Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Trade accounts receivable-billed, allowance	$ 2,918	$ 2,421
Property and equipment, accumulated depreciation	120,159	116,125
Software, accumulated amortization	65,959	56,521
Client contracts, accumulated amortization	178,338	159,225
Long-term debt, unamortized original issue discount	$ 26,576	$ 30,256
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000	100,000
Common stock, shares outstanding	33,711	33,822
Treasury stock, shares	31,530	30,707