CONDENSED CONSOLIDATED BALANCE SHEETS - UNAUDITED (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Trade accounts receivable-billed, allowance	$ 3,961	$ 4,149
Property and equipment, accumulated depreciation	108,542	123,126
Accumulated amortization	193,408
Client contract costs, accumulated amortization	30,932	0
Long-term debt, unamortized discounts	$ 16,721	$ 18,264
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	33,561,000	33,516,000
Common stock warrants, vested	439,000	439,000
Common stock warrants, issued	1,425,000	1,425,000
Treasury stock, shares	34,334,000	34,075,000
Software
Accumulated amortization	$ 114,010	$ 108,986
Client contracts
Accumulated amortization	0	97,109
Acquired client contracts
Accumulated amortization	$ 79,398	$ 0