INVESTMENTS

We classify all of our short-term investments as available-for-sale. We carry these at fair value and report unrealized gains and losses, net of taxes, in Accumulated other comprehensive loss, which is a separate component of shareholders’ equity in our Condensed Consolidated Balance Sheets. These unrealized gains and losses are also reflected in our Condensed Consolidated Statements of Comprehensive Income and Condensed Consolidated Statements of Shareholders’ Equity. We determine cost, gains, and losses using the specific identification method.

Investments consisted of the following as of March 31, 2019:



	Cost Basis		Unrealized Gains		Unrealized Losses		Fair Value
	(Thousands of dollars)
Investments:
Money market mutual funds	$	85,412	$	—	$	—	$	85,412
Deferred compensation plan assets included in other assets	856		—		—		856
Total	$	86,268	$	—	$	—	$	86,268

Investments consisted of the following as of December 31, 2018:



	Cost Basis		Unrealized Gains		Unrealized Losses		Fair Value
	(Thousands of dollars)
Investments:
Money market mutual funds	$	26,308	$	—	$	—	$	26,308
Deferred compensation plan assets included in other assets	772		—		—		772
Total	$	27,080	$	—	$	—	$	27,080

At March 31, 2019 and December 31, 2018, we classified $19.8 million of our aggregate investments as long-term investments and recorded them in our Condensed Consolidated Balance Sheets as restricted cash and investments, as they are securing outstanding letters of credit with maturities beyond one year.