Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

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 June 30, 2017
Money market funds	$	11,087	$	—		$	—	$	11,087
Securities available-for-sale
Corporate debt		—		160,080			—		160,080
Trading securities
Corporate debt		—		74,332			—		74,332
Mutual funds held in rabbi trust		—		2,949			—		2,949
Foreign currency forward position		—		(2,346	)		—		(2,346	)
Total	$	11,087	$	235,015		$	—	$	246,102
As of December 31, 2016
Money market funds	$	58,573	$	—		$	—	$	58,573
Securities available-for-sale
Corporate debt		—		118,870			—		118,870
Trading securities
Corporate debt		—		74,207			—		74,207
Mutual funds held in rabbi trust		—		1,327			—		1,327
Foreign currency forward position		—		(266	)		—		(266	)
Total	$	58,573	$	194,138		$	—	$	252,711

Summary of Foreign Currency Forward Contracts

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

	As of
	June 30, 2017			December 31, 2016
	(In thousands)
Notional value	$	77,079		$	66,972
Fair value of notional		79,425			67,238
Fair value of the liability	$	(2,346	)	$	(266	)

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 June 30, 2017
Securities available-for-sale
Corporate debt	$	160,299	$	11	$	(230	)	$	160,080
Trading securities
Corporate debt		74,424		78		(170	)		74,332
Mutual funds held in rabbi trust		2,729		220		—			2,949
Total trading securities		77,153		298		(170	)		77,281
Total investments	$	237,452	$	309	$	(400	)	$	237,361
As of December 31, 2016
Securities available-for-sale
Corporate debt	$	119,073	$	13	$	(216	)	$	118,870
Trading securities
Corporate debt		74,394		47		(234	)		74,207
Mutual funds held in rabbi trust		1,212		115		—			1,327
Total trading securities		75,606		162		(234	)		75,534
Total investments	$	194,679	$	175	$	(450	)	$	194,404

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
	June 30, 2017		December 31, 2016
	(In thousands)
Less than one year	$	138,491	$	117,904
Due in 1 - 5 years		98,870		76,500
Total	$	237,361	$	194,404

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 June 30, 2017 and December 31, 2016:

	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 June 30, 2017
Corporate debt	$	177,728	$	(400	)	$	—	$	—		$	177,728	$	(400	)
As of December 31, 2016
Corporate debt	$	136,667	$	(449	)	$	2,000	$	(1	)	$	138,667	$	(450	)