Investment Securities (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Investment securities, available-for-sale consisted of the following (in thousands):



	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value (net carrying amount)
As of December 31, 2017
Domestic and foreign corporate bonds	$	328,747	$	6	$	(1,298	)	$	327,455

As of December 31, 2016
Domestic and foreign corporate bonds	$	245,425	$	19	$	(720	)	$	244,724
Commercial paper	56,764		5		(33		)	56,736
Total	$	302,189	$	24	$	(753	)	$	301,460

Investments by Contractual Maturity

The fair value of these investment securities as of December 31, 2017, by contractual maturity, are as follows (in thousands):



	Fair value
Available-for-sale securities
Due in one year or less	$	166,773
Due after one year through two years	118,280
Due after two years through three years	42,402
	$	327,455

- 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