Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Trade accounts receivable-billed, allowance	$ 2,925	$ 2,421
Property and equipment, accumulated depreciation	120,117	116,125
Software, accumulated amortization	59,565	56,521
Client contracts, accumulated amortization	166,174	159,225
Long-term debt, unamortized original issue discount	$ 29,053	$ 30,256
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares outstanding	34,127,496	33,822,232
Treasury stock, shares	31,034,308	30,551,519