Balance Sheet Details

12 Months Ended

Dec. 31, 2020

Condensed Financial Information Disclosure [Abstract]

4. Balance Sheet Details

Short-Term Marketable Securities

Short-term marketable securities, consisting of debt securities, were as follows as of the dates indicated:


	December 31, 2020
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Market Value
Debt securities, available for sale:
U.S. government agencies	$	1,570.4	$	0.1	$	(0.1)	$	1,570.4
Commercial paper	258.7		0.1		—		258.8
Corporate debt	60.9		—		—		60.9
Total debt securities, available for sale	$	1,890.0	$	0.2	$	(0.1)	$	1,890.1


	December 31, 2019
(In millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Market Value
Debt securities, available for sale:
U.S. government agencies	$	675.6	$	0.4	$	—	$	676.0
Commercial paper	248.1		0.1		—		248.2
Corporate debt	163.0		—		(0.1)		162.9
Total debt securities, available for sale	$	1,086.7	$	0.5	$	(0.1)	$	1,087.1

As of December 31, 2020 and 2019, all of our debt securities had contractual maturities of less than twelve months. Gross realized gains and losses on sales of our debt securities for the twelve months ended December 31, 2020, 2019 and 2018 were not significant.

We periodically review our portfolio of debt securities to determine if any investment is impaired due to credit loss or other potential valuation concerns. For debt securities where the fair value of the investment is less than the amortized cost basis, we have assessed at the individual security level for various quantitative factors including, but not limited to, the nature of the investments, changes in credit ratings, interest rate fluctuations, industry analyst reports, and the severity of impairment. Unrealized losses on available-for-sale debt securities at December 31, 2020 were not significant and were primarily due to changes in interest rates, including market credit spreads, and not due to increased credit risks associated with specific securities. Accordingly, we have not recorded an allowance for credit losses. We do not intend to sell these investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity.

The following table reconciles the net gain recognized on marketable equity securities during the twelve months ended December 31, 2020, 2019 and 2018 to the unrealized gain recognized during those periods on equity securities still held at the reporting dates.


	Twelve Months Ended December 31,
(In millions)	2020		2019		2018
Net gains and losses recognized during the period on equity securities	$	—	$	(4.2)	$	80.1
Less: Net gains and losses recognized during the period on equity securities sold during the period	—		4.2		(44.1)
Unrealized gains recognized during the reporting period on equity securities still held at the reporting date	$	—	$	—	$	36.0

Accounts Receivable


	December 31,
(In millions)	2020		2019
Accounts receivable	$	435.7	$	292.1
Less allowance for doubtful accounts	(7.2)		(5.8)
Total accounts receivable, net	$	428.5	$	286.3

Inventory


	December 31,
(In millions)	2020		2019
Raw materials	$	69.9	$	64.9
Work-in-process	14.2		11.1
Finished goods	150.6		43.8
Total inventory	$	234.7	$	119.8

During the twelve months ended December 31, 2020 and 2019, we recorded excess and obsolete inventory charges of $24.4 million and $14.1 million, respectively, in cost of sales as a result of our ongoing assessment of sales demand, inventory on hand for each product and the continuous improvement and innovation of our products. During the twelve months ended December 31, 2018, we recorded excess and obsolete inventory charges of $7.3 million in cost of sales primarily as a result of the approval and launch of our G6 system and our ongoing assessment of sales demand and the continuous improvement and innovation of our products.

Property and Equipment


	December 31,
(In millions)	2020		2019
Land (1)	$	15.6	$	—
Building (1)	49.2		15.5
Furniture and fixtures	15.3		12.8
Computer software and hardware	35.7		32.7
Machinery and equipment	198.9		130.2
Leasehold improvements	135.8		102.5
Construction in progress	219.0		132.6
Total cost	669.5		426.3
Less accumulated depreciation and amortization	(154.2)		(105.0)
Total property and equipment, net	$	515.3	$	321.3

(1) Represents our finance lease right-of-use assets.

Depreciation expense related to property and equipment for the twelve months ended December 31, 2020, 2019 and 2018 was $64.0 million, $46.9 million, and $28.6 million, respectively.

Loss on disposal of property and equipment during the twelve months ended December 31, 2020, 2019 and 2018 recorded in operating expenses was $13.6 million, $10.5 million and $5.4 million, respectively.

Accounts Payable and Accrued Liabilities


	December 31,
(In millions)	2020		2019
Accounts payable trade	$	163.3	$	102.3
Accrued tax, audit, and legal fees	15.3		14.0
Accrued rebates	247.0		93.3
Accrued warranty	11.7		7.4

Other accrued liabilities	43.8		39.4
Total accounts payable and accrued liabilities	$	481.1	$	256.4

Accrued Warranty

Warranty costs are reflected in our statements of operations as cost of sales. Reconciliations of our accrued warranty costs for the twelve months ended December 31, 2020 and 2019 were as follows:


	Twelve Months Ended December 31,
(In millions)	2020		2019
Beginning balance	$	7.4	$	6.8
Charges to costs and expenses	41.3		32.7
Costs incurred	(37.0)		(32.1)
Ending balance	$	11.7	$	7.4

Other Long-Term Liabilities


	December 31,
(In millions)	2020		2019
Finance lease obligations	$	54.0	$	14.4
Contractual obligations	12.6		—
Other liabilities	14.3		5.7
Total other liabilities	$	80.9	$	20.1