Financial Instruments and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2020

Financial Instruments and Fair Value Measurements

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

Available-for-sale securities are summarized below:

	September 30, 2020
			Gross		Gross
			Unrealized		Unrealized		Estimated
(In thousands)	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	430,144	$	—	$	—	$	430,144
Total	$	430,144	$	—	$	—	$	430,144

	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

The estimated fair values were as follows:

	Estimated Fair Value Measurements as of September 30, 2020 Using:
	Quoted Price		Significant
	in Active		Other		Significant
	Markets for		Observable		Unobservable
Types of Instruments	Identical Assets		Inputs		Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	430,144	$	—	$	—	$	430,144
Equity investment - Armata Common Stock		27,787		—		—		27,787
Equity investment - Armata Warrants		—		20,167		—		20,167
Equity investment - Entasis Common Stock		38,093		—		—		38,093
Equity investment - Entasis Warrants		—		25,698		—		25,698
Total assets measured at estimated fair value	$	496,024	$	45,865	$	—	$	541,889
Debt
2023 Notes	$	—	$	230,494	$	—	$	230,494
2025 Notes		—		191,491		—		191,491
Total fair value of debt	$	—	$	421,985	$	—	$	421,985

	Estimated Fair Value Measurements as of December 31, 2019 Using:
	Quoted Price		Significant
	in Active		Other		Significant
	Markets for		Observable		Unobservable
Types of Instruments	Identical 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