Commitments and Contingencies Extended Warranty (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Less: current portion of unearned revenue for extended warranty	$ 74,598		$ 74,598		$ 64,976
Extended Warranty [Member]
Beginning balance	30,271	$ 33,068	31,549	$ 33,654
Unearned revenue for new extended warranties	302	352	1,006	1,366
Unearned revenue recognized	(1,096)	(905)	(3,163)	(2,640)
Effect of change in exchange rates	121	(31)	206	104
Ending balance	29,598	32,484	29,598	32,484
Less: current portion of unearned revenue for extended warranty	4,305	4,134	4,305	4,134
Long-term unearned revenue for extended warranty within other long-term obligations	$ 25,293	$ 28,350	$ 25,293	$ 28,350

Total increase or decrease in the deferred revenue liability due to currency translation.

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Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

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The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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