INVESTMENTS

The Company determines the appropriate classification of debt investments at the time of purchase and re-evaluates such designation as of each balance sheet date. The Company considers all of its investments to be available-for-sale. The Company's investments consist of long-term variable rate debt instruments with an auction reset feature, referred to as ARS. Investments are carried at fair value.

Scheduled maturities of investments classified as available-for-sale as of September 30, 2018 are as follows (in thousands):



Maturity	Fair Value
Due:
October 1, 2018 — September 30, 2019	$	—
October 1, 2019 — September 30, 2023	—
October 1, 2023 — September 30, 2028	—
After September 30, 2028	10,070
Available-for-sale investments	$	10,070

The Company had no realized gains or losses on its investments for each of the three and nine months ended September 30, 2018 and 2017, respectively. Realized gains and losses from the sale of available-for-sale securities are determined on a specific-identification basis.

Changes in unrealized holding gains and losses, net of the related tax effect, on available-for-sale securities are excluded from earnings and are reported as a separate component of accumulated other comprehensive loss in stockholders’ equity until realized. A decline in market value of any available-for-sale security below cost that is deemed to be other-than-temporary results in a reduction in carrying amount to fair value. The impairment is charged to earnings and a new cost basis for the security is established. Dividend and interest income are recognized when earned.

As of September 30, 2018, the amortized cost basis and fair value of investments classified as available-for-sale were as follows (in thousands):



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Auction rate securities	$	10,800	$	—	$	(730	)	$	10,070
Available-for-sale investments	$	10,800	$	—	$	(730	)	$	10,070

As of December 31, 2017, the amortized cost basis and fair value of investments classified as available-for-sale were as follows (in thousands):



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Auction rate securities	$	10,800	$	—	$	(730	)	$	10,070
Available-for-sale investments	$	10,800	$	—	$	(730	)	$	10,070

The unrealized losses on the Company’s investments as of September 30, 2018 and December 31, 2017 were generated primarily from changes in interest rates and ARS that failed to settle at auction, due to adverse conditions in the global credit markets. The losses are considered temporary, as the contractual terms of these investments do not permit the issuer to settle the security at a price less than the amortized cost of the investment. Because the Company does not intend to sell these instruments and it is not more likely than not that the Company will be required to sell these instruments prior to anticipated recovery, which may be at maturity, the Company does not consider these investments to be other-than-temporarily impaired as of September 30, 2018 and December 31, 2017. See Note 6 for further discussion of the fair value of the Company’s financial assets.

The components of the Company’s investments in an unrealized loss position for twelve months or longer were as follows (in thousands):



	September 30, 2018					December 31, 2017
	Aggregate Fair Value		Gross Unrealized Losses			Aggregate Fair Value		Gross Unrealized Losses
Auction rate securities	$	10,070	$	(730	)	$	10,070	$	(730	)
Investments in an unrealized loss position	$	10,070	$	(730	)	$	10,070	$	(730	)

The Company did not have any investments in an unrealized loss position for less than twelve months as of September 30, 2018 and December 31, 2017.