Investments (Tables) - Available-for-Sale Debt Securities

3 Months Ended

Mar. 31, 2020

Investments

Schedule of available-for-sale debt securities

Available-for-sale debt securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive income in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions):

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
As of March 31, 2020	Cost		Gains		Losses		Value
U.S. government and agency securities	$	1,251.2	$	17.9	$	(0.1)	$	1,269.0
Corporate debt securities		244.7		0.7		(0.9)		244.5
Total	$	1,495.9	$	18.6	$	(1.0)	$	1,513.5
Reported under the following captions on our consolidated balance sheets:
Current marketable investments								645.5
Non-current marketable investments								868.0
Total							$	1,513.5

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
As of December 31, 2019	Cost		Gains		Losses		Value
U.S. government and agency securities	$	1,225.2	$	2.9	$	(0.2)	$	1,227.9
Corporate debt securities		222.4		1.7		—		224.1
Total	$	1,447.6	$	4.6	$	(0.2)	$	1,452.0
Reported under the following captions on our consolidated balance sheets:
Current marketable investments								684.5
Non-current marketable investments								767.5
Total							$	1,452.0

Summary of the contractual maturities

The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions):

	As of March 31, 2020
	Amortized		Fair
	Cost		Value
Due within one year	$	641.3	$	645.5
Due in one to three years		854.6		868.0
Total	$	1,495.9	$	1,513.5

	As of December 31, 2019
	Amortized		Fair
	Cost		Value
Due within one year	$	683.3	$	684.5
Due in one to three years		764.3		767.5
Total	$	1,447.6	$	1,452.0