Document and Entity Information Document
Jul. 22, 2020
Cover [Abstract]  
Document Type 8-K
Document Period End Date Oct. 21, 2020
Entity Registrant Name DISCOVER FINANCIAL SERVICES
Entity File Number 001-33378
Entity Incorporation, State or Country Code 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
City Area Code 224
Local Phone Number 405-0900
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock, par value $0.01 per share
Trading Symbol DFS
Security Exchange Name NYSE
Entity Emerging Growth Company false
Entity Central Index Key 0001393612
Amendment Flag false