GOODWILL AND INTANGIBLE ASSETS (Notes)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill - The following table sets forth our goodwill, by segment, for the periods indicated:



	December 31, 2019		December 31, 2018
	(Thousands of dollars)
Natural Gas Gathering and Processing	$	153,404	$	153,404
Natural Gas Liquids	371,217		371,217
Natural Gas Pipelines	156,375		156,479
Total goodwill	$	680,996	$	681,100

Intangible Assets - Our intangible assets relate primarily to contracts acquired through acquisitions in our Natural Gas Gathering and Processing and Natural Gas Liquids segments, which are being amortized over periods of 15 to 40 years. Amortization expense for intangible assets was $11.9 million in 2019, 2018 and 2017, and the aggregate amortization expense for each of the next five years is estimated to be $11.9 million. The following table reflects the gross carrying amount and accumulated amortization of intangible assets for the periods presented:



	December 31, 2019			December 31, 2018
	(Thousands of dollars)
Gross intangible assets	$	414,345		$	411,650
Accumulated amortization	(137,508		)	(125,608		)
Net intangible assets	$	276,837		$	286,042