| Cover Page | Mar. 12, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 12, 2021 |
| Entity Central Index Key | 0000019612 |
| Amendment Flag | false |
| Entity Registrant Name | TCF FINANCIAL CORPORATION |
| Entity Incorporation, State or Country Code | MI |
| Entity File Number | 001-39009 |
| Entity Tax Identification Number | 38-2022454 |
| Entity Address, Address Line One | 333 W. Fort Street |
| Entity Address, Address Line Two | Suite 1800 |
| Entity Address, City or Town | Detroit |
| Entity Address, State or Province | MI |
| Entity Address, Postal Zip Code | 48226 |
| City Area Code | 800 |
| Local Phone Number | 867-9757 |
| Written Communications | true |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock (par value $1 per share) |
| Trading Symbol | TCF |
| Security Exchange Name | NASDAQ |
| Depositary Shares [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Depositary Shares |
| Trading Symbol | TCFCP |
| Security Exchange Name | NASDAQ |
