The Detroit Free Press said it confirmed the move with Martz, who was head coach of the St. Louis Rams for six seasons before joining the Lions in 2006.
Detroit suffered a second-half-of-the-season slump that included a six-game losing streak. Three times in that span Detroit failed to score more than 14 points.
Martz was the offensive coordinator at St. Louis in 1999 when the Rams piled up 526 points -- fifth-most in NFL history -- in the regular season and won the Super Bowl. He was selected the team's head coach in 2000 and took the Rams to the Super Bowl the following season.
He stepped back from coaching in 2005 when he was diagnosed with a heart ailment but he had subsequent run-ins with the Rams' front office and was fired after that season.