CONDENSED CONSOLIDATED BALANCE SHEETS - UNAUDITED (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Trade accounts receivable-billed, allowance	$ 3,937	$ 3,323
Property and equipment, accumulated depreciation	144,486	138,065
Accumulated amortization	174,971	175,382
Current maturities of long-term debt, unamortized original issue discount	11,106	0
Long-term debt, unamortized original issue discount	$ 0	$ 14,169
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 warrants, outstanding	32,760,000	33,945,000
Common stock warrants, issued	2,851,000	2,851,000
Treasury stock, shares	34,356,000	32,763,000
Software
Accumulated amortization	$ 92,324	$ 86,797
Client contracts
Accumulated amortization	$ 82,647	$ 88,585
Common stock warrant
Common stock warrants, outstanding	2,851,000	2,851,000