Fair Value Measurements

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. FAIR VALUE MEASUREMENTS

Accounting standards require that assets and liabilities carried at fair value will be classified and disclosed in one of the following three categories:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market based inputs or unobservable inputs that are corroborated by market data.

Level 3: Unobservable inputs that are not corroborated by market data.

The following table summarizes the valuation of our investments and financial instruments by the above pricing levels as of the valuation dates listed:

			June 30, 2015
	Total		(Level 1)		(Level 2)
			(Thousands of dollars)
Investments:
Money market mutual funds	$	35,407	$	35,407	$	—
U.S. Government agencies		11,507		—		11,507
Corporate bonds and notes		185,493		—		185,493
		232,407		35,407		197,000
Deferred compensation plan assets		2,478		2,478		—
Total	$	234,885	$	37,885	$	197,000
			December 31, 2014
	Total		(Level 1)		(Level 2)
			(Thousands of dollars)
Investments:
Money market mutual funds	$	68,612	$	68,612	$	—
Municipal bonds and notes		1,502		—		1,502
Corporate bonds and notes		130,615		—		130,615
		200,729		68,612		132,117
Deferred compensation plan assets		2,386		2,386		—
Total	$	203,115	$	70,998	$	132,117

We hold our short-term investments in an investment fund consisting of high quality money market instruments of governmental and private issuers, which is classified as a short-term investment. Level 1 inputs are quoted prices (unadjusted) for identical assets or liabilities in active markets. These items are traded with sufficient frequency and volume to provide pricing on an ongoing basis. The fair values of the shares of these funds are based on observable market prices, and therefore, have been categorized in Level 1 in the fair value hierarchy. Level 2 inputs reflect quoted prices for identical assets or liabilities that are not actively traded. These items may not be traded daily; examples include corporate bonds and U.S. government agencies debt. There have been no reclassifications of assets between Level 1 and Level 2 investments during the periods covered by the financial statements included in this report. We hold no Level 3 investments. Investments included in other assets, which relate to our liability under the Officers’ Deferred Compensation Plan, consist mainly of multiple investment funds that are highly liquid and diversified.

Cash, accounts receivable, accounts payable and accrued liabilities, and our revolving credit facility debt all had fair values approximating their carrying amounts at June 30, 2015 and December 31, 2014. Our determination of the estimated fair value of our Senior Notes and our revolving credit facility debt is derived using Level 2 inputs, including quoted market indications of similar publicly-traded debt. The fair value of our Senior Notes, based on quoted market prices, was $465.0 million and $425.6 million at June 30, 2015 and December 31, 2014, respectively.