Goodwill and Other Intangible Assets - Summary of Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Intangible assets
Gross Carrying Amount	$ 74,393	$ 74,393
Accumulated Amortization	(38,491)	(34,301)
Net Amount	35,902us-gaap_FiniteLivedIntangibleAssetsNet	40,092us-gaap_FiniteLivedIntangibleAssetsNet
Amortization expense	4,190us-gaap_AmortizationOfIntangibleAssets	5,002us-gaap_AmortizationOfIntangibleAssets	2,118us-gaap_AmortizationOfIntangibleAssets
Customer-Related Intangible Assets [Member]
Intangible assets
Gross Carrying Amount	51,804	51,804
Accumulated Amortization	(24,415)	(21,490)
Net Amount	27,389	30,314
Patents [Member]
Intangible assets
Gross Carrying Amount	10,319	10,319
Accumulated Amortization	(10,319)	(10,319)
Other intangibles [Member]
Intangible assets
Gross Carrying Amount	12,270	12,270
Accumulated Amortization	(3,757)	(2,492)
Net Amount	$ 8,513	$ 9,778

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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-Section 45

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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