CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 122,243	$ 126,351
Short-term investments	139,117	150,147
Total cash, cash equivalents and short-term investments	261,360	276,498
Trade accounts receivable:
Billed, net of allowance of $4,149 and $3,080	219,531	208,930
Unbilled	31,187	30,828
Income taxes receivable	13,839	11,931
Other current assets	28,349	30,386
Total current assets	554,266	558,573
Non-current assets:
Property and equipment, net of depreciation of $123,126 and $122,866	44,651	33,116
Goodwill	210,080	201,094
Deferred income taxes	14,057	14,218
Other assets	10,948	13,776
Total non-current assets	350,268	333,306
Total assets	904,534	891,879
Current liabilities:
Current portion of long-term debt, net of unamortized discounts of zero and $296	22,500	49,426
Client deposits	31,053	33,916
Trade accounts payable	38,420	35,118
Accrued employee compensation	62,984	65,341
Deferred revenue	41,885	45,064
Income taxes payable	1,216	822
Other current liabilities	24,535	22,342
Total current liabilities	222,593	252,029
Non-current liabilities:
Long-term debt, net of unamortized discounts of $18,264 and $23,007	309,236	326,993
Deferred revenue	12,346	6,694
Income taxes payable	2,415	2,245
Deferred income taxes	4,584	99
Other non-current liabilities	10,614	12,618
Total non-current liabilities	339,195	348,649
Total liabilities	561,788	600,678
Current portion of long-term debt conversion obligation		39,841
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; 2,702 and 3,971 shares reserved for employee stock purchase plan and stock incentive plans; 33,516 and 32,261 shares outstanding	689	672
Common stock warrants; 439 and 1,426 warrants vested; 1,425 and 2,851 issued	9,082	16,007
Additional paid-in capital	427,091	391,209
Treasury stock, at cost; 34,075 and 34,919 shares	(814,732)	(826,002)
Accumulated other comprehensive income (loss):
Unrealized loss on short-term investments, net of tax	(88)	(159)
Cumulative foreign currency translation adjustments	(28,734)	(45,213)
Accumulated earnings	749,438	714,846
Total stockholders' equity	342,746	251,360
Total liabilities, current portion of long-term debt conversion obligation and stockholders' equity	904,534	891,879
Software
Non-current assets:
Intangible assets	26,906	30,427
Client contracts
Non-current assets:
Intangible assets	$ 43,626	$ 40,675