Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Consolidated Balance Sheets [Abstract]
Accounts and notes receivable, allowance	$ 2,401	$ 2,079
Accumulated depreciation	$ 376,050	$ 360,722
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	52,524,969	52,129,395
Common stock, shares outstanding	45,220,304	44,953,620
Treasury stock, shares	7,304,665	7,175,775