Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts and notes receivable, allowance for doubtful accounts	$ 1,931	$ 2,079
Accumulated depreciation	$ 397,972	$ 360,722
Ordinary shares, shares outstanding	45,326,430	44,953,620
Treasury shares, shares		7,175,775
Common Class A
Ordinary shares, nominal value		$ 0.0001
Ordinary shares, shares authorized		125,000,000
Ordinary shares, shares issued		52,129,395
Ordinary shares, shares outstanding		44,953,620
Ordinary Shares
Ordinary shares, nominal value	$ 0.01
Ordinary shares, shares issued	45,326,430
Ordinary shares, shares outstanding	45,326,430