UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 139,878	$ 171,899
Marketable securities	271,459	293,269
Total cash, cash equivalents, and marketable securities	411,337	465,168
Accounts receivable	166,226	215,827
Unbilled receivables	236,451	207,155
Other current assets	96,215	88,760
Total current assets	910,229	976,910
Unbilled receivables	144,065	113,278
Goodwill	82,173	79,231
Other long-term assets	466,103	434,843
Total assets	1,602,570	1,604,262
Current liabilities:
Accounts payable	22,931	24,028
Accrued expenses	64,093	59,261
Accrued compensation and related expenses	84,900	123,012
Deferred revenue	242,194	232,865
Other current liabilities	16,126	20,969
Total current liabilities	430,244	460,135
Convertible senior notes, net	589,092	518,203
Operating lease liabilities	42,063	59,053
Other long-term liabilities	18,703	24,699
Total liabilities	1,080,102	1,062,090
Stockholders’ equity:
Preferred stock, 1,000 shares authorized; none issued	0	0
Common stock, 200,000 shares authorized; 81,456 and 80,890 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	815	809
Additional paid-in capital	147,670	204,432
Retained earnings	375,069	339,879
Accumulated other comprehensive (loss)	(1,086)	(2,948)
Total stockholders’ equity	522,468	542,172
Total liabilities and stockholders’ equity	$ 1,602,570	$ 1,604,262