GOODWILL AND OTHER INTANGIBLE ASSETS

The changes in goodwill by segment for the six months ended June 30, 2018 were as follows (in thousands):



	Environmental Services			Safety-Kleen			Totals
Balance at January 1, 2018	$	172,386		$	306,137		$	478,523
Increase from current period acquisition	21,626			—			21,626
Measurement period adjustments from prior period acquisitions	(78		)	—			(78		)
Foreign currency translation	(1,305		)	(1,515		)	(2,820		)
Balance at June 30, 2018	$	192,629		$	304,622		$	497,251

The Company assesses goodwill for impairment on an annual basis as of December 31, or at an interim date when events or changes in the business environment would more likely than not reduce the fair value of a reporting unit below its carrying value.

As discussed in Note 18, “Segment Reporting,” during the first quarter of fiscal year 2018 and as a result of operational and managerial changes in several of the Company’s businesses, the identification of operating segments in accordance with ASC 280, Segment Information, was changed. As a result of the Company's conclusions around the identification of operating segments, the Company also concluded that, for purposes of reviewing for potential goodwill impairment, it now has four reporting units, consisting of Environmental Sales and Service, Environmental Facilities, Kleen Performance Products and Safety-Kleen Environmental Services. The Company allocated goodwill to the newly identified reporting units using a relative fair value approach. In addition, the Company completed an assessment of any potential goodwill impairment for all reporting units immediately prior and subsequent to the reallocation and determined that no impairment existed.

As of June 30, 2018 and December 31, 2017, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):



	June 30, 2018						December 31, 2017
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	175,317	$	76,707	$	98,610	$	174,721	$	74,347	$	100,374
Customer and supplier relationships	399,012		170,866		228,146		399,224		158,972		240,252
Other intangible assets	37,431		31,107		6,324		36,766		31,592		5,174
Total amortizable permits and other intangible assets	611,760		278,680		333,080		610,711		264,911		345,800
Indefinite lived trademarks and trade names	122,840		—		122,840		123,328		—		123,328
Total permits and other intangible assets	$	734,600	$	278,680	$	455,920	$	734,039	$	264,911	$	469,128

Amortization expense of permits and other intangible assets was $8.6 million and $17.8 million in the three and six months ended June 30, 2018, respectively. Amortization expense of permits and other intangible assets was $9.7 million and $18.8 million in the three and six months ended June 30, 2017, respectively.

The expected amortization of the net carrying amount of finite-lived intangible assets at June 30, 2018 was as follows (in thousands):



Years Ending December 31,	Expected Amortization
2018 (six months)	$	16,927
2019	32,143
2020	29,850
2021	27,381
2022	27,222
Thereafter	199,557
	$	333,080