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

6 Months Ended

Jun. 30, 2018

Available-for-Sale Securities and Fair Value Measurements

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

	June 30, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(In thousands)	Cost		Gains		Losses		Fair Value
U.S. corporate notes	$	3,879	$	—	$	(10)	$	3,869
U.S. commercial paper		16,447		—		—		16,447
Money market funds		81,426		—		—		81,426
Total	$	101,752	$	—	$	(10)	$	101,742

	December 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(In thousands)	Cost		Gains		Losses		Fair Value
U.S. government securities	$	9,943	$	—	$	(1)	$	9,942
U.S. government agencies		9,987		—		(2)		9,985
U.S. corporate notes		10,881		—		(15)		10,866
U.S. commercial papers		29,945		—		—		29,945
Money market funds		61,971		—		—		61,971
Total	$	122,727	$	—	$	(18)	$	122,709

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

	Estimated Fair Value Measurements as of June 30, 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. corporate notes	$	—	$	3,869	$	—	$	3,869
U.S. commercial paper		—		16,447		—		16,447
Money market funds		81,426		—		—		81,426
Total assets measured at estimated fair value	$	81,426	$	20,316	$	—	$	101,742
Liabilities
Term B Loan	$	—	$	123,750	$	—	$	123,750
2023 Notes		—		226,525		—		226,525
2025 Notes		—		202,146		—		202,146
Total fair value of liabilities	$	—	$	552,421	$	—	$	552,421

	Estimated Fair Value Measurements as of December 31, 2017 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	$	—	$	9,942	$	—	$	9,942
U.S. government agencies		—		9,985		—		9,985
U.S. corporate notes		—		10,866		—		10,866
U.S. commercial papers		—		29,945		—		29,945
Money market funds		61,971		—		—		61,971
Total assets measured at estimated fair value	$	61,971	$	60,738	$	—	$	122,709
Liabilities
Term B Loan	$	—	$	243,750	$	—	$	243,750
2023 Notes		—		241,259		—		241,259
2025 Notes		—		205,975		—		205,975
Total fair value of liabilities	$	—	$	690,984	$	—	$	690,984