What does 2 Chronicles 12:15 mean?

Everything else about Rehoboam, from start to finish, is written in the records of Shemaiah the prophet and Iddo the seer. Rehoboam and Jeroboam were always at odds with each other. 2 Chronicles 12:15 - Modern Text Bible

(There's more to Rehoboam's story in other records, and his reign was marked by constant conflict with Jeroboam.)