Available-for-Sale Securities and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Available-for-Sale Securities and Fair Value Measurements

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

	September 30, 2019
			Gross		Gross
			Unrealized		Unrealized		Estimated
(In thousands)	Amortized Cost		Gains		Losses		Fair Value
U.S. government securities	$	91,440	$	26	$	(1)	$	91,465
U.S. commercial paper		54,356		—		—		54,356
Money market funds		101,636		—		—		101,636
Total	$	247,432	$	26	$	(1)	$	247,457

	December 31, 2018
			Gross		Gross
			Unrealized		Unrealized		Estimated
(In thousands)	Amortized Cost		Gains		Losses		Fair Value
U.S. government securities	$	29,736	$	—	$	(3)	$	29,733
U.S. government agencies		4,971		—		—		4,971
U.S. corporate notes		2,875		—		—		2,875
U.S. commercial paper		22,037		—		—		22,037
Money market funds		49,358		—		—		49,358
Total	$	108,977	$	—	$	(3)	$	108,974

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

	Estimated Fair Value Measurements as of September 30, 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	$	—	$	91,465	$	—	$	91,465
U.S. commercial paper		—		54,356		—		54,356
Money market funds		101,636		—		—		101,636
Total assets measured at estimated fair value	$	101,636	$	145,821	$	—	$	247,457
Debt
Term B Loan	$	—	$	13,750	$	—	$	13,750
2023 Notes		—		226,139		—		226,139
2025 Notes		—		182,729		—		182,729
Total fair value of debt	$	—	$	422,618	$	—	$	422,618

	Estimated Fair Value Measurements as of December 31, 2018 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	$	—	$	29,733	$	—	$	29,733
U.S. government agencies		—		4,971		—		4,971
U.S. corporate notes		—		2,875		—		2,875
U.S. commercial paper		—		22,037		—		22,037
Money market funds		49,358		—		—		49,358
Total assets measured at estimated fair value	$	49,358	$	59,616	$	—	$	108,974
Debt
Term B Loan	$	—	$	13,750	$	—	$	13,750
2023 Notes		—		258,918		—		258,918
2025 Notes		—		230,692		—		230,692
Total fair value of debt	$	—	$	503,360	$	—	$	503,360