Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Investments Measured at Fair Value on Recurring Basis

Investments, which were measured at fair value on a recurring basis using the inputs described above, consisted of the following:

	blank			Fair Value Measurements Using
(in millions)	Carrying Value			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
March 31, 2019:
Classified as current assets:
Cash and money market funds	$	72.8		$	72.8		$	—	$	—
Commercial paper		97.5			—			97.5		—
Securities of government-sponsored entities		45.8			—			45.8		—
Corporate debt securities		308.0			—			308.0		—
Subtotal		524.1			72.8			451.3		—
Classified as long-term assets:
Cash and money market funds		1.5			1.5			—		—
Certificates of deposit		4.0			4.0			—		—
Securities of government-sponsored entities		43.1			—			43.1		—
Corporate debt securities		133.6			—			133.6		—
Restricted equity securities		56.4			—			—		56.4
Total		762.7			78.3			628.0		56.4
Less cash and cash equivalents and restricted cash		(78.3	)		(78.3	)		—		—
Total investments	$	684.4		$	—		$	628.0	$	56.4
blank
December 31, 2018:
Classified as current assets:
Cash and money market funds	$	141.7		$	141.7		$	—	$	—
Commercial paper		94.6			—			94.6		—
Securities of government-sponsored entities		20.8			—			20.8		—
Corporate debt securities		393.8			—			393.8		—
Subtotal		650.9			141.7			509.2		—
Classified as long-term assets:
Cash and money market funds		1.5			1.5			—		—
Certificates of deposit		4.0			4.0			—		—
Securities of government-sponsored entities		64.8			—			64.8		—
Corporate debt securities		151.2			—			151.2		—
Total		872.4			147.2			725.2		—
Less cash and cash equivalents and restricted cash		(147.2	)		(147.2	)		—		—
Total investments	$	725.2		$	—		$	725.2	$	—

Reconciliation of Our Investment in Restricted Equity Securities Measured at Fair Value on Quarterly Basis Using Significant Unobservable Inputs (Level 3)

The following table presents a reconciliation of our investment in restricted equity securities measured at fair value on a quarterly basis using significant unobservable inputs (Level 3):

(in millions)
Balance at December 31, 2018	$	—
Investment in restricted equity securities		54.7
Unrealized gain recognized on restricted equity securities still held at March 31, 2019		1.7
Balance at March 31, 2019	$	56.4