Document and Entity Information
| Document and Entity Information | Jan. 29, 2020 |
| Document And Entity Information [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 29, 2020 |
| Entity Registrant Name | PROSPERITY BANCSHARES INC |
| Entity Central Index Key | 0001068851 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-35388 |
| Entity Incorporation State Country Code | TX |
| Entity Tax Identification Number | 74-2331986 |
| Entity Address Address Line1 | 4295 San Felipe |
| Entity Address City Or Town | Houston |
| Entity Address State Or Province | TX |
| Entity Address Postal Zip Code | 77027 |
| City Area Code | 281 |
| Local Phone Number | 269-7199 |
| 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 $1.00 per share |
| Trading Symbol | PB |
| Security Exchange Name | NYSE |