Goodwill and Intangible Assets (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2018

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

The carrying amount, including changes therein, of goodwill by reporting segment was as follows:

(in thousands)	Production & Automation Technologies			Drilling Technologies		Total
December 31, 2017	$	808,952		$	101,136	$	910,088
Purchase price adjustment *		(53	)		—		(53	)
Foreign currency translation		(3,269	)		—		(3,269	)
September 30, 2018	$	805,630		$	101,136	$	906,766

* Purchase price adjustment related to our 2017 acquisition of PCP Oil Tools S.A. and Ener Tools S.A.

The changes in the carrying value of goodwill by operating segment were as follows:

	Production & Automation Technologies		Drilling Technologies		Total
Balance at December 31, 2015	$	800,792	$	101,136	$	901,928
Foreign currency translation		651		—		651
Balance at December 31, 2016		801,443		101,136		902,579
Acquisitions		5,053		—		5,053
Foreign currency translation		2,456		—		2,456
Balance at December 31, 2017	$	808,952	$	101,136	$	910,088

Schedule of Intangible Assets

The components of our definite- and indefinite-lived intangible assets were as follows:

	September 30, 2018						December 31, 2017
(in thousands)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Definite-lived intangible assets:
Customer intangibles	$	569,832	$	309,355	$	260,477	$	572,415	$	276,655	$	295,760
Trademarks		36,307		20,648		15,659		36,312		17,821		18,491
Patents		38,514		22,959		15,555		38,679		20,449		18,230
Unpatented technologies		9,700		9,700		—		9,700		9,700		—
Drawings and manuals		3,047		2,163		884		3,067		2,109		958
Other		5,346		4,124		1,222		5,382		3,911		1,471
		662,746		368,949		293,797		665,555		330,645		334,910
Indefinite-lived intangible assets:
Trademarks		3,600		—		3,600		3,600		—		3,600
Total	$	666,346	$	368,949	$	297,397	$	669,155	$	330,645	$	338,510

The following table provides the gross carrying value and accumulated amortization for each major class of intangible assets:

	December 31, 2017						December 31, 2016
	Gross Carrying Amount		Accumulated Amortization		Net		Gross Carrying Amount		Accumulated Amortization		Net
Amortized intangible assets:
Customer Intangibles	$	572,415	$	276,655	$	295,760	$	566,602	$	229,902	$	336,700
Trademarks		36,312		17,821		18,491		36,296		14,013		22,283
Patents		38,679		20,449		18,230		38,106		16,662		21,444
Unpatented Technologies		9,700		9,700		—		9,700		9,700		—
Drawings & Manuals		3,067		2,109		958		3,001		1,942		1,059
Other		5,382		3,911		1,471		5,270		3,539		1,731
Total amortized intangibles		665,555		330,645		334,910		658,975		275,758		383,217
Unamortized intangible assets:
Trademarks		3,600		—		3,600		3,600		—		3,600
Total intangible assets	$	669,155	$	330,645	$	338,510	$	662,575	$	275,758	$	386,817

Estimated Future Amortization Expense related to Intangible Assets

Estimated future amortization expense related to intangible assets held at December 31, 2017 is as follows:

	Estimated Amortization
2018	$	52,357
2019		51,509
2020		50,059
2021		49,231
2022		47,683