Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Current assets:
Cash and cash equivalents	$ 51,230	$ 63,902
Short-term marketable securities	284,006	244,828
Accounts receivable	51,313	67,205
Prepaid expenses and other current assets	15,299	4,454
Total current assets	401,848	380,389
Long-term marketable securities	65,013	16,389
Property and equipment, net	10,927	8,374
Deferred tax assets	11,341	8,375
Restricted cash	608	608
Other long-term assets	92	92
Total assets	489,829	414,227
Current liabilities:
Accounts payable	6,689	4,745
Accrued expenses and other current liabilities	15,920	9,892
Income taxes payable		1,388
Total current liabilities	22,609	16,025
Series 1 nonconvertible preferred stock	1,628	1,628
Other long-term liabilities	3,100	2,895
Total liabilities	27,337	20,548
Commitments and contingencies (Note 12)
Stockholders' equity:
Common stock; $0.01 par value per share, 100,000 shares authorized; 19,703 and 19,395 shares issued and outstanding at September 30, 2019 and September 30, 2018, respectively	197	194
Additional paid-in capital	298,409	276,526
Accumulated other comprehensive income (loss)	146	(398)
Retained earnings	163,740	117,357
Total stockholders' equity	462,492	393,679
Total liabilities and stockholders' equity	$ 489,829	$ 414,227