v3.4.0.3

Investments (Tables) | 3 Months Ended
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Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract] |
Components of Investments | Investments consisted of the following as of March 31, 2016:
|  | Cost Basis |  |  | Unrealized Gains |  |  | Unrealized Losses |  |  | Fair Value |
|  | (Thousands of dollars) |
Investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market mutual funds |  | $ | 17,877 |  |  | $ | — |  |  | $ | — |  |  | $ | 17,877 |
Commercial paper |  |  | 5,994 |  |  |  | 1 |  |  |  | — |  |  |  | 5,995 |
U.S. Government agencies |  |  | 27,301 |  |  |  | 7 |  |  |  | (6 | ) |  |  | 27,302 |
Corporate bonds and notes |  |  | 250,399 |  |  |  | 94 |  |  |  | (192 | ) |  |  | 250,301 |
Subtotal |  |  | 301,571 |  |  |  | 102 |  |  |  | (198 | ) |  |  | 301,475 |
Deferred compensation plan assets included in other assets |  |  | 2,334 |  |  |  | — |  |  |  | — |  |  |  | 2,334 |
Total |  | $ | 303,905 |  |  | $ | 102 |  |  | $ | (198 | ) |  | $ | 303,809 |
Investments consisted of the following as of December 31, 2015:
|  | Cost Basis |  |  | Unrealized Gains |  |  | Unrealized Losses |  |  | Fair Value |
|  | (Thousands of dollars) |
Investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market mutual funds |  | $ | 18,181 |  |  | $ | — |  |  | $ | — |  |  | $ | 18,181 |
Commercial paper |  |  | 5,986 |  |  |  | — |  |  |  | (5 | ) |  |  | 5,981 |
U.S. Government agencies |  |  | 11,499 |  |  |  | — |  |  |  | (30 | ) |  |  | 11,469 |
Corporate bonds and notes |  |  | 265,069 |  |  |  | — |  |  |  | (841 | ) |  |  | 264,228 |
Subtotal |  |  | 300,735 |  |  |  | — |  |  |  | (876 | ) |  |  | 299,859 |
Deferred compensation plan assets included in other assets |  |  | 2,294 |  |  |  | — |  |  |  | — |  |  |  | 2,294 |
Total |  | $ | 303,029 |  |  | $ | — |  |  | $ | (876 | ) |  | $ | 302,153 |
Cost and Fair Value of Debt Investments Based on Maturities | The following table presents the cost and fair value of our debt investments based on maturities as of:
|  | March 31, 2016 |  |  | December 31, 2015 |
|  | Amortized Costs |  |  | Fair Value |  |  | Amortized Costs |  |  | Fair Value |
|  | (Thousands of dollars) |
Due in one year or less |  | $ | 148,590 |  |  | $ | 148,516 |  |  | $ | 152,444 |  |  | $ | 152,212 |
Due within two years |  |  | 135,104 |  |  |  | 135,082 |  |  |  | 130,110 |  |  |  | 129,466 |
Total |  | $ | 283,694 |  |  | $ | 283,598 |  |  | $ | 282,554 |  |  | $ | 281,678 |
Average Coupon Rate Percentage and Average Days to Maturity of Debt | The following table presents the average coupon rate percentage and the average days to maturity of our debt investments as of:
|  | March 31, 2016 |  |  | December 31, 2015 |
|  | Average Coupon Rate (%) |  |  | Average Days To Maturity |  |  | Average Coupon Rate (%) |  |  | Average Days To Maturity |
Commercial paper |  |  | 0.553 |  |  |  | 63 |  |  |  | 0.553 |  |  |  | 154 |
U.S. Government agencies |  |  | 0.985 |  |  |  | 602 |  |  |  | 0.865 |  |  |  | 599 |
Corporate bonds and notes |  |  | 1.727 |  |  |  | 328 |  |  |  | 1.757 |  |  |  | 331 |
Investments in Continuous Unrealized Loss Position for Less Than Twelve Months | The following table presents the fair value and unrealized losses related to our investments that have been in a continuous unrealized loss position for less than twelve months as of:
|  | March 31, 2016 |  |  | December 31, 2015 |
|  | Fair Value |  |  | Unrealized Losses |  |  | Fair Value |  |  | Unrealized Losses |
|  | (Thousands of dollars) |
Commercial paper |  | $ | 0 |  |  | $ | 0 |  |  | $ | 5,981 |  |  | $ | (5 | )
U.S. Government agencies |  |  | 11,996 |  |  |  | (6 | ) |  |  | 8,969 |  |  |  | (30 | )
Corporate bonds and notes |  |  | 134,298 |  |  |  | (150 | ) |  |  | 232,347 |  |  |  | (793 | )
Total |  | $ | 146,294 |  |  | $ | (156 | ) |  | $ | 247,297 |  |  | $ | (828 | )
Investments in Continuous Unrealized Loss Position for More Than Twelve Months | The following table presents the fair value and unrealized losses related to our investments that have been in a continuous unrealized loss position for more than twelve months as of:
|  | March 31, 2016 |  |  | December 31, 2015 |
|  | Fair Value |  |  | Unrealized Losses |  |  | Fair Value |  |  | Unrealized Losses |
|  | (Thousands of dollars) |
Corporate bonds and notes |  | $ | 47,783 |  |  | $ | (42 | ) |  | $ | 28,866 |  |  | $ | (48 | )
Total |  | $ | 47,783 |  |  | $ | (42 | ) |  | $ | 28,866 |  |  | $ | (48 | )

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