Marketable Securities

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Marketable SecuritiesThe proceeds from maturities and sales of available-for-sale debt securities and resulting realized gains and losses are summarized below. In the second quarter of 2020, we liquidated all of our available-for-sale debt securities to fund the acquisition of Portola. Additionally, we liquidated all available-for-sale debt securities acquired in connection with the Portola acquisition.


	Three months ended				Nine months ended
	September 30,				September 30,
	2020		2019		2020		2019
Proceeds from maturities and sales (1)	$	25.5	$	645.4	$	1,042.4	$	2,271.7
Realized gains	$	—	$	—	$	—	$	—
Realized losses	$	—	$	—	$	—	$	—
(1) Proceeds from maturities and sales of available-for-sale debt securities include securities previously classified as cash and cash equivalents and marketable securities in the condensed consolidated balance sheet.

We utilize the specific identification method in computing realized gains and losses.

As a result of our liquidation of all available-for-sale debt securities during the second and third quarters of 2020, we have no remaining available-for-sale debt securities as of September 30, 2020. The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value of available-for-sale debt securities by type of security as of December 31, 2019 were as follows:


	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
Commercial paper	$	246.9	$	—	$	—	$	246.9
Corporate bonds	24.3		—		—		24.3
Other government-related obligations:
U.S.	70.4		—		—		70.4
Bank certificates of deposit	27.4		—		—		27.4
Total available-for-sale debt securities	$	369.0	$	—	$	—	$	369.0

The aggregate fair value of available-for-sale debt securities in an unrealized loss position as of December 31, 2019 was $21.5. We did not have any investments in a continuous unrealized loss position for more than twelve months as of December 31, 2019.

The fair values of available-for-sale debt securities by classification in the condensed consolidated balance sheets were as follows:


	September 30, 2020		December 31, 2019
Cash and cash equivalents	$	—	$	328.1
Marketable securities	—		40.9
	$	—	$	369.0

We sponsor a nonqualified deferred compensation plan which allows certain highly-compensated employees to elect to defer income to future periods. Participants in the plan earn a return on their deferrals based on several investment options, which mirror returns on underlying mutual fund investments. We choose to invest in the underlying mutual fund investments to offset the liability associated with our nonqualified deferred compensation plan. These mutual fund investments are valued at net asset value per share and are carried at fair value with gains and losses included in investment income. The changes in the underlying liability to the employee are recorded in operating expenses. As of September 30, 2020 and December 31, 2019, the fair value of these investments was $28.9 and $23.1, respectively.