| Document and Entity Information | Oct. 29, 2020 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 29, 2020 |
| Entity File Number | 001-35000 |
| Entity Registrant Name | Walker & Dunlop, Inc. |
| Entity Incorporation, State or Country Code | MD |
| Entity Tax Identification Number | 80-0629925 |
| Entity Address, Address Line One | 7501 Wisconsin Avenue |
| Entity Address, Adress Line Two | Suite 1200E |
| Entity Address, State or Province | MD |
| Entity Address, City or Town | Bethesda |
| Entity Address, Postal Zip Code | 20814 |
| City Area Code | 301 |
| Local Phone Number | 215-5500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 Par Value Per Share |
| Trading Symbol | WD |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001497770 |
| Amendment Flag | false |
