INVESTMENTS

Long-term investments held by us are debt securities designated as available for sale and are reported at fair market value using the specific identification method. The following table summarizes unrealized gains and losses related to these investments as of December 31, 2018 and December 31, 2017:



Dollar amounts in millions	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2018	$	0.4	$	5.7	$	—	$	6.1

December 31, 2017	$	0.4	$	5.6	$	—	$	6.0

As of December 31, 2018, we had $6.1 million ($19.3 million, par value) invested in auction rate securities (ARS). The ARS held by us are securities with long-term nominal maturities for which the interest rates may be reset through a Dutch auction each month. Our investments in ARS represent interests in collateralized debt obligations supported by pools of residential and commercial mortgages and other securities. The contractual maturities of these debt securities classified as available for sale at December 31, 2018 exceed one year.

During 2018, we received a return of principal on our ARS of $0.4 million. We recorded a gain on securities of $0.4 million, which represents a recovery of losses previously recorded as "Other-than-temporary impairment."

There were no purchases of short-term and long-term investments for the years ended December 31, 2018 and 2017. During 2018 and 2017, we did not own any short-term investments.