Allen Park — The Detroit Lions are set to add another significant piece via free agency, agreeing to terms with linebacker Jamie Collins on Monday evening.

Collins' agent confirmed the transaction via Twitter. According to the NFL Network, it's a three-year, $30 million deal with $18 million guaranteed. Collins was Detroit's second free-agent agreement on Monday, following offensive lineman Halapoulivaati Vaitai.

The moves can't be completed until Wednesday afternoon, when players are permitted to sign with new organizations, but it will reunite Collins with Lions coach Matt Patricia, who served as the linebacker's defensive coordinator in New England from 2013-16. 

A second-round draft pick out of Southern Miss in 2013, Collins quickly developed into a key piece in New England's defense, earning All-Pro and Pro Bowl honors in 2015. 

More: Lions reach agreement on two-year deal with defensive tackle Nick Williams

Near the end of his rookie contract, the Patriots shipped Collins to the Cleveland Browns in the middle of the 2016 season. He re-signed with the Browns in 2017 — a four-year, $50 million pact — but was released two years later. 

Collins, 30, returned to New England last season and re-established himself as one of the game's more versatile playmaking linebackers. In 16 games (15 starts), he recorded 85 tackles, seven sacks, three interceptions and four forced fumbles. 

An outside linebacker, with experience playing inside, Collins is comfortable lining up both on the line of scrimmage and off the ball. It will be interesting to see how the Lions incorporate him into the team's crowded depth chart.

The team returns its entire corps from a season ago, including starters Devon Kennard, Jarrad Davis and Christian Jones, as well as 2019 second-round draft pick Jahlani Tavai.