income and expense line items presented in the statements of income in which 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) gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (9) $ (2) $ — Gains (losses) on fair value hedging relationships Gains (losses) on hedged items $ — $ (326) $ — Gains on interest rate swaps — 434 — Total gains on fair value hedging relationships $ — $ 108 $ — For the Nine Months Ended September 30, 2019 Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded $ (1,194) $ (721) $ 73 The effects of cash flow and fair value hedging Gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ 3 $ 4 $ — Gains (losses) on fair value hedging relationship Gains (losses) on hedged items $ — $ (160) $ — Gains on interest rate swaps — 128 — Total gains (losses) on fair value hedging relationships $ — $ (32) $ — 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 these derivatives held with that counterparty. The Company may also be required to post collateral with a counterparty for its fair value and cash flow hedge interest rate swaps depending on the credit rating it or Discover Bank receives from specified major credit rating agencies. 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. At September 30, 2020, Discover Bank's credit rating met specified thresholds set by its counterparties. However, if its credit rating is reduced below investment grade, Discover Bank would be required to post additional collateral. The amount of additional collateral as of September 30, 2020, would have been $9 million. DFS (Parent Company) had no outstanding derivatives as of September 30, 2020, and therefore, no collateral was required. The Company also has agreements with certain of its derivative counterparties that contain a provision where if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations.

Segment Disclosures

Segment Disclosures	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment Disclosures	Segment Disclosures The Company's business activities are managed in two segments: Direct Banking and Payment Services. • Direct Banking: The Direct 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 equity loans and other consumer lending and deposit products. The majority of Direct 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 Direct Banking segment. • Through its operation of the Discover Network, the Direct Banking segment incurs fixed marketing, servicing and infrastructure costs that are not specifically allocated among the segments, with the exception of an allocation of direct and incremental costs driven by the Company's Payment Services segment. • The assets of the Company 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): Direct Payment Total 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 91 — 91 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 For the Three Months Ended September 30, 2019 Interest income Credit card loans $ 2,465 $ — $ 2,465 Private student loans 204 — 204 Personal loans 249 — 249 Other 122 — 122 Total interest income 3,040 — 3,040 Interest expense 638 — 638 Net interest income 2,402 — 2,402 Provision for credit losses (1) 799 — 799 Other income 409 89 498 Other expense 1,069 38 1,107 Income before income taxes $ 943 $ 51 $ 994 (1) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. The following table presents segment data (dollars in millions): Direct Payment Total 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 284 — 284 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 For the Nine Months Ended September 30, 2019 Interest income Credit card loans $ 7,223 $ — $ 7,223 Private student loans 612 — 612 Personal loans 727 — 727 Other 391 1 392 Total interest income 8,953 1 8,954 Interest expense 1,915 — 1,915 Net interest income 7,038 1 7,039 Provision for credit losses (1) 2,395 — 2,395 Other income 1,217 259 1,476 Other expense 3,097 112 3,209 Income before income tax expense $ 2,763 $ 148 $ 2,911 (1) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2020
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 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): Direct Banking Payment Services Total 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 For the Three Months Ended September 30, 2019 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 238 $ 17 $ 255 Protection products revenue 48 — 48 Transaction processing revenue — 52 52 Other income 3 20 23 Total other income subject to ASC 606 (2) 289 89 378 Other income not subject to ASC 606 Loan fee income 120 — 120 Total other income not subject to ASC 606 120 — 120 Total other income by operating segment $ 409 $ 89 $ 498 (1) Net of rewards, including Cashback Bonus rewards, of $514 million and $520 million for the three months ended September 30, 2020 and 2019, respectively. (2) Excludes $1 million of deposit product fees that are reported within net interest income for the three months ended September 30, 2020. Deposit product fees were immaterial for the three months ended September 30, 2019. 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): Direct Banking Payment Services Total 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 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 For the Nine Months Ended September 30, 2019 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 738 $ 47 $ 785 Protection products revenue 146 — 146 Transaction processing revenue — 146 146 Other income 7 66 73 Total other income subject to ASC 606 (2) 891 259 1,150 Other income not subject to ASC 606 Loan fee income 326 — 326 Total other income not subject to ASC 606 326 — 326 Total other income by operating segment $ 1,217 $ 259 $ 1,476 (1) Net of rewards, including Cashback Bonus rewards, of $1.4 billion for the nine months ended September 30, 2020 and 2019. (2) Excludes $2 million of deposit product fees that are reported within net interest income for the nine months ended September 30, 2020 and 2019. 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 of the Company's annual report on Form 10-K for the year ended December 31, 2019.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company has evaluated events and transactions that have occurred subsequent to September 30, 2020 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, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies	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 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.

Loan Receivables Loan Receivabl

Loan Receivables Loan Receivables (Policies)	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Loan Receivables Policy	Loan Receivables Loan receivables consist of credit card receivables and other loan receivables. Loan receivables also include unamortized net deferred loan origination fees and costs. Credit card loan receivables are reported at their principal amounts outstanding and include uncollected billed interest and fees and are reduced for unearned revenue related to balance transfer fees. Other loan receivables consist of student loans, personal loans and other loans and are reported at their principal amounts outstanding. For student loans, principal amounts outstanding also include accrued interest that has been capitalized. The Company's loan receivables are deemed to be held for investment at origination or acquisition because management has the intent and ability to hold them for the foreseeable future. Cash flows associated with loans originated or acquired for investment are classified as cash flows from investing activities, regardless of a subsequent change in intent.
Allowance for Credit Losses Policy	Allowance for Credit Losses The Company maintains an allowance for credit losses at a level that is appropriate to absorb credit losses anticipated over the remaining expected life of loan receivables as of the balance sheet date. The estimate of expected credit losses considers uncollectible principal, interest and fees associated with the Company's loan receivables existing as of the balance sheet date. Additionally, the estimate includes expected recoveries of amounts that were either previously charged off or are expected to be charged off. The allowance is evaluated quarterly for appropriateness and is maintained through an adjustment to the provision for credit losses. Charge-offs of principal amounts of loans outstanding are deducted from the allowance and subsequent recoveries of such amounts increase the allowance. Charge-offs of loan balances representing unpaid interest and fees result in a reversal of interest and fee income, respectively, which is effectively a reclassification of the provision for credit losses. The Company calculates its allowance for credit losses by estimating expected credit losses separately for classes of the loan portfolio with similar risk characteristics, which results in segmenting the portfolio by loan product type. The allowance for credit losses for each loan product type is based on: 1) a reasonable and supportable forecast period, 2) a reversion period and 3) a post-reversion period based on historical information covering the remaining life of the loan, all of which is netted with expected recoveries. The lengths of the reasonable and supportable forecast and reversion periods can vary and are subject to a quarterly assessment that considers the economic outlook and level of variability among macroeconomic forecasts. Generally, a straight-line method is used to revert from the reasonable and supportable forecast period to the post-reversion period, but in certain stressed scenarios, a weighted approach may be deemed more appropriate. Several analyses are used to help estimate credit losses anticipated over the remaining expected life of loan receivables as of the balance sheet date. The Company's estimation process includes models that predict customer losses based on risk characteristics and portfolio attributes, macroeconomic variables, and historical data and analysis. There is a significant amount of judgment applied in selecting inputs and analyzing the results produced by the models to determine the allowance. For credit card loans, the Company uses a modeling framework that includes the following components for estimating expected credit losses: • Probability of default: this model estimates the probability of charge-off at different points in time over the life of each loan. • Exposure at default: this model estimates the portion of the balance sheet date balance remaining at any given time of charge-off for each loan. Given that there is no stated life of a receivable balance on a revolving credit card account, the Company applies a percentage of expected payments to estimate the portion of the balance that would remain at the time of charge-off. • Loss given default: this model estimates the percentage of exposure (i.e. net loss) at time of charge-off that cannot be recovered, with the offsetting forecast recoveries being the driver of this estimate. • Recoveries from previously charged-off accounts are estimated separately and are netted as part of the aggregation of all of the components of the card loss modeling framework. For student loans and personal loans, the Company uses vintage-based models that estimate expected credit losses over the life of the loan, net of recovery estimates, impacted mainly by time elapsed since origination, credit quality of origination vintages and macroeconomic forecasts. The models described above for credit card, student and personal loans are developed utilizing historical data and applicable macroeconomic variable inputs based on statistical analysis and behavioral relationships with credit performance. Expected recoveries from loans charged off as of the balance sheet date are modeled separately and included in the allowance estimate. The Company leverages these models and recent macroeconomic forecasts for the portion of the estimate associated with the reasonable and supportable forecast period. To estimate expected credit losses for the remainder of the life of the credit card loans, the Company reverts to historical experience of credit card loans with characteristics similar to those as of the balance sheet date and observed over various phases of a credit cycle. To estimate expected credit losses for the remainder of the life of student and personal loans, the Company reverts to use of average macroeconomic variables over an appropriate historical period. The considerations in these models include past and current loan performance, loan growth and seasoning, risk management practices, account collection strategies, economic conditions, bankruptcy filings, policy changes and forecasting uncertainties. Consideration of past and current loan performance includes the post-modification performance of loans modified in a TDR. For the credit card loan portfolio, the Company estimates its credit losses on a loan-level basis, which includes loans that are delinquent and/or no longer accruing interest and/or loans that have been modified under a TDR. For the remainder of its portfolio, including student, personal and other loans, the Company estimates its credit losses on a pooled basis. For all loan types, recoveries are estimated at a pooled level based on estimates of future cash flows derived using historical experience. Interest on credit card loans is included in the estimate of expected credit losses once billed to the customer (i.e., once the interest becomes part of the loan balance). An allowance for credit losses is measured for accrued interest on all other loans and is presented as part of allowance for credit losses in the consolidated statements of financial condition. The Company records a liability for expected credit losses for unfunded commitments on all other loans, which is presented as part of accrued expenses and other liabilities in the consolidated statements of financial condition. This liability is evaluated quarterly for appropriateness and is maintained through an adjustment to the provision for credit losses. No liability for expected credit losses is required for unused lines of credit on the Company’s credit card loans because they are unconditionally cancellable.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2020
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, U.S. Treasury bills (1) $ 2,139 $ — U.S. Treasury bills - Pledged 5,909 — Total other short-term investments $ 8,048 $ — U.S. Treasury securities $ 3,930 $ 9,785 U.S. Treasury securities - Pledged (2) 5,618 121 Total U.S. Treasury securities 9,548 9,906 Residential mortgage-backed securities - Agency (3) 11,306 689 Total investment securities $ 20,854 $ 10,595 (1) Includes U.S. Treasury bills with maturity dates greater than 90 days but less than one year at the time of acquisition. (2) As of September 30, 2020 and December 31, 2019, includes $135 million and $121 million, respectively, of U.S. Treasury securities pledged as swap collateral other than amounts associated with the September 2020 securities lending transaction. (3) Consists of residential mortgage-backed securities issued by Fannie Mae, Freddie Mac and Ginnie Mae.
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, 2020 Available-for-Sale Investment Securities (1) U.S. Treasury securities $ 9,134 $ 414 $ — $ 9,548 Residential mortgage-backed securities - Agency 11,014 11 — 11,025 Total available-for-sale investment securities $ 20,148 $ 425 $ — $ 20,573 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 281 $ 9 $ — $ 290 Total held-to-maturity investment securities $ 281 $ 9 $ — $ 290 At December 31, 2019 Available-for-Sale Investment Securities (1) U.S. Treasury securities $ 9,759 $ 155 $ (8) $ 9,906 Residential mortgage-backed securities - Agency 414 3 — 417 Total available-for-sale investment securities $ 10,173 $ 158 $ (8) $ 10,323 Held-to-Maturity Investment Securities (2) Residential mortgage-backed securities - Agency (3) $ 272 $ 3 $ (1) $ 274 Total held-to-maturity investment securities $ 272 $ 3 $ (1) $ 274 (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 that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.
Schedule of Fair Value of Securities in a Continuous Unrealized Loss Position for Less Than 12 Months and More Than 12 Months	The following table provides information about available-for-sale investment securities with aggregate gross unrealized losses and the length of time that individual investment securities have been in a continuous unrealized loss position (dollars in millions): Number of Securities in a Loss Position Less than 12 months More than 12 months Fair Unrealized Fair Unrealized At December 31, 2019 Available-for-Sale Investment Securities U.S. Treasury securities 11 $ 1,402 $ (8) $ — $ —
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, 2020 One Year After One After Five After Ten Total Available-for-Sale Investment Securities—Amortized Cost U.S. Treasury securities $ 1,880 $ 7,254 $ — $ — $ 9,134 Residential mortgage-backed securities - Agency (1) — 54 291 10,669 11,014 Total available-for-sale investment securities $ 1,880 $ 7,308 $ 291 $ 10,669 $ 20,148 Held-to-Maturity Investment Securities—Amortized Cost Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 281 $ 281 Total held-to-maturity investment securities $ — $ — $ — $ 281 $ 281 Available-for-Sale Investment Securities—Fair Values U.S. Treasury securities $ 1,900 $ 7,648 $ — $ — $ 9,548 Residential mortgage-backed securities - Agency (1) — 56 300 10,669 11,025 Total available-for-sale investment securities $ 1,900 $ 7,704 $ 300 $ 10,669 $ 20,573 Held-to-Maturity Investment Securities—Fair Values Residential mortgage-backed securities - Agency (1) $ — $ — $ — $ 290 $ 290 Total held-to-maturity investment securities $ — $ — $ — $ 290 $ 290 (1) Maturities of residential mortgage-backed securities are reflective of the contractual maturities of the investment.

Loan Receivables (Tables)

Loan Receivables (Tables)	9 Months Ended
	Sep. 30, 2020
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) $ 69,656 $ 77,181 Other loans (3) Private student loans (4) 10,016 9,653 Personal loans 7,211 7,687 Other 1,777 1,373 Total other loans 19,004 18,713 Total loan receivables 88,660 95,894 Allowance for credit losses (5) (8,226) (3,383) Net loan receivables $ 80,434 $ 92,511 (1) Amounts include carrying values of $15.4 billion and $18.9 billion underlying investors' interest in trust debt at September 30, 2020 and December 31, 2019, respectively, and $11.6 billion and $12.7 billion in seller's interest at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and 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 $380 million and $471 million at September 30, 2020 and December 31, 2019, 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 $527 million, $47 million and $6 million, respectively, at September 30, 2020 and $461 million, $53 million and $4 million, respectively, at December 31, 2019. (4) Amounts include carrying values of $261 million and $292 million in loans pledged as collateral against the note issued from a student loan securitization trust at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information. (5) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
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, 2020 December 31, 2019 660 and Above Less than 660 660 and Above Less than 660 $ % $ % $ % $ % Credit card loans (1) $ 57,148 82 % $ 12,508 18 % $ 61,997 80 % $ 15,184 20 % Private student loans by origination year (2)(3) 2020 $ 983 97 % $ 29 3 % 2019 1,690 97 % 57 3 % $ 1,176 93 % $ 92 7 % 2018 1,399 96 % 60 4 % 1,518 95 % 79 5 % 2017 1,076 95 % 57 5 % 1,198 95 % 69 5 % 2016 817 94 % 48 6 % 934 94 % 58 6 % Prior 3,586 94 % 214 6 % 4,229 93 % 300 7 % Total private student loans $ 9,551 95 % $ 465 5 % $ 9,055 94 % $ 598 6 % Personal loans by origination year 2020 $ 2,175 99 % $ 15 1 % 2019 2,506 97 % 89 3 % $ 3,529 98 % $ 62 2 % 2018 1,221 92 % 101 8 % 1,941 93 % 140 7 % 2017 680 89 % 81 11 % 1,167 90 % 136 10 % 2016 242 88 % 34 12 % 475 88 % 65 12 % Prior 55 82 % 12 18 % 145 84 % 27 16 % Total personal loans $ 6,879 95 % $ 332 5 % $ 7,257 94 % $ 430 6 % (1) Amounts include $1.0 billion and $956 million of revolving line-of-credit arrangements that were converted to term loans as a result of a TDR program as of September 30, 2020 and December 31, 2019, respectively. (2) A majority of student loans 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, 2020 December 31, 2019 30-89 Days 90 or Total Past 30-89 Days 90 or Total Past Credit card loans $ 678 $ 650 $ 1,328 $ 999 $ 1,020 $ 2,019 Private student loans by origination year (1)(2) 2020 $ — $ — $ — 2019 3 — 3 $ 1 $ — $ 1 2018 11 3 14 4 1 5 2017 13 4 17 11 2 13 2016 14 4 18 14 5 19 Prior 76 21 97 106 37 143 Total private student loans $ 117 $ 32 $ 149 $ 136 $ 45 $ 181 Personal loans by origination year 2020 $ 4 $ 1 $ 5 2019 19 7 26 $ 11 $ 3 $ 14 2018 17 7 24 27 11 38 2017 11 5 16 22 10 32 2016 4 2 6 10 5 15 Prior 1 1 2 4 2 6 Total personal loans $ 56 $ 23 $ 79 $ 74 $ 31 $ 105 (1) 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. (2) Includes PCD loans for all periods presented.
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, 2020 Credit Card Loans Student Loans Personal Loans Other Loans Total 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 Three Months Ended September 30, 2019 Credit Card Loans Student Loans Personal Loans Other Loans Total Balance at June 30, 2019 (2) $ 2,691 $ 167 $ 338 $ 6 $ 3,202 Additions Provision for credit losses (2) 719 (6) 86 — 799 Deductions Charge-offs (784) (17) (89) (1) (891) Recoveries 173 3 13 — 189 Net charge-offs (3) (611) (14) (76) (1) (702) Balance at September 30, 2019 (2) $ 2,799 $ 147 $ 348 $ 5 $ 3,299 For the Nine Months Ended September 30, 2020 Credit Card Loans Student Loans Personal Loans Other Loans Total Balance at December 31, 2019 (2) $ 2,883 $ 148 $ 348 $ 4 $ 3,383 Cumulative effect of ASU No. 2016-13 adoption (4) 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 For the Nine Months Ended September 30, 2019 Credit Card Loans Student Loans Personal Loans Other Loans Total Balance at December 31, 2018 (2) $ 2,528 $ 169 $ 338 $ 6 $ 3,041 Additions Provision for credit losses (2) 2,121 24 250 — 2,395 Deductions Charge-offs (2,347) (54) (274) (1) (2,676) Recoveries 497 10 34 — 541 Net charge-offs (3) (1,850) (44) (240) (1) (2,135) Other (5) — (2) — — (2) Balance at September 30, 2019 (2) $ 2,799 $ 147 $ 348 $ 5 $ 3,299 (1) Excludes a $40 million build and $17 million build of the liability for expected credit losses on unfunded commitments for the three months and nine months ended September 30, 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 adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. (3) Prior to adoption of ASU No. 2016-13 on January 1, 2020, net charge-offs on PCD loans generally did not result in a charge to earnings. (4) Represents the adjustment to allowance for credit losses as a result of adoption of ASU No. 2016-13 on January 1, 2020. (5) Net change in reserves on PCD pools having no remaining non-accretable difference (prior to 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, 2020 2019 2020 2019 Interest and fees accrued subsequently charged off, net of recoveries (recorded as a reduction of interest income) $ 114 $ 127 $ 393 $ 382 Fees accrued subsequently charged off, net of recoveries (recorded as a reduction to other income) $ 27 $ 29 $ 95 $ 90
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 by each class of loan receivables (dollars in millions): 30-89 Days 90 or Total Past 90 or Total Non-accruing (1) At September 30, 2020 Credit card loans $ 678 $ 650 $ 1,328 $ 604 $ 196 Other loans Private student loans (2) 117 32 149 31 12 Personal loans 56 23 79 22 9 Other 8 3 11 — 11 Total other loans 181 58 239 53 32 Total loan receivables $ 859 $ 708 $ 1,567 $ 657 $ 228 At December 31, 2019 Credit card loans $ 999 $ 1,020 $ 2,019 $ 940 $ 237 Other loans Private student loans (2) 136 45 181 45 11 Personal loans 74 31 105 29 12 Other 5 2 7 — 6 Total other loans 215 78 293 74 29 Total loan receivables $ 1,214 $ 1,098 $ 2,312 $ 1,014 $ 266 (1) The Company estimates that the gross interest income that would have been recorded in accordance with the original terms of non-accruing credit card loans was $7 million and $12 million for the three months ended September 30, 2020 and 2019, respectively, and $25 million and $34 million for the nine months ended September 30, 2020 and 2019, respectively. The Company does not separately track the amount of gross interest income that would have been recorded in accordance with the original terms of loans. This amount was estimated based on customers' current balances and most recent interest rates. (2) Includes PCD loans for all periods presented.
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, 2020 2019 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 20,779 $ 150 97,046 $ 623 Private student loans 118 $ 2 1,692 $ 31 Personal loans 2,505 $ 33 2,859 $ 39 For the Nine Months Ended September 30, 2020 2019 Number of Accounts Balances Number of Accounts Balances Accounts that entered a TDR program during the period Credit card loans (1) 130,869 $ 875 273,970 $ 1,766 Private student loans 1,767 $ 32 4,978 $ 92 Personal loans 6,315 $ 83 8,129 $ 110 (1) Accounts that entered a credit card TDR program include $143 million and $173 million that were converted from revolving line-of-credit arrangements to term loans during the three months ended September 30, 2020 and 2019, respectively, and $529 million and $336 million for the nine months ended September 30, 2020 and 2019, respectively.
Schedule of Troubled Debt Restructurings That Subsequently Defaulted	The following table presents the carrying value of loans that experienced a payment 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, 2020 2019 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) 8,983 $ 52 19,108 $ 109 Private student loans (3) 272 $ 6 396 $ 8 Personal loans (2) 624 $ 9 1,131 $ 15 For the Nine Months Ended September 30, 2020 2019 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) 41,285 $ 235 50,980 $ 294 Private student loans (3) 876 $ 18 966 $ 19 Personal loans (2) 2,446 $ 36 2,925 $ 42 (1) Terms revert back to the pre-modification terms for customers who default from a temporary program and charging privileges remain suspended in most cases. (2) For credit card loans and personal loans, a customer defaults from a TDR program after two consecutive missed payments. The outstanding balance upon default is generally the loan balance at the end of the month prior to default.

Credit Card and Student Loan _2

Credit Card and Student Loan Securitization Activities (Tables)	9 Months Ended
	Sep. 30, 2020
Variable Interest Entities Disclosure [Abstract]
Schedule of Restricted Credit Card Securitized Assets [Text Block]	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 $ 567 $ 28 Investors' interests held by third-party investors 11,150 14,100 Investors' interests held by wholly-owned subsidiaries of Discover Bank 4,249 4,796 Seller's interest 11,627 12,652 Loan receivables (1) 27,026 31,548 Allowance for credit losses allocated to securitized loan receivables (1)(2) (1,964) (1,179) Net loan receivables 25,062 30,369 Other 4 5 Carrying value of assets of consolidated variable interest entities $ 25,633 $ 30,402 (1) The Company maintains its allowance for credit losses at an amount sufficient to absorb expected losses inherent in all loan receivables, which includes all loan receivables in the trusts. Therefore, credit risk associated with the transferred receivables is fully reflected on the Company's balance sheet in accordance with GAAP. (2) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
Schedule of Restricted Student Loan Securitized Assets [Table Text Block]	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 $ 12 Student loan receivables 261 292 Carrying value of assets of consolidated variable interest entities $ 270 $ 304

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2020
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 $ 21,071 $ 25,113 Certificates of deposit in amounts $100,000 or greater (1) 9,771 9,268 Savings deposits, including money market deposit accounts 46,096 37,574 Total interest-bearing deposits $ 76,938 $ 71,955 (1) Includes $2.8 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, 2020 and December 31, 2019, 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 $ 1,734 Over three months through six months 2,375 Over six months through twelve months 3,166 Over twelve months 2,496 Total $ 9,771
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, 2020 $ 4,861 2021 15,825 2022 4,353 2023 2,214 2024 1,357 Thereafter 2,232 Total $ 30,842

Long-Term Borrowings (Tables)

Long-Term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 December 31, 2019 Maturity Interest Weighted-Average Interest Rate Outstanding Amount Outstanding Amount Securitized Debt Fixed-rate asset-backed securities (1) 2020-2024 1.85%-3.32% 2.70% $ 6,621 $ 8,609 Floating-rate asset-backed securities (2) 2021-2024 0.38%-0.75% 0.55% 4,668 5,515 Total Discover Card Master Trust I and Discover Card Execution Note Trust 11,289 14,124 Floating-rate asset-backed security (3)(4) 2031 4.25% 4.25% 136 160 Total student loan securitization trust 136 160 Total long-term borrowings - owed to securitization investors 11,425 14,284 Discover Financial Services (Parent Company) Fixed-rate senior notes 2022-2027 3.75%-5.20% 4.16% 3,327 3,296 Fixed-rate retail notes 2021-2031 2.85%-4.60% 3.73% 336 340 Discover Bank Fixed-rate senior bank notes (1) 2021-2030 2.45%-4.65% 3.89% 6,236 6,785 Fixed-rate subordinated bank notes 2028-2028 4.68%-4.68% 4.68% 517 996 Total long-term borrowings $ 21,841 $ 25,701 (1) The Company uses interest rate swaps to hedge portions of these long-term borrowings against changes in fair value attributable to changes in LIBOR or Overnight Index Swap ("OIS") Rate. Use of these interest rate swaps impacts carrying value of the debt. See Note 16: Derivatives and Hedging Activities. (2) Discover Card Execution Note Trust floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month LIBOR + 23 to 60 basis points as of September 30, 2020. (3) The 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, 2020. (4) Repayment of this debt is dependent upon the timing of principal and interest payments on the underlying student loans. The date shown represents 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, 2020 2020 $ 550 2021 4,232 2022 5,204 2023 3,411 2024 2,630 Thereafter 5,814 Total $ 21,841

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2020
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 (loss) ("AOCI") were as follows (dollars in millions): Unrealized Gains on Available-for-Sale Investment Securities, Net of Tax (Losses) Gains on Cash Flow Hedges, Net of Tax Losses on Pension Plan, Net of Tax AOCI 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 Three Months Ended September 30, 2019 Balance at June 30, 2019 $ 112 $ (8) $ (187) $ (83) Net change 17 (8) — 9 Balance at September 30, 2019 $ 129 $ (16) $ (187) $ (74) 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 For the Nine Months Ended September 30, 2019 Balance at December 31, 2018 $ 10 $ 22 $ (188) $ (156) Net change 119 (38) 1 82 Balance at September 30, 2019 $ 129 $ (16) $ (187) $ (74)
Schedule of Other Comprehensive Income Before Reclassifications and Amounts Reclassified from AOCI	The following table presents each component of other comprehensive income (loss) ("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, 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 Net unrealized gains arising during the period $ — $ — $ — Amounts reclassified from AOCI 4 (1) 3 Net change $ 4 $ (1) $ 3 For the Three Months Ended September 30, 2019 Available-for-Sale Investment Securities Net unrealized holding gains arising during the period $ 24 $ (7) $ 17 Net change $ 24 $ (7) $ 17 Cash Flow Hedges Net unrealized losses arising during the period $ (9) $ 2 $ (7) Amounts reclassified from AOCI (2) 1 (1) Net change $ (11) $ 3 $ (8) 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 For the Nine Months Ended September 30, 2019 Available-for-Sale Investment Securities Net unrealized holding gains arising during the period $ 158 $ (39) $ 119 Net change $ 158 $ (39) $ 119 Cash Flow Hedges Net unrealized losses arising during the period $ (44) $ 11 $ (33) Amounts reclassified from AOCI (7) 2 (5) Net change $ (51) $ 13 $ (38) Pension Plan Unrealized gains arising during the period $ 1 $ — $ 1 Net change $ 1 $ — $ 1

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2020
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, except effective income tax rate): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 Income before income taxes $ 959 $ 994 $ 420 $ 2,911 Income tax expense $ 188 $ 224 $ 78 $ 662 Effective income tax rate 19.6 % 22.5 % 18.6 % 22.7 %

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
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 in millions, except per share amounts): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 Numerator Net income $ 771 $ 770 $ 342 $ 2,249 Preferred stock dividends (15) (15) (31) (31) Net income available to common stockholders 756 755 311 2,218 Income allocated to participating securities (5) (6) (2) (15) Net income allocated to common stockholders $ 751 $ 749 $ 309 $ 2,203 Denominator Weighted-average shares of common stock outstanding 306 317 307 323 Effect of dilutive common stock equivalents — — — — Weighted-average shares of common stock outstanding and common stock equivalents 306 317 307 323 Basic earnings per common share $ 2.45 $ 2.36 $ 1.00 $ 6.83 Diluted earnings per common share $ 2.45 $ 2.36 $ 1.00 $ 6.82

Capital Adequacy (Tables)

Capital Adequacy (Tables)	9 Months Ended
	Sep. 30, 2020
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 the Company 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, 2020 Total capital (to risk-weighted assets) Discover Financial Services $ 14,046 15.2 % $ 7,389 ≥8.0% $ 9,236 ≥10.0% Discover Bank $ 13,838 15.2 % $ 7,304 ≥8.0% $ 9,130 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 12,325 13.3 % $ 5,541 ≥6.0% $ 5,541 ≥6.0% Discover Bank $ 11,729 12.8 % $ 5,478 ≥6.0% $ 7,304 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 12,325 10.6 % $ 4,662 ≥4.0% N/A N/A Discover Bank $ 11,729 10.2 % $ 4,614 ≥4.0% $ 5,767 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 11,269 12.2 % $ 4,156 ≥4.5% N/A N/A Discover Bank $ 11,729 12.8 % $ 4,109 ≥4.5% $ 5,935 ≥6.5% December 31, 2019 Total capital (to risk-weighted assets) Discover Financial Services $ 13,250 13.5 % $ 7,860 ≥8.0% $ 9,825 ≥10.0% Discover Bank $ 13,441 13.8 % $ 7,776 ≥8.0% $ 9,720 ≥10.0% Tier 1 capital (to risk-weighted assets) Discover Financial Services $ 11,595 11.8 % $ 5,895 ≥6.0% $ 5,895 ≥6.0% Discover Bank $ 11,203 11.5 % $ 5,832 ≥6.0% $ 7,776 ≥8.0% Tier 1 capital (to average assets) Discover Financial Services $ 11,595 10.3 % $ 4,482 ≥4.0% N/A N/A Discover Bank $ 11,203 10.1 % $ 4,435 ≥4.0% $ 5,544 ≥5.0% Common Equity Tier 1 (to risk-weighted assets) Discover Financial Services $ 11,032 11.2 % $ 4,421 ≥4.5% N/A N/A Discover Bank $ 11,203 11.5 % $ 4,374 ≥4.5% $ 6,318 ≥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, 2020
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, 2020 2019 2020 2019 Aggregate sales transaction volume (1) $ 46,128 $ 44,332 $ 125,214 $ 125,922 (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, 2020
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, 2020 Assets Fair value - OCI U.S. Treasury securities $ 9,548 $ — $ — $ 9,548 Residential mortgage-backed securities - Agency — 11,025 — 11,025 Available-for-sale investment securities $ 9,548 $ 11,025 $ — $ 20,573 Liabilities Fair value - OCI Derivative financial instruments - cash flow hedges (1) $ — $ 1 $ — $ 1 Fair value - Net income Derivative financial instruments - fair value hedges (1) $ — $ 1 $ — $ 1 Balance at December 31, 2019 Assets Fair value - OCI U.S. Treasury securities $ 9,906 $ — $ — $ 9,906 Residential mortgage-backed securities - Agency — 417 — 417 Available-for-sale investment securities $ 9,906 $ 417 $ — $ 10,323 Liabilities Fair value - OCI Derivative financial instruments - cash flow hedges (1) $ — $ 2 $ — $ 2 Fair value - Net income Derivative financial instruments - fair value hedges (1) $ — $ 4 $ — $ 4 Derivative financial instruments - foreign exchange forward contracts (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, 2020 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 290 $ — $ 290 $ 281 Held-to-maturity investment securities $ — $ 290 $ — $ 290 $ 281 Net loan receivables $ — $ — $ 89,767 $ 89,767 $ 80,434 Carrying value approximates fair value (1) Cash and cash equivalents $ 9,513 $ — $ — $ 9,513 $ 9,513 Restricted cash $ 576 $ — $ — $ 576 $ 576 Other short-term investments $ 8,048 $ — $ — $ 8,048 $ 8,048 Accrued interest receivables (2) $ — $ 1,008 $ — $ 1,008 $ 1,008 Liabilities Amortized cost Time deposits (3) $ — $ 31,739 $ — $ 31,739 $ 30,842 Short-term borrowings $ — $ 10,700 $ — $ 10,700 $ 10,700 Long-term borrowings - owed to securitization investors $ — $ 11,378 $ 136 $ 11,514 $ 11,425 Other long-term borrowings — 11,278 — 11,278 10,416 Long-term borrowings $ — $ 22,656 $ 136 $ 22,792 $ 21,841 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 170 $ — $ 170 $ 170 (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. Balance at December 31, 2019 Quoted Prices in Active Markets Significant Significant Total Carrying Assets Amortized cost Residential mortgage-backed securities - Agency $ — $ 274 $ — $ 274 $ 272 Held-to-maturity investment securities $ — $ 274 $ — $ 274 $ 272 Net loan receivables $ — $ — $ 96,094 $ 96,094 $ 92,511 Carrying value approximates fair value (1) Cash and cash equivalents $ 6,924 $ — $ — $ 6,924 $ 6,924 Restricted cash $ 40 $ — $ — $ 40 $ 40 Accrued interest receivables (2) $ — $ 1,044 $ — $ 1,044 $ 1,044 Liabilities Amortized cost Time deposits (3) $ — $ 34,910 $ — $ 34,910 $ 34,381 Long-term borrowings - owed to securitization investors $ — $ 14,211 $ 172 $ 14,383 $ 14,284 Other long-term borrowings — 12,189 — 12,189 11,417 Long-term borrowings $ — $ 26,400 $ 172 $ 26,572 $ 25,701 Carrying value approximates fair value (1) Accrued interest payables (2) $ — $ 283 $ — $ 283 $ 283 (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, 2020
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, 2020 December 31, 2019 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 $ 300 1 $ — $ 1 $ 900 $ — $ 2 Interest rate swaps—fair value hedge $ 12,175 16 — 1 $ 14,275 — 4 Derivatives not designated as hedges Foreign exchange forward contracts (1) $ 23 6 — — $ 38 — 1 Total gross derivative assets/liabilities (2) — 2 — 7 Less: collateral held/posted (3) — (2) — (7) Total net derivative assets/liabilities $ — $ — $ — $ — (1) The foreign exchange forward contracts have notional amounts of EUR 6 million, GBP 6 million, SGD 1 million and INR 596 million as of September 30, 2020, and notional amounts of EUR 9 million, GBP 14 million, SGD 1 million and INR 596 million as of December 31, 2019. (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, 2020, the Company had no outstanding contracts. At December 31, 2019, the Company had two outstanding contracts with a total notional amount of $42 million and immaterial fair value. (3) Collateral amounts, which consist of both 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, 2020 December 31, 2019 Carrying Amount of Hedged Assets/Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of Hedged Assets/Liabilities Carrying Amount of Hedged Assets/Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of Hedged Assets/Liabilities Long-term borrowings $ 12,481 $ 339 $ 14,244 $ 13
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 in Income Interest Expense Deposits Long-Term Borrowings Other Income For the Three Months Ended September 30, 2020 Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded $ (287) $ (126) $ 17 The effects of cash flow and fair value hedging (Losses) gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (4) $ — $ — Gains (losses) on fair value hedging relationships Gains on hedged items $ — $ 59 $ — Gains (losses) on interest rate swaps — (9) — Total gains (losses) on fair value hedging relationships $ — $ 50 $ — For the Three Months Ended September 30, 2019 Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded $ (407) $ (231) $ 23 The effects of cash flow and fair value hedging Gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ 1 $ 1 $ — Gains (losses) on fair value hedging relationships Gains (losses) on hedged items $ — $ (20) $ — Gains on interest rate swaps — 12 — Total gains (losses) on fair value hedging relationships $ — $ (8) $ — Location and Amount of (Losses) Gains Recognized in Income Interest Expense Deposits Long-Term Borrowings Other Income For the Nine Months Ended September 30, 2020 Total amounts of income and expense line items presented in the statements of income in which 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) gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ (9) $ (2) $ — Gains (losses) on fair value hedging relationships Gains (losses) on hedged items $ — $ (326) $ — Gains on interest rate swaps — 434 — Total gains on fair value hedging relationships $ — $ 108 $ — For the Nine Months Ended September 30, 2019 Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded $ (1,194) $ (721) $ 73 The effects of cash flow and fair value hedging Gains on cash flow hedging relationship Amounts reclassified from OCI into earnings $ 3 $ 4 $ — Gains (losses) on fair value hedging relationship Gains (losses) on hedged items $ — $ (160) $ — Gains on interest rate swaps — 128 — Total gains (losses) on fair value hedging relationships $ — $ (32) $ —

Segment Disclosures (Tables)

Segment Disclosures (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Schedule of Segment Disclosures	The following table presents segment data (dollars in millions): Direct Payment Total 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 91 — 91 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 For the Three Months Ended September 30, 2019 Interest income Credit card loans $ 2,465 $ — $ 2,465 Private student loans 204 — 204 Personal loans 249 — 249 Other 122 — 122 Total interest income 3,040 — 3,040 Interest expense 638 — 638 Net interest income 2,402 — 2,402 Provision for credit losses (1) 799 — 799 Other income 409 89 498 Other expense 1,069 38 1,107 Income before income taxes $ 943 $ 51 $ 994 (1) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach. The following table presents segment data (dollars in millions): Direct Payment Total 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 284 — 284 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 For the Nine Months Ended September 30, 2019 Interest income Credit card loans $ 7,223 $ — $ 7,223 Private student loans 612 — 612 Personal loans 727 — 727 Other 391 1 392 Total interest income 8,953 1 8,954 Interest expense 1,915 — 1,915 Net interest income 7,038 1 7,039 Provision for credit losses (1) 2,395 — 2,395 Other income 1,217 259 1,476 Other expense 3,097 112 3,209 Income before income tax expense $ 2,763 $ 148 $ 2,911 (1) Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	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): Direct Banking Payment Services Total 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 For the Three Months Ended September 30, 2019 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 238 $ 17 $ 255 Protection products revenue 48 — 48 Transaction processing revenue — 52 52 Other income 3 20 23 Total other income subject to ASC 606 (2) 289 89 378 Other income not subject to ASC 606 Loan fee income 120 — 120 Total other income not subject to ASC 606 120 — 120 Total other income by operating segment $ 409 $ 89 $ 498 (1) Net of rewards, including Cashback Bonus rewards, of $514 million and $520 million for the three months ended September 30, 2020 and 2019, respectively. (2) Excludes $1 million of deposit product fees that are reported within net interest income for the three months ended September 30, 2020. Deposit product fees were immaterial for the three months ended September 30, 2019. 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): Direct Banking Payment Services Total 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 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 For the Nine Months Ended September 30, 2019 Other income subject to ASC 606 Discount and interchange revenue, net (1) $ 738 $ 47 $ 785 Protection products revenue 146 — 146 Transaction processing revenue — 146 146 Other income 7 66 73 Total other income subject to ASC 606 (2) 891 259 1,150 Other income not subject to ASC 606 Loan fee income 326 — 326 Total other income not subject to ASC 606 326 — 326 Total other income by operating segment $ 1,217 $ 259 $ 1,476 (1) Net of rewards, including Cashback Bonus rewards, of $1.4 billion for the nine months ended September 30, 2020 and 2019. (2) Excludes $2 million of deposit product fees that are reported within net interest income for the nine months ended September 30, 2020 and 2019.

Background and Basis of Prese_3

Background and Basis of Presentation (Narrative) (Details) $ in Millions

9 Months Ended

Sep. 30, 2020USD ($)segment

Jun. 30, 2020USD ($)

Jan. 01, 2020USD ($)

Dec. 31, 2019USD ($)

Sep. 30, 2019USD ($)

[3]

Jun. 30, 2019USD ($)

[3]

Dec. 31, 2018USD ($)

[3]

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Number of reportable segments (in number of segments) | segment

2

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Allowance for credit losses

$ 8,226

[1],[2]

$ 8,184

$ 5,844

$ 3,383

[2],[3]

$ 3,299

$ 3,202

$ 3,041

Other assets

3,453

2,459

Retained earnings

$ 19,292

$ 21,290

Accounting Standards Update 2016-13 [Member]

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Allowance for credit losses

2,500

Other assets

600

Retained earnings

$ (1,900)

[1]

Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[2]

Prior to adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[3]

Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Investments (Narrative) (Detail

Investments (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Investments, Debt and Equity Securities [Abstract]
Securities Loaned	$ 11,400,000,000		$ 11,400,000,000
Securities Received as Collateral	$ 11,600,000,000		$ 11,600,000,000
dfs_FairValueAboveUSTBillsLent	1.02		1.02
Collateral Securities Repledged, Delivered, or Used	$ 0		$ 0
Investment Holdings [Line Items]
Proceeds from sales of available-for-sale securities	0	$ 0	0	$ 0
Recognized gains (losses) on available-for-sale securities	0	$ 0	0	$ 0
Affordable housing project equity method investments	292,000,000		292,000,000		$ 298,000,000
Contingent liabilities related to affordable housing project equity method investments	45,000,000		45,000,000		59,000,000
Payment Services [Member]
Investment Holdings [Line Items]
Equity securities without readily determinable fair value	35,000,000		35,000,000		42,000,000
Other Assets [Member] | Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Equity method investments	323,000,000		323,000,000		336,000,000
Other Liabilities [Member] | Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Contingent liabilities related to equity method investments	$ 61,000,000		$ 61,000,000		$ 74,000,000

Investments (Schedule of Invest

Investments (Schedule of Investment Securities) (Details) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Other short-term investments	[1]	$ 8,048	$ 0
Investment securities	[1]	20,854	10,595
US Treasury Bill Securities [Member] | Asset Pledged as Collateral [Member]
Investment Holdings [Line Items]
Other short-term investments		5,909	0
US Treasury Bill Securities [Member] | Asset Not Pledged as Collateral [Member]
Investment Holdings [Line Items]
Other short-term investments	[2]	2,139	0
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Investment securities		9,548	9,906
U.S. Treasury Securities [Member] | dfs_USTreasurySecuritiesMemberNonSept2020SLT [Member]
Investment Holdings [Line Items]
Derivative collateral		135	121
U.S. Treasury Securities [Member] | Asset Pledged as Collateral [Member]
Investment Holdings [Line Items]
Investment securities	[3]	5,618	121
U.S. Treasury Securities [Member] | Asset Not Pledged as Collateral [Member]
Investment Holdings [Line Items]
Investment securities		3,930	9,785
Residential Mortgage-Backed Securities - Agency [Member]
Investment Holdings [Line Items]
Investment securities	[4]	$ 11,306	$ 689
[1]	Includes amounts related to a securities lending transaction in September 2020. See Note 2: Investments for additional information.
[2]	(1) Includes U.S. Treasury bills with maturity dates greater than 90 days but less than one year at the time of acquisition.
[3]	As of September 30, 2020 and December 31, 2019, includes $135 million and $121 million, respectively, of U.S. Treasury securities pledged as swap collateral other than amounts associated with the September 2020 securities lending transaction.
[4]	Consists of residential mortgage-backed securities issued by Fannie Mae, Freddie Mac and Ginnie Mae.

Investments (Schedule of Amorti

Investments (Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value) (Details) - USD ($) $ in Millions		Sep. 30, 2020		Dec. 31, 2019
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]	$ 20,148		$ 10,173
Available-for-sale investment securities, gross unrealized gains	[1]	425		158
Available-for-sale investment securities, gross unrealized losses	[1]	0		(8)
Available-for-sale investment securities, fair value	[1]	20,573		10,323
Held-to-maturity investment securities, amortized cost	[2]	281		272
Held-to-maturity investment securities, gross unrealized gains	[2]	9		3
Held-to-maturity investment securities, gross unrealized losses	[2]	0		(1)
Held-to-maturity investment securities, fair value	[2]	290		274
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]	9,134		9,759
Available-for-sale investment securities, gross unrealized gains	[1]	414		155
Available-for-sale investment securities, gross unrealized losses	[1]	0		(8)
Available-for-sale investment securities, fair value	[1]	9,548		9,906
Residential Mortgage-Backed Securities - Agency [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, amortized cost	[1]	11,014	[3]	414
Available-for-sale investment securities, gross unrealized gains	[1]	11		3
Available-for-sale investment securities, gross unrealized losses	[1]	0		0
Available-for-sale investment securities, fair value	[1]	11,025	[3]	417
Held-to-maturity investment securities, amortized cost	[2],[4]	281	[3]	272
Held-to-maturity investment securities, gross unrealized gains	[2],[4]	9		3
Held-to-maturity investment securities, gross unrealized losses	[2],[4]	0		(1)
Held-to-maturity investment securities, fair value	[2],[4]	$ 290	[3]	$ 274
[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 residential mortgage-backed securities are reflective of the contractual maturities of the investment.
[4]	Amounts represent residential mortgage-backed securities 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 Fair V

Investments (Schedule of Fair Value of Securities in a Continuous Unrealized Loss Position for Less Than 12 Months and More Than 12 Months) (Details) - U.S. Treasury Securities [Member] $ in Millions	Dec. 31, 2019USD ($)securities
Investment Holdings [Line Items]
Available-for-sale investment securities, continuous unrealized loss position, number of securities | securities	11
Available-for-sale investment securities, continuous unrealized loss position, less than 12 months, fair value	$ 1,402
Available-for-sale investment securities, continuous unrealized loss position, less than 12 months, unrealized losses	(8)
Available-for-sale investment securities, continuous unrealized loss position, more than 12 months, fair value	0
Available-for-sale investment securities, continuous unrealized loss position, more than 12 months, unrealized losses	$ 0

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, 2020		Dec. 31, 2019
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost		$ 1,880
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost		7,308
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost		291
Available-for-sale investment securities, debt maturities, after ten years, amortized cost		10,669
Available-for-sale investment securities, amortized cost	[1]	20,148		$ 10,173
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		281
Held-to-maturity investment securities, amortized cost	[2]	281		272
Available-for-sale investment securities, debt maturities, one year or less, fair value		1,900
Available-for-sale investment securities, debt maturities, after one year through five years, fair value		7,704
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value		300
Available-for-sale investment securities, debt maturities, after ten years, fair value		10,669
Available-for-sale investment securities, fair value	[1]	20,573		10,323
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		290
Held-to-maturity investment securities, fair value	[2]	290		274
U.S. Treasury Securities [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost		1,880
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost		7,254
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost		0
Available-for-sale investment securities, debt maturities, after ten years, amortized cost		0
Available-for-sale investment securities, amortized cost	[1]	9,134		9,759
Available-for-sale investment securities, debt maturities, one year or less, fair value		1,900
Available-for-sale investment securities, debt maturities, after one year through five years, fair value		7,648
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value		0
Available-for-sale investment securities, debt maturities, after ten years, fair value		0
Available-for-sale investment securities, fair value	[1]	9,548		9,906
Residential Mortgage-Backed Securities - Agency [Member]
Investment Holdings [Line Items]
Available-for-sale investment securities, debt maturities, one year or less, amortized cost	[3]	0
Available-for-sale investment securities, debt maturities, after one year through five years, amortized cost	[3]	54
Available-for-sale investment securities, debt maturities, after five years through ten years, amortized cost	[3]	291
Available-for-sale investment securities, debt maturities, after ten years, amortized cost	[3]	10,669
Available-for-sale investment securities, amortized cost	[1]	11,014	[3]	414
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]	281
Held-to-maturity investment securities, amortized cost	[2],[4]	281	[3]	272
Available-for-sale investment securities, debt maturities, one year or less, fair value	[3]	0
Available-for-sale investment securities, debt maturities, after one year through five years, fair value	[3]	56
Available-for-sale investment securities, debt maturities, after five years through ten years, fair value	[3]	300
Available-for-sale investment securities, debt maturities, after ten years, fair value	[3]	10,669
Available-for-sale investment securities, fair value	[1]	11,025	[3]	417
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]	290
Held-to-maturity investment securities, fair value	[2],[4]	$ 290	[3]	$ 274
[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 residential mortgage-backed securities are reflective of the contractual maturities of the investment.
[4]	Amounts represent residential mortgage-backed securities 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	Mar. 31, 2020	Jan. 01, 2020USD ($)	Sep. 30, 2020USD ($)		Sep. 30, 2019USD ($)		Sep. 30, 2020USD ($)		Sep. 30, 2020USD ($)segment		Sep. 30, 2019USD ($)		Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)		Jun. 30, 2019USD ($)	[3]	Dec. 31, 2018USD ($)	[3]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan portfolio segments (in segments) | segment									2
Allowance for credit losses		$ 5,844	$ 8,226	[1],[2]	$ 3,299	[3]	$ 8,226	[1],[2]	$ 8,226	[1],[2]	$ 3,299	[3]	$ 8,184	$ 3,383	[2],[3]	$ 3,202		$ 3,041
Allowance for credit losses, period increase (decrease)							$ 2,300		$ 4,800
Expected Future Unemployment Rate			11.00%				11.00%		11.00%
Reasonable and supportable forecast period	12 months	18 months
Reversion period									12 months
Private student loans in repayment			$ 5,300				$ 5,300		$ 5,300					5,600
Private student loans in forbearance			$ 64				64		$ 64					46
Percentage of defaulted loans that were charged off at the end of the month in which they defaulted (in percent)			65.00%		37.00%				52.00%		38.00%
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 temporary modification programs (in years)									9 years
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		$ 4,550	$ 6,491		$ 2,799	[3]	$ 6,491		$ 6,491		$ 2,799	[3]	$ 6,491	$ 2,883	[3]	$ 2,691		$ 2,528
Maximum period of payment reduction for the temporary reduced payment program (in months)									12 months
Permanent workout program maturity (in months)									60 months
Interest and fees forgiven due to credit card loan modification program			$ 13		$ 19				$ 52		$ 53
Accounting Standards Update 2016-13 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses		2,500
Allowance for credit losses, period increase (decrease)		$ 2,500
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[3]	Prior to adoption of 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, 2020		Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019		Sep. 30, 2019	[3]	Jun. 30, 2019	[3]	Dec. 31, 2018	[3]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		$ 88,660				$ 95,894
Allowance for Credit Losses		(8,226)	[1],[2]	$ (8,184)	$ (5,844)	(3,383)	[2],[3]	$ (3,299)		$ (3,202)		$ (3,041)
Net loan receivables		80,434				92,511
Accounting Standards Update 2016-13 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Credit Losses					(2,500)
Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		27,287				31,840
Allowance for Credit Losses	[4]	(1,964)				(1,179)
Credit Card Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[5]	27,026				31,548
Allowance for Credit Losses	[5],[6]	(1,964)				(1,179)
Net loan receivables		25,062				30,369
Seller's interest		11,627				12,652
Student Loan Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		261				292
Credit Card Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[7],[8]	69,656				77,181
Allowance for Credit Losses		(6,491)		(6,491)	(4,550)	(2,883)	[3]	(2,799)		(2,691)		(2,528)
Accrued interest receivable		380				471
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		15,400				18,900
Seller's interest		11,600				12,700
Total Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9]	19,004				18,713
Total Other Loans [Member] | Private Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9],[10]	10,016				9,653
Allowance for Credit Losses		(840)		(799)	(653)	(148)	[3]	(147)		(167)		(169)
Accrued interest receivable		527				461
Total Other Loans [Member] | Private Student Loans [Member] | Student Loan Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral		261				292
Total Other Loans [Member] | Personal Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9]	7,211				7,687
Allowance for Credit Losses		(857)		(857)	(613)	(348)	[3]	(348)		(338)		(338)
Accrued interest receivable		47				53
Total Other Loans [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9]	1,777				1,373
Allowance for Credit Losses		(38)		$ (37)	$ (28)	(4)	[3]	$ (5)		$ (6)		$ (6)
Accrued interest receivable		$ 6				$ 4
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[3]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[4]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[5]	The Company maintains its allowance for credit losses at an amount sufficient to absorb expected losses inherent in all loan receivables, which includes all loan receivables in the trusts. Therefore, credit risk associated with the transferred receivables is fully reflected on the Company's balance sheet in accordance with GAAP.
[6]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[7]	Amounts include carrying values of $15.4 billion and $18.9 billion underlying investors' interest in trust debt at September 30, 2020 and December 31, 2019, respectively, and $11.6 billion and $12.7 billion in seller's interest at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information.
[8]	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 $380 million and $471 million at September 30, 2020 and December 31, 2019, respectively.
[9]	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 $527 million, $47 million and $6 million, respectively, at September 30, 2020 and $461 million, $53 million and $4 million, respectively, at December 31, 2019.
[10]	Amounts include carrying values of $261 million and $292 million in loans pledged as collateral against the note issued from a student loan securitization trust at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and 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, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		$ 88,660	$ 95,894
Revolving line-of-credit arrangements that were converted to term loans as a result of a TDR program, ending balance		1,000	956
Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[1],[2]	69,656	77,181
Credit Card Loans [Member] | FICO Score, 660 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card	[3]	$ 57,148	$ 61,997
FICO distribution %, credit card	[3]	82.00%	80.00%
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]	$ 12,508	$ 15,184
FICO distribution %, credit card	[3]	18.00%	20.00%
Total Other Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[4]	$ 19,004	$ 18,713
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[4],[5]	10,016	9,653
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 2020	[6],[7]	$ 983
FICO distribution %, originated in 2020	[6],[7]	97.00%
Loan receivables, originated in 2019	[6],[7]	$ 1,690	$ 1,176
FICO distribution %, originated in 2019	[6],[7]	97.00%	93.00%
Loan receivables, originated in 2018	[6],[7]	$ 1,399	$ 1,518
FICO distribution %, originated in 2018	[6],[7]	96.00%	95.00%
Loan receivables, originated in 2017	[6],[7]	$ 1,076	$ 1,198
FICO distribution %, originated in 2017	[6],[7]	95.00%	95.00%
Loan receivables, originated in 2016	[6],[7]	$ 817	$ 934
FICO distribution %, originated in 2016	[6],[7]	94.00%	94.00%
Loan receivables, originated prior to 2016	[6],[7]	$ 3,586	$ 4,229
FICO distribution %, originated prior to 2016	[6],[7]	94.00%	93.00%
Loan receivables	[6],[7]	$ 9,551	$ 9,055
FICO distribution %, loan receivables	[6],[7]	95.00%	94.00%
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 2020	[6],[7]	$ 29
FICO distribution %, originated in 2020	[6],[7]	3.00%
Loan receivables, originated in 2019	[6],[7]	$ 57	$ 92
FICO distribution %, originated in 2019	[6],[7]	3.00%	7.00%
Loan receivables, originated in 2018	[6],[7]	$ 60	$ 79
FICO distribution %, originated in 2018	[6],[7]	4.00%	5.00%
Loan receivables, originated in 2017	[6],[7]	$ 57	$ 69
FICO distribution %, originated in 2017	[6],[7]	5.00%	5.00%
Loan receivables, originated in 2016	[6],[7]	$ 48	$ 58
FICO distribution %, originated in 2016	[6],[7]	6.00%	6.00%
Loan receivables, originated prior to 2016	[6],[7]	$ 214	$ 300
FICO distribution %, originated prior to 2016	[6],[7]	6.00%	7.00%
Loan receivables	[6],[7]	$ 465	$ 598
FICO distribution %, loan receivables	[6],[7]	5.00%	6.00%
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[4]	$ 7,211	$ 7,687
Total Other Loans [Member] | Personal Loans [Member] | FICO Score, 660 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2020		$ 2,175
FICO distribution %, originated in 2020		99.00%
Loan receivables, originated in 2019		$ 2,506	$ 3,529
FICO distribution %, originated in 2019		97.00%	98.00%
Loan receivables, originated in 2018		$ 1,221	$ 1,941
FICO distribution %, originated in 2018		92.00%	93.00%
Loan receivables, originated in 2017		$ 680	$ 1,167
FICO distribution %, originated in 2017		89.00%	90.00%
Loan receivables, originated in 2016		$ 242	$ 475
FICO distribution %, originated in 2016		88.00%	88.00%
Loan receivables, originated prior to 2016		$ 55	$ 145
FICO distribution %, originated prior to 2016		82.00%	84.00%
Loan receivables		$ 6,879	$ 7,257
FICO distribution %, loan receivables		95.00%	94.00%
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 2020		$ 15
FICO distribution %, originated in 2020		1.00%
Loan receivables, originated in 2019		$ 89	$ 62
FICO distribution %, originated in 2019		3.00%	2.00%
Loan receivables, originated in 2018		$ 101	$ 140
FICO distribution %, originated in 2018		8.00%	7.00%
Loan receivables, originated in 2017		$ 81	$ 136
FICO distribution %, originated in 2017		11.00%	10.00%
Loan receivables, originated in 2016		$ 34	$ 65
FICO distribution %, originated in 2016		12.00%	12.00%
Loan receivables, originated prior to 2016		$ 12	$ 27
FICO distribution %, originated prior to 2016		18.00%	16.00%
Loan receivables		$ 332	$ 430
FICO distribution %, loan receivables		5.00%	6.00%
[1]	Amounts include carrying values of $15.4 billion and $18.9 billion underlying investors' interest in trust debt at September 30, 2020 and December 31, 2019, respectively, and $11.6 billion and $12.7 billion in seller's interest at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and 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 $380 million and $471 million at September 30, 2020 and December 31, 2019, respectively.
[3]	Amounts include $1.0 billion and $956 million of revolving line-of-credit arrangements that were converted to term loans as a result of a TDR program as of September 30, 2020 and December 31, 2019, 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 $527 million, $47 million and $6 million, respectively, at September 30, 2020 and $461 million, $53 million and $4 million, respectively, at December 31, 2019.
[5]	Amounts include carrying values of $261 million and $292 million in loans pledged as collateral against the note issued from a student loan securitization trust at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information.
[6]	A majority of student loans 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, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables		$ 88,660	$ 95,894
Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[1],[2]	69,656	77,181
Total Other Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[3]	19,004	18,713
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[3],[4]	10,016	9,653
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables	[3]	7,211	7,687
30-89 Days Delinquent [Member] | Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card		678	999
30-89 Days Delinquent [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2020	[5],[6]	0
Loan receivables, originated in 2019	[5],[6]	3	1
Loan receivables, originated in 2018	[5],[6]	11	4
Loan receivables, originated in 2017	[5],[6]	13	11
Loan receivables, originated in 2016	[5],[6]	14	14
Loan receivables, originated prior to 2016	[5],[6]	76	106
Loan receivables	[5],[6]	117	136
30-89 Days Delinquent [Member] | Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2020		4
Loan receivables, originated in 2019		19	11
Loan receivables, originated in 2018		17	27
Loan receivables, originated in 2017		11	22
Loan receivables, originated in 2016		4	10
Loan receivables, originated prior to 2016		1	4
Loan receivables		56	74
90 or More Days Delinquent [Member] | Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card		650	1,020
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 2020	[5],[6]	0
Loan receivables, originated in 2019	[5],[6]	0	0
Loan receivables, originated in 2018	[5],[6]	3	1
Loan receivables, originated in 2017	[5],[6]	4	2
Loan receivables, originated in 2016	[5],[6]	4	5
Loan receivables, originated prior to 2016	[5],[6]	21	37
Loan receivables	[5],[6]	32	45
90 or More Days Delinquent [Member] | Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2020		1
Loan receivables, originated in 2019		7	3
Loan receivables, originated in 2018		7	11
Loan receivables, originated in 2017		5	10
Loan receivables, originated in 2016		2	5
Loan receivables, originated prior to 2016		1	2
Loan receivables		23	31
30 or More Days Delinquent [Member] | Credit Card Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, credit card		1,328	2,019
30 or More Days Delinquent [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2020	[5],[6]	0
Loan receivables, originated in 2019	[5],[6]	3	1
Loan receivables, originated in 2018	[5],[6]	14	5
Loan receivables, originated in 2017	[5],[6]	17	13
Loan receivables, originated in 2016	[5],[6]	18	19
Loan receivables, originated prior to 2016	[5],[6]	97	143
Loan receivables	[5],[6]	149	181
30 or More Days Delinquent [Member] | Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan receivables, originated in 2020		5
Loan receivables, originated in 2019		26	14
Loan receivables, originated in 2018		24	38
Loan receivables, originated in 2017		16	32
Loan receivables, originated in 2016		6	15
Loan receivables, originated prior to 2016		2	6
Loan receivables		$ 79	$ 105
[1]	Amounts include carrying values of $15.4 billion and $18.9 billion underlying investors' interest in trust debt at September 30, 2020 and December 31, 2019, respectively, and $11.6 billion and $12.7 billion in seller's interest at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and 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 $380 million and $471 million at September 30, 2020 and December 31, 2019, 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 $527 million, $47 million and $6 million, respectively, at September 30, 2020 and $461 million, $53 million and $4 million, respectively, at December 31, 2019.
[4]	Amounts include carrying values of $261 million and $292 million in loans pledged as collateral against the note issued from a student loan securitization trust at September 30, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information.
[5]	Includes PCD loans for all periods presented.
[6]	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, 2020		Sep. 30, 2019		Sep. 30, 2020		Sep. 30, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		$ 3,383	[1],[2]	$ 8,184		$ 3,202	[1]	$ 3,383	[1],[2]	$ 3,041	[1]
Cumulative effect of ASU No. 2016-13 adoption		2,461	[3]					1,902
Provision for credit losses				710	[4]	799	[1]	4,586	[4]	2,395	[1]
Charge-offs				(842)		(891)		(2,767)		(2,676)
Recoveries				174		189		563		541
Net charge-offs				(668)		(702)	[5]	(2,204)		(2,135)	[5]
Other	[6]									(2)
Allowance for credit losses, balance at end of period		5,844		8,226	[2],[7]	3,299	[1]	8,226	[2],[7]	3,299	[1]
Credit loss build (release) on unfunded commitments				40				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]	6,491		2,691	[1]	2,883	[1]	2,528	[1]
Cumulative effect of ASU No. 2016-13 adoption	[3]	1,667
Provision for credit losses				604	[4]	719	[1]	3,916	[4]	2,121	[1]
Charge-offs				(759)		(784)		(2,480)		(2,347)
Recoveries				155		173		505		497
Net charge-offs				(604)		(611)	[5]	(1,975)		(1,850)	[5]
Other										0
Allowance for credit losses, balance at end of period		4,550		6,491		2,799	[1]	6,491		2,799	[1]
Total Other Loans [Member] | Student Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, balance at beginning of period		148	[1]	799		167	[1]	148	[1]	169	[1]
Cumulative effect of ASU No. 2016-13 adoption	[3]	505
Provision for credit losses				55	[4]	6	[1]	233	[4]	24	[1]
Charge-offs				(20)		(17)		(62)		(54)
Recoveries				6		3		16		10
Net charge-offs				(14)		(14)	[5]	(46)		(44)	[5]
Other	[6]									(2)
Allowance for credit losses, balance at end of period		653		840		147	[1]	840		147	[1]
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]	857		338	[1]	348	[1]	338	[1]
Cumulative effect of ASU No. 2016-13 adoption	[3]	265
Provision for credit losses				49	[4]	86	[1]	426	[4]	250	[1]
Charge-offs				(62)		(89)		(224)		(274)
Recoveries				13		13		42		34
Net charge-offs				(49)		(76)	[5]	(182)		(240)	[5]
Other										0
Allowance for credit losses, balance at end of period		613		857		348	[1]	857		348	[1]
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]	37		6	[1]	4	[1]	6	[1]
Cumulative effect of ASU No. 2016-13 adoption	[3]	24
Provision for credit losses				2	[4]	0	[1]	11	[4]	0	[1]
Charge-offs				(1)		(1)		(1)		(1)
Recoveries				0		0		0		0
Net charge-offs				(1)		(1)	[5]	(1)		(1)	[5]
Other										0
Allowance for credit losses, balance at end of period		$ 28		$ 38		$ 5	[1]	$ 38		$ 5	[1]
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to 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 allowance for credit losses as a result of adoption of ASU No. 2016-13 on January 1, 2020.
[4]	Excludes a $40 million build and $17 million build of the liability for expected credit losses on unfunded commitments for the three months and nine months ended September 30, 2020, respectively, as the liability is recorded in accrued expenses and other liabilities in the Company's condensed consolidated statements of financial condition.
[5]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, net charge-offs on PCD loans generally did not result in a charge to earnings.
[6]	Net change in reserves on PCD pools having no remaining non-accretable difference (prior to adoption of ASU No. 2016-13 on January 1, 2020).
[7]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Receivables [Abstract]
Interest and fees accrued subsequently charged off, net of recoveries (recorded as a reduction of interest income)	$ 114	$ 127	$ 393	$ 382
Fees accrued subsequently charged off, net of recoveries (recorded as a reduction to other income)	$ 27	$ 29	$ 95	$ 90

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		$ 1,567		$ 1,567		$ 2,312
Loan receivables, 90 or more days delinquent and accruing		657		657		1,014
Loan receivables, total non-accruing	[1]	228		228		266
30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		859		859		1,214
90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		708		708		1,098
Credit Card Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		1,328		1,328		2,019
Loan receivables, 90 or more days delinquent and accruing		604		604		940
Loan receivables, total non-accruing	[1]	196		196		237
Estimated gross interest income that would have been recorded based on original terms		7	$ 12	25	$ 34
Credit Card Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		678		678		999
Credit Card Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		650		650		1,020
Total Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		239		239		293
Loan receivables, 90 or more days delinquent and accruing		53		53		74
Loan receivables, total non-accruing	[1]	32		32		29
Total Other Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		181		181		215
Total Other Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		58		58		78
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due	[2]	149		149		181
Loan receivables, 90 or more days delinquent and accruing	[2]	31		31		45
Loan receivables, total non-accruing	[1],[2]	12		12		11
Total Other Loans [Member] | Private Student Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due	[2]	117		117		136
Total Other Loans [Member] | Private Student Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due	[2]	32		32		45
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		79		79		105
Loan receivables, 90 or more days delinquent and accruing		22		22		29
Loan receivables, total non-accruing	[1]	9		9		12
Total Other Loans [Member] | Personal Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		56		56		74
Total Other Loans [Member] | Personal Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		23		23		31
Total Other Loans [Member] | Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		11		11		7
Loan receivables, 90 or more days delinquent and accruing		0		0		0
Loan receivables, total non-accruing	[1]	11		11		6
Total Other Loans [Member] | Other Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		8		8		5
Total Other Loans [Member] | Other Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		$ 3		$ 3		$ 2
[1]	The Company estimates that the gross interest income that would have been recorded in accordance with the original terms of non-accruing credit card loans was $7 million and $12 million for the three months ended September 30, 2020 and 2019, respectively, and $25 million and $34 million for the nine months ended September 30, 2020 and 2019, respectively. The Company does not separately track the amount of gross interest income that would have been recorded in accordance with the original terms of loans. This amount was estimated based on customers' current balances and most recent interest rates.
[2]	Includes PCD loans for all periods presented.

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, 2020USD ($)accounts	Sep. 30, 2019USD ($)accounts	Sep. 30, 2020USD ($)accounts	Sep. 30, 2019USD ($)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]	20,779	97,046	130,869	273,970
Accounts that entered a TDR program during the period, balances	[1]	$ 150	$ 623	$ 875	$ 1,766
Accounts that entered a TDR program during the period and were converted from revolving line-of-credit arrangements to term loans, balances		$ 143	$ 173	$ 529	$ 336
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		118	1,692	1,767	4,978
Accounts that entered a TDR program during the period, balances		$ 2	$ 31	$ 32	$ 92
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		2,505	2,859	6,315	8,129
Accounts that entered a TDR program during the period, balances		$ 33	$ 39	$ 83	$ 110
[1]	Accounts that entered a credit card TDR program include $143 million and $173 million that were converted from revolving line-of-credit arrangements to term loans during the three months ended September 30, 2020 and 2019, respectively, and $529 million and $336 million for the nine months ended September 30, 2020 and 2019, 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, 2020USD ($)accounts	Sep. 30, 2019USD ($)accounts	Sep. 30, 2020USD ($)accountsmissed_payments	Sep. 30, 2019USD ($)accounts
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amount of missed payments after which a customer defaults from a TDR program (in payments) | missed_payments				2
Credit Card Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivables Modifications Entering Program, Converted from Revolving Line-of-Credit Arrangement to Term Loan		$ 143	$ 173	$ 529	$ 336
Interest and fees forgiven due to loan modification program		$ 13	$ 19	$ 52	$ 53
TDRs that subsequently defaulted, number of accounts (in accounts) | accounts	[1],[2]	8,983	19,108	41,285	50,980
TDRs that subsequently defaulted, aggregated outstanding balances upon default	[1],[2]	$ 52	$ 109	$ 235	$ 294
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]	272	396	876	966
TDRs that subsequently defaulted, aggregated outstanding balances upon default	[3]	$ 6	$ 8	$ 18	$ 19
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]	624	1,131	2,446	2,925
TDRs that subsequently defaulted, aggregated outstanding balances upon default	[1]	$ 9	$ 15	$ 36	$ 42
[1]	For credit card loans and personal loans, a customer defaults from a TDR program after two consecutive missed payments. The outstanding balance upon default is generally the loan balance at the end of the month prior to default.
[2]	Terms revert back to the pre-modification terms for customers who default from a temporary program and charging privileges remain suspended in most cases.
[3]	For student loans, defaults have been defined as loans that 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 Student Loan _3

Credit Card and Student Loan Securitization Activities (Narrative) (Details) - Variable Interest Entity, Primary Beneficiary [Member]	9 Months Ended
	Sep. 30, 2020trustclasses
Student Loan Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Number of trusts issuing securities	1
Number of trusts	2
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) | classes	4

Credit Card and Student Loan _4

Credit Card and Student Loan Securitization Activities (Schedule of Restricted Credit Card Securitized Assets) (Details) - USD ($) $ in Millions		Sep. 30, 2020		Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019	[3]	Dec. 31, 2018	[3]
Variable Interest Entity [Line Items]
Restricted cash		$ 576				$ 40		$ 37
Loan receivables		88,660				95,894
Allowance for credit losses allocated to securitized loan receivables		(8,226)	[1],[2]	$ (8,184)	$ (5,844)	(3,383)	[2],[3]	$ (3,299)	[3]	$ (3,202)		$ (3,041)
Net loan receivables		80,434				92,511
Other		3,453				2,459
Total assets		124,349				113,996
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash		576				40
Loan receivables		27,287				31,840
Allowance for credit losses allocated to securitized loan receivables	[4]	(1,964)				(1,179)
Other		6				5
Variable Interest Entity, Primary Beneficiary [Member] | Credit Card Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Restricted cash		567				28
Investors' interests held by third-party investors		11,150				14,100
Investors' interests held by wholly-owned subsidiaries of Discover Bank		4,249				4,796
Seller's interest		11,627				12,652
Loan receivables	[5]	27,026				31,548
Allowance for credit losses allocated to securitized loan receivables	[5],[6]	(1,964)				(1,179)
Net loan receivables		25,062				30,369
Other		4				5
Total assets		$ 25,633				$ 30,402
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[3]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[4]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[5]	The Company maintains its allowance for credit losses at an amount sufficient to absorb expected losses inherent in all loan receivables, which includes all loan receivables in the trusts. Therefore, credit risk associated with the transferred receivables is fully reflected on the Company's balance sheet in accordance with GAAP.
[6]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

Credit Card and Student Loan _5

Credit Card and Student Loan Securitization Activities (Schedule of Restricted Student Loan Securitized Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Variable Interest Entity [Line Items]
Restricted cash	$ 576	$ 40	$ 37
Loan receivables	88,660	95,894
Total assets	124,349	113,996
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash	576	40
Loan receivables	27,287	31,840
Variable Interest Entity, Primary Beneficiary [Member] | Student Loan Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Restricted cash	9	12
Loan receivables	261	292
Total assets	$ 270	$ 304

Intangible Assets (Details)

Intangible Assets (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, net	$ 95,000,000		$ 95,000,000	$ 155,000,000
Goodwill, Impairment Loss	0		0
Trade Names [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets Acquired		$ 36,000,000	0
Intangible assets, net	92,000,000		92,000,000
International Transaction Processing Rights [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets Acquired		$ 23,000,000
Intangible assets, net	$ 0		$ 0

Deposits (Narrative) (Details)

Deposits (Narrative) (Details)	9 Months Ended
	Sep. 30, 2020channels
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, 2020	Dec. 31, 2019
Deposits [Abstract]
Certificates of deposit in amounts less than $100,000		$ 21,071	$ 25,113
Certificates of deposit in amounts $100,000 or greater	[1]	9,771	9,268
Savings deposits, including money market deposit accounts		46,096	37,574
Total interest-bearing deposits		76,938	71,955
Certificates of deposit equal to or greater than $250,000		$ 2,800	$ 2,600
[1]	Includes $2.8 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, 2020 and December 31, 2019, respectively.

Deposits (Schedule of $100,000

Deposits (Schedule of $100,000 or More Certificates of Deposit Maturities) (Details) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Deposits [Abstract]
Three months or less		$ 1,734
Over three months through six months		2,375
Over six months through twelve months		3,166
Over twelve months		2,496
Total	[1]	$ 9,771	$ 9,268
[1]	Includes $2.8 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, 2020 and December 31, 2019, respectively.

Deposits (Schedule of Certifica

Deposits (Schedule of Certificates of Deposit Maturities) (Details) $ in Millions	Sep. 30, 2020USD ($)
Deposits [Abstract]
2020	$ 4,861
Time Deposit Maturities, Year One	0
2021	15,825
2022	4,353
2023	2,214
2024	1,357
Thereafter	2,232
Total	$ 30,842

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, 2020USD ($)
Debt Instrument [Line Items]
Total commitment of secured credit facilities	$ 6
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, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		$ 21,841	$ 25,701
2021		0
Variable Interest Entity, Primary Beneficiary [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		11,425	14,284
Securitized Debt [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		11,425	14,284
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member]
Debt Instrument [Line Items]
Long-term borrowings (in dollars)		$ 11,289	14,124
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		2.70%
Long-term borrowings (in dollars)	[1]	$ 6,621	8,609
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		1.85%
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		3.32%
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		0.55%
Long-term borrowings (in dollars)	[2]	$ 4,668	5,515
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		0.38%
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		0.75%
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 + 23 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		0.23%
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)		$ 136	160
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member]
Debt Instrument [Line Items]
Interest rate		4.25%
Weighted-average interest rate		4.25%
Long-term borrowings (in dollars)	[3],[4]	$ 136	160
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%
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)		$ 3,327	3,296
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		3.73%
Long-term borrowings (in dollars)		$ 336	340
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		4.60%
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		3.89%
Long-term borrowings (in dollars)	[1]	$ 6,236	6,785
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate		2.45%
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate		4.65%
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		4.68%
Long-term borrowings (in dollars)		$ 517	$ 996
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate		4.68%
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate		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 LIBOR or Overnight Index Swap ("OIS") Rate. Use of these interest rate swaps impacts carrying value of the debt. See Note 16: Derivatives and Hedging Activities.
[2]	Discover Card Execution Note Trust floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month LIBOR + 23 to 60 basis points as of September 30, 2020.
[3]	Repayment of this debt is dependent upon the timing of principal and interest payments on the underlying student loans. The date shown represents final maturity date.
[4]	The 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, 2020.

Long-Term Borrowings (Schedul_2

Long-Term Borrowings (Schedule of Long-Term Borrowings Maturities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2020	$ 550
2021	4,232
2022	5,204
2023	3,411
2024	2,630
Thereafter	5,814
Total	$ 21,841	$ 25,701

Preferred Stock (Details)

Preferred Stock (Details) - USD ($)	Jun. 22, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Preferred Stock, Par or Stated Value Per Share		$ 0.01		$ 0.01
Proceeds from issuance of preferred stock		$ 493,000,000	$ 0
Preferred Stock, Redemption Amount	$ 1,000
Preferred Stock, Dividend Rate, Percentage	612.50%
Preferred Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	5,000	5,000
PreferredStockRatePercentage	6.125%
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Depositary Shares Represented by One Preferred Share	100
Proceeds from issuance of preferred stock	$ 493,000,000
DividendRateReset	5 years
Preferred Stock Dividend Payment Rate Variable, Rate To Be Used in Future Periods	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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period			$ (119)
Net change in accumulated other comprehensive income (loss), net of tax	$ (29)	$ 9	212	$ 82
Accumulated other comprehensive income (loss), net of tax, balance at end of period	93		93
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	352	112	112	10
Net change in accumulated other comprehensive income (loss), net of tax	(32)	17	208	119
Accumulated other comprehensive income (loss), net of tax, balance at end of period	320	129	320	129
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	(16)	(8)	(17)	22
Net change in accumulated other comprehensive income (loss), net of tax	3	(8)	4	(38)
Accumulated other comprehensive income (loss), net of tax, balance at end of period	(13)	(16)	(13)	(16)
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	(214)	(187)	(214)	(188)
Net change in accumulated other comprehensive income (loss), net of tax	0	0	0	1
Accumulated other comprehensive income (loss), net of tax, balance at end of period	(214)	(187)	(214)	(187)
AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, balance at beginning of period	122	(83)	(119)	(156)
Net change in accumulated other comprehensive income (loss), net of tax	(29)	9	212	82
Accumulated other comprehensive income (loss), net of tax, balance at end of period	$ 93	$ (74)	$ 93	$ (74)

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Available-for-sale investment securities, net unrealized holding gains (losses) arising during the period, before tax	$ (42)	$ 24	$ 275	$ 158
Available-for-sale investment securities, net unrealized holding gains (losses) arising during the period, tax benefit (expense)	10	(7)	(67)	(39)
Available-for-sale investment securities, net unrealized holding gains (losses) arising during the period, net of tax	(32)	17	208	119
Available-for-sale investment securities, net change, before tax	(42)	24	275	158
Available-for-sale investment securities, net change, tax benefit (expense)	10	(7)	(67)	(39)
Available-for-sale investment securities, net change, net of tax	(32)	17	208	119
Cash flow hedges, net unrealized gains (losses) arising during the period, before tax	0	(9)	(7)	(44)
Cash flow hedges, net unrealized gains (losses) arising during the period, tax benefit (expense)	0	2	3	11
Cash flow hedges, net unrealized gains (losses) arising during the period, net of tax	0	(7)	(4)	(33)
Cash flow hedges, amounts reclassified from AOCI, before tax	4	(2)	11	(7)
Cash flow hedges, amounts reclassified from AOCI, tax benefit (expense)	(1)	1	(3)	2
Cash flow hedges, amounts reclassified from AOCI, net of tax	3	(1)	8	(5)
Cash flow hedges, net change, before tax	4	(11)	4	(51)
Cash flow hedges, net change, tax benefit (expense)	(1)	3	0	13
Cash flow hedges, net change, net of tax	$ 3	$ (8)	$ 4	(38)
Pension plan, unrealized gains (losses) arising during the period, before tax				1
Pension plan, unrealized gains (losses) arising during the period, tax benefit (expense)				0
Pension plan, unrealized gains (losses) arising during the period, net of tax				1
Pension plan, net change, before tax				1
Pension plan, net change, tax benefit (expense)				0
Pension plan, net change, net of tax				$ 1

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Increase (decrease) in income tax expense/benefit, amount	$ (36)	$ (584)

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income before income taxes	$ 959	$ 994	$ 420	$ 2,911
Income tax expense	$ 188	$ 224	$ 78	$ 662
Effective income tax rate (in percent)	19.60%	22.50%	18.60%	22.70%

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income	$ 771	$ 770	$ 342	$ 2,249
Preferred stock dividends	(15)	(15)	(31)	(31)
Net income available to common stockholders	756	755	311	2,218
Income allocated to participating securities	(5)	(6)	(2)	(15)
Net income allocated to common stockholders	$ 751	$ 749	$ 309	$ 2,203
Denominator:
Weighted-average shares of common stock outstanding	306	317	307	323
Weighted Average Number Diluted Shares Outstanding Adjustment	0	0	0	0
Weighted-average shares of common stock outstanding and common stock equivalents	306	317	307	323
Basic earnings per common share (in dollars per share)	$ 2.45	$ 2.36	$ 1	$ 6.83
Diluted earnings per common share (in dollars per share)	$ 2.45	$ 2.36	$ 1	$ 6.82

Capital Adequacy (Schedule of M

Capital Adequacy (Schedule of Minimum and Well-Capitalized Requirements) (Details) $ in Millions		Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)
Discover Bank [Member]
Compliance with Regulatory Capital Requirements [Line Items]
Total capital to risk-weighted assets, actual amount		$ 13,838	$ 13,441
Total capital to risk-weighted assets, actual ratio (in percent)	[1]	0.152	0.138
Total capital to risk-weighted assets, minimum capital requirements, amount		$ 7,304	$ 7,776
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]	$ 9,130	$ 9,720
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		$ 11,729	$ 11,203
Tier I capital to risk-weighted assets, actual ratio (in percent)	[1]	0.128	0.115
Tier I capital to risk-weighted assets, minimum capital requirements, amount		$ 5,478	$ 5,832
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]	$ 7,304	$ 7,776
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		$ 11,729	$ 11,203
Tier I capital to average assets, actual ratio (in percent)	[1]	0.102	0.101
Tier I capital to average assets, minimum capital requirements, amount		$ 4,614	$ 4,435
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]	$ 5,767	$ 5,544
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		$ 11,729	$ 11,203
CET1 capital to risk-weighted assets, actual ratio (in percent)	[1]	0.128	0.115
CET1 capital to risk-weighted assets, minimum capital requirements, amount		$ 4,109	$ 4,374
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]	$ 5,935	$ 6,318
CET1 capital to risk-weighted assets, capital requirements to be classified as well-capitalized, ratio (in percent)	[2]	6.50%	6.50%
Parent Company [Member]
Compliance with Regulatory Capital Requirements [Line Items]
Total capital to risk-weighted assets, actual amount		$ 14,046	$ 13,250
Total capital to risk-weighted assets, actual ratio (in percent)	[1]	0.152	0.135
Total capital to risk-weighted assets, minimum capital requirements, amount		$ 7,389	$ 7,860
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]	$ 9,236	$ 9,825
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		$ 12,325	$ 11,595
Tier I capital to risk-weighted assets, actual ratio (in percent)	[1]	0.133	0.118
Tier I capital to risk-weighted assets, minimum capital requirements, amount		$ 5,541	$ 5,895
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]	$ 5,541	$ 5,895
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		$ 12,325	$ 11,595
Tier I capital to average assets, actual ratio (in percent)	[1]	0.106	0.103
Tier I capital to average assets, minimum capital requirements, amount		$ 4,662	$ 4,482
Tier I capital to average assets, minimum capital requirements, ratio (in percent)		0.040	0.040
CET1 capital to risk-weighted assets, actual amount		$ 11,269	$ 11,032
CET1 capital to risk-weighted assets, actual ratio (in percent)	[1]	0.122	0.112
CET1 capital to risk-weighted assets, minimum capital requirements, amount		$ 4,156	$ 4,421
CET1 capital to risk-weighted assets, minimum capital requirements, ratio (in percent)		4.50%	4.50%
[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, 2020	Dec. 31, 2019
Commitments, Contingencies and Guarantees [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 50
Escrow deposits and settlement withholdings	19	$ 8
Commitments to Extend Credit [Member]
Commitments, Contingencies and Guarantees [Line Items]
Unused commitments to extend credit for loans	$ 215,000

Commitments, Contingencies an_4

Commitments, Contingencies and Guarantees (Schedule of Merchant Chargeback Guarantee) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Merchant Chargeback Guarantees [Member]
Loss Contingencies [Line Items]
Aggregate sales transaction volume	[1]	$ 46,128	$ 44,332	$ 125,214	$ 125,922
[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	Jul. 22, 2015	Sep. 30, 2020
Unfavorable Regulatory Action [Member] | Consumer Financial Protection Bureau Consent Order [Member]
Loss Contingencies [Line Items]
Amount of civil money penalty for consent order	$ 2.5
Maximum [Member] | Pending and Threatened Litigation [Member]
Loss Contingencies [Line Items]
Aggregate range of reasonably possible losses		$ 220
Minimum [Member] | Unfavorable Regulatory Action [Member] | Consumer Financial Protection Bureau Consent Order [Member]
Loss Contingencies [Line Items]
Aggregate range of reasonably possible losses	$ 16

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss	$ 0	$ 0
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		59,000,000
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	$ 309,000,000	$ 309,000,000
Available for sale securities, weighted average coupon rate (in percent)	2.81%	2.81%
Available for sale securities, weighted average remaining maturity (in years)		3 years
Securities Held as Collateral, at Fair Value	$ 10,700,000,000	$ 10,700,000,000

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, 2020		Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value	[1]	$ 20,573		$ 10,323
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]	9,548		9,906
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]	11,025	[2]	417
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		20,573		10,323
Fair Value, Recurring [Member] | Interest Rate Swaps [Member] | Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value	[3]	1		2
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 financial instruments, liabilities, fair value	[3]	1		4
Fair Value, Recurring [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value	[3]			1
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		9,548		9,906
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		11,025		417
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		9,548		9,906
Fair Value, Recurring [Member] | Level 1 [Member] | Interest Rate Swaps [Member] | Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value		0		0
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 financial instruments, liabilities, fair value		0		0
Fair Value, Recurring [Member] | Level 1 [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value				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		9,548		9,906
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 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, fair value		11,025		417
Fair Value, Recurring [Member] | Level 2 [Member] | Interest Rate Swaps [Member] | Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value	[3]	1		2
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 financial instruments, liabilities, fair value	[3]	1		4
Fair Value, Recurring [Member] | Level 2 [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value	[3]			1
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		0
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		11,025		417
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, Recurring [Member] | Level 3 [Member] | Interest Rate Swaps [Member] | Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value		0		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 financial instruments, liabilities, fair value		0		0
Fair Value, Recurring [Member] | Level 3 [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, liabilities, fair value				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		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
[1]	Available-for-sale investment securities are reported at fair value.
[2]	Maturities of residential mortgage-backed securities 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		9 Months Ended
		Sep. 30, 2020		Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	[1]	$ 290		$ 274
Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	[1],[2]	290	[3]	274
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		290		274
Net loan receivables		89,767		96,094
Cash and cash equivalents	[4]	9,513		6,924
Restricted cash	[4]	576		40
Accrued interest receivables	[4],[5]	1,008		1,044
Time deposits	[6]	31,739		34,910
Long-term borrowings		22,792		26,572
Accrued interest payables	[4],[5]	170		283
Estimated Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		11,514		14,383
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		11,278		12,189
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		290		274
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]	9,513		6,924
Restricted cash	[4]	576		40
Accrued interest receivables		0		0
Time deposits		0		0
Long-term borrowings		0		0
Accrued interest payables		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		290		274
Net loan receivables		0		0
Cash and cash equivalents		0		0
Restricted cash		0		0
Accrued interest receivables	[4],[5]	1,008		1,044
Time deposits	[6]	31,739		34,910
Long-term borrowings		22,656		26,400
Accrued interest payables	[4],[5]	170		283
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		11,378		14,211
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		11,278		12,189
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		290		274
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		89,767		96,094
Cash and cash equivalents		0		0
Restricted cash		0		0
Accrued interest receivables		0		0
Time deposits		0		0
Long-term borrowings		136		172
Accrued interest payables		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		136		172
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		281		272
Net loan receivables		80,434		92,511
Cash and cash equivalents	[4]	9,513		6,924
Restricted cash	[4]	576		40
Accrued interest receivables	[4],[5]	1,008		1,044
Time deposits	[6]	30,842		34,381
Long-term borrowings		21,841		25,701
Accrued interest payables	[4],[5]	170		283
Carrying Value [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		11,425		14,284
Carrying Value [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term borrowings		10,416		11,417
Carrying Value [Member] | Residential Mortgage-Backed Securities - Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities		281		$ 272
Fair Value, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset Impairment Charges		59
Other Short-term Investments Fair Value Disclosure	[4]	8,048
Short-term Debt, Fair Value		10,700
Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Short-term Investments Fair Value Disclosure	[4]	8,048
Short-term Debt, Fair Value		0
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Short-term Investments Fair Value Disclosure		0
Short-term Debt, Fair Value		10,700
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Short-term Investments Fair Value Disclosure		0
Short-term Debt, Fair Value		0
Fair Value, Nonrecurring [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Short-term Investments Fair Value Disclosure	[4]	8,048
Short-term Debt, Fair Value		$ 10,700
[1]	Held-to-maturity investment securities are reported at amortized cost.
[2]	Amounts represent residential mortgage-backed securities 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 residential mortgage-backed securities 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	9 Months Ended
	Sep. 30, 2020USD ($)
Derivative [Line Items]
Additional collateral	$ 9
Interest Expense [Member]
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months	$ 4
Deposits [Member]
Derivative [Line Items]
Initial maximum period for cash flow hedges (in years)	7 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, 2020USD ($)transactions		Sep. 30, 2020EUR (€)transactions	Sep. 30, 2020GBP (£)transactions	Sep. 30, 2020SGD ($)transactions	Sep. 30, 2020INR (₨)transactions	Dec. 31, 2019USD ($)transactions		Dec. 31, 2019EUR (€)transactions	Dec. 31, 2019GBP (£)transactions	Dec. 31, 2019SGD ($)transactions	Dec. 31, 2019INR (₨)transactions
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	$ 0						$ 0
Collateral held, derivative assets	[2]	0						0
Total net derivative assets		0						0
Derivative liabilities	[1]	2						7
Collateral posted, derivative liabilities	[2]	(2)						(7)
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		$ 300						900
Derivative, number of outstanding derivative contracts (in transactions) | transactions		1		1	1	1	1
Derivative assets		$ 0						0
Derivative liabilities		1						2
Designated as Hedges [Member] | Fair Value Hedging [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 12,175						14,275
Derivative, number of outstanding derivative contracts (in transactions) | transactions		16		16	16	16	16
Derivative assets		$ 0						0
Derivative liabilities		1						4
Not Designated as Hedges [Member] | Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 23	[3]	€ 6	£ 6	$ 1	₨ 596	38	[3]	€ 9	£ 14	$ 1	₨ 596
Derivative, number of outstanding derivative contracts (in transactions) | transactions		6		6	6	6	6
Derivative assets		$ 0						0
Derivative liabilities		$ 0						1
Not Designated as Hedges [Member] | When-Issued Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount								$ 42
Derivative, number of outstanding derivative contracts (in transactions) | transactions		0		0	0	0	0	2		2	2	2	2
[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, 2020, the Company had no outstanding contracts. At December 31, 2019, the Company had two outstanding contracts with a total notional amount of $42 million and immaterial fair value.
[2]	Collateral amounts, which consist of both 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 596 million as of September 30, 2020, and notional amounts of EUR 9 million, GBP 14 million, SGD 1 million and INR 596 million as of December 31, 2019.

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, 2020	Dec. 31, 2019
Schedule of Hedged Items in Fair Value Hedging Relationship [Line Items]
Carrying amount of hedged assets/liabilities	$ 12,481	$ 14,244
Cumulative amount of fair value hedging adjustment increasing (decreasing) the carrying amount of hedged assets/liabilities	$ 339	$ 13

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amounts reclassified from OCI into earnings, cash flow hedges	$ (4)	$ 2	$ (11)	$ 7
Interest Expense [Member] | Deposits [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded	(287)	(407)	(1,000)	(1,194)
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	(4)	1	(9)	3
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] | Long-term Borrowings [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded	(126)	(231)	(479)	(721)
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	1	(2)	4
Gains (losses) on hedged items, fair value hedges	59	(20)	(326)	(160)
Gains (losses) on interest rate swaps, fair value hedges	(9)	12	434	128
Total gains (losses) on fair value hedges	50	(8)	108	(32)
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts of income and expense line items presented in the statements of income in which the effects of fair value or cash flow hedges are recorded	17	23	59	73
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

Segment Disclosures (Narrative)

Segment Disclosures (Narrative) (Details)	9 Months Ended
	Sep. 30, 2020segment
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, 2020		Sep. 30, 2019		Sep. 30, 2020		Sep. 30, 2019
Segment Reporting Information [Line Items]
Interest income	$ 2,681		$ 3,040		$ 8,335		$ 8,954
Interest expense	416		638		1,482		1,915
Net interest income	2,265		2,402		6,853		7,039
Provision for credit losses	750	[1]	799	[2]	4,603	[3]	2,395	[2]
Other income	449		498		1,411		1,476
Other expense	1,005		1,107		3,241		3,209
Income before income taxes	959		994		420		2,911
Other [Member]
Segment Reporting Information [Line Items]
Interest income	91		122		284		392
Credit Card Loans [Member]
Segment Reporting Information [Line Items]
Interest income	2,171		2,465		6,760		7,223
Total Other Loans [Member] | Private Student Loans [Member]
Segment Reporting Information [Line Items]
Interest income	182		204		569		612
Total Other Loans [Member] | Personal Loans [Member]
Segment Reporting Information [Line Items]
Interest income	237		249		722		727
Operating Segments [Member] | Direct Banking [Member]
Segment Reporting Information [Line Items]
Interest income	2,681		3,040		8,335		8,953
Interest expense	416		638		1,482		1,915
Net interest income	2,265		2,402		6,853		7,038
Provision for credit losses	750		799	[2]	4,603		2,395	[2]
Other income	371		409		1,091		1,217
Other expense	969		1,069		3,069		3,097
Income before income taxes	917		943		272		2,763
Operating Segments [Member] | Direct Banking [Member] | Other [Member]
Segment Reporting Information [Line Items]
Interest income	91		122		284		391
Operating Segments [Member] | Direct Banking [Member] | Credit Card Loans [Member]
Segment Reporting Information [Line Items]
Interest income	2,171		2,465		6,760		7,223
Operating Segments [Member] | Direct Banking [Member] | Total Other Loans [Member] | Private Student Loans [Member]
Segment Reporting Information [Line Items]
Interest income	182		204		569		612
Operating Segments [Member] | Direct Banking [Member] | Total Other Loans [Member] | Personal Loans [Member]
Segment Reporting Information [Line Items]
Interest income	237		249		722		727
Operating Segments [Member] | Payment Services [Member]
Segment Reporting Information [Line Items]
Interest income	0		0		0		1
Interest expense	0		0		0		0
Net interest income	0		0		0		1
Provision for credit losses	0		0	[2]	0		0	[2]
Other income	78		89		320		259
Other expense	36		38		172		112
Income before income taxes	42		51		148		148
Operating Segments [Member] | Payment Services [Member] | Other [Member]
Segment Reporting Information [Line Items]
Interest income	0		0		0		1
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
[1]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[2]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.
[3]	Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net		$ 238	$ 255	$ 691	$ 785
Protection products revenue		44	48	135	146
Transaction processing revenue		50	52	143	146
Other income subject to ASC 606		17	23	59	73
Loan fee income		100	120	304	326
Gains on equity investments		0	0	79	0
Total other income not subject to ASC 606		100	120	383	326
Total other income by operating segment		449	498	1,411	1,476
Customer rewards included in discount and interchange revenue		514	520	1,400	1,400
Deposit product fees reported in net interest income and excluded from other income subject to ASC 606		1		2	2
Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	238	255	691	785
Protection products revenue		44	48	135	146
Transaction processing revenue		50	52	143	146
Other income subject to ASC 606		17	23	59	73
Total other income subject to ASC 606	[2]	349	378	1,028	1,150
Operating Segments [Member] | Direct Banking [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		100	120	304	326
Gains on equity investments				0
Total other income not subject to ASC 606		100	120	304	326
Total other income by operating segment		371	409	1,091	1,217
Operating Segments [Member] | Direct Banking [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	225	238	644	738
Protection products revenue		44	48	135	146
Transaction processing revenue		0	0	0	0
Other income subject to ASC 606		2	3	8	7
Total other income subject to ASC 606	[2]	271	289	787	891
Operating Segments [Member] | Payment Services [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		0	0	0	0
Gains on equity investments				79
Total other income not subject to ASC 606		0	0	79	0
Total other income by operating segment		78	89	320	259
Operating Segments [Member] | Payment Services [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	13	17	47	47
Protection products revenue		0	0	0	0
Transaction processing revenue		50	52	143	146
Other income subject to ASC 606		15	20	51	66
Total other income subject to ASC 606	[2]	$ 78	$ 89	$ 241	$ 259
[1]	Net of rewards, including Cashback Bonus rewards, of $514 million and $520 million for the three months ended September 30, 2020 and 2019, respectively.
[2]	Excludes $1 million of deposit product fees that are reported within net interest income for the three months ended September 30, 2020. Deposit product fees were immaterial for the three months ended September 30, 2019.