Investments (Tables)
|
6 Months Ended |
Jun. 30, 2017 |
|---|
| Investments, Debt and Equity Securities [Abstract] |
|
| Components of Investments |
Investments consisted of the following as of June 30, 2017: | | | | | | | | | | | | | | | | | | | | Cost Basis | | Unrealized
Gains | | Unrealized
Losses | | Fair
Value | | | (Thousands of dollars) | Investments: | | | | | | | | | Money market mutual funds | | $ | 18,079 |
| | $ | — |
| | $ | — |
| | $ | 18,079 |
| Commercial paper | | 17,008 |
| | — |
| | (10 | ) | | 16,998 |
| U.S. Government agencies | | 15,301 |
| | — |
| | (19 | ) | | 15,282 |
| Corporate bonds and notes | | 199,772 |
| | 1 |
| | (318 | ) | | 199,455 |
| Subtotal | | 250,160 |
| | 1 |
| | (347 | ) | | 249,814 |
| Deferred compensation plan assets included in other assets | | 2,562 |
| | — |
| | — |
| | 2,562 |
| Total | | $ | 252,722 |
| | $ | 1 |
| | $ | (347 | ) | | $ | 252,376 |
|
Investments consisted of the following as of December 31, 2016: | | | | | | | | | | | | | | | | | | | | Cost Basis | | Unrealized Gains | | Unrealized Losses | | Fair Value | | | (Thousands of dollars) | Investments: | | | | | | | | | Money market mutual funds | | $ | 18,118 |
| | $ | — |
| | $ | — |
| | $ | 18,118 |
| Commercial paper | | 27,906 |
| | — |
| | (39 | ) | | 27,867 |
| U.S. government agencies | | 13,295 |
| | — |
| | (32 | ) | | 13,263 |
| Corporate bonds and notes | | 244,202 |
| | 2 |
| | (622 | ) | | 243,582 |
| Subtotal | | 303,521 |
| | 2 |
| | (693 | ) | | 302,830 |
| Deferred compensation plan assets included in other assets | | 2,394 |
| | — |
| | — |
| | 2,394 |
| Total | | $ | 305,915 |
| | $ | 2 |
| | $ | (693 | ) | | $ | 305,224 |
|
|
| 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: | | | | | | | | | | | | | | | | | | | | June 30, 2017 | | December 31, 2016 | | | Amortized
Costs | | Fair
Value | | Amortized
Costs | | Fair
Value | | | (Thousands of dollars) | Due in one year or less | | $ | 175,910 |
| | $ | 175,682 |
| | $ | 184,587 |
| | $ | 184,334 |
| Due within two years | | 56,171 |
| | 56,053 |
| | 100,816 |
| | 100,378 |
| Total | | $ | 232,081 |
| | $ | 231,735 |
| | $ | 285,403 |
| | $ | 284,712 |
|
|
| 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: | | | | | | | | | | | | | | June 30, 2017 | | December 31, 2016 | | | Average
Coupon
Rate (%) | | Average
Days To
Maturity | | Average
Coupon
Rate (%) | | Average
Days To
Maturity | Commercial paper | | 0.985 |
| | 83 | | 1.001 |
| | 184 | U.S. Government agencies | | 1.056 |
| | 264 | | 0.970 |
| | 400 | Corporate bonds and notes | | 1.720 |
| | 246 | | 1.745 |
| | 318 |
|
| 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: | | | | | | | | | | | | | | | | | | | | June 30, 2017 | | December 31, 2016 | | | Fair Value | | Unrealized
Losses | | Fair Value | | Unrealized
Losses | | | (Thousands of dollars) | Commercial paper | | $ | 16,998 |
| | $ | (10 | ) | | $ | 27,867 |
| | $ | (39 | ) | U.S. Government agencies | | 13,287 |
| | (15 | ) | | 13,263 |
| | (32 | ) | Corporate bonds and notes | | 172,179 |
| | (286 | ) | | 210,836 |
| | (602 | ) | Total | | $ | 202,464 |
| | $ | (311 | ) | | $ | 251,966 |
| | $ | (673 | ) |
|
| 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: | | | | | | | | | | | | | | | | | | | | June 30, 2017 | | December 31, 2016 | | | Fair Value | | Unrealized
Losses | | Fair Value | | Unrealized
Losses | | | (Thousands of dollars) | U.S. Government agencies | | $ | 1,996 |
| | $ | (4 | ) | | $ | — |
| | $ | — |
| Corporate bonds and notes | | 19,064 |
| | (32 | ) | | 24,196 |
| | (20 | ) | Total | | $ | 21,060 |
| | $ | (36 | ) | | $ | 24,196 |
| | $ | (20 | ) |
|