Mr. Nikkel joined the company as its president, chief operating officer, and a director in 1983. He was elected its chief executive officer in July 2001 and chairman of the board in August 2003.
Mr. Nikkel retired as an employee and as the chief executive officer of the company on April 1, 2005, but retained his position as chairman of the board.
J. Michael Adcock, a current board member, has been elected the new chairman.
Mr. Adcock has served on the company's board since 1997. He is a member of the Audit and Nominating and Governance Committees, as well as chairman of the Compensation Committee.
Mr. Adcock has many years of experience in banking, investments, and energy operations, as well as executive leadership experience as chief executive officer of two companies, one of which was a publicly-traded international energy company.