v3.19.3.a.u2

ACCRUED LIABILITIES | 12 Months Ended
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Dec. 31, 2019
Accrued Liabilities, Current [Abstract] |
ACCRUED LIABILITIES | ACCRUED LIABILITIES Accrued liabilities consisted of the following:
| December 31,
| 2019 |  | 2018
| (Thousands of Dollars)
Employee wages and benefit costs | $ | 36,704 |  |  | $ | 29,518 |
Revenue contract liabilities | 21,083 |  |  | 21,579 |
Interest rate swaps | 19,169 |  |  | — |
Operating lease liabilities | 10,416 |  |  | — |
Other | 16,913 |  |  | 23,321 |
Accrued liabilities | $ | 104,285 |  |  | $ | 74,418 |

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