Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 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)
March 31, 2019
Money market funds	$	155,570	$	—		$	—	$	155,570
Securities available-for-sale
Corporate debt		—		133,051			—		133,051
Trading securities
Corporate debt		—		56,465			—		56,465
U.S. Treasuries		—		27,296			—		27,296
Mutual funds held in rabbi trust		—		5,646			—		5,646
Foreign currency forward position		—		1,096			—		1,096
Total	$	155,570	$	223,554		$	—	$	379,124
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
	March 31, 2019		December 31, 2018
	(In thousands)
Notional value	$	123,263	$	106,306
Fair value of notional		122,167		107,327
Fair value of the asset (liability)	$	1,096	$	(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 March 31, 2019
Securities available-for-sale
Corporate debt	$	133,039	$	238	$	(226	)	$	133,051
Trading securities
Corporate debt		56,626		2		(163	)		56,465
U.S. Treasuries		26,949		347		—			27,296
Mutual funds held in rabbi trust		5,281		365		—			5,646
Total trading securities		88,856		714		(163	)		89,407
Total investments	$	221,895	$	952	$	(389	)	$	222,458
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
	March 31, 2019		December 31, 2018
	(In thousands)
Less than one year	$	129,435	$	134,255
Due in 1 - 5 years		93,023		105,850
Total	$	222,458	$	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 March 31, 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 March 31, 2019
Corporate debt	$	27,031	$	(18	)	$	82,528	$	(371	)	$	109,559	$	(389	)
As of December 31, 2018
Corporate debt	$	80,282	$	(256	)	$	87,028	$	(782	)	$	167,310	$	(1,038	)