| Cover - shares | 3 Months Ended | |
| Mar. 31, 2021 | May 05, 2021 | |
| Document Type | 10-Q/A | |
| Document Quarterly Report | true | |
| Document Period End Date | Mar. 31, 2021 | |
| Document Transition Report | false | |
| Entity File Number | 001-38908 | |
| Entity Registrant Name | DRAFTKINGS INC. | |
| Entity Incorporation, State or Country Code | NV | |
| Entity Tax Identification Number | 84-4052441 | |
| Entity Address, Address Line One | 222 Berkeley Street | |
| Entity Address, Address Line Two | 5th Floor | |
| Entity Address, City or Town | Boston | |
| Entity Address, State or Province | MA | |
| Entity Address, Postal Zip Code | 02116 | |
| City Area Code | 617 | |
| Local Phone Number | 986-6744 | |
| Title of 12(b) Security | Class A Common Stock, $0.0001 par value | |
| Trading Symbol | DKNG | |
| Security Exchange Name | NASDAQ | |
| Entity Current Reporting Status | Yes | |
| Entity Interactive Data Current | Yes | |
| Entity Filer Category | Large Accelerated Filer | |
| Entity Small Business | false | |
| Entity Emerging Growth Company | false | |
| Entity Shell Company | false | |
| Current Fiscal Year End Date | --12-31 | |
| Document Fiscal Year Focus | 2021 | |
| Document Fiscal Period Focus | Q1 | |
| Entity Central Index Key | 0001772757 | |
| Amendment Flag | false | |
| Class A Common Stock | ||
| Entity Common Stock, Shares Outstanding | 400,980,887 | |
| Class B Common Stock | ||
| Entity Common Stock, Shares Outstanding | 393,013,951 |
