Debt Securities

3 Months Ended

Mar. 31, 2020

Investments Debt And Equity Securities [Abstract]

Debt Securities

3. Debt Securities

The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive loss, allowance for credit losses, and fair value of debt securities available-for-sale at March 31, 2020, aggregated by major security type and contractual maturity:

(in millions)	Contractual Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss			Allowance for Credit Losses		Fair Value
Commercial paper	Within 1 year	$	129.7	$	0.1	$	(0.1	)	$	—	$	129.7
Corporate debt securities	Within 1 year		323.3		0.3		(0.9	)		—		322.7
Securities of government-sponsored entities	Within 1 year		131.1		1.2		—			—		132.3
blank		$	584.1	$	1.6	$	(1.0	)	$	—	$	584.7
blank
Corporate debt securities	1 to 2 years	$	213.3	$	0.2	$	(2.2	)	$	—	$	211.3
Securities of government-sponsored entities	1 to 2 years		24.5		0.1		—			—		24.6
		$	237.8	$	0.3	$	(2.2	)	$	—	$	235.9

The following table summarizes the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive income, and fair value of debt securities available-for-sale at December 31, 2019, aggregated by major security type and contractual maturity:

(in millions)	Contractual Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
Commercial paper	Within 1 year	$	144.5	$	—	$	—		$	144.5
Corporate debt securities	Within 1 year		270.5		0.5		—			271.0
Securities of government-sponsored entities	Within 1 year		142.3		0.4		—			142.7
blank		$	557.3	$	0.9	$	—		$	558.2
blank
Corporate debt securities	1 to 2 years	$	250.5	$	0.5	$	(0.1	)	$	250.9
Securities of government-sponsored entities	1 to 2 years		48.8		—		—			48.8
		$	299.3	$	0.5	$	(0.1	)	$	299.7

The following table summarizes debt securities available-for-sale in an unrealized loss position for which an allowance for credit losses has not been recorded at March 31, 2020, aggregated by major security type and length of time in a continuous unrealized loss position:

	Less Than 12 Months					12 Months or Longer				Total
(in millions)	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Commercial paper	$	19.9	$	(0.1	)	$	—	$	—	$	19.9	$	(0.1	)
Corporate debt securities		409.8		(3.1	)		—		—		409.8		(3.1	)
blank	$	429.7	$	(3.2	)	$	—	$	—	$	429.7	$	(3.2	)

At March 31, 2020, our security portfolio consisted of 187 securities, of which 107 were in an unrealized loss position, related to investments in debt securities available-for-sale, as discussed below:

Commercial paper. Our investments in commercial paper are of high credit quality (rated A1 or higher). Unrealized losses on these investments were primarily due to changes in interest rates. We do not intend to sell these investments and it is not more likely than not that we will be required to sell these investments before recovery of their amortized costs basis.

Corporate debt securities. Our investments in corporate debt securities are of high credit quality (rated AA- or higher). Unrealized losses on these investments were primarily due to changes in interest rates. We do not intend to sell these investments and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost basis.

The following table summarizes debt securities available-for-sale in an unrealized loss position at December 31, 2019, aggregated by major security type and length of time in a continuous unrealized loss position:

	Less Than 12 Months					12 Months or Longer				Total
(in millions)	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate debt securities	$	186.1	$	(0.1	)	$	—	$	—	$	186.1	$	(0.1	)