CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Billed receivables, allowances	$ 7,982	$ 4,843
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.005	$ 0.005
Common stock, shares authorized	70,000,000	70,000,000
Common stock, shares issued	46,606,796	40,821,516
Treasury stock, shares	6,834,010	7,178,427