| Cover | Feb. 26, 2020 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 26, 2020 |
| Entity File Number | 001-34280 |
| Entity Registrant Name | AMERICAN NATIONAL INSURANCE CO /TX/ |
| Entity Central Index Key | 0000904163 |
| Entity Tax Identification Number | 74-0484030 |
| Entity Incorporation, State or Country Code | TX |
| Entity Address, Address Line One | One Moody Plaza |
| Entity Address, City or Town | Galveston |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77550-7999 |
| City Area Code | 409 |
| Local Phone Number | 763-4661 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $1.00 |
| Trading Symbol | ANAT |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
