| Cover | Nov. 02, 2020 |
| Schedule of Capitalization, Equity [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 2, 2020 |
| Entity File Number | 001-38296 |
| Entity Registrant Name | LEGACY ACQUISITION CORP. |
| Entity Central Index Key | 0001698113 |
| Entity Tax Identification Number | 81-3674868 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1308 Race Street |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | Cincinnati |
| Entity Address, State or Province | OH |
| Entity Address, Postal Zip Code | 45202 |
| City Area Code | (513) |
| Local Phone Number | 618-7161 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
| Units, each consisting of one share of Class A common stock and one Warrant to purchase one-half of one share of Class A common stock | |
| Schedule of Capitalization, Equity [Line Items] | |
| Title of 12(b) Security | Units, each consisting of one share of Class A common stock and one Warrant to purchase one-half of one share of Class A common stock |
| Trading Symbol | LGC.U |
| Security Exchange Name | NYSE |
| Class A common stock, par value $0.0001 per share | |
| Schedule of Capitalization, Equity [Line Items] | |
| Title of 12(b) Security | Class A common stock, par value $0.0001 per share |
| Trading Symbol | LGC |
| Security Exchange Name | NYSE |
| Warrants, exercisable for one-half of one share of Class A common stock for $5.75 per half share, or $11.50 per whole share | |
| Schedule of Capitalization, Equity [Line Items] | |
| Title of 12(b) Security | Warrants, exercisable for one-half of one share of Class A common stock for $5.75 per half share, or $11.50 per whole share |
| Trading Symbol | LGC.WS |
| Security Exchange Name | NYSE |
