CONDENSED CONSOLIDATED BALANCE SHEETS - UNAUDITED (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Trade accounts receivable-billed, allowance	$ 3,718	$ 3,628
Property and equipment, accumulated depreciation	110,797	105,073
Intangibles, accumulated amortization	251,508	245,614
Customer costs, accumulated amortization	42,802	39,893
Current portion of long-term debt, unamortized discounts	3,119	0
Long-term debt, unamortized discounts	$ 1,017	$ 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 outstanding	32,963,000	32,713,000
Treasury stock, shares	36,122,000	35,980,000
Software
Intangibles, accumulated amortization	$ 143,662	$ 139,836
Acquired customer contracts
Intangibles, accumulated amortization	$ 107,846	$ 105,778