Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2016

Investments Debt And Equity Securities [Abstract]

Summary of Available for Sale Securities Held

The following table summarizes the available-for-sale securities held at December 31, 2016 and 2015 (in thousands):

Description	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
December 31, 2016
U.S. government agency securities and treasuries	$	600,001	$	34	$	(575	)	$	599,460
Certificates of deposit		6,480		6		(3	)		6,483
Total	$	606,481	$	40	$	(578	)	$	605,943
December 31, 2015
U.S. government agency securities and treasuries	$	689,425	$	22	$	(2,300	)	$	687,147
Certificates of deposit		14,360		—		(13	)		14,347
Total	$	703,785	$	22	$	(2,313	)	$	701,494

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details