OTHER ASSETS

12 Months Ended

Dec. 31, 2023

NOTE 10. OTHER ASSETS

Included in other assets were the following:


	December 31,
	2023		2022
Other Assets	($ in millions)
Supply contracts	$	1,061.8	$	1,048.0
Other	56.7		54.5
Other assets	$	1,118.5	$	1,102.5

For the year ended December 31, 2023 and 2022, payments of $64.5 million and $37.7 million, respectively, were made under other long-term supply contracts for energy modernization projects on the U.S. Gulf Coast. The weighted-average useful life of long-term supply contracts at December 31, 2023, was 20 years. For the years ended December 31, 2023, 2022 and 2021, amortization expense of $71.2 million, $70.4 million and $69.4 million, respectively, was recognized within cost of goods sold related to our supply contracts and is reflected in depreciation and amortization on the consolidated statements of cash flows.

We estimate that amortization expense will be approximately $71.4 million in 2024, 2025 and 2026, $69.8 million in 2027 and $66.5 million in 2028 related to our long-term supply contracts. The long-term supply contracts are monitored for impairment each reporting period.