v3.26.1
Document and Entity Information
May 21, 2026
Document And Entity Information [Line Items]  
Entity Registrant Name FISERV INC
Amendment Flag false
Entity Central Index Key 0000798354
Document Type 8-K
Document Period End Date May 21, 2026
Entity Incorporation State Country Code WI
Entity File Number 1-38962
Entity Tax Identification Number 39-1506125
Entity Address, Address Line One 600 N. Vel R. Phillips Avenue
Entity Address, City or Town Milwaukee
Entity Address, State or Province WI
Entity Address, Postal Zip Code 53203
City Area Code (262)
Local Phone Number 879-5000
Written Communications false
Soliciting Material false
Pre Commencement Tender Offer false
Pre Commencement Issuer Tender Offer false
Entity Emerging Growth Company false
Common Stock [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Common Stock, par value $0.01 per share
Trading Symbol FISV
Security Exchange Name NASDAQ
A 1.125 Senior Notes Due July 2027 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 1.125% Senior Notes due 2027
Trading Symbol FISV27
Security Exchange Name NASDAQ
A 1.625 Senior Notes Due 2030 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 1.625% Senior Notes due 2030
Trading Symbol FISV30
Security Exchange Name NASDAQ
A 3.000 Senior Notes Due 2031 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 3.000% Senior Notes due 2031
Trading Symbol FISV31
Security Exchange Name NASDAQ
A 4.500 Senior Notes Due 2031 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 4.500% Senior Notes due 2031
Trading Symbol FISV31A
Security Exchange Name NASDAQ
A 2.875 Senior Notes Due 2028 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 2.875% Senior Notes due 2028
Trading Symbol FISV28C
Security Exchange Name NASDAQ
A 3.500 Senior Notes Due 2032 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 3.500% Senior Notes due 2032
Trading Symbol FISV32
Security Exchange Name NASDAQ
A 4.000 Senior Notes Due 2036 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 4.000% Senior Notes due 2036
Trading Symbol FISV36
Security Exchange Name NASDAQ