Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash Flows from Operating Activities:
Net income	$ 59.4	$ 3.0
Reconciliation of net income to net cash provided by operating activities:
Share-based compensation expense	79.0	54.0
Depreciation	6.4	5.4
Amortization of debt discount	15.2	14.1
Amortization of debt issuance costs	1.0	1.0
Change in fair value of equity security investments	12.2	5.8
Other	1.7	(0.7)
Change in operating assets and liabilities:
Accounts receivable	(30.3)	(57.9)
Inventories	(3.4)	0.1
Accounts payable and accrued liabilities	28.1	12.3
Other assets and liabilities, net	(29.7)	12.4
Net cash provided by operating activities	139.6	49.5
Cash Flows from Investing Activities:
Purchases of debt securities available-for-sale	(399.2)	(467.1)
Sales and maturities of debt securities available-for-sale	557.4	488.8
Purchases of equity securities	0.0	(54.7)
Purchases of property and equipment	(6.4)	(11.9)
Net cash provided by (used in) investing activities	151.8	(44.9)
Cash Flows from Financing Activities:
Issuance of common stock	21.6	20.0
Net cash provided by financing activities	21.6	20.0
Change in cash, cash equivalents and restricted cash	313.0	24.6
Cash, cash equivalents and restricted cash at beginning of period	115.5	147.2
Cash, cash equivalents and restricted cash at end of period	428.5	171.8
Supplemental Disclosure:
Non-cash capital expenditures	1.1	0.1
Cash paid for interest	5.8	5.8
Cash paid for income taxes	$ 0.4	$ 0.5