CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Trade accounts receivable-billed, allowance	$ 3,080	$ 3,600
Property and equipment, accumulated depreciation	122,866	112,282
Current portion of long-term debt, unamortized discounts	296	8,632
Long-term debt, unamortized discounts	$ 23,007	$ 4,738
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 reserved for employee stock purchase plan and stock incentive plans	3,971,000	4,664,000
Common stock, shares outstanding	32,261,000	32,555,000
Common stock warrants, issued	2,851,000	2,851,000
Common stock warrants, outstanding	2,851,000	2,851,000
Treasury stock, shares	34,919,000	34,601,000
Software
Accumulated amortization	$ 99,316	$ 95,094
Client contracts
Accumulated amortization	$ 96,723	$ 87,890