| Cover Page Cover Page | Jun. 14, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 14, 2021 |
| Entity Registrant Name | LGI HOMES, INC. |
| Entity Central Index Key | 0001580670 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36126 |
| Entity Tax Identification Number | 46-3088013 |
| Entity Address, Address Line One | 1450 Lake Robbins Drive, |
| Entity Address, Address Line Two | Suite 430, |
| Entity Address, City or Town | The Woodlands, |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77380 |
| City Area Code | 281 |
| Local Phone Number | 362-8998 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | LGIH |
| Security Exchange Name | NASDAQ |
