CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 237,170	$ 62,436
Available-for-sale debt securities, at fair value (amortized cost $218,596, allowance for credit losses of $0 as of June 30, 2020; amortized cost $335,206, allowance for credit losses of $0 as of December 31, 2019)	220,206	336,088
Accounts receivable, net	14,077	18,048
Inventory, net	6,286	6,082
Prepaid expenses and other current assets	7,714	5,015
Tax receivable	20,109	1,395
Total current assets	505,562	429,064
Property and equipment, net	2,930	2,891
Other non-current assets	13,895	14,709
Intangible assets, net	155,371	157,200
Goodwill	936	936
Total assets	678,694	604,800
Current liabilities:
Accounts payable	10,198	26,614
Accrued expenses	44,379	51,745
Other current liabilities	7,356	8,590
Business combination-related contingent consideration	8,000	8,500
Total current liabilities	69,933	95,449
Convertible debt	210,009	204,861
Other non-current liabilities	19,507	20,894
Business combination-related contingent consideration, less current portion	60,600	62,400
Total liabilities	360,049	383,604
Stockholders' Equity:
Preferred stock $0.0001 par value; 20,000,000 shares authorized; 0 issued and outstanding as of June 30, 2020 and December 31, 2019	0	0
Common stock $0.0001 par value; 100,000,000 shares authorized; 50,902,874 and 43,088,921 issued and outstanding as of June 30, 2020 and December 31, 2019, respectively	5	4
Additional paid-in capital	758,945	636,910
Accumulated deficit	(441,704)	(416,444)
Accumulated other comprehensive income	1,399	726
Total stockholders' equity	318,645	221,196
Total liabilities and stockholders' equity	$ 678,694	$ 604,800