Intangible Assets - Amortized Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 60,724	$ 52,668
Accumulated Amortization	47,535	44,356
Net Carrying Value	13,189	8,312
Distribution networks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	38,060	38,060
Accumulated Amortization	38,060	37,422
Net Carrying Value	0	638
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	8,607	6,605
Accumulated Amortization	5,202	4,836
Net Carrying Value	3,405	1,769
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	370
Accumulated Amortization	92
Net Carrying Value	278
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	13,687	8,003
Accumulated Amortization	4,181	2,098
Net Carrying Value	$ 9,506	$ 5,905

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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