| Document and Entity Information | Oct. 22, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 22, 2020 |
| Entity Registrant Name | HERITAGE COMMERCE CORP |
| Entity Central Index Key | 0001053352 |
| Entity File Number | 000-23877 |
| Entity Tax Identification Number | 77-0469558 |
| Entity Incorporation, State or Country Code | CA |
| Entity Address, Address Line One | 224 Airport Parkway |
| Entity Address, City or Town | San Jose |
| Entity Address, Postal Zip Code | 95110 |
| Entity Address, State or Province | CA |
| City Area Code | 408 |
| Local Phone Number | 947-6900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, No Par Value |
| Trading Symbol | HTBK |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
