Intangible Assets, Net (Notes)

6 Months Ended

Jun. 30, 2016

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, 2016							December 31, 2015							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	$	(3,969	)	$	3,203	$	7,551	$	(3,921	)	$	3,630	6.0
Pipeline rights-of-way	6,527		(2,619		)	3,908		6,414		(2,287		)	4,127		5.2
Intangible assets, net	$	13,699	$	(6,588	)	$	7,111	$	13,965	$	(6,208	)	$	7,757

Intangible asset amortization expense was $0.3 million and $0.6 million for the three and six months ended June 30, 2016, respectively, based upon estimates of useful lives ranging from 1 to 35 years. Intangible asset amortization expense was $0.3 million and $0.6 million for the three and six months ended June 30, 2015, respectively, based upon estimates of useful lives ranging from 1 to 20 years.

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

Remainder of 2016	$	588
2017	1,087
2018	1,087
2019	1,087
2020	792
2021	639