CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Trade accounts receivable-billed, allowance		$ 5,528	$ 4,250
Property and equipment, accumulated depreciation		105,466	111,244
Customer contract costs, accumulated amortization		30,601	32,410
Long-term debt, unamortized discounts		$ 2,656	$ 3,406
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		5,091,000	4,704,000
Common stock, shares outstanding		31,269,000	32,495,000
Treasury stock, shares		38,210,000	36,713,000
Software
Intangibles, accumulated amortization		$ 150,337	$ 152,283
Acquired customer contracts
Intangibles, accumulated amortization	[1]	$ 120,080	$ 114,166

[1] Acquired customer contracts represent assets acquired in our prior business acquisitions. Acquired customer contracts are amortized over their estimated useful lives ranging from one to twenty years based on the approximate pattern in which the economic benefits of the intangible assets are expected to be realized, with the amortization expense included as cost of revenue in our Income Statements.