| Document and Entity Information | Nov. 04, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 4, 2021 |
| Entity File Number | 001-37931 |
| Entity Registrant Name | GTY TECHNOLOGY HOLDINGS INC. |
| Entity Incorporation, State or Country Code | MA |
| Entity Tax Identification Number | 83-2860149 |
| Entity Address, Address Line One | 800 Boylston Street |
| Entity Address, Adress Line Two | 16th Floor |
| Entity Address, State or Province | MA |
| Entity Address, City or Town | Boston |
| Entity Address, Postal Zip Code | 02199 |
| City Area Code | 877 |
| Local Phone Number | 465-3200 |
| 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 $0.0001 per share |
| Trading Symbol | GTYH |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001682325 |
| Amendment Flag | false |
