Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounts receivable, allowance for doubtful accounts	$ 2,407	$ 3,090
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	100,000,000	100,000,000
Shares, issued	41,571,338	41,497,733
Shares, outstanding	41,571,338	41,497,733
Restricted Stock [Member]
Shares, issued	243,440	244,317
Shares, outstanding	243,440	244,317