(CBS) The Bears signed running back Michael Bush to a four-year contract Thursday.

The Chicago Tribune reports the deal is worth $14 million, with $7 million guaranteed.

Bush will provide depth in the Bears backfield behind Matt Forte and give the Bears some insurance with the franchise tag currently placed on their starting running back. The move also likely points to the exit of Marion Barber.

Bush spent the last four years with the Oakland Raiders after being drafted by the team in the fourth round of the 2007 NFL Draft. He has 2,642 yards and 21 touchdowns in his career, but enjoyed his most productive season last year as he set career highs in attempts (256), yards (977), touchdowns (7), receptions (37), receiving yards (418) and starts (9) while playing in all 16 games.