v3.5.0.2

Investments (Tables) | 9 Months Ended
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Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract] |
Components of Investments | Investments consisted of the following as of September 30, 2016:
|  | Cost Basis |  |  | Unrealized Gains |  |  | Unrealized Losses |  |  | Fair Value |
|  | (Thousands of dollars) |
Investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market mutual funds |  | $ | 17,608 |  |  | $ | — |  |  | $ | — |  |  | $ | 17,608 |
Commercial paper |  |  | 32,820 |  |  |  | — |  |  |  | (75 | ) |  |  | 32,745 |
U.S. Government agencies |  |  | 16,296 |  |  |  | 5 |  |  |  | (3 | ) |  |  | 16,298 |
Corporate bonds and notes |  |  | 236,215 |  |  |  | 33 |  |  |  | (355 | ) |  |  | 235,893 |
Subtotal |  |  | 302,939 |  |  |  | 38 |  |  |  | (433 | ) |  |  | 302,544 |
Deferred compensation plan assets included in other assets |  |  | 2,392 |  |  |  | — |  |  |  | — |  |  |  | 2,392 |
Total |  | $ | 305,331 |  |  | $ | 38 |  |  | $ | (433 | ) |  | $ | 304,936 |
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:
|  | September 30, 2016 |  |  | December 31, 2015 |
|  | Amortized |  |  | Fair |  |  | Amortized |  |  | Fair |
|  | Costs |  |  | Value |  |  | Costs |  |  | Value |
|  | (Thousands of dollars) |
Due in one year or less |  | $ | 171,336 |  |  | $ | 171,152 |  |  | $ | 152,444 |  |  | $ | 152,212 |
Due within two years |  |  | 113,995 |  |  |  | 113,784 |  |  |  | 130,110 |  |  |  | 129,466 |
Total |  | $ | 285,331 |  |  | $ | 284,936 |  |  | $ | 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:
|  | September 30, 2016 |  |  | December 31, 2015 |
|  | Average |  |  | Average |  |  | Average |  |  | Average |
|  | Coupon |  |  | Days To |  |  | Coupon |  |  | Days To |
|  | Rate (%) |  |  | Maturity |  |  | Rate (%) |  |  | Maturity |
Commercial paper |  |  | 0.978 |  |  |  | 253 |  |  |  | 0.553 |  |  |  | 154 |
U.S. Government agencies |  |  | 0.979 |  |  |  | 512 |  |  |  | 0.865 |  |  |  | 599 |
Corporate bonds and notes |  |  | 1.643 |  |  |  | 330 |  |  |  | 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:
|  | September 30, 2016 |  |  | December 31, 2015 |
|  |  |  |  | Unrealized |  |  |  |  |  | Unrealized |
|  | Fair Value |  |  | Losses |  |  | Fair Value |  |  | Losses |
|  | (Thousands of dollars) |
Commercial paper |  | $ | 31,753 |  |  | $ | (75 | ) |  | $ | 5,981 |  |  | $ | (5 | )
U.S. Government agencies |  |  | 7,001 |  |  |  | (2 | ) |  |  | 8,969 |  |  |  | (30 | )
Corporate bonds and notes |  |  | 169,833 |  |  |  | (320 | ) |  |  | 232,347 |  |  |  | (793 | )
Total |  | $ | 208,587 |  |  | $ | (397 | ) |  | $ | 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:
|  | September 30, 2016 |  |  | December 31, 2015 |
|  |  |  |  | Unrealized |  |  |  |  |  | Unrealized |
|  | Fair Value |  |  | Losses |  |  | Fair Value |  |  | Losses |
|  | (Thousands of dollars) |
Corporate bonds and notes |  | $ | 34,002 |  |  | $ | (36 | ) |  | $ | 28,866 |  |  | $ | (48 | )
Total |  | $ | 34,002 |  |  | $ | (36 | ) |  | $ | 28,866 |  |  | $ | (48 | )

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