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Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Contingency [Line Items]
Gross liability for unrecognized tax benefits, exclusive of interest and penalties	$ 15,167		$ 14,480
Unrecognized tax benefits that would affect effective tax rate	14,546		13,737
Interest and penalties on unrecognized benefits	1,379		$ 1,175
Estimated one-time transition tax	11,544
Payment of transition tax	1,000	$ 0
Estimated one-time transition tax, current	915
Estimated one-time transition tax, noncurrent	9,629
Settlement and Lapse of Statute
Income Tax Contingency [Line Items]
Unrecognized tax benefits within the next twelve months	$ 2,944

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The increase (decrease) during the period in the amount due for taxes based on the reporting entity's earnings or attributable to the entity's income earning process (business presence) within a given jurisdiction.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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