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Investments (Tables) | 3 Months Ended
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Mar. 31, 2012
Investments |
Summary of the amortized cost and estimated fair value of short-term investments for both available-for-sale and trading securities |
|  | 2012 |  | 2011 |
|  | Amortized |  | Fair |  | Amortized |  | Fair |
(Thousands of dollars) |  | Cost |  | Value |  | Cost |  | Value |
Corporate bonds |  | $ | 132,726 |  | $ | 133,989 |  | $ | 88,589 |  | $ | 89,146 |
Money market funds |  | 69,867 |  | 69,867 |  | 139,420 |  | 139,420 |
U.S. Treasury securities |  | 36,110 |  | 36,095 |  | 4,848 |  | 4,905 |
Collateralized mortgage obligations |  | 22,677 |  | 22,720 |  | 14,915 |  | 15,011 |
Fixed rate municipal notes and bonds |  | 21,275 |  | 21,335 |  | 17,718 |  | 17,788 |
U.S. Government agency securities |  | 18,534 |  | 18,603 |  | 9,720 |  | 9,757 |
Emerging markets debt mutual fund |  | 17,693 |  | 17,687 |  | 17,693 |  | 16,399 |
Asset backed debt securities |  | 10,530 |  | 10,536 |  | 3,533 |  | 3,533 |
Other |  | 1,480 |  | 1,483 |  | 1,480 |  | 1,484 |
Total available-for-sale short-term investments |  | 330,892 |  | 332,315 |  | 297,916 |  | 297,443 |
High yield trading debt securities |  | 21,217 |  | 22,349 |  | 20,155 |  | 20,750 |
Emerging markets trading debt mutual funds |  | 2,651 |  | 2,686 |  | 2,620 |  | 2,487 |
Emerging markets trading debt securities |  | 2,099 |  | 2,246 |  | 2,444 |  | 2,355 |
Other trading debt securities |  | 217 |  | 238 |  | 218 |  | 221 |
Total available-for-sale and trading short-term investments |  | $ | 357,076 |  | $ | 359,834 |  | $ | 323,353 |  | $ | 323,256
Summary of estimated fair value of fixed rate securities designated as available-for-sale, classified by the contractual maturity date of the security |
(Thousands of dollars) |  | 2012 |
Due within one year |  | $ | 53,083 |
Due after one year through three years |  | 90,771 |
Due after three years |  | 66,844 |
Total fixed rate securities |  | $ | 210,698

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- Definition A table of investments, shown as a text block. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 + Details
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