Investments (Tables)
|
12 Months Ended |
Dec. 31, 2015 |
|---|
| Investments, Debt and Equity Securities [Abstract] |
|
| Components of Investments |
Investments consisted of the following as of December 31,
2015:
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Unrealized |
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Unrealized |
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Fair |
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| |
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Cost Basis |
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Gains |
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Losses |
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Value |
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| |
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(Thousands of
dollars) |
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Investments:
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Money market mutual funds
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|
$ |
18,181 |
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|
$ |
— |
|
|
$ |
— |
|
|
$ |
18,181 |
|
|
Commercial paper
|
|
|
5,986 |
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|
|
— |
|
|
|
(5 |
) |
|
|
5,981 |
|
|
U.S. government agencies
|
|
|
11,499 |
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|
|
— |
|
|
|
(30 |
) |
|
|
11,469 |
|
|
Corporate bonds and notes
|
|
|
265,069 |
|
|
|
— |
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|
|
(841 |
) |
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|
264,228 |
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Subtotal
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|
300,735 |
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|
— |
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(876 |
) |
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|
299,859 |
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Deferred compensation plan assets included in other assets
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|
2,294 |
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|
|
— |
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|
|
— |
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|
|
2,294 |
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|
|
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|
|
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|
|
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Total
|
|
$ |
303,029 |
|
|
$ |
— |
|
|
$ |
(876 |
) |
|
$ |
302,153 |
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|
Investments consisted of the following as of December 31,
2014:
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| |
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Unrealized |
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Unrealized |
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Fair |
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| |
|
Cost Basis |
|
|
Gains |
|
|
Losses |
|
|
Value |
|
| |
|
(Thousands of
dollars) |
|
|
Investments:
|
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|
|
|
|
|
|
|
|
|
|
|
|
|
|
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Money market mutual funds
|
|
$ |
68,612 |
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|
$ |
— |
|
|
$ |
— |
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|
$ |
68,612 |
|
|
Municipal bonds and notes
|
|
|
1,500 |
|
|
|
2 |
|
|
|
— |
|
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|
1,502 |
|
|
Corporate bonds and notes
|
|
|
130,864 |
|
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|
19 |
|
|
|
(268 |
) |
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|
130,615 |
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Subtotal
|
|
|
200,976 |
|
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|
21 |
|
|
|
(268 |
) |
|
|
200,729 |
|
|
|
|
|
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|
Deferred compensation plan assets included in other assets
|
|
|
2,386 |
|
|
|
— |
|
|
|
— |
|
|
|
2,386 |
|
|
|
|
|
|
|
|
|
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|
|
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|
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Total
|
|
$ |
203,362 |
|
|
$ |
21 |
|
|
$ |
(268 |
) |
|
$ |
203,115 |
|
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| 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 December 31,
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2015 |
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|
2014 |
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Amortized |
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Fair |
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Amortized |
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Fair |
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| |
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Costs |
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Value |
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|
Costs |
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Value |
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|
(Thousands of
dollars) |
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|
Due in one year or less
|
|
$ |
152,444 |
|
|
$ |
152,212 |
|
|
$ |
70,180 |
|
|
$ |
70,169 |
|
|
Due within two years
|
|
|
130,110 |
|
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|
129,466 |
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|
|
62,184 |
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|
61,948 |
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Total
|
|
$ |
282,554 |
|
|
$ |
281,678 |
|
|
$ |
132,364 |
|
|
$ |
132,117 |
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| 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
December 31,
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2015 |
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|
2014 |
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Average |
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|
Average |
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|
Average |
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|
Average |
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Coupon |
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Days To |
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Coupon |
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|
Days To |
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Rate (%) |
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Maturity |
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|
Rate (%) |
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|
Maturity |
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|
Commercial paper
|
|
|
0.553 |
|
|
|
154 |
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|
n/a |
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|
n/a |
|
|
U.S. government agencies
|
|
|
0.865 |
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|
599 |
|
|
|
n/a |
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|
|
n/a |
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|
Municipal bonds and notes
|
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|
n/a |
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|
|
n/a |
|
|
|
0.528 |
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|
134 |
|
|
Corporate bonds and notes
|
|
|
1.757 |
|
|
|
331 |
|
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|
1.828 |
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|
|
348 |
|
|
| 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
December 31,
|
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| |
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2015 |
|
|
2014 |
|
| |
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Unrealized |
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|
Unrealized |
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| |
|
Fair Value |
|
|
Losses |
|
|
Fair Value |
|
|
Losses |
|
| |
|
(Thousands of
dollars) |
|
|
Commercial paper
|
|
$ |
5,981 |
|
|
$ |
(5 |
) |
|
$ |
— |
|
|
$ |
— |
|
|
U.S. government agencies
|
|
|
8,969 |
|
|
|
(30 |
) |
|
|
— |
|
|
|
— |
|
|
Corporate bonds and notes
|
|
|
232,347 |
|
|
|
(793 |
) |
|
|
100,071 |
|
|
|
(268 |
) |
|
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|
|
|
|
|
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Total
|
|
$ |
247,297 |
|
|
$ |
(828 |
) |
|
$ |
100,071 |
|
|
$ |
(268 |
) |
|
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|
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| Investments in Continuous Unrealized Loss Position For Twelve Months Or More |
The following table presents the fair value and unrealized losses
related to our investments that have been in a continuous
unrealized loss position for twelve months or more as of
December 31,
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
2015 |
|
|
2014 |
|
| |
|
|
|
|
Unrealized |
|
|
|
|
|
Unrealized |
|
| |
|
Fair Value |
|
|
Losses |
|
|
Fair Value |
|
|
Losses |
|
| |
|
(Thousands of
dollars) |
|
|
Corporate bonds and notes
|
|
$ |
28,866 |
|
|
$ |
(48 |
) |
|
$ |
— |
|
|
$ |
— |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Total
|
|
$ |
28,866 |
|
|
$ |
(48 |
) |
|
$ |
— |
|
|
$ |
— |
|
|
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