CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts receivable, allowance for doubtful accounts	$ 3,295	$ 3,995
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, authorized	800	800
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, authorized	1,500,000	1,500,000
Common stock, issued	144,361	141,671
Common stock, outstanding	87,936	92,372
Treasury stock, shares	56,425	49,299
Common Class B
Common stock, par value	$ 0.001	$ 0.001
Common stock, authorized	39,000	39,000
Common stock, issued	0	0
Common stock, outstanding	0	0