| Cover | Jan. 11, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 11, 2021 |
| Entity File Number | 001-35385 |
| Entity Registrant Name | Sterling Bancorp |
| Entity Central Index Key | 0001070154 |
| Entity Tax Identification Number | 80-0091851 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | Two Blue Hill Plaza |
| Entity Address, Address Line Two | Second Floor |
| Entity Address, City or Town | Pearl River |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10965 |
| City Area Code | 845 |
| Local Phone Number | 369-8040 |
| 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 Information [Line Items] | |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | STL |
| Security Exchange Name | NYSE |
| Series A Preferred Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Depositary Shares, each representing 1/40th interest in a share of 6.50% Non-cumulative Perpetual Preferred Stock, Series A |
| Trading Symbol | STLPRA |
| Security Exchange Name | NYSE |
