Available for Sale Securities

6 Months Ended

Jun. 30, 2017

Investments Debt And Equity Securities [Abstract]

Available for Sale Securities

4. Available for sale securities

Available for sale securities at June 30, 2017 and December 31, 2016 consist of the following:

			Gross		Gross
			Unrealized		Unrealized
	Amortized Cost		Gains		Losses			Fair Value
	(in thousands)
June 30, 2017
Cash and cash equivalents	$	125,390	$	—	$	—		$	125,390
Available for sale securities:
Certificates of deposit	$	14,855	—		—			$	14,855
U.S. Government debt securities		128,413	—			(187	)		128,226
Corporate debt securities		52,810				(66	)		52,744
Total available for sale securities	$	196,078	$	—	$	(253	)	$	195,825
Total cash, cash equivalents, and available for sale securities	$	321,468	$	—	$	(253	)	$	321,215

			Gross		Gross
			Unrealized		Unrealized
	Amortized Cost		Gains		Losses			Fair Value
	(in thousands)
December 31, 2016
Cash and cash equivalents	$	187,335	$	—	$	—		$	187,335
Available for sale securities:
Certificates of deposit	$	12,698	—			—		$	12,698
U.S. Government debt securities		50,952	—			(32	)		50,920
Corporate debt securities		9,398	—			(8	)		9,390
Total available for sale securities	$	73,048	$	—	$	(40	)	$	73,008
Total cash, cash equivalents, and available for sale securities	$	260,383	$	—	$	(40	)	$	260,343

The estimated fair value of the Company’s available for sale securities balance at June 30, 2017, by contractual maturity, is as follows:

Due in one year or less	$	191,182
Due after one year		4,643
Total available for sale securities	$	195,825