| Document and Entity Information | Feb. 20, 2020 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000904163 |
| Document Type | 8-K |
| Document Period End Date | Feb. 20, 2020 |
| Entity Registrant Name | AMERICAN NATIONAL INSURANCE CO |
| Entity Incorporation State Country Code | TX |
| Entity File Number | 001-34280 |
| Entity Tax Identification Number | 74-0484030 |
| 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 | true |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, Par Value $1.00 |
| Trading Symbol | ANAT |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
