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

9 Months Ended

Sep. 30, 2017

Available-for-Sale Securities and Fair Value Measurements

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

	September 30, 2017
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government agencies	$	9,959	$	—	$	—		$	9,959
U.S. corporate notes	9,879		—		(3		)	9,876
U.S. commercial paper	24,582		—		—			24,582
Money market funds	118,163		—		—			118,163
Total	$	162,583	$	—	$	(3	)	$	162,580

	December 31, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. government agencies	$	12,428	$	1	$	—	$	12,429
U.S. commercial paper	72,065		—		—		72,065
Money market funds	64,319		—		—		64,319
Total	$	148,812	$	1	$	—	$	148,813

Schedule of estimated fair values by hierarchy

	Estimated Fair Value Measurements as of September 30, 2017 Using:
Types of Instruments	Quoted Price in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
U.S. government agencies	$	—	$	9,959	$	—	$	9,959
U.S. corporate notes	—		9,876		—		9,876
U.S. commercial paper	—		24,582		—		24,582
Money market funds	118,163		—		—		118,163
Total assets measured at estimated fair value	$	118,163	$	44,417	$	—	$	162,580
Liabilities
Term B Loan	$	—	$	250,000	$	—	$	250,000
2023 Notes	—		234,658		—		234,658
2025 Notes	—		202,125		—		202,125
Total fair value of liabilities	$	—	$	686,783	$	—	$	686,783

	Estimated Fair Value Measurements as of December 31, 2016 Using:
Types of Instruments	Quoted Price in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(In thousands)	Level 1		Level 2		Level 3		Total
Assets
U.S. government agencies	$	—	$	12,429	$	—	$	12,429
U.S. commercial paper	—		72,065		—		72,065
Money market funds	64,319		—		—		64,319
Total assets measured at estimated fair value	$	64,319	$	84,494	$	—	$	148,813
Liabilities
2023 Notes	$	—	$	202,125	$	—	$	202,125
2029 Notes	—		487,189		—		487,189
Total fair value of liabilities	$	—	$	689,314	$	—	$	689,314