| Summary of Valuation of Investments and Financial Instruments Pricing Levels |
The following table summarizes the valuation of our investments and
financial instruments by the above pricing levels as of the
valuation dates listed:
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|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
March 31, 2017 |
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| |
|
Total |
|
|
(Level 1) |
|
|
(Level 2) |
|
| |
|
|
|
|
(Thousands of dollars) |
|
|
Investments:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Money market mutual funds
|
|
$ |
10,597 |
|
|
$ |
10,597 |
|
|
$ |
— |
|
|
Commercial paper
|
|
|
27,909 |
|
|
|
— |
|
|
|
27,909 |
|
|
U.S. Government agencies
|
|
|
15,285 |
|
|
|
— |
|
|
|
15,285 |
|
|
Corporate bonds and notes
|
|
|
236,050 |
|
|
|
— |
|
|
|
236,050 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
289,841 |
|
|
|
10,597 |
|
|
|
279,244 |
|
|
|
|
|
|
Deferred compensation plan assets
|
|
|
2,500 |
|
|
|
2,500 |
|
|
|
— |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Total
|
|
$ |
292,341 |
|
|
$ |
13,097 |
|
|
$ |
279,244 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
December 31, 2016 |
|
| |
|
Total |
|
|
(Level 1) |
|
|
(Level 2) |
|
| |
|
|
|
|
(Thousands of
dollars) |
|
|
Investments:
|
|
|
|
|
|
|
|
|
|
Money market mutual funds
|
|
$ |
18,118 |
|
|
$ |
18,118 |
|
|
$ |
— |
|
|
Commercial paper
|
|
|
27,867 |
|
|
|
— |
|
|
|
27,867 |
|
|
U.S. government agencies
|
|
|
13,263 |
|
|
|
— |
|
|
|
13,263 |
|
|
Corporate bonds and notes
|
|
|
243,582 |
|
|
|
— |
|
|
|
243,582 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
302,830 |
|
|
|
18,118 |
|
|
|
284,712 |
|
|
|
|
|
|
Deferred compensation plan assets
|
|
|
2,394 |
|
|
|
2,394 |
|
|
|
— |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Total
|
|
$ |
305,224 |
|
|
$ |
20,512 |
|
|
$ |
284,712 |
|
|
|
|
|
|
|
|
|
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|