UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 95,500	$ 114,422
Marketable securities	59,549	93,001
Total cash, cash equivalents, and marketable securities	155,049	207,423
Accounts receivable	134,965	180,872
Unbilled receivables	169,554	172,656
Other current assets	77,290	49,684
Total current assets	536,858	610,635
Long-term unbilled receivables	117,889	151,237
Goodwill	79,037	72,858
Other long-term assets	206,833	147,823
Total assets	940,617	982,553
Current liabilities:
Accounts payable	14,586	16,487
Accrued expenses	50,372	45,506
Accrued compensation and related expenses	62,880	84,671
Deferred revenue	169,009	185,145
Other current liabilities	14,576	0
Total current liabilities	311,423	331,809
Operating lease liabilities	54,292	0
Deferred income tax liabilities	6,918	6,939
Other long-term liabilities	10,697	22,274
Total liabilities	383,330	361,022
Stockholders’ equity:
Preferred stock, 1,000 shares authorized; none issued	0	0
Common stock, 200,000 shares authorized; 79,144 and 78,526 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	791	785
Additional paid-in capital	122,880	123,205
Retained earnings	445,108	510,863
Accumulated other comprehensive (loss)	(11,492)	(13,322)
Total stockholders’ equity	557,287	621,531
Total liabilities and stockholders’ equity	$ 940,617	$ 982,553