Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 187.0	$ 112.3
Debt securities available-for-sale, at fair value (amortized cost $584.1 million at March 31, 2020 and $557.3 million at December 31, 2019)	584.7	558.2
Accounts receivable	148.6	126.6
Inventories	21.2	17.3
Other current assets	26.7	16.6
Total current assets	968.2	831.0
Debt securities available-for-sale, at fair value (amortized cost $237.8 million at March 31, 2020 and $299.3 million at December 31, 2019)	235.9	299.7
Right-of-use assets	73.3	74.3
Equity securities	39.4	55.9
Property and equipment, net	41.9	41.9
Restricted cash	3.2	3.2
Total assets	1,361.9	1,306.0
Current liabilities:
Accounts payable and accrued liabilities	125.9	141.3
Convertible senior notes		408.8
Other current liabilities	14.4	15.2
Total current liabilities	140.3	565.3
Convertible senior notes	414.1	408.8
Operating lease liabilities	85.6	86.7
Other long-term liabilities	21.6	17.1
Total liabilities	661.6	669.1
Stockholders’ equity:
Preferred stock, $0.001 par value; 5.0 shares authorized; no shares issued and outstanding at March 31, 2020 and December 31, 2019
Common stock, $0.001 par value; 220.0 shares authorized; issued and outstanding shares were 92.8 at March 31, 2020 and 92.3 at December 31, 2019	0.1	0.1
Additional paid-in capital	1,796.9	1,768.1
Accumulated other comprehensive (loss) income	(1.4)	1.4
Accumulated deficit	(1,095.3)	(1,132.7)
Total stockholders’ equity	700.3	636.9
Total liabilities and stockholders’ equity	$ 1,361.9	$ 1,306.0