| Document and Entity Information | Mar. 12, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000933136 |
| Document Type | 8-K |
| Document Period End Date | Mar. 12, 2021 |
| Entity Registrant Name | Mr. Cooper Group Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-14667 |
| Entity Tax Identification Number | 91-1653725 |
| Entity Address, Address Line One | 8950 Cypress Waters Blvd. |
| Entity Address, City or Town | Coppell |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75019 |
| City Area Code | 469 |
| Local Phone Number | 549-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value per share |
| Trading Symbol | COOP |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
