Income Taxes - Unrecognized Tax Liability (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 3,468	$ 9,553
Additions to:
Positions taken during the current year	40	54
Positions taken during a prior year	49	280
Exchange rate impact	19	57
Deductions due to:
Exchange rate impact	0	(11)
Positions taken during a prior year	(176)	(42)
Settlements with taxing authorities	0	(6,245)
Lapse of statute of limitations	(535)	(178)
Balance at end of year	$ 2,865	$ 3,468

Unrecognized Tax Benefits, Decreases [Abstract]

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Unrecognized Tax Benefits, Increases [Abstract]

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No definition available.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from foreign currency translation.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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