CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Other property and equipment, accumulated depreciation	$ 27,424	$ 24,091
Other assets, accumulated depreciation and amortization	$ 4,376	$ 3,560
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	55,302,325	54,884,542
Treasury stock, shares (in shares)	16,582	16,582