Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Consolidated Balance Sheets [Abstract]
Allowances	$ 16,918	$ 13,315
Preferred shares, par value	$ 0.001	$ 0.001
Preferred shares, authorized	5,000,000	5,000,000
Preferred shares, outstanding	0	0
Common shares, par value	$ 0.001	$ 0.001
Common shares, authorized	250,000,000	250,000,000
Common shares, issued	91,565,533	91,047,297
Common shares, outstanding	88,345,143	88,662,845
Treasury stock, shares	3,220,390	2,384,452