Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2019

Investments Debt And Equity Securities [Abstract]

Summary of Company Marketable Securities

The following tables present a summary of the Company’s marketable securities, which consist of available-for-sale debt securities and equity securities (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
June 30, 2019
U.S. government and federal agency securities	$	102,825	$	388	$	—		$	103,213
Certificates of deposit		8,748		67		—			8,815
Corporate bonds		249,377		1,070		(3	)		250,444
Equity securities		420		31,656		—			32,076
	$	361,370	$	33,181	$	(3	)	$	394,548

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
December 31, 2018
U.S. government and federal agency securities	$	103,410	$	93	$	(37	)	$	103,466
Certificates of deposit		8,992		—		—			8,992
Corporate bonds		282,902		36		(377	)		282,561
	$	395,304	$	129	$	(414	)	$	395,019

Summary of Fair Values and Unrealized Losses of Marketable Securities Held by the Company in an Unrealized Loss Position for Less Than 12 months and 12 Months or Greater

The following tables present the fair values and unrealized losses of available-for-sale debt securities held by the Company in an unrealized loss position for less than 12 months and 12 months or greater (in thousands):

	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
June 30, 2019
Corporate bonds	$	19,176	$	(3	)	$	—	$	—	$	19,176	$	(3	)
	$	19,176	$	(3	)	$	—	$	—	$	19,176	$	(3	)

	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
December 31, 2018
U.S. government and federal    agency securities	$	53,124	$	(37	)	$	—	$	—		$	53,124	$	(37	)
Corporate bonds		245,283		(354	)		12,424		(23	)		257,707		(377	)
	$	298,407	$	(391	)	$	12,424	$	(23	)	$	310,831	$	(414	)