Fair Value Measurements

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

Investments at March 31, 2020, which were measured at fair value on a recurring basis, consisted of the following:

			Fair Value Measurements Using
(in millions)	Fair Value		Level 1		Level 2		Level 3
Cash and cash equivalents:
Cash and money market funds	$	187.0	$	187.0	$	—	$	—
Total cash and cash equivalents		187.0		187.0		—		—
Restricted cash:
Certificates of deposit		3.2		3.2		—		—
Total restricted cash		3.2		3.2		—		—
Debt securities available-for-sale:
Commercial paper		129.7		—		129.7		—
Corporate debt securities		534.0		—		534.0		—
Securities of government-sponsored entities		156.9		—		156.9		—
Total debt securities available-for-sale		820.6		—		820.6		—
Equity securities:
Equity securities–biotechnology industry		39.4		—		—		39.4
Total equity securities		39.4		—		—		39.4
Total recurring fair value measurements	$	1,050.2	$	190.2	$	820.6	$	39.4

Investments at December 31, 2019, which were measured at fair value on a recurring basis, consisted of the following:

			Fair Value Measurements Using
(in millions)	Fair Value		Level 1		Level 2		Level 3
Cash and cash equivalents:
Cash and money market funds	$	112.3	$	112.3	$	—	$	—
Total cash and cash equivalents		112.3		112.3		—		—
Restricted cash:
Certificates of deposit		3.2		3.2		—		—
Total restricted cash		3.2		3.2		—		—
Debt securities available-for-sale:
Commercial paper		144.5		—		144.5		—
Corporate debt securities		521.9		—		521.9		—
Securities of government-sponsored entities		191.5		—		191.5		—
Total debt securities available-for-sale		857.9		—		857.9		—
Equity securities:
Equity securities–biotechnology industry		55.9		—		—		55.9
Total equity securities		55.9		—		—		55.9
Total recurring fair value measurements	$	1,029.3	$	115.5	$	857.9	$	55.9

The following table presents a reconciliation of equity securities for the three months ended March 31, 2020, which were measured at fair value on a recurring basis using significant unobservable inputs (Level 3):

(in millions)	Equity Securities
Fair value at December 31, 2019	$	55.9
Purchases		—
Unrealized losses included in earnings		(16.5	)
Fair value at March 31, 2020	$	39.4

At March 31, 2020, the discount for lack of marketability used in the valuation analysis of equity securities ranged from 18.5% to 30.0% (weighted average of 26.2%). The discount for lack of marketability was weighted by the relative fair value of the instruments. A significant increase (decrease) in the discount for lack of marketability in isolation would result in a significantly lower (higher) fair value measurement. Unrealized gains and losses on equity securities are included in other expense, net.

The following table presents a reconciliation of equity securities for the three months ended March 31, 2019, which were measured at fair value on a recurring basis using significant unobservable inputs (Level 3):

(in millions)	Equity Securities
Fair value at December 31, 2018	$	—
Purchases		54.7
Unrealized gains included in earnings		1.7
Fair value at March 31, 2019	$	56.4