CONDENSED CONSOLIDATED BALANCE SHEETS - UNAUDITED - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 163,768	$ 188,699
Short-term investments	48,325	51,598
Total cash, cash equivalents and short-term investments	212,093	240,297
Settlement and merchant reserve assets	142,684	166,031
Trade accounts receivable:
Billed, net of allowance of $3,546 and $3,628	223,228	226,623
Unbilled	43,583	37,785
Income taxes receivable	8,170	2,167
Other current assets	48,186	41,688
Total current assets	677,944	714,591
Non-current assets:
Property and equipment, net of depreciation of $117,113 and $105,073	81,261	81,759
Operating lease right-of-use assets	100,881	110,756
Intangible assets	76,813	74,465
Goodwill	274,843	272,322
Customer contract costs, net of amortization of $46,370 and $39,893	46,799	47,238
Deferred income taxes	9,500	10,205
Other assets	23,643	20,664
Total non-current assets	613,740	617,409
Total assets	1,291,684	1,332,000
Current liabilities:
Current portion of long-term debt, net of unamortized discounts of $2,032 and zero	242,968	14,063
Operating lease liabilities	23,303	22,651
Customer deposits	32,418	39,992
Trade accounts payable	31,852	29,834
Accrued employee compensation	76,851	86,289
Settlement and merchant reserve liabilities	141,130	165,064
Deferred revenue	54,956	52,357
Income taxes payable	937	6,627
Other current liabilities	18,824	19,383
Total current liabilities	623,239	436,260
Non-current liabilities:
Long-term debt, net of unamortized discounts of $880 and $5,346	104,120	337,154
Operating lease liabilities	85,599	95,926
Deferred revenue	14,288	17,275
Income taxes payable	2,508	2,436
Deferred income taxes	10,941	5,109
Other non-current liabilities	11,209	15,445
Total non-current liabilities	228,665	473,345
Total liabilities	851,904	909,605
Stockholders' equity:
Preferred stock, par value $.01 per share; 10,000 shares authorized; zero shares issued and outstanding
Common stock, par value $.01 per share; 100,000 shares authorized; 32,797 and 32,713 shares outstanding	704	700
Additional paid-in capital	477,010	470,557
Treasury stock, at cost; 36,275 and 35,980 shares	(907,601)	(894,126)
Accumulated other comprehensive income (loss):
Unrealized gains on short-term investments, net of tax		13
Cumulative foreign currency translation adjustments	(29,294)	(31,151)
Accumulated earnings	898,961	876,402
Total stockholders' equity	439,780	422,395
Total liabilities and stockholders' equity	1,291,684	1,332,000
Software
Non-current assets:
Intangible assets	23,818	26,453
Acquired customer contracts
Non-current assets:
Intangible assets	$ 52,995	$ 48,012