CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net income	$ 9,200	$ 10,914
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	694	672
Stock-based compensation	7,013	6,383
Amortization of premiums and accretion of discounts on marketable securities	(420)	(1,848)
Gain on sale of marketable securities	(229)	0
Intangible asset amortization	739	759
Deferred income taxes	2,019	0
Other non-cash adjustments, net	695	740
Changes in operating assets and liabilities:
Accounts receivable	1,672	4,851
Prepaid expenses and other assets	(591)	681
Inventory	10	(191)
Accounts payable and other liabilities	883	5,159
Product revenue allowances	1,414	2,038
Net cash provided by operating activities	23,099	30,158
Cash flows from investing activities
Purchases of property and equipment	(583)	(657)
Purchases of marketable securities	(151,124)	(191,293)
Sales and maturities of marketable securities	174,739	143,745
Net cash provided by (used in) investing activities	23,032	(48,205)
Cash flows from financing activities
Proceeds from the exercise of stock options	4,079	3,590
Net cash provided by financing activities	4,079	3,590
Effect of exchange rate changes on cash, cash equivalents and restricted cash	23	(5)
Net change in cash, cash equivalents and restricted cash	50,233	(14,462)
Cash, cash equivalents and restricted cash
Beginning of period	45,650	61,749
End of period	$ 95,883	$ 47,287