CONDENSED CONSOLIDATED BALANCE SHEETS - UNAUDITED - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 147,503	$ 122,243
Short-term investments	74,595	139,117
Total cash, cash equivalents and short-term investments	222,098	261,360
Trade accounts receivable:
Billed, net of allowance of $3,967 and $4,149	213,051	219,531
Unbilled	35,426	31,187
Income taxes receivable	12,261	13,839
Other current assets	32,388	28,349
Total current assets	515,224	554,266
Non-current assets:
Property and equipment, net of depreciation of $109,074 and $123,126	59,553	44,651
Intangible assets	70,582
Goodwill	222,915	210,080
Client contract costs, net of amortization of $25,304 and zero	38,357
Deferred income taxes	13,844	14,057
Other assets	7,963	10,948
Total non-current assets	413,214	350,268
Total assets	928,438	904,534
Current liabilities:
Current portion of long-term debt	7,500	22,500
Client deposits	34,991	31,053
Trade accounts payable	35,536	38,420
Accrued employee compensation	46,027	62,984
Deferred revenue	38,197	41,885
Income taxes payable	1,502	1,216
Other current liabilities	20,948	24,535
Total current liabilities	184,701	222,593
Non-current liabilities:
Long-term debt, net of unamortized discounts of $17,741 and $18,264	354,759	309,236
Deferred revenue	9,191	12,346
Income taxes payable	2,457	2,415
Deferred income taxes	8,412	4,584
Other non-current liabilities	10,843	10,614
Total non-current liabilities	385,662	339,195
Total liabilities	570,363	561,788
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; 33,674 and 33,516 shares outstanding	692	689
Common stock warrants; 439 and 439 warrants vested; 1,425 and 1,425 issued	9,082	9,082
Additional paid-in capital	425,926	427,091
Treasury stock, at cost; 34,200 and 34,075 shares	(820,434)	(814,732)
Accumulated other comprehensive income (loss):
Unrealized loss on short-term investments, net of tax	(182)	(88)
Cumulative foreign currency translation adjustments	(21,024)	(28,734)
Accumulated earnings	764,015	749,438
Total stockholders' equity	358,075	342,746
Total liabilities and stockholders' equity	928,438	904,534
Software
Non-current assets:
Intangible assets	30,894	26,906
Client contracts
Non-current assets:
Intangible assets		$ 43,626
Acquired client contracts
Non-current assets:
Intangible assets	$ 39,688