Intangible Assets, Net (Notes)

6 Months Ended

Jun. 30, 2017

Finite-Lived Intangible Assets, Net [Abstract]

Intangible Assets Disclosure [Text Block]

8. Intangible Assets, Net

A summary of intangible assets, net, is presented in the table below:

	June 30, 2017							December 31, 2016							Weighted-Average Amortization Period (Years)
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
	(In thousands)
Customer relationships	$	7,172	$	(4,499	)	$	2,673	$	7,172	$	(4,234	)	$	2,938	5.0
Pipeline rights-of-way	6,564		(3,133		)	3,431		6,527		(2,950		)	3,577		6.0
Intangible assets, net	$	13,736	$	(7,632	)	$	6,104	$	13,699	$	(7,184	)	$	6,515

Intangible asset amortization expense was $0.3 million and $0.6 million for the three and six months ended June 30, 2017 and June 30, 2016, respectively, based upon estimates of useful lives ranging from 1 to 35 years.

Estimated amortization expense for the indicated periods is as follows (in thousands):

Remainder of 2017	$	677
2018	1,286
2019	1,252
2020	958
2021	805
2022	691