The index.mapping.ignore_malformed global setting can be set on the index level to allow to ignore malformed content globally across all mapping types (malformed content example is trying to index a text string value as a numeric type).
The index.mapping.ignore_malformed global setting can be set on the index level to allow to ignore malformed content globally across all mapping types (malformed content example is trying to index a text string value as a numeric type). for 1.3.7 version index
Based on the Tip here: https://www.elastic.co/guide/en/elasticsearch/reference/current/ignore-malformed.html
... it looks like you can set it for already mapped fields, in the current (2.1.x) release.