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Income Taxes (Narratives)(Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Operating Loss Carryforwards [Line Items] |  |  |
TaxBenefitFromRemeasurementofDeferredTaxesDuetoTaxReform | $ 33,400 |  |
transition tax on the deemed dividend on foreign earnings | 1,600 |  |
other tax impacts related to tax reform | $ 400 |  |
U.S. federal statutory tax rate | 35.00% | 35.00% | 35.00%
Operating Loss Carryforwards, Valuation Allowance | $ 1,200 | $ 1,200 |
Accumulated net earning | 428,419 | 315,573 |
Gross deferred tax assets | 18,600 | 34,400 |
Gross deferred tax liabilities | 86,800 | 107,500 |
Unrecognized Tax Benefits that Would Impact Effective Tax Rate | 430 | $ 1,293 | $ 814
Internal Revenue Service (IRS) [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Operating loss carryforwards | 0 |  |
State and Local Jurisdiction [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Operating loss carryforwards | 0 |  |
Foreign Tax Authority [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Operating loss carryforwards | 5,700 |  |
Accumulated net earning | $ 7,900 |  |

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- Definition Amount of deferred tax liability attributable to taxable temporary differences. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(15)(b)(2)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(2)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(26)(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(26)(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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