Michael Stone, long-time president and chief operating officer of RLI Corp., is retiring at the end of 2015, capping a 20-year stint at the Illinois-based specialty insurer.

RLI said that Stone will continue to serve on the RLI board after he leaves his two executive positions on Dec. 31.

There is already a chosen successor. Craig Kliethermes, executive vice president of operations, becomes RLI’s next president and COO effective Jan. 1, 2016.

Stone is retiring after having served as RLI president and COO since 2002. But he’s been with RLI far longer, having first joined the company in 1996. He started as vice president, claim before becoming executive vice president in 1998.

RLI Chairman and CEO Jonathan Michael credited Stone with having helped RLI grow in a number of ways.

Stone, Michael said in prepared remarks, “has been an integral partner in RLI’s growth and success, providing outstanding leadership for our insurance operations.”

Kliethermes is also an RLI veteran. He also signed on with RLI in 2006, joining the company to take on the position of vice president, actuarial services. He was promoted to senior vice president, risk services in 2009, and has been in his current executive role since 2013.

Before RLI, Kliethermes gained experience in various executive roles at Lockton Companies, GE Insurance/Employers Reinsurance, and John Deere Insurance Company.

RLI focuses on niche property, casualty and surety markets.

Source: RLI Corp.