CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Trade accounts receivable-billed, allowance	$ 4,250	$ 3,628
Property and equipment, accumulated depreciation	111,244	105,073
Customer contract costs, accumulated amortization	32,410	39,893
Long-term debt, unamortized discounts	$ 3,406	$ 5,346
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	4,704,000	5,929,000
Common stock, shares outstanding	32,495,000	32,713,000
Treasury stock, shares	36,713,000	35,980,000
Software
Intangibles, accumulated amortization	$ 152,283	$ 139,836
Acquired customer contracts
Intangibles, accumulated amortization	$ 114,166	$ 105,778