Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Valuation of Company's Assets and Liabilities Measured at Fair Value

The following table summarizes the valuation of the Company’s assets and liabilities measured at fair value as categorized based on the hierarchy described in Note 2.

	Level 1		Level 2			Level 3		Total
	(In thousands)
As of September 30, 2019
Money market funds	$	163,734	$	—		$	—	$	163,734
Securities available-for-sale
Corporate debt		—		140,812			—		140,812
Trading securities
Corporate debt		—		33,697			—		33,697
U.S. Treasuries		—		55,248			—		55,248
Mutual funds held in rabbi trust		—		5,868			—		5,868
Foreign currency forward position		—		231			—		231
Total	$	163,734	$	235,856		$	—	$	399,590
As of December 31, 2018
Money market funds	$	112,529	$	—		$	—	$	112,529
Securities available-for-sale
Corporate debt		—		146,966			—		146,966
Trading securities
Corporate debt		—		71,861			—		71,861
U.S. Treasuries		—		17,178			—		17,178
Mutual funds held in rabbi trust		—		4,100			—		4,100
Foreign currency forward position		—		(1,021	)		—		(1,021	)
Total	$	112,529	$	239,084		$	—	$	351,613

Summary of Foreign Currency Forward Contracts

A summary of the Company’s foreign currency forward position is as follows:

	As of
	September 30, 2019		December 31, 2018
	(In thousands)
Notional value	$	134,907	$	106,306
Fair value of notional		134,676		107,327
Fair value of the asset (liability)	$	231	$	(1,021	)

Summary of Company's Investments

The following is a summary of the Company’s investments:

	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
	(In thousands)
As of September 30, 2019
Securities available-for-sale
Corporate debt	$	140,104	$	732	$	(24	)	$	140,812
Trading securities
Corporate debt		33,676		30		(9	)		33,697
U.S. Treasuries		54,661		587		—			55,248
Mutual funds held in rabbi trust		5,173		695		—			5,868
Total trading securities		93,510		1,312		(9	)		94,813
Total investments	$	233,614	$	2,044	$	(33	)	$	235,625
As of December 31, 2018
Securities available-for-sale
Corporate debt	$	147,556	$	27	$	(617	)	$	146,966
Trading securities
Corporate debt		72,274		8		(421	)		71,861
U.S. Treasuries		16,953		225		—			17,178
Mutual funds held in rabbi trust		4,347		—		(247	)		4,100
Total trading securities		93,574		233		(668	)		93,139
Total investments	$	241,130	$	260	$	(1,285	)	$	240,105

Summary of Fair Value of Investments Based upon Contractual Maturities

The following table summarizes the fair value of the investments based upon the contractual maturities:

	As of
	September 30, 2019		December 31, 2018
	(In thousands)
Less than one year	$	116,365	$	134,255
Due in 1 - 5 years		119,260		105,850
Total	$	235,625	$	240,105

Fair Values and Unrealized Losses on Investments

The following table provides fair values and unrealized losses on investments and by the aging of the securities’ continuous unrealized loss position as of September 30, 2019 and December 31, 2018:

	Less than Twelve Months					Twelve Months or More					Total
	Estimated fair value		Gross unrealized losses			Estimated fair value		Gross unrealized losses			Estimated fair value		Gross unrealized losses
	(In thousands)
As of September 30, 2019
Corporate debt	$	21,666	$	(19	)	$	16,916	$	(14	)	$	38,582	$	(33	)
As of December 31, 2018
Corporate debt	$	80,282	$	(256	)	$	87,028	$	(782	)	$	167,310	$	(1,038	)