Financial Instruments and Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Financial Instruments and Fair Value Measurements

Schedule of amortized cost and estimated fair values for available-for-sale securities

	June 30, 2020
			Gross		Gross
			Unrealized		Unrealized		Estimated
(In thousands)	Amortized Cost		Gains		Losses		Fair Value
U.S. government securities	$	3,993	$	6	$	—	$	3,999
Money market funds		378,472		—		—		378,472
Total	$	382,465	$	6	$	—	$	382,471

	December 31, 2019
			Gross		Gross
			Unrealized		Unrealized		Estimated
(In thousands)	Amortized Cost		Gains		Losses		Fair Value
U.S. government securities	$	53,799	$	35	$	—	$	53,834
U.S. commercial paper		18,915		—		—		18,915
Money market funds		233,992		—		—		233,992
Total	$	306,706	$	35	$	—	$	306,741

Schedule of available-for-sale securities measured at fair value on a recurring basis

	Estimated Fair Value Measurements as of June 30, 2020 Using:
	Quoted Price in
	Active Markets		Significant Other		Significant
	for Identical		Observable		Unobservable
Types of Instruments	Assets		Inputs		Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
U.S. government securities	$	—	$	3,999	$	—	$	3,999
Money market funds		378,472		—		—		378,472
Equity investment - Armata Common Stock		34,146		—		—		34,146
Equity investment - Armata Warrants		—		26,181		—		26,181
Equity investment - Entasis Common Stock		41,440		—		—		41,440
Equity investment - Entasis Warrants		—		26,846		—		26,846
Total assets measured at estimated fair value	$	454,058	$	57,026	$	—	$	511,084
Debt
2023 Notes	$	—	$	246,303	$	—	$	246,303
2025 Notes		—		198,997		—		198,997
Total fair value of debt	$	—	$	445,300	$	—	$	445,300

	Estimated Fair Value Measurements as of December 31, 2019 Using:
	Quoted Price in
	Active Markets		Significant Other		Significant
	for Identical		Observable		Unobservable
Types of Instruments	Assets		Inputs		Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
U.S. government securities	$	—	$	53,834	$	—	$	53,834
U.S. commercial paper		—		18,915		—		18,915
Money market funds		233,992		—		—		233,992
Total assets measured at estimated fair value	$	233,992	$	72,749	$	—	$	306,741
Debt
2023 Notes	$	—	$	243,394	$	—	$	243,394
2025 Notes		—		208,976		—		208,976
Total fair value of debt	$	—	$	452,370	$	—	$	452,370