Debt Securities (Tables)

6 Months Ended

Jun. 30, 2024

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost, Gross Unrealized Gains and Losses, Allowance for Credit Losses and Fair Value of Debt Securities Available-For-Sale

The following table presents the amortized cost, unrealized gain and loss recognized in accumulated other comprehensive income (loss) and fair value of debt securities available-for-sale, aggregated by major security type and contractual maturity.

		June 30, 2024								December 31, 2023
(in millions)	Contractual Maturity	Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value		Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value
Commercial paper	0 to 1 years	$	57.2	$	—	$	—	$	57.2	$	53.5	$	—	$	—	$	53.5
Corporate debt securities	0 to 1 years	530.9		0.1		(1.2)		529.8		382.1		0.1		(1.0)		381.2
Securities of government-sponsored entities	0 to 1 years	312.7		—		(0.5)		312.2		346.1		0.2		(0.5)		345.8
		$	900.8	$	0.1	$	(1.7)	$	899.2	$	781.7	$	0.3	$	(1.5)	$	780.5
Corporate debt securities	1 to 3 years	$	476.4	$	0.4	$	(1.7)	$	475.1	$	483.5	$	2.9	$	(0.4)	$	486.0
Securities of government-sponsored entities	1 to 3 years	163.4		—		(0.7)		162.7		201.1		0.5		(0.1)		201.5
		$	639.8	$	0.4	$	(2.4)	$	637.8	$	684.6	$	3.4	$	(0.5)	$	687.5

Schedule of Gross Unrealized Losses and Fair Value Available-For-Sale Investments in Unrealized Loss Position

The following table presents debt securities available-for-sale that were in an unrealized loss position as of June 30, 2024, aggregated by major security type and length of time in a continuous 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	$	678.2	$	(2.3)	$	104.0	$	(0.6)	$	782.2	$	(2.9)
Securities of government-sponsored entities	$	386.7	$	(1.0)	$	51.0	$	(0.2)	$	437.7	$	(1.2)

The following table presents debt securities available-for-sale that were in an unrealized loss position as of December 31, 2023, aggregated by major security type and length of time in a continuous 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	$	265.1	$	(0.4)	$	183.8	$	(1.0)	$	448.9	$	(1.4)
Securities of government-sponsored entities	$	214.6	$	(0.2)	$	16.7	$	(0.4)	$	231.3	$	(0.6)