| Payments Due by Period | ||||||||
| 2015- | 2019 and | |||||||
| 2014 | 2018 | Beyond | Total | |||||
| (millions of dollars) | ||||||||
| Unconditional purchase obligations (1) | 144 | 629 | 463 | 1,236 | ||||
(1) Undiscounted obligations of $1,236 million mainly pertain to pipeline throughput agreements and include $457 million of obligations to equity companies. The present value of these commitments, which excludes imputed interest of $267 million, totaled $969 million.