CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 6,103	$ 6,353
Common stock, par value (in dollars per share)	$ 0.008	$ 0.008
Common stock, authorized shares	1,000,000,000	1,000,000,000
Common stock, shares issued	57,578,431	56,567,236
Treasury stock, shares	7,779,645	7,421,128