CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 7,299	$ 7,858
Preferred shares, authorized	5,000,000	5,000,000
Preferred shares, issued	0	0
Preferred shares, outstanding	0	0
Common shares, authorized	240,000,000	240,000,000
Common shares, issued	98,151,434	98,581,434
Common shares, outstanding	70,693,389	76,997,161
Treasury shares	27,888,045	21,584,273